The relationship between mind, brain, and seizures. The medical model of epilepsy suggests that seizures arise at random or in response to precise physiological events. Little weight is given to the part that ongoing brain activity may play in either precipitating or inhibiting seizures. In the focal epilepsies, the presence of damaged neurons that fire in the epileptic mode continuously and are called pacemaker cells has been demonstrated in both animal models and human epilepsy. If these pacemaker cells are firing all the time, why then do seizures arise only spasmodically? Behavior can be thought of as changes in the excitation and inhibition of populations of neurons. Therefore, it is likely that these excitatory and inhibitory waves will either increase or decrease the likelihood of seizures arising. The conditioning of the neurons to fire in volleys in a biofeedback paradigm, the conditioning of seizures in a classic Pavlovian sense, and the occurrence of seizures in response to behavioral changes has been shown in animal models of epilepsy and in humans. There is now evidence that children can both inhibit and generate their own seizures spontaneously. Many adult patients have behavioral strategies that they use either to inhibit or to stop the spreading seizures. In patients who have difficulties in coping with the stresses in their life, the voluntary generation of seizures may come to form a response to difficult situations. Thus, any complete epilepsy program must consider the patient, the behavior, and the relationship between seizures and behavior.


Cognitive correlates of interictal discharges. Interictal discharges can occur silently without apparent simultaneous clinical manifestations. Nevertheless, formal testing during electroencephalographic (EEG) recording may demonstrate transitory cognitive impairment (TCI). The probability of demonstrating TCI is related to the nature of the test employed and the type of epileptiform discharge. Difficult tasks are more useful to detect TCI, and working memory and language tests may be particularly sensitive. Generalized 3-Hz spike-wave bursts lasting at least 3 s are most likely to produce demonstrable TCI, but they can also be found during briefer and even focal discharges. The latter exhibit some specificity: left-sided focal spiking more frequently produces errors in verbal tasks, whereas right-sided discharges are more often accompanied by impairment in handling nonverbal material. TCI may adversely affect the patient's psychosocial functioning in daily life, as has been shown by some studies pointing out an impairment of educational skill in epileptic children and of driving performance in motorists. Our study on benign childhood epilepsy with Rolandic spikes also detected TCI in the majority of the patients. Nevertheless, it is not possible to claim that everyone with subclinical EEG discharges has TCI that adversely affects their psychosocial functioning. It may be possible to treat TCI by antiepileptic drugs.


Everyday memory failures in people with epilepsy. In a series of studies, we have explored the nature of memory problems experienced by people with epilepsy. By means of a questionnaire, the first study surveyed everyday memory failures experienced by 742 people with epilepsy. Findings revealed a high level of failures that were associated with later age of onset of seizures and raised levels of anxiety and depression. A second smaller prospective study confirmed these findings and suggested that patients with epilepsy had underestimated the frequency of memory complaints when assessed retrospectively. The third study investigated the relationship between self-reported memory failures and neuropsychological test performance. A measure of verbal recall was the best predictor of reported memory failures. Again, older age of onset and mood were found to be pertinent variables in relation to memory complaints.


Epileptic amnesic syndrome.

Epileptic amnesic syndrome. Thirteen patients with "epileptic amnesic syndrome" (EAS) presented with adult-senile onset of a severe memory complaint that started before or at the same time as seizures. All were diagnosed as temporal lobe epilepsy (TLE). The seizures were stereotyped, with only short loss of contact and oral automatisms, and because they were not obvious or disturbing, they remained underdiagnosed for a long time. Nine cases also presented attacks of transient anteroretrograde amnesia after the seizures--called "epileptic amnesic attacks" (EAA)--during which the patients were able to perform complex actions. EAA are similar to the attacks of transient global amnesia (TGA) but are more frequent, shorter, accompanied by clear-cut clinical and electroencephalographic epileptic manifestations, and respond favorably to antiepileptic therapy. Neuropsychological investigation ruled out global mental deterioration, showing only selective memory impairment in a few long-term tasks and dissociation between formal findings and the relevant memory complaint. These cases have uniform anamnestic, clinical, and neuropsychological characteristics and represent a particular clinical expression of TLE, namely EAS. We suggest that an epileptic origin be entertained in patients presenting repeated amnesic attacks resembling TGA or who complain of persistent memory disturbance, after more common etiologies have been excluded.


Problems in the assessment of cognitive effects of antiepileptic drugs. The major problems in the study of the cognitive effects of antiepileptic drugs (AEDs) are explored. These problems include subject selection factors, statistical difficulties, matters pertaining to choice of cognitive tests, and the impacts of seizures on performance. A tendency is noted for these contaminating factors to result in attributing to AEDs adverse changes that might more accurately be related to other causes. Although all of these active central nervous system medications likely have some adverse cognitive effects, at least at high levels, the magnitude of these effects may have been exaggerated in the past. This is confirmed by more recent and better-controlled investigations.


Antiepileptic drugs and their psychotropic effects. Antiepileptic drugs (AEDs) are still the main treatment for epilepsy. The first drugs such as the bromides, phenobarbital (PB), and related barbituates were all found to be anticonvulsant by chance. They also all carried to some extent the disadvantages of slowing thinking and motor behavior. Bromides are now seldom used and (PB) is only used when other drugs fail, although it is an important drug in the third world because of its low cost. Carbamazepine (CBZ), valproate (VPA), and phenytoin (PHT) are the current first-line AEDs. All of these drugs vary in the extent of their effect on mood. These drugs have also all been used in the treatment of psychiatric disorders. CBZ has been used mainly as a mood normalizer and has had some success in treating hypermanic episodes. VPA has been used successfully in the treatment of cyclical psychoses, whereas PHT, although it had a vogue in the 1940s for the treatment of psychosis, is little used as a psychological treatment now.


Antiepileptic drugs and memory.

Antiepileptic drugs and memory. Assessing the effects of medication on cognitive functions including memory is fraught with methodological problems. This article illustrates the range of approaches that have been employed. Medication effects have been more readily demonstrated in patients with intractable epilepsy, in whom drug dosages are higher and the risk of polytherapy is greater. Newly diagnosed cases and individuals treated with monotherapy show fewer effects. Evaluation of memory functions in most studies has been very limited, and where effects have been recorded these may well be secondary to changes in attentional level or mental processing speed.


Cognitive effects of antiepileptic drug discontinuation. We studied the cognitive effects of antiepileptic drugs (AEDs), by investigating epileptic patients who were seizure-free for a long time and who were undergoing fixed monotherapy. Ninety patients [27 with phenobarbital (PB), 18 with carbamazepine (CBZ), 16 with phenytoin (PHT), and 29 with valproate (VPA)] were examined by a neuropsychological battery exploring intelligence, vigilance, attention, memory, and visuomotor performances at full AED dose (T1) and compared to 28 normal volunteers. We also evaluated the effects of AED discontinuation by retesting patients 3 months after reduction at half drug dose (T2) and 3 months (T3) and 1 year (T4) after complete discontinuation. Our findings showed that patients receiving CBZ did not differ from controls at any time of examination. Patients receiving PB had significant differences only at T1 (visuomotor performance and immediate spatial memory). Patients receiving VPA showed differences in attention, visuomotor performance, verbal span and sensory discrimination tasks at T1, in visuomotor performance at T2 and in spatial span at T3, whereas no differences were detected at T4. Patients receiving PHT had a difference in intelligence and visuomotor performance at T1, in intelligence at T2, and no differences at T3 or T4. This study model is useful for investigating the cognitive effects of AED because it allows selection of a uniform sample, eliminating variables such as type, frequency, and gravity of seizures that complicate this kind of study.


Interictal cognitive aspects of epilepsy. Common methodological problems in the assessment of interictal cognitive deficits in epilepsy include limitations in neuropsychological tests selected and subject sampling problems. Neuropsychological functioning is related to a series of seizure history variables with an emphasis on those seizure factors showing the closest relationships. However, even these relationships are limited in scope, and it has been noted that no study has used multivariate procedures to demonstrate maximal relationships with measures of mental abilities. This technique was applied to data on 487 cases, and slightly stronger relationships were produced. However, this still did not account for the vast majority of the variance in cognitive tests. Conclusions concerning neuropsychological functioning in epilepsy require careful attention to sampling problems and other factors, and seizure history variables have only limited relationships with cognitive functioning, even when they are combined in an optimal fashion.


Molecular genetic analysis of the cytochrome P450-debrisoquine hydroxylase locus and association with cancer susceptibility. The cytochrome P450-dependent monooxygenases play a central role in the metabolism of chemical carcinogens. The action of these enzymes can lead to either carcinogen detoxication or activation. Differences in P450 expression in animal models give rise to large differences in susceptibility to chemical carcinogens, so genetic polymorphisms in P450 expression may be expected to be an important factor in individual human susceptibility to cancer. Of particular interest is the genetic polymorphism at the cytochrome P450-debrisoquine/sparteine hydroxylase locus (CYP2D6). Although this is a minor liver P450, its polymorphic expression is associated with the abnormal metabolism of at least 30 therapeutic drugs, including beta-blockers and tricyclic antidepressants. Conflicting reports have been made on the association of this polymorphism with cancer susceptibility. This disagreement may be attributable to limitations of the phenotyping assay used to identify affected individuals (poor metabolizers, PMs). In order to clarify these anomalies, we have developed a simple DNA-based assay with which we can identify the majority of PMs. The assay is centered around the primary gene defect responsible for the polymorphism, a G to A transition at the junction of intron 3/exon 4 which results in a frame-shift in the resultant mRNA. The frequency of this mutation is 70-80% in PMs. We have studied the frequency of mutated alleles in a control population and in a wide range of cancer patients. No association between this polymorphism and lung cancer susceptibility was observed; however, in other populations of cancer patients some very interesting shifts were found in the proportion of PMs and heterozygotes from that in the normal population.


