Heart rate variability in patients with diabetes mellitus, ischemic heart disease, and congestive heart failure. The prognosis of patients with heart disease and prediction of sudden cardiac death can be assessed through heart rate variability, an indirect measure of abnormal autonomic control. The authors have evaluated the heart rate variability by 24-hour ambulatory electrocardiographic monitoring in 25 diabetic patients, 19 ischemic heart disease patients, 18 congestive heart failure patients, and 10 normal subjects. Thirteen diabetic patients had autonomic neuropathy and 12 patients did not. Heart rate variability index (mean SD) in patients with diabetes mellitus, ischemic heart disease, and congestive heart failure was significantly lower (34.5 +/- 12.6 ms, 43.7 +/- 15.4 ms, and 34.6 +/- 15.8 ms vs 65.6 +/- 16.7 ms, p less than 0.05) than that of normal subjects. Mean SD was significantly lower in patients with autonomic neuropathy as compared to patients without autonomic neuropathy (26.4 +/- 6.5 ms vs 44.2 +/- 11.0 ms, p less than 0.05) mean SD as compared to survivors: 49 +/- 7 ms in patients with mild ischemic heart disease, 48 +/- 15 ms in patients with severe ischemic heart disease, and 23 +/- 7 ms in patients who died. Similarly, the mean SD in 4 congestive heart failure patients who died was lower significantly (p less than 0.05) than in those who survived (19.0 +/- 5.6 ms vs 40.0 +/- 14.5 ms). Among congestive heart failure patients, clinical improvement by therapy was associated with a significant increase in mean SD. When the mean SD of 30 ms was used as the cutoff point for detection of autonomic dysfunction or patient death, specificity exceeded 90% and sensitivity was 75%.(ABSTRACT TRUNCATED AT 250 WORDS)


Comparison of logistic regression and Bayesian-based algorithms to estimate posttest probability in patients with suspected coronary artery disease undergoing exercise ECG. Two multivariate methods, a logistic regression-derived algorithm and a Bayesian independence-assuming method (CADENZA), were compared concerning their abilities to estimate posttest probability of coronary disease in patients with suspected coronary disease. All patients underwent exercise testing within 3 months prior to coronary angiography. Coronary disease was defined as the presence of one or more vessels with greater than or equal to 50% luminal diameter narrowing. A group of 300 patients (disease prevalence = 37%) was used to derive the algorithm. Another group of 950 patients was used to validate the algorithm and compare it to CADENZA. Seven variables (age, sex, symptoms, diabetes, mm ST depression, ST slope, and peak heart rate) were used to generate posttest probabilities for each method. The receiver operating characteristic curve area for the logistic regression method (0.81 +/- 0.01) was significantly higher than CADENZA (0.75 +/- 0.01; p less than 0.05). There was, however, no difference in the calibration of the two methods. When given equivalent variable information, the logistic regression algorithm had better discrimination than CADENZA for estimating the probability of coronary disease following exercise electrocardiography.


Factors associated with recidivism in a criminal population. The present study is a follow-up of a sample of 348 men convicted of manslaughter, attempted manslaughter, or arson who were released from incarceration. Multiple factors assessed at the time of incarceration, including demographic, behavioral, family history, and biochemical variables, and psychiatric diagnoses were used in an attempt to discriminate between those who became recidivists during the follow-up period and those who did not. Violent recidivism was most strongly associated (sensitivity of 90%) with impulsivity of the original crime in killers and attempted killers; for arsonists, having made a suicide attempt was the strongest predictor (68% sensitivity). For predictive purposes, both single factor associations and multiple entries into discriminant analysis produced too many false-positives, i.e., the high rate of false designation as recidivist remained a problem.


An analysis of treatment services provided in group homes for adults labeled mentally ill. Although group homes for adults labeled mentally ill have been the focus of significant attention in deinstitutionalization discussions, substantive research on their operation has been lacking. The present study addresses past limitations by focusing on a well-defined sample of small group homes, with higher staffing levels and in-home treatment provided. Thirty homes were randomly selected; all home residents (N = 253) were studied. Data were collected from case managers, residents, and home staff to assess residents' functioning, services and treatments provided, and the environment of the home. The findings were examined in terms of adequacy and appropriateness of care provided in the home, using accepted guidelines. The results indicated that there are aspects of a homelike environment, emotional support from staff, and skill-development activities within the home. However, an institutional focus still seems prevalent, along with limited rehabilitation and socialization activities. Residents expressed high levels of satisfaction, which may reflect their dislike of the group home alternative, e.g., the state hospital. Policy implications are discussed vis-a-vis current efforts to move away from group homes toward supported housing initiatives.


The National Institute of Mental Health Panic Questionnaire. An instrument for assessing clinical characteristics of panic disorder. This paper introduces a new self-report inventory, the NIMH Panic Questionnaire (NIMH PQ), for obtaining and quantifying comprehensive information about the clinical characteristics of panic disorder in patients with previously diagnosed or suspected illness. Fifty-two patients who met DSM-III-R criteria for panic disorder completed the NIMH PQ; their responses were compared with data derived from 16 similar or identical questions on the Schedule for Affective Disorders and Schizophrenia modified for anxiety disorders. There were no significant differences between the two instruments on 15 of the 16 (93.7%) items tested. The one exception revealed a greater proportion of patients versus physicians endorsing "spontaneous" panic, and a nonsignificant trend for physicians over patients endorsing anticipatory anxiety with greater frequency. The NIMH PQ offers a potentially useful clinical and research tool in the assessment of patients with known or suspected panic disorder.


Depression in Korean immigrants in Canada. I. Method of the study and prevalence of depression. This study reports the prevalence and risk factors of depression in a large representative community sample of adult Korean immigrants in Toronto, Canada. The Center for Epidemiologic Studies-Depression scale was used to measure depression by applying DSM-III criteria. Results in general suggest few differences between the immigrant community and the larger communities in Canada and the United States. Depressive syndrome was present in 4.5% of the sample, a prevalence similar to rates reported by the Epidemiologic Catchment Area studies. The risk factors associated with depression in larger populations were also found to be related to depression in this sample. Gender, marital status, intention to re-migrate, and social support were the most powerful correlates of depressive syndrome. In summary, Korean immigrants in Toronto are not exceptionally vulnerable to depression, and the social support from informal ethnic networks at the time of arrival has long-lasting effects on their mental health. Future research should focus on how the informal social supports available at the time of arrival are maintained by immigrants and the precise ways in which they exert long-term protective effects.


Depression in Korean immigrants in Canada. II. Correlates of gender, work, and marriage. The Center for Epidemiologic Studies-Depression scale was used to measure depression by applying DSM-III criteria to a community sample of 860 adult Korean immigrants residing in Toronto, Canada. A total of 2.6% of men (95% confidence interval, 1.1% to 4.1%) and 6.7% of women (95% confidence interval, 4.3% to 9.1%) manifested depressive syndrome, rates not substantially different from those reported in North American community populations. The study also identified the subgroups in which the gender differences in depression were the greatest. Both the role demand (or double burden) and power explanations of gender differences might be supported. The mental health implications of social roles, including gender role, may be better understood from cross-cultural or multicultural perspectives.


Is risk for substance abuse unitary?

Is risk for substance abuse unitary? The hypothesis that risk for substance abuse is not unitary was tested by a log linear regression analysis. A series of risk factors was evaluated in a sample of 219 nonhospitalized, nontreated, young male and female subjects. Risk for alcohol abuse/dependence was independent of risk for drug abuse/dependence and the risks were additive in the prediction of lifetime substance abuse. Antisocial personality diagnosis predicted alcohol abuse/dependence, family history of drug abuse predicted drug abuse/dependence, and, additively, they predicted alcohol and drug abuse/dependence diagnosis over a lifetime. These data support a hypothesis that risk for substance abuse is not unitary.


Prevalence estimates of substance abuse in schizophrenia and their correlates. Published estimates of the prevalence of substance abuse in schizophrenia were correlated with several aspects of the studies in which they were obtained. Higher estimates of alcohol and stimulant abuse were found in studies published more recently. Rates of alcohol abuse were particularly high in one rural investigation. Rates of stimulant abuse were highest when patients were asked directly about use of stimulants. Increased prevalence estimates in more recent years could not be attributed to method of assessing substance abuse, method of defining substance abuse, or characteristics of the study sample.


Ligational behavior of N-substituted acid hydrazides towards transition metals and potentiation of their microbiocidal activity. New complexes of Cu(II), Ni(II), and Co(II) with 3-benzoyl-1-[2-N-(substituted-2'-thienyl methylmethylene/methylene)] prop-2-ene-1-oic acid hydrazides have been synthesized and characterized by elemental analysis, molecular weight determination, molar conductance, and magnetic moment and spectroscopic techniques. Conductance measurements indicate the nonionic nature of the complexes. From the spectroscopic studies, it has been concluded that the N-substituted acid hydrazides act as tridentate ligands forming an O-N-S conjugate system and coordinating with metal ions through oxygen of carbonyl group, nitrogen of azomethine, and sulphur of thiophene moiety. Octahedral geometry has been proposed for all the complexes. The ligands and their complexes were tested for in vitro growth inhibitory activity against phytopathogenic fungi viz. Alternaria alternata, Colletotrichum capsicum, Fusarium oxysporum, and Rhizoctonia solani at 28 degrees C; and bacteria viz. gram positive Bacillus subtilis and gram negative Escherichia coli at 37 degrees C by a two-fold serial dilution technique. In some cases an increase in the biocidal activity of the ligands as a consequence of coordination with metal ions was observed in terms of minimum inhibitory concentration (MIC) values. The trend of growth inhibition in the complexes was found to be in the order: Cu greater than Ni greater than Co.


The binding of polyamines and magnesium to DNA. 1. The binding of spermine and Mg2+ to DNA has been investigated using the dye arsenazo III to measure unbound cations. 2. The apparent dissociation constant, Kd, of DNA for spermine has been found to be 7.4 +/- 3.9 x 10(-8) M and that for Mg2+, 6.5 +/- 3.3 x 10(-7) M. 3. Binding of spermine in the presence of 1 mM Mg2+ has been shown to have a Kd of about 4 x 10(-6) M. 4. Magnesium ion (2 mM) halves the concentration of spermine needed to cause DNA aggregation. 5. Spermidine binds to DNA with a similar affinity to spermine but 3,3'-iminobispropylamine and 1,5,9,13-tetra-azatridecane bind with a lower affinity. The naturally occurring polyamines thus have a higher affinity for DNA than the related polyamines which do not occur naturally. 6. Binding of spermine or spermidine to DNA alters the spectrophotometric absorbance of DNA at 260 nm.


