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Biomedical subjects

P K Mehta

Publications and source records attributed to P K Mehta.

At least 37 records · Page 2Linked to original sources
PubMed1989

Assay for aliphatic amino acid decarboxylases by high-performance liquid chromatography.

A sensitive and rapid assay for aliphatic amino acid decarboxylases based on separation of the product from the substrate by ion-pairing reversed-phase high-performance liquid chromatography and subsequent fluorometric detection has been developed. The resolution of substrates and products of seven amino acid decarboxylases, namely, arginine, aspartate, 2,6-diaminopimelate, histidine, glutamate, lysine, and ornithine decarboxylase, is complete within 15 to 35 min of isocratic elution. The limit of detection for the product is 40 pmol. The applicability of the procedure was assessed with glutamate decarboxylase. The formation of the product 4-aminobutyrate proved to be linear with time and protein concentration. The method allows the time course of the reaction to be followed in a single assay and works well with crude extracts of bacteria or tissues.

Carboxy-Lyases↗
PubMed1989

Activation of mouse peritoneal macrophages by mannophosphoinositides of mycobacteria.

Peritoneal macrophages isolated from mannoside-methylated bovine serum albumin (MBSA)-immunized mice showed significantly enhanced phagocytosis of Mycobacterium smegmatis compared to control or MBSA-immunized groups. Immune macrophages also exhibited bacteriostatic activity against M. smegmatis. Pretreatment of mycobacteria with mannoside antibodies did not further alter the phagocytosis and bacteriostatic effect of immune macrophages.

Animals↗
PubMed1989

Comparative evaluation of the diagnostic significance of circulating immune complexes and antibodies to phosphatidylinositomannosides in pulmonary tuberculosis by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay was developed to detect circulating immune complexes (CIC) and antibodies to phosphatidylinositomannosides (PIM) of mycobacteria for the diagnosis of pulmonary tuberculosis. Identification of PIM in CIC of smear and culture positive (SPCP) cases revealed 88% sensitivity and antibodies to PIM were detected in circulation in 94% cases. The smear negative and culture positive (SNCP) group had 67% positivity with regards to PIM in CIC and 83% for antibodies to PIM in circulation. In the smear negative and culture negative (SNCN) group, 40% samples were found to have PIM in CIC and 20% exhibited antibodies to PIM. The high degree of sensitivity was observed with both antigen detection in CIC and antibodies to PIM in circulation.

Antibodies, Bacterial↗
PubMed1988

Protective immunity to experimental tuberculosis by mannophosphoinositides of mycobacteria.

Mannophosphoinositides isolated from mycobacterial cells were found to induce both humoral and cell-mediated immune responses in mice when injected as mannoside-methylated bovine serum albumin (MBSA) complexes. Immunization of mice with mannoside-MBSA complexes elicited significant protection against challenge with LD50 dose of M. tuberculosis H37Rv as revealed by high survival rate, low values of root-specific lung weight, lung densities and colony forming units recovered from lung, liver and spleen, compared to the nonimmunized group. These observations were further substantiated by histopathological studies. The protective immunity elicited by mannoside-MBSA complexes against challenge with M. tuberculosis H37Rv was mediated by the cooperation of T-B cells, as shown by the passive transfer of immune cells/sera into syngeneic sublethally irradiated recipient mice.

Animals↗
PubMed1988

Serodiagnostic potentialities of enzyme-linked immunosorbent assay (ELISA) using mannophosphoinositides of Mycobacterium tuberculosis H37Rv.

The serological response to mannophosphoinositides of Mycobacterium tuberculosis H37Rv and to tuberculin-purified protein derivative (PPD) was examined by enzyme-linked immunosorbent assay (ELISA) in patients suffering from tuberculosis and related diseases. In sputum positive cases 94% samples were found to be positive to mannoside antigens and 77% to PPD, while in sputum negative cases, 71% of samples gave a positive reaction to mannosides and 54% to PPD. The high specificity of mannoside ELISA was demonstrated to be 97% in healthy individuals and 100% in patients suffering from other respiratory diseases, whereas PPD ELISA was 84% and 82% in healthy and infected patients respectively. Thus, ELISA is more specific and sensitive for mannosides than for PPD for the diagnosis of tuberculosis. However, antibodies to mannosides and PPD were detected in lepromatous as well as tuberculoid leprosy patients.

Antibodies, Bacterial↗
PubMed1981

Drug-induced papillary necrosis: electrolyte excretion and nephron heterogeneity.

The functional expression of papillary necrosis was investigated in rats following administration of 2-bromoethylamine hydrobromide (BEA). The percentage of filtering superficial and juxtamedullary nephrons was assessed using the qualitative Hanssen technique. There was a marked decrease in the percentage of filtering juxtamedullary nephrons 24 h after the induction of papillary necrosis (as compared with control rats), which was blunted in salt-loaded animals. The percentage of filtering superficial nephrons was the same in all three groups. BEA administration to normal rats was associated with a significant increase in sodium, chloride, phosphate, and calcium excretion. BEA administration to rats on a chloride-restricted diet was associated with chloride wastage. These animals also failed to adapt to a low chloride diet as late as 7 days after the administration of BEA. The phosphaturia observed in intact rats treated with BEA was abolished by parathyroidectomy. BEA-treated rats were able to adapt to a low phosphate diet and to a low magnesium diet. These data demonstrate that papillary necrosis is associated with profound impairment of juxtamedullary nephron filtration and with chloride wastage. In the absence of the papillary structures adaptation to phosphorus or magnesium deprivation is still possible.

