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Biomedical subjects

S Gupta

Publications and source records attributed to S Gupta.

At least 631 records · Page 35Linked to original sources
PubMed1998

Effects of antimony on rats following 90-day exposure via drinking water.

The subchronic toxicity of antimony in drinking water was studied in the rat. Male and female Sprague-Dawley rats (127-135 g body weight, 15 animals per group) were exposed to a soluble trivalent antimony salt, potassium antimony tartrate, in drinking water at concentrations of 0.5, 5, 50 and 500 ppm for 13 wk. Control rats received tap water as drinking water. An additional 10 male and 10 female rats were included in each of the control and 500 ppm groups and were given tap water for a further 4-wk recovery period after the 13-week treatment period. During treatment, the highest dose animals of both sexes consumed significantly less water and showed suppressed body weight gain. During recovery, water intake was quickly restored to that of the control groups and body weight gain was accelerated. At termination, one highest dose male had a cirrhotic liver, and three highest dose males exhibited gross haematuria. Female rats showed a dose-related decrease in serum glucose starting at 5 ppm, and rats of both sexes in the highest dose group had slightly decreased alkaline phosphatase activity and creatinine. The highest dose males had decreased red blood cell and platelet counts and increased mean corpuscular volume. Hepatic glutathione S-transferase activity was increased in the highest dose males and females and ethoxyresorufin-O-deethylase activity was increased in the highest dose males. In the highest dose groups, mild adaptive histological changes were observed in the thyroid, liver and pituitary gland of both sexes, and in the spleen of male rats and thymus of female rats. After a 4-wk recovery period, the pituitary gland of both sexes appeared normal and the changes in the liver and thyroid of both sexes became less severe. On the other hand, minimal changes persisted in the spleen of both sexes and in the thymus of males. Tissue antimony levels were dose-related and follow the order: red blood cells > > spleen, liver > kidney > brain, fat > serum. After the recovery period, antimony level in the highest dose animals decreased for all tissues except the spleen, which remained the same as before recovery. A NOAEL of 0.5 ppm antimony in drinking water, equivalent to an average intake of 0.06 mg/kg body weight/day, was established on the basis of the histological and biochemical changes observed at 5.0 ppm.

Animals↗
PubMed1998

Impact of intravascular ultrasound guidance in stent deployment on 6-month restenosis rate: a multicenter, randomized study comparing two strategies--with and without intravascular ultrasound guidance. RESIST Study Group. REStenosis after Ivus guided STenting.

OBJECTIVES: We aimed to investigate the impact of intravascular ultrasound (IVUS)-guided stent implantation on the 6-month restenosis rate, which has not yet been fully established in randomized trials. BACKGROUND: The 6-month angiographic restenosis rate was compared in patients with symptomatic ischemic heart disease who were randomly allocated to angioplasty and stent deployment, with versus without IVUS guidance. METHODS: After successful stent implantation, patients were randomized into two groups: Group A had no further dilation, and Group B had additional balloon dilation until achievement of IVUS criterion for stent expansion. The study group consisted of 164 patients, assuming a 50% reduction of the restenosis rate in Group B (15% vs. 30%) (alpha = 10%, beta = 20%). RESULTS: We enrolled 155 patients. Overdilation was carried out in 31 (39%) of 79 Group B patients, with the IVUS criterion being achieved in 63 (80%) of 79. No significant difference was observed in the minimal luminal diameter (MLD), but the stent lumen cross-sectional area (CSA) was significantly larger in Group B (mean +/- SD) (7.16 +/- 2.48 vs. 7.95 +/- 2.21 mm2, p = 0.04). At 6 months, there was no significant difference in the restenosis rate, (28.8% [21 of 73] in Group A vs. 22.5% [16 of 71] in Group B, p = 0.25), but according to the observed difference in the restenosis rate, the power of the study was only 40%. The difference in MLD was also nonsignificant (1.60 +/- 0.65 mm in Group A vs. 1.70 +/- 0.64 mm in Group B, p = 0.20), whereas the lumen CSA was 20% larger in the IVUS-guided group (4.47 +/- 2.59 vs. 5.36 +/- 2.81 mm2, p = 0.03). Lumen CSA was the only predictor of restenosis by multivariate logistic regression analysis. CONCLUSIONS: A nonsignificant 6.3% absolute reduction in the restenosis rate and a nonsignificant difference in MLD were observed in this study. Nonetheless, we still cannot rule out a beneficial effect of IVUS guidance, although this may have gone undetected owing to a lack of statistical power. A significant increase was observed in immediate and 6-month lumen size, as detected by IVUS, indicating that ultrasound guidance in stent deployment may be beneficial.