Arsenic-75 nuclear magnetic resonance: study of the interaction of arsenate with various molecules of biological interest. 75As NMR (Nuclear Magnetic Resonance) was used as a probe of arsenate interactions in solution. The linewidth at half-height of the 75As NMR signal of arsenate was studied as a function of solution pH and temperature. Below pH 11.5, the 75As signal was too broad to be detected, but at higher pH, up to pH = 13.5, the signal became much narrower. This indicates that the arsenate species AsO4(3-) is quite symmetric, but the asymmetry of HAsO4(2-) is sufficient to cause extensive quadrupolar relaxation of the 75As nucleus. A full pH range 75As and proton NMR study of the interaction of arsenate with ethanol, ethylene glycol, glycerol, ribose, mannose, glucose, gluconic acid and acetate was undertaken in order to follow arsenate ester formation. The 75As line broadening effects and the proton ligand shifts observed indicate that complexation of arsenate by ribose, mannose, glucose, ethanol, ethylene glycol, and glycerol occurs at pH 12.7. However, no significant interaction is detected by NMR with gluconic acid or acetate. The effect of the nucleoside adenosine is quite small and those of phosphate and of the nucleotides AMP and ADP are negligible. The interaction of arsenate with potential cationic centers, such as the basic amino acids lysine and arginine and some macrocyclic triamines, was also studied. Such interaction depends on the pKa for protonation of the amine groups.


A new class of alkaloids from a dendrobatid poison frog: a structure for alkaloid 251F. Alkaloids of a new class are present in skin extracts of the dendrobatid poison frog, Minyobates bombetes, of Colombia. The structure of the major alkaloid of this class, 251F, has been determined as a trimethylcyclopenta[b]quinolizidinemethanol 1 by nmr, gc-Ft-ir, and ms studies including ms-ms. At least nine congeners of 251F were detected in these extracts.


Isolation and structure determination of new macrolide antibiotics. Three new bafilomycin-like compounds PD 118,576-A1 [1], PD 118,576-A2 [2], and PD 118,576-A3 [3] were isolated from a new soil Streptomyces species (WP 3913). The structures of PD 118,576-A1, PD 118,576-A2, and PD 118,576-A3 were elucidated on the basis of spectroscopic studies including 2D nmr.


Antibacterial activity of crinitol and its potentiation. An acyclic diterpene alcohol, crinitol [1], was identified in a marine brown alga, Sargassum tortile, as the principal antibacterial agent against Gram-positive bacteria, among which Propionibacterium acnes was most sensitive and, Staphylococcus aureus was least. To enhance its activity, crinitol was combined with several antioxidants, which presumably retard oxidative destruction of this molecule which possesses two easily oxidizable allylic alcohol groups. Two synthetic antioxidants, BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene), significantly enhanced the activity of crinitol, especially against Streptococcus mutans. Interestingly, crinitol also synergized BHT and BHA against this cariogenic bacterium.


Effect of ursolic acid from epicuticular waxes of Jacaranda decurrens on Schizaphis graminum. Ursolic acid from Jacaranda decurrens showed toxicity and feeding deterrency towards the greenbug Schizaphis graminum. Biological activity was determined by analyzing ursolic acid effects on the survival, reproductive index, and population growth rate of the greenbug. Survival and reproductive index decreased in direct proportion to ursolic acid content in the diet. The population growth rate decreased markedly when the aphids were fed on barley leaves sprayed with ursolic acid dissolved in DMSO, in comparison to leaves sprayed only with DMSO. The feeding behavior of the greenbug was also affected by ursolic acid. Ingestion time on diet with 0.1 mM was reduced about 30% in relation to the ingestion time on control diet.


Psammaplysin C: a new cytotoxic dibromotyrosine-derived metabolite from the marine sponge Druinella (= Psammaplysilla) purpurea. The new, cytotoxic dibromotyrosine-derived metabolite psammaplysin C [3], in addition to the two known psammaplysins A [1] and B [2], was isolated from the marine sponge Druinella purpurea. All three compounds were found to possess moderate in vitro cytotoxicity towards the human colon tumor cell-line HCT116.


Evaluation of oxygen desaturation events in singleton pregnancies. Previous investigators have demonstrated that oxygen desaturation may occur in laboring women. The purposes of this study were to identify groups at risk for desaturation and to seek correlation with newborn outcome. Volunteers in labor were evaluated for oxygen desaturation, analgesic exposure, magnesium sulfate administration, and various medical illnesses. Desaturations were noted more frequently in women exposed to narcotic analgesics, sedatives, and magnesium sulfate. A trend toward more desaturations in the women with preeclampsia was noted. Although desaturations related to narcotic analgesics and sedatives are most likely due to hypoventilation, the mechanism in women treated with magnesium sulfate is uncertain. Maternal peripartum desaturations did not result in unfavorable neonatal Apgar scores, cord blood gas measurements, or neonatal oxygen desaturation values, but the staff was aware of the events and prompt treatment was instituted.


Cholelithiasis in infants receiving furosemide: a prospective study of the incidence and one-year follow-up. Cholelithiasis has been reported to occur rarely in infants. To determine the incidence of cholelithiasis in infants receiving furosemide, we prospectively performed ultrasonograms on 86 patients. We studied 42 patients receiving furosemide (subjects) and 44 patients not receiving furosemide (controls). There was a significantly higher incidence of gallstones in subjects (21%) than in controls (2%) (P less than .05). When followed over 1 year, the gallstones did not resolve. There were no significant differences in the dosage of furosemide, gestational age, placement of umbilical venous catheters, or amount of total parenteral nutrition (TPN) between subjects with and without gallstones. However, subjects received more days of TPN (16.7 +/- 15.1) than controls (8.4 +/- 13.2) (P less than .05). These data show that the incidence of cholelithiasis is higher than previously suspected in infants receiving furosemide. Thus, furosemide, either independently or in conjunction with the use of TPN, predisposes infants to the development of cholelithiasis.


Misdiagnosis of congenital chloride-losing diarrhea. Congenital chloride-losing diarrhea is a recessively inherited disorder due to the absence of chloride-bicarbonate exchange in the small bowel. Malabsorption of chloride leads to osmotic diarrhea, electrolyte abnormalities, and dehydration. If left untreated, the infants fail to thrive and have a very high mortality. Clinically, affected patients develop secretory diarrhea in utero resulting in distended bowel loops and polyhydramnios. At birth these infants have profuse watery diarrhea that may be confused with urine. Thus, the correct diagnosis is often missed, and they may be subjected to unnecessary interventions. If diagnosed early, the electrolyte abnormalities are easily corrected and the prognosis is good. We report two patients who were initially evaluated for other conditions but later proved to have congenital chloride-losing diarrhea. The cases emphasize the importance of having a high index of suspicion in patients with a history of polyhydramnios, prematurity, and watery stools.


Validity of postnatal assessments of gestational age in low birthweight infants from a Caribbean community. The Dubowitz assessment of gestational maturity was compared with the best obstetric estimate of gestational age based on date of last menstrual period (LMP) or ultrasonography performed early in the pregnancy or both. This study involved 384 low birthweight infants admitted to the neonatal tertiary center in Guadeloupe, French West Indies, during the period 1986 through 1988. The Dubowitz assessment exceeded the best obstetric estimation by an average of nearly 5 days. This overestimation by the Dubowitz method was observed at every gestational age and was greatest at gestational ages of less than 35 weeks. The physical characteristics of the postnatal assessment were in closer agreement with the best obstetric estimate than the neurological characteristics. These findings concur with other investigations that indicate that the Dubowitz postnatal assessment of gestational age overestimates the gestational age interval from date of LMP in low birthweight and preterm infants.


Effects of saline instillation during tracheal suction on lung mechanics in newborn infants. To evaluate the effect of saline instillation prior to tracheal suction on lung mechanics in mechanically ventilated newborn infants, we studied pulmonary mechanics in nine infants with respiratory distress syndrome (RDS) and nine infants with meconium-aspiration syndrome (MAS) at a mean postnatal age of 3 days. Pulmonary mechanics were measured at 10 minutes prior to, and at 10, 20, and 30 minutes after tracheal suction with saline instillation. Suction and study protocol were repeated within 12 hours without saline instillation. The sequence of the study with and without saline instillation was randomly assigned. In infants with RDS, tracheal suction had no effect on pulmonary compliance or airway resistance with and without saline instillation. In infants with MAS, there was no change in compliance after tracheal suction with and without saline instillation. Airway resistance decreased by 35% after tracheal suction with saline instillation in infants with MAS; tracheal suction without saline instillation had no effect on airway resistance. We conclude that saline instillation into trachea as commonly done during tracheal suction has no deleterious effects on lung mechanics in newborn infants.


Apnea in subsequent asymptomatic siblings of infants who had an apparent life-threatening event. Infants experiencing apparent life-threatening events (ALTE) have been reported to have elevated frequencies of periodic breathing and obstructive apnea when compared to presumably normal control groups. Whether these characteristics extend to the siblings of ALTE infants remains unknown. This study compared, retrospectively, the apnea indices of 13 first-born infants experiencing an ALTE with their subsequent asymptomatic siblings who had undergone polygraphic sleep apnea evaluations (including electrocardiogram, chest wall movements, expired CO2, and transcutaneous pulse oximetry). Gestation, birthweight, age at study, apnea and periodic breathing indices, and oxygen desaturations were compared. Regression analyses revealed that adjustments for gestational and postnatal age eliminated differences in apnea indices. ALTE infants and their subsequent siblings experienced similar rates of apnea. Neither group had elevated rates of prolonged central apneas (greater than 10 seconds duration) or periodic breathing (greater than 5% sleep time). Neither group had subsequent severe apneas. The use of polygraphic study and cardiac/apnea monitors in subsequent siblings of ALTE are unnecessary and should be considered only when there is parental disagreement.


