Biomedical subjects

P Srivastava

Publications and source records attributed to P Srivastava.

At least 19 recordsLinked to original sources

PubMed2006

Effect of farmyard manure application on boron adsorption-desorption characteristics of some soils.

Boron (B) availability to crop plants depends on soil properties as well as management practices like liming, fertilization and use of organic manures. To assess the effect of farmyard manure (FYM) application on availability of added B, adsorption-desorption of B was investigated in five different soils receiving varying doses of FYM (0, 5 and 10 g FYM kg(-1) soil). Two surfaces Freundlich model was found best to account for B adsorption-desorption data of all soils. Application of FYM increased B adsorption capacities pertaining to low (K1) and high (K2) concentration ranges in all soils, except Soil C (Alfisol) having a pH of 9.8, in which the higher rate of FYM decreased the value of K2. Application of FYM did not change B desorption capacities of soils corresponding to low B concentration range (K(1)(1)) significantly, however, it increased B desorption capacity pertaining to high B concentration (K(1)(2)) in all soils, except Soils C (Alfisol) and E (Entisol) having pH of 9.8 and 5.1, respectively. Application of FYM increased the desorption slope factor applicable to low concentration range (1/n(1)(1)) in Soil A (Inceptisol), but decreased it in Soil E (Entisol). The 1/n(1)(2) (desorption slope factor applicable to high concentration range) decreased with FYM application in all soils except Soil E (Entisol), where it was increased. Boron desorption index (slope(ads)/slope(des)) decreased with FYM application in low B concentration range, but increased in high concentration range for all soils except soil E (Entisol, pH 5.1), in which a reverse trend was observed. Application of FYM increased the retention of added B in soils and may help reducing the leaching losses.

Adsorption↗

PubMed2006

Role of azathioprine in preventing recurrences in a patient of recurrent erythema nodosum leprosum.

The pathogenesis of erythema nodosum leprosum (ENL) involves both immune complex deposition and dysfunction of cell mediated immunity. Tumour necrosis factor-alpha (