Search PubMed⌕ Search

Biomedical subjects

K Kannan

Publications and source records attributed to K Kannan.

At least 109 records · Page 6Linked to original sources
PubMed1997

Distribution of selected PCB congeners in the Babcock Street sewer district: a multimedia approach to identify PCB sources in combined sewer overflows (CSOs) discharging to the Buffalo River, New York.

To evaluate sources of PCBs in combined sewer overflows (CSOs) to the Buffalo River, New York, combined sewage, sanitary flow, atmospheric wet and dry depositions, and street dust samples were collected from the Babcock Street sewer district and analyzed. Total PCB concentrations (sum of the PCB congeners quantitated) in particulate and dissolved phases of sanitary flow were 101-269 ng g-1 dry weight and <0.2 ng L-1, respectively. PCBs in the atmospheric dry and wet deposition samples were close to the method detection limit (a few pg/cm2 day-1 and <0.2 ng L-1, respectively). Average concentrations of total PCBs were noticeable in both dissolved (64 ng/l-1) and particulate (907 ng g-1 dry weight) phases in CSOs. Total PCBs in aggregates of street dust samples were between 53 and 1,700 ng g-1 dry weight, with the highest concentrations at sites nearest an industrial area that was previously remediated for PCB contamination. PCB congeners 153, 138, 101, 118, and 180 contributed >50% of the total PCB load in street dust samples. PCB congener composition in the particulate phase of CSOs reflects the congener pattern of the street dusts. In this context, it can be suggested that the local contaminated street dusts are one of the potential sources of PCBs in CSOs, which is a source of PCBs to the Buffalo River.

Animals↗
PubMed1997

Rapid analytical tryptic mapping of a recombinant chimeric monoclonal antibody and method validation challenges.

A rapid and reproducible analytical tryptic mapping method was developed as an identity test for a recombinant chimeric monoclonal antibody for lot release testing. The unfolding, reduction, carboxymethylation, trypsin digestion, and reversed-phase (RP) HPLC steps were optimized to provide a reproducible method. The optimized method requires 30 min for unfolding the protein, 30 min for carboxymethylation, 4 h for digestion with TPCK-trypsin and 140 min for RPHPLC analysis. The total time required is less than 8 h compared to conventional procedures, which must be performed over several days. The optimized method was validated for its precision, recovery, specificity, and robustness. The precision of the method was determined by repeatability and intermediate precision experiments. Relative standard deviation (RSD) values were < or = 10% for the relative peak areas of marker peaks. The mean recovery of these marker peaks was 88.4%. The specificity was demonstrated by the unique tryptic mapping patterns obtained compared with several other monoclonal antibodies. Robustness was demonstrated by the relative insensitivity of the tryptic map to small deliberate changes in key method parameters. Excessive relative peak area variability observed for one peak (RSD 52%) was traced to adsorption to glass autosampler vials. This variability was substantially reduced (RSD 11%) by substituting polypropylene autosampler vials. The data demonstrate that this method may be applicable to a wide range of pharmaceutically relevant monoclonal antibodies.

Antibodies, Monoclonal↗
PubMed1997

Optimisation of immunoaffinity purification of Wuchereria bancrofti specific antibodies from human sera.

Immunoaffinity column using Setaria digitata antigens coupled to cyanogen bromide activated Sepharose 4B beads were developed to purify antibodies from sera of filarial patients. Chaotropic (KSCN) ion elution was more efficient for purifying specific antibodies from the column in comparison to ]c elution. Dot blot analysis indicated that purified antibodies showed a high degree of reactivity with cattle filarial antigen and recombinant filarial protein but not with bacterial proteins of E. coli suggesting that the antibodies are specific.

Animals↗
PubMed1996

Effect of elevated glucose concentrations on cellular lipid peroxidation and growth of cultured human kidney proximal tubule cells.

