9392504
Chromatographic estimation of iothalamate and p-aminohippuric acid to measure glomerular filtration rate and effective renal plasma flow in humans.
Iothalamate (IOT) clearance and p-aminohippuric acid (PAH) clearance are used for estimation of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). A simple and rapid method is described for simultaneous determination of IOT and PAH in the same chromatogram in the serum and urine of humans. The mobile phase consisted of methanol-50 mM sodium monobasic phosphate with 0.5 mM tetrabutyl ammonium hydrogen sulfate (18:82, v/v), pumped at a rate of 0.8 ml/min on a C18 reversed-phase column. Samples of serum and urine were deproteinized with two volumes of acetonitrile containing the internal standard, p-aminobenzoic acid (PABA). The UV detector was set at 254 nm and peak height ratios of PAH or IOT to PABA were calculated with an integrator. Precision and accuracy were within 15% for both PAH and IOT. The recovery of PAH in urine and serum were 94% and 91%, respectively. For IOT the corresponding recoveries were 93% and 92%, respectively. This method clearly distinguishes acetyl-PAH from PAH and has been validated in healthy volunteers.
36005104
Volume Overload in Dialysis: The Elephant in the Room, No One Can See
interests of the authors. However, considering the totality of the evidence, I am less convinced that this marker is superior to other volume markers. First, there are few head-to-head studies comparing BIA to other established markers of volume. Second, there is no range that defines ‘normal’. Unlike blood pressure (BP) or cholesterol, there is no target that has been established. The normal values are obtained from healthy subjects whose body composition differs substantially from those on dialysis. Extrapolating from healthy subjects to those with ESRD on hemodialysis does not appear scientifically valid. Third, there is no study to my knowledge that demonstrates convincingly that compared to probing dry weight without BIA, BIA-guided dry weight reduction results in improved outcomes. Most data provided to support the use of BIA are associative and observational. A large amount of observational data does not prove causation. We therefore have to be cautious in interpreting these data as ‘strongly indicative of fluid overload’. Nearly all markers of volemia suffer from the same shortcomings. These shortcomings include lack of normative data, and data being largely observational and associative in nature. As an example, several observational studies suggest that B-type natriuretic peptide (BNP), NT-proBNP or other natriuretic peptides are associated with volume state among people with ESRD on dialysis [2–10] . However, only one study has been reported to date that relates the change in BNP to an intervention of probing dry weight [11] . In this study, a direct relationship existed at baseline between BNP and interdialytic ambulatory BP. Since interdialytic ambulatory BP is reVolume overload is the invisible threat to the health of dialysis patients. Currently, Medicare incentivizes the measurement of the dose of dialysis (urea reduction ratio) but has no measure of volume. Perhaps this is because the few who can recognize the epidemic nature of volume excess cannot agree on how to define it. Whereas, some have proposed interdialytic weight gain (IDWG) as a marker of volume, the in-depth review of Hecking et al. [1] quite clearly and importantly makes the distinction that IDWG should not be confused with hypervolemia. One has to wonder how IDWG got confused with dry weight in the first place. It appears that epidemiologists decided to use IDWG as a proxy of dry weight because of its ready availability in large databases. IDWG is a marker that is convenient; it can be measured easily and it can be related to outcomes such as all-cause mortality. This analysis was performed and a relationship emerged between IDWG and all-cause mortality. But establishing a relationship between IDWG and mortality does not establish causality. It could be numerous other factors, measured and unmeasured, associated with IDWG which may be causally related to mortality. Factors such as missing or cutting short dialysis, not taking medications as prescribed, and consuming a diet rich in phosphorus and potassium are some confounding factors that may also be associated with IDWG but may be more plausibly related to mortality. The authors discuss several markers of volume excess. Although several exist, one marker, bioimpedance analysis (BIA), is discussed in great detail. This is understandable given both the academic and intellectual property Published online: July 6, 2013 Nephrology American Journal of
24249726
Regulation of circadian blood pressure: from mice to astronauts.
PURPOSE OF REVIEW
Circadian variation is commonly seen in healthy people; aberration in these biological rhythms is an early sign of disease. Impaired circadian variation of blood pressure (BP) has been shown to be associated with greater target organ damage and with an elevated risk of cardiovascular events independent of the BP load. The purpose of this review is to examine the physiology of circadian BP variation and propose a tripartite model that explains the regulation of circadian BP.


