Biomedical subjects

G Kaur

Publications and source records attributed to G Kaur.

At least 73 records · Page 4Linked to original sources

PubMed1997

Chromosome 3p24-26 and 3p22-12 loss in human prostatic adenocarcinoma.

Identification of loss of heterozygosity on specific genetic loci is crucial for understanding the pathogenesis of prostate cancer at the molecular level. This is especially important because the deleted regions may contain putative tumor suppressor genes. Chromosome 3p loss appears to be frequently associated with various epithelial cancers. To our knowledge, there is no report on loss of heterozygosity (LOH) of chromosome 3 in human prostate cancer. The present study was designed to investigate the LOH on chromosome 3p in microdissected samples of delineated regions of normal and invasive carcinoma areas of prostatic epithelium from the same tumor sections. For this purpose, DNA was extracted from microdissected normal and tumor cells of 38 prostate cancers, amplified by PCR and analyzed for LOH on chromosome 3p using 6 different polymorphic DNA markers (D3S1560, THRB, D3S647, D3S1298, D3S1228 and D3S1296). Our results suggest that LOH was identified in 34 of 38 cases (89%) with at least one marker. Twelve of 30 informative cases showed LOH at D3S1560; 18 of 22 informative cases showed loss at THRB; 20 of 38 informative cases showed deletion at D3S647; 16 of 38 informative cases showed loss at D3S1298; 12 of 34 informative cases showed LOH at D3S1228; and 6 of 34 informative cases showed LOH at D3S1296 regions. Our results suggest that the LOH is on the 3p24-26 and 3p22-12 regions of the short arm of chromosome 3, indicating 2 discrete areas of deletion on chromosome 3p. The deletion at 3p24-26 and 3p22-12 was not related to the stage or grade of the tumor.

Adenocarcinoma↗

PubMed1997

Genetic variations at the T cell receptor gamma locus in circulating peripheral blood mononuclear cells of clinically categorised leprosy patients.

The allelic polymorphisms at exon 3 and exon 2 of the T cell receptor (TCR) C gamma 2 (TRGC2) gene, generating 18-kb and 5.4-kb HindIII fragments, respectively, were found to be more frequent in multibacillary leprosy patients than in the controls (P < 0.005 and P < 0.001, respectively) when screened with the IDP2.11 probe. The frequencies of heterozygotes for the 18-kb allele and homozygotes for the 5.4-kb allele were found to be significantly higher in the multibacillary patients than in the controls (P < 0.001). Interestingly, the 8.0-kb allele, originating from the triplication of exon 2 of C gamma 2, was observed exclusively in the paucibacillary leprosy patients. Further, when DNA samples were screened with the pH60 probe for the HindIII RFLP at the TCR J gamma 2 (TRGJ2) gene segment, the 2.1-kb allele was again more prevalent in leprosy patients with the multibacillary form of the disease than in the paucibacillary patients and the controls (P < 0.025). The frequency of homozygotes for the 2.1-kb allele was also significantly higher in the multibacillary patients than in the paucibacillary patients (P < 0.010) and the controls (P < 0.025). A significant difference was observed in the frequencies of detectable rearrangements involving the V gamma 7/8 and V gamma 9 gene segments at the gamma locus between circulating peripheral blood mononuclear cells of the multibacillary leprosy patients and the controls. These rearrangements were detected less frequently in the multibacillary patients (P < 0.001 for V gamma 7/8 and P < 0.005 for V gamma 9).

Alleles↗

PubMed1997

Association of polymorphism at COL3A and CTLA4 loci on chromosome 2q31-33 with the clinical phenotype and in-vitro CMI status in healthy and leprosy subjects: a preliminary study.

