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Biomedical subjects

J Singh

Publications and source records attributed to J Singh.

At least 73 records · Page 4Linked to original sources
PubMed2003

Hepatocurative and antioxidant profile of HP-1, a polyherbal phytomedicine.

HP-1 a herbal formulation comprising of Phyllanthus niruri and extracts of Terminalia belerica, Terminalia chebula, Phyllanthus emblica and Tinospora cordifolia has been evaluated for hepatoprotective activity against carbon tetrachloride (CCl4) induced toxicity. Results show that HP-1 reversed the leakage of lactate dehydrogenase (LDH) and glutamate pyruvate transaminase (GPT) and prevented the depletion of glutathione (GSH) levels in a primary monolayer culture of rat hepatocytes (in vitro). HP-1 attenuated the serum toxicity as manifested in elevated levels of transaminases (glutamate oxaloacetate transaminase (GOT), and GPT) The antioxidative enzymes in liver (catalase and superoxide dismutase (SOD)) were restored to normal values after the oral administration of HP-1. HP-1 suppressed the formation of the superoxide anion radical and reduced CCl4 mediated lipid peroxidation (LPO). Silymarin and antioxidants (ascorbic acid, beta-carotene and alpha-tocopherol) were used for comparison. The present study showed that HP-1 is a potential hepatoprotective formulation with an additional attribute of being anti-peroxidative.

Administration, Oral↗
PubMed2003

Effect of bioaccumulation of cadmium on biomass productivity, essential trace elements, chlorophyll biosynthesis, and macromolecules of wheat seedlings.

Soil contamination with heavy metals has become a worldwide problem, leading to losses in agricultural yield and hazardous human health effects as they enter the food chain. The present investigation was undertaken to examine the influence of cadmium (Cd2+) on the wheat (Triticum aestivum L.) plant. Cd2+ accumulation and distribution in 3-wk-old seedlings grown in nutrient medium containing varying concentrations of Cd2+ (control, 0.25, 0.50, 1.0, 2.5, and 5.0 mg/L) was monitored. The effect of varying Cd2+ concentrations up to 21 d on biomass productivity, plant growth, photosynthetic pigments, protein, amino acids, starch, soluble sugars, and essential nutrients uptake was studied in detail to explore the level up to which the plant can withstand the stress of heavy metal. Plants treated with 0.5, 1.0, 2.5, and 5.0 mg/L Cd2+ showed symptoms of heavy-metal toxicity as observed by various morphological parameters which were recorded with the growth of plants. The root, shoot-leaf length and the root, shoot-leaf biomass progressively decreased with increasing Cd2+ concentration in the nutrient medium. Cd2+ uptake and accumulation was found to be maximum during the initial growth period. Cd2+ also interfered with the nutrients uptake, especially calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe2+), zinc (Zn2+), and manganese (Mn2+) from the growth medium. Growth reduction and altered levels of major biochemical constituents such as chlorophyll, protein, free amino acids, starch, and soluble sugars that play a major role in plant metabolism were observed in response to varying concentrations of Cd2+ in the nutrient medium. In the present study, the effects of Cd2+ on growth, biomass productivity, mineral nutrients, chlorophyll biosynthesis, protein, free amino acid, starch, and soluble sugars in wheat plants was estimated to establish an overall picture of the Cd2+ toxicity at structural and functional levels.

Amino Acids↗
PubMed2003

Asparagus racemosus--an update.

Asparagus racemosus (Shatavari) is recommended in Ayurvedic texts for prevention and treatment of gastric ulcers, dyspepsia and as a galactogogue. A. racemosus has also been used successfully by some Ayurvedic practitioners for nervous disorders, inflammation, liver diseases and certain infectious diseases. However, no scientific proof justifying aforementioned uses of root extract of A. racemosus is available so far. Recently few reports are available demonstrating beneficial effects of alcoholic and water extracts of the root of A. racemosus in some clinical conditions and experimentally induced diseases, e.g. galactogogue effect, antihepatotoxic and immunomodulatory activities. The present article includes the detailed exploration of pharmacological properties of the root extract of A. racemosus reported so far.