RECENT FINDINGS
The time-keeper in mammals resides centrally in the suprachiasmatic nucleus. Apart from this central clock, molecular clocks exist in most peripheral tissues including vascular tissue and the kidney. These molecular clocks regulate sodium balance, sympathetic function and vascular tone. A physiological model is proposed that integrates our understanding of molecular clocks in mice with the circadian BP variation among humans. The master regulator in this proposed model is the sleep-activity cycle. The equivalents of peripheral clocks are endothelial and adrenergic functions. Thus, in the proposed model, the variation in circadian BP is dependent upon three major factors: physical activity, autonomic function, and sodium sensitivity.


SUMMARY
The integrated consideration of physical activity, autonomic function, and sodium sensitivity appears to explain the physiology of circadian BP variation and the pathophysiology of disrupted BP rhythms in various conditions and disease states. Our understanding of molecular clocks in mice may help to explain the provenance of blunted circadian BP variation even among astronauts.
191311
Assessment of iothalamate plasma clearance: duration of study affects quality of GFR.
BACKGROUND AND OBJECTIVES
Measurement of GFR is important for the management of chronic kidney disease (CKD). Although bolus administration of radiocontrast agents is commonly used to measure GFR, the optimal duration of sampling to assess their plasma clearance is unknown. The purpose of this study was to evaluate whether the duration of plasma sampling influences precision and estimation of GFR.


DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS
GFR was measured by sampling plasma 12 times over 5 h in 56 patients with CKD (mean age 64 yr, 98% men, 79% Caucasian, 34% diabetics, estimated GFR 31.8 +/- 14.2 ml/min/1.73 m(2)). In a subset of 12 patients we measured GFR by sampling plasma 17 times over 10 h.


RESULTS
Short sampling intervals considerably overestimated GFR measured using total plasma iothalamate clearance, especially in larger patients. In the higher estimated GFR group (>30 ml/min/1.73 m(2)), the 5-h GFR was 17% higher and 2-h GFR 54% higher compared with the 10-h GFR, which averaged 40.3 ml/min/1.73 m(2). In the lower estimated GFR group (<30 ml/min/1.73 m(2)), the 5-h GFR was 36% higher and 2-h GFR 126% higher compared with the 10-h GFR, which averaged 22.2 ml/min/1.73 m(2). Short sampling duration also reduced the precision of the estimated GFR from 1.67% for 10-h GFR, to 3.48% for 5-h GFR, and to 7.07% for 2-h GFR.


CONCLUSIONS
GFR measured over a longer duration with multiple plasma samples spanning the distribution and elimination phases may improve precision and provide a better measure of renal function.
11453581
Proinflammatory effects of oxidative stress in chronic kidney disease: role of additional angiotensin II blockade.
Oxidative stress plays an important role in causing progressive chronic kidney disease (CKD). We examined the influence of add-on ANG II receptor blockade administered as losartan (50 mg/day for 1 mo) on oxidative stress and proinflammatory state of the kidney in patients with CKD. All subjects were taking an angiotensin-converting enzyme inhibitor plus other antihypertensive agents. Oxidative stress to lipids and proteins was measured by an HPLC assay for malondialdehyde (MDA) and carbonyl concentration, respectively. Urinary inflammation was measured by monocyte chemotactic protein-1 (MCP-1) excretion rate. The etiology of CKD was type 2 diabetes mellitus in 12 and glomerulonephritis in 4 patients. There was no change in proteinuria or 24-h ambulatory blood pressure (BP) with add-on ANG II receptor blockade with losartan therapy. Before losartan therapy, urinary protein and albumin oxidation were 99 and 71% higher, respectively, compared with in plasma (P < 0.05). There was a 35% reduction in urinary oxidized albumin with add-on losartan therapy (P = 0.036). Urinary and plasma MDA were elevated compared with age-matched controls. Urinary MDA was significantly reduced from 4.75 +/- 3.23 to 3.39 +/- 2.17 micromol/g creatinine with add-on losartan therapy. However, plasma MDA or oxidized proteins did not change in response to additional ANG II blockade. A good correlation was seen between the change in urinary oxidized albumin and MCP-1 levels (r = 0.61, P = 0.012). These data demonstrate that oxidative damage to urinary protein and lipids can be reduced with additional ANG II receptor blockade, independently of reductions in proteinuria or BP. Urinary measurements of markers of oxidative damage to lipids and proteins appear to be more sensitive than plasma measurements in patients with CKD. The significant association of the change in urinary MCP-1 with a reduction in oxidative stress supports the role of the redox state in the kidney with renal fibrosis and progressive kidney damage.
22176722
Alar web in cleft lip nose deformity: study in adult unilateral clefts.
BACKGROUND
The correction of alar webbing in unilateral cleft lip nose deformity is challenging because of progressive distortions in the alar web region during the period of growth. Alar webbing is a persistent universal deformity in both the primary and secondary cleft lip noses. The purpose of this article is to study the alar web deformity in adult patients with unilateral cleft lip noses.


