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Biomedical subjects

V Shah

Publications and source records attributed to V Shah.

At least 145 records · Page 8Linked to original sources
PubMed1990

Phytase from Klebsiella Sp. No. PG-2: purification and properties.

A phytase (EC 3.1.3.8) was extracted from rat intestinal bacterium, Klebsiella Sp. No. PG.-2, and purified 50-fold by ammonium sulphate fractionation, ion-exchange chromatography and gel filtration. The enzyme is inducible in nature. The pH optimum was at 6.0 for all the inositol phosphates studied and this characterized the enzyme as an acid phosphohydrolase. Of a range of potential substrates tested, only p-nitrophenyl phosphate alongwith the inositol phosphates was hydrolyzed. It exhibits a Km of 2.0 mM; temperature optimum of 37 degrees C and energy of activation 9,120 cal/mole for all the inositol phosphates studied. The activity was inhibited by Ag2+, Hg2+, Cu2+, fluoride and high substrate concentration.

6-Phytase↗
PubMed1989

A laminin-like adhesive protein concentrated in the synaptic cleft of the neuromuscular junction.

A striking example of topographic specificity in synapse formation is the preferential reinnervation of original synaptic sites on denervated muscle fibres by regenerating motor axons. This specificity is mediated by the basal lamina of the synaptic cleft. A glycoprotein, s-laminin, has now been identified that is selectively associated with synaptic basal lamina and is recognized by motoneurons. Molecular cloning reveals that s-laminin is a novel homologue of laminin, a potent promoter of neurite outgrowth.

Base Sequence↗
PubMed1989

Variability of urine albumin excretion in normal and diabetic children.

The variability of urine albumin excretion (UAE) was studied in normal and diabetic children and, in addition, the best method of expressing the data was investigated. In 39 timed overnight urine samples from diabetic children, the urine albumin creatinine clearance ratio (CA/CC) was compared with the urine albumin creatinine concentration ratio (UA/UC), the urine albumin excretion rate (UAER) and the urine albumin concentration (UA). UA/UC predicted CA/CC (r = 0.95) better than either UAER (r = 0.83, P less than 0.02) or UA (r = 0.90), 0.1 greater than P greater than 0.05). The within-individual and the between-individual variability in overnight UA/UC in 171 urine samples from 73 normal children was compared with that of 406 urine samples from 119 diabetic children, using a "random effects type 2 nested analysis of variance" model. Geometric mean (range) UA/UC (mg/mmol) in diabetic children, 0.55 (0.04-6.90), was greater than in normal children, 0.33 (0.05-2.10, P less than 0.01), and 18% of diabetics had a value of UA/UC above the normal range. Within-individual variance was the same in normals (0.12) and diabetics (0.12), but between-individual variance in diabetics (0.18) was much greater than in normals (0.03). These data show that within-individual observations for both normals and diabetics are highly but equally variable. Furthermore, from these data, it is possible to infer that a minimum of five estimations are necessary per individual to estimate the true mean value of urine albumin excretion with reasonable confidence.

Adolescent↗
PubMed1989

Autosomal recessive polycystic kidney disease.

The clinical features of 55 cases of autosomal recessive polycystic kidney disease (ARPCKD) have been reviewed. Each had evidence of ARPCKD. The outcomes of 87% were known; 24 had died. Twenty-four of 31 were seen between 1980 and 1986; 7 could not be traced. Forty-five percent presented under 1 month; 38% between 1 month and 1 year; and 9 cases over 1 year. Hyponatraemia occurred in 15 out of 19 aged less than 3 months; hypertension occurred in 65%; splenomegaly in 47% of those surviving more than 3 months. Portocaval shunts were done in 5 aged 2-12 years. Thirteen died of renal failure, 6 under 1 year, and 7 between 1 year and 13 years. Life-table survival rates calculated from birth revealed that 86% were alive at 3 months, 79% at 1 year, 51% at 10 years, and 46% at 15 years. Calculations based on patients who survived to 1 year of age showed that 82% were alive at 10 years and 79% at 15 years. These results reveal an improved prognosis for a condition once assumed to be fatal.

Child↗
PubMed1989

Upper esophageal sphincter opening and modulation during swallowing.