Angioplasty, Balloon, Coronary↗
PubMed1998

Intrapartum management of a patient with urticaria pigmentosa.

Urticaria pigmentosa is a cutaneous variant of mastocytosis. This is a complex group of diseases distinguished by abnormal aggregation of mast cells within the skin and other organs. Mast cell degranulation and subsequent release of vasoactive amines may occur in response to a variety of non-immune triggers leading to, as its most severe manifestation, a clinical picture of anaphylactic shock. We present the anaesthetic management during labour of a patient with urticaria pigmentosa.

Journal Article↗
PubMed1998

Role of transcutaneous ultrasound in evaluation of graft patency following minimally invasive coronary surgery.

OBJECTIVE: Recent development in minimally invasive coronary surgery prompted us to carry out prospective evaluation of patients undergoing coronary artery bypass grafting through left anterior small thoracotomy. METHODS: Between April 1996 and February 1997, 15 patients (age 32-70, 12 male) were operated on. The left internal thoracic artery (LITA) basal flow was assessed by means of transcutaneous Duplex ultrasound scanning with pulsed waved Doppler. Eight patients were studied in the immediate postoperative period (2-4 days) and seven patients (1-7 months) following revascularisation. In addition to that, nine patients underwent coronary angiography. RESULTS: LITA graft flows were quantifiable in all 15 patients. In two patients there was a significant reduction in both time-averaged velocity and total flow. The subsequent coronary angiogram revealed severe (>50%) stenosis of LITA graft in both patients. One of these patients had a reversible obstruction documented by Duplex scanning and coronary angiography. Systolic measures did not differ between normal (13) and stenosed grafts (2), but diastolic time-averaged velocity (indicating coronary run-off) and total flow appeared lower in the latter. CONCLUSIONS: LITA flow following left anterior small thoracotomy surgery can be evaluated non-invasively. Measurement of diastolic flow (i.e. coronary perfusion rather than internal thoracic branch run-off) and total flow is useful in estimating graft function.

Adult↗
PubMed1998

The effects of mating probability on the population genetics of nematodes.

We review how constraints on the mating probability of female worms by segregation within individual host guts form a critical element in the parasite population structure of nematodes. We consider the effects of these constraints on the population genetics of nematodes under various assumptions regarding worm competition as reflected in the relationship between the abundance of a certain genotype within the gut and the probability of reproductive success. The consequences for the emergence of resistance to drugs and immunotherapy and implications for host-parasite coevolution are discussed. We also review evidence for genetic heterogeneity in parasite populations as a necessary prerequisite for the applicability of mating probability models designed to assess the population genetics of nematodes.

Animals↗
PubMed1998

Transmission-blocking effects of sera from malaria-exposed individuals on Plasmodium falciparum isolates from gametocyte carriers.

Sera from donors exposed to malaria were tested for their ability to block the transmission of isolates from Cameroonian Plasmodium falciparum gametocyte carriers. Sera were selected from amongst Cameroonian and Gambian donors who had positive antibody reactivity against the surface of activated gametes and against epitopes of Pfs 48/45 (a potential transmission-blocking vaccine candidate antigen). Aliquots of washed blood from gametocyte carriers were resuspended in test and control sera and fed to An. gambiae mosquitoes via a membrane feeder. Comparisons of the prevalence and intensity of infections is dissected mosquitoes showed variations in the ability of sera to block the transmission of the different isolates. Sera were identified that had little or no blocking effect on the transmission of isolates unless the isolate was poorly infectious. Some sera completely blocked the transmission of some isolates whilst having little or no effect on others. The observed variation in transmission-modulating activity may have implications for the development of a transmission-blocking vaccine.