Improving the prediction of surfactant deficiency in very low-birthweight infants with respiratory distress. With the availability of exogenous surfactant therapy, distinguishing between surfactant deficiency and other causes of respiratory distress soon after birth is critical. Of 149 very low-birthweight (VLBW) infants of 24 to 30 weeks' gestation, 107 (72%) had both clinical and radiographic features of respiratory distress syndrome (RDS). Analysis of amniotic fluid obtained within 24 hours before birth or of the initial tracheal aspirate after birth for phosphatidylglycerol (PG) showed that absence of PG had a positive predictive value (PPV) of 80% for predicting RDS, while an immature lecithin/sphingomyelin (L/S) ratio had a PPV of 86% with a 68% specificity. When PG was absent and the L/S ratio was immature, the PPV for RDS increased to 89% (97% specificity). Phospholipid analysis was superior to gestational age alone in predicting RDS (P less than or equal to .02). Receiver operating characteristic (ROC) analysis detected different thresholds for immature L/S ratios for amniotic fluid (2.0) and initial tracheal aspirate (3.0) for predicting RDS. A tracheal aspirate L/S ratio less than or equal to 3.0 predicted RDS with 91% accuracy, while an amniotic fluid L/S ratio less than or equal to 2.0 predicted RDS with 90% accuracy. ROC curve thresholds for either tracheal aspirate or amniotic fluid permit selection of VLBW infants most likely to benefit from surfactant treatment. These analyses improve the accuracy of diagnosing surfactant-deficiency-associated RDS using only clinical and radiographic diagnoses, and may permit a more focused approach for rescue surfactant therapy in infants presenting with clinical symptoms of respiratory distress.(ABSTRACT TRUNCATED AT 250 WORDS)


Patterns of illicit drug use at the time of labor in a private and public hospital. The majority of prevalence data on perinatal substance abuse describe low socioeconomic patient populations. This study of illicit drug use at the time of labor was done to identify patterns of drug use in both private and nonprivate patients. Anonymous urine samples were collected from 1000 patients, 500 admitted in labor to a private hospital and 500 admitted to a public hospital. All samples were screened for cocaine, opiates, cannabinoids, and amphetamines. A positive result of screening for any drug was detected in 8.2% of patients. More positive results of screening for any drug were found in nonprivate patients (11.4%) than private patients (5%), with nonprivate patients significantly more likely to test positive for cocaine or cannabinoids or both. Black patients contributed 64.5% of the positive tests for cocaine, significantly more than white (17.6%) or Hispanic patients (17.6%), whereas white patients contributed significantly more positive tests for cannabinoids (85%) than black (5.4%) or Hispanic patients (7.1%). Assessment of patterns of perinatal drug use in communities will support appropriate allocation of resources and targeting of patient and provider education.


Reducing the hypoxemia, bradycardia, and apnea associated with suctioning in low birthweight infants. Hypoxemia and bradycardia are major complications associated with suctioning the neonate. Apnea has been reported following caregiving during peak hours of activity in a neonatal intensive care unit (NICU). This study determined the incidence of hypoxemia, bradycardia, and apnea associated with the standard suction protocol used in one NICU. None of the 17 low birthweight infants suctioned between the peak caregiving activity hours of 8 and 11 AM exhibited bradycardia or apnea. Eleven of the 17 infants experienced no hypoxemia. Six infants displayed hypoxemia that lasted for less than 3 minutes. None of the infants exhibited bradycardia or apnea in association with this suction protocol. Patterns of escalating blood pressure noted in this study are worrisome because of the increased risk of intraventricular hemorrhage.


Reducing neonatal transfusions.

Reducing neonatal transfusions. In an attempt to prevent blood transfusions from being ordered unnecessarily in our neonatal intensive care unit (NICU), we developed transfusion guidelines and prospectively evaluated their impact on our transfusion practices. Initially, 17% of our packed red blood cell transfusions (PRBCT) did not meet our guidelines. However, 6 months following development of the guidelines, this decreased to 9%, and 12 months later, it decreased to 1%. Although the guidelines are clearly arbitrary, they do provide for consistency within our NICU and a method of evaluating our own use of PRBCT.


The grief response to mid-trimester fetal loss. This descriptive study examines the grief response of mothers who experienced a fetal loss in the middle trimester of pregnancy. Twenty mothers who lost a baby through spontaneous abortion or perinatal death within 1 year participated in this study. Data were collected by mailed questionnaires. All characteristics typical of the grief response were identified, including despair, anger or hostility, guilt, loss of control, rumination, depersonalization, somatization, and death anxiety. Comparison of the study population to a group of parents who suffered the loss of a child and to a group of women who had suffered the death of a close relative demonstrated that the study group presented a grief response similar in nature and intensity to the two normative groups. This study supports previous studies that indicated the existence of grief after mid-trimester fetal loss. Replication of this study with a larger sample is recommended to further support these findings.


The California Diabetes and Pregnancy Program: implementation of a multicenter experience with diabetic pregnancies. The California Diabetes and Pregnancy Program (CDAPP) began in 1984 as a multicenter, collaborative project with support provided by the state Department of Health Services, Maternal and Child Health Branch. Between its inception and 1988, it expanded from three to eight perinatal regions, making the CDAPP model of care available to patients in 19 clinical affiliate sites. The care was provided by a multidisciplinary team composed of physicians, a diabetes educator, a registered dietician, a social worker, and appropriate consultants. The elements of this model of care included comprehensive patient education, active patient participation in care, maternal and perinatal medical assessment, and collection of standardized patient information adequate to allow a programmatic and medical evaluation of the CDAPP. Despite impressive growth of the program by December 1988, statewide implementation of CDAPP is incomplete.


Variability in the LAL test: comparison of three kinetic methods for the testing of pharmaceutical products. Data presented in this study indicate that there is considerable variability in spike recoveries between three different kinetic LAL methods as used for the testing of a variety of parenteral products. However, successful spike recoveries were observed for each of the thirteen products under test on at least one of the three kinetic methods used, suggesting that problems caused by spike recovery variability may be easily controlled in the laboratory by flexibility in the choice of method.


Comparison of different rubber stoppers; the effect of sterilization on the number of particles released. The effect of sterilization on the number of particles released from five different types of rubber stoppers, as well as on their surface roughness and elemental composition before and after sterilization is described. The stoppers were immersed in 200 ml of 0.9% sodium chloride solution in conical flasks. The number of particles released into the sodium chloride solution was measured by Coulter Counter. The surface roughness and the elemental composition of the stoppers were determined by SEM/EDX. All measurements were made both before and after sterilization at 121 degrees C to F0 15 mins. The number of particles released from a stopper during sterilization varies considerably between different stoppers and even between different batches of the same stopper. The only non-siliconized stopper in this study performed well. The absence of surface siliconization may have contributed to this performance. The scanning electron micrographs revealed well the differences in the surface roughness of the stoppers. The sterilization generally increases the surface roughness of the samples. The x-ray microanalysis revealed that the elemental composition of the stoppers may vary not only between different types of stoppers but also between different batches of the same stopper.


Differences in trauma care among pediatric and nonpediatric trauma centers. To characterize pediatric trauma care, state trauma registry data from all designated trauma centers in Pennsylvania were divided into three categories, that from: (1) pediatric centers, (2) urban nonpediatric centers, (3) and rural nonpediatric centers. From October 1, 1986 through September 30, 1989 (3 years), 4,615 patients less than 15 years old were admitted to 28 trauma centers in Pennsylvania. Nonpediatric centers cared for the majority of children (2,734, 59.2%), but the average number of children treated per nonpediatric institution (105.1 per year) was far fewer than the average treated in the pediatric centers (940.5). Pediatric trauma centers in the state treated a younger population (6.4 +/- 4.2 years, mean +/- SD) compared with urban and rural nonpediatric centers (8.4 +/- 4.2 and 8.1 +/- 4.3 years, respectively; P less than .05). Pediatric centers received proportionately more children by transfer (56.2%), victims of falls (34.6%), pedestrian injuries (16.8%), and head and neck injuries (41.8%, all P less than .05). Nonpediatric centers received children directly from the scene of injury more frequently than transferred from other hospitals. The male:female sex ratio in urban nonpediatric centers was significantly higher (70.1%, P less than .05) than in the other two groups. Rural nonpediatric centers cared for a higher proportion of motor vehicle passengers (28.5%) and patients classified as "other" in the state registry, a category to which bicycle injuries are assigned (28.2%, P less than .05). Mortality was highest in rural nonpediatric centers (6.2%). The death rate in pediatric centers and urban nonpediatric centers were similar (4.1%) and significantly lower (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)


Tracheostomy in children with emphasis on home care. Tracheostomy in children is not a benign procedure. Tracheostomy-related mortality rates among children have been previously reported to be as high as 10% to 27%. Children with tracheostomies are especially vulnerable after home discharge with mortality rates of 0.5 to 2 deaths per 100 months at home. In order to assess the impact of extensive parental education and home nursing care on tracheostomy-related mortality, we report our experience over 9 years with 44 children receiving tracheostomies. Each child was maintained at home with a tracheostomy for an average of 19 months for a total of 635 months of home tracheostomy care. Indications for tracheostomy were tracheomalacia (32%), obstructive airway lesions (23%), central nervous system lesions (16%), vocal cord paralysis (9%), Pierre Robin syndrome (9%), and a list of miscellaneous conditions (11%). Our tracheostomy care regimen begins with intensive parental training in tracheostomy management for a minimum of 10 days prior to discharge. Home nursing was arranged for 77% of these children for an average of 11 hours per day at the time of discharge. Eighty-three percent had home apnea monitors. Discharge of these children was delayed or transfer to a secondary hospital was made when parents failed to show adequate proficiency in tracheostomy management with existing home nursing. Eight percent were ventilator dependent at discharge. As of January 1, 1989, 34% of these children have been decannulated. There were six deaths, all due to underlying disease. There were no tracheostomy-related deaths in hospital or after discharge home.(ABSTRACT TRUNCATED AT 250 WORDS)


Treatment of infantile subglottic hemangioma with electrocautery. Laryngeal subglottic hemangioma is a rare but potentially life-threatening congenital lesion that can compromise that infant airway. A multitude of medical and surgical modalities have been used in the treatment of this lesion but no single approach has received universal acceptance. Three infants with subglottic hemangiomas were treated successfully with electrocautery; each was managed without tracheostomy. Bronchoscopic electrocautery appears to be a safe, effective, inexpensive way to manage infantile subglottic hemangioma.


Industry perspective on the validation of column-based separation processes for the purification of proteins. Parenteral Drug Association. Validation of column-based separations is necessary to ensure the quality and safety of protein and peptide products produced by rDNA, peptide synthesis, and hybridoma technologies. Process validation for column-based separations includes qualification of raw materials, equipment, and the purification process. Combined with in-process control and quality control of the final product, column validation ensures that a uniform product is produced consistently from batch to batch. In the best case, validation is designed into the process. During process design, techniques are selected which can remove impurities and contaminants. Equipment and chromatographic media which can perform reproducibly are selected. Column performance standards, cleaning and regeneration routines, and column life should be considered as early as possible. Clearance studies should be planned and implemented to ensure that a product is produced with the requisite purity. There are no explicit rules for process validation of column-based separation processes. This document is intended to serve as a starting point for those needing to validate column-based separation processes.


