Shakeel Farooqui - Academia.edu (original) (raw)

Papers by Shakeel Farooqui

Springer eBooks, 1981

Marginal deficiency of vitamin B6 has been shown to promote hyperoxaluria in man1. Even though la... more Marginal deficiency of vitamin B6 has been shown to promote hyperoxaluria in man1. Even though large doses of pyridoxine may reduce the hyperoxaluria1, the dose of pyridoxine to be administered has not been well defined. Hyperoxaluria in animals can be induced by ethylene glycol or sodium glycolate2. The present study has been undertaken to find out the effect of large doses of pyridoxine on ethylene glycol-induced hyperoxaluria in rats and also in hyperoxaluric stone-forming patients.

Calcium oxalate is the most common lithogenic substance found in human urinary calculi1. Hyperoxa... more Calcium oxalate is the most common lithogenic substance found in human urinary calculi1. Hyperoxaluria has been observed in pyridoxine-deficiency and is presumably due to the increased endogenous synthesis of oxalate2,3 or to the increased bioavailability of dietary oxalate4,5. Oxalate uptake follows a biphasic transport mechanism. In vitamin B6-deficient rats, at low oxalate concentrations (0.1 to 0.8 mM), a saturable oxalate transport system (OTS) operates, while at higher concentrations of oxalate (0.8 to 6 mM), its uptake follows a passive diffusion mechanism5. Carrier-mediated OTS is inhibited by protein synthesis inhibitors and glycolate or glyoxylate competitively inhibits oxalate transport4. To understand the mechanism of this uptake process the effect of other mono- and dicarboxylic acids on the saturable oxalate transport system and calcium uptake in pyridoxine-deficient rats has been investigated.

PubMed, 1987

Fusion of normal human, goat, bovine and chicken erythrocytes was investigated using the phosphat... more Fusion of normal human, goat, bovine and chicken erythrocytes was investigated using the phosphate-calcium protocol. The relative effects on fusion efficiency of cell shape, membrane deformability, and composition and orientation of phospholipids in the lipid bilayer were ascertained. Exposure of red blood cells to phosphate ions followed by calcium led to cell agglutination at room temperature for all species. Incubation at 37 degrees C for periods up to 2 hours caused hemolysis and membrane-associated protein aggregation followed by fusion in human and chicken erythrocytes but not in bovine or goat red cells. Cell shape may not be a determinant in fusion since bovine, like human erythrocytes, are biconcave but do not fuse with the above protocol. Bovine and goat red blood cells lack phosphatidylcholine in their membranes. Incorporation of phosphatidylcholine into bovine red blood cells, mediated by a specific transfer protein, promoted their fusion. Our results indicate the important role played by phospholipid composition and orientation in red cell membranes for fusion by phosphate and calcium.

PubMed, 1986

Dietary deficiency of thiamine or pyridoxine has been shown to produce hyperoxaluria and renal st... more Dietary deficiency of thiamine or pyridoxine has been shown to produce hyperoxaluria and renal stone formation in man and experimental animals. To determine the possible contribution of exogenous glyoxylate and oxalate, the intestinal transport of [14C] - oxalate and [14C] - glyoxylate was measured in vitamin B1 and B6 deficient rats and their respective pair-fed controls. Results indicate that glyoxylate and oxalate are passively diffused from lumen to lamina propria in thiamine deficient and their pair-fed controls with no significant change in the rate of uptake of both the substrates. However B6 deficient rats showed a significant enhancement in the rate of oxalate uptake due to development of a new biphasic transport system. The rate of glyoxylate uptake by simple passive diffusion remained unaltered in pyridoxine deficiency.

Springer eBooks, 1985

Hyperabsorption of oxalate from the gut has been shown to be an important contributory factor in ... more Hyperabsorption of oxalate from the gut has been shown to be an important contributory factor in the production of calcium oxalate urolithiasis1, a disease which is more prevalent in men than women2. Sex hormones regulate the enzymes of oxalate biosynthesis in the glycolate-glyoxylate-oxalate pathways3,4. To elucidate the role of sex hormones in the intestinal uptake of oxalate, male and female rats were gonadectomized and treated with estradiol and testosterone respectively.

PubMed, 1983

Radiolabelled U-14C oxalic acid uptake was measured in the intestine of scorbutic and ascorbic ac... more Radiolabelled U-14C oxalic acid uptake was measured in the intestine of scorbutic and ascorbic acid (AA) supplemented guinea pigs. The feeding of vitamin C deficient diet to the animals for 26 days resulted in a significant fall in the ascorbic acid levels in the various tissues studied. Supplementation of vitamin C (10, 25 or 50 mg per 200 g body weight) increased ascorbic acid levels of spleen, adrenals, liver and leucocytes. The intestinal uptake of oxalate follows a passive diffusion mechanism in normally fed guinea pigs. The oxalate uptake rate was significantly increased (p less than 0.001) in the vitamin C administered group. Vitamin C depletion significantly decreased the oxalate uptake rate as compared to control animals. The changes observed in the uptake rate appear to be related with the chemical aberrations produced in the brush border membranes.