Two genetic loci, viz. COL3A and CTLA4, located within the chromosome 2q31-33 region in the vicinity of the proposed syntenic site of the mouse "Bcg" locus were genotyped by the polymerase chain reaction in leprosy patients and healthy individuals. All the subjects studied were assessed as in-vitro responders/non-responders to mycobacterial antigens. Simple sequence length polymorphism analysis revealed five (236 to 312 bp) and eight (84 to 120 bp) allelomorphs for COL3A and CTLA4, respectively. Our preliminary analysis showed a significant association between the 250-bp COL3A allelomorph in the homozygous condition and the multibacillary form of leprosy (P < 0.05: relative risk = 5.5). Another allelic (312 bp) variant of COL3A was significantly correlated with non-responsiveness to M. leprae antigens in vitro (P < 0.01). The 104-bp allelomorph of CTLA4 was not observed in any of the 25 cases of leprosy. This absence was statistically significant (P < 0.05) when compared with normal healthy controls and depicted a high relative risk (RR = 25.83). An additional observation of the predominance of a unique 84-bp CTLA4/CTLA4-like allelomorph was observed in the Indian subjects studied.

Abatacept↗

PubMed1997

Effect of experimental diabetes on monoamine oxidase activity from discrete areas of rat brain: relationship with diabetes associated reproductive failure.

The effect of alloxan-induced diabetes was studied on the activity of monoamine oxidase (MAO), the oxidative deaminating enzyme of monoamine neurotransmitters. MAO was assayed from discrete brain regions like medial preoptic area and median eminence--arcuate region of hypothalamus, septum, amygdala, thalamus, hippocampus, pons and medulla. In all these areas studied, the induction of diabetes resulted in significant increase in MAO activity at 3, 8, 15 and 28 day intervals, whereas, the treatment of diabetic rats with insulin led to recovery in the enzyme activity. Blood glucose levels increased significantly after induction of diabetes and the recovery was seen after insulin treatment. These data suggest the involvement of MAO in diabetes associated alterations in physiological and endocrinological disorders.

Animals↗

PubMed1997

GABA agonists and neurotransmitters metabolizing enzymes in steroid-primed OVX rats.

The effect of intraventricular (IVT) administration of GABAA receptor agonist muscimol and GABAB receptor agonist, baclofen was examined on the activity of acetylcholinesterase (AChE), monoamine oxidase (MAO) and Na+, K(+)-ATPase in discrete areas of brain from estrogen-progesterone primed ovariectomized rats. AChE enzyme activity was increased in two subcellular fractions (soluble and total particulate) studied, with statistically significant changes in cerebral hemispheres (CH), cerebellum (CB), thalamus (TH) and hypothalamus (HT), Na+, K(+)-ATPase enzyme activity was decreased in both these fractions. MAO activity increased significantly in CH, TH and HT. The presented results suggest a functional relationship between GABAergic (inhibitory), cholinergic and monoaminergic (excitatory) systems by affecting the rate of degradation of the excitatory neurotransmitters and Na+, K(+)-ATPase.

Acetylcholine↗

PubMed1997

Electrolyte disturbances due to ouabain sensitive sodium potassium pump in erythrocytes of children with sepsis.

The possible mechanism of hyponatraemia in septicaemic children was studied by measuring the intracellular red cell sodium in relation to ouabain sensitive Na(+)-K(+) pump by flame photometry. Hyponatraemia and hyperkalaemia were observed in most of the patients. There was a marked elevation in serum sodium levels and a significant reduction in serum potassium levels on recovery following therapy. The alteration in the distribution of electrolytes between plasma and erythrocytes resulted in significantly high levels of sodium and low levels of potassium within the erythrocytes of septicaemic patients which normalized on recovery. The ouabain sensitive sodium efflux rate and ouabain sensitive efflux rate constant were significantly decreased in the membranes of erythrocytes of septicaemic patients which also normalized on recovery. Our findings suggest that it is the intrinsic alterations in the transport capacity of Na(+)-K+ pump which could account for the rise in intracellular erythrocyte sodium and fall in intracellular potassium contents in septicaemic children.