Studies were done on 8 normal subjects with synchronized videofluoroscopy and manometry to facilitate a biomechanical analysis of upper esophageal sphincter opening and volume-dependent modulation during swallowing. Movements of the hyoid and larynx, dimensions of sphincter opening, and intraluminal sphincter pressure were determined at 1/30th-s intervals during swallows of 1, 5, 10, and 20 ml of liquid barium. Our analysis subdivided upper esophageal sphincter activity during swallowing into five phases: (a) relaxation, (b) opening, (c) distention, (d) collapse, and (e) closure. Sphincter relaxation occurred during laryngeal elevation and preceded opening by a mean period of 0.1 s. Opening occurred as the sphincter was pulled apart via muscular attachments to the hyoid such that the hyoid coordinates at which sphincter opening and closing occurred were constant among bolus volumes. Sphincter distention after opening was modulated by intrabolus pressures rather than graded hyoid movement. The generation of intrabolus pressure coincided with the posterior thrust of the tongue that culminated in pharyngeal wall contact and the initiation of pharyngeal peristalsis. Larger volume swallows were associated with greater intrabolus pressure and increased bolus head velocity. The duration of sphincter opening increased in conjunction with a prolongation of the anterior-superior excursion of the hyoid and a delay in the onset of pharyngeal peristalsis (the event that determined the timing of sphincter closure). We conclude that transsphincteric transport of increasing swallow bolus volumes is accomplished by modulating sphincter diameter, opening interval, and flow rate (reflected by bolus head velocity). Furthermore, upper esophageal sphincter opening is an active mechanical event rather than simply a consequence of cricopharyngeal relaxation.

Adult↗
PubMed1989

Renal tubular proteinuria and microalbuminuria in diabetic patients.

The urinary extraction of albumin, retinol binding protein, and N-acetyl-beta-D-glucosaminidase were studied in 60 children with insulin dependent diabetes mellitus and in 45 normal children to find out whether the renal tubules played a part in causing the early increase in urinary excretion of albumin that occurs in diabetes mellitus. Two overnight urine samples were collected and the protein excretion measured and expressed as the geometric mean of the protein to creatinine ratio (urinary albumin:creatinine ratio, urinary retinol binding protein:creatinine ratio, and urinary N-acetyl-beta-D-glucosaminidase:creatinine ratio, respectively). The excretion of all three proteins was significantly higher in the diabetic children with 15 (25%) of urinary albumin:creatinine ratio, 16 (27%) of urinary retinol binding protein:creatinine ratio, and 43 (72%) of urinary N-acetyl-beta-D-glucosaminidase:creatinine ratio values being above the normal range. Significant correlations were observed between urinary albumin:creatinine ratio and urinary retinol binding protein:creatinine ratio, urinary albumin:creatinine ratio and urinary N-acetyl-beta-D-glucosaminidase:creatinine ratio, and urinary retinol binding protein:creatinine ratio and urinary N-acetyl-beta-D-glucosaminidase:creatinine ratio. There were also significant correlations between glycated haemoglobin 1c (HbA1c) and these proteins, especially N-acetyl-beta-D-glucosaminidase. No correlations were observed with the fractional excretion of sodium, flow rate of urine, glomerular filtration rate, or blood pressure. These data show that tubular abnormalities are present early in the course of insulin dependent diabetes mellitus and suggest that the early increase in urinary excretion of albumin may be at least partly tubular in origin, and that glycaemic control may influence this aspect of proximal tubular function.

Acetylglucosaminidase↗
PubMed1989

Sodium transport in erythrocytes: differences between normal children and children with primary and secondary hypertension.

The following measurements were made in normal children, children with primary hypertension, and children with secondary hypertension: erythrocyte intracellular sodium concentration, total sodium efflux rate constant, and maximum binding of ouabain to erythrocytes reflecting the number of sodium/potassium adenosine triphosphatase pump sites. Children with primary hypertension had a significantly higher mean erythrocyte intracellular sodium concentration (8.2 compared with 6.6 and 6.7 mmol/l cells), and significantly lower total sodium efflux rate constant (0.5071 compared with 0.6983 and 0.6197) and maximum binding of ouabain to erythrocytes (9.1 compared with 11.7 and 11.0 nmol/l cells) than normal children and children with secondary hypertension, respectively.

Adolescent↗
PubMed1989

The captopril test: an aid to investigation of hypertension.

Twenty three children aged from 5 to 16 with mild to moderate hypertension were investigated using the orally active angiotensin converting enzyme inhibitor captopril. Falls in both systolic and diastolic blood pressure after a single dose of captopril were significantly correlated with initial plasma renin activity. In addition, some information about the aetiology of hypertension was deduced from the renin response to captopril. The blood pressure response to captopril is a useful screening test for renin dependent hypertension in childhood.