Genetic monitoring of human polymorphic cancer susceptibility genes by polymerase chain reaction: application to glutathione transferase mu. Several genes involved in the metabolism of carcinogens have been found to be polymorphic in human populations and are associated with increased risk of cancer at some sites. This study focuses on the polymorphic enzyme glutathione transferase mu (GT mu). Smokers with low lymphocyte GT mu activity are at an approximately 2-fold higher risk for lung cancer and an approximately 3-fold higher risk for stomach and colon adenocarcinomas. Recent cloning and sequencing of the GST1 gene has allowed the development of convenient genotyping methods based on restriction fragment length polymorphisms (RFLP) or the polymerase chain reaction (PCR). The GST1 polymorphism has been shown to be a deletion of the gene locus. To detect the presence or absence of the gene we amplified exons 4-5 and/or exons 6-7 of the GST1 gene by PCR. PCR amplification produced bands of 215-bp or 273-bp from individuals with one or two copies of the GST1 allele and no band if the individual was homozygously deleted (0/0). In the exon 6-7 PCR, we co-amplified a 268-bp portion of the beta-globin gene as an internal reference standard for quantitative analysis of product yield. This allowed homozygote individuals (+/+) to be distinguished from heterozygotes (+/0). We have compared the GST1 genotype to lymphocyte GT mu activity measured on trans-stilbene oxide (TSO) in the lymphocytes of 45 individuals. Low GT mu activity (< 67 pmole/min/10(7) cells) was strongly associated (24/24) with the GST1 0/0 genotype. With the exception of one individual, activities greater than 67 pmole/min/10(7) were associated with the presence of the GST1 allele (20/21). Individuals with the highest GT-TSO activity were found to be homozygous for GST1. (+/+), while heterozygotes (+/0) generally had lower activity, suggesting a gene dosage effect in lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)


DNA adducts and related biomarkers in populations exposed to environmental carcinogens. Prevention of environmentally related cancer will be enhanced by the availability of sensitive early warning systems and by improvements in quantitative assessment of human risks. Accordingly, we have carried out a series of molecular epidemiologic studies aimed at validating a panel of biologic markers, including carcinogen-DNA and -protein adducts, sister chromatid exchange, micronucleus formation, DNA strand breaks, and DNA repair capacity. Results from three such studies illustrate the usefulness of these biomarkers in elucidating low-dose-response relationships, correlations between biomarkers, and the range of variation in biomarkers between individuals exposed to similar concentrations of carcinogens. Low-level workplace or ambient exposures to styrene, ethylene oxide, and polycyclic aromatic hydrocarbons (PAH) were associated with significant increases in both molecular dose of carcinogens (adducts) and various markers of preclinical effects. Correlations between biomarkers varied by exposure. For example, in the styrene study, sister chromatid exchange frequency was not correlated with any of the markers, in contrast to the studies of ethylene oxide and PAH. Significant molecular effects were observed not only in occupationally exposed people but also in residents of an area in Poland characterized by high levels of air pollution. For example, the mean PAH-DNA level in exposed residents (winter sample) was 30.4 adducts per 10(8) nucleotides. This level was significantly higher than that of adducts seen in summer samples from the same area (4.2/10(8), or in winter samples from residents of a rural area (11.01/10(8). Significant seasonal variation in PAH-DNA adduct formation in this group was consistent with recorded fluctuations in air pollution levels. Striking interindividual variation was observed in all three exposed populations.


Application of biomarkers to risk assessment. Due to difficulties in conducting epidemiological studies, most estimates of cancer risk are based on data from animal bioassays. Extrapolation of cancer risk estimates in animals to humans requires an assumption of equal potency across species based on the average daily dose. The purpose of this paper is to examine the ability to predict tumor incidence across species from DNA adduct concentrations resulting from exposure to carcinogens. A 100-fold range of structurally diverse adduct concentrations corresponding to the same tumor incidence raises questions about quantitative predictability across chemical classes and across species. Differences in adduct structure, mutagenic efficiency, adduct repair rates, and cellular proliferation could account for some of the differences. For specific carcinogen-DNA adducts, the steady-state levels associated with a 50% tumor incidence appear to vary over a narrower range. An equal incidence of liver tumors was obtained at equal concentrations of aflatoxin B1-DNA adducts for rats and trout. A 2- to 3-fold range of 4-aminobiphenyl-DNA adduct concentrations between mice and dogs appears to be associated with nearly equal bladder tumor incidence, on the basis of limited data. In humans, a 5-fold higher concentration of a 4-aminobiphenyl-DNA adduct in bladders of smokers than of nonsmokers is compatible with the relative risk of bladder cancer due to smoking. DNA adduct concentrations certainly can be used to improve quantification of chemical exposures for epidemiological studies. Although promising, more data are needed to judge the usefulness of DNA adduct concentrations to predict cancer incidence across species.


Role of proto-oncogene activation in carcinogenesis. The accumulation of genetic damage in the forms of activated proto-oncogenes and inactivated tumor-suppressor genes is the driving force in the evolution of a normal cell to a malignant cell. For example, both the activation of ras oncogenes and the inactivation of several suppressor genes, including p53, have been observed in the development of human colon and lung tumors. Point mutations in key codons can activate ras proto-oncogenes and inactivate the p53 suppressor gene. Thus, several critical genes for tumorigenesis are potential targets for carcinogens and radiation that can induce point mutations at low doses. The ras proto-oncogenes are targets for many genotoxic carcinogens. Activation of the ras gene is an early event--probably the "initiating" step--in the development of many chemical-induced rodent tumors. ras Oncogenes are observed in more human tumors and at a higher frequency than any other oncogene, and activation of the proto-oncogene may occur at various stages of the carcinogenic process. Numerous proto-oncogenes other than the ras genes have been shown to be activated in human tumors and to a lesser extent in rodent tumors. Mechanisms that induce aberrant expression of proto-oncogenes are gene amplification and chromosomal translocation or gene rearrangement. Amplification of proto-oncogenes and possibly gene overexpression during the absence of gene amplification occur in the development of many human tumors. For a specific tumor type, amplification of any one proto-oncogene may occur at a low frequency, but the frequency of tumors in which at least one proto-oncogene is amplified can be much higher. Proto-oncogene amplification is usually associated with late stages of tumor progression; however, amplified HER2/neu has been observed in early clinical stages of mammary neoplasia. Activation of proto-oncogenes by chromosomal translocation has been detected at a high frequency in several hematopoietic tumors. Non-ras genes have been detected by DNA transfection assays in both human and rodent tumors. For example, ret and trk genes were found to be activated by gene rearrangements in human papillary thyroid carcinomas. Several potentially new types of oncogenes have also been detected by DNA transfection assays. The etiology of the genetic alterations observed in most human tumors is unclear at present. Examples of ras gene activation and those documented for mutations in the p53 gene demonstrate that exogenous conditions can induce oncogenic mutants of normal genes. The genetic alterations observed in most human tumors are probably generated by both spontaneous events and exogenous conditions.


Biomarkers in epidemiology: scientific issues and ethical implications. The current generation of biologic markers have three characteristics that differentiate them from previous ones. These include the ability to detect xenobiotics at concentrations at the cellular and molecular level, to detect earlier biologic changes presumptive of disease or disease risk, and to identify a detailed continuum of events between an exposure and resultant disease. If biomarkers are to enhance cancer epidemiology, they must be valid, reliable, and practical. When these characteristics have not been previously demonstrated, pilot studies should be conducted prior to the primary study. Interdisciplinary communication and collaboration is required so that useful markers are selected and that collection and handling, assay, and interpretation are appropriate. The status of many biomarkers is that they have been developed in the laboratory but lack validation for field use. Validation of a marker for use in a population requires attention to issues of background prevalence, sample size, natural history, persistence, variability, confounding factors, and predictive value. Additionally, practical features such as subject preparation, access to specimens, specimen storage aspects, and costs must be clarified. Ultimately, the use of biologic markers in epidemiologic studies will depend on how well the markers increase ability to reduce misclassification, provide for better interpretation of exposure-disease associations, and increase opportunities for prevention. Validation studies and general research using biomarkers also have clinical, ethical, and legal implications. These range from communicating uncertainty about the meaning of a marker to the kinds of societal response that result when groups or individuals are identified as having an "abnormal" marker frequency.


Biomarkers in occupational cancer epidemiology: considerations in study design. Epidemiologic studies of occupational groups have been central to the identification of human carcinogens. The incorporation of a biochemical component into occupational studies of cancer can expand the possibilities for identifying human carcinogens and for understanding the disease process. Two epidemiologic studies of occupation and cancer which include evaluation of biomarkers are described. The association of acetylator phenotype with bladder cancer risk was studied in benzidine-exposed workers. The association of benzene-related leukopenia with leukemia is being studied in benzene-exposed workers. These investigations illustrate issues in the use of biomarkers in epidemiologic studies of cancer risk. Such studies require the identification and characterization of the population at risk. Disease susceptibility factors are amenable for inclusion in these studies and can be statistically modeled as exposure-effect modifiers. Biomarkers of exposure are mainly of importance in short-term longitudinal and cross-sectional studies of exposure and intermediate outcomes and for validation of other data sources. Several sources of error can affect the results of molecular epidemiologic studies. Aside from minimizing laboratory error, consideration must be given in the design and execution of these studies to potential problems in subject selection and field collection of biologic samples and other relevant data.


