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Biomedical subjects

A C Parekh

Publications and source records attributed to A C Parekh.

At least 19 recordsLinked to original sources
PubMed1987

Unique proliferation-associated marker expressed on activated and transformed human cells defined by monoclonal antibody.

The expression, tissue distribution, and preliminary characterization of a cell surface molecule, apparently a glycolipid, recognized by a monoclonal antibody, anti-PAA, were described. This antibody (anti-PAA) was produced by the fusion of myeloma cells NS-1 with spleen cells from a BALB/c mouse, which were sensitized with activated human T-cells generated by allogeneic stimulation in mixed-lymphocyte culture (MLC). Resting human peripheral blood T-cells, B-cells, and monocytes demonstrated weak anti-PAA binding. Binding of proliferating T-cells (phytohemagglutinin- and MLC-activated T-cells) and thymocytes to anti-PAA was two to six times greater than that of resting T-cells. A fifteenfold-increased binding was observed with acute lymphocytic leukemia T-cell lines. Epstein-Barr virus-transformed B-cell lines bound anti-PAA up to sixteenfold greater than resting B-cells. Tumor cell lines of various nonlymphoid origins demonstrated marked reactivity with this antibody. Both benign and malignant cells in hyperplastic tissues, of various origins, bound anti-PAA, whereas their normal, nonproliferating counterparts did not. Normal proliferating cells in these tissues, including cells of the placental chorionic villi and trophoblasts, also bound anti-PAA. Of all lymphoid and nonlymphoid cell lines examined, only chronic lymphocytic leukemia (CLL) cells and some cell lines derived from Burkitt's lymphoma showed weak or no binding. This antibody also failed to react with a variety of nonprimate cell lines. Anti-PAA antibody did not immunoprecipitate any protein from lymphoid tumor cell lines to which it demonstrated a quantitatively high degree of binding, nor did protease treatment of these lines decrease antibody binding. Anti-PAA did, however, bind to glycolipids extracted from these cell lines. Binding of this monoclonal antibody to a minor neutral glycolipid, isolated from the erythroleukemia cell line K562, was about sixfold greater than that of any other K562 neutral glycolipid or ganglioside. Anti-PAA demonstrated weak or undetectable binding to purified, predominant, lymphoid cell membrane's neutral glycolipids and gangliosides. The monoclonal antibody anti-PAA appeared, therefore, to recognize a unique, proliferation-associated, neutral glycolipid present on normal as well as on benign and malignant proliferating cells. The antigen appeared to be universally expressed on proliferating cells from all human tissues with the exception of some Burkitt's cell lines and CLL cells. Nonhuman cell lines, except those for closely related primates, did not express PAA.

Antibodies, Monoclonal↗
PubMed1977

Determination of serum creatinine by reaction with methyl-3,5-dinitrobenzoate in Methyl Sulfoxide.

Creatinine in serum is determined with a new reagent system consisting of methyl-3,5-dinitrobenzoate and tetramethyl ammonium hydroxide in 50% methyl sulfoxide. The method shows excellent correlation with manual and automated alkaline picrate procedures and has comparable sensitivity. The proposed method has advantages over the dinitrobenzoyl chloride assay system in terms of sensitivity, reagent stability and precision. The day-to-day coefficient of variation is 2.9-3.8%, while within day is 1.5-2.1%. The standard curve is linear beyond 20 mg/dl creatinine. Compared to the picrate method, the proposed assay is less than one half as susceptible to a combination of known interfering agents. Based on the present studies, it is recommended as an excellent alternative to the commonly used picrate procedures.

Acetoacetates↗
PubMed1977

On the mechanism of hypocholesterolemic action of amphotericin B in rat.

The transient hypocholesterolemia phenomenon observed in rats, injected i.v. with amphotericin B (1.5 mg/kg/day) for three weeks, was investigated by in vitro [14C] acetate incorporation into the liver cholesterol. The incorporation of acetate in liver slices of treated animals increased more than two-fold (p less than 0.02) when compared with controls.When amphotericin B was added in vitro to liver slices of control rats, the incorporation of acetate into cholesterol decreased to about 65% of that observed with the corresponding controls (p less than 0.01). The results are consistent with the hypothesis that initially amphotericin B causes inhibition of de novo cholesterol synthesis resulting in hypocholesterolemia which disappears on continued treatment possibly due to compensatory increased rate of cholesterol biosynthesis.

Amphotericin B↗
PubMed1977

Serum creatinine assay by use of 3,5-dinitrobenzoates: a critique.