Adolescent↗
PubMed1998

Covert fears, anxiety and depression in congenital heart disease.

UNLABELLED: This study compared anxiety, fears, depression and behavioural problems as occurring in children with congenital heart disease, comparing them with samples of normal children. It further considered the influence of maternal anxiety, as well as analyzing a subgroup of children with cyanotic forms of congenital heart disease to determine if they were at higher risk than acyanotic children for the problems identified. METHOD: We recruited 40 consecutive children with congenital heart disease without obvious psychosocial problems from the Cardiology clinic at the Alberta Children's Hospital. Of the 40 children, 39 families consented to have the children participate, of which 24 were cyanotic and 15 acyanotic. Children completed the revised versions of the Fear Survey Scale-Revised and the Child Manifest Anxiety Scale as well as the Child Depression Inventory. Mothers completed the Child Behaviour Checklist, and the State Trait Anxiety Scale. RESULTS: Children with congenital heart diseases demonstrated more medical fears, and more physiological anxiety, than the normative samples. More specifically, children with cyanotic forms of congenital heart disease demonstrated more fears of the unknown, physiological anxiety, depression, and delinquent behaviors than the acyanotic children with congenital heart disease. Mothers of the children with cyanotic forms of congenital heart disease scored higher on both the state and trait scales, with higher maternal anxiety correlating with higher anxiety, medical fears and behavioral problems in the child. CONCLUSION: In a clinical setting, children with congenital heart diseases who do not present with psychological adjustment problems are still at risk for covert physiological anxiety, medical fears, depression and behavioral problems. The children with cyanotic malformations represent a subgroup at higher risk for these problems, which may be further exacerbated by increased maternal anxiety.

Adult↗
PubMed1998

Comparison of the effects of potential parenteral vehicles for poorly water soluble anticancer drugs (organic cosolvents and cyclodextrin solutions) on cultured endothelial cells (HUV-EC).

The effect of dilution of parenteral vehicles (organic cosolvent and 0.1 M cyclodextrin solutions) on cultured endothelial cells (HUV-EC) were compared in vitro. Cell morphology was observed by phase contrast light microscopy and cell viability by measuring 3-[4, 5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) reduction or intracellular lactate dehydrogenase (LDH) activity and total protein. Disruption of the HUV-EC monolayer was observed at dilutions of 1 in 20 for the melphalan and PEP cosolvents, 1 in 100 for an investigational drug cosolvent, and 1 in 10 for 0.1 M dimethyl-beta-cyclodextrin. In comparison, 0.1 M SBE7M- and HP-beta-cyclodextrin caused only minor disruption at a 1 in 5 dilution. MTT reduction, intracellular LDH, and total protein were decreased following exposure to 1 in 10 dilution of the melphalan cosolvent. For other test solutions, intracellular LDH activity and total protein were measured, and reductions were observed following exposure to 1 in 10, 20, and 50 dilutions of the investigational drug cosolvent and 1 in 5 dilution of DM-beta-cyclodextrin (0.1 M). At a dilution of 1 in 10, no delayed toxicity was observed for cosolvents or cyclodextrin solutions. Hence, 0.1 M SBE7M- or HP-beta-cyclodextrin formulations may be less damaging to the venous endothelium at the site of injection than organic cosolvent formulations.

Antineoplastic Agents↗
PubMed1998

Expression of abscisic acid-responsive element-binding protein in salt-tolerant indica rice (Oryza sativa L. cv. Pokkali).