Molecular epidemiology in cancer risk assessment and prevention: recent progress and avenues for future research. Molecular epidemiology is increasingly being applied in studies of cancer risks derived from exposure to environmental carcinogens of both endogenous and exogenous origins. Analytical methods have been developed that are capable of detecting and quantifying levels of covalent adducts of several important classes of carcinogens with cellular DNA and blood proteins. Methods of sufficient sensitivity and specificity to detect ambient levels of exposure are in current use. These are being used in studies related to tobacco use (polycyclic aromatic hydrocarbons, aromatic amines, tobacco-specific nitrosamines); dietary exposures (aflatoxins, N-nitrosamines, heterocyclic amines); medicinal exposures (cisplatin, alkylating agents, 8-methoxypsoralen, ultraviolet photoproducts); occupational exposures (aromatic amines, polycyclic aromatic hydrocarbons, oxides of ethylene and styrene, and vinyl chloride); and oxidative damage (8-hydroxyguanine, thymine glycol). Methodologic improvements together with their expanded use in feasibility studies continue to produce results that support the validity of this approach for detecting and quantifying exposure to carcinogens. Genetic markers are also being used to detect early biological responses in efforts to link carcinogen exposure to initiating events in the carcinogenesis process. These include, in addition to traditional cytogenetic markers (e.g., chromosomal aberrations, sister chromatid exchange, micronuclei), other alterations in chromosomal structure such as restriction fragment length polymorphisms, loss of heterozygosity, and translocation markers. Specific genetic changes have recently been identified as critical molecular events in the initiation and development of many cancers. Important among these are activation of oncogenes, especially those of the ras family, and inactivation of tumor-suppressor genes (e.g., p53 and Rb) by point mutations and/or chromosomal deletions and other structural changes. Although some of these changes are known to occur in chemically induced tumors of experimental animals, the possible role of chemical carcinogens in the induction of genetic abnormalities in human cancers has yet to be determined. Continuing investigations employing the methods of molecular epidemiology promise to provide further evidence concerning these relationships. Future investigations employing newly developed molecular biological methods, in particular those based on polymerase chain reaction amplification of DNA, to identify alterations in DNA and chromosomal structure, combined with methods for characterizing exposure to carcinogens and early effects, have great potential for further elucidating the role of genotoxic agents in the etiology of human cancers and also for the development of strategies for their prevention.


Detection of ras gene mutations in human lung cancer: comparison of two screening assays based on the polymerase chain reaction. We studied the prevalence of point mutations in ras oncogenes (K-ras and N-ras) in DNA from white blood cells and tumor tissue from 36 untreated patients with non-small-cell lung cancer, all of whom were smokers or ex-smokers. We observed somatic K-ras mutations in one-third of the lung carcinomas studied but no N-ras mutation. K-ras codon 12 mutations were found more frequently in adenocarcinomas than in the other histopathological subtypes studied. More than 60% (10/16) of the lung adenocarcinomas had a codon 12 mutation, most of which were G to T transversions. No mutations was found in white blood cell DNA. Two polymerase chain reaction screening methods, oligonucleotide hybridization and denaturing gradient gel electrophoresis (DGGE), were used to detect the mutations. The oligonucleotide method appears to be more sensitive than DGGE, but DGGE proved to be a reliable nonradioactive method for rapid screening of point mutations in genes relevant to carcinogenesis.


Aberrant crypt foci and microadenoma as markers for colon cancer. Foci of aberrant crypts similar to those seen in experimental animals exposed to colon carcinogens have been identified and quantified on the mucosal surface of fixed resections of human colon after methylene blue staining. Many of the foci in humans showed dysplasia on histologic examination and were considered to be microadenoma (MA). These lesions may be precursors for adenomatous polyps and colorectal cancer. Rats and mice initiated with azoxymethane, then fed diets containing sucrose or casein heated at 180 degrees C to stimulate normal cooking conditions, had three to five times more large MA after 100 days than controls. Thus, cooked sugar and protein contain promoters of the growth of colonic MA. 5-Hydroxymethylfuraldehyde was identified as a promoter in cooked sugar.


Use of breath hydrogen and methane as markers of colonic fermentation in epidemiologic studies: circadian patterns of excretion. Fermentation in the large bowel has been postulated to play a protective role against colon cancer. Hydrogen and methane are end products of this fermentation process and are absorbed into the bloodstream and excreted via expired air in the breath. Breath levels of hydrogen and, to a lesser extent, methane correlate strongly with colonic fermentation and may serve as useful biomarkers for this process. In a preliminary study to assess the usefulness of these two markers in epidemiologic studies, we followed the hourly excretion of the two gases in expired alveolar air for 48 hr in 20 healthy subjects, using a Quintron gas chromatograph equipped with a solid-state detector specific for reducing gases. All subjects excreted hydrogen, but 71% did not excrete methane. Possible atmospheric contamination of the samples was corrected for on the basis of breath carbon dioxide levels. A clear circadian pattern of excretion was observed for breath hydrogen, with a decrease during the early morning followed by a progressive increase during the rest of the day. Methane excretion was constant throughout the day. This study shows that four samples collected at convenient times (0600, 1300, 1800, and 2200 hr) are optimal to characterize individuals by their breath excretions of hydrogen and methane during a 24-hr period.


Role of lime in the generation of reactive oxygen species from betel-quid ingredients. The role of lime in the formation of reactive oxygen species (ROS), i.e., O2-., H2O2, and OH., from betel-quid components (extracts of areca nut and catechu) was investigated in vitro using a chemiluminescence technique and an assay for oxidative DNA damage involving analysis of 8-hydroxy-2'-deoxyguanosine. Of the various areca-nut extracts, the catechin fraction, at alkaline pH, was shown to be the most active producer of ROS. The free Ca(OH)2 content and pH of lime samples (a component of betel quid and chewing tobacco) were highly correlated with the generation of ROS from areca-nut extract in vitro and with oxidative base damage to DNA in vitro. While Fe2+ had an enhancing effect on ROS formation, Mg2+ had a marked inhibitory effect. The cytogenetic effects of ROS generated in vivo were measured in Syrian golden hamsters in which the cheek pouch had been painted with lime and an areca-nut extract or catechu, singly or in combination. The frequency of micronucleated cells was increased only in animals that had received both the areca-nut extract and lime. The frequency of micronucleated cells in exfoliated oral mucosal cells from Indian chewers of betel quid with tobacco containing lime or of tobacco with lime was significantly higher than in a control (no habit) group. These studies demonstrate that addition of lime to betel quid constituents generates ROS, which induce cytogenetic damage in hamster cheek pouch and may contribute to the cytogenetic damage observed in the oral cavity of betel-quid chewers. These results implicate ROS in clastogenesis and probably in the etiology of oral cancer.


Cross-sectional study with multiple measurements of biological markers for assessing stomach cancer risks at the population level. A cross-sectional study to determine correlations between measurable biologic markers and mortality from stomach cancer was performed in various areas of Japan. Blood and urine were collected from randomly selected 40- to 49-year-old men and their spouses in four areas with different rates of mortality from stomach cancer. The samples were analyzed for levels of the micronutrients vitamins A, C, and E, beta-carotene, and lycopene in plasma and for levels of NaCl, nitrate, and N-nitrosamino acids (N-nitrosoproline, N-nitrosothioproline [NTPRO] and N-nitrosomethylthioproline [NMTPRO]) in 24-hr urine. A significant, strong correlation was found between the amount of salt excreted in urine and stomach cancer mortality in both men and women. Although the amounts of nitrate and of the three N-nitrosamino acids in 24-hr urine were not correlated with stomach cancer rates, the low excretion levels of NTPRO and NMTPRO in the lowest risk area for stomach cancer were noteworthy, regardless of the high level of nitrate excretion in the same area. This suggests a lesser degree of endogenous nitrosation in the body. No protective effect of micronutrients was observed in this correlation study; there was, however, a negative correlation between plasma lycopene level and stomach cancer mortality. Salt intake was thus confirmed to play an important role in the development of stomach cancer and is likely to be a rate-regulating factor in Japanese populations. N-Nitrosamino acids and lycopene may also be related to stomach cancer mortality.


Determination of point mutational spectra of benzo[a]pyrene-diol epoxide in human cells. The primary goal of our research consists of developing means sufficiently sensitive to allow assessment of human exposure to environmental carcinogens. We describe here a new approach for analyzing point mutational spectra and a test for its validity and precision using cultured human cells exposed to high doses of environmental carcinogens. The approach in its present form includes a) treatment of independent large cultures of human cells with a carcinogen, b) selection of mutant cells en masse by 6-thioguanine resistance, c) amplification of sequences of interest directly from 6TGR cells using high-fidelity polymerase chain reaction, and d) separation of mutant sequences from nonmutant sequences using denaturing gradient gel electrophoresis. We report use of this protocol to observe induced mutational spectra in exon 3 of the hprt gene in cultured human cells by benzo[a]pyrene-diol epoxide (BPDE), an active form of the widely distributed environmental carcinogen benzo[a]pyrene. BPDE induced predominantly G to T transversions within this target sequence. The variation of the frequency of the mutations among independent cultures is consistent with the interpretation that each of them corresponds to a hotspot.


Nongenotoxic carcinogens: an extension of the perspective provided by Perera. Perera recently discussed the very real problems that accompany any attempt to classify rodent carcinogens into two groups--genotoxic or nongenotoxic. Not the least of these problems is that no agreed definition of these two terms exist. Nonetheless, the current carcinogen databases, for example, that of the U.S. National Toxicology Program (NTP), clearly comprise two broad groups of carcinogens--DNA reactive, mutagenic and multiply carcinogenic chemicals, and others. The others appear to be nonreactive to DNA, are inactive in the primary mutagenicity assays, and usually elicit highly selective carcinogenic responses in animals. These two classes of carcinogen are illustrated by examples taken from the NTP database and are discussed within the possible context of the latter group not being active in humans or, if they are, only when a threshold dose has been exceeded, chronically.


Development of source testing, analytical, and mutagenicity bioassay procedures for evaluating emissions from municipal and hospital waste combustors. Incineration is currently being used for disposal of about 10% of the solid waste generated in the United States, and this percentage will likely increase as land disposal declines. Siting new incinerators, however, is often controversial because of concerns related to the possibility of adverse health effects and environmental contamination from long-term exposure to stack emissions. Specific concerns relate to the adequacies of a) stack emission testing protocols, b) existing regulations, and c) compliance monitoring and enforcement of regulations. U.S. Environmental Protection Agency laboratories are cooperatively conducting research aimed at developing new testing equipment and procedures that will allow a more comprehensive assessment of the complex mixture of organics that is present in stack emissions. These efforts are directed specifically toward developing source testing equipment and procedures, analytical procedures, and bioassay procedures. The objectives of this study were to field test two types of high-volume source dilution samplers, collect stack samples for use in developing analytical and mutagenicity bioassay procedures, and determine mutagenicity of organics associated with emission particles from two municipal waste combustors and a hospital waste combustor. Data are presented for particle concentrations and emission rates, extractable organic concentrations and emission rates, and Salmonella (Ames) mutagenic potency and emission rates. The mutagenic emission rates and emission factors are compared to other incinerators and combustion sources.