Familial pheochromocytomas with unusual associations. Pheochromocytoma occurs in a familial pattern in approximately 10% of patients. Although most familial pheochromocytomas are an expression of the genetic abnormality of neuroectodermal dysplasia or the genetic syndrome of multiple endocrine neoplasia, some familial pheochromocytomas occur without associated disease. Two patients with familial pheochromocytoma are described. One had an extraadrenal tumor, producing severe renal artery stenosis and in whose family pheochromocytomas were found in three successive generations. A second had multiple pheochromocytomas associated with von Hippel-Lindau disease and a family member with multiple endocrine neoplasia type 2. The combinations and permutations of these genetic entities form discrete syndromes, with other peculiar interrelationships, pathologically related to an aberration in the migration, growth, and differentiation of the neural crest cells, and emphasizing their common neuroectodermal origin. The unique features that characterize the familial pheochromocytomas and cause diagnostic and therapeutic challenges are reviewed.


Serial measurement of urinary VMA and HVA levels from one infant: a study for neuroblastoma mass screening. Urinary vanillylmandelic acid (VMA), homovanillic acid (HVA), and creatinine in 188 samples from one infant during the ages of 1 to 12 months were measured serially by high-performance liquid chromatography (HPLC). The mean VMA and HVA levels of the total 188 samples in this study were 11.9 +/- 1.39 and 22.9 +/- 2.92 micrograms/mg creatinine with coefficients of variation (CVs) 11.7% and 12.8%, respectively; and of 76 samples from 5 to 12 months of age, 12.3 +/- 0.84 and 23.1 +/- 2.03 micrograms/mg creatinine with CVs 6.8% and 8.8%. The CVs of VMA and HVA levels expressed in microgram per milligram of creatinine had decreased after 6 months of age (VMA, 5.0% to 8.3%, HVA, 5.3% to 8.4%). Chromatograms demonstrated the similar pattern from 1 to 12 months of age, although the infant had been fed foods typical in Japan, which included breast milk, seasonal fruits, vegetables, fish, chicken, and meat. Diurnal fluctuations of VMA and HVA levels in urine were not significant. When HPLC is used for measurement of VMA, HVA, and creatinine, it is not necessary to restrict foods that cause false-positive results in the qualitative VMA test from the infant's diet. Furthermore, random urine samples obtained throughout the 12 months could be effectively used for the measurement of these substances.


Index of pulmonary expansion: a new method to estimate lung hypoplasia in congenital diaphragmatic hernia. In order to find a simple method for assessing the degree of lung hypoplasia in congenital diaphragmatic hernia (CDH), we measured an index of pulmonary expansion (V/P: expiratory tidal volume over inspiratory pressure) in 23 pulmonary normal and 16 CDH neonates. We also measured V/P in 9 newborn lambs, 6 with experimentally induced CDH and 3 controls, and compared V/P values with fractional lung masses (FLM: lung weight over body weight). In animals, the correlation between V/P and FLM was significant (P less than .05), whereas there was a very significant inverse correlation between pulmonary interstitial emphysema found at postmortem and FLM (P less than .01). These findings suggest that V/P could be an indicator of lung hypoplasia and, therefore, of sensitivity to barotrauma. In neonates with CDH, this index could be useful to make comparisons between series and to separate infants who cannot be ventilated at usual pressures without significant barotrauma.


CT differentiation of benign and malignant lung nodules in children. The superiority of computed tomography (CT) for detection of lung nodules has been documented and attempts have been made to distinguish benign from malignant lesions in adults. We attempted to characterize lung nodules in 12 children with solid malignant tumors (aged 8 months to 17 years) in an effort to differentiate benign from metastatic disease. All scans were performed at 10-mm contiguous intervals on a GE 9800 CT scanner. The scans were retrospectively viewed by two pediatric radiologists independently and without knowledge of the pathological findings. All biopsies were done via open thoracotomy. The CT findings were correlated with pathology results. Twelve children had 13 nodules biopsied. Six of these showed malignancy, two showed inflammatory changes, and two had a reactive subpleural lymph node. In three children, no abnormality was found and a biopsy was not obtained. One child had a metastatic nodule in one lung, and a simultaneous inflammatory nodule in the other. The radiologists agreed with each other on the CT interpretation in 11 of 13 surgically explored areas. They correctly predicted malignancy in four cases and correctly excluded it in two cases. However, they were simultaneously incorrect in five instances. Our conclusion is that, contrary to reports in adults, a tiny nodule may be either benign or malignant. Malignancy cannot be separated from benign disease by CT established criteria.


Reflux strictures of the esophagus in children. Although the therapeutic approach to gastroesophageal reflux in children is well established, there are differences of opinion regarding the management of esophageal strictures, viz bougienage with medical therapy, fundoplication without dilatation, preoperative dilatation followed by fundoplication with intraoperative and postoperative dilatation, or resection and interposition. Sixteen consecutive children (mean age, 30.2 months) with reflux strictures were evaluated, constituting 12% of children operated on for gastroesophageal reflux. The strictures became clinically apparent 22.4 months (mean) from the onset of symptoms and were diagnosed by contrast studies and endoscopy. At first endoscopy all the patients had well-established fibrotic strictures. The strictures were mostly situated in the middle or lower esophagus and 7 were longer than 3 cm in length. All 16 were treated with antacids, H2-receptor blockers (Cimetidine), prokinetic agents, and intense nutritional resuscitation, together with preoperative stricture dilatations (average, 3.6 times). This was followed by fundoplication when nutritional parameters had been restored, esophagitis improved, and the strictures dilated to adequate size. Seven children required concomitant gastrostomies for prograde esophageal dilatations. Twelve children needed postoperative esophageal dilatations. The results were satisfactory in 14 (88%). Two required endoesophageal resection for localized unyielding strictures. One child responded only after failed reflux surgery was corrected at a second procedure. During an average follow-up of 8.2 years (range, 3 to 11) there has been no stricture recurrence and growth velocity was restored in all. We conclude that our preferred method is preoperative in-hospital management of gastroesophageal reflux with maximum nutritional support and careful evaluation of the degree and extent of esophagitis and fibrous scarring.(ABSTRACT TRUNCATED AT 250 WORDS)


Isolated blunt liver trauma: is nonoperative treatment justified? During the past 8 years 13 children with isolated blunt liver trauma were managed nonoperatively. All patients selected for this management were hemodynamically stable after initial resuscitation and were without signs of other associated intraabdominal injuries on ultrasonogram and/or computed tomography. Patients were observed in an intensive care unit for at least 48 hours with repeated clinical assessments, laboratory studies, and bed rest. One patient with type 3 injury was operated on 8 days after injury because of sudden intraperitoneal bleeding on ambulation. Five patients required blood transfusions of not more than 300 mL per patient. Laboratory values returned to normal from 7 to 21 days after injury. Resolution of hepatic injury on ultrasonogram took from 1 to 3 months. Complete bed rest was prescribed for at least 10 days depending on the type of injury, with restricted activities up to 3 months postinjury. No complications were seen in this series.


Hirschsprung's disease: a possible cause of anastomotic failure following repair of intestinal atresia. Despite several reported cases, the association of Hirschsprung's disease and intestinal atresia is not widely recognized. We describe three patients with jejunoileal atresia who all had a preoperative barium enema that failed to show a transition zone. All three patients developed an anastomotic leak of the atresia repair, and required a temporary diverting enterostomy. Two patients had total colonic Hirschsprung's disease and in one, the transition zone was in the midtransverse colon. Histological examination of the appendix at the time of repair may be helpful in patients with small intestinal atresia. In patients who develop an anastomotic breakdown, rectal biopsy should be performed to rule out Hirschsprung's disease.


Anomalous congenital bands causing intestinal obstruction in children. The records of eight patients treated for intestinal obstruction resulting from bands that have no identifiable embryologic or acquired basis were reviewed retrospectively. All patients presented with symptoms and signs indicative of intestinal obstruction. Patients older than 2 years of age additionally had a history of chronic abdominal pain. One thick anomalous congenital band with blood vessels in it was found to be the cause of obstruction in each patient. Bands were located between ascending colon and terminal ileum in four patients (50%), ligament of Treitz and terminal ileum in two patients (25%), right lobe of liver and terminal ileum in one patient (12.5%), and right lobe of liver and ascending colon in one patient (12.5%). The obstructive mechanisms were compression of bowel by band in five patients (62.5%) and entrappment of an intestinal loop between the band and mesenterium in three patients (37.5%). These bands are suggested to be the anomalies of mesenterium that may cause intestinal obstruction and chronic abdominal pain in children.


Intussusception: prediction of outcome of gas enema. Gas has replaced barium as the preferred medium for enema reduction of intussusception in tertiary pediatric institutions. Previously, adverse clinical features that in combination predicted a low likelihood of successful reduction using barium had been identified and used to select patients suitable for attempted enema reduction. This study examines whether these adverse features are equally applicable to gas reduction of intussusception. For any given number of adverse features, gas enema reduction was found more likely to be successful than barium reduction and, in the absence of clinical evidence of peritonitis, multiple adverse features probably do not represent a contraindication to attempted gas enema reduction.


Acute appendicitis in children with leukemia and other malignancies: still a diagnostic dilemma. Of 6,099 children treated for malignancy, 16 (ages 3.5 to 18 years) developed acute appendicitis between 1962 and 1989. Fourteen had leukemia (ALL 10, AML 4). One each had rhabdomyosarcoma and Ewing's sarcoma. Active malignancy at diagnosis was noted in 10, 4 of whom had severe neutropenia (absolute neutrophil count less than 500/mm3). Of all the leukemics (2,794/6,099), abdominal pain during induction was a frequent complaint. The incidence of appendicitis, however, was low (0.5%). Nine of the 16 patients presented classically, facilitating prompt diagnosis and treatment. Six diagnoses were delayed. Three of these patients presented atypically with vague, nonlocalized pain, abdominal distention, lack of abdominal guarding, fever, dehydration, diarrhea, and unusual symptoms such as upper gastrointestinal bleeding. In each of these 6 patients the appendix was ruptured. Delays led to complications and deaths. Three patients required perioperative transfusions to treat excessive bleeding and two patients with ruptured appendicitis developed wound abscesses. Two patients died; in one, ruptured appendix was diagnosed only at autopsy. The other patient died of uncontrolled sepsis. Typhlitis occurring during induction chemotherapy may present similarly and is the main differential diagnosis. Typhlitis will usually improve with medical treatment alone. Nausea and vomiting (13/16), right lower quadrant pain (13/16), guarding (14/16), tachycardia (12/16), fever (10/16), and rebound tenderness (10/16) were the most frequent signs and symptoms of appendicitis. Persistent localized abdominal pain and guarding, lack of improvement with medical treatment, clinical deterioration, and the development of a mass were our indications for laparotomy. Despite major improvements in therapy, there is still a 37.5% error rate in our ability to accurately diagnose appendicitis in pediatric cancer patients.