PubMed, Sep 1, 1982

Twelve recurrent stone formers with hyperoxaluria were administered pyridoxine-HCl (10 mg/day) da... more Twelve recurrent stone formers with hyperoxaluria were administered pyridoxine-HCl (10 mg/day) daily for a period of 180 days. The pyridoxine status of the patients, as assessed by their erythrocyte transaminase activation indexes, improved significantly (p less than 0.001) after 180 days of supplementation as compared with the basal levels. Although urinary oxalate decreased significantly (p less than 0.05) by the 90th day of pyridoxine therapy, other parameters, e.g., urinary calcium, phosphorus, and creatinine, remained unaltered. Significant correlation was observed between erythrocyte glutamate pyruvate transaminase (EGPT) or erythrocyte glutamate oxaloacetate transaminase (EGOT) activation index and urinary oxalate excretion (p less than 0.01). Pyridoxine in low doses (10 mg/day) is of therapeutic value for hyperoxaluric stone formers.

Biochemical Journal, Jun 1, 1991

Haemopexin receptors from mouse hepatoma (Hepa) cells were affinity-labelled by cross-linking to ... more Haemopexin receptors from mouse hepatoma (Hepa) cells were affinity-labelled by cross-linking to haem-125I-haemopexin complexes using two homo-[disuccinimidyl suberate (DSS) and 3,3'-dithiobis(succinimidyl propionate) (DTSSP)] and one hetero-[sulphosuccinimidyl 4-(p-maleimidophenyl)butyrate (sulpho-SMPB)] bifunctional cross-linking agents. Analysis of the cross-linked products by SDS/PAGE in the absence of reducing agents revealed that 125I-haemopexin was cross-linked specifically to a protein of apparent molecular mass 85-90 kDa. Upon reduction, haemopexin remained cross-linked to a protein of 20 kDa, suggesting that the murine haemopexin receptor has a subunit structure. Two subunits were identified: alpha (p65) and beta (p20). Furthermore, because haemopexin was cross-linked by all three agents to p20, the shortest cross-linker arm being 1.1 nm (11 A), we propose that the haem-haemopexin-binding site resides on this subunit. In addition, a cysteine residue of p20 is located near the haemopexin-binding site, since haemopexin, which has no free thiol groups, is cross-linked to this subunit by the hetero-bifunctional agent sulpho-SMPB. Exposure of Hepa cells to the tumour-promoting phorbol ester 4 alpha-phorbol 12-myristate 13-acetate (PMA) causes a rapid redistribution of haemopexin receptors from the cell surface to the cell interior. Within 2-4 min of incubation with 100 nM-PMA, there was an approx. 50% decrease in cell-surface haemopexin receptors, as judged by ligand binding at 0 degrees C and affinity labelling of the receptor. This time- and dose-dependent down-regulation was fully reversible within 60-90 min after removal of PMA, and the affinity of the remaining receptors was unaltered by PMA. The specificity of PMA was demonstrated by comparison with the non-tumour-promoter 4 alpha-phorbol, which did not affect any of the parameters examined. The amine H-7, a specific inhibitor of protein kinase C, antagonised the receptor redistribution effect of PMA, suggesting that the down-regulation of haemopexin receptors on the cell surface was a consequence of protein kinase C activation. The PMA-induced decrease in surface haemopexin receptors was due to a 2-fold increase in the rate of internalization (from 0.73 min-1 to 1.32 min-1), whereas the rate of exocytosis (0.6 min-1) was unchanged. PMA treatment, like binding of the natural ligand, haem-haemopexin, results in a lower steady-state level of surface haemopexin receptors independent of receptor synthesis, and the receptors were not degraded but were recycled back to the cell surface.

Springer eBooks, 1981

Northern India has a high incidence of stone disease and nearly 96% of these stones contain calci... more Northern India has a high incidence of stone disease and nearly 96% of these stones contain calcium oxalate1. Several reports have suggested that the primary cause of stone-formation is the hyper- absorption of oxalate2 due to the marginal nutritional deficiency of vitamin B6 3. In this study the effect of B6 deficiency on the intestinal absorption and the renal clearance of oxalate has been studied along with the mechanism of its transport.

PubMed, Jun 1, 1981

Nutrition & urolithiasis: Part I-intestinal absorption of oxalate in vitamin B6 deficient rat... more Nutrition & urolithiasis: Part I-intestinal absorption of oxalate in vitamin B6 deficient rats. ... There are no files associated with this item. ... Items in IMSEAR Digital Repository are protected by copyright, with all rights reserved, unless otherwise indicated. ... Index Medicus for South-...

Biochemical Medicine, Aug 1, 1984

[U-14C]oxalic acid and 45Ca uptake was measured in control and vitamin B6-deficient rats. Calcium... more [U-14C]oxalic acid and 45Ca uptake was measured in control and vitamin B6-deficient rats. Calcium and oxalate uptake rates were significantly increased from the intestine of vitamin B6-deficient rats as compared to pair-fed controls. Oxalate uptake in pair-fed control rats follows a passive diffusion. In pyridoxine-deficient rats, the oxalate uptake increases nonlinearly as the oxalate concentration in the incubation medium increased, indicating a two-component system--a saturable sodium-independent uptake and a linear nonsaturable passive-diffusion component. The brush border membrane composition reveals that membrane sialic acid, cholesterol, and protein contents were markedly reduced. These aberrations in the chemical composition of brush border membrane may be responsible for the enhanced oxalic acid uptake in vitamin B6-deficient rats.