EPA priorities for biologic markers research in environmental health. Recent advances in molecular and cellular biology allow for measurement of biologic events or substances that may provide markers of exposure, effect, or susceptibility in humans. The application of these new and emerging techniques to environmental health offers the possibility of significantly reducing the uncertainties that traditionally hamper risk assessments. The U.S. Environmental Protection Agency (EPA) health research program emphasizes the validation of appropriate biologic markers and their application to high-priority Agency issues. The rationale for EPA's biomarker research program is presented, and future research directions are discussed. Exposure biomarkers will receive most of the research emphasis in the near term, particularly body burden indicators of exposure to high-priority chemicals, such as benzene, ozone, selected heavy metals, and organophosphate pesticides. Research on effects biomarkers will attempt to validate the relationship between the observed biological effects and adverse health consequences in humans, especially for cancer, pulmonary toxicity, immunotoxicity, and reproductive/developmental toxicity.


The findings of the Agency for Toxic Substances and Disease Registry Medical Waste Tracking Act report. The Agency for Toxic Substances and Disease Registry (ATSDR) report "The Public Health Implications of Medical Waste: A Report to Congress" has been finalized and submitted to Congress. The report is a comprehensive review of all available data and information on the subject. Based on the data developed in the report, ATSDR concludes that the general public is not likely to be adversely affected by medical waste generated in the traditional health setting. However, the increase of in-home health care and other sources of nonregulated medical waste (e.g., intravenous drug users) provides opportunities for the general public to contact medical waste. In addition, ATSDR concludes that public health concerns exist for selected occupations involved with medical waste. These populations include janitorial and laundry workers, nurses, emergency medical personnel, and refuse workers. The ATSDR report also defines what material should be managed as medical waste and identifies research needs related to medical waste.


Determinants of serum zinc in a random population sample of four Belgian towns with different degrees of environmental exposure to cadmium. This report investigated the distribution of serum zinc and the factors determining serum zinc concentration in a large random population sample. The 1977 participants (959 men and 1018 women), 20-80 years old, constituted a stratified random sample of the population of four Belgian districts, representing two areas with low and two with high environmental exposure to cadmium. For each exposure level, a rural and an urban area were selected. The serum concentration of zinc, frequently used as an index for zinc status in human subjects, was higher in men (13.1 mumole/L, range 6.5-23.0 mumole/L) than in women (12.6 mumole/L, range 6.3-23.2 mumole/L). In men, 20% of the variance of serum zinc was explained by age (linear and squared term, R = 0.29), diurnal variation (r = 0.29), and total cholesterol (r = 0.16). After adjustment for these covariates, a negative relationship was observed between serum zinc and both blood (r = -0.10) and urinary cadmium (r = -0.14). In women, 11% of the variance could be explained by age (linear and squared term, R = 0.15), diurnal variation in serum zinc (r = 0.27), creatinine clearance (r = -0.11), log gamma-glutamyltranspeptidase (r = 0.08), cholesterol (r = 0.07), contraceptive pill intake (r = -0.07), and log serum ferritin (r = 0.06). Before and after adjustment for significant covariates, serum zinc was, on average, lowest in the two districts where the body burden of cadmium, as assessed by urinary cadmium excretion, was highest. These results were not altered when subjects exposed to heavy metals at work were excluded from analysis.


Toxicity of vesicant agents scheduled for destruction by the Chemical Stockpile Disposal Program. The vesicant agents of the unitary chemical munitions stockpile include various formulations of sulfur mustard [bis-(2-chloroethyl) sulfide; agents H, HD, and HT] and small quantities of the organic arsenical Lewisite [dichloro(2-chlorovinyl) arsine; agent L]. These agents can be dispersed in liquid, aerosol, or vapor form and are capable of producing severe chemical burns upon direct contact with tissue. Moist tissues such as the eyes, respiratory tract, and axillary areas are particularly affected. Available data summarizing acute dose response in humans and laboratory animals are summarized. Vesicant agents are also capable of generating delayed effects such as chronic bronchitis, carcinogenesis, or keratitis/keratopathy of the eye under appropriate conditions of exposure and dose. These effects may not become manifest until years following exposure. Risk analysis derived from carcinogenesis data indicates that sulfur mustard possesses a carcinogenic potency similar to that of benzo[a]pyrene. Because mustard agents are alkylating compounds, they destroy individual cells by reaction with cellular proteins, enzymes, RNA, and DNA. Once begun, tissue reaction is irreversible. Mustard agents are mutagenic; data for cellular and laboratory animal assays are presented. Reproductive effects have not been demonstrated in the offspring of laboratory rats. Acute Lewisite exposure has been implicated in cases of Bowen's disease, an intraepidermal squamous cell carcinoma. Lewisite is not known to generate reproductive or teratogenic effects.


The third United States-Japan meeting on the Toxicological Characterization of Environmental Chemicals. This report summarizes the discussion of the Third U.S.-Japan Meeting on the Toxicological Characterization of Environmental Chemicals held under the auspices of the U.S.-Japan cooperative in research and development in science and technology. Recent data on the interrelationships between toxicity, cell proliferation, and carcinogenicity are presented.


Perinatal and multigenerational effect of carcinogens: possible contribution to determination of cancer susceptibility. Perinatal exposure to carcinogens may contribute to the determination of susceptibility to cancer in two situations: a) exposure in utero of embryonal or fetal somatic cells to carcinogens, and b) prezygotic exposure of the germ cells of one or both parents to carcinogens. Epidemiological as well as experimental studies demonstrate that exposure to carcinogens in utero increases the occurrence of cancer postnatally. Studies with experimental animals suggest that prezygotic exposure of germ cells to carcinogens can result in an increased incidence of cancer not only in immediate but also in subsequent generations. Although several studies suggest a transgeneration effect of carcinogens in human populations, the evidence cannot yet be considered conclusive. In particular, while some hypotheses can be advanced, the mechanism(s) by which increased susceptibility or predisposition to cancer may be transmitted via the germ cells has not yet been clarified. In conjunction with exposure both in utero and prezygotically, it is important to consider postnatal exposure to possible tumor-promoting agents. Results from experimental animals suggest that oncogenes can be activated transplacentally, and human studies indicate that tumor-suppressor gene inactivation may be involved in the transgenerational effect of carcinogens.


Intragenomic repair heterogeneity of DNA damage. The mutagenic and carcinogenic consequences of unrepaired DNA damage depend upon its precise location with respect to the relevant genomic sites. Therefore, it is important to learn the fine structure of DNA damage, in particular, proto-oncogenes, tumor-suppressor genes, and other DNA sequences implicated in tumorigenesis. Both the introduction and the repair of many types of DNA lesions are heterogeneous with respect to chromatin structure and/or gene activity. For example, cyclobutane pyrimidine dimers are removed more efficiently from the transcribed than the nontranscribed strand of the dhfr gene in Chinese hamster ovary cells. In contrast, preferential strand repair of alkali-labile sites is not found at this locus. In mouse 3T3 cells, dimers are more efficiently removed from an expressed proto-oncogene than from a silent one. Persistent damage in nontranscribed domains may account for genomic instability in those regions, particularly during cell proliferation as lesions are encountered by replication forks. The preferential repair of certain lesions in the transcribed strands of active genes results in a bias toward mutagenesis owing to persistent lesions in the nontranscribed strands. Risk assessment in environmental genetic toxicology requires assays that determine effective levels of DNA damage of producing malignancy. The existence of nonrandom repair in the mammalian genome casts doubt on the reliability of overall indicators of carcinogen-DNA binding and lesion repair for such determinations. Tissue-specific and cell-specific differences in the coordinate regulation of gene expression and DNA repair may account for corresponding differences in the carcinogenic response to particular environmental agents.


Cisplatin-DNA damage and repair in peripheral blood leukocytes in vivo and in vitro. We have extended our studies on the relationship between cisplatin/carboplatin-induced DNA damage in readily accessible tissue(s) and clinical response to therapy. Such an approach may assist in the study of cancer drug resistance and in establishing parameters for assessing human populations for sensitivity to DNA damaging agents in the environment. Platinum-DNA adduct levels were measured by atomic absorbance spectrometry. DNA repair capacity was assessed in human T-lymphocytes by the ability to repair cisplatin lesions in cellular DNA or in transfected plasmid DNA. In a "blinded" study of 21 patients receiving combination cisplatin/carboplatin drug therapy, there was a direct relationship between DNA damage in leukocytes and disease response (summary two-sided p = 0.00011). The cohort of patients had 15 different tumor types, suggesting that blood tissue and tumor tissue of an individual may process platinum-DNA damage similarly regardless of the tissue of origin of the tumor. In leukocytes in vivo, persistence and accumulation were prominent features of the cisplatin-DNA adduct profile. Functional DNA repair capacity has been studied in eight human leukocyte cell lines in vitro (three, T-cells; three, B-cells; one, monocytic; one, promyelocytic), using a host cell reactivation assay with cisplatin-damaged pRSVcat. In the three T cell lines studied, host cell reactivation efficiency was directly related to the cells' abilities to repair cisplatin-damaged cellular DNA (correlation coefficient = 0.993).(ABSTRACT TRUNCATED AT 250 WORDS)


Multiple genetic alterations in human carcinogenesis. Cancer development in man appeared to be a multistage process as suggested by epidemiological studies on commonly occurring gastric, colon, and breast cancers and also on human retrovirus-related leukemia, and by the finding by physicians and surgeons of precancerous lesions for many types of neoplasias. In the last 10 years it has become evident that human cancers have multiple genetic alterations caused by point mutations, recombinations, amplifications, and/or deletions. The genes affected include both oncogenes and tumor-suppressor genes and genes that accelerate cell proliferation and metastasis. Cancers with more malignant properties and poorer prognosis are generally associated with larger numbers of genetic alterations. These multiple genetic alterations are considered to be a direct reflection of the multiple steps involved in carcinogenesis. The multiple genetic alterations are caused by multiple environmental carcinogenic substances or factors, each of which usually exists only at minute concentrations and does not exert any major impact alone except under particular occupational, iatrogenic, and locally geographic conditions. The fact that carcinogenesis is a multistep process involving multiple genetic alterations clearly needs to be taken into consideration in assessing the risks of environmental carcinogenic substances or factors. The increasing incidence of multiple primary cancers is also most easily understood from the viewpoint of multiple steps in carcinogenesis. Possible multiple approaches to cancer prevention should therefore be considered in relation to multistep carcinogenesis and multiple carcinogenic factors.