Animals↗
PubMed1979

Functional characterization of drug-induced experimental papillary necrosis.

The functional expression of papillary necrosis was investigated with a model of drug-induced papillary necrosis. Bromoethylamine hydrobromide (BEA) administration to rats uniformly resulted in the development of papillary necrosis. All studies were performed 24 hours after BEA administration with the exception of the electrolyte balance studies, which were performed during the 72 hours after the induction of papillary necrosis. GFR was not different between BEA-treated and sham rats. BEA-treated rats had a significantly lower maximal urine osmolality and free water reabsorption than did sham rats. Renal tissue concentrations of sodium, potassium, and water were not different between BEA-treated and sham rats. During water diuresis, free water clearance was not significantly different between the two groups. During sodium bicarbonate administration, maximal bicarbonate reabsorption and urine-blood Pco2 gradient (at comparable urine bicarbonate concentrations) were not significantly different between the two groups. During sodium sulfate infusion, there was no difference in minimum urine pH, ammonium excretion, and net acid excretion between chronically acidotic BEA-injected and sham rats. In rats on "zero" sodium intake, BEA administration resulted in a significant increase in urine flow and sodium excretion, whereas sham rats remained in sodium balance. In rats with restriction of both sodium and chloride, BEA administration resulted in a significant wastage of sodium, chloride, and calcium. There was no difference in potassium excretion between BEA-treated and sham rats during hydropenia, bicarbonate administration, sodium sulfate infusion, or ingestion of a normal potassium diet. When potassium intake was restricted to "zero," BEA-treated rats developed potassium wastage; when potassium intake was increased to 21 mEq/day, BEA-treated rats had a significantly lower potassium excretion than did sham rats. These findings may result from alterations in collecting duct transport, but damage to deep medullary structures may also contribute.

Animals↗
PubMed1979

Studies on saprozoonosis. I. A survey on Aspergillus species with special reference to occupational habits.

A comprehensive survey of Aspergillus species has been carried out among different cattle and donkey handlers. A total of 300 pharyngeal swabs of different subjects including 100 control and 100 each from cattle and donkey handlers was investigated. All the subjects were found healthy. Among the species of Aspergillus, the number of A. flavus appeared higher followed by A. fumigatus, still lower number was encountered with other species like A. nidulans and A. glaucus. In order to establish the saprozoonotic relationship, soil and air samples of various animal sheds were also analyzed. It was found that the total number of isolates of Aspergillus species from animal sheds were always higher compared to the control samples. None of the A. flavus strains obtained from air samples produced aflatoxin. Histopathological changes in Swiss mice caused by intratail vein administration of spores of Aspergillus species have been investigated.

Air Microbiology↗
PubMed1979

Plasma concentrations of propranolol and 4-hydroxypropranolol during chronic oral propranolol therapy.

1 The plasma levels of propranolol and 4-hydroxypropranolol have been measured in 17 hypertensive patients receiving chronic oral therapy with propranolol. 2 The range of plasma propranolol concentrations was from 5.3 to 300 ng/ml, and that of 4-hydroxypropranolol was from 2.1 to 36.0 ng/ml. 3 The mean (+/- s.d.) plasma concentration ratio of 4-hydroxypropranolol to propranolol was 0.130 (+/- 0.005); however, a very wide range was observed with individual values ranging from 0.057 to 0.241. 4 A statistically significant correlation was observed between the plasma concentration of 4-hydroxypropranolol and that of propranolol. 5 Propranolol and 4-hydroxypropranolol plasma concentrations were each significantly, but poorly, correlated with daily propranolol dose. 6 The clinical significance of the results has been discussed.

Adult↗
PubMed1979

Interaction of amiloride and lithium on distal urinary acidification.

The interaction of amiloride and LiCl administration on renal HCO3 handling was studied in hydropenic rats. Amiloride administration resulted in a significant increase in Na, Cl, and HCO3 excretion, whereas K excretion decreased significantly. LiCl administration resulted in a significant increase in Na, Cl, K, and HCO3 excretion. LiCl administration to animals receiving amiloride led to a significant increase in HCO3 excretion but failed to cause an increase in Na or K excretion. Addition of amiloride to animals receiving LiCl resulted in a significant increase in Na and HCO3 excretion. The net increase in fractional HCO3 excretion seen in this group was greater than that seen in all other groups. The finding that the net increase in FEHCO3 was greater in animals receiving amiloride after administration of LiCl than in animals receiving LiCl after amiloride administration indicates that amiloride blunted the effect of LiCl on HCO3 excretion. Administration of amiloride to both normal rats and to rats infused with Li during HCO3 administration resulted in a significant decrease in U-B Pco2 which could not be explained by the decrease in urine HCO3 concentration. These data demonstrate that amiloride inhibits distal acidification in vivo. LiCl administration also resulted in a decrease in U-B Pco2 which could be explained by the decrease in urine HCO3 concentration. LiCl administration also resulted in a decrease in TcH2O which could be prevented by prior administration of amiloride. These data indicate that amiloride blunts the effect of LiCl on urinary acidification, an effect similar to that observed on urinary concentration. These data suggest that the effect of Li on urinary acidification is in part dependent on Li entry into the cell.

