[Show abstract][Hide abstract] ABSTRACT: Fatty acids are known to play a key role in promoting the loss of insulin sensitivity causing insulin resistance and type 2 diabetes. However, underlying mechanism involved here is still unclear. Incubation of rat skeletal muscle cells with palmitate followed by I(125)- insulin binding to the plasma membrane receptor preparation demonstrated a two-fold decrease in receptor occupation. In searching the cause for this reduction, we found that palmitate inhibition of insulin receptor (IR) gene expression effecting reduced amount of IR protein in skeletal muscle cells. This was followed by the inhibition of insulin-stimulated IRbeta tyrosine phosphorylation that consequently resulted inhibition of insulin receptor substrate 1 (IRS 1) and IRS 1 associated phosphatidylinositol-3 kinase (PI3 Kinase), phosphoinositide dependent kinase-1 (PDK 1) phosphorylation. PDK 1 dependent phosphorylation of PKCzeta and Akt/PKB were also inhibited by palmitate. Surprisingly, although PKCepsilon phosphorylation is PDK1 dependent, palmitate effected its constitutive phosphorylation independent of PDK1. Time kinetics study showed translocation of palmitate induced phosphorylated PKCepsilon from cell membrane to nuclear region and its possible association with the inhibition of IR gene transcription. Our study suggests one of the pathways through which fatty acid can induce insulin resistance in skeletal muscle cell.
Full-text · Article · Feb 2005 · Cellular Physiology and Biochemistry
[Show abstract][Hide abstract] ABSTRACT: One hundred forty-three patients, 72 males and 71 females, with extrapulmonary tuberculosis were aspirated and subjected to cytological (Ziehl-Neelsen stain) examination and culture in Lowenstein-Jensen media. Routine haematological examination and Mantoux test were done in all the cases, x-ray chest in 112, skeletal x-ray in 3 relevant cases and sputum was examined for AFB in 16 cases where pulmonary tuberculosis was associated/suspected with extrapulmonary tuberculosis. HIV status was evaluated in 51 cases and 9 (7.64%) were seropositive. FNA cytology in 102 cases (71.3%) had caseating epithelioid granulomas while smear for AFB was positive in 57 cases (39.8%). Both culture and smear were positive in 29 (20.2%) cases. Combining both smear and culture yielded positive results in 47.5% cases. It was observed that AFB positivity was higher in untreated patients and with HIV positive cases. Further more, the triad of FNAC, AFB smear and culture were cheaper, foolproof and confirmatory than costlier tests like TB IgG, IgM, RTPCR and BACTEC.
No preview · Article · Nov 2003 · Journal of the Indian Medical Association
[Show abstract][Hide abstract] ABSTRACT: The pancreatic beta-cell is the only cell in animals that expresses the insulin gene and secretes insulin protein. We have found copious release of immunoreactive and bioactive insulin into the medium from the primary culture of carp adipocytes. Glucose augmented this release to more than 2-fold, and glucose transporter, Glut2, was detected in these cells. These all reflect characteristics of a pancreatic beta-cell. The expression of the adipocyte-specific flotillin gene, the presence of peroxisomal proliferator-activated receptor gamma and Glut4, and the colocalization of insulin and leptin confirmed the identity of these cells as adipocytes. Purified carp adipocyte insulin (AdpInsl) comigrated with porcine and bovine insulin in SDS-PAGE, indicating the similarity of their molecular sizes (5.5 kDa). AdpInsl strongly reduced hyperglycemia in streptozotocin-induced diabetic rats. It also stimulated significantly higher glucose uptake in carp and hamster adipocytes than porcine insulin. Adipocyte RNA hybridized with rat and zebrafish insulin cDNA showing the expression of the insulin gene in this cell. Using oligonucleotide primers designed on the basis of conserved insulin domain, AdpInsl cDNA was reverse transcribed, cloned, and sequenced. The deduced amino acid sequence of AdpInsl A and B chain exhibited 98% homology with zebrafish and more than 70% homology with human, porcine, and murine insulin. To understand the structure-function relationship between AdpInsl and mammalian beta-cell insulin, we have analyzed the amino acid sequences and three-dimensional structure of AdpInsl. In the critical determinant segment for receptor binding, AdpInsl has His at the A8 position instead of Thr in human and porcine insulin, and this attributed greater biological activity to AdpInsl. Our results show that carp adipocyte is a unique cell. As an insulin target cell it can express the insulin gene and secrete highly active insulin protein; thus, it may serve as a natural alternative to pancreatic beta-cell insulin.