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Biomedical subjects

S Narayanan

Publications and source records attributed to S Narayanan.

At least 109 records · Page 6Linked to original sources
PubMed1990

Effect of educational intervention on defaecation habits in an Indian urban slum.

The defaecation habits of 172 adults before and after a cholera epidemic in New Delhi in 1988 were investigated. Intensive educational activities were undertaken during the epidemic. A community latrine facility was constructed in this area in February 1988. A greater proportion of females than males were found to be exclusively using the latrines at both rounds of the investigation. A statistically significant relationship with age was observed (P less than 0.001), while literacy was not found to exert a statistically significant effect. Difference in usage habits were more marked in the second round of the investigation. Cost and distance were the main reasons cited for non-utilization of latrines. 91.4% of respondents stated that they had faced some problem in using latrines. Most children were found to be defaecating in the open around the dwelling units at both rounds of the investigation.

Adult↗
PubMed1988

Potential inhibitors of S-adenosylmethionine-dependent methyltransferases. 11. Molecular dissections of neplanocin A as potential inhibitors of S-adenosylhomocysteine hydrolase.

A series of 9-(hydroxyalkenyl)purines (adenines and 3-deazaadenines), which are analogues of neplanocin A, were synthesized. The analogues were tested as inhibitors of bovine liver and murine L929 cell S-adenosyhomocysteine (AdoHcy) hydrolase (EC 3.3.1.1) and as inhibitors of vaccinia virus replication in murine L929 cells. Compounds 1b, 2a, 2b, 4a, 4b, 7, 9a, and 9b showed the best inhibitory effects toward bovine liver AdoHcy hydrolase, with compound 4b being the most potent. The compounds that were shown to be the most potent inhibitors of the bovine liver AdoHcy hydrolase all contained an allylic hydroxyl group in the cis position to the adenine or the 3-deazaadenine rings. It was concluded that the cis arrangement of the allylic hydroxyl groups in these acyclic compounds represented the minimum structural requirement of the trihydroxycyclopentenyl ring of neplanocin A to show inhibitory effects against AdoHcy hydrolase. The antiviral effects of these acyclic analogues were significantly less than neplanocin A; however, there appears to be a correlation between the antiviral activity and the inhibition of AdoHcy hydrolase for compounds 2a, 2b, 4a, 4b, and 7. Analogue 4b, which exhibited the best antiviral activity (IC50 = 70 microM) in this acyclic series, is substantially less potent than neplanocin A (IC50 = 0.08 microM) as an antiviral agent.

Adenine↗
PubMed1988

Proton magnetic relaxation studies in normal and cancerous breast tissues.

Proton magnetic resonance (PMR) relaxation times were measured for dissected malignant and normal tissue derived from breast cancer patients. Relaxation time measurements (T1, T2) were carried out at a RF frequency of 20 MHz and at a temperature of 27 degrees C with a Brucker PC 120 NMR Process analyser. The tissue types were confirmed by histopathological examination. In general T1 values were found to be longer for malignant tissues as compared to normal tissues which is in agreement with the earlier observations. The measured T2 values do not exhibit the malignant tissues above. The percentage of water content was also measured in both normal and malignant tissue and was found to be considerably larger in tumour tissue as compared to normal tissue. These results are discussed on the basis of two fraction fast exchange models of water molecules and confirm that PMR relaxation time measurement plays an important role in the differentiation of cancerous tissues from that of normal.

Breast↗
PubMed1985

Assessment of blood collection systems for the high performance liquid chromatography measurement of propranolol.

The effect of blood collection devices on the high performance liquid chromatography (HPLC) measurement of propranolol was assessed. Blood was collected from hypertensive patients treated with propranolol for at least 7 days. Two venipunctures (opposite arm technique) were performed on each patient using the reference (syringe/silanized, ethylene diamintetraacetate tubes) procedure and the Vacutainer Brand Tubes (lavender-, royal blue-, green-, and red-stoppered) that were free of tris(2-butoxyethyl) phosphate. Propranolol concentrations were determined utilizing a published HPLC procedure. This study showed that in the four evacuated tubes, propranolol concentrations in serum or plasma were highly correlated to those of the reference procedure (correlation coefficients, 0.986 to 0.997; and slope, 0.912 to 1.013). Mean propranolol concentrations of the red-stoppered tube serum were lower (7.5%) than that of the reference syringe (0.01 less than p less than 0.05). Thus, lavender-, royal blue-, green-, and red-stoppered tubes would be acceptable for propranolol monitoring.

Blood Specimen Collection↗
PubMed1982

Simultaneous quantitation of quinidine, procainamide, and N-acetylprocainamide in serum by gas-liquid chromatography with a nitrogen-phosphorus selective detector.

We describe a single-run method for quantitating quinidine, procainamide, and N-acetylprocainamide, involving gas-liquid chromatography with a nitrogen-phosphorus selective detector. Within-run precision (CV) was 3% (x = 2 mg/L, n = 20), 6.9% (x = 4 mg/L, n = 10), and 1.5% (x = 8 mg/L, n = 8) for quinidine; 7.7% (x = 4 mg/L, n = 14), 1.6% (x = 8 mg/L, n = 16), and 2.3% (x = 12 mg/L, n = 12) for procainamide; and 6.3% (x = 5 mg/L, n = 6), 3.6% (x = 10 mg/L, n = 20), and 4.0% (x = 20 mg/L, n = 10) for N-acetylprocainamide.l Between-run precision was 3.0%(x = 2 mg/L, n = 20), 7.0% (x = 4 mg/L, n = 9), and 2.8% (x = 8 mg/L, n = 9) for quinidine; 4.7% (x = 4 mg/L, n = 10). 3.3% (x = 8 mg/L, n = 20), and 1.9% (x = 12 mg/L, n = 10) for procainamide; and 9.3% (x = 5 mg/L, n = 6), 4.3% (x = 10 mg/L, n = 20), and 3.8% (x = 20 mg/L, n = 10) for N-acetylprocainamide. Tube stoppers that contain a rubber plasticizer interfere with the technique. Clinical application and correlation with drug concentrations by this technique are discussed.

Acecainide↗
PubMed1980

gamma-Chloronorvaline, a leucine analog from Streptomyces.

gamma-Chloronorvaline (AL-719) and gamma-hydroxynorvalinelactone (AL-719Y) were isolated from the culture broth of Streptomyces griseosporeus AL-719. Physico-chemical studies led to the structure elucidation of AL-719 and 719Y, with there respective configurations of (2S, 4S) and (2S, 4R). AL-719 shows antibacterial activity on a synthetic agar, especially against Pseudomonas aeruginosa, which was reversed by L-leucine. The producing strain AL-719 was characterized.

Anti-Bacterial Agents↗
PubMed1980

Creatinine: a review.

Measurement of creatinine has many applications. We review the determination of urinary creatinine as a valid index of completeness of 24-h urine collection, the clinical utility of the determination of creatinine clearance ratios, and measurement of the ratio of the clearance of specific analytes, such as amylase, to the ratio of clearance of creatinine. The chemistry and variables that affect the Jaffé reaction are reviewed, and attempts at improvement of specificity are discussed. We also review and assess techniques other than the Jaffé reaction for measurement of creatinine.

Amylases↗
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↗