Amiloride↗
PubMed1977

Effect of furosemide on renal handling of glucose in the rat.

Clearance and intratubular microinjection studies were performed in rats during extracellular volume expansion before and after furosemide administration to evaluate renal tubular transport of glucose. Three groups of animals were studied: group I, intact rats; group II, acutely thyroparathyroidectomized rats; and group III, thyroparathyroidectomized rats receiving parathyroid extract after a control period. In all groups furosemide caused a significant increase in the urinary flow rate and sodium excretion. There was no significant change in filtered glucose and glucose excretion. After early distal tubular injections of [14C]glucose, recovery was complete both before and after furosemide infusion. Furosemide had no effect on [14C]glucose recovery after the late proximal injection. These results indicate that furosemide has no effect on the renal handling of glucose in normoglycemic rats. There is no evidence for glucose reabsorption in the nephronal segments distal to the early distal tubular segment in this experimental state. Our data suggest, but do not prove, that no glucose is transported by the rat nephron beyond the pars recta during normoglycemia.

Animals↗
PubMed1977

The critical importance of urinary concentrating ability in the generation of urinary carbon dioxide tension.

Measurement of urine to blood (U-B) carbon dioxide tension (P(CO2)) gradient during alkalinization of the urine has been suggested to assess distal H(+) secretion. A fact that has not been considered in previous studies dealing with urinary P(CO2) is that dissolution of HCO(3) in water results in elevation of P(CO2) which is directly proportional to the HCO(3) concentration. To investigate the interrelationship of urinary HCO(3) and urinary acidification, we measured U-B P(CO2) in (a) the presence of enhanced H(+) secretion and decreased concentrating ability i.e., chronic renal failure (CRF), (b) animals with normal H(+) secretion and decreased concentrating ability, Brattleboro (BB) rats, and (c) the presence of both impaired H(+) secretion and concentrating ability (LiCl treatment and after release of unilateral ureteral obstruction). At moderately elevated plasma HCO(3) levels (30-40 meq/liter), normal rats achieved a highly alkaline urine (urine pH > 7.8) and raised urine HCO(3) concentration and U-B P(CO2). At similar plasma HCO(3) levels, BB rats had a much higher fractional water excretion and failed to raise urine pH, urine HCO(3) concentration, and U-B P(CO2) normally. At a very high plasma HCO(3) (>50 meq/liter), BB rats raised urine pH, urine HCO(3) concentration, and U-B P(CO2) to the same levels seen in normals. CRF rats failed to raise urine pH, urine HCO(3), and U-B P(CO2) normally at moderately elevated plasma HCO(3) levels; at very high plasma HCO(3) levels, CRF rats achieved a highly alkaline urine but failed to raise U-B P(CO2). Dogs and patients with CRF were also unable to raise urine pH, urine HCO(3) concentration, and U-B P(CO2) normally at moderately elevated plasma HCO(3) levels. In rats, dogs, and man, U-B P(CO2) was directly related to urine HCO(3) concentration and inversely related to fractional water excretion. At moderately elevated plasma HCO(3) levels, animals with a distal acidification defect failed to raise U-B P(CO2); increasing the plasma HCO(3) to very high levels resulted in a significant increase in urine HCO(3) concentration and U-B P(CO2). The observed urinary P(CO2) was very close to the P(CO2) which would be expected by simple dissolution of a comparable amount of HCO(3) in water. These data demonstrate that, in highly alkaline urine, urinary P(CO2) is largely determined by concentration of urinary HCO(3) and cannot be used as solely indicating distal H(+) secretion.

Acid-Base Equilibrium↗
PubMed1975

High-dose bolus urography. A superior technique in advanced renal failure.

High-dose bolus urography was evaluated in 38 patients with severe renal failure. Iothalamate meglumine (Conray 60) (2 ml/kg of body weight) was injected within one minute and nephrotomograms were taken for 30 minutes, with delayed films until 24 hours. Immediate nephrograms were obtained in all cases. The collecting systems, seen in 29 cases, were dilated in three. In the rest, obstruction could be ruled out by a combination of roentgenographic criteria. No untoward reactions occurred, and all the required information was obtained within 30 minutes. The results were superior to plain nephrotomography or infusion pyelography. We conclude that bolus nephrotomography is the procedure of choice in the investigation of severe renal failure.

Acute Kidney Injury↗