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Biomedical subjects

N Nath

Publications and source records attributed to N Nath.

At least 73 records · Page 4Linked to original sources
PubMed1984

Action of vitamin P like compounds on lysosomal fragility in hypercholesterolemia: implication of ascorbic acid and its metabolites.

Possible mechanisms responsible for hepatic lysosomal fragility in hypercholesterolemic rats have been investigated. It was found that certain factor(s) present in the intracellular environment of liver were required for the release of lysosomal enzymes. Elevated hepatic dehydroascorbic acid content in hypercholesterolemic rats is thought to render the lysosomes fragile in this pathological state, since this compound was found to labilise the lysosomes in vitro. Quercetin and hesperidin were found to be responsible for lysosomal stability, probably by reducing the content of dehydroascorbic acid to a normal level in the hypercholesterolemic condition.

Animals↗
PubMed1984

Ascorbic acid in thyroidectomized rats. II) Ascorbic acid status of the storage tissues and hepatic biosynthesis of glucuronic acid.

Depletion of ascorbic acid from adrenals, brain and epididymis along with loss in weight were noticed in the state of thyroidectomy. This decrease appears to be due to an effect of thyroidectomy on the membrane integrity since the membrane bound sialic acid was found to be significantly lowered in these tissues as a consequence of the elevated activity of sialidase. Thyroidectomy was also found to cause an adverse effect on the activities of hepatic UDP-glucuronyl transferase and beta-glucuronidase with no alteration in UDP-glucose dehydrogenase.

Adrenal Glands↗
PubMed1983

Unrelatedness of factor VIII-derived non-A/non-B hepatitis and hepatitis B virus.

A DNA hybridization assay was used to detect hepatitis B virus (HBV)-specific DNA sequences in extracted sera obtained from chimpanzees infected with HBV, hepatitis A virus (HAV), and a factor VIII-derived non-A/non-B (NANB) agent. The results did not reveal any HBV-DNA homology with sera obtained from animals infected with HAV or factor VIII-derived NANB. Sera obtained from two HBV-infected chimpanzees demonstrated that HBV-specific DNA could be detected during the acute phase of the disease. In addition, an HBV-specific DNA-dependent DNA polymerase assay did not demonstrate any statistically significant activity in 12 of 12 NANB acute-phase specimens or in 6 of 6 NANB chronic-phase specimens. These results suggest that the factor VIII-derived NANB agent is unrelated to HBV.

Animals↗
PubMed1983

Effect of fatty acid supplementation on the lipid composition of Mycobacterium smegmatis ATCC 607, grown at 27 degrees and 37 degrees C.

Mycobacterium smegmatis ATCC 607 was grown at 27 and 37 degrees C, with and without exogenous unsaturated fatty acids, viz. elaidic, oleic and palmitoleic acids, added to the growth medium. The total lipid content of M. smegmatis ATCC 607 was lower at 27 degrees C, and with added oleic acid, when compared with the controls, but higher in presence of palmitoleic acid. At 37 degrees C no significant differences were noted in the total lipid content. In general, the total lipid content was lower with all of the fatty acid supplementations at both 27 and 37 degrees C. The phosphatidylethanolamine content was slightly higher at 27 degrees C in the presence of elaidic or palmitoleic acid, but was markedly lower with oleic acid supplementation at 37 degrees C. The cardiolipin content was lower in the presence of any of the fatty acids at 27 degrees C, and higher in the medium supplemented with elaidic or oleic acid at 37 degrees C. The unsaturated to saturated fatty acids ratio was higher with palmitoleic acid supplementation at 27 degrees C, but remained unchanged in cells grown at 37 degrees C. The modifications in mycobacterial lipids are a reflection of the organism's ability to adapt to changing growth conditions.

Culture Media↗
PubMed1983

Hepatitis-associated markers in the American Red Cross blood donor population. V. Prevalence of antibodies to core antigen in three blood services regions.