METHODS
Twenty-five patients aged 13 years and older presenting with unilateral cleft nasal deformity were included. Preoperative and postoperative measurements of the nose, along with detailed intraoperative recording of the deformed anatomy, were done. Preoperative magnetic resonance imaging was also done in selected cases. Transcolumellar open rhinoplasty was performed in all the cases, and nasal septal straightening with centralization was done. Cleft alar base augmentation was done using bone graft to restore symmetry of the nasal tripod. Both the cleft and noncleft alar cartilages were extensively mobilized from the skin and mucosal sides. The overgrown and caudally slumped cleft-side alar cartilage was resected caudally and was then resuspended in a symmetrical position with the noncleft alar cartilage. A midline-strut septal cartilage extension graft was used to restore the tip aesthetics. The skin overlying the alar web was in-rolled after semilunar cartilage resection, and skin excision was also done to restore symmetry with the opposite vestibule. The remaining secondary cleft nasal and lip deformities were corrected depending upon the specific presenting pathologic abnormality.


RESULTS
The cleft alar cartilage was found to be caudally displaced in all the cases. The caudal border of the lateral crus was prolapsing in the cavity of the vestibule on the superomedial aspect and was tenting the skin in the area of the weak triangle, producing the characteristic alar web deformity. In the study group, the maximum width of the cleft alar cartilage at the level of the lateral crus was increased by approximately 4 mm when compared with the noncleft alar cartilage. The before- and after-rhinoplasty surgery results were objectively assessed using a patient, surgeon, and independent observer survey. The cosmetic result of the nasal tip complex was found to be very good and good (90%), satisfactory (5%), and poor (5%) in patients.