Methyl-3,5-dinitrobenzoate and 3,5-dinitrobenzoyl chloride are demonstrated to react with creatinine through their conversion to 3,5-dinitrobenzoate. Analytical recovery of creatinine added to serum is improved by an "acid-supernate" modification, which is also much less susceptible to a combination of known interfering agents than is the picrate procedure. The "neutral-supernate" procedure shows negligible interference by cephalothin as compared to commonly used picrate procedures. Replacement of tetramethylammonium hydroxide by sodium hydroxide was also tested. The interrelationships between dimethyl sulfoxide concentration, recoveries of creatinine, and slopes of correlations (r greater than .992) of various dinitrobenzoate and picrate methods are critically assessed. Because of its precision, greater specificity, and other criteria, we recommend the methyl-3,5-dinitrobenzoate (or 3,5-dinitrobenzoic acid) neutral-supernate method for routine applications.

Cephalothin↗
PubMed1976

A new method for the determination of serum creatinine based on reaction with 3.5-dinitrobenzoyl chloride in an organic medium.

A new method for the determination of serum creatine, based on its reaction with 3,5-dinitrobenzoyl chloride in an organic medium is described. Various analytical parameters are studied and comparisons are made with the routine picrate procedures, as well as the dinitrobenzoic acid methods reported in the literature. On the basis of the data submitted, the proposed method is recommended for routine clinical use.

Colorimetry↗
PubMed1976

Interference of sodium azide with the quantitation of serum cholesterol: a comparative study.

Interference of sodium azide (employed widely as a preservative for serum) with six different cholesterol methods and two modified procedures is analyzed and compared. Sodium azide is shown to lower the serum cholesterol values of the iron-cholesterol methods from 5 to 50% at 0.1 g% azide, and from 60 to 95% at 1.0 g% azide concentration, depending on the method employed. This inhibition is independent of serum cholesterol concentration. Increased serum to reagent (v/v) ratio, i.e., increased azide concentration, caused increased depression of serum cholesterol values. Appropriate choice of low serum-to-reagent (v/v) ratio thus decreases the magnitude of the azide interference in the iron-cholesterol reaction to 3-10% for the precipitation procedures, and to 25% for the non-precipitation procedure at 0.1 g% azide concentration in serum.

Azides↗
PubMed1976

A new automated procedure for serum inorganic phosphorus.

1. The method of Parekh and Jung for determination of inorganic phosphorous in serum has been adapted for automation. One of the assets of the method is its unusually stable reagents. The automated procedure is highly accurate, sensitive, rapid and economic. Its other advantages are discussed in light of the literature.

Autoanalysis↗
PubMed1975

Steroid interference in iron-cholesterol reactions: a comparative study.

Interference from various physiological and non-physiological steroids in the spectrophotometric determination of cholesterol by the Zak method (ferric chloride) and the method of Parekh and Jung (ferric acetate) was quantitatively measured. Contribution of the steroids at the specific absorption maxima of the cholesterol assays was determined by employing the steroids (40 mg/dl) alone, or added to a serum pool of known cholesterol content. The results show that the method of Parekh and Jung is less influenced by the presence of steroids than the Zak method. Observations on the structural specificity of the iron-cholesterol reaction are discussed.

Binding Sites↗
PubMed1975

Effect of hamycin on plasma cholesterol of rat.

Hamycin, a polyene antibiotic, when administered orally with food or by a cannula or administered intraperitoneally produced a dose-dependent hypocholesterolemic effect on normal albino rats. A 50% decrease occurred in serum cholesterol level at 25-50 mg/kg oral dose of hamycin. No further decrease occurred in serum cholesterol level with increase in the oral dosage. Decrease in the serum cholesterol occurring with 0.5-1.0 mg/kg, ip dose of the antibiotic was similar to that observed with oral hamycin and suggest that the effect was possibly mediated through mechanisms other than those involving prevention of absorption of cholesterol through the gastrointestinal tract.

Administration, Oral↗
PubMed1975

Long-term effect of amphotericin B on serum cholesterol in the rat.

Amphotericin B (1mg/kg/day) was administered intravenously to rats for 30 days, with simultaneous sham (5% dextrose in saline) injections to control animals. After four treatments, serum cholesterol concentration among treated animals demonstrated a maximum decrease of 25% (p less than 0.005) from the control level. Serum cholesterol returned to control level after three more treatments, and no significant difference (p greater than 0.05) was observed in experimental animals, despite continued treatment thereafter. Various hematological and biochemical parameters were monitored at intervals during this period. Except for significantly elevated (p less than 0.001) plasma urea nitrogen in treated animals, no significant difference was observed between the control and treated animals with regard to other parameters. Gross examination at autopsy, followed by microscopic study, showed absence of organ pathology.

Amphotericin B↗
PubMed1972

Urinary inorganic phosphorus determinations.

The Parekh-Jung method for determination of inorganic phosphorus in serum was applied to its determination in urine. Accuracy is good. The mean percentage recovery of added phosphorus was 100.2%. Forty analyses of a sample gave a mean value of 46.71 mg/100 ml +/- 0.76 standard deviation (between-batch precision). The relative usefulness of the Parekh-Jung method compared with those other methods is discussed.

Humans↗