A total of 20,643 samples of blood donated to three American Red Cross Blood Service regions were tested for antibodies to hepatitis B core antigen (anti-HBc) in order to evaluate and understand its significance and implications. All 20,643 samples were non-reactive for hepatitis B surface antigen (HBsAg) when screened at the regions. Overall, 2.2% of all samples were found to have anti-HBc, and a total of 16 had anti-HBc in the absence of antibodies to surface antigen (anti-HBs) activity. 1 of the 16 samples with anti-HBc in the absence of anti-HBs was found to have HBsAg when tested by a sensitive procedural modification of the Austria II test. Samples with low levels of anti-HBc activity were significantly more likely to be negative for anti-HBs.

Antibodies, Viral↗
PubMed1983

Action of vitamin P like compounds on lysosomal status in hypercholesterolemic rats.

Vitamin P like compounds such as quercetin and hesperidin administered at a dose of 50 mg/Kg/day along with a hypercholesterolemic diet for three weeks significantly restored the elevated cholesterol/phospholipid ratio in rats. Both these flavonoids exerted in vivo a stabilising effect on lysosomes in rat liver which had been rendered fragile in hypercholesterolemic condition. Moreover, these compounds also possessed the stabilisation effect on lysosomes in vitro. The stabilisation effect exerted on lysosomes was found to be due to the retarded release of lysosomal acid hydrolases and not to enzyme inhibition. Such stabilisation of the lysosomes may have a beneficial role in partial amelioration of hypercholesterolemic conditions.

Animals↗
PubMed1982

Structure of hepatitis B surface antigen. Correlation of subtype with amino acid sequence and location of the carbohydrate moiety.

Hepatitis B surface antigens (HBsAg) of both the adw and ayw subtypes have been purified from four different sources. These antigens have been compared by comparison of the products of tryptic hydrolysis performed under conditions which do not disrupt the overall particle morphology of HBsAg. The resultant peptides were compared by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and high performance liquid chromatography followed by amino acid analysis and Edman degradation of the isolated peptides. The same techniques were also applied to HBsAg which had been labeled with tritium in the carbohydrate moiety of the glycoprotein gp-30. These studies demonstrate that residues 122-150 of the protein p-25 and glycoprotein gp-30 occupy an exposed region of the HBsAg lipoprotein particle and contain the major attachment site for carbohydrate in the case of gp-30. The two subtypes were found to differ at two specific positions in this region, suggesting that this is an antigenically important area of the protein.

Amino Acid Sequence↗
PubMed1982

Inactivation of DNA-polymerase associated with hepatitis B virus.

The effects of heat, sodium hypochlorite, diethyl ether, and ethyl alcohol on the activity of DNA polymerase (DNA-P) associated with hepatitis B virsus (HBV) in serum were evaluated. The response of DNA-P to heating at 60 degrees C for 15, 30, 45, 60, 90, 120, 180, and 240 minutes was studied and the data suggested that there may be two types of DNA-P. The majority of DNA-P was type 'a', and it showed a one log reduction (D60) at 60 degrees C in 36 minutes, while the remaining activity was type 'b' that showed a one log reduction (D60) in 340 minutes. Treatment of DNA-P with sodium hypochlorite at concentrations of 250 and 500 parts per million (ppm) of available chlorine resulted in a 20 to 25% reduction in DNA-P activity within one minute. Complete loss in detectable DNA-P activity occurred within one minute when available Cl- was 2500 ppm or greater. Various concentrations of ethyl alcohol (ranging from 10 to 70%) caused gradually increasing inactivation of DNA-P activity in ten minutes at 4 degrees C. Ninety percent inactivation occurred with 60% alcohol. Overnight treatment of DNA-P-reactive material with diethyl ether at 4 degrees C led to loss of detectable activity. A reduction in the titer of HBsAg was found following treatment with alcohol or ether. The possible use of DNA-P assay as an indicator of the rate of inactivation of HBV is proposed.