As the products of abiotic stress and ABA inducible genes are predicted to play an important role in the mechanism of salt tolerance, the expression of transcription factor that recognizes abscisic acid-responsive element (ABRE) is likely to be regulated when plants are exposed to abiotic stress. Northern analysis of total RNA from control and salt-treated 10-day-old Pokkali (salt tolerant) rice plants was performed to find out the level of transcripts homologous to wheat cDNA (GC19) for EmBP-1 (bZIP class factor), a transcription factor that recognizes ABRE. Salinity stress (72 h)-induced accumulation of two transcripts, of 2.0 kb (r2.0) and 1.5 kb (r1.5), in roots was detected. Both transcripts were detectable even after 6 h of salt or abscisic acid treatment, whereas sheath and lamina showed constitutive levels of r1.5 transcript. When 32P-labeled DNA containing ABRE was used in a gel mobility shift assay, a low level of complex formation by binding factor was detected from the nuclear extract of lamina of control rice plants. Quantitative enhancement of complex formation was found with the nuclear extract prepared from the lamina of plants treated with 200 mM NaCl for 26 h over control nuclear extract, suggesting a step of regulation of expression of ABRE-binding protein in response to salinity stress. South-western blot analysis of equal amounts of nuclear proteins of lamina showed binding of 32P-labeled ABRE-DNA with two polypeptides (22-28 kDa) present at constitutive levels in control or NaCl-treated plants. Preincubation of the laminar nuclear extract of control plants, with spermidine or proline at 5 mM concentration showed quantitative enhancement of ABRE binding activity. Kinetics of spermidine stimulation showed gradual increase of complex formation from 5 mM concentration. Similarly, addition of GTP to the control nuclear extract also showed quantitative enhancement of complex formation and heparin was found to inhibit GTP activated complex formation by about 25%. Results may suggest the presence of ABRE binding protein in presynthesized and inactive form in control plants and GTP mediated activation is probably one of the way to regulate the expression of ABRE-binding factor.

Abscisic Acid↗
PubMed1998

Activation of vitellogenin II gene expression by steroid hormones in the old Japanese quail.

Alterations in the basal transcription rates of eukaryotic genes are believed to involve the binding of trans-acting factor(s) with specific DNA sequences in the promoter. We show here two interrelated events for the VTGII gene of the old, non-egg laying Japanese quail: alterations in the structure of the chromatin encompassing the gene, and binding of trans-acting factors to the promoter of the gene. Estradiol/progesterone alone or together cause alterations in the conformation of the chromatin of the promoter region of the gene. This may allow free access of nuclear protein(s) to the cis-acting elements, ERE, PRE and NF1, in the promoter of the gene and cause activation of transcription.

Aging↗
PubMed1998

Olanzapine augmentation of clozapine.

In clinical practice, patients are encountered who are partial responders or nonresponders to clozapine. There are others who are unable to tolerate a high dosage of clozapine. In the two cases presented, we propose an alternative strategy using olanzapine in combination with clozapine in treatment-refractory patients. Olanzapine was found to be helpful in these patients, however, controlled studies are needed.

Adult↗
PubMed1998

Risperidone-induced galactorrhea associated with a prolactin elevation.

We report on the occurrence of galactorrhea associated with a prolactin elevation within weeks of treatment with risperidone. One of our patients was switched to a typical antipsychotic, with an improvement in the galactorrhea. The other patient was continued on risperidone due to a robust response, while her galactorrhea was partially treated with bromocriptine. The mechanism of prolactin elevation with risperidone is unclear. These cases suggest the need for further studies.

Adult↗
PubMed1998

A possible role of multidrug resistance-associated protein (MRP) in basic fibroblast growth factor secretion by AIDS-associated Kaposi's sarcoma cells: a survival molecule?