Adolescent↗
PubMed1989

Early markers of the renal complications of insulin dependent diabetes mellitus.

We investigated the associations between albuminuria, metabolic control, glomerular filtration, blood pressure, and platelet function in children with insulin dependent diabetes mellitus. The geometric mean (95% tolerance levels) albumin excretion (expressed as the geometric mean albumin to creatinine ratio on two overnight urine collections (UA/UC], in 60 diabetic children was 0.72 (0.80-6.9) mg/mmol, significantly greater than in 45 normal children (geometric mean 0.41 (0.14-1.17]. Mean (SD) glomerular filtration rate, measured by 51Cr edetic acid clearance during constant infusion, was significantly greater in diabetic children (129 (20) ml/min/1.73 m2) compared with normal controls (109 (13]. Mean (SD) renal length for height standard deviation score was +0.25 (1.1); systolic blood pressure standard deviation score was 0.15 (0.65), and diastolic blood pressure was 0.51 (0.82). Spontaneous platelet aggregation, expressed as percentage fall in platelet count in stirred whole blood after 2 minutes was 17.8 (9.2)% in the diabetic compared with 12.3 (7.9)% in normal children. UA/UC correlated with renal length and of the children with UA/UC above the normal range, 70% also had a glomerular filtration rate above the normal range. There was a weak correlation between UA/UC and glycated haemoglobin (HbA1c). All children with spontaneous platelet aggregation above normal had had diabetes for more than seven years. These cross sectional data define some of the early markers and inter-relationships that may be important in the development of nephropathy.

Adolescent↗
PubMed1988

Erythrocyte sodium transport in Bartter's syndrome.

Erythrocyte sodium transport was evaluated by measurement of intracellular Na concentration (ICNa), 22Na efflux rate constant (NaERC) and 3H-ouabain binding (BMax) (reflecting the number of Na/K ATPase pump sites) in 9 children with Bartter's syndrome compared to controls (children and adults) and children with various forms of salt wasting disease. There were no differences between control children and adults. In untreated Bartter's syndrome ICNa was significantly increased with NaERC and BMax significantly decreased compared to findings in controls and patients with other salt wasting disease. On prostaglandin synthetase inhibitor (Indomethacin) therapy, ICNa decreased but remained higher than in controls, NaERC increased to normal values but BMax remained low. These data support the view that there is a widespread defect in membrane electrolyte transport in Bartter's syndrome but suggest that the benefit of indomethacin therapy is not manifest via an effect on Na/K ATPase.

Adolescent↗
PubMed1987

Use of oxidizing dyes in combination with 2-cyanocinnamic acid to enhance hyperthermic cytotoxicity in L929 cells.

Two widely used oxidizing dyes, 2,3,5-triphenyltetrazolium chloride and methylene blue, can greatly potentiate hyperthermic cytotoxicity when administered simultaneously with 2-cyanocinnamic acid. The same compounds are virtually nontoxic to L929 cells if administered alone at 42 degrees C or in combination with 2-cyanocinnamic acid at 37 degrees C. Cytotoxicity was synergistically enhanced by the combined regimens after 3 h of heat exposure. Quercetin, a bioflavonoid known to enhance hyperthermic cytotoxicity, also acts synergistically when administered in combination with 2-cyanocinnamic acid and this effect is apparent after 1 h of heat exposure. Since these compounds do not greatly interfere with pyruvate metabolism at either normal or heat shock temperatures, a mechanism of action based on depletion of NAD(P)H is considered.

Animals↗
PubMed1987

cDNAs for the postsynaptic 43-kDa protein of Torpedo electric organ encode two proteins with different carboxyl termini.

Postsynaptic membranes isolated from Torpedo electric organ are highly enriched in the nicotinic acetylcholine receptor and a nonreceptor protein of 43 kDa; the distribution of the 43-kDa protein and the receptor is coextensive in the electrical membrane. As a first step in understanding the regulation of 43-kDa protein expression, we have isolated and characterized 43-kDa protein cDNAs. A lambda gt11 cDNA library was constructed from Torpedo californica electric organ mRNA and screened with a pool of 26-mer oligonucleotides encoding a short tryptic fragment of the 43-kDa synaptic protein. Positive clones were purified and sequenced; the amino acid sequences were deduced, and they matched chemically determined protein sequences of the 43-kDa protein. Two distinct classes of cDNAs were obtained; one class encoded a 43-kDa protein of 389 amino acids with a calculated molecular mass of 43,988 daltons, and another class encoded a second 43-kDa protein containing 23 additional amino acids at the C terminus. Therefore, it appears that two 43-kDa proteins with different carboxyl termini are encoded by separate mRNAs. Consistent with this idea, blot hybridization analysis revealed multiple polyadenylylated 43-kDa mRNAs in electric organ. One polyadenylylated mRNA of approximately equal to 2.0 kilobases in length was apparent in both embryonic day-11 chick muscle and the mouse muscle cell line BC3H1.