DNA-Directed DNA Polymerase↗
PubMed1982

Hepatitis-associated markers in the American Red Cross volunteer blood donor population. IV. A comparison of HBV-associated serologic markers in HBsAg-positive first-time and repeat blood donors.

The present study was undertaken to determine whether there were any differences in the distribution of hepatitis B virus-(HBV) associated serologic markers among hepatitis B surface antigen-(HBsAg) positive first-time and repeat blood donors. The markers examined in samples from 412 newly identified HBsAg-positive donors (254 first-time and 158 repeat) included HBsAg titer and subtype, HBeAg/anti-HBe, and anti-HBc. Repeat donors were more frequently HBeAg-positive (25.9%) than were first-time donors (17.7%). Anti-HBc and anti-HBe were observed more often among first-time (99.6 and 76%) than repeat (91.8 and 60.8%) donors. No differences were found in the mean HBsAg titer nor in the subtype distribution in the two populations. The frequency of HBeAg positivity and the mean HBsAg titer in blood were significantly lower among first-time donors aged 30 or older as compared to those younger than 30. Such age-related tendencies did not occur among the repeat donors. The profiles of HBV makers suggest that the HBsAg-positive first-time donor group consists predominantly of long-term HBsAg carriers who may have acquired HBV at an early age, while the HBsAg-positive repeat donors have newly acquired infections.

Adolescent↗
PubMed1982

Proficiency in testing for hepatitis B surface antigen: experience with Ausria II.

Eight hepatitis B surface antigen (HBsAg) proficiency panels were tested using a radioimmunoassay (RIA) test kit during 1978 and 1979 by routine processing laboratories within the 57 American Red Cross Blood Services Regions. The test results were analyzed and it was found that lot-to-lot variability in the reagents may result in a measurable loss of sensitivity of the test leading to an increased error rate. On the basis of these studies, it is recommended that the positive to negative (P/N) ratio for validation of the test be raised to at least 25.

Analysis of Variance↗
PubMed1981

Pharmacokinetic study of chloramphenicol in patients with liver disease.

The pharmacokinetics of intravenous chloramphenicol has been studied in 42 patients with liver disease and in 8 controls. The half-life of chloramphenicol (t 1/2) was increased in the various liver disorders, the metabolic clearance rate (MCR) and apparent volume of distribution (Vd) were decreased and the area under the time - concentrations curve (AUC) showed an increase. The t 1/2 of chloramphenicol showed a significant correlation with serum albumin and prothrombin time index.

Acute Disease↗
PubMed1981

A modified technique for the detection of hepatitis B virus-specific DNA polymerase.

A modified and improved technique for the detection of hepatitis B virus-specific DNA polymerase activity is described. DNA polymerase is released from Dane particles by mixing samples with the detergent Nonidet P-40 and beta-mercaptoethanol. After incubation of pretreated samples with a reaction mixture containing tritiated thymidine-methyl-5'-triphosphate (3H-TTP), DNA is precipitated onto a trichloroacetic acid (TCA)-treated paper. Unincorporated 3H-TTP is then chromatographically eluted with a 5% TCA solution and precipitated counts are determined. A sample is considered positive for DNA polymerase if the incorporated counts are significantly higher than the counts of a group of negative control samples. The modifications include pretreatment of the paper with TCA, chromatographic elution of unincorporated 3H-TTP with TCA solution, prefiltration of the sample through bacteriological filters, and use of sound statistical methods for evaluation of data. These changes have led to a highly reproducible, reliable and sensitive technique. The coefficient of variation of negative control samples from various test runs was in the range of 2.7-8.5%. A linear relationship between incorporated counts and DNA polymerase concentration was shown. A total of 419 serum samples from asymptomatic HBsAg-carrying blood donors were tested. Twenty-three (5.5%) of these were found to contain detectable DNA polymerase activity. All 23 samples also contained HBeAg.

Chemical Precipitation↗