Complications of surgical significance in pediatric renal transplantation. From 1969 to 1986, 303 renal allografts (290 cadaveric) were placed in 215 pediatric recipients. Twenty-three patients (7.6%) had renovascular complications and 16 (5.3%) had nonrenovascular complications. The overall incidence of surgically significant complications was 12.9%. Of these, 54% were felt to be of a technical etiology. The remainder were surgically significant in that their management necessitated operative intervention.


Single-system ectopic ureters: a review of 12 cases. Eight boys and 4 girls with single-system ectopic ureters were seen during a 15-year period. The abnormality was bilateral in 4 patients and the majority had major associated urological and other abnormalities. Eight ectopic ureters were reimplanted successfully into the bladder and 4 nonfunctioning kidneys were removed, as were 2 "blind" ectopic ureters. One patient died during the neonatal period and the others have been followed from 1 to 15 years. Renal function was noted to be normal in 10 patients and 1 has mild renal failure. Bladder function was normal in 8 patients. Early surgery should be undertaken in patients with single-system ectopic ureters. Stabilization of the upper urinary tract can be anticipated and satisfactory bladder function can also be expected in the majority of cases.


The ectopic ureterocele: a proposed practical classification based on renal unit jeopardy. A classification system for ectopic ureteroceles based on renal unit jeopardy is presented. This system has been found to be predictive of response to surgical reconstruction and is thus helpful in selecting the initial reconstructive approach. Specific guidelines for the selection of an appropriate surgical strategy are provided.


Evolution in the management of infant pyeloplasty. Improving diagnostic modalities, evolving concepts regarding perinatal renal physiology, and advances in surgical technique have contributed to an evolution in the management of infant pyeloplasties. Currently, the majority of patients present with a prenatal diagnosis of ureteropelvic junction obstruction and do not require surgical intervention prior to 4 weeks of age. Postnatal ultrasound, voiding cystourethrography, and nuclear renography complete the diagnostic evaluation, with intravenous urography and retrograde pyelography being unnecessary in the majority of infants. A decreasing incidence of complications and a shortening of hospital stay has been documented. We presently prefer a dismembered, nonintubated technique performed through a dorsal lumbotomy approach.


Intraoperative assessment of blood flow to strangulated stomach by pulse oximetry. A pulse oximeter was used to detect safe margins for resection of a strangulated stomach. The sensor probe was placed intraoperatively on various portions of the stomach, which herniated through a left lateral diaphragmatic defect. Failure to detect blood flow by this device in equivocally compromised tissue helped in the assessment of safe viable margins for resection.


Transcatheter embolization of a high-flow congenital intrahepatic arterial-portal venous malformation in an infant. An intrahepatic arterial-portal venous malformation (APVM) was diagnosed in a 4 1/2-month-old infant with portal hypertension. Visceral angiography showed a large saccular vascular space in the left hepatic lobe with a multiplicity of feeding arteries and drainage into the left portal vein. The lesion was successfully treated by transcatheter embolization following two unsuccessful surgical procedures. Two years later portal vein thrombosis with cavernous transformation was diagnosed, possibly a consequence of the high-flow arterial-portal shunt and its subsequent occlusion. Knowledge of the anatomic differences between this rare congenital APVM and the more commonly occurring arterial-portal fistula is crucial in planning effective transcatheter embolotherapy or surgery for these lesions.


Gastroduodenal duplication.

Gastroduodenal duplication. A newborn baby presented with a lump in the right hypochondrium. She had a bout of upper gastrointestinal bleeding. At operation, a pyloroduedenal duplication cyst was successfully removed. The relevant literature is reviewed.


Intestinal trichobezoar with perforation in a child. A 4-year-old girl presented with a history and examination results suggestive of peritonitis. Exploration of abdomen was done with suspicion of enteric perforation, which showed long ileal trichobezoar with perforation of .5-cm diameter. The stomach was devoid to any fragment of bezoar. There was no history of hair eating and nervous habits.


Nonsurgical therapy of splenic rupture in a hemophiliac. A boy with known hemophilia A sustained severe blunt abdominal trauma that caused major splenic rupture and hypovolemia. The administration of blood and aggressive clotting factor replacement therapy stabilized his course and he was successfully managed without resorting to operation.


An unusual case of pelviureteric junction obstruction. We describe an unusual case of pelviureteric junction obstruction in a child due to a benign ureteric polyp. Benign neoplasms of the ureter are uncommon in adults and extremely rare in children.


Augmented venous access in the problematic ECMO patient: a case report. Extracorporeal membrane oxygenation (ECMO) provides an adjunct to support of neonates with respiratory distress. The rate of venous drainage is the limiting step to the amount of arterial flow that may be generated during ECMO. We present a 3-kg, 37-week gestation female with congenital diaphragmatic hernia (CDH) whose anatomic venous drainage was insufficient to allow total extracorporeal support. The internal jugular vein was of insufficient size to allow placement of a cannula large enough to support adequate bypass flow. We established minimally acceptable flow by simultaneous caudad and cephalad catheterization of the internal vein. We performed a right lower quadrant retroperitoneal dissection and cannulated the common iliac vein when systemic pressures deteriorated at 24 hours with marginal venous drainage. After triple cannulation the bypass flows were normal. The right leg developed mild cyanosis and edema immediately following cannulation, but these changes resolved over 24 hours with elevation. The common iliac vein provides a desirable route for augmentation of venous drainage in the patient with difficult standard, or cephalad, jugular venous access for extracorporeal support.


Conservative management of splenic injury in infectious mononucleosis. Splenic rupture, in association with mononucleosis, can be lethal. Most reported cases of splenic rupture in patients with mononucleosis have not responded to conservative splenic preserving measures and have resulted in splenectomy. We report a case of traumatic splenic disruption in a patient with mononucleosis in whom conservative management was successful. We recommend consideration of splenic preservation measures in patients with mononucleosis and splenic disruption, if the patient is stable and meets other criteria of conservative management.


Effective early treatment of hepatic venoocclusive disease with a central splenorenal shunt in an infant. Venoocclusive disease of the liver (VOD) is a well-described complication following chemotherapy. It is manifested by jaundice and signs of portal hypertension and carries a mortality rate approaching 50%. There is no known treatment for the disease itself, although several recent reports suggest portacaval diversion may be effective in treating its sequelae. A 6.75-kg 8-month-old boy with VOD following bone marrow ablation and bone marrow transplantation (BMT) for juvenile chronic myelogenous leukemia (JCML) is presented. Over a 6-week period following bone marrow ablation he developed ascites refractory to diuretics, jaundice, and hematemasis with normal hepatocellular function. Splenectomy with a central splenorenal shunt was performed, which resulted in a significant reduction in portal pressures and complete resolution of his ascites and hematemasis without resultant encephalopathy. We propose that central end-to-side splenorenal shunting is an acceptable treatment for portal hypertension due to VOD and can be successfully performed in infants.


Optimum numerical integration methods for estimation of area-under-the-curve (AUC) and area-under-the-moment-curve (AUMC). Eleven numerical methods for estimation of AUC (including 4 new methods) and 22 methods for AUMC (including 8 new methods) were tested on large simulated noisy datasets representing bolus, oral and infusion concentration-time profiles. Some methods were unacceptable because their mean error was large; these included a commonly recommended form of the linear trapezoidal rule for AUMC. Others, notably Lagrange and cubic spline methods, were unacceptable because the variance of their estimates was large. These methods should be abandoned. A simple and easily programmed new method, parabolas-through-the-origin then log-trapezoidal rule, performed especially well.


Dynamics of drug distribution. I. Role of the second and third curve moments. Conventionally, the dynamics of distribution in the body is evaluated by the so-called distribution half-life (e.g., t1/2, alpha); but then the mean time of the distribution process is underestimated due to the influence of elimination. By contrast, information about the dynamics of distribution contained in drug disposition curves can be extracted by the second and third curve moments, parameters that are related to the variance (VDRT) and skewness (SDRT) of residence time distributions; whereas the equilibrium state characterized by the volume of distribution (Vss), is determined by the mean residence time (MDRT) or the first curve moment. The approach represents a general noncompartmental analysis that is independent of a detailed structural model or a particular disposition function. Two parameters are introduced to characterize the dynamics of drug distribution: (i) the degree of departure of the system from "well-mixed" behavior of instantaneous distribution equilibrium (related to VDRT) and (ii) the mean time until equilibration is achieved (mean equilibration time, MEQT), which additionally depends on SDRT. Both parameters are quantitative measures of the dynamics of distribution and display explicit physical significance in terms of distribution within the corresponding noneliminating system. It is further shown that the so-called "distribution phase" in biexponential disposition curves is related to a monoexponential mixing curve of its corresponding noneliminating system with an equilibration or mixing half-time, t1/2,M = t1/2,alpha (V beta/Vss*), where Vss* denotes the distribution volume of the noneliminating system. The results are applied to mixing and disposition curves measured for acetaminophen in liver-ligated and intact rats, respectively.


A computationally efficient approach for the design of population pharmacokinetic studies. A computationally efficient procedure was devised for designing experiments in which population pharmacokinetic parameters are estimated. The method, referred to as the large-sample approach, evaluates the variances of parameter estimates for a population pharmacostatistical model. The procedure utilizes the NONMEM program and requires a single simulation that assumes many, say 1000, subjects. The approach reduced CPU time by about a factor of 50 when compared with the evaluation of the same variances by the direct simulation of experiments. The large-sample and simulation approaches yielded generally similar values for the variances of parameter estimates. The variances calculated by the large-sample approach were, in the case of a simple model, close to the expected variances. The proposed method identified correctly the imprecise parameter estimates but somewhat underestimated their variances.