Asparagus Plant↗
PubMed2002

McBurney's point: are we missing it?

A prospective study of 100 post-evacuation barium enemas was done. Films were centered at McBurney's point, with an opaque skin marker at that point. Analysis of these revealed that in only one case (1%) was the base of the appendix at McBurney's point. In 67% it was cephalic and in 32% it was caudal to this point. The limitations of McBurney's point as an anatomical landmark should be recognized. This needs to be highlighted in teaching anatomy, especially to surgical trainees. Planning and choice of surgical incisions should be based on an understanding of these anatomical variations since McBurney's original description was clinical rather than anatomical.

Adolescent↗
PubMed2002

Simple high-performance liquid chromatography method for the simultaneous determination of ketoconazole and piperine in rat plasma and hepatocyte culture.

Piperine, a major alkaloid of black and long peppers has been reported to act as bioavailability enhancer of several drugs by inhibiting drug metabolising enzymes and/or by increasing oral absorption. Ketoconazole is a well established potent inhibitor of CYP 3A4 and P-glycoprotein. A simple and rapid HPLC method has been developed for the simultaneous analysis of ketoconazole and piperine in rat plasma and hepatocyte culture. Analysis was performed using a Symmetry C18 column (150x4.6 mm, 5 microm) and isocratic elution with 25 mM KH2PO4 (pH 4.5)-acetonitrile (50:50) with a flow-rate of 1 ml/min. Photodiode array detection was used to simultaneously monitor piperine at 340 nm and ketoconazole at 231 nm in a single sample. Calibration plots in spiked plasma, hepatocytes and William's medium E were linear over the range studied (10-2000 ng for both drugs). The detection limits for piperine and ketoconazole are 2 and 4 ng, respectively, and the limits of quantitation are 10 and 12 ng, respectively. Intra- and inter-assay variations were less than 8%.

Alkaloids↗
PubMed2002

Plasma melatonin, pinealocyte morphology, and surface receptors/antigen expression on macrophages/microglia in the pineal gland following a high-altitude exposure.

The present study examined the effects of high-altitude exposure on the pineal gland, the main source of production of melatonin. It was surmised that hypoxia experienced at high altitude, caused by decreased oxygen tension in the ambient air, might lead to some structural alterations in the pineal gland and, hence, affect its melatonin production. Adult Wistar rats were exposed to an altitude of 8,000 m for 2 hr in an altitude chamber and then sacrificed at various time intervals after the exposure. Normal rats kept at ground level were used as controls. Blood samples were collected at various time intervals for measurement of plasma melatonin level, and the pineal glands from both groups were processed for electron microscopy and immunohistochemistry. The plasma melatonin level showed a steady increase following altitude exposure peaking at 7 days and returned to control levels thereafter. Between 1 and 4 days after altitude exposure, the mitochondrial number and lipid droplets in the pinealocytes appeared to be reduced compared with those in control rats. At 7 days, however, the mitochondrial numbers and lipid droplets were noticeably increased. At the same time interval, the expression of complement type 3 receptors and major histocompatibility class II antigens as detected with the antibodies OX-42 and OX-6, respectively, in macrophages/microglia was up-regulated compared with that in the control rats and those killed at earlier times. This was attributed to the increased serum melatonin after the altitude exposure. By 14 and 21 days, the ultrastructure of pinealocytes and immunoreactivity of macrophages/microglia were comparable with those in the control rats. We conclude from this study that an altitude exposure in rats leads to an increase in melatonin production, which returned to control levels with passage of time.

Altitude Sickness↗
PubMed2002

Upregulation of adrenocorticotrophic hormone in the corticotrophs and downregulation of surface receptors and antigens on the macrophages in the adenohypophysis following an exposure to high altitude.