This study has examined whether elevated glucose can induce lipid peroxidation and contribute to the inhibition of cell growth in human kidney proximal tubule(HPT) cells. HPT cells were cultured in media containing glucose concentrations of 8 mM (control), 25 mM, and 50 mM. Lipid peroxidation was assessed by the thiobarbituric acid reactivity and cell growth was assessed by 3H-thymidine uptake. Results show decreased (59%, p < 0.01) growth of HPT cells cultured in 50 mM glucose. Cells cultured in 50 mM mannitol did not show any growth inhibition, suggesting that the decreased cell growth associated with glucose is not due to osmolarity changes. There was an increase (108%, p < 0.02) in lipid peroxidation in cells cultured with high levels of glucose (50 mM) compared with controls and cells cultured with 50 mM mannitol. To examine if membrane lipid peroxidation or malondialdehyde (MDA, an end product of lipid peroxidation) has any role in the inhibition of cell growth, we examined the effect of tertiary butylhydroperoxide (TBH, known to cause lipid peroxidation and generate MDA) on the growth of HPT cells. TBH decreased cell growth (49, 17 and 3% of controls at 0.1, 0.25, and 0.5 mumole TBH/ml medium). Similarly, a marked reduction in the growth was observed with exogenous MDA (72, 69 and 34% of controls at 0.1, 0.25, and 0.5 mumole MDA/ml medium). This suggests that elevated glucose can induce membrane lipid peroxidation and accumulation of MDA, which in turn can inhibit cellular growth and contribute to the altered structure and function of HPT cells in diabetes.

Cell Division↗
PubMed1996

Lysosome-associated membrane proteins h-LAMP1 (CD107a) and h-LAMP2 (CD107b) are activation-dependent cell surface glycoproteins in human peripheral blood mononuclear cells which mediate cell adhesion to vascular endothelium.

Lysosome-associated membrane proteins (LAMPs) are transmembrane lysosomal glycoproteins which are detectable at the cell surface of lymphocytes in patients with scleroderma and systemic lupus erythematosus. While these proteins have been shown to mediate adhesion of tumor cells to vascular endothelial selectins, the function of LAMPs expressed at the cell surface of peripheral blood lymphocytes has not been previously examined. In the present study, the role of lamp2 (CD107b) in lymphocyte adhesion to vascular endothelium and the factors which influence in vitro cell surface expression of both lamp1 (CD107a) and lamp2 (CD107b) are examined. Freshly isolated PBMCs and unstimulated PBMCs in the culture had low levels of cell surface lamp1 and lamp2 expression which were significantly increased following PHA stimulation (P < 0.0001). A dose-dependent response to PHA and the effect of varying concentrations of serum were defined. Kinetic analysis revealed that the majority of the increase in both lamp1 and lamp2 occurred within the first 2 hr of incubation and that a subset of PBMCs maintained expression for at least 96 hr. Incubation of cells with colchicine and cycloheximide modified the cell surface expression of these proteins. Interleukins 2, 4, 6, and 8 had only a modest effect on the degree of cell surface lamp1 and lamp2 expression, though they did significantly affect the distribution of expression among different subtypes of lymphoid cells. Under the conditions utilized in this study, cell surface LAMP expression was confined primarily to CD56+ cells and to CD3+ cells. Functional analysis utilizing a fluorescence-based adhesion assay revealed that cell surface lamp2 mediates adhesion of PBMCs to vascular endothelium, possibly by interacting with endothelial selectins. LAMPs likely contribute to the migration of activated leukocytes to sites of inflammation in vivo.

Adult↗
PubMed1996

Accumulation pattern of butyltin compounds in dolphin, tuna, and shark collected from Italian coastal waters.