Evaluation of hypothesis testing for comparing two populations using NONMEM analysis. In a simulation study of inference on population pharmacokinetic parameters, two methods of performing tests of hypotheses comparing two populations using NONMEM were evaluated. These two methods are the test based upon 95% confidence intervals and the likelihood ratio test. Data were simulated according to a monoexponential model and, in that context, power curves for each test were generated for (i) the ratio of mean clearance and (ii) the ratio of the population standard deviations of clearance. To generate the power curves, a range of these parameters was employed; other pharmacokinetic parameters were selected to reflect the variability typically present in a Phase II clinical trial. For tests comparing the means, the confidence interval tests had approximately the same power as the likelihood ratio tests and were consistently more faithful to the nominal level of significance. For comparison of the standard deviations, and when the volume of information available was relatively small, however, the likelihood ratio test was more able to detect differences between the two groups. These results were then compared to results on parameter estimation in order to gain insight into the question of power. As an example, the nonnormality of estimates of the ratio of standard deviations plays an important role in explaining the low power for the confidence interval tests. We conclude that, except for the situation of modeling standard deviations with only sparse information, NONMEM produces tests of significance that are effective at detecting clinically significant differences between two populations.


Pharmacokinetic model for subcutaneous absorption of cyclosporine in the rabbit during chronic treatment. The objective of this study was to examine the concentrations in blood of cyclosporine (CyA) in rabbits during chronic subcutaneous (sc) administration and to propose a model that describes these data. Ten rabbits received sc CyA at 15 mg/kg daily for 1 week, then at 20 mg/kg twice weekly for 3 weeks, and at 15 mg/kg twice weekly for 7 weeks. Concentrations in blood were obtained weekly during the dosing period, and three to five concentrations were obtained over a 5-week period after dosing was terminated. CyA blood concentration-time (concentration in blood versus time) profiles could not be adequately described by absorption from a single dosing compartment. A two-compartment, sc absorption-site model was postulated. Steady-state concentrations in blood from three additional rabbits that had received CyA at 16.8 micrograms/min as a constant-rate intravenous infusion were added to the data set. A nonlinear mixed effects model was used to obtain the following parameter estimates (percent relative standard error): K12 = 0.111 day-1 (10.0), k21 = 0.0109 day-1 (12.6), ka = 0.0807 day-1 (11.8), CL/F = 14.6 L/day/kg (3.8), and Vd/F = 1.52 L/kg (13.4), where k12 and k21 are intercompartmental rate constants between sc compartments, ka is the absorption rate constant into the sampling compartment, CL/F is the apparent blood clearance of CyA from the body (F is bioavailability), and Vd/F is the apparent volume of distribution of CyA. The interindividual variability in CL/F was estimated as 20.5% (41.2), and the residual variability was 25.8% (15.6). The sc administration of CyA appears to provide slow, but very significant, absorption in rabbits.


A critical evaluation of the present status of toxicity of aminoxyl radicals. The literature on the toxicity of aminoxyl radicals was critically reviewed. It was concluded that, in general, the aminoxyl radicals possess a very low toxicity and are not mutagenic. In support of this contention, several aminoxyl radicals were evaluated in vitro. Thus, aminoxyl radicals 3-carboxy-2,2,5,5-tetramethylpyrroline-1-oxyl (1), 3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCA; 2), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol;3), and N-(1-hydroxymethyl-2,3-dihydroxypropyl)-3-carboxyamino-2,2,5,5- tetramethylpyrrolidine-1-oxyl (NAT; 4) were evaluated using Salmonella typhimurium tester strains TA 102 and TA 104, with a supplement of xanthine oxidase enzyme. 1, 2, and 4 were found to be nonmutagenic, while 3 elicited in TA 104 only about a twofold increase in the number of revertants above the control. This response is considered to be, at best, marginal in view of wide fluctuations of experimental scores. The results of the present study are in agreement with those of other studies confirming the nonmutagenicity of aminoxyl radicals investigated to date. However, these conclusions are different from those of a study where 3 was tested in the presence of a generated toxic oxygen species that can cause mutagenic changes of the environment.


Influence of higher rates of agitation on release patterns of immediate-release drug products. The dissolution procedure serves as a quality control test to assure batch-to-batch uniformity and bioequivalence of a product once the bioavailability of the product has been established. It can also be used to detect manufacturing and/or process variations that could reduce product bioavailability. Dissolution testing must be conducted at an appropriate agitation rate. Tests conducted at high agitation rates may lose the ability to differentiate between good and bad products. Although the effect of high agitation rates has been known for some time, several immediate-release drug products still have United States Pharmacopeia (USP) monograph dissolution procedures that require very high agitation rates. A systematic survey was conducted on marketed tablets of chloroquine phosphate, griseofulvin, hydroxychloroquine sulfate, isocarboxazide, primaquine phosphate, and sulfadiazine. Each of these products has a USP monograph requiring a dissolution test at a paddle speed of 100 rpm. To study the influence of agitation rate on the dissolution rate of these products, dissolution studies were conducted at paddle speeds of 50, 75, and 100 rpm with the USP apparatus 2 (paddle method). The dissolution rate increased with an increase in the agitation rate from 50 to 75 rpm. However, no significant increase in the dissolution rate was noted with an increase in the agitation rate from 75 to 100 rpm. The data support the position that the higher agitation rate of 100 rpm is not necessary for a quality control procedure or a compendial standard for the products tested.


Quantitative prediction of transdermal iontophoretic delivery of arbutamine in humans with the in vitro isolated perfused porcine skin flap. The use of the isolated perfused porcine skin flap (IPPSF), an alternative in vitro animal model, to predict the profile of the concentration of arbutamine in plasma samples from humans after transdermal iontophoretic administration of this novel catecholamine is described. The strategy involved administering the drug in the IPPSF (n = 8) and assaying concentrations of drug in the venous efflux versus time (IPPSF venous efflux profile). Intravenous infusion (n = 7) and transdermal studies (n = 32) were also conducted in humans. The IPPSF profile was then used as an input into an intravenous pharmacokinetic model obtained from the human experiments to predict the profile of concentration of drug in plasma versus time (plasma concentration-time profile) seen after iontophoretic administration. The IPPSF profiles were denormalized according to the parameters used in the human studies (i.e., multiplied by in vivo concentration, electrode area, current, and dosing time). For two different sets of iontophoretic dosing conditions, the concentration-time profiles that were predicted on the basis of the IPPSF study were compared with those seen after delivery to humans.


Hydroxypropylcyclodextrins in parenteral use. I: Lipid dissolution and effects on lipid transfers in vitro. Hydroxypropyl ethers of cyclodextrins form water-soluble inclusion complexes with lipids. Of the three hydroxypropylcyclodextrins examined, hydroxypropyl-alpha-cyclodextrin had limited specificity for phospholipids, and hydroxypropyl-beta-cyclodextrin had limited specificity for cholesterol, and hydroxypropyl-gamma-cyclodextrin was nonspecific. The formation of inclusion complexes was found to be a fast and reversible process in which complexation of cholesterol did not inhibit its oxidation by cholesterol oxidase, and cholesterol of the erythrocyte membrane could be exchanged within a minute for cholesteryl methyl ether which was in the inclusion complex. Thus, hydroxypropylcyclodextrin in the circulation may catalyze the transport of lipids in the direction of equilibrium distribution.


Hydroxypropylcyclodextrins in parenteral use. II: Effects on transport and disposition of lipids in rabbit and humans. Hydroxypropyl ethers of cyclodextrins, after parenteral administration, come into contact with lipids in tissues and in circulation and form water-soluble inclusion complexes with these lipids. A single intravenous administration of hydroxypropyl-beta-cyclodextrin to a hereditary hyperlipidemic Watanabe rabbit slightly and temporarily decreased the level of total cholesterol in serum. Single injections of hydroxypropyl-alpha-cyclodextrin and of the corresponding gamma-homologue, both of which are less potent solubilizers of cholesterol, had lesser effects. Repeated administration of hydroxypropyl-beta-cyclodextrin to rabbits led to a gradual increase in total cholesterol in circulation and eventually to a slight relief of atherosclerotic lesions in the thoracic aorta. The only untoward effects of repeated treatments (total doses of up to 40 g/kg) were vacuoles in cells of proximal convoluted tubules in the kidneys. Repeated administration also strongly increased cholesterol in urine, probably because of excretion of the soluble cholesterol-hydroxypropyl-beta-cyclodextrin complex. Proteins in urine increased significantly, whereas triglycerides increased only moderately after repeated administrations. Intravenous infusion of hydroxypropyl-beta-cyclodextrin into a patient with hypervitaminosis A led to a release of liver-stored retinoids into serum in quantities much higher than those that could be directly solubilized by hydroxypropyl-beta-cyclodextrin. Levels of total cholesterol in the circulation of this patient decreased during the infusion. Thus, hydroxypropylcyclodextrins may serve as artificial lipid carriers in the circulation, and because the exchanges that involve inclusion complexation occur very quickly, the presence of hydroxypropylcyclodextrins in organisms may catalytically augment the establishment of equilibria in lipid distribution.


Concanavalin A microspheres for a self-regulating insulin delivery system. A self-regulating insulin delivery system based on the competitive binding of glucose and p-succinylamidophenyl-alpha-D-glycopyranoside-insulin (SAPG-insulin) to crosslinked concanavalin A (Con A) microspheres (MSs) has been investigated. Con A MSs prepared by a water-in-oil emulsion technique demonstrated properties of binding to glucose and SAPG-insulin (binding constants of 1.25 x 10(3) and 1.28 x 10(4) M-1, respectively) that are similar to the literature values of these properties for unmodified Con A. The retained binding capacity (number of binding sites per molecule) of Con A MSs, produced with 20% of the epsilon-amino groups crosslinked, was approximately 28% that of intact Con A. As a new device, Con A MSs loaded with SAPG-insulin was enclosed in a heat-sealed, surface-modified, porous poly(vinylidene difluoride) membrane pouch. This system showed a pulsatile release pattern for insulin with a short lag time in response to glucose challenges of 50-500 mg/dL. The pattern of release of SAPG-insulin from the devices was studied with varying design parameters, such as surface area, membrane pore size, and loading content of SAPG-insulin.


Preparation and evaluation of Eudragit gels. III: Rectal gel preparations for sustained release of pentoxifylline. A novel method was established for the preparation of Eudragit S, Eudragit L, and Eudispert high-viscosity (hv) hydrogel and xerogel preparations containing a medicinal component such as pentoxifylline (an agent that improves cerebral microcirculation). A significant correlation was found between the in vitro mean dissolution time and the in vivo mean residence time of pentoxifylline after rectal administration of these preparations in rabbits. Staying properties of the hydrogel and xerogel preparations in the lower part of the rectum were compared with those of polyethylene glycol 2000 and Witepsol S-55 suppositories in rats, with water-insoluble dye. Eudispert hv hydrogel and xerogel preparations have excellent staying properties in the rectum. The efficacy of Eudispert hv xerogel preparations may be reduced by first passage through the liver after oral administration.