Child↗

PubMed1997

Antiproliferative activity in vitro and in vivo of the spicamycin analogue KRN5500 with altered glycoprotein expression in vitro.

The spicamycin analogue KRN5500 (NSC 650426; SPA) is derived from Streptomyces alanosinicus. The unique structure contains a purine, an aminoheptose sugar, glycine, and a tetradecadiene fatty acid. SPA potently inhibits the growth of certain human tumor cell lines in vitro (IC50 for growth <100 nM) and displays marked activity in vivo in Colo 205 colon carcinoma xenografts. Selective inhibition of labeled precursor incorporation was not evident at 1 or 4 h of exposure to the drug, but at 8 h, [3H] leucine incorporation was inhibited by approximately 40% at or below the IC50 for cell growth. Because of the structural similarity of SPA to inhibitors of glycoprotein processing, we examined the effect of SPA on indicators of glycoprotein synthesis and processing in HL60TB promyelocytic leukemia and Colo 205 colon carcinoma cells. Brief periods of exposure ( approximately 30 min) to SPA at the IC50 for growth increased incorporation of [3H]mannose. When examined by Western blotting after prolonged (40-48 h) incubation with lectins that target mannose-containing carbohydrates, Galanthus nivalis agglutinin and concanavalin A, a qualitative change in the pattern of mannose-containing glycoproteins was observed in HL60TB cells. Significant changes in the pattern of surface glycoprotein expression in intact cells were demonstrated by flow cytometry using fluorescence-labeled lectins. An increase in the number of cells binding G. nivalis agglutinin (indicating terminal mannose) was noted, but a decrease in the amount of lectin bound per cell was noted for wheat germ agglutinin (detecting sialic acid and terminal beta-N-acetyl glucosamine residues). Electron microscopy revealed loss of microvilli, and the Golgi apparatus appeared inflated. Our findings, therefore, raise the possibility that cells exposed to SPA have altered glycoprotein processing after exposure to low concentrations of drug, prior to the occurrence of overt cytotoxicity. These effects are consistent with a prominent early effect of SPA on the enzymatic machinery or organelles important for proper glycoprotein processing and emphasize the novelty of this agent's likely mechanism of action.

Animals↗

PubMed1996

Molecular basis of pathophysiology of Indian childhood cirrhosis: role of nuclear copper accumulation in liver.

Indian Childhood Cirrhosis (ICC) is a disease of abnormal copper metabolism commonly characterized by swelling and degeneration of liver cells along with the presence of orcein staining deposits of copper. Hepatic copper content of ICC patients was about 43 fold higher than those of control subjects. The data on sub-cellular distribution of copper revealed massive accumulation of Copper (73%) of total cell copper) in the nuclear fraction (455 micrograms Cu/g tissue nuclei). On further distribution of copper in nuclear fraction, the enrichment of copper in heterochromatin and euchromatin of ICC nuclei was found to be 48 and 15 fold higher over control fractions respectively. The ultra-violet spectra of heterochromatin and euchromatin isolated from ICC nuclear fraction showed a broad absorption maxima as compared to controls. Further, A260/A280 ratio was markedly lower in heterochromatin and euchromatin of ICC liver in comparison to controls. An antioxidant enzyme, catalase activity was also significantly reduced in ICC liver as compared to control. Further, DNA fragmentation studies indicated that there was significantly increased DNA fragmentation in ICC liver. Collectively, these findings suggest that massive accumulation of copper in nucleus and decrease in catalase activity was associated with DNA fragmentation in hepatocyte of ICC disease.

Catalase↗

PubMed1996

Modulation of ouabain sensitive sodium potassium pump of erythrocytes from patients with chronic renal failure: role of acute hemodialysis.

