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Biomedical subjects

K Kannan

Publications and source records attributed to K Kannan.

At least 127 records · Page 7Linked to original sources
PubMed1993

Isomer-specific analysis and toxic evaluation of polychlorinated biphenyls in striped dolphins affected by an epizootic in the western Mediterranean sea.

Isomer-specific concentrations of polychlorinated biphenyls (PCBs) including planar, mono- and di-ortho congeners and concentrations of DDT were determined in striped dolphins affected by a morbillivirus epizootic in the western Mediterranean in 1990. Extremely high concentrations of PCBs ranging from 94 to 670 micrograms/g (wet wt) were detected in the blubber. Similarly, DDT concentrations were high, between 22 and 230 micrograms/g (wet wt). The concentrations of three non-ortho coplanar PCBs were 43 (3,3',4,4'-T4CB), 6.8 (3,3',4,4',5-P5CB), and 7.8 (3,3',4,4',5,5'-H6CB) ng/g (wet wt), respectively, the highest residue levels reported to date. The estimated 2,3,7,8-TCDD toxic equivalents of non-, mono- and di-ortho PCB congeners in striped dolphins were several times higher than those observed for other marine mammals and humans. Mono-ortho congeners contributed greater 2,3,7,8-TCDD toxic equivalents than non-ortho members. The higher ratio of 3,3',4,4',5,5'-H6CB/3,3',4,4',5-P5CB (IUPAC 169/126) suggested a strong induction of mixed function oxidase enzymes and highlighted the possibility of using this ratio as an index for risk assessment of PCB contamination in marine mammals. Elevated concentrations of PCBs may have played a role in the immune depression in striped dolphins, ultimately leading to the development of morbillivirus disease.

Adipose Tissue↗
PubMed1993

Polychlorinated biphenyl and organochlorine insecticide residues in human adipose tissue in Poland.

Concentrations of PCBs (polychlorinated biphenyls) and organochlorine insecticides such as DDT, HCHs (hexachlorocyclohexanes), HCB (hexachlorobenzene) and chlordanes were determined in human adipose fat from the provinces of Skierniewice and Gdańsk in Poland collected during 1979 and 1990, respectively. The mean levels (microg g(-1) lipid weight basis) in Skierniewice and Gdańsk were found to be 1.2+/-0.44 and 1.5+/-1.3 for PCBs, 25+/-16 and 15+/-13 for DDT, 0.53+/-0.17 and 0.25+/-0.09 for HCHs, 0.36+/-0.22 and 0.26+/-0.23 for HCB, and 0.11+/-0.08 and 0.07+/-0.04 for chlordanes, respectively. Very high concentrations of DDT were detected, with the maximum value as high as 52 microg g(-1) lipid weight in Skierniewice and 47 microg g(-1) lipid weight in Gdańsk. PCB residues contained in the human fat from Polish cadavers are comparable to those of the levels reported for industrialized nations. It is appraised from the levels of DDT and PCBs in Poles' fat that the Polish environment is still experiencing both types of contamination, arising from agricultural and industrial activities. Contamination of humans by other organochlorine insecticides was relatively lower.

Journal Article↗
PubMed1993

Demonstration of a ubiquitin binding site on murine haemopoietic progenitor cells: implication of ubiquitin in homing and adhesion.

Investigations into the nature of the molecular interactions mediating the recognition of the haemopoietic progenitor cells by the haemopoietic stroma, indicate that ubiquitin mediates the binding between murine haemopoietic progenitors and the haemopoietic stroma. The adhesion of haemopoietic progenitors to anti-ubiquitin antibody treated bone marrow stroma cultures, shows inhibition of binding by approximately 78%. Affinity purification of the 1% Triton X-100 soluble stromal membrane fraction, on anti-ubiquitin-sepharose revealed a ubiquitinated 55 kD subunit. Progenitor cells treated with ubiquitin show approximately 58% inhibition in their ability to home into spleen, indicating the direct involvement of ubiquitin in homing. Histochemical staining of bone marrow cells using ubiquitin as a probe further delineates a population of cells possessing specific binding sites for ubiquitin. We demonstrate here the presence of a ubiquitin binding site on the haemopoietic progenitor cells, which may play a major role in the targeting of such progenitors to their 'niche' within the haemopoietic tissue. Such ubiquitin-mediated recognition may thus constitute a common molecular mechanism for homing and adhesion to both bone marrow and spleen, and may be implicated in the homing of more primitive, less differentiated haemopoietic progenitors. The results also indicate that the homing of haemopoietic progenitors within the haemopoietic micro-environment may be mediated by both a ubiquitin dependent and another ubiquitin independent mechanism.

Animals↗
PubMed1992

Residue pattern and dietary intake of persistent organochlorine compounds in foodstuffs from Vietnam.