Comparative bioavailability of a sustained-release ion-exchange hydralazine product with a potassium (cation) challenge. A sustained-release formulation of hydralazine was manufactured by binding hydralazine to an ion-exchange resin and coating the drug-resin complex with a semipermeable membrane. Because the sustained-release characteristics are due in part to displacement of drug from the drug-resin complex by gastrointestinal ions, the stability of the sustained-release formulation could be compromised if challenged by a high concentration of ions. In this study, 12 healthy male volunteers participated in a two-way crossover trial that was designed to test the bioavailability and release of drug from the sustained-release formulation both with and without concomitant ingestion of a solution of KCl. Blood samples were collected over a 14-h period after administration of either treatment. Analysis of whole blood for hydralazine and comparison of the values of the area under the curve of the concentration of hydralazine versus time, the maximum concentration of hydralazine, and the time to reach the maximum concentration between the two experimental groups showed that KCl had no influence on the bioavailability or release characteristics of hydralazine from the sustained-release formulation.


Interaction of opiate molecules with lipid monolayers and liposomes. The interaction of opiate molecules (buprenorphine, codeine, dextromethorphan, diprenorphine, etorphine, meperidine, methadone, morphine, and naloxone) with lipids (phosphatidylcholine, phosphatidylinositol, phatidylinositol, phosphatidylserine, and cholesterol) by using liposomes and monomolecular layers as membrane models is described. The ability of opiates to induce leakage of carboxyfluorescin from liposomes is highly dependent on the hydrophobicity of the opiate molecules. Buprenorphine and etorphine increased the membrane permeability in all the experiments. On the contrary, naloxone, morphine, and codeine only caused a slight release of the entrapped dye in the presence of acidic phospholipids. Moreover, the leakage of carboxyfluorescein is directly related to the concentration of drug in the incubation media. Studies of the kinetics of the surface penetration of these molecules into monolayers of phospholipids were performed. Again, in this system, buprenorphine and etorphine exhibited stronger interactions than the most hydrophilic opiates. Nevertheless, in these experiments, differences among the opiate molecules are not so high as in the liposomes. The time course of the penetration of all of these molecules in the monolayers fits the Lineweaver-Burk equation. This fact suggests a lack of specific interactions and the predominance of hydrophobic factors. Moreover, the high percentage of release of entrapped dye caused by some opiate molecules suggests a possible toxic side-effect for these agents.


Novel approach to estimate quality of binary random powder mixtures: samples of constant volume. I: Derivation of equation. An equation of the quality of binary random mixtures that applies to powder samples of constant bulk volume was derived from the binomial distribution. In contrast to the Stange-Poole equation for samples of constant mass, this approach can also be used for constituents with large differences in particle size and in bulk density. The validity of this equation was verified with tablets directly compressed from mixtures composed of equal mass proportions of sucrose [volume-weighted/volume-number mean diameter (dv), 504 microns] as the coarse ingredient (A) and of a microcrystalline cellulose (Avicel PH 101)-talc mixture (dv, 60 microns) as the fine constituent (B). Because of the difference in the bulk densities of A and B, the equation estimated a coefficient of the random content variation, which for A was double that for B. The content variations found with the tablets were in excellent agreement with the calculated values and reflected the differences predicted from theory. The Stange-Poole equation yielded identical values of the content variations of A and B, which is in contrast to the experimental results.


Quinidine as a muscarinic antagonist: a structural approach. The synthesis, spectroscopic characteristics, and single-crystal X-ray structural analysis of quitenidine methyl ester monohydrate, a derivative of the muscarinic antagonist quinidine, are presented. Quitenidine methyl ester monohydrate (C20H24N2O4.H2O) crystallizes in the orthorhombic space group P2(1)2(1)2(1), with a = 16.69(3) A, b = 12.46(2) A, c = 9.70(1) A, and Z = 4. The crystal structure was refined to a discrepancy factor (R) of 0.097. Substitution of the quinidine vinyl chain with a carboxymethyl group does not influence the conformation. The carboxymethyl group is positionally disordered, a fact that complicates refinement of the structure. The water molecule is bonded to the quinuclidine nitrogen atom, and the hydroxyl group forms an intermolecular hydrogen bond with the quinoline nitrogen atom. The molecular structure of the ester was compared with those of quinidine, quinine, and four other antimuscarinic agents. An approximately linear relationship between the distance from the nonaromatic nitrogen to the plane of the aromatic part of the molecules and the blocking potency of these agents was noted; the greater this distance, the more potent is the antagonist.


Acid-base properties of pristinamycin IA and related compounds. The pKa values of acid-base equilibria involved in the protonation of pristinamycin IA and its model compound, N-isobutyl-3-hydroxypicolinamide, were determined by UV-visible absorption spectrometry and potentiometric titration. The equilibrium between dipolar ionic and uncharged neutral forms was investigated spectrometrically in methanol-water solutions. With pristinamycin IA, the dipolar ionic form predominated in aqueous solutions buffered to the isoelectric pH. The effects of structure on the ionization constants are briefly discussed.


External-standard high-performance liquid chromatographic method for quantitative determination of furosemide in plasma by using solid-phase extraction and on-line elution. A rapid and simple external-standard high-performance liquid chromatographic (HPLC) method has been developed for the determination of the concentration of furosemide in plasma. The analyte is extracted with a C-2 ethyl sorbent. On-line elution of the analyte into the HPLC system is accomplished with an advanced automated sample processor (Varian). Furosemide is quantified by fluorescence detection within a linear range of 25 to 1000 ng/mL (average correlation coefficient, 0.9998), with a limit of detection of 1.8 ng/mL. Both internal- and external-standard procedures were evaluated, and the external-standard procedure demonstrated superior characteristics. The external-standard procedure was precise to within a relative standard deviation of 8% and accurate with less than 3% error throughout the concentration range studied. The external-standard HPLC method was used to analyze the concentration of furosemide in greater than 1000 plasma samples obtained from patients with either normal kidney function or renal failure who had received furosemide either orally or intravenously in an experimental setting.


Isolation and solid-state characteristics of a new crystal form of indomethacin. A new polymorphic crystal form of indomethacin was precipitated from an aqueous solution of indomethacin and beta-cyclodextrin by titration with a 0.5 N HCl aqueous solution. Three polymorphs (alpha, beta, and gamma forms) and a new crystal form were differentiated with thermal analysis, infrared spectroscopy, powder X-ray diffractometry, thin-layer chromatography, elemental analysis, and Fourier transform infrared (FTIR) spectroscopy with a newly developed FTIR microscope equipped with a thermal analyzer. The new crystal polymorph of indomethacin exhibited endo- and exothermic peaks near 102.8 and 104.1 degrees C, respectively, because of phase transitions without weight loss, followed by two additional endothermic peaks at 151 and 158.9 degrees C, because of fusion. The differential scanning calorimetry-FTIR system can be used to examine the correlation between structural change of C = O stretching bands of this new polymorph and its thermal response. The new crystal form contained some gamma-form crystals, determined with an FTIR microscope equipped with a mapping option. Solid-state carbon-13 nuclear magnetic resonance spectra of the polymorphs of indomethacin were also examined.


High-performance liquid chromatographic determination of the pi values of azol-N-yl substituents. The pi (hydrophobic constant) values for 16 parent azoles (pyrrole, imidazole, pyrazole, four triazoles, two tetrazoles, indole, benzimidazole, 1H- and 2H-indazoles, 1H- and 2H-benzotriazoles, and carbazole) were calculated from the logarithms of the capacity factors (log k') determined by HPLC. The values thus obtained are discussed according to an additive model in which the number and position of pyridinelike nitrogen atoms and the annelation effect are considered.


Synthesis and inotropic activity of pyrazolo[4,3-c]pyridine-4-ones and related compounds. Two series of 3,6-dimethyl-1-phenyl-1H-pyrazolo[4,3-c] pyridine-4-ones (5-9) and 3,6-dimethyl-1-phenyl-1H-pyrazolo[4,3-c] pyridine-4-thiones (11-13) were prepared from dehydroacetic acid as starting material and evaluated for positive inotropic activity in vitro. Moreover, the activity of the synthesized compounds was compared with that of mirlinone as a reference. Among these compounds, the positive inotropic activity of 8a, 11a, and 12 were approximately 1.24, 1.77, and 1.11 times more potent, respectively, than that of mirlinone.


Degradation kinetics and mechanisms of moricizine hydrochloride in acidic medium. The degradation kinetics of moricizine hydrochloride (1) were examined over a pH range of 0.6 to 6.0 at an ionic strength of 0.3 and 60 degrees C. The disappearance of intact 1 was followed by a stability-indicating HPLC assay. The degradation products, which had approximate solubilities of less than 100 micrograms/mL, precipitated in aqueous solution. The precipitate was collected for HPLC analysis and identification of degradation products. Degradation of 1 was catalyzed by acetate and phosphate buffers and was pH dependent, with the pH of the minimum rate constant located between 2.8 and 3.2. At pH 0.6-2.0, 1 degraded via amide hydrolysis to yield first ethyl (10H-phenothiazin-2-yl) carbamate (2), an amide hydrolysis product, which further oxidized in parallel to give ethyl (3-oxo-3H-phenothiazin-2-yl) carbamate (3), ethyl (10H-phenothiazin-2-yl) carbamate S-oxide (4), and diethyl (3,10'-bi-10H-phenothiazine-2,2'-diyl)bis(carbamate) (5), the dimer of the amide hydrolysis product. At pH 2.2-6.0, 1 degraded via a reverse Mannich reaction, to form the reverse Mannich product ethyl [10-(1-oxo-2-propenyl)-10H-phenothiazin-2-yl] carbamate (6), and by parallel reaction via the described amide hydrolysis pathway. The dimer of the amide hydrolysis product was not detectable at pH greater than 2.8. At pH greater than 4.0, the reverse Mannich product was the predominant degradation product. Degradation of 1 was subject to positive and negative kinetic salt effects at pH 1.0 and 4.0, respectively. Arrhenius plots determined at pH 1.0 and 6.0 were linear between 37 and 70 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)


Evaluation of thermodynamic ionization constants by computation of spectrophotometric and potentiometric experimental data obtained simultaneously from a flow system. A method is proposed for the direct and simultaneous determination of the thermodynamic ionization constants of bifunctional substances, with (microscopic) and without overlap in the ionizations, with computational treatment of spectrophotometric and potentiometric experimental data obtained simultaneously in a flow system. For monofunctional substances, potentiometric data are enough. The data are obtained at very low values of ionic strength, which is variable throughout the experiment because no inert electrolyte is added. The MICROTER program, written in FORTRAN 77, is based on an algorithm of mathematical optimization with a controlled-descent movement. The ionization constants of the following substances of pharmacological interest were determined: cysteine, penicillamine, ofloxacin, and norfloxacin (bifunctional with overlap); cephalexin and cephapirin (bifunctional without overlap); and tolazoline, naphazoline, and oximetazoline (monofunctional).