Significantly higher levels of plasma urea creatinine and potassium were observed in patients with renal failure compared to normal controls. The RBC sodium concentration was raised whereas the RBC potassium concentration was decreased in chronic renal failure. These alterations in the RBC Na+ and K+ concentrations were associated with decrease in ouabain sensitive sodium efflux rate and ouabain sensitive sodium efflux rate constant. However, there was no significant impact of acute hemodialysis on the intracellular electrolytes levels, ouabain sensitive sodium efflux rate and ouabain sensitive sodium efflux rate constant. These findings suggest an intrinsic alteration in the transport capacity of Na(+)-K+ pump which could account for the rise in intracellular sodium and fall in intracellular potassium content in the RBCs of chronic renal failure patients.

Creatinine↗

PubMed1996

Altered physical state of p210bcr-abl in tyrphostin AG957-treated K562 cells.

AG957 is a tyrosine kinase antagonist which prior studies had shown inhibits p210bcr-abl tyrosine kinase activity and K562 chronic myelogenous leukemia cell growth. We report here the effects of AG957 on the physical state of p210bcr-abl and its signaling adapter molecules Shc and Grb2 in K562 cells. After exposure to AG957, the amount of tyrosine-phosphorylated native p210bcr-abl decreases, with the appearance of a high molecular weight (> 210 kDa) p210bcr-abl. This effect is seen after [32P]orthophosphate and [35S]methionine labeling. Material suggesting the involvement of p210bcr-abl in high molecular weight complexes also appears using anti-Shc, anti-Grb2 and anti-phosphotyrosine antibodies. AG957 also acts in vitro to shift native p210bcr-abl in anti-p210bcr-abl or anti-Grb2 immunoprecipitates to higher molecular weight forms under conditions where the drug can also act as an antagonist of p210bcr-abl autokinase activity. Incubation with dithiothreitol inhibits the appearance of > 210 kDa forms of p210bcr-abl in the in vitro reaction. These results leads to the hypothesis that AG957 does not act simply as a reversible tyrosine kinase antagonist, but can alter the normal amounts and physical associations of molecules important in tyrosine kinase signaling. These effects likely reflect covalent cross-links induced by the drug.

Animals↗

PubMed1995

Tyrphostin AG17, [(3,5-Di-tert-butyl-4-hydroxybenzylidene)- malononitrile], inhibits cell growth by disrupting mitochondria.

[(3,5-Di-tert-butyl-4-hydroxybenzylidene)-malononitrile] (AG17), a "tyrphostin" tyrosine kinase antagonist, was found to inhibit tumor cell growth with 50% growth inhibition ranging from 0.7 to 4.0 microM in a panel of 13 human tumor cell lines, as evaluated by tetrazolium dye reduction and inhibition of precursor incorporation into macromolecules. The promyelocytic leukemia cell line HL-60(TB), was the most sensitive with irreversible total growth inhibition after 12 h of exposure to 1.5 microM drug. Antiproliferative effects of AG17 in HL-60(TB) cells were temporally related to disruption of mitochondrial function, which occurred within 1 h after drug exposure as demonstrated by a significantly decreased mass of ATP in drug-treated cells, loss of the fluorescent mitochondrial membrane potential probe rhodamine 123, and ultrastructural examination of mitochondria using fluorescence and electron microscopy. Specific decreases of total or tyrosine-phosphorylated substrate at concentrations of the drug not affecting ATP levels were not detected. These data raise the possibility that AG17 may act in part by altering mitochondrial function and/or structure, and that impairment of mitochondrial function may be exploitable as a potentially useful mechanism to modulate tumor cell proliferation. This study also emphasizes the importance of evaluating carefully the effects of potential protein kinase antagonists, since these structures have effects in intact cells in addition to what might be expected from in vitro enzyme assays.

Adenosine Triphosphate↗

PubMed1995

Jasplakinolide's inhibition of the growth of prostate carcinoma cells in vitro with disruption of the actin cytoskeleton.

