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Biomedical subjects

S Narayanan

Publications and source records attributed to S Narayanan.

6 recordsLinked to original sources
PubMed1979

Lipoprotein-X.

Lipoprotein-X is an abnormal lipoprotein that appears in the sera of patients with obstructive jaundice, and thus is a sensitive indicator of cholestasis. In patients with familial plasma lecithin, Cholesterol acyltransferase (LCAT) deficiency, there is an inverse relationship between plasma Lp-X levels and LCAT activity. Ultracentrifugation procedures utilized for isolation of Lp-X have shown that it is associated with the low density lipoprotein fraction. Lp-X can be visualized by electrophoresis on either Agar or Agarose. The purity of Lp-X preparations has been documented by immunochemical procedures. The availability of highly purified antisera to Lp-X has served as a basis of one of the assay procedures for this lipoprotein. It's chemical composition has been established. Phospholipids and unesterified cholesterol constitute the bulk of the Lp-X molecule. Electron microscopic studies have demonstrated that Lp-X is a spherical particle which has strong aggregating properties. Membrane bound enzymes have been shown to aggregate with Lp-X. The fact that bile lipoprotein can be converted to Lp-X by the addition of albumin and that Lp-X can be converted to bile lipoprotein by the addition of bile salts offers a possible explanation for the origins of Lp-X. Phospholipases of plasma might play a role in the catabolism of Lp-X. The value and limitations of Lp-X determinations will also be addressed in this review.

Alkaline Phosphatase↗
PubMed1977

Spectrum of immune response abnormalities in different clinical forms of tuberculosis.

In an attempt to explain the reasons for the development of different clinical forms of tuberculosis in different persons, their immunologic status was compared to their clinical patterns. The spectrum of immunologic abnormalities correlated with the clinical forms. Also, an inverse relationship between cell-mediated and humoral immune responses was observed. Immunologic abnormalities reverted to normal concomitant with clinical improvement on chemotherapy, suggesting that the abnormalities were the result of the illness rather than its cause. Malnutrition could have been the underlying factor for the immunologic deficiencies seen in some patients.

Antibodies, Bacterial↗
PubMed1976

Immobilized glucose oxidase used in the continuous-flow determination of serum glucose.

We used a tubular glucose-oxidase wall reactor in the "AutoAnalyzer II" continuous-flow analytical system to determine glucose in blood serum. Sensitivity was high and wash characteristics were satisfactory with use of a 30-cm tube containing immobilized glucose oxidase. Results compared favorably with those of the conventional free-enzyme method. More than 25000 such assays can be performed with a single enzyme tube, which also shows long-term storage stability. Because of the steady-state chemistry 60 samples can be analyzed per hour. The linearity of the method is excellent and sample interaction from 5.0 to 1.0 g/liter is less than 5%. Results correlate well (greater than 0.993) with those obtained with both the neocuproine method used in the "SMA 12/60" multichannel analytical system and the free glucose oxidase method used in the AutoAnalyzer.

Autoanalysis↗
PubMedDate not supplied

Overview of principles and current uses of DNA probes in clinical and laboratory medicine.

Fundamental considerations of deoxyribonucleic acid (DNA) probe hybridization reaction including concept of stringency is reviewed. Restriction fragment length polymorphism (RFLP) and its detection using DNA probes are discussed together with the importance of RFLP in genetic linkage analysis. Methodological considerations, such as limitations in sample preparation and improvements effected in techniques, cloning DNA, and labelling of DNA probes, are addressed. Principles of hybridization technology and blotting techniques are reviewed. Amplification of DNA by the polymerase chain reaction (PCR), labelling with PCR, detection of PCR products and separation procedures prior to use of PCR are discussed. Other amplification methods and in-situ hybridization (ISH) procedures are reviewed. Selected current applications of DNA probes in the area of infectious diseases, genetic diseases, HLA typing, paternity and forensic testing are briefly discussed. Emphasis is placed on the use of DNA probes in the area of oncology. Background on activation of proto oncogene, loss of tumor suppressor genes, chromosomal translocation, and chromosome analysis are provided for understanding DNA probe assays for ph1 positive leukemias and applications of Interphase cytogenetic technique in oncology. Finally, analytical strategies for detection of tumor suppressor genes are addressed.

DNA Probes↗