CONCLUSIONS
The alar web in unilateral cleft lip nose deformity is the result of caudal overgrowth and migration of the alar cartilage. The caudal edge of the prolapsed lateral crus overhangs the cleft-side nasal aperture on its superomedial aspect, producing this deformity. Satisfactory correction of this deformity should envisage caudal resection and repositioning of the dislocated alar cartilage along with caudal resection of the lateral crus with in-rolling of the skin after resection to achieve symmetric results in unilateral cleft lip rhinoplasty.
771397
Structural analysis of botulinum neurotoxin type E catalytic domain and its mutant Glu212-->Gln reveals the pivotal role of the Glu212 carboxylate in the catalytic pathway.
The seven serotypes of botulinum neurotoxins (A-G) produced by Clostridium botulinum share significant sequence homology and structural similarity. The functions of their individual domains and the modes of action are also similar. However, the substrate specificity and the peptide bond cleavage selectivity of their catalytic domains are different. The reason for this unique specificity of botulinum neurotoxins is still baffling. If an inhibitor leading to a therapeutic drug common to all serotypes is to be developed, it is essential to understand the differences in their three-dimensional structures that empower them with this unique characteristic. Accordingly, high-resolution structures of all serotypes are required, and toward achieving this goal the crystal structure of the catalytic domain of C. botulinum neurotoxin type E has been determined to 2.1 A resolution. The crystal structure of the inactive mutant Glu212-->Gln of this protein has also been determined. While the overall conformation is unaltered in the active site, the position of the nucleophilic water changes in the mutant, thereby causing it to lose its ability to activate the catalytic reaction. The structure explains the importance of the nucleophilic water and the charge on Glu212. The structural differences responsible for the loss of activity of the mutant provide a common model for the catalytic pathway of Clostridium neurotoxins since Glu212 is conserved and has a similar role in all serotypes. This or a more nonconservative mutant (e.g., Glu212-->Ala) could provide a novel, genetically modified protein vaccine for botulinum.
20955522
Ovarian cancer: strategies for overcoming resistance to chemotherapy
Ovarian cancer is responsible for 4% of deaths from cancer in women. Treatment comprises a combination of surgery and chemotherapy, but patients typically experience disease relapse within 2 years of the initial treatment. Further treatment can extend survival, although relapse eventually occurs again. A better understanding of the mechanisms that underlie this drug resistance should allow treatment to be optimized, so that substantial improvements in the outlook for women with this disease can be achieved.
24638854
Structure determination of an FMN reductase from Pseudomonas aeruginosa PA01 using sulfur anomalous signal.
The availability of high-intensity synchrotron facilities, technological advances in data-collection techniques and improved data-reduction and crystallographic software have ushered in a new era in high-throughput macromolecular crystallography. Here, the de novo automated crystal structure determination at 1.28 A resolution of an NAD(P)H-dependent FMN reductase flavoprotein from Pseudomonas aeruginosa PA01-derived protein Q9I4D4 using the anomalous signal from an unusually small number of S atoms is reported. Although this protein lacks the flavodoxin key fingerprint motif [(T/S)XTGXT], it has been confirmed to bind flavin mononucleotide and the binding site was identified via X-ray crystallography. This protein contains a novel flavin mononucleotide-binding site GSLRSGSYN, which has not been previously reported. Detailed statistics pertaining to sulfur phasing and other factors contributing to structure determination are discussed. Structural comparisons of the apoenzyme and the protein complexed with flavin mononucleotide show conformational changes on cofactor binding. NADPH-dependent activity has been confirmed with biochemical assays.
23959361
Polyaromatic hydrocarbon profile of a mineral oil (JBO-P) by gas chromatography.
The present investigation was aimed at identifying the compound(s) responsible for the carcinogenic activity of a variety of jute batching oil (known as non-FDA variety, pre-FDA variety, or JBO-P), a crude petroleum distillate substantially used in jute industries. This was initially performed by isolating from JBO-P a polyaromatic hydrocarbon (PAH) fraction containing compounds of more than three rings. This fraction was then analysed for its PAH profile by gas chromatography and individual components identified by comparing its flame ionisation detector (FID) signal with those obtained from reference PAHs. The results revealed that PAHs of more than three rings, reported to be a recognised class of chemical carcinogens, were present in the JBO-P sample at the level of 3300 mg/kg of oil (0.33%, w/w); benzo(a)pyrene and dibenz(a,h)anthracene, known to be highly potent carcinogens, constituted 129 mg/kg (0.0129%, w/w) and 29 mg/kg (0.0029%, w/w) of the total oil, respectively; and except for a few signals, the PAH profile of JBO-P was found to be somewhat similar to that reported for a sample of carcinogenic used engine oil.
39931674
Is the patient brain-dead?
A 45 year old male working as a labourer in the agricultural sector was brought to the emergency room with complaints of difficulty in opening the eye-lids, dysphagia, dysphonia, dyspnea, and progressive weakness in all four limbs, after awakening from sleep. At presentation, patient had no spontaneous respiratory efforts and was deeply cyanosed. Endotracheal intubation was performed immediately and the patient was mechanically ventilated. Physical examination revealed an afebrile patient with a heart rate of 130 beats/minute and blood pressure of 160/100 mm Hg. He was comatose with absent motor responses to painful stimuli, complete ptosis, external, and internal ophthalmoplegia. Deep tendon reflexes and plantars were absent. Fang marks typical of snakebite were noted in the right middle finger. Patient was started on anti-snake venom (Haffkine Institute, Mumbai) at a dose of 100 mL stat followed by 50 mL at 6 hours, deep venous thrombosis and stress ulcer prophylaxis along with supportive care. Arterial blood gas analysis, serum electrolytes, liver, and renal function tests done were within normal limits. After initiation of …