BACKGROUND: Jasplakinolide, a cyclodepsipeptide produced by an Indo-Pacific sponge, Jaspis johnstoni, has been reported to inhibit the growth of breast cancer cells. PURPOSE: The effects of jasplakinolide on the proliferation of three human immortalized prostate carcinoma cell lines (PC-3, LNCaP, and TSU-Pr1) were studied. The growth-inhibitory effect of jasplakinolide on the PC-3 cell line was studied in detail to elucidate its mechanism of action. METHODS: Cell counts were used to study growth inhibition. A protein-based microplate assay was used to assess the time of exposure needed to cause persistent growth inhibition and to study the effects of jasplakinolide analogues. Metabolic changes were assessed by following the incorporation of radiolabeled precursors. The effects of jasplakinolide on the cytoskeleton were studied by fluorescent microscopy, using rhodamine phalloidin (RP) and antibodies to cytoskeletal components. Changes in RP binding were quantified by extracting bound fluorescent material from fixed cells and measuring the amount of fluorescence in a spectrofluorometer. RESULTS: The growth of PC-3, LNCaP, and TSU-Pr1 cells was potently inhibited by exposure to jasplakinolide for 48 hours; doses of jasplakinolide that led to 50% growth inhibition were 65 nM for PC-3 cells, 41 nM for LNCaP cells, and 170 nM for TSU-Pr1 cells. In PC-3 cells, exposure to 160 nM for 48 hours led to total growth inhibition, which persisted for several days even after drug removal. Several jasplakinolide analogues also inhibited the growth of PC-3 cells, although analogues in which the rigidity of the macrolide ring was altered were ineffective. No early changes in the synthesis of DNA, RNA, or protein or in intracellular adenosine triphosphate levels were seen in the PC-3 cells after exposure to jasplakinolide. Growth inhibition by jasplakinolide was accompanied by striking morphologic changes. Exposure for several doublings led to multinucleated cells. Further investigation of these changes in the PC-3 cells revealed a dramatic and early disruption of the actin cytoskeleton and a statistically significant decrease in RP binding. The doses of jasplakinolide, the time of exposure, and the pattern of growth inhibition by structural analogues corresponded with the changes seen in actin distribution. CONCLUSIONS: Jasplakinolide represents a novel marine natural product with potent in vitro antiproliferative activity against human prostate carcinoma cell lines, and it appears to target the actin cytoskeleton. IMPLICATIONS: Jasplakinolide is a potential candidate for further preclinical development and a lead structure for a novel class of therapeutic agents that can disrupt the actin cytoskeleton in mammalian cells.

Actins↗

PubMed1995

Noise-free chemiluminescent detection of human T cell receptor and interleukin-2 receptor genes after optimization of digoxigenin labeled probe concentration.

Reduction in the background problems to improve the efficiency of nonradioactive labeling and detection procedure has been the focus of attention in the recent past for wider acceptance of the technique in nucleic acid research. We have achieved success in obtaining a relatively background free detection of single copy genes such as, T-cell receptor-delta (TCR-delta) and interleukin-2 receptor (L-2r) in human genome by using optimized concentrations of the digoxigenin labeled probes. Inclusion of such an optimization step for each probe before carrying out the actual hybridization experiment did not require any further modification in hybridization conditions and detection protocols as suggested earlier [Anal Biochem, 210 (1993) 235; Colloq Boehringer Mannheim, 2 (1991) 4.]

Blotting, Southern↗

PubMed1994

Changes in glucose metabolism from discrete regions of rat brain and its relationship to reproductive failure during experimental diabetes.