Altitude exposures lead to the development of hypobaric hypoxia because of low oxygen tension in the ambient air. This study has shown the vigorous upregulation of adrenocorticotrophic hormone (ACTH) expression in corticotrophs of the pars distalis (adenohypophysis) of rats 1-7 days after an altitude exposure. Concomitant to this was the increase in number and hypertrophy of the immunoreactive corticotrophs. It was suggested that this had resulted in an upsurge of ACTH production which may have suppressed the immuno-expression of complement type 3 receptors and major histocompatibility complex class II antigens constitutively expressed by the parenchymal macrophages through paracrine action. Along with ACTH, altered levels of other hormones following such exposures may also contribute to suppression of antigen presenting function and phagocytic activity of macrophages. The effects of altitude (hypobaric hypoxia) exposure, however, were reversible as the above immunohistochemical changes returned to normal 21-28 days after the hypobaric hypoxic insult.

Adrenocorticotropic Hormone↗
PubMed2002

Comparison of the antisecretory and antiulcer activity of epidermal growth factor, urogastrone and transforming growth factor alpha and its derivative in rodents in vivo.

This study investigates the effects of epidermal growth factor (EGF), urogastrone (UG) and transforming growth factor-alpha (TGFalpha) and its derivative on dimaprit- and pentagastrin-induced gastric acid secretion and on acidified ethanol (AE)-evoked ulcer formation in anaesthetized rats. EGF, TGFalpha and UG administered subcutaneously (s.c.) 30 min before dimaprit inhibited gastric acid secretion. Against pentagastrin-stimulated secretion, TGFalpha inhibited, while EGF and UG potentiated, acid secretion dose-dependently. Intraduodenal (i.d.) administration of TGFalpha and UG had no effect, while EGF potentiated, both secretagogue-induced acid secretion in the same dosage schedule. Administration of either EGF, UG or TGFalpha i.v. bolus, in response to continuous infusion of dimaprit resulted in a significant (p < 0.05-p < 0.001) inhibition of acid secretion which was transient and returned to normal within 30-45 min for UG while it slowly returned to normal for EGF and TGFalpha. The truncated form of TGFa (amino acids 34-43) did not show any antisecretory effect when administered parenterally. Acidified ethanol produced gastric haemorrhagic lesions in the rat 1 h after oral administration. The gastric mucosal protective effects of TGFalpha, EGF and UG administered either orally or s.c. 30 min before the administration of AE were dose-dependent against this model of ulcer induction. Indomethacin (Indo), administered 15 min before AE to inhibit prostanoids biosynthesis, significantly (p < 0.001) reduced the cytoprotective effects of TGFalpha, EGF and UG and aggravated the ulcer index when administered s.c. The results show that PGs may be involved in mediating the protective effects of the three growth factors. Administration of NG-nitro-L argininemethylester (L-NAME) 15 min prior to TGFa, EGF and UG s.c. or orally, significantly (p < 0.001) decreased the degree of ulcer indices and was able to reduce the protective effects of TGFalpha, EGF and UG, thus including the role of NO in mediating the protective effects of these growth factors. In conclusion, these results have demonstrated that EGF, UG and TGFalpha have a short and reversible inhibitory effect on dimaprit-stimulated gastric acid secretion and each is effective parenterally but not orally. UG and EGF potentiated, while, TGFa inhibited pentagastrin-stimulated acid secretion. In addition, TGFalpha seems to lose its activity when it is truncated from the C terminus. The present study also suggests that EGF, UG and TGFalpha are equally effective against AE-induced gastric ulcer and bring about their cytoprotective action through their reduction of acid secretion and through PG and NO pathways.

Animals↗
PubMed2002

A comparative study on the activity of lansoprazole, omeprazole and PD-136450 on acidified ethanol- and indomethacin-induced gastric lesions in the rat.