Tributyltin (TBT) and its breakdown products, mono-(MBT) and dibutyltin (DBT) were determined in bottlenose dolphin (Tursiops truncatus), bluefin tuna (Thunnus thynnus thynnus) and blue shark (Prionace glauca) collected from the Italian coast of the Mediterranean Sea in 1992-1993. Concentrations of total butyltin (BTs) in the liver of dolphin (1,200-2,200 ng/g wet wt) were an order of magnitude higher than in the blubber (48-320 ng/g wet wt). TBT was the predominant butyltin species in the blubber while DBT accounted for an higher proportion in the liver of dolphins. Butyltin concentrations in bluefin tuna were lower than those in dolphins, with TBT highest in the muscle and DBT in the liver. Concentrations of BTs in blue sharks were lower than those in dolphin and tuna, with kidney having the highest concentrations. TBT was the predominant form of butyltin derivatives in all the tissues of shark. Accumulation of butyltin compounds in liver/kidney seems to be associated with the presence of proteins such as glutathione.

Adipose Tissue↗
PubMed1995

Isomer-specific analysis of polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) in red fox and human adipose tissue from central Italy.

The general exposure of humans and foxes to polychlorinated biphenyls (PCBs) and DDT in Italy was determined by analysis of adipose tissue samples collected from 1991-1992. sigma PCB concentrations varied between 1.0 and 2.6 micrograms/g (wet wt.). sigma DDT concentrations ranged from 1.6 to 5.0 micrograms/g (wet wt.). About thirty-five PCB congeners were identified in most samples. PCB congeners of IUPAC Nos. 138, 153, and 180 were the most abundant compounds, accounting for an average of 50% of the sigma PCBs in humans and 64% in foxes. Generally, higher chlorinated biphenyls and those with a 2,4,5-chlorine substitution in one ring and at least one substitution in the 4-position of the other ring were preferentially accumulated. Coplanar PCB congeners were detected at considerable concentrations and there is no sign of decline in their concentrations with respect to previously reported data. IUPAC Nos. 118, 156 and 126 were the main contributors to toxicity in humans and foxes. The significant contribution of mono-ortho congeners in humans and non-ortho congeners in foxes suggests that differences in metabolic potential may affect the PCB toxicity pattern.

Adipose Tissue↗
PubMed1995

Butyltins in muscle and liver of fish collected from certain Asian and Oceanian countries.

Concentrations of butyltin residues were determined in muscle tissue of fish collected from local markets and sea food shops in India, Bangladesh, Thailand, Indonesia, Vietnam, Taiwan, Australia, Papua New Guinea and the Solomon Islands. Contamination levels were determined in the Asia-Pacific region and human exposure was estimated. Similarly, corresponding liver samples of fish muscle collected in Australia, Papua New Guinea and the Solomon Islands were analyzed to obtain information on partitioning of butyltin compounds between muscle and liver tissues. Butyltin compounds were detected in most of the samples which suggested widespread contamination in Asia and Oceania. The concentrations of butyltin compounds were, on average, an order of magnitude higher in liver than in muscle. Residue concentration of Sigmabutyltin in liver was found to be correlated significantly (p < 0.02) with those in muscle. Intensive ship-scrapping activities, sewage disposal and antifouling paints are considered the major sources of butyltins in this region. Increased proportions of MBT over DBT and TBT in samples from most locations indicated degradation of TBT to MBT in fish tissues during storage at 4 degrees C in the dark over 1-2 years. The possibility that fish have been subject to increased exposure to MBT and that TBT degrades to MBT quite rapidly in tropical environments are also considered. Butyltin concentrations in fish from Asia and Oceania were lower than those reported for Japan, Canada and the USA. Although the number of samples analyzed from each country was small, it is tentatively suggested that intake of butyltins by humans via consumption of fish in these countries was < 25% of the tolerable daily intake of 250 ng kg bw(-1) day(-1). To our knowledge, this is the first study reporting on butyltin pollution in developing Asian countries.

Journal Article↗
PubMed1995

Quantitation of CD62, soluble CD62, and lysosome-associated membrane proteins 1 and 2 for evaluation of the quality of stored platelet concentrates.