Biochemical Medicine, Oct 1, 1985

The effect of isatin (indole-2,3-dione) on D-glucose uptake has been studied in rat intestine. Is... more The effect of isatin (indole-2,3-dione) on D-glucose uptake has been studied in rat intestine. Isatin at 6 mM concentration significantly inhibited both the sugar uptake and transmural (mucosal to serosal side) transport in the intestine. The suppression of glucose uptake by isatin was irreversible. Similar to the action of various SH-group-reacting agents, isatin inhibited the sugar uptake, presumably by binding to membrane sulfhydryl groups through a covalent linkage. Isatin-induced reduction in glucose uptake was unaffected by pH (between 5.5 and 8.4) and by DTT addition to incubation medium. Inhibition of sugar uptake by isatin and harmaline was additive in nature; this suggested that these compounds interact at different sites on the microvillus membrane surface.

Indian journal of experimental biology, 1984

1. Indian J Exp Biol. 1984 Oct;22(10):555-6. Evidence of increased intestinal absorption of oxala... more 1. Indian J Exp Biol. 1984 Oct;22(10):555-6. Evidence of increased intestinal absorption of oxalate in rats induced for bladder stone. Farooqui S, Thind SK, Nath R, Mahmood A. PMID: 6530252 [PubMed - indexed for MEDLINE]. MeSH Terms: ...

Molecular Aspects of Medicine, 1984

Action of vitamin D and parathyroid hormone in relation to calcium and phosphorus metabolism 4.1.... more Action of vitamin D and parathyroid hormone in relation to calcium and phosphorus metabolism 4.1.2.2. Effect of vitamin D on the transmembrane calcium and phosphate fluxes 4.

Nutritional Neuroscience, 1998

In a previous report we demonstrated that rats that consumed a high-protein diet (HP; 50% casein)... more In a previous report we demonstrated that rats that consumed a high-protein diet (HP; 50% casein) for 36 weeks were hyperactive and hyperresponsive to nociceptive stimuli, compared to rats that consumed normal (NP; 20% casein) or low-protein (LP; 8% casein) diets. In addition, we have also previously, reported that dopamine concentrations in the nigrostriatal system of the rats were decreased and increased, respectively, with a decrease and increase in dietary protein. In the present study, rats were maintained on the HP, NP and LP diets and regional changes in the concentrations of norepinephrine (NE) and serotonin (5-hydroxytryptamine, 5-HT) were assessed. Concentrations of 5-HT in the medial raphe, dorsal raphe, and several of their target tissues, revealed no consistent effect of manipulating dietary protein over the range of 5-HT levels measured. NE concentrations in most of the brain regions innervated by neurons of the locus coeruleus and lateral tegmentum showed no significant differences among the diet groups. However, NE concentrations in the parietal cortex were significantly increased in rats that consumed the HP diet. The present study indicates that the brain NE pathways, particularly that innervating the parietal cortex, is susceptible to dietary protein manipulation.

Biochemistry international, 1984

The intestinal uptake rate of oxalate (mumoles/h/g tissue wt.) in castrated male (CM) rats, CM ra... more The intestinal uptake rate of oxalate (mumoles/h/g tissue wt.) in castrated male (CM) rats, CM rats administered estradiol, and female (F) rats was 1.8, 1.4 and 1.3 times higher than that of male rats, whereas castrated female (CF) rats and CF rats administered testosterone absorbed oxalate at a rate similar to F rats, thereby, suggesting that gonadectomy affected intestinal uptake of oxalate only in male rats The intestinal oxalate uptake rate in all the groups increased linearly with increasing oxalate concentration (0.1- 6.0 mM). Chemical composition of brush border membrane showed significant changes in the sialic acid, phospholipid and cholesterol content following castration, which may lead to ultrastructural changes in the membrane thereby, increasing the absorption of oxalate.

Journal of Clinical Oncology

2530 Background: Virtually all cancer treatments that kill cancer cells also adversely affect nor... more 2530 Background: Virtually all cancer treatments that kill cancer cells also adversely affect normal cells and often have debilitating side effects. A key challenge has been to identify antigens that are suitable for antibody-based targeted therapeutics. We have developed a novel platform to detect and identify multiple cell surface antigens that are unique to human cancers. Methods: Breast Cancer cells (Hs578T) or Melanoma cells (Hs895.T) were injected into rabbits to generate polyclonal xeno-antibodies. The resulting serum against each cancer was then incubated with normal cells of the same tissue type derived from the same patients; Breast Epithelium (matched-pair Hs578Bst) or Skin Fibroblasts (matched-pair Hs895.Sk) in order to absorb antibodies that cross-react with antigens on normal tissue (U.S. Patent Application No. 16/243,161). Flow cytometry was used for measuring the binding capacity of the unfiltered serum and filtered serum (lacking cross-reacting antibodies) on both t...

