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Biomedical subjects

A B Patel

Publications and source records attributed to A B Patel.

At least 19 recordsLinked to original sources
PubMed2006

Renal colic during sexual intercourse: a unique presentation.

The average lifetime risk of renal stones has been reported to be in the range of 5-21%, and the majority of patients have recurrent stones (Tiselius et al. in Eur Urol 40:362-371, 2001). The peak incidence is between the fourth and fifth decades, and therefore generally active and working adults are most affected. Stones are usually formed in a calyx, and become symptomatic if they move to obstruct the upper urinary tract. In the majority of cases, there is no specific action which causes stone movement from a non-obstructing to an obstructing position. We present the first ever case report in the literature of an episode of renal colic during sexual intercourse. The role of percussion therapy and postural drainage are well established following shockwave lithotripsy (SWL) to enhance passage of lower pole stone fragments (Brownlee et al. in J Urol 143:1096, 1990), and it may well be the result of similar principles of motion and body positioning which caused the patient to present in this manner.

Adult↗
PubMed2001

Glutamine is the major precursor for GABA synthesis in rat neocortex in vivo following acute GABA-transaminase inhibition.

The objective of the present study was to assess the degree to which astrocytic glutamine provides carbon for net synthesis of GABA in the rat neocortex in vivo. Isotopic labeling of GABA and glutamate from astrocytic glutamine was followed in halothane anesthetized and ventilated rats during an intravenous infusion of [2-(13)C]glucose. A net increase in GABA was achieved by administration of the GABA-transaminase inhibitor, gabaculine to suppress catabolism of GABA and recycling of (13)C label. (13)C Percentage enrichments of GABA, glutamate and glutamine were assessed in tissue extracts using (13)C-edited (1)H nuclear magnetic resonance at 8.4 T. GABA levels increased 2.6 micromol/g at 2 h and 6.1 micromol/g at 5 h after gabaculine, whereas glutamate and glutamine decreased in toto by 5.6 micromol/g at 2 h and 3.1 micromol/g at 5 h. Selective enrichment of glutamine, glutamate, and GABA C3's over other carbon positions was observed consistent with a precursor role for astrocytic glutamine. Between 1 h (control) and 3 h (gabaculine-treated) of [2-(13)C]glucose infusion, (13)C percentage enrichment increased in glutamine C3 (from 3.2+/-0.5 to 7.0+/-0.9%), glutamate C3 (from 1.8+/-0.5 to 3.4+/-0.9%), and GABA C3 (from 2.7+/-1.6 to 4.8+/-0.4%). The measured incremental [3-(13)C]GABA concentration (0.15 micromol/g) was close to the predicted value (0.13 micromol/g) that would be expected if the increase in GABA were produced entirely from glutamine compared to glutamate (0.07 micromol/g) based on the average precursor enrichments between 1 and 3 h. We conclude that glutamine is the major source of GABA carbon in the rat neocortex produced acutely following GABA-T inhibition by gabaculine in vivo.

4-Aminobutyrate Transaminase↗
PubMed2001

Substance P (free acid) adopts different conformation than native peptide in DMSO, water and DPPC bilayers.

The conformation of substance P (free acid) (SPOH) has been investigated in dimethylsulfoxide (DMSO), water and dipalmitoylphosphotidylcholine (DPPC) bilayers by two-dimensional NMR and restraint molecular dynamics simulations. The observed NOE patterns for SPOH in these media are very much different from each other. Molecular modeling of the conformation of SPOH by incorporating NOEs as distance restraints shows wide differences in its conformation in three media. The main structural features for SPOH in DMSO are y-bends at Pro4 and Phe7 along with a non-specific bend around Lys3-Pro4-Gln5-Gln6, which are stabilized by Lys3CO-->Gln5NH, Gln6CO-->Phe8NH hydrogen bonding. The more flexible conformation of SPOH in water is transformed to an ordered structure after incorporation in DPPC bilayers. The conformation of SPOH in DPPC bilayers is characterized by gamma-bends at Pro4, Gln6 and Phe7, which are stabilized by hydrogen bonding between Lys3CO-->Gln5NH, Gln5CO-->Phe7NH and Gln6CO-->Phe8NH, respectively. The absence of biological activity in SPOH has been attributed to the absence of any helix like structure at the central residues and absence of any interresidue interaction with C-terminal OH group, in DPPC bilayers, a feature shown to be an important prerequisite for SP and SP agonists to bind to the NKI tachykinin receptor.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