BACKGROUND: Platelets become activated during storage, which results in secretion of granules, vesiculation of microparticles, secretion of protein, and a number of other biochemical and morphologic processes that decrease the utility of platelet concentrates stored for transfusion. STUDY DESIGN AND METHODS: To evaluate the quality of stored platelet concentrates, the cell surface expression of specific activation-dependent antigens (CD62 and lysosome-associated membrane proteins 1 and 2 [LAMP-1, LAMP-2]) on platelets stored in a hospital blood bank over a 7-day period was examined. Relative microparticle counts and the expression of CD62 by microparticles, as well as platelet concentrate supernatant levels of soluble CD62, were determined. RESULTS: The percentage of platelets expressing CD62 increased significantly from Day 1 to Day 5 (p < 0.05) of storage; the mean fluorescence values for CD62 did not. In contrast, the mean fluorescence values of LAMP-1 and LAMP-2 rose significantly (p < 0.01 and p < 0.05, respectively) between Days 1 and 5. Significant declines in CD62, LAMP-1, and LAMP-2 percent expression and mean fluorescence were seen on Day 6 of storage (p < 0.001). Microparticle numbers increased significantly during storage and correlated with levels of CD62 protein (free and membrane-bound) (r = 0.95 vs. Day 2, p < 0.05; r = 0.88 vs. Day 5, p < 0.05). CONCLUSION: Flow cytometric evaluations of the expression of cell surface CD62, LAMP-1, and LAMP-2 are complementary tests that, especially when used in conjunction with the quantitation of CD62 protein, provided a simple and effective means of evaluating the quality of platelet concentrates stored for transfusion.

Antigens, CD↗
PubMed1995

Cell surface expression of lysosome-associated membrane protein-2 (lamp2) and CD63 as markers of in vivo platelet activation in malignancy.

Platelets may become activated in vivo in a number of prethrombotic conditions including cancer. In the present study, cell surface expression of lysosome-associated membrane protein-2 (lamp2) and CD63 (lamp3) were examined by flow cytometry in 15 healthy volunteers and 5 patients with metastatic cancer to determine their utility as markers of in vivo platelet activation. Unstimulated platelets from controls had low levels of lamp2 expression, in contrast to cancer patients, who had significantly elevated levels (3.79 +/- 1.48% vs 33.9 +/- 5.6%). Upon stimulation with collagen, a greater than two-fold increase in the number of platelets expressing detectable levels of lamp2 was seen only among controls and not in cancer patients. Stimulation with collagen also resulted in a nearly two-fold increase in the proportion of platelets expressing CD63 in the control group, and a less than 1.5-fold increase in CD63 was seen in the patient group. The results suggest that cell surface lamp2 and CD63, like cell surface expression of GMP-140, may be good indicators of in vivo platelet activation and may be potentially useful in identifying patients with prethrombotic disorders.

Adenosine Diphosphate↗
PubMed1994

Persistent organochlorine residues in foodstuffs from Australia, Papua New Guinea and the Solomon Islands: contamination levels and human dietary exposure.

Concentrations of polychlorinated biphenyls (PCBs), DDT and its metabolites (DDTs), HCH isomers (HCHs), chlordane compounds (CHLs), aldrin, dieldrin, heptachlor, heptachlor epoxide and HCB were determined in a wide variety of foodstuffs collected from different locations in Australia, Papua New Guinea and the Solomon Islands. Elevated levels of PCBs, CHLs, DDTs and dieldrin were detected in most of the foodstuffs of animal origin. Fish samples collected near the coast of Sydney recorded noticeable concentrations of PCBs, CHLs and DDTs. PCB contamination was generally prominent in samples collected in urban areas, whereas organochlorine pesticides were distributed uniformly throughout Australia. The widespread usage of CHLs was evident from the composition of its compounds in various foods while HCHs and DDTs were found to have been used sporadically in space and time. For the most part, residue levels of organochlorines in foodstuffs were below the tolerance limits established by national and international health organizations. The exception was CHLs in some fish samples, which exceeded the maximum residue limits recommended by the National Health and Medical Research Council of the Australian government. Although the number of samples analysed in each class of foods is small for the purpose of estimating human dietary exposure, we tentatively conclude that the dietary intake of PCBs in Australia was higher than those observed in most developed and developing nations, whereas the intake of organochlorine pesticides was higher than in developed nations but lower than in developing countries. Meat products contributed to the higher dietary intakes of most of the organochlorines. The contamination pattern and the residual concentrations of organochlorines in foodstuffs of Papua New Guinea and the Solomon Islands resembled those observed in Australia.