Bba Biomembranes, 1987

Two kinds of membrane (luminal and abluminal membrane domains) fractions have been isolated from ... more Two kinds of membrane (luminal and abluminal membrane domains) fractions have been isolated from bovine aortic endothelial cells by fractionation of whole cell homogenate on discontinuous sucrose density gradients. The luminal membrane domain was enriched 12-16-fold for angiotensin-converting enzyme activity and 8-10-fold in alkaline phosphatase activity. The abluminal membrane domain displayed an enrichment of 8-fold in (Na++ K+)-ATPase activity. Both of the membrane domains were minimally contaminated with mitochondria, microsomes and Goigi bodies, as assessed by their corresponding marker enzyme activities. 125I-labeling of endothelial cell monolayers by the Enzymo-Bead lactoperoxidase-catalyzed iodination procedure, followed by isolation of membranes, revealed that the radioactivity was predominantly associated with membranes enriched in angiotensin-converting enzyme activity, corresponding to the luminal membrane domain. However, when cells were radioiodinated in suspension culture, radioactivity was found equally associated in both the luminal and abluminal membrane fractions. Electron microscopy of freeze-fractured and sectioned material showed both luminal and abluminal membrane domains to be in the form of vesicles varying in size from 100 to 400 nm in diameter. To characterize the separation of endothelial cell membrane domains, we have attempted to prepare monoclonal antibodies specific for endothelial cells. Several clones were obtained, producing antibodies which bound to endothelial cells of arterial, venous and capillary origin. Two antibodies of these clones, XIVC 6 and XVD2, were studied in more detail. In the ELISA assay, these antibodies reacted with bovine vascular endothelial cells, but not with human umbilical cord endothelial cells, nor with bovine corneal endothelial cells, smooth muscle cells or flbroblasts. Both of these antibodies are directed against an antigen of approximately 130 kDa, under reducing and non-reducing conditions, as assayed by the immunoprecipitation method. Western blot analysis of luminal and abluminal membrane fractions revealed that only MAb XVD 2 reacted with an antigen, indicating that the antibody XIVC 6 is directed against an epitope which is denatured by SDS. Moreover, Abbreviations: BAEC, bovine aortic endothelial cells; GAM-FITC, goat antimouse Ig, fluorescein isothiocyanate (FITC) conjugated; ELISA, enzyme-linked immunosorbent assay.

J Neurochem, 2002

In a previous study, it was observed that the activity of rolipram-sensitive, low-Km, cyclic AMP ... more In a previous study, it was observed that the activity of rolipram-sensitive, low-Km, cyclic AMP phosphodiesterase (PDE4) was decreased in vivo with diminished noradrenergic stimulation. The results of the present experiments indicated that the reduction in the activity may be associated with down-regulation of PDE4 protein. Immunoblot analysis using PDE4-specific, subfamily-nonspecific antibody (K116) revealed four major bands of PDE4 in rat cerebral cortex; those with apparent molecular masses of 109 and 102 kDa are variants of PDE4A. Diminished noradrenergic activity, produced by intracerebroventricular infusion of 6-hydroxydopamine (6-OHDA) or chronic subcutaneous infusion of propranolol, decreased the intensities of the protein bands for the 109- and 102-kDa PDE4A variants in rat cerebral cortex but not of the 98- or 91-kDa PDE4 forms. 6-OHDA-induced noradrenergic lesioning also decreased the content of 102-kDa PDE4A in hippocampus as labeled by PDE4A-specific antibody (C-PDE4A). Enhanced noradrenergic stimulation up-regulated PDE4 in cerebral cortex. This was indicated by the finding that repeated treatment with desipramine increased the intensity of the protein band for the 102-kDa PDE4 but not for the other variants of PDE4. These results suggest that PDE4 subtypes are differentially regulated at the level of expression, as evidenced by an apparent change in the amount of PDE4 protein, following changes in noradrenergic activity. These observations are consistent with the notion that PDE4s, especially the PDE4A variants with molecular masses of 109 and 102 kDa, play an important role in maintaining the homeostasis of the noradrenergic signal transduction system in the brain and may be involved in the mediation of antidepressant activity.

Brain Research, May 1, 1992

The precise distribution of the dopamine type D2 receptor has been mapped for the first time in r... more The precise distribution of the dopamine type D2 receptor has been mapped for the first time in rat brain using an antibody to D2 receptor protein. Polyclonal antisera were collected from rabbits inoculated with an undecapeptide identical to residues 24-34 of the D2 protein sequence. Rat brain slices, 40 microns in thickness, were incubated with either primary antiserum, the antiserum plus free peptide antigen, or pre-immune serum. Antibody binding was visualized by peroxidase-antiperoxidase (PAP) reaction followed by light microscopy. PAP complex bound moderately-to-densely throughout the medial forebrain bundle, and was seen in more discrete regions in the midbrain, consistent with the binding of D2 radioligands. There were some unexpected results, namely in the cerebral cortex and nucleus accumbens, there were unexpectedly steep gradients in binding density, decreasing caudally; no binding was detected in the hippocampus or the substantia nigra pars reticulata. In all positive-staining regions examined, the antibody was highly localized to neuronal cell bodies, except in the frontal cortex where antibody was also evident on basilar dendrites. These data confirm that the polyclonal antibody recognized dopamine D2 receptor protein throughout the rat brain, and suggest that the D2 receptor is distributed more abundantly on somata than on cellular processes.