1. The proton pump inhibitors lansoprazole (LP) and omeprazole (OP) and the cholecystokinin (CCK)-receptor antagonist PD-136450 (PD) provide a broad spectrum of activities in their ability to inhibit gastric acid secretion and protect the stomach against ulcerogens. In the present study, we investigated the protective effects of these compounds against gastric ulcers induced by acidified ethanol (AE) and indomethacin. 2. Both AE (60% ethanol in 150 mmol/L HCl, 1 mL/rat) and indomethacin (30 mg/kg) produced gastric haemorrhagic lesions in the rat 1 and 6 h after oral administration, respectively. 3. The gastric mucosal protective effects of LP (1-20 mg/kg), OP (0.5-10 mg/kg) and PD (1-20 mg/kg), administered either orally or subcutaneously (s.c.) 30 min before the administration of AE or indomethacin, were dose dependent against both models of ulcer induction. 4. To determine whether the cytoprotective effect of LP, OP and PD (each 10 mg/kg) was mediated by endogenous prostaglandins (PG), indomethacin (10 mg/kg, s.c.) was administered 15 min before AE to inhibit prostanoids biosynthesis. Indomethacin reduced the cytoprotective effects of OP, but not LP, administered either orally or s.c. Indomethacin reduced the cytoprotective effect of PD administered orally, although the effect was much less significant than when PD was administered s.c. The results exclude the role of PG in mediating the protective effects of LP, whereas the possibility exists for PG to have a role in mediating the protective effects of OP and PD. 5. To investigate the possible involvement of endogenous nitric oxide (NO) in the cytoprotective action of LP, OP and PD, we treated rats with a selective inhibitor of NO synthesis, namely NG-nitro-L-arginine methyl ester (L-NAME; 25 mg/kg, s.c.). Administration of L-NAME 15 min prior to LP, OP or PD (each 10 mg/kg) orally or s.c. and challenge with AE or indomethacin did not significantly increase the degree of the ulcer index and L-NAME was not able to antagonize the protective effects of LP, OP and PD, thus excluding the role of NO in mediating the protective effects of these drugs. However, the effects of PD in reducing the indomethacin-induced ulcer index were less significant in the presence than the absence of L-NAME (P < 0.05 vs P < 0.001, respectively), suggesting a role for NO. 6. In conclusion, the results of the present study suggest that LP and OP are equally effective against AE- as well as indomethacin-induced gastric ulcers and were more potent than PD in protecting the stomach against ulcer formation. Lansoprazole, OP and PD bring about their cytoprotective action through the reduction of acid secretion and some other unknown mechanisms. However, OP and PD may exert their cytoprotective action through PG and NO pathways.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2002

Regeneration of the mandibular condyle after unilateral condylectomy and myotomy of the masseter in lambs.

We investigated the degree of regeneration of the mandibular condyle after unilateral condylectomy and myotomy of the masseter in growing lambs. Four 10-week-old lambs had unilateral condylectomy and myotomy of the superficial layer of the masseter on the right side, and were killed 3 months later. The joints were examined radiologically and histologically. All joints showed poor regeneration of the condylar head. In the medial plane there was partial condylar and articular cartilage reformation, but in the lateral plane there was neither condylar nor cartilaginous reformation. The articular cartilage of the temporal bone was thicker in the medial plane and the disc was thicker in the central plane, than in unoperated joints. We conclude that unilateral condylectomy and myotomy of the masseter in the growing period results in poor regeneration of the condyle.

Animals↗
PubMed2002

Effect of extracellular magnesium on nerve-mediated and acetylcholine-evoked in vitro amylase release in rat parotid gland tissue.