Relationship of H-ras-1, L-myc, and p53 polymorphisms with lung cancer risk and prognosis. Proto-oncogenes (H-ras-1 and L-myc) and tumor-suppressor gene (p53) loci have been implicated in lung carcinogenesis. DNA restriction fragment length polymorphisms at these gene loci are being evaluated in a case-control study as markers predictive of risk for cancer or of prognosis when cancer is present. The cases and controls had a cigarette-smoking history of 40 or more pack years or other abnormalities in pulmonary function tests, their ages were closely matched (64 years for cases and 61 years for controls) and the ratio of Caucasians to African Americans was close to unity (cases, 0.95:1.00, controls, 1.00:0.88). The H-ras-1 gene contains an insertion deletion polymorphism. Inheritance of rare H-ras-1 alleles, defined by MspI digestion, confers a relative risk for lung cancer of 2.0 (95% confidence interval, 0.5-7.3) for Caucasians and 3.2 (0.9-11.6) for African Americans (74 cases, 67 controls). The L-myc gene sequence has a restriction site (EcoR1) polymorphism between the second and third exons. Inheritance of restriction site-present alleles was reported to confer poor prognosis (presence of lymph node metastases) in Japanese lung cancer patients. This hypothesis was tested in both case-control study subjects (56 cases, 55 controls) and additional surgical cases (40), but no evidence was found to support the hypothesis in the U.S. population. The p53 gene is a tumor-suppressor gene that can encode either a proline or an arginine in the 72nd residue. No associations was found between the minor allele (proline) and diagnosis of lung cancer (76 cases, 68 controls).(ABSTRACT TRUNCATED AT 250 WORDS)


Polymorphisms for aromatic amine metabolism in humans: relevance for human carcinogenesis. The metabolic pathways associated with carcinogenic aromatic amines in humans provide an excellent example of polymorphisms that appear to be relevant to human carcinogenesis. In this regard, the N-acetylation of arylamines and the O-acetylation of their N-hydroxy metabolites are catalyzed preferentially by a genetically polymorphic acetyltransferase, high activity of which has been correlated with decreased risk for urinary bladder cancer and increased susceptibility to colorectal cancer. Cytochrome P450IA2, the principal liver enzyme involved in aromatic amine N-oxidation, exhibits a wide interindividual variation that appears trimodal in several populations and is clearly inducible by cigarette smoking and probably other host factors as well. UDP-Glucuronosyltransferases, which catalyze the N-glucuronidation of N-hydroxyarylamines and are likely to be responsible for their transport to the colon, show widely varied but unimodal distributions in humans. In contrast, human liver sulfotransferase activity for N-hydroxyarylamines, which would be expected to decrease their transport through the circulation, is catalyzed by a polymorphic enzyme(s) that is expressed at higher levels in blacks, as compared to whites, and could contribute to their relatively lower incidence of urinary bladder cancer. Peroxidative activation of aromatic amines can also occur, especially from prostaglandin H synthase in the urinary bladder and myeloperoxidase in the lungs of cigarette smokers, and both show considerable individual variability, apparently due to the extent of tissue inflammation.(ABSTRACT TRUNCATED AT 250 WORDS)


Elucidation of catalytic specificities of human cytochrome P450 and glutathione S-transferase enzymes and relevance to molecular epidemiology. A number of different approaches have been used to determine the catalytic selectivity of individual human enzymes toward procarcinogens. Studies with cytochrome P450 (P450) enzymes and glutathione S-transferases are summarized here, and recent work with pyrrolizidine alkaloids, aflatoxins, 4,4'-methylenebis(2-chloroaniline), and ethyl carbamate is discussed. In some cases a single enzyme can catalyze both activation and detoxication reactions of a chemical. The purification and characterization of human lung P4501A1 and the development of a noninvasive assay for human P4502E1 are also described.


Human cytochromes P450: evolution and cDNA-directed expression. As the first step in the process of carcinogenesis, most chemical carcinogens require metabolic activation by cytochromes P450 for conversion to highly reactive electrophiles that bind covalently to DNA. Studies in rodents suggest that low or high levels of expression of a single P450 can determine susceptibility or resistance to chemically induced cancer. Although rodent systems have been used to explore the molecular basis of chemical carcinogenesis and to identify chemicals capable of damaging genes and causing cancer, it has been understood that marked species differences exist in the expression, regulation, and catalytic activities of different P450s. Thus, large efforts are underway to study the catalytic activities of human P450s directly by expression of their cDNAs in cultured cells. Two systems are being used: a) transient high-level P450 production in HepG2 cells for analysis of catalytic activities, and b) stable expression in human B-lymphoblastoid cells to study promutagen and procarcinogen activation. These studies define the relative contributions of individual P450 forms to the activation of various chemical carcinogens. The B-lymphoblastoid cDNA expression system can also be used to determine whether a chemical will be hazardous or toxic to humans. The most intriguing aspects of P450s are the occurrence of human genetic polymorphisms in P450 expression, which could be a risk factor for chemical carcinogenesis. The best-studied P450 genetic polymorphism is the debrisoquine/sparteine polymorphism which is due to mutant CYP2D6 alleles. Four mutant alleles have been characterized that account for most of the defective CYP2D6 genes in Caucasians. These can be detected by polymerase chain reaction assays.(ABSTRACT TRUNCATED AT 250 WORDS)


The human glutathione S-transferase supergene family, its polymorphism, and its effects on susceptibility to lung cancer. Cytosolic glutathione S-transferases (GSTs) are a supergene family of dimeric enzymes capable of detoxifying a number of carcinogenic electrophiles. Of the numerous components of tobacco smoke, the polycyclic aromatic hydrocarbons appear to be the principal compounds that yield substrates for these enzymes, GSTM1-1 being effective with those PAH derivatives so far studied; however, the gene locus for GSTM1 is polymorphic, containing two well-characterized expressing genes and a null allele. Use of cDNA for GSTM1-1 or appropriate fragments of genomic clones as probes in Southern blots indicated that the null allele is due to the absence of GSTM1. In preliminary experiments, described here, with lung tissue from smokers, levels of 32P-postlabeled nuclease P1-enhanced DNA adducts were inversely correlated with levels of antigen cross-reacting with antibody to GSTM1-1, suggesting that initiation depends on the expression of GSTM1-1. Since similar quantities of DNA adducts and GSTM1-1 activity have been shown to occur in bronchial and peripheral lung, however, the development of malignancy, which is usually in the bronchial region, presumably depends on additional factors that bring about promotion and progression, which are not necessarily affected by GSTM1 expression. Two epidemiological studies have been carried out in which a possible correlation between the absence of GSTM1 and lung cancer incidence is considered. In the first, involving a U.S. population sample, smokers with and without lung cancer were phenotyped, and a highly significant correlation between the absence of GSTM1-1 activity and adenocarcinoma of the lung was observed.(ABSTRACT TRUNCATED AT 250 WORDS)


Interindividual variation in carcinogen metabolism and bladder cancer risk. Epidemiological studies indicate that subjects of the genetically based slow acetylator phenotype may be at higher risk for bladder cancer than fast acetylators, particularly when they are exposed to carcinogenic arylamines: N-acetylation is a detoxification step in the metabolism of some arylamines. We describe two collaborative studies on tobacco smoking, in which markers of internal dose (arylamine-hemoglobin adducts) and markers of genetically-based metabolic polymorphism have been coupled. In the first investigation, we found that hemoglobin adducts formed by mononuclear arylamines have high reciprocal correlation coefficients, as do adducts from binuclear arylamines. This tendency of adducts with structurally similar arylamines to correlate reciprocally explains a large proportion of the residual variance seen after controlling for smoking habits (number and type of cigarettes). In the second study, the concentration of 4-amino-biphenyl-hemoglobin adducts varied according to three independent determinants: number of cigarettes, type of tobacco (air or flue cured), and acetylator phenotype (slow and fast). The dose-response relationship between the amount of tobacco smoked and level of 4-aminobiphenyl-hemoglobin adducts in the slow acetylators (with an immediate steep increase of the adducts) was different from that in the fast acetylators (with a more regular increase). These findings from "molecular epidemiology" may contribute to an understanding of the role of metabolic polymorphism in human carcinogenesis.


The somatotropic axis in puberty.

The somatotropic axis in puberty. Sex steroids markedly affect GH pulsatility by altering GH pulse amplitude without affecting GH pulse frequency. The type of sex steroid (testosterone or estrogen) appears to determine the timing of the pubertal growth spurt although both steroids appear to influence the amount of GH released from the pituitary. GH levels also affect gonadal secretion of sex steroids. The effects of the two are synergistic, but there is a real therapeutic dilemma of what to increase and when in children who are deficient in either GH or gonadotrophin secretion. Augmented GH pulsatility, particularly during the day, may alter markedly the interpretation of standard endocrine tests. Finally, the insulin resistance arising from an increased circulating concentration of GH may have important implications for the management of insulin-dependent diabetes during puberty.


Clinical pathophysiology of the somatotropic (GH) axis in adults. In summary, GH secretion and, to a lesser extent, GH metabolic clearance, are subject to regulation in health and disease. Nutritional, body compositional, metabolic, and age-related and sex-steroid related mechanisms as well as adrenal glucocorticoids, thyroid hormones, and renal and hepatic function all govern pulsatile GH release in adults. Moreover, tissue resistance to GH action may occur as an inborn (Laron dwarf) or acquired (fasting, diabetes mellitus, chronic renal failure) defect and modulate the function of the somatotropic axis. Finally, GH action is controlled by the local synthesis of IGFs and their binding proteins in target tissues.