Springer eBooks, 1981

Marginal deficiency of vitamin B6 has been shown to promote hyperoxaluria in man1. Even though la... more Marginal deficiency of vitamin B6 has been shown to promote hyperoxaluria in man1. Even though large doses of pyridoxine may reduce the hyperoxaluria1, the dose of pyridoxine to be administered has not been well defined. Hyperoxaluria in animals can be induced by ethylene glycol or sodium glycolate2. The present study has been undertaken to find out the effect of large doses of pyridoxine on ethylene glycol-induced hyperoxaluria in rats and also in hyperoxaluric stone-forming patients.

Calcium oxalate is the most common lithogenic substance found in human urinary calculi1. Hyperoxa... more Calcium oxalate is the most common lithogenic substance found in human urinary calculi1. Hyperoxaluria has been observed in pyridoxine-deficiency and is presumably due to the increased endogenous synthesis of oxalate2,3 or to the increased bioavailability of dietary oxalate4,5. Oxalate uptake follows a biphasic transport mechanism. In vitamin B6-deficient rats, at low oxalate concentrations (0.1 to 0.8 mM), a saturable oxalate transport system (OTS) operates, while at higher concentrations of oxalate (0.8 to 6 mM), its uptake follows a passive diffusion mechanism5. Carrier-mediated OTS is inhibited by protein synthesis inhibitors and glycolate or glyoxylate competitively inhibits oxalate transport4. To understand the mechanism of this uptake process the effect of other mono- and dicarboxylic acids on the saturable oxalate transport system and calcium uptake in pyridoxine-deficient rats has been investigated.

PubMed, 1987

Fusion of normal human, goat, bovine and chicken erythrocytes was investigated using the phosphat... more Fusion of normal human, goat, bovine and chicken erythrocytes was investigated using the phosphate-calcium protocol. The relative effects on fusion efficiency of cell shape, membrane deformability, and composition and orientation of phospholipids in the lipid bilayer were ascertained. Exposure of red blood cells to phosphate ions followed by calcium led to cell agglutination at room temperature for all species. Incubation at 37 degrees C for periods up to 2 hours caused hemolysis and membrane-associated protein aggregation followed by fusion in human and chicken erythrocytes but not in bovine or goat red cells. Cell shape may not be a determinant in fusion since bovine, like human erythrocytes, are biconcave but do not fuse with the above protocol. Bovine and goat red blood cells lack phosphatidylcholine in their membranes. Incorporation of phosphatidylcholine into bovine red blood cells, mediated by a specific transfer protein, promoted their fusion. Our results indicate the important role played by phospholipid composition and orientation in red cell membranes for fusion by phosphate and calcium.

PubMed, 1986

Dietary deficiency of thiamine or pyridoxine has been shown to produce hyperoxaluria and renal st... more Dietary deficiency of thiamine or pyridoxine has been shown to produce hyperoxaluria and renal stone formation in man and experimental animals. To determine the possible contribution of exogenous glyoxylate and oxalate, the intestinal transport of [14C] - oxalate and [14C] - glyoxylate was measured in vitamin B1 and B6 deficient rats and their respective pair-fed controls. Results indicate that glyoxylate and oxalate are passively diffused from lumen to lamina propria in thiamine deficient and their pair-fed controls with no significant change in the rate of uptake of both the substrates. However B6 deficient rats showed a significant enhancement in the rate of oxalate uptake due to development of a new biphasic transport system. The rate of glyoxylate uptake by simple passive diffusion remained unaltered in pyridoxine deficiency.

Springer eBooks, 1985

Hyperabsorption of oxalate from the gut has been shown to be an important contributory factor in ... more Hyperabsorption of oxalate from the gut has been shown to be an important contributory factor in the production of calcium oxalate urolithiasis1, a disease which is more prevalent in men than women2. Sex hormones regulate the enzymes of oxalate biosynthesis in the glycolate-glyoxylate-oxalate pathways3,4. To elucidate the role of sex hormones in the intestinal uptake of oxalate, male and female rats were gonadectomized and treated with estradiol and testosterone respectively.

PubMed, 1983

Radiolabelled U-14C oxalic acid uptake was measured in the intestine of scorbutic and ascorbic ac... more Radiolabelled U-14C oxalic acid uptake was measured in the intestine of scorbutic and ascorbic acid (AA) supplemented guinea pigs. The feeding of vitamin C deficient diet to the animals for 26 days resulted in a significant fall in the ascorbic acid levels in the various tissues studied. Supplementation of vitamin C (10, 25 or 50 mg per 200 g body weight) increased ascorbic acid levels of spleen, adrenals, liver and leucocytes. The intestinal uptake of oxalate follows a passive diffusion mechanism in normally fed guinea pigs. The oxalate uptake rate was significantly increased (p less than 0.001) in the vitamin C administered group. Vitamin C depletion significantly decreased the oxalate uptake rate as compared to control animals. The changes observed in the uptake rate appear to be related with the chemical aberrations produced in the brush border membranes.