Kaposi's sarcoma (KS) is considered a disorder of cytokines. Basic fibroblast growth factor (bFGF) is produced by AIDS-associated KS (AIDS-KS) cells and supports their growth in an autocrine and paracrine manner. bFGF lacks a signal sequence; therefore, its mechanism of secretion is unclear. In this study, we investigate the role of two important members of ATP-binding cassette transport proteins, the P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP), in the secretion of bFGF from AIDS-KS cells. Expression of P-gp and MRP was examined at both the protein and the mRNA levels by flow cytometry and RT-PCR respectively. Intracellular and secreted bFGF was measured by ELISA. AIDS-KS cells expressed MRP at both the mRNA and the protein levels; however, no P-gp expression was detected at either the mRNA or the protein level. Probenecid, a putative inhibitor of MRP efflux function, in a concentration-dependent manner, inhibited bFGF secretion, with a concomitant increase in intracellular bFGF, demonstrating that probenecid blocks bFGF secretion without inhibiting its synthesis. In addition, probenecid induced apoptosis in AIDS-KS cells. AIDS-KS cells expressed fas, bcl-2, and bcl-xL genes but lacked fasL and bax gene expression. These data suggest that bFGF is secreted from AIDS-KS cells via a probencid-sensitive transporter, most likely in MRP. Furthermore, probenecid appears to induce apoptosis in AIDS-KS cells by depriving them of the growth promoting activity of bFGF. These data suggest that MRP may play a role as a survival molecule in AIDS-KS cells.

AIDS-Related Opportunistic Infections↗
PubMed1998

The expression of functional postsynaptic alpha2-adrenoceptors in the corpus cavernosum smooth muscle.

1. The purpose of this study was to determine if corpus cavernosum smooth muscle expresses functional postsynaptic alpha2-adrenoceptors (AR). 2. The alpha2-adrenoceptor agonist UK 14,304 elicited concentration-dependent contractions in rabbit corpus cavernosum smooth muscle (CCSM). The half-maximal response occurred at 0.32+/-0.03 microM and the maximum contraction at 10 microM UK 14,304. 3. Pretreatment of CCSM strips with selective alpha2-adrenoceptor antagonists, rauwolscine and RS-15385, produced rightward shifts in the dose-response curves to UK 14,304 (pA2 values 7.1 and 8.5, respectively). In contrast, these antagonists did not alter contraction induced by the alpha1-adrenoceptor agonist phenylephrine (PE) or oxymetazoline. UK 14,304-induced contractions were also inhibited by prazosin (pA2 = 9.08). 4. UK 14,304-induced contractions, unlike those to PE, were highly dependent on the presence of extracellular Ca2+. 5. [3H]-rauwolscine bound to CCSM membranes with high affinity (Kd = 1.5 nM). [3H]-rauwolscine binding was displaced by unlabelled rauwolscine, RS-15385, UK 14,304 and prazosin, but not by PE. 6. UK 14,304 inhibited forskolin and prostaglandin E1 (PGE1)-induced increases in intracellular cyclic AMP concentration in primary cultures of rabbit CCSM cells. 7. These results demonstrate that CCSM expresses Gi-coupled postsynaptic alpha2-adrenoceptors, and activation of these receptors causes contraction of trabecular smooth muscle.

Adrenergic alpha-Agonists↗
PubMed1998

Cyclic AMP modulates TGF-beta 1-induced fibrillar collagen synthesis in cultured human corpus cavernosum smooth muscle cells.

INTRODUCTION AND OBJECTIVES: The mechanisms by which PGE1 suppresses transforming growth factor beta 1 (TGF-beta 1) induced fibrillar collagen synthesis in human corpus cavernosum smooth muscle cells (HCC SMC) remain undefined. Since PGE1 induces cyclic AMP (cAMP) synthesis in HCC SMC, the aim of this research is to investigate the role of cAMP in the regulation of connective tissue biosynthesis in human corporal smooth muscle cells in culture. MATERIALS AND METHODS: HCC SMC were incubated for 24 h in media containing [3H] proline with and without TGF-beta 1 in the presence or absence of agents which modulate cAMP or cGMP synthesis, or hydrolysis. Fibrillar collagen synthesis was determined by [3H]-proline incorporation into pepsin-resistant, trichloroacetic acid and precipitable protein. RESULTS: TGF-beta 1-induced collagen synthesis in HCC SMC was inhibited by receptor-mediated (PGE1) and non-receptor-mediated (forskolin) increases in cAMP synthesis, as well as the cell-permeable analog, dibutyryl cAMP. Sodium nitroprusside, a nitric oxide donor, and the cell-permeable analog, dibutyryl cGMP had no effect on TGF-beta 1-induced collagen synthesis. CONCLUSIONS: Cyclic AMP synthesis in HCC SMC inhibits TGF-beta 1-induced collagen synthesis. Agents which increase cAMP through specific G-protein-coupled receptors, direct stimulation of adenylate cyclase, or inhibition of phosphodiesterase activity could have beneficial effects as modulators of corpus cavernosum connective tissue biosynthesis.