In this study the effects of changes in extracellular magnesium ([Mg(2+)](o)) and calcium ([Ca(2+)](o)) concentrations on basal and on nerve-mediated and acetylcholine (ACh)-evoked in vitro amylase release and calcium mobilization were investigated in rat parotid gland tissue. In the presence of a normal (2.56 mM) [Ca(2+)](o), both zero (0 mM) and an elevated (10 mM) [Mg(2+)](o) significantly attenuated basal and ACh-evoked amylase release compared to the response obtained in normal (1.1 mM) [Mg(2+)](o). During electrical field stimulation (EFS) of parotid tissues, only elevated [Mg(2+)](o) reduced amylase release. In a Ca(2+)-free medium, both basal and ACh-evoked amylase output were markedly reduced compared to the responses obtained under similar conditions in normal [Ca(2+)](o). Again, the ACh-induced amylase release in a Ca(2+)-free solution was larger in normal [Mg(2+)](o) than when the [Mg(2+)](o) was either zero or was elevated to 10 mM. Perturbation of [Mg(2+)](o) had no significant effect on basal intracellular free calcium concentration ([Ca(2+)](i)) in parotid acinar cells loaded with the fluorescent Ca(2+) indicator fura-2. Both zero Mg(2+) and an elevated [Mg(2+)](o) significantly reduced the ACh-induced rise in the peak and the plateau phase of the Ca(2+) transient that was seen in normal [Mg(2+)](o). In parotid acinar cells loaded with the fluorescent Mg(2+) indicator magfura-2, ACh elicited a gradual decrease in intracellular free Mg(2+) concentration ([Mg(2+)](i)) to below the basal level. The results indicate that both hypo- and hypermagnesaemia may reduce both basal and ACh-evoked amylase secretion from the salivary gland. As far as the ACh-evoked response is concerned, the effect may be exerted by a decrease in cellular Ca(2+) transport.

Acetylcholine↗
PubMed2002

Ispaghula husk.

Explore the source record for details and available documents.

Cathartics↗
PubMed2002

A study of cardiovascular effects of Azadirachta indica (neem) on isolated perfused heart preparations.

The effects of aqueous leaf extract of Azadirachta indica were evaluated on isolated prefused frog and rabbit heart. Dose dependent negative inotropic and chronotropic effects were observed in both the heart preparation. An increase in coronary blood flow in isolated rabbit heart was observed. The effects were not blocked by atropine and mepyramine in both the preparations. The data suggests that A. indica could be of benefit in coronary artery disease and arrhythmias.

Animals↗
PubMed2002

Immunoreactive insulin response to a single dose of glimepiride in lean type 2 diabetic subjects.

BACKGROUND: The best method for glucose lowering in lean type 2 diabetes remains controversial and this study was undertaken to study the 24 hour insulin response of these diabetics to glimepiride, a sulfonylurea with distinctive properties. METHODS: Twenty five consecutive newly diagnosed diet-unresponsive lean type 2 diabetics (BMI < 19 kg/m2) without any vascular complications were given single dose (1 mg) of glimepiride and insulin responses were measured 2,4,8,12 and 24 hours later. Pre and post-glimepiride blood glucose levels were also measured. RESULTS: All the post-glimepiride insulin levels were significantly higher than basal values. Increase in insulin secretion peaked at four hours and benefits lasted for at least 24 hours. This was accompanied by clinically and statistically significant reductions in fasting and postprandial blood glucose levels. Maximum secretory response correlated positively with beta cell function (HOMA) and negatively with fasting glucose. CONCLUSIONS: Glimepiride improved insulin secretion and hyperglycemia in lean type 2 diabetic subjects, with benefits lasting for 24 hours. The degree of response was proportional to the beta cell reserve, and occurred irrespective of the presence or absence of markers of insulin resistance.

Adult↗
PubMed2001

Effect of additives on the release of a model protein from PLGA microspheres.

The purpose of this study was to investigate the effect of 2 additives, poly(ethylene glycol) (PEG) 1000 and 1,2,3-tridecanoyl glycerol (tricaprin), on the physico-chemical characteristics and in vitro release of a model protein, bovine serum albumin (BSA), form poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres. BSA-loaded microspheres were prepared by the double emulsion solvent evaporation method. Additives were incorporated into microspheres to modify the release of protein. The addition of PEG 1000 and tricaprin changed the surface characteristics of microspheres from smooth and nonporous to porous and dimpled, respectively. The in vitro release profiles showed that the additives significantly (P < 0.05) increased the early-stage release of BSA from microspheres.

Delayed-Action Preparations↗