PubMed, Sep 1, 1982

Twelve recurrent stone formers with hyperoxaluria were administered pyridoxine-HCl (10 mg/day) da... more Twelve recurrent stone formers with hyperoxaluria were administered pyridoxine-HCl (10 mg/day) daily for a period of 180 days. The pyridoxine status of the patients, as assessed by their erythrocyte transaminase activation indexes, improved significantly (p less than 0.001) after 180 days of supplementation as compared with the basal levels. Although urinary oxalate decreased significantly (p less than 0.05) by the 90th day of pyridoxine therapy, other parameters, e.g., urinary calcium, phosphorus, and creatinine, remained unaltered. Significant correlation was observed between erythrocyte glutamate pyruvate transaminase (EGPT) or erythrocyte glutamate oxaloacetate transaminase (EGOT) activation index and urinary oxalate excretion (p less than 0.01). Pyridoxine in low doses (10 mg/day) is of therapeutic value for hyperoxaluric stone formers.

Biochemical Journal, Jun 1, 1991

Haemopexin receptors from mouse hepatoma (Hepa) cells were affinity-labelled by cross-linking to ... more Haemopexin receptors from mouse hepatoma (Hepa) cells were affinity-labelled by cross-linking to haem-125I-haemopexin complexes using two homo-[disuccinimidyl suberate (DSS) and 3,3'-dithiobis(succinimidyl propionate) (DTSSP)] and one hetero-[sulphosuccinimidyl 4-(p-maleimidophenyl)butyrate (sulpho-SMPB)] bifunctional cross-linking agents. Analysis of the cross-linked products by SDS/PAGE in the absence of reducing agents revealed that 125I-haemopexin was cross-linked specifically to a protein of apparent molecular mass 85-90 kDa. Upon reduction, haemopexin remained cross-linked to a protein of 20 kDa, suggesting that the murine haemopexin receptor has a subunit structure. Two subunits were identified: alpha (p65) and beta (p20). Furthermore, because haemopexin was cross-linked by all three agents to p20, the shortest cross-linker arm being 1.1 nm (11 A), we propose that the haem-haemopexin-binding site resides on this subunit. In addition, a cysteine residue of p20 is located near the haemopexin-binding site, since haemopexin, which has no free thiol groups, is cross-linked to this subunit by the hetero-bifunctional agent sulpho-SMPB. Exposure of Hepa cells to the tumour-promoting phorbol ester 4 alpha-phorbol 12-myristate 13-acetate (PMA) causes a rapid redistribution of haemopexin receptors from the cell surface to the cell interior. Within 2-4 min of incubation with 100 nM-PMA, there was an approx. 50% decrease in cell-surface haemopexin receptors, as judged by ligand binding at 0 degrees C and affinity labelling of the receptor. This time- and dose-dependent down-regulation was fully reversible within 60-90 min after removal of PMA, and the affinity of the remaining receptors was unaltered by PMA. The specificity of PMA was demonstrated by comparison with the non-tumour-promoter 4 alpha-phorbol, which did not affect any of the parameters examined. The amine H-7, a specific inhibitor of protein kinase C, antagonised the receptor redistribution effect of PMA, suggesting that the down-regulation of haemopexin receptors on the cell surface was a consequence of protein kinase C activation. The PMA-induced decrease in surface haemopexin receptors was due to a 2-fold increase in the rate of internalization (from 0.73 min-1 to 1.32 min-1), whereas the rate of exocytosis (0.6 min-1) was unchanged. PMA treatment, like binding of the natural ligand, haem-haemopexin, results in a lower steady-state level of surface haemopexin receptors independent of receptor synthesis, and the receptors were not degraded but were recycled back to the cell surface.

Springer eBooks, 1981

Northern India has a high incidence of stone disease and nearly 96% of these stones contain calci... more Northern India has a high incidence of stone disease and nearly 96% of these stones contain calcium oxalate1. Several reports have suggested that the primary cause of stone-formation is the hyper- absorption of oxalate2 due to the marginal nutritional deficiency of vitamin B6 3. In this study the effect of B6 deficiency on the intestinal absorption and the renal clearance of oxalate has been studied along with the mechanism of its transport.

PubMed, Jun 1, 1981

Nutrition & urolithiasis: Part I-intestinal absorption of oxalate in vitamin B6 deficient rat... more Nutrition & urolithiasis: Part I-intestinal absorption of oxalate in vitamin B6 deficient rats. ... There are no files associated with this item. ... Items in IMSEAR Digital Repository are protected by copyright, with all rights reserved, unless otherwise indicated. ... Index Medicus for South-...

Biochemical Medicine, Aug 1, 1984

[U-14C]oxalic acid and 45Ca uptake was measured in control and vitamin B6-deficient rats. Calcium... more [U-14C]oxalic acid and 45Ca uptake was measured in control and vitamin B6-deficient rats. Calcium and oxalate uptake rates were significantly increased from the intestine of vitamin B6-deficient rats as compared to pair-fed controls. Oxalate uptake in pair-fed control rats follows a passive diffusion. In pyridoxine-deficient rats, the oxalate uptake increases nonlinearly as the oxalate concentration in the incubation medium increased, indicating a two-component system--a saturable sodium-independent uptake and a linear nonsaturable passive-diffusion component. The brush border membrane composition reveals that membrane sialic acid, cholesterol, and protein contents were markedly reduced. These aberrations in the chemical composition of brush border membrane may be responsible for the enhanced oxalic acid uptake in vitamin B6-deficient rats.