Cells, Cultured↗
PubMed1998

Phentolamine mesylate relaxes penile corpus cavernosum tissue by adrenergic and non-adrenergic mechanisms.

AIM OF THE STUDY: We investigated the biochemical and physiological mechanisms of action of phentolamine mesylate (Vasomax) in regulating erectile tissue smooth muscle contractility in human and rabbit corpus cavernosum. METHODS: The binding activity of phentolamine was investigated in a cell-free system by displacement of specific and selective radiolabelled ligands to alpha 1 and 2 adrenergic receptors. The physiologic activity of phentolamine-mediated relaxation of adrenergic and non-adrenergic pre-contracted erectile tissue strips of human and rabbit corpus cavernosum were studied in organ bath chambers. RESULTS: In corpus cavernosum membranes, phentolamine displaced binding of the selective alpha 1 receptor antagonists [125I]HEAT and [3H]prazosin and the alpha 2 receptor antagonists [3H]rauwolscine and [3H]RX 821002 with relatively high affinity. Phentolamine caused concentration dependent relaxation in erectile tissue strips pre-contracted with adrenergic agonists phenylephrine, norepinephrine, oxymetazoline and UK 14,304, as well as with non-adrenergic contractile agents endothelin and KCl. Biochemical and physiologic studies reveal that the concentration of phentolamine required to displace half maximal binding or to produce half-maximal relaxation was similar to that found in human plasma 30 min after ingestion of 40 mg of Vasomax. Reversible inhibition of nitric oxide synthase by L-nitroarginine or mechanical disruption of endothelium diminished non-adrenergic phentolamine-mediated erectile tissue relaxation. CONCLUSIONS: Phentolamine mesylate induced relaxation of corpus cavernosum erectile tissue by direct antagonism of alpha 1 and 2 adrenergic receptors and by indirect functional antagonism via a non-adrenergic, endothelium-mediated mechanism suggesting nitric oxide synthase activation.

Adrenergic alpha-Agonists↗
PubMed1998

Increased spontaneous apoptosis in T lymphocytes in DiGeorge anomaly.

The aim of this study was to determine whether increased apoptosis in peripheral blood lymphocytes plays a role in T cell deficiency associated with DiGeorge anomaly. T cell subsets from a patient with DiGeorge anomaly were examined for the expression of Fas, FasL, Bcl-2 and Bcl-XL at the protein level with monoclonal antibodies, using dual-colour flow cytometry, and at the mRNA level in mononuclear cells by quantitative reverse transcriptase-polymerase chain reaction. In vitro spontaneous apoptosis was examined by propidium iodide staining and DNA fragmentation, using flow cytometry and gel electrophoresis, respectively. Fas and FasL expression, both at the level of protein and of mRNA, was increased, whereas Bcl-2 expression was decreased both at the level of protein and of mRNA. However, no difference in Bcl-XL expression was observed between the patient and an age-matched control. A significant proportion of both CD4+ and CD8+ T cells from the patients underwent spontaneous apoptosis, whereas almost no spontaneous apoptosis was observed in the age-matched control. These data suggest that spontaneous apoptosis in T lymphocytes, at least in part, may be responsible for T cell deficiency in DiGeorge anomaly.

Adolescent↗