Amino Acid Sequence↗
PubMed1987

Five year prospective study of plasma renin activity and blood pressure in patients with longstanding reflux nephropathy.

Eight of 100 normotensive children who had pyelonephritic scarring secondary to urinary infection and vesicoureteric reflux were found in an earlier study to have increased plasma renin activity (PRA). Because the risk of these patients becoming hypertensive is between 10% and 20% and because renin activity may play a part in the pathogenesis of the hypertension, PRA and blood pressure were studied in 98 of the original group after five years of follow up. Two patients could not be traced, and other factors that might influence blood pressure or PRA led us to exclude 13 others, 10 of whom were girls taking oral hormonal contraceptives. Increased PRA was found in 11 of the remaining 85 patients but not in five of the eight patients with increased PRA in the first study. Of eight children identified as hypertensive in the follow up study, only three had had increased PRA five years previously. In normal children PRA decreases with age. In the initial study this tendency was less pronounced in children with renal scars, and in the follow up study it was reversed. This was also confirmed by PRA standard deviation scores, which showed a significant increase in PRA during the five years. PRA tends to rise in patients with pyelonephritic scars as they grow older. There was no direct correlation between blood pressure and PRA, plasma creatinine concentration, or degree of scarring. Analysis of blood pressure standard deviation scores, however, suggested an excessive rise in blood pressure during the five years.

Adolescent↗
PubMed1987

Structure-anticonvulsant activity relationships of cannabidiol analogs.

Cannabidiol (CBD) exhibits anticonvulsant activity in experimental animals and in man. As part of a structure-activity study, analogs were prepared wherein the terpene unit, the aryl unit, and/or the side chain were modified. Thus, several pinenyl and carenyl derivatives, aryl ethers and acetates, and a variety of 1",1"-dialkylhexyl and 1",1"-dialkylheptyl analogs were synthesized. The compounds were evaluated for anti-convulsant activity in seizure susceptible (AGS) rats and for neurotoxicity in the rat rotorod (ROT) test. Comparisons of stereoisomers of CBD and several analogs revealed a general lack of stereoselectivity for anticonvulsant and other CNS properties of this class of compounds.

Animals↗
PubMed1986

A universal oligonucleotide probe for acetylcholine receptor genes. Selection and sequencing of cDNA clones for the mouse muscle beta subunit.

A region of 25 nucleotides is highly conserved in genes coding for the alpha, beta, gamma, and delta subunits of the nicotinic acetylcholine receptor (AChR) of human, mouse, calf, chicken, and Torpedo. Based on this observation, a 2-fold degenerate oligonucleotide was synthesized and used as a probe to screen a cDNA library made from a mouse myogenic cell line. Clones coding for the beta, gamma, and delta subunits were identified by the probe. The protein sequence deduced from the beta subunit clones codes for a precursor polypeptide of 501 amino acids with a calculated molecular weight of 56,930 daltons, which includes a signal peptide of 23 amino acids. The protein sequence and structural features of the beta subunits of mouse, calf, and Torpedo are conserved. A clone coding for the mouse gamma subunit was isolated, and its identity was confirmed by alignment of its sequence to previously published cDNA sequences for the mouse and calf gamma subunits. The clone contained approximately 200 nucleotides more at its 3' end untranslated region than a mouse gamma clone recently described. Northern blot analysis, utilizing as probes these beta and gamma subunit cDNAs and previously characterized alpha and delta subunit cDNAs, shows that the steady-state levels of the four AChR mRNAs increase coordinately during terminal differentiation of cultured C2 and C2i mouse myoblasts. The increase in mRNA levels can account for the rise of cell surface receptors during myogenesis and suggests that the muscle AChR genes may be regulated during development by a common mechanism. Utilization of this oligonucleotide probe should prove useful for screening a variety of libraries made from different species and tissues which are known to express AChRs.

Amino Acid Sequence↗