Biochemical Medicine, Oct 1, 1985

The effect of isatin (indole-2,3-dione) on D-glucose uptake has been studied in rat intestine. Is... more The effect of isatin (indole-2,3-dione) on D-glucose uptake has been studied in rat intestine. Isatin at 6 mM concentration significantly inhibited both the sugar uptake and transmural (mucosal to serosal side) transport in the intestine. The suppression of glucose uptake by isatin was irreversible. Similar to the action of various SH-group-reacting agents, isatin inhibited the sugar uptake, presumably by binding to membrane sulfhydryl groups through a covalent linkage. Isatin-induced reduction in glucose uptake was unaffected by pH (between 5.5 and 8.4) and by DTT addition to incubation medium. Inhibition of sugar uptake by isatin and harmaline was additive in nature; this suggested that these compounds interact at different sites on the microvillus membrane surface.

Indian journal of experimental biology, 1984

1. Indian J Exp Biol. 1984 Oct;22(10):555-6. Evidence of increased intestinal absorption of oxala... more 1. Indian J Exp Biol. 1984 Oct;22(10):555-6. Evidence of increased intestinal absorption of oxalate in rats induced for bladder stone. Farooqui S, Thind SK, Nath R, Mahmood A. PMID: 6530252 [PubMed - indexed for MEDLINE]. MeSH Terms: ...

Molecular Aspects of Medicine, 1984

Action of vitamin D and parathyroid hormone in relation to calcium and phosphorus metabolism 4.1.... more Action of vitamin D and parathyroid hormone in relation to calcium and phosphorus metabolism 4.1.2.2. Effect of vitamin D on the transmembrane calcium and phosphate fluxes 4.

Nutritional Neuroscience, 1998

In a previous report we demonstrated that rats that consumed a high-protein diet (HP; 50% casein)... more In a previous report we demonstrated that rats that consumed a high-protein diet (HP; 50% casein) for 36 weeks were hyperactive and hyperresponsive to nociceptive stimuli, compared to rats that consumed normal (NP; 20% casein) or low-protein (LP; 8% casein) diets. In addition, we have also previously, reported that dopamine concentrations in the nigrostriatal system of the rats were decreased and increased, respectively, with a decrease and increase in dietary protein. In the present study, rats were maintained on the HP, NP and LP diets and regional changes in the concentrations of norepinephrine (NE) and serotonin (5-hydroxytryptamine, 5-HT) were assessed. Concentrations of 5-HT in the medial raphe, dorsal raphe, and several of their target tissues, revealed no consistent effect of manipulating dietary protein over the range of 5-HT levels measured. NE concentrations in most of the brain regions innervated by neurons of the locus coeruleus and lateral tegmentum showed no significant differences among the diet groups. However, NE concentrations in the parietal cortex were significantly increased in rats that consumed the HP diet. The present study indicates that the brain NE pathways, particularly that innervating the parietal cortex, is susceptible to dietary protein manipulation.

Biochemistry international, 1984

The intestinal uptake rate of oxalate (mumoles/h/g tissue wt.) in castrated male (CM) rats, CM ra... more The intestinal uptake rate of oxalate (mumoles/h/g tissue wt.) in castrated male (CM) rats, CM rats administered estradiol, and female (F) rats was 1.8, 1.4 and 1.3 times higher than that of male rats, whereas castrated female (CF) rats and CF rats administered testosterone absorbed oxalate at a rate similar to F rats, thereby, suggesting that gonadectomy affected intestinal uptake of oxalate only in male rats The intestinal oxalate uptake rate in all the groups increased linearly with increasing oxalate concentration (0.1- 6.0 mM). Chemical composition of brush border membrane showed significant changes in the sialic acid, phospholipid and cholesterol content following castration, which may lead to ultrastructural changes in the membrane thereby, increasing the absorption of oxalate.

Journal of Clinical Oncology

2530 Background: Virtually all cancer treatments that kill cancer cells also adversely affect nor... more 2530 Background: Virtually all cancer treatments that kill cancer cells also adversely affect normal cells and often have debilitating side effects. A key challenge has been to identify antigens that are suitable for antibody-based targeted therapeutics. We have developed a novel platform to detect and identify multiple cell surface antigens that are unique to human cancers. Methods: Breast Cancer cells (Hs578T) or Melanoma cells (Hs895.T) were injected into rabbits to generate polyclonal xeno-antibodies. The resulting serum against each cancer was then incubated with normal cells of the same tissue type derived from the same patients; Breast Epithelium (matched-pair Hs578Bst) or Skin Fibroblasts (matched-pair Hs895.Sk) in order to absorb antibodies that cross-react with antigens on normal tissue (U.S. Patent Application No. 16/243,161). Flow cytometry was used for measuring the binding capacity of the unfiltered serum and filtered serum (lacking cross-reacting antibodies) on both t...