Characterization of a synthetic peptide impurity by fast-atom bombardment-tandem mass spectrometry and gas chromatography-mass spectrometry. Fast-atom bombardment-tandem mass spectrometry (FAB-MS-MS) was used to characterize the structure of atosiban, a synthetic oxytocin antagonist, and one of its synthesis-related impurities. The nature of the structural modification in the impurity of interest, replacement of the proline residue by 5-aminovaleric acid, was determined directly from its product ion MS-MS spectrum. Confirmation of the identity of the impurity was accomplished with GC-MS.


Flows of liquid and electrical current through monolayers of cultured bovine arterial endothelium. 1. Monolayers of arterial endothelium on porous membranes were exposed to a constant pressure between 15 and 35 cmH2O. The rates of liquid flow per unit area (Jv/A) through the monolayers were monitored, together with the electrical resistance (Rm) of the endothelium. 2. At constant pressure, Jv/A decreased with an approximately exponential time course, towards a stable baseline value. This behaviour resembles the sealing previously described for cultured vascular endothelium. At 30-35 cmH2O and 37 degrees C, the mean (+/- S.E.M.) half-time (t1/2) of the decrease in Jv/A (the sealing t1/2) was 548 +/- 141 S (n = 5). The difference between the initial and baseline values of Jv/A was expressed as a fraction of the initial value. The mean (+/- S.E.M.) of this sealing fraction was 0.64 +/- 0.03 (n = 5). Mean (+/- S.E.M.) hydraulic permeability (Lp) was 23.9 +/- 6.4 x 10(-7) cm S-1 cmH2O-1 (n = 9), when measured after sealing. Endothelium appeared damaged after sealing at 30-35 cmH2O and 37 degrees C. 3. Sealing was also observed using glutaraldehyde-fixed endothelium at 30-33 cmH2O and 26-28 degrees C. There was no significant difference between the mean sealing t1/2 of these fixed monolayers, and that of unfixed endothelium at 30-35 cmH2O and 37 degrees C. However, mean sealing fraction was significantly larger for the fixed monolayers than for unfixed endothelium at 30-35 cmH2O and 37 degrees C. There were no significant difference between the post-sealing Lps of these fixed and unfixed monolayers, although the fixed monolayers appeared undamaged after sealing. 4. For unfixed endothelium, Rm was lower after sealing at 30-35 cmH2O and 37 degrees C than before pressure application. There was no significant difference between endothelial Rm before and after sealing, for glutaraldehyde-fixed monolayers. 5. Sealing was also observed at 0 degree C, using unfixed endothelium at 30 cmH2O. Mean sealing t1/2 was not significantly different from that of unfixed endothelium at 30 cmH2O and 37 degrees C. However, mean sealing fraction was significantly smaller at 0 degree C than at 37 degrees C. Unfixed endothelium appeared undamaged after sealing at 30 cmH2O and 0 degree C. Despite this, the post-sealing Lp was not significantly different from that of unfixed endothelium sealed at 30 cmH2O and 37 degrees C, after allowance was made for the effect of temperature on Lp. Rm was not measured in these experiments. 6. It is proposed that sealing is due to pressure-induced deformation of monolayers.(ABSTRACT TRUNCATED AT 400 WORDS)


Muscarinic responses of rat basolateral amygdaloid neurons recorded in vitro. 1. Intracellular recordings were obtained from pyramidal-type neurons in the basolateral amygdaloid nucleus (BLA) in slices of rat ventral forebrain and used to compare the actions of exogenously applied cholinomimetics to the effects produced by electrical stimulation of amygdalopetal cholinergic afferents from basal forebrain. 2. Bath application of carbachol depolarized pyramidal cells with an associated increase in input resistance (Ri), reduced the slow after-hyperpolarization (AHP) that followed a series of current-evoked action potentials and blocked spike frequency accommodation. All of these effects were reversed by the muscarinic antagonist atropine but not by the nicotinic antagonist hexamethonium. 3. Electrical stimulation of amygdaloid afferents within the external capsule evoked a series of synaptic potentials consisting of a non-cholinergic fast excitatory postsynaptic potential (EPSP), followed by early and late inhibitory postsynaptic potentials (IPSPs). Each of these synaptic potentials was reduced by carbachol in an atropine-sensitive manner. 4. Local application of carbachol to pyramidal cells produced a short-latency hyperpolarization followed by a prolonged depolarization. The hyperpolarization and depolarization to carbachol were blocked by atropine but not hexamethonium. 5. The carbachol-induced hyperpolarization was associated with a decrease in Ri and had a reversal potential nearly identical to that of the early IPSP. The inhibitory response was blocked by perfusion of medium containing tetrodotoxin (TTX), bicuculline or picrotoxin, while the subsequent depolarization was unaffected. On the basis of these data, it is concluded that the muscarinic hyperpolarization is mediated through the rapid excitation of presynaptic GABAergic interneurons in the slice. 6. The findings that the carbachol-induced depolarization was associated with an increase in Ri, often had a reversal potential below -80 mV, was sensitive to changes in extracellular potassium concentration and was blocked by intracellular ionophoresis of the potassium channel blocker caesium suggest that it resulted from a muscarinic blockade of one or more potassium conductances. 7. Repetitive stimulation of sites within the slice containing cholinergic afferents evoked a series of fast EPSPs followed by IPSPs. These non-cholinergic potentials were followed by a slow EPSP that lasted from 10 s-4 min. The slow EPSP was enhanced by eserine and blocked by atropine. It was also blocked by TTX or cadmium, indicating that it was dependent on spike propagation and calcium-dependent release of acetylcholine (ACh). 8. Stimulation of cholinergic afferents in the slice mimicked other effects produced by carbachol including blockade of the slow AHP and accommodation of action potential discharge and these actions were potentiated by eserine and blocked by atropine.(ABSTRACT TRUNCATED AT 400 WORDS)


Factors affecting movement of excitatory substances from pulmonary capillaries to type J receptors of anaesthetized cats. 1. Using phenyl diguanide (PDG) as an excitatory substance, the role of certain factors that could influence the movement of such substances across the pulmonary capillaries to the J receptors was studied in cats anaesthetized with sodium pentobarbitone. This was aided by using a new method for estimating continuously in vivo the concentration (C) of PDG in the blood of the pulmonary artery. 2. Reduction of pulmonary blood flow by partial occlusion of the inferior vena cava enhanced the responses of the J receptors to PDG significantly in twelve out of thirteen trials. These effects, which occurred at a time when pulmonary capillary pressure (PCP) had fallen, could be related to the increase in the estimated mean C of PDG over the first 3 s or to the C t (concentration x time) area to 50% of peak C. The responses bore no relation to peak C or rate of rise of C. 3. The responses of the receptors to PDG increased significantly after three out of eight injections of PDG while the PCP was raised by partial occlusion of the mitral orifice; reduced responses were recorded after two injections. These results, showing relatively much weaker stimulation by PDG in spite of the enhanced level of J receptor excitability produced by the raised PCP itself, suggest that movement of PDG out of the capillaries to the J receptors must be influenced primarily by forces governing diffusion, not filtration. 4. In addition to C of PDG there appear to be other factors that influence the responses of the receptors to PDG.


Transmucosal electrical resistance in rabbit isolated gastric mucosa during exposure to acid. 1. Transmucosal electrical resistance (Rt) and short-circuit current (Isc) were determined in rabbit isolated fundic mucosa. Under basal conditions, with a HCO(3-)-free HEPES-buffered solution (pH 7.4) bathing both sides of the mucosae, Rt was 161.5 + 5.0 omega cm2 and Isc 41.8 +/- 1.8 microA cm-2, and these values were not significantly different to values observed in HCO(3-)-buffered Krebs-Hensleit solution. 2. The basal Isc was inhibited by the Cl- channel blocker diphenylamine-2-carboxylate, and ouabain, but unaffected by the Na+ channel blocker amiloride (10(-5) M), consistent with electrogenic chloride secretion dependent upon a sodium gradient. Prostaglandin E2 (10(-7) M) stimulated an increase in Isc which was susceptible to inhibition by diphenylamine-2-carboxylate, but not amiloride, again consistent with Cl- secretion. 3. Stepwise acidification of the mucosal solution to pH 2.8 resulted in an increase in Rt of 43%, as compared with that measured with mucosal pH 7.4. Isc did not change during the acidification to pH 2.8, indicating retention of tissue viability. Increased Rt while Isc remained constant is consistent with an acid-induced decrease in the shunt (paracellular) conductance in this Cl(-)-secreting tissue. At pH less than 2.8, Rt declined rapidly and Isc declined and reversed, consistent with H+ back-diffusion. Scanning electron microscopic investigation of tissue exposed to mucosal pH 2.8 revealed little difference from control (pH 7.4) tissue, but there was considerable evidence of cellular damage and membrane disruption in tissue exposed to pH 1.8. 4. Acidification of the serosal solution did not increase Rt, which was maintained until pH 3.7, and then rapidly declined at pH less than 3.7. Bilateral acidification produced a mixed response; Rt increased, as for mucosal acidification, down to pH 2.8, after which there was a rapid decline in Rt following the pattern observed for serosal acidification. 5. Compared at a mucosal pH approximately 2.8, DIDS (4 x 10(-4) M) and amiloride (10(-3) M) inhibited the acid-induced increase in Rt, suggesting a role for both Cl(-)-HCO3- and Na(+)-H+ exchange in the response. In contrast, the acid-induced increase in Rt was unaffected by a lower concentration of amiloride (10(-5) M), acetazolamide and ouabain. Therefore, neither Na+ channels nor a Na+ gradient appear to be involved in the acid-induced increase in Rt.(ABSTRACT TRUNCATED AT 400 WORDS)