Role of vitamin E in rheumatic chorea.

Rheumatic chorea is the sole neurologic manifestation of rheumatic fever. It is a debilitating illness lasting for weeks to months. Drugs like diazepam, haloperidol, chlorpromazine take four to six weeks for functional improvement and can cause serious side effects. The authors investigated the role of Vitamin E in reducing rheumatic chorea. A case series of patients of rheumatic chorea were administered Vitamin E in the dose 50 IU daily for fifteen days. The various clinical signs of rheumatic chorea were scored with MAIMS score (Modified Abnormal Involuntary Movement Scale score) which is used for tardive dyskinesia. No other drug for abnormal movements was used. In all the 4 patients who received vitamin E, there was remarkable change by 7th day and almost complete functional improvement by 14th day. Vitamin E is safer than the conventional drugs used for chorea in children. It was found effective in this case series. Its role needs further evaluation by a double-blind randomized controlled trial.

Child↗
PubMed1999

Interaction of 7-hydroxy-8-(phenylazo)1,3-naphthalenedisulfonate with bovine plasma albumin. Spectroscopic studies.

Interaction of Orange G (OG) with bovine plasma albumin (BPA) has been investigated using NMR, UV-visible absorption, CD, and fluorescence techniques. The bound conformation of OG is a compact structure with N9-N10 bond in a non-planar syn conformation. The binding causes a decrease in the 478-nm absorption band of OG. The analysis of the binding isotherm generated from UV-visible absorption measurements gives a dissociation constant of 10 microM and stoichiometry 1:1 for BPA.OG complex. Dissociation constant is invariant in the pH range 5.0-8.0 and is approximately 20 times higher at pH 4.0 than its value at pH 7.0. Near and far UV-CD studies indicate alterations in the helical content and in the tertiary structure of the protein on complexation. The binding induces (-) and (+) CD at 335 nm and 465 nm, respectively. The binding also results into an increase in the steady state fluorescence anisotropy of OG without affecting emission maximum and quantum yield. Fluorescence data indicate that quenching of Trp fluorescence by OG is static in nature and OG selectively binds near Trp-135. Observation of similar rotational correlation time for BPA and BPA.OG complex indicates that the overall globular structure of BPA remains unaltered on binding despite certain internal rearrangement in the protein structure.

Animals↗
PubMed1999

Identification of low-molecular-weight compounds in goat epididymis using multinuclear nuclear magnetic resonance.

Multinuclear nuclear magnetic resonance (NMR) (1H, 13C, and 31P) studies have been performed on aqueous solutions of lyophilysates of cell-free extract, epididymal fluid, and intact cells from caput and cauda regions of epididymis of sacrificed goats. Identification of low-molecular-weight compounds present in different maturation phases of spermatozoa has been carried out. Several low-molecular-weight compounds have been identified by assigning 600 MHz 1H NMR spectra with the help of two-dimensional homonuclear and heteronuclear correlation spectroscopy such as double quantum filtered correlation spectroscopy and heteronuclear single quantum correlation spectroscopy. Homonuclear coupling constants have also been used to get unambiguous assignments of resonances. NMR data were compared with those of standard samples measured at same pH and with those reported in the literature. Identification of several amino acids, carbohydrates, and lipids have been made and their presence has been discussed in relation to their relevance to sperm functions. The presence of beta-alanine and hypotaurine has been reported for the first time in goat epididymis.

