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Biomedical subjects

N Balasubramanian

Publications and source records attributed to N Balasubramanian.

At least 37 records · Page 2Linked to original sources
PubMed1993

Colorectal cancer imaging with iodine-123-labeled CEA monoclonal antibody fragments.

This prospective, randomized multicenter study in 62 patients was designed to evaluate the efficacy and safety of radioimmunodetection (RAID) with 123I-labeled fragments, F(ab')2 and Fab', of IMMU-4, an anti-CEA monoclonal antibody (Immu-RAID-CEA). It was found that ImmuRAID-CEA was safe and disclosed colorectal cancer sites at least 1 cm in size. The positive predictive value by lesions was 77% initially, and increased to 91% after 7 mo of follow-up. Only one patient developed a low level of HAMA. In 17 patients with 32 surgically confirmed lesions, there were 9% true-positive lesions for CT when RAID was false-negative, and 22% for RAID when CT was false-negative. Either CT or RAID detected all 32 lesions. In this small series, therefore, RAID was shown to complement CT findings by confirming suspected tumors and disclosing new lesions which had previously been occult.

Adult↗
PubMed1992

Cholinesterases exhibiting aryl acylamidase activity in human amniotic fluid.

Acetylcholinesterase (EC 3.1.1.7) and butyrylcholinesterase (EC 3.1.1.8) in human amniotic fluid were estimated in the presence of selective inhibitors. Amniotic fluid cholinesterases (mixture of acetylcholinesterase and butyrylcholinesterase) purified by procainamide-Sepharose affinity chromatography exhibited aryl acylamidase activity which was sensitive to serotonin inhibition (a property of aryl acylamidases associated with both acetyl- and butyrylcholinesterases) and tyramine activation (shown exclusively by aryl acylamidase associated with butyrylcholinesterase). Tyramine activation was unaffected in the presence of the selective acetylcholinesterase inhibitor BW284C51 whereas it was abolished in the presence of the selective butyrylcholinesterase inhibitor ethopropazine, suggesting the presence of both types of aryl acylamidases in amniotic fluid, one associated with acetylcholinesterase and the other associated with butyrylcholinesterase. Butyrylcholinesterase and the associated aryl acylamidase activity in the affinity purified enzyme was selectively immunoprecipitated by a polyclonal antibody raised against human serum butyrylcholinesterase. Estimation of the activity ratio of acetylcholinesterase to butyrylcholinesterase in a few samples of amniotic fluid showed that this could vary depending on the butyrylcholinesterase arising from contaminating blood in the samples. Gel electrophoresis under non-denaturing conditions and enzyme staining showed that butyrylcholinesterase band was detectable on the gel in all the samples whereas acetylcholinesterase band was below detectable levels in normal samples but visible in samples from pregnancies of neural tube defect fetuses. It is suggested that the use of selective cholinesterase inhibitors along with gel electrophoresis and immunoprecipitation studies may be useful in the assessment of cholinesterase activities in human amniotic fluid.

Acetylcholinesterase↗
PubMed1992

Studies on variations of glycoproteins and lysosomal hydrolases in human uterine cervical carcinoma.

Variations of glycoprotein components such as hexose, hexosamine, and sialic acid and lysosomal glycosidases such as beta-D-glucosidase, beta-D-galactosidase, and N-acetyl-beta-D-glucosaminidase were studied in the tumor tissue from various stages of cervical carcinoma of the uterus. Carbohydrate components of glycoprotein were found to be markedly reduced, and the reduction was very much significant in hexosamine and sialic acid in the advanced stages. Lysosomal glycosidases exhibited a significant increase, and among them N-acetyl-beta-D-glucosaminidase exhibited a prominent increase, in the advanced stages of cervical carcinoma of the uterus.

Carbohydrates↗
PubMed1991

In vivo absorption of 14C-glucose and 14C-glycine by the rat intestine during ochratoxin A toxicosis.

Ochratoxin A was administered orally at a dose level of 6 mg/kg/day for eight weeks to rats. Studies on the intestinal cellular macromolecules, activities of membrane bound enzymes and in vivo absorption of 14C-glucose and 14C-glycine exhibited significant alterations. The observed reduction in the absorption of these nutrients during ochratoxin A toxicosis is corroborated by the changes observed in the levels of cellular macromolecules and the activity of membrane bound enzymes which are involved in the transport system.

Adenosine Triphosphatases↗
PubMed1990

Synthesis, biological profile, and quantitative structure-activity relationship of a series of novel 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors.

A series of 9,9-bis(4-fluorophenyl)-3,5-dihydroxy-8-(alkyltetrazol-5-yl)- 6,8-nonadienoic acid derivatives 1 were synthesized and found to inhibit competitively the enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. The analogues having 1N-methyltetrazol-5-yl attached to the C8-position (3a, 4a, R1 = R2 = F) are the most active in suppressing cholesterol biosynthesis in both in vitro and in vivo models: the IC50 for the chiral form of 3a is 19 nM, Ki = 4.3 x 10(-9)M when Km for HMG-CoA is 28 x 10(-6) M;1 the ED50 (oral) value corresponding to the lactone derivative (4a, BMY 22089) is approximately 0.1 mg/kg. Further, BMY 21950 is nearly 2 orders of magnitude more active in parenchymal heptaocytes, from which most of the serum cholesterol originates, than in other cell preparations (such as spleen, testes, ileum, adrenal, and ocular lens epithelial cells; Table III). This apparent tissue specificity may be highly beneficial since the blocking of cholesterol biosynthesis in other vital organs could eventually lead to undesirable side effects. In addition to the chemical synthesis and biological evaluation, a theoretical study aimed at relating the HMG-CoA reductase inhibitory potency to the three-dimensional structure of the inhibitors was undertaken. With a combination of molecular mapping and 3D-QSAR techniques, it was possible to determine a logical candidate for the conformation of the bound inhibitor and to quantitatively relate inhibitory potency to the shape and size of both the binding site and the C8-substituent.

Animals↗
PubMed1990

Extraction-spectrophotometric determination of hydrogen sulphide.

A sensitive spectrophotometric method for the determination of trace amounts of hydrogen sulphide (H2S) after fixing in a modified zinc acetate-disodium ethylenediaminetetraacetate-sodium hydroxide solution is described. The fixed H2S is stable for 3 d. The reaction of iodate with H2S in the presence of acid and an excess of chloride leads to the formation of ICI which is stabilised as ICI2-. The species formed reacts with 2',7'-dichlorofluorescein to form 2',7'-dichloro-4',5'-diiodofluorescein which is extracted into a mixture of 15% isoamyl acetate in isoamyl alcohol. The colour system obeys Beer's law in the range 0-2.5 micrograms of H2S. The coefficient of variation is 4.5% for ten determinations of 2.0 micrograms of H2S. The effect of interfering gases on the determination is discussed. The method was applied to the determination of residual amounts of H2S present in a laboratory fume cupboard and the results obtained were compared with those given by the widely used Methylene Blue method. The method can be used to determine down to 0.3 micrograms of H2S.

Air Pollutants↗
PubMed1988

Gallium-67 localization in herpetic skin lesion.

Previous cases of gallium localization in various cutaneous lesions have been reported, including sporotrichosis, acne vulgaris, sarcoid, lymphoma, and exfoliative erythroderma. This is a report of a case of gallium localization in cutaneous lesions of herpes zoster.

Abdomen↗