Long-term endurance training alters the hypothalamic-pituitary axes for gonadotropins and growth hormone. In a prospective fashion we have studied the impact of chronic exercise of two intensities on the hypothalamic-pituitary-end organ axes for gonadotropins and GH in gynecologically mature, previously sedentary women. Physiologic alterations are evident in both axes with a doubling of 24-hour mean serum GH concentrations at 1 year and smaller, transient changes in pulsatile LH release during the first four menstrual cycles. The latter period of physiologic adaptation should be studied more intensively with more frequent exercise evaluation. Perhaps more significant "adaptation to stress" would be quantitated. We also emphasize that gynecologically less mature women were not studied and only the early follicular phase was evaluated. Adaptive changes of greater magnitude (including amenorrhea) might have been produced if a different group of women, a markedly different training regimen, or a different phase of the menstrual cycle were studied. Finally, whether or not they participate in physical training, younger amenorrheic women are at increased risk for diminished lumbar spine bone mineral content and skeletal fractures.


Regulation and dysregulation of the hypothalamic-pituitary-adrenal axis. The corticotropin-releasing hormone perspective. This article is an up-to-date review of the impact that the discovery of corticotropin-releasing hormone (CRH) has had on basic science and clinical medicine. It discusses hypothalamic CRH, placental CRH, immune CRH, and hypothalamic and immune CRH. Clinical studies in normal and disease states and synthesis and future directions also are presented.


Syndrome of inappropriate antidiuresis.

Syndrome of inappropriate antidiuresis. Since it was first recognized 35 years ago, the syndrome of inappropriate antidiuretic hormone (SIADH) secretion has become the most commonly recognized cause of hyponatremia among hospitalized patients. The syndrome is caused by excessive intake of fluids when urinary dilution is impaired by physiologically inappropriate secretion or administration of vasopressin or other antidiuretic hormones. Inappropriate secretion of the hormone may be ectopic by a malignancy or ectopic and can ensure from any of three different types of osmoregulatory defects. Rarely, there is no demonstrable defect in the osmoregulation of vasopressin. The excessive fluid intake may be due to inappropriate thirst but often is iatrogenic. The syndrome occurs in association with many diseases, particularly of the lungs and brain, and can also be caused by drugs or surgery. Its principal symptoms are neurologic and due to the associated hypo-osmolality of body fluids. Diagnosis requires exclusion of certain other hormonal or hemodynamic disorders that can also increase vasopressin or impair urinary dilution. Therapy differs depending on the severity and duration of the hyponatremia but is always based on cautiously raising plasma sodium by fluid restriction, infusion of hypertonic saline, or administration of drugs that block the antidiuretic effect of vasopressin.


Pathologic hyperprolactinemia.

Pathologic hyperprolactinemia. Unlike other pituitary hormones, PRL is under tonic inhibition by the hypothalamus by way of the PRL inhibitory factor, dopamine. GAP and GABA may also be inhibitory. PRL-releasing factors include TRH and VIP and possibly others. Circulating PRL is predominantly monomeric, although some patients with hyperprolactinemia appear to have increased quantities of the less biologically active polymeric forms. PRL is secreted episodically, with an increase in the amplitude of the secretory pulses with sleep. A transitory increase also occurs in response to the protein component of meals. Basal PRL levels increase in response to the hormonal milieu of pregnancy, and suckling postpartum triggers PRL release. Pathologic increases of PRL owing to hypothalamic dysregulation occur with a variety of medications, including the neuroleptics, metoclopramide, antidepressants, methyldopa, reserpine and verapamil, abuse of opiates and cocaine, renal insufficiency, cirrhosis, hypothyroidism, adrenal insufficiency, neurogenic stimulation, and idiopathically. Hyperprolactinemia also may occur from structural lesions of the stalk and hypothalamus, which cause disinhibition with or without maintenance of PRF activity, ectopic neoplasm production, and, most commonly, from prolactinomas. Diagnostic testing consists of routine chemistry and thyroid testing and imaging with MRI or CT. Dopamine agonists are the treatment of choice of prolactinomas of all sizes. Transsphenoidal surgery is an alternative for the patient who does not respond to medical therapy or who wishes definitive tumor removal, realizing that long-term cure is achieved in only 50% to 60% of patients with microadenomas and a much lower number in those with macroadenomas. Radiotherapy is reserved for patients who do respond to either medical or surgical treatment. Patients wishing to become pregnant usually are treated with bromocriptine, although prepregnancy surgical debulking may be advisable for those with large macroadenomas to reduce problems with tumor enlargement.


Central hypothyroidism.

Central hypothyroidism. Central hypothyroidism is an uncommon condition characterized by insufficient thyroid gland stimulation by TSH, owing to hypothalamic and/or pituitary dysfunction. It is rarely isolated but more often occurs in conjunction with deficiencies of other pituitary hormones, as well as with neurologic symptoms and signs owing to hypothalamic/pituitary lesions. The diagnosis rests on documentation of clinical and biochemical hypothyroidism with an inappropriately low or nonelevated serum TSH level. Recent studies suggest that the temporal pattern of TSH secretion, as well as TSH structure, is altered in central hypothyroidism, providing a mechanism for the induction of the hypothyroid state in this condition.


Neuroendocrinology of aging in the male and female. Many changes in the neuroendocrine axis occur with healthy normal aging in humans. Women cease ovarian follicle maturation and menstrual cycles entering the estrogen-deficient state termed menopause. Although not without risk, estrogen and progesterone replacement in postmenopausal women has been shown to ameliorate the complications of lowered estradiol concentrations, such as hot flushes and osteoporsis, while improving the risk of cardiovascular complications. Aging men have lowered serum free and total testosterone concentrations and may experience a less well defined symptom complex termed andropause. Both signs and symptoms of thyroid disease and interpretation of thyroid function tests are difficult in aging humans. Specifically, TSH secretion is diminished in aging so that suppressed serum TSH concentrations are indicative of but not specific for hyperthyroidism. Cortisol secretion is not altered in aging, although serum concentrations of DHEA-S are lower. Prolactin concentrations are increased in both men and women, with the increase being more pronounced in men. The clinical significance of this increase has not yet been determined. Finally, elderly humans are more likely to develop difficulties with fluid and electrolyte balance. Although some alterations in AVP secretion have been shown in the elderly, plasma concentrations are similar in young and elderly subjects. Other mechanisms, such as decreased glomerular filtration rate and a decreased sensitivity of the thirst mechanism in response to hypertonicity, may be important contributors to fluid and electrolyte imbalances.


Two-year survey of the incidence of Lyme borreliosis and tick-borne encephalitis in a high-risk population in Sweden. A survey was made over a two-year period (September 1987 to August 1989) of a population living in an area endemic for Lyme borreliosis and tick-borne encephalitis in Sweden. For each patient a blood sample was collected and a questionnaire completed annually. All sera were tested for an antibody response to Borrelia burgdorferi in an EIA using sonicated antigen and for an antibody response to the tick-borne encephalitis virus using an EIA and a haemagglutination inhibition test. Antibodies to Borrelia burgdorferi and tick-borne encephalitis virus were detected in 89 (25.7%) and 40 (11.6%) respectively of 346 samples collected in August 1987. In the first year of the study 14 of 303 subjects (4.6%) developed Lyme borreliosis and in the second year 9 of 277 subjects (3.2%). A significant increase in the antibody titre for Borrelia burgdorferi was seen in 14 of 303 (4.6%) subjects in the first year and 8 of 277 (2.9%) subjects in the second year. An earlier episode of Lyme borreliosis or an elevated antibody titre did not seem to protect against reinfection. One case of tick-borne encephalitis was seen each year. Seroconversion for tick-borne encephalitis virus was found in 3 of 258 (1.2%) subjects in the first year and 5 of 211 (2.4%) in the second year, excluding subjects who had undergone successful immunisation or had earlier been hospitalised for tick-borne encephalitis. The study thus demonstrated a high yearly incidence of tick-borne infections in a population at risk.


Chlamydial infections of the heart.

Chlamydial infections of the heart. Chlamydiae are common human pathogens, causing a broad spectrum of infectious diseases. Chlamydial infections involving the heart have been described in numerous previous reports. These organisms are documented to cause endocarditis, myocarditis and pericarditis. Furthermore, Chlamydia pneumoniae, the recently discovered respiratory pathogen, has also been implicated in coronary artery disease. For the first time the literature on involvement of the heart in chlamydial infections is reviewed. Information on the discovery of Chlamydia species is also included and the problem of the species determination of Chlamydia in interpretation of the older literature is mentioned.


A case of disseminated Mycobacterium marinum infection in an immunocompetent patient. An unusual case of Mycobacterium marinum cutaneous infection is described. As a result of marked delay in the diagnosis, extensive local inflammation and destructive osteomyelitis occurred together with cutaneous dissemination in an immunocompetent host. Pathologic fractures in the infected bone necessitated amputation of the involved digit. The most striking feature of this case was the development of multiple widespread cutaneous lesions for several months following amputation of the infected digit and initiation of appropriate antimicrobial therapy. These new cutaneous lesions may reflect local immune and inflammatory reactions to previously disseminated microorganisms.


Evaluation of the Septi-Chek AFB system in the recovery of mycobacteria. The performance of the Septi-Chek AFB System (Roche) in the isolation of mycobacteria was compared to that of culture on Lowenstein-Jensen (LJ) medium and the Bactec radiometric system. The Septi-Chek AFB system detected a significantly higher number of positive specimens (62/66 versus 47/66 for Bactec and 39/56 for LJ medium) and was more often the only medium in which an isolate was recovered. The average time for detection of isolates was very similar for the Septi-Chek AFB and Bactec systems which were both significantly faster than LJ medium in the majority of isolates.


Variability of surface-exposed antigens of different strains of Moraxella catarrhalis. For serological diagnosis of infection with Moraxella (Branhamella) catarrhalis it is important to determine if there is variability of antigenic properties among different strains. Cross-reactions of nine strains were investigated by an immunofluorescence test using sera from immunized rabbits. All titres but one were 1:256 or higher, the highest being 1:4096. Thus a high degree of antigenic similarity was demonstrated among different strains of Moraxella catarrhalis. However, the homologous titres of six sera were 2 to 16 times higher than the titres for other strains indicating strain variations in antigenic properties of some surface components. There was no correlation between lipopolysaccharide type and titre in the immunofluorescence test.