This study reports the effects of alloxan induced diabetes on glucose metabolism enzymes viz. Hexokinase, Lactate dehydrogenase, and Glucose-6-phosphate dehydrogenase from discrete brain regions. Enzymes activity was assayed from hypothalamic areas such as medial preoptic area and median eminence-arcuate region which have gonadotropin releasing hormone cell bodies and their terminals, respectively and other brain regions like septum, amygdala, hippocampus, and thalamus. In all the areas studied, induction of diabetes resulted in a significant decrease in particulate bound HK activity, whereas soluble HK, LDH and G6PDH activity showed increase at 3, 8, 15 and 28 days intervals. Insulin treatment of diabetic rats led to recovery in enzyme activity. Blood glucose levels increased significantly after induction of diabetes and recovery was seen after insulin treatment. The present results suggest that altered cerebral glucose metabolism may also be responsible for reproductive failure observed in diabetic rats.

Alloxan↗

PubMed1994

Potent inhibition of CDC2 kinase activity by the flavonoid L86-8275.

L86-8275 [(-) cis-5,7-dihydroxy-2-(2-chlorophenyl)-8[4-(3-hydroxy-1- methyl)-piperidinyl]-4H-benzopyran-4-one] directly inhibits immunoprecipitated Cdc2 kinase activity from G2/M synchronized MDA-MB-468 breast carcinoma cells and is at least 250-fold more potent than either quercetin or genistein. Purified sea-star Cdc2 kinase (IC50 = 0.5 microM) was inhibited with a similar potency to immunoprecipitated Cdc2 kinase from MDA-MB-468 cells (IC50 = 0.4 microM). This inhibition was competitive with respect to ATP (KiATP = 0.041 microM) and noncompetitive with respect to a synthetic peptide substrate, CDK1S1 (AAKAKKTPKKAKK-CONH2, KiCDK1S1 = 0.14 microM). These data suggest L86-8275 as a lead structure for the development of inhibitors of the cyclin-dependent kinases.

Adenosine Triphosphate↗

PubMed1994

Acetylcholinesterase and Na+,K(+)-ATPase activities in different regions of rat brain during insulin-induced hypoglycemia.

The activities of acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7), responsible for hydrolysis of acetylcholine and Na+,K(+)-ATPase (Mg(2+)-dependent ATP phosphohydrolase, EC 3.6.1.3), which plays a crucial role in neurotransmission, were determined in four brain regions after 1, 2, and 3 h of insulin administration. Significant decrease in the acetylcholinesterase and Na+,K(+)-ATPase activities was observed in the soluble and total particulate fractions from cerebral hemispheres, cerebellum, brain stem, and diencephalon + basal ganglia after 1, 2, and 3 h of insulin-induced hypoglycemia. Blood glucose level decreased significantly after 1 h of insulin administration and remained at low level for 2 h thereafter, whereas, the protein content in different subcellular fractions from four brain regions did not show any significant change under this physiological stress.

Acetylcholinesterase↗

PubMed1994

Effect of alloxan-induced diabetes on acetylcholinesterase activity from discrete areas of rat brain.

The effect of experimental diabetes induced in rats was examined in brain areas like the septum, medial preoptic area, median eminence-arcuate region, amygdala, thalamus, hippocampus, pons and medulla. In all the areas studied, acute hyperglycemia caused an increase in the activity of acetylcholinesterase, the degradative enzyme of cholinergic system, whereas insulin administration reversed this effect. These findings suggest that the dysfunction of cholinergic system may also be involved in the diabetes associated CNS complications.

Acetylcholinesterase↗

PubMed1994

Effect of alloxan-induced diabetes on Na+, K(+)-ATPase activity from discrete areas of the rat brain.

The effect of alloxan-induced diabetes was studied on the activity of Na+, K(+)-ATPase enzyme which is involved in numerous reactions in the metabolism of the synaptic region, Na+, K(+)-ATPase activity was examined in brain areas such as septum, amygdala, thalamus, hippocampus, pons and medulla, and in hypothalamic areas such as medial preoptic and median eminence-arcuate region. In all these areas studied, diabetes caused a decrease in the activity of Na+, K(+)-ATPase, whereas, insulin administration reversed this effect. The present results may indicate the possible involvement of Na+, K(+)-ATPase in neuropathophysiology of diabetes.

Amygdala↗