Concentrations of polychlorobiphenyls (PCBs), hexachlorocyclohexane isomers (HCHs), DDT compounds (DDTs), hexachlorobenzene (HCB), aldrin, dieldrin, heptachlor and heptachlor epoxide were determined in foodstuffs collected from different locations in Vietnam. Elevated levels of PCBs, DDTs, HCHs, and aldrin and dieldrin were found in animal fat, butter, meat, and seafood. Caviar and butter samples imported from the Soviet Union contained considerably higher amounts of PCBs, HCHs and DDTs. The average daily intake of some organochlorines by Vietnamese people were higher than those observed in most of the developed nations. The dietary intake of DDTs was the highest among various chemicals studied. Interestingly, the daily dietary intake of PCBs was comparable to those in developed countries. Fish, shellfish, prawn, and crab were the primary route of DDTs to humans, whereas cereals and vegetables were the predominant sources of PCBs and HCHs.

Food Analysis↗
PubMed1992

Characteristic trend of persistent organochlorine contamination in wildlife from a tropical agricultural watershed, south India.

The residue levels of persistent organochlorines, such as HCH (BHC: 1,2,3,4,5,6-hexachlorocyclohexane) isomers, DDT [1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane] compounds, PCBs (polychlorobiphenyls) and HCB (hexachlorobenzene), were measured in wildlife. The wildlife were sampled from terrestrial and aquatic habitats in and around the agricultural watershed of Parangipettai, South India. On the basis of overall concentrations sigma HCH ranked first followed by sigma DDT, sigma PCB and HCB, reflecting the increasing usage of HCH in recent years in India. The residue levels of organochlorines in birds varied according to their feeding habits and showed the following pattern: inland piscivores and scavengers greater than coastal piscivores greater than insectivores greater than omnivores greater than granivores. High levels of HCH and DDT residues were recorded in Pond heron and Cattle egret which feed in the agricultural fields. Comparison of HCH concentrations in fish and birds in the study area to other locations was made to further understand the dynamics of contaminant accumulation in tropical wildlife. Regarding birds, a wide variation in residue levels could be seen among various countries, with tropical regions registering high levels. In contrast, the variation is not prominent in the case of fish. The residue levels in fish measured in the present study were generally comparable to values reported from other locations. This suggests that the bioavailability of contaminants to the aquatic fauna is less due to the smaller flux and shorter residence time of these chemicals in the tropics.

Agrochemicals↗
PubMed1992

Organochlorine pesticide and polychlorinated biphenyl residues in slaughtered and game animal fats from the northern part of Poland.

Pooled samples of the adipose fat of swine, cows, sheep, rabbit, ducks, geese, turkeys, wild boar, roe deer and stags collected from the northern part of Poland in 1987-88 were analysed for the presence of polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), hexachlorohexanes (HCHs), Dichlorodiphenyltrichloroethanes (DDTs), aldrin, dieldrin, heptachlor, heptachlor epoxide and chlordanes (CHLs). All the fats contained detectable, but low concentrations of organochlorine pesticides and PCBs. The mean PCB levels ranged from 9.2 to 47 micrograms/kg of which IUPAC nos. 138, 153, and 180 were dominating congeners in most of the samples. DDT concentrations were apparently lower in fat of the ruminants (45 to 84 micrograms/kg fat) while in rabbits, swine, turkeys and geese, it was from 79 to 140 micrograms/kg fat. Ducks and wild boar had the highest concentrations of 400 and 440 micrograms DDTs/kg fat, respectively. HCB was detected at concentrations ranging from 2.0 to 18 micrograms/kg fat. The total HCH concentration ranged between 15 and 77 micrograms/kg fat. Aldrin and heptachlor remained undetected while dieldrin was found only in some slaughtered species with a range of positive measurements up to 9.1 micrograms/kg fat. Similarly, heptachlor expoxide was traced up to 9.1 micrograms/kg fat and the residues of CHLs from 0.34 to 4.1 micrograms/kg fat.

Abattoirs↗
PubMed1992

Ubiquitin with a non-ATP-dependent slow intrinsic proteolytic activity: a mild and rapid purification procedure.

Ubiquitin has been purified to homogeneity, through a dialysis membrane having a NMW cutoff of 12 kDa, by taking advantage of its non-dialysable nature under these conditions. The dialysate was continuously recycled through a CM-52 cation exchange column at pH 4.5. The adsorbed fraction was eluted selectively at pH 7.2. Ubiquitin (25 mg) was obtained from 500 ml of packed RBCs. On SDS PAGE, ubiquitin showed varying mobility depending on the time of boiling in SDS. With 2 min of boiling, the molecular weight seemed to be 10.5 kDa, whereas 10 min of boiling resulted in a molecular weight of 8.5 kDa. Ubiquitin showed a slow intrinsic proteolytic activity against SDS-denatured beta-galactosidase in the absence of ATP. For the first 4 hr, there was no detectable degradation, but degradation was nearly complete after 8 hr. These data are not in agreement with those of Freid et al. [Proc. Natl Acad. Sci, USA, 84 (1987), 3685] who have reported a proteolytic activity comparable to that of other proteolytic enzymes.