Killing kinetics of five orally administered antibiotics at clinically achievable concentrations against Moraxella catarrhalis. Time-kill kinetic studies were used to measure the bactericidal activity of amoxicillin/clavulanic acid (in a new form for pediatric use), cefaclor, cefuroxime, cefixime and erythromycin against 30 beta-lactamase producing Moraxella catarrhalis strains. Antibiotics were tested at the mean maximum serum concentration observed after administration of a standard dose and at 0.5 x Cmax, 0.33 x Cmax and 0.25 x Cmax. A 2 log10 reduction in colony counts was obtained with the Cmax of amoxicillin/clavulanic acid and cefixime after 5 h of incubation. After 24 h of incubation a decrease of 3 and 4 log was observed with cefixime and amoxicillin/clavulanic acid respectively. At 0.5 x Cmax and 0.33 x Cmax, bactericidal activity was obtained only with amoxicillin/clavulanic acid.


Error rates in cefoperazone and cefoperazone-sulbactam disk tests with Enterobacteriaceae and Pseudomonas aeruginosa. In a collaborative study involving five medical centers, 6% of 2,440 consecutive isolates of Enterobacteriaceae were resistant to cefoperazone; resistance to cefoperazone was reduced to < 1% by the addition of sulbactam. Susceptibility to cefoperazone and cefoperazone-sulbactam was accurately predicted by disk diffusion tests. Resistance to cefoperazone, however, was not as reliably detected by disk tests and results of dilution tests were not always consistent. The prevalence of resistance to cefoperazone and/or the ability to detect resistance had a significant influence on very major error rates for individual laboratories.


A simple medium for the primary isolation of Haemophilus ducreyi. Two simple, inexpensive media containing gonococcal agar-base, supplemented with 5% Fildes' extract and either chocolated or unchocolated horse blood (GC-FHBC or GC-FHB) were compared with the standard gonococcal agar-based (GC-HgS) and Mueller-Hinton agar-based media (MH-HB) normally used for primary isolation of Haemophilus ducreyi from presumptive chancroid lesions. Overall, Haemophilus ducreyi was recovered from 162 of 178 (91%) samples from primary chancroid lesions. As a single isolation medium GC-HgS proved the most sensitive with an isolation rate of 80% followed by GC-FHB (75%), MH-HB and GC-FHC (both 71%). Use of a combination of GC-HgS and MH-HB resulted in isolation of Haemophilus ducreyi in 160 of 178 cases (90%). Since GC-FHB is approximately one-quarter the cost of the combination and half the cost of GC-HgS or MH-HB alone, this medium could prove suitable for diagnostic purposes in developing countries where chancroid is endemic.


Impaired detection of faecal verocytotoxin in the presence of Clostridium difficile cytotoxin in patients with haemolytic uraemic syndrome. Three cases of haemolytic uraemic syndrome associated with infection with verocytotoxin producing Escherichia coli are described. The concomitant presence of Clostridium difficile cytotoxin in the patients' stool impaired the detection of free faecal verocytotoxin. Stool specimens containing Clostridium difficile cytotoxin should thus be considered negative for verocytotoxin only after neutralisation of the Clostridium difficile cytotoxin with antitoxin.


Use of western blot to analyze the reactivity of sera from patients with Mediterranean spotted fever. The reactivity of antigenic components of Rickettsia conorii with sequentially obtained sera from 20 adult Spanish patients with Mediterranean spotted fever was analyzed by Western blot. The major rickettsial antigens reacting with the serum samples corresponded to molecular weights of 135 and 115 kDa. These antigens constantly exhibited higher staining intensity than the other antigens, and reacted with 100% and 86.7%, respectively, of acute sera and with 100% of convalescent phase samples. Rickettsial lipopolysaccharide antigens reacted with 94.7% of sera collected in the fourth and fifth week after onset of symptoms. Other major antigens reactive in the blots had molecular sizes of 160, 100, 90 and 60 kDa, and a relatively frequent humoral immune response was also seen to antigens of 80, 73 and 55 kDa.


Comparative activity of the topical quinolone OPC-7251 against bacteria associated with acne vulgaris. The antibacterial activity of the topical quinolone OPC-7251 against bacteria commonly found in acne vulgaris was tested in vitro by an agar dilution method. The MIC50 was 0.25 mg/l for Propionibacterium acnes, 0.125 mg/l for Propionibacterium granulosum, 0.03 mg/l for Staphylococcus aureus and 0.06 mg/l for coagulase-negative staphylococci. Compared with seven other antibiotics tested (ciprofloxacin, penicillin, erythromycin, tetracycline, clindamycin, fusidic acid and gentamicin), OPC-7251 had potent activity against both propionibacteria and staphylococci and the lowest incidence of resistant strains.


Comparative in vitro activity of Ro 40-6890, Ro 41-3399, and other antimicrobial agents against anaerobic bacteria. The in vitro activity of the ester Ro 41-3399 and its free active acid Ro 40-6890 was tested against 189 strains of anaerobic bacteria in comparison to other oral cephalosporins and to antimicrobial agents established in the treatment of anaerobic infections. Prevotella, Porphyromonas, Peptostreptococcus, Fusobacterium and Clostridium spp. were susceptible to Ro 40-6890, with few exceptions. Due to its lack of activity against the major pathogens of the Bacteriodes fragilis group, Ro 40-6890 does not promise to be of major use in the treatment of infections caused by anaerobes.


Clinical pharmacology of loop diuretics in health and disease. There are differences in metabolism and excretion of the loop diuretics which extrapolate to differences in pharmacokinetic behaviour in different disease states. For example, furosemide is eliminated in equal portions by renal and non-renal routes; the non-renal route involves primarily glucuronidation. Both renal and non-renal pathways are impaired during renal insufficiency, such that the elimination half-life is prolonged considerably in this disease state. In contrast, there seems to be little change in disposition in patients with liver disease. Bumetanide and torasemide have non-renal elimination pathways via the hepatic cytochrome system. In patients with renal insufficiency these non-renal pathways of elimination are left intact so that there is little prolongation of half-life in such patients. In contrast, in patients with liver disease or with congestive hepatopathy, there is impairment in non-renal elimination so that relatively more drug appears in the urine. With all loop diuretics, response is governed by the amount of drug appearing in the urine. By assessing the relationship between urinary excretion rates of the diuretic and sodium excretion rate, a maximal response which amounts to a fractional excretion of sodium of approximately 20% can be defined. Thus it is possible to define a maximal dose as the amount of drug necessary to attain a fractional excretion of sodium of 20%. Studies in different disease states using escalating doses can thereby use this relationship to define a dose above which little is to be gained in terms of therapeutic efficacy.(ABSTRACT TRUNCATED AT 250 WORDS)


Effects of diuretics on renal excretory function. From a clinicopharmacological standpoint, the urinary excretory potency of diuretics should be assessed comparatively, on the basis of placebo-controlled changes in 24 h natriuresis, following single oral doses administered to healthy adult subjects who are in steady-state habitual external sodium balance. The potency of 30 diuretic formulations has been evaluated. Two formulations of loop diuretics (muzolimine 20 mg and torasemide 2.5 mg) are non-diuretic. The majority of the other formulations of loop diuretics studied (e.g. furosemide 40 mg and torasemide 5 and 10 mg) are comparatively less potent than most of the common formulations of early distal tubular diuretics studied (e.g. hydrochlorothiazide 25 and 50 mg, xipamide 10, 20 and 40 mg). Hydrochlorothiazide 25 mg and furosemide 80 mg have similar potencies. The presence of a rebound in natriuresis between 6 and 24 h after administration of loop diuretics make the majority of the common formulations of these drugs less potent than most common formulations of thiazide-type diuretics.


Comparative mechanisms of action of diuretic drugs in hypertension. This review concerns the modes of action of thiazides, loop- and potassium-sparing diuretics, with particular emphasis on their antihypertensive activity. Thiazide diuretics inhibit an enzyme in the basolateral cell membrane in the distal tubule, thus bringing about an impaired absorption and enhanced excretion of both Na+ and Cl- ions. The loss of Na+ ions is countered by the exchange from Na+ against K+, hence causing a loss of K+ ions. The renal excretion of Ca++ ions is impaired, that of Mg++ ions enhanced. Loop diuretics inhibit a carrier mechanism that enhances the inward transport into the tubular cells of Na+, K+ and Cl- ions as well as water. This process, which occurs in the thick ascending limb of Henle's loop, enhances the urinary excretions of these ions together with water and Ca++ and Mg++ ions. Potassium-sparing diuretics comprise two different categories. Triamterene and amiloride inhibit a local transport mechanism in the distal tubular cells which allows the influx of Na+ and its exchange against K+ or H+ ions. Concomitantly, the excretion of Na+, but not that of K+, ions is enhanced. Aldosterone antagonists inhibit the renal effects of aldosterone at the receptor level and impair the reabsorption of Na+ ions and water and their exchange against K+ ions. Despite detailed knowledge of the renal mode of action of the diuretics, the mechanism whereby they exert their antihypertensive activity is still uncertain. The initial reduction in plasma volume is accompanied by reduction in cardiac output and increased systemic vascular resistance. Continued treatment leads to a return to normal in cardiac output and a reduction in systemic vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)


Modulation of electrolyte excretion by potassium retaining diuretics. Triamterene and amiloride belong to the potassium retaining diuretics of the cycloamidine type. These agents exert natriuretic as well as antikaliuretic effects. After administration of high doses an additional magnesium-sparing property also becomes evident. Whereas amiloride is only metabolized to a minor extent, triamterene is rapidly bio-transformed to the phase-I metabolite, hydroxytriamterene, and the phase-II metabolite, hydroxytriamterene sulphuric acid ester. This acidic phase-II metabolite is still diuretically active, but its electrolyte excretion profile is different from the parent compound: although the natriuretic properties are not altered, the potassium retention is very weak. Further studies in rats with cycloamidine derivatives of the triamterene type containing neutral, acidic or basic side chains at the phenyl moiety as well as with basic pteridine derivatives, revealed further evidence that the natriuretic, antikaliuretic and antimagnesiuretic effects can be influenced almost independently by structural variations of the parent drug. Thus, it was possible to obtain compounds predominantly increasing sodium excretion without affecting potassium or magnesium excretion. On the other hand, substances could be developed with mainly antikaliuretic effects, or compounds, which enhanced sodium and reduced magnesium excretion and did not interfere with the potassium elimination. Based on these findings, it can be concluded that distal tubular transport of sodium, potassium and magnesium may be influenced independently from each other. These renal effects of triamterene and its derivatives seem to be independent of their antiarrhythmic actions, as suggested by recent studies.