Bba Biomembranes, 1987

Two kinds of membrane (luminal and abluminal membrane domains) fractions have been isolated from ... more Two kinds of membrane (luminal and abluminal membrane domains) fractions have been isolated from bovine aortic endothelial cells by fractionation of whole cell homogenate on discontinuous sucrose density gradients. The luminal membrane domain was enriched 12-16-fold for angiotensin-converting enzyme activity and 8-10-fold in alkaline phosphatase activity. The abluminal membrane domain displayed an enrichment of 8-fold in (Na++ K+)-ATPase activity. Both of the membrane domains were minimally contaminated with mitochondria, microsomes and Goigi bodies, as assessed by their corresponding marker enzyme activities. 125I-labeling of endothelial cell monolayers by the Enzymo-Bead lactoperoxidase-catalyzed iodination procedure, followed by isolation of membranes, revealed that the radioactivity was predominantly associated with membranes enriched in angiotensin-converting enzyme activity, corresponding to the luminal membrane domain. However, when cells were radioiodinated in suspension culture, radioactivity was found equally associated in both the luminal and abluminal membrane fractions. Electron microscopy of freeze-fractured and sectioned material showed both luminal and abluminal membrane domains to be in the form of vesicles varying in size from 100 to 400 nm in diameter. To characterize the separation of endothelial cell membrane domains, we have attempted to prepare monoclonal antibodies specific for endothelial cells. Several clones were obtained, producing antibodies which bound to endothelial cells of arterial, venous and capillary origin. Two antibodies of these clones, XIVC 6 and XVD2, were studied in more detail. In the ELISA assay, these antibodies reacted with bovine vascular endothelial cells, but not with human umbilical cord endothelial cells, nor with bovine corneal endothelial cells, smooth muscle cells or flbroblasts. Both of these antibodies are directed against an antigen of approximately 130 kDa, under reducing and non-reducing conditions, as assayed by the immunoprecipitation method. Western blot analysis of luminal and abluminal membrane fractions revealed that only MAb XVD 2 reacted with an antigen, indicating that the antibody XIVC 6 is directed against an epitope which is denatured by SDS. Moreover, Abbreviations: BAEC, bovine aortic endothelial cells; GAM-FITC, goat antimouse Ig, fluorescein isothiocyanate (FITC) conjugated; ELISA, enzyme-linked immunosorbent assay.

J Neurochem, 2002

In a previous study, it was observed that the activity of rolipram-sensitive, low-Km, cyclic AMP ... more In a previous study, it was observed that the activity of rolipram-sensitive, low-Km, cyclic AMP phosphodiesterase (PDE4) was decreased in vivo with diminished noradrenergic stimulation. The results of the present experiments indicated that the reduction in the activity may be associated with down-regulation of PDE4 protein. Immunoblot analysis using PDE4-specific, subfamily-nonspecific antibody (K116) revealed four major bands of PDE4 in rat cerebral cortex; those with apparent molecular masses of 109 and 102 kDa are variants of PDE4A. Diminished noradrenergic activity, produced by intracerebroventricular infusion of 6-hydroxydopamine (6-OHDA) or chronic subcutaneous infusion of propranolol, decreased the intensities of the protein bands for the 109- and 102-kDa PDE4A variants in rat cerebral cortex but not of the 98- or 91-kDa PDE4 forms. 6-OHDA-induced noradrenergic lesioning also decreased the content of 102-kDa PDE4A in hippocampus as labeled by PDE4A-specific antibody (C-PDE4A). Enhanced noradrenergic stimulation up-regulated PDE4 in cerebral cortex. This was indicated by the finding that repeated treatment with desipramine increased the intensity of the protein band for the 102-kDa PDE4 but not for the other variants of PDE4. These results suggest that PDE4 subtypes are differentially regulated at the level of expression, as evidenced by an apparent change in the amount of PDE4 protein, following changes in noradrenergic activity. These observations are consistent with the notion that PDE4s, especially the PDE4A variants with molecular masses of 109 and 102 kDa, play an important role in maintaining the homeostasis of the noradrenergic signal transduction system in the brain and may be involved in the mediation of antidepressant activity.

Brain Research, May 1, 1992

The precise distribution of the dopamine type D2 receptor has been mapped for the first time in r... more The precise distribution of the dopamine type D2 receptor has been mapped for the first time in rat brain using an antibody to D2 receptor protein. Polyclonal antisera were collected from rabbits inoculated with an undecapeptide identical to residues 24-34 of the D2 protein sequence. Rat brain slices, 40 microns in thickness, were incubated with either primary antiserum, the antiserum plus free peptide antigen, or pre-immune serum. Antibody binding was visualized by peroxidase-antiperoxidase (PAP) reaction followed by light microscopy. PAP complex bound moderately-to-densely throughout the medial forebrain bundle, and was seen in more discrete regions in the midbrain, consistent with the binding of D2 radioligands. There were some unexpected results, namely in the cerebral cortex and nucleus accumbens, there were unexpectedly steep gradients in binding density, decreasing caudally; no binding was detected in the hippocampus or the substantia nigra pars reticulata. In all positive-staining regions examined, the antibody was highly localized to neuronal cell bodies, except in the frontal cortex where antibody was also evident on basilar dendrites. These data confirm that the polyclonal antibody recognized dopamine D2 receptor protein throughout the rat brain, and suggest that the D2 receptor is distributed more abundantly on somata than on cellular processes.