Adenosine Triphosphate↗
PubMed1991

Organochlorine pesticide and polychlorinated biphenyl residues in foodstuffs from Bangkok, Thailand.

Raw foodstuffs collected from Bangkok, Thailand, were analysed for the presence of PCBs, DDTs, HCHs (BHCs). HCB, aldrin, dieldrin, heptachlor and heptachlor epoxide. Residues of PCBs and organochlorine pesticides were detected in all the samples analysed. Concentrations of PCBs did not reach the tolerance limit set forth by the US Food and Drug Administration (FDA). The concentrations of SigmaHCH were higher than those of SigmaDDT in all the farm products while the levels of SigmaDDT were greater in fishes including fish flakes and fishmeal. Meat samples recorded higher concentrations of SigmaDDT and dieldrin than SigmaHCH. Comparing the levels of organochlorines in foodstuffs from Bangkok, considerable levels of aldrin and dieldrin indicate the need for concern from the food safety point of view because of their much higher toxicity than DDT and other organochlorines. However, the levels did not exceed the Maximum Residue Limit (MRL) recommended by FAO/WHO. Food contamination by HCB, heptachlor and heptachlor epoxide is comparatively lower.

Journal Article↗
PubMed1988

Purification and characterisation of glucose (xylose) isomerase from Chainia sp. (NCL 82-5-1).

Glucose (xylose) isomerase is an important enzyme in high fructose syrup industry. The enzyme generally occurs intracellularly and is specific for both glucose and xylose. A rare actinomycete Chainia sp. (NCL 82-5-1) produces extracellular specific glucose and xylose isomerases and an intracellular glucose (xylose) isomerase. The intracellular enzyme is isolated by cell autolysis and purified by preparative polyacrylamide gel electrophoresis. Its properties are studied and compared with those of extracellular specific xylose isomerase. The intracellular enzyme has a molecular weight of 1,58,000 daltons with four equal subunits of 40,700 daltons. The N-terminal amino acid sequence analysis shows Arg at the N-terminal. Diethylpyrocarbonate inhibited the enzyme and the inhibition kinetics study shows the presence of at least 2 essential His residues. The amino acid analysis shows the absence of Cys and a high proportion of hydrophobic and acidic amino acids.

Actinomyces↗
PubMed1985

Effect of 2,5-hexanediol on immunocompetence of mice.

A preliminary study on immunotoxicologic evaluation of 2,5-hexanediol (one of the principal metabolites of n-hexane), involving multiple immunological parameters, was carried out in mice. Mice were exposed to 2,5-hexanediol at a 1/5 LD50 dose level for 7 days. Pathotoxicological changes such as marked reduction in absolute and relative lymphoid organ weights, histological abnormalities in thymus, spleen, and adrenal, and reduction in cellularity of lymphoid organs were found. Immune function tests such as delayed hypersensitivity reactions, plaque-forming cell assays, serum antibody titer against SRBC, and resistance to endotoxin shock were also markedly impaired. Results obtained in this study showed that 2,5-hexanediol causes impairment to immunocompetence in mice.

Administration, Oral↗
PubMed1985

Myxedema coma.

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Adult↗
PubMed1984

Subcutaneous kerosene toxicity in albino rats.

Biochemical, histopathological, and hematological parameters were studied in male Wistar rats after repeated subcutaneous administration of commercial kerosene (0.5 ml/kg body wt, 6 days a week) for a period of 35 days. At necropsy, treatment-related increases in the weights of liver, spleen, and peripheral lymph nodes were noted. Correspondingly, there was an increase in DNA, RNA, protein, and lipid contents of liver and spleen. Histopathological examination of liver, spleen, thymus, kidney, adrenal, and lymph nodes revealed treatment-related lesions. Similarly, biochemical indices studied in liver revealed an increase in alkaline phosphatase and a decrease in benzo[a]pyrene hydroxylase levels. Furthermore serum cholinesterase, carboxylesterase, and albumin levels were significantly diminished while serum alkaline phosphatase levels were found to be greatly enhanced. The findings might be related as the likely systemic effects in workers upon percutaneous kerosene exposure during work.

Air Pollutants, Occupational↗
PubMed1984

Comparison of tryptic peptide profiles of alcohol dehydrogenase from Drosophila melanogaster at different ages: a rapid procedure using high performance liquid chromatography.

Age-related changes in the primary structure of alcohol dehydrogenase (ADH) from three different strains (Adh-F, Adh-D and Adh-S) of Drosophila melanogaster have been investigated by tryptic peptide analysis. The procedure involves isolation of 14C-labelled ADH, immunoprecipitation and HPLC separation of tryptic peptides. This method is rapid, reproducible and sensitive. By using this procedure it is demonstrated that there are no significant differences between the ADH tryptic peptide profiles of young (10-day-old) and old (50-day-old) flies. The usefulness of this procedure for screening mutant and variant enzymes is discussed.

Aging↗