Potency of vascular risk factors as the basis for antihypertensive therapy. Hypertension is a powerful predisposing risk factor for cardiovascular disease at all ages and in both sexes. Epidemiological assessment indicates the largest risk ratios for stroke and congestive heart failure (CHF), but coronary heart disease (CHD) is the most common and most lethal sequela of hypertension. Examination of the risk of cardiovascular sequelae in the hypertensive population indicates that this is not uniform and varies over a 10-fold range, depending on the associated risk factors. Systolic pressure merits greater consideration than the diastole pressure because isolated systolic hypertension is a powerful cardiovascular risk at all ages. Furthermore, recent trials have indicated the benefit of therapy for systolic-based hypertension in the elderly, even using a diuretic, for coronary disease as well as stroke. Persons with hypertension have a high prevalence of associated cardiovascular risk factors, including elevated cholesterol, reduced HDL-C, diabetes, left ventricular hypertrophy (LVH), and obesity. About 9% under the age of 65 years have an associated overt cardiovascular disease; above age 65 about 30% are so afflicted. Each of these risk factors can double the risk associated with hypertension. Because they are so common, a large fraction of the disease sequelae of hypertension is attributable to these associated risk factors. The high risk of coronary disease in hypertensive patients is concentrated in those with a high total/HDL-cholesterol ratio, impaired glucose tolerance, high fibrinogen, ECG abnormalities, and cigarette smokers. Stroke risk in hypertensive persons is concentrated in those with cardiovascular disease, diabetes, atrial fibrillation, LVH and cigarette smoking.(ABSTRACT TRUNCATED AT 250 WORDS)


Ambulatory blood pressure monitoring and antihypertensive treatment. This paper outlines the advantages of ambulatory blood pressure monitoring (ABPM) in the evaluation of the efficacy of antihypertensive drugs. The main advantage is that ABPM allows the antihypertensive effect of a drug or drug regimen to be determined in daily life conditions and to uncover whether the treatment employed is associated with untoward hypotensive episodes. Furthermore, ABPM facilitates the design of studies on antihypertensive drug efficacy because the 24 h mean blood pressure is devoid of a placebo effect and its reproducibility is much greater than office blood pressure. This has permitted demonstration of the efficacy of several antihypertensive drug regimens, including diuretic studies, based on relatively small numbers of subjects. A further advantage of ABPM is that it allows drug treatment efficacy to be evaluated in relation to blood pressure variability, another possible determinant of the organ damage related to hypertension.


Diuretics and arteriolar resistance and arterial compliance in human hypertension. Differences exist between short- and long-term haemodynamic effects of diuretics. In the short term, plasma volume depletion is accompanied by increased peripheral vascular resistance and decreased cardiac output. In the long term cardiac output returns toward normal, peripheral resistance falls to below pretreatment values and blood volume remains lower than before therapy. This long-term decrease in volume may contribute to the chronic antihypertensive effects of diuretics. Many studies have reported that arterial compliance is increased after antihypertensive drug administration. However, it is important to known whether such action is a primary pharmacological effect or mediated by the reduction in blood pressure. Two different methods using pulse wave velocity measurements have been applied to determine the pressure-dependence of compliance before and after thiazide administration. In the first method, blood pressure was controlled as a variable by changing transmural pressure of the forearm encased in a rigid plastic tube. In the other method arterial compliance in the brachial artery was evaluated using a simple non-linear arterial model. Both methods demonstrated that the decrease in blood pressure with thiazide therapy was associated with increased arterial compliance. However, by measuring arterial compliance at the same pressure, its isobaric values were found to be unchanged. The implication is that the increase in compliance of the peripheral artery observed with diuretics is due to the decline in blood pressure rather than to a change in the intrinsic properties of the arterial wall.


Mechanisms of diuretic effects on carbohydrate tolerance, insulin sensitivity and lipid levels. Diuretics have long been recognized to increase the concentration of some atherogenic plasma lipids and to reduce insulin sensitivity and adversely influence carbohydrate tolerance, but the mechanisms responsible have not been conclusively established. Early studies reporting diabetes in diuretic-treated patients implicated potassium loss as responsible. More recent observations have extended this suggestion by also demonstrating a role for the renin-angiotensin-aldosterone system. In addition, direct effects of antihypertensive agents on insulin sensitivity have been demonstrated; both hormonal and haemodynamic factors have been implicated. Diuretic-induced lipid changes have also been consistently observed, but the mechanisms for these findings are much less clear. A link between the carbohydrate and insulin alterations and those of lipids has been suggested. Plasma catecholamine concentration may also be increased by diuretics and it is possible that this may also influence lipid metabolism. While the mechanisms of these metabolic effects of diuretics are not yet clearly established, useful clues based on dose relationships and susceptible populations can be discerned. Observations from combination drug therapies also provide additional information regarding potential mechanisms. The availability of new drug therapies associated with few metabolic changes further suggest that effective diuretic therapy need not always be associated with significant adverse metabolic changes.


Effect of diuretic therapy on hypertensive left ventricular hypertrophy. Left ventricular hypertrophy (LVH) has been identified as a major independent risk factor for cardiovascular morbidity in patients with essential hypertension. It is also established that antihypertensive drug therapy is associated with regression of LVH in many patients. However, it is unclear whether all antihypertensive agents are equally effective in regressing LVH and whether this process is drug-specific or primarily related to blood pressure control. There is no universal agreement on the influence of diuretics on LVH in hypertension. Several major trials have shown consistent reversal of electrocardiographic manifestations of LVH during diuretic-based therapy. The results of studies employing echocardiographic measurements have been more variable; however, most echocardiographic studies have been flawed by lack of controls or blinding, short duration of follow-up, small sample size, inclusion of patients without LVH, and lack of consideration of previous or concomitant therapy. This review provides a critical examination of the available data on both sides of the question.


Effect of diuretics on the plasma lipid profile. Hypertension, dyslipidaemia, glucose intolerance (associated with insulin resistance and compensatory hyperinsulinaemia) and other abnormalities are complementary coronary risk factors which often occur in association. A familial trait for essential hypertension seems to coexist commonly with defects in carbohydrate and lipoprotein metabolism which can be detected before the appearance of hypertension. Diabetes mellitus as well as obesity promotes the development of hypertension and dyslipidaemia. Moreover, certain drugs used for antihypertensive therapy can further modify lipoprotein and glucose metabolism. Thiazides in high dosage and loop-diuretics can increase serum low-density-lipoprotein cholesterol (LDL-C) and/or very-LDL-C and the total C/high-density lipoprotein cholesterol (HDL-C) ratio, while HDL-C is largely unchanged; triglycerides (Tg) are also often elevated. Premenopausal women may be protected from this side effect. Whether diuretic-induced dyslipidaemia is dose-dependent and low thiazide doses (i.e. hydrochlorothiazide < or = 12.5 mg daily) are less active, awaits clarification. The diuretic-antihypertensive agent, indapamide, given at a dose of 2.5 mg.day-1, seems to exert no relevant effect on serum lipoprotein or glucose metabolism. The potassium-sparing diuretic, spironolactone, also may be largely neutral with regard to lipids. Moreover, potassium sparing diuretics may possibly counteract, at least in part, a dyslipidaemic influence of potassium-loosing diuretics in medium dose. Drug-induced dyslipidaemia, as well as glucose intolerance, represent potentially adverse influences. In the hypertensive population, effective blood pressure control with traditional drug therapy based on thiazide-type diuretics in high dosage led to a distinct decrease in cerebrovascular morbidity and mortality, but a lesser decrease in coronary events.(ABSTRACT TRUNCATED AT 250 WORDS)


Diabetes, impaired glucose tolerance and insulin resistance with diuretics. There is a definite relation of diuretic treatment to impaired glucose tolerance and biochemical diabetes, and a probable relation to insulin resistance. The effect of diuretics on glucose tolerance is dose-related. Spironolactone does not impair glucose tolerance even at high dosage, but apparent differences between other diuretics may well be due to comparison at doses which are not equivalent. Diuretic-induced changes in carbohydrate metabolism are not conclusively related to altered potassium homeostasis, and impaired glucose tolerance occurs when relatively low doses of thiazide are combined with potassium-sparing agents. The effect of diuretics on glucose tolerance is largely and possibly wholly reversible. These disturbances of carbohydrate homeostasis have been detected by detailed biochemical testing, and their clinical importance is uncertain. In established diabetes, diuretics have a rapid and substantial adverse effect on metabolic control. In non-diabetic subjects diuretics may rarely cause or trigger a serious hyperosmolar non-ketotic diabetic syndrome. This apart, it is not known whether the metabolic changes cause clinical diabetes or lead to microvascular complications in the long-term. It is now established that biochemical diabetes, glucose intolerance and insulin resistance probably do not increase the risk of coronary heart disease in treated hypertensive patients. Diuretics should be avoided in patients with diabetes, otherwise they remain an excellent choice for first-line antihypertensive therapy.


Diuretics and cardiovascular risk factors. Thiazide diuretics are efficacious, either as monotherapy or in combination with other antihypertensive drugs. They reduce blood pressure in a high percentage of hypertensive patients with minimal subjective side effects. There is increasing evidence that the use of diuretics, singly or in combination, will reduce morbidity and mortality associated with essential hypertension in both young and elderly subjects. Although diuretics may induce some changes in the plasma lipid profile, serum uric acid concentration and glucose metabolism, there is little evidence that these changes are of clinical significance. The increase in serum cholesterol concentration has rarely persisted in any trial beyond the first year of treatment. The incidence of diabetes mellitus in diuretic treated subjects is only about 1%, even when large doses are used. Gout may be precipitated in susceptible subjects, but is uncommon. For these reasons, diuretics should remain a preferred first-step drug of choice in the management of hypertension.