Animals↗
PubMed1994

Mercury, lead, cadmium, manganese, copper, iron and zinc concentrations in poultry, rabbit and sheep from the northern part of Poland.

The concentrations of mercury, lead, cadmium, manganese, copper, iron and zinc have been determined in poultry, rabbit and sheep from the northern part of Poland between 1988 and 1991. The method of measurement was cold vapour flameless AAS for mercury and flame AAS for other trace metals. Rabbits contained somewhat higher concentrations of lead in liver and kidneys than other species examined and the same could be observed in the case of cadmium in organ meats of duck and geese with apparently higher contamination of the rabbit's kidneys. While for an essential trace metals the values obtained seem to be species/tissue specific and typical.

Animals↗
PubMed1994

Alteration in lymphocyte phenotype associated with administration of adjuvant levamisole and 5-fluorouracil.

Levamisole (LMS) and 5-fluorouracil (5FU) administered adjuvantly are effective in reducing the relapse rate following surgical resection of Duke's stage C colon carcinoma. It has been postulated that LMS acts to stimulate the immune system and that this is one mechanism through which this drug exerts its antitumor effects. In this study, peripheral blood mononuclear cells (PBMC) were analyzed in nine patients with surgically resected colon carcinoma prior to initiation of adjuvant LMS/5FU and at several subsequent times while patients were on therapy. Changes in lymphocyte phenotype and soluble interleukin-2 receptor (sIL-2R) between pre-study samples and samples obtained during adjuvant LMS/5FU were evaluated. Significant increases were seen in the proportion of PBMC expressing natural killer (NK) antigen CD56 (14.7 +/- 2.4% versus 18.1 +/- 2.6%; P < 0.05) and surface IL-2R (CD25; 0% versus 0.42 +/- 0.15%; P < 0.05), in sIL-2R (314 +/- 86 U/ml versus 736 +/- 173 U/ml; P < 0.05), and in the CD4:CD8 ratio (2.34 +/- 0.93 versus 3.47 +/- 1.23; P < 0.01). A significant decrease in the proportion of CD8+ PBMC (24.7 +/- 3.8% versus 18.8 +/- 2.6%; P < 0.01) and total CD8+ PBMC (537 +/- 118 versus 324 +/- 37; P < 0.01) was seen. The increase in CD56+ cells correlated with sIL2R levels (r = 0.46; P < 0.05). No changes were noted for CD3, CD4, CD5, CD14, CD16, CD19, CDw49a, or TCR delta. The greatest increase in CD56+ cells and the smallest reduction in CD8+ cells were seen in the subgroup of patients who remained disease-free following adjuvant chemotherapy. This study suggests that adjuvant LMS/5FU has significant stimulatory effects on the immune system, which correlate with patient outcome and may account at least in part for its clinical efficacy.

Antigens, CD↗
PubMed1994

Effect of high glucose on cellular proliferation and lipid peroxidation in cultured Vero cells.

Nephropathy is common among the diabetic population. However, the molecular mechanisms by which hyperglycemia can cause alteration in kidney structure and function is not known. In this study, we examined the effect of high glucose levels on cellular growth and membrane lipid peroxidation in Vero cells, an African green monkey kidney cell line. Cell growth was assessed by a tetrazolium salt reduction test (MTT); and lipid peroxidation was measured by thiobarbituric acid reactivity. Our results show that elevated levels of glucose (25, 50 and 100 mM) can cause up to 50% reduction in cell growth in cultured Vero cells as compared with controls (8 mM). Also, we observed a significant increase in the amount of oxidative damage in Vero cells cultured with elevated glucose concentrations. This study demonstrates that hyperglycemia can cause increased lipid peroxidation and affect the cellular proliferation in a monkey kidney cell line.

Animals↗