Animals↗
PubMed1999

Replacement of phe(8) in substance P by tyr (Tyr(8)-SP) alters the conformation of the peptide in DMSO, water, and lipid bilayers.

The conformation of [Tyr(8)]SP (Y8SP) in dimethylsulfoxide (DMSO), water, and dipalmitoyl phosphatidylcholine (DPPC) bilayers has been investigated by two-dimensional nmr and molecular dynamics simulations. Molecular modeling of the conformation of Y8SP by incorporating nuclear Overhauser effects as distance restraints shows wide differences in its conformation in the three media. In DMSO, the main structural features are gamma-bends along with a nonspecific bend around Gln(6)-Phe(7)-Tyr(8). The random coil structure seen in water is transformed into a beta-turn around the segment Gln(5)-Gln(6)-Phe(7)-Tyr(8) when Y8SP is incorporated into DPPC bilayers. The lower biological activity of Y8SP compared to the native peptide (SP) has been attributed to the absence of any helix like structure at the central residues, a feature shown to be an important prerequisite for SP and SP agonists to bind to the neurokinin 1 tachykinin receptor.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1999

Arginine acts as a protective and reversal agent against glycolytic inhibitors in spermatozoa.

It is known that the amino acid arginine stimulates sperm motility and glycolytic activity. We have earlier studied its efficacy as a stimulator of glycolysis in goat spermatozoa under anaerobic conditions. Here, we have assessed the influence of arginine in reversing the impairment caused by glycolytic inhibitors, iodoacetamide and iodoacetic acid. Glycolysis has been monitored by measuring the consumption of 13C labeled glucose and the amount of 13C labeled lactate produced under different experimental conditions, using 13C NMR. It is observed that both L- and D-arginine are able to prevent and reverse the inhibitory action of glycolytic inhibitors. The reversal effect of arginine gives rise to about eight times higher metabolic activity as compared to the inhibited cells while structurally related amino acids such as nitro-arginine, homo-arginine, lysine and ornithine are ineffective. The energetics of spermatozoa as measured by 31P NMR show a reduction in ATP level in cells incubated with iodoacetamide. Treatment of these cells with both L- and D-arginine restores the ATP level. The results may have significance in the treatment of male infertility.

Animals↗
PubMed1998

Arginine activates glycolysis of goat epididymal spermatozoa: an NMR study.

The present study explores the mechanism underlying the action of L-arginine on the metabolic activity of spermatozoa. Goat epididymal spermatozoa were incubated with different concentrations of L-arginine to determine its effect on the utilization of glucose, fructose, and pyruvate. NMR techniques have been applied to elucidate the effect of L-arginine, L-lysine, and L-ornithine on the glycolysis of epididymal goat spermatozoa. Whereas 31P NMR has been used to estimate the change of pH in the presence of different concentrations of L-arginine, 13C NMR has been used to estimate the substrate consumption and lactate production. At optimal concentration of L-arginine, the forward metabolic rates have been found to increase by two to three times over control experiments. Arginine is not consumed in these reactions, but acts as an activator. Longitudinal relaxation time (T1) measurements indicate that the guanidino group of L-arginine plays an active role in binding to cells. The amino acid L-lysine is less effective, and L-ornithine is ineffective.

Animals↗
PubMed1994

Effects of chronic manganese toxicity on tissue levels and urinary excretion of nicotinamide nucleotides in rats.

Male rats were exposed to manganese sulphate i.p. daily for a period of four weeks to see its effects on tissue levels and urinary excretion of total nicotinamide nucleotides (TNN). Increased levels of TNN were observed in blood and brain while the levels were found to be decreased in liver. There was a progressive increase in the excretion of TNN during the experimental period. TNN levels in blood and urine might serve as useful biological indicators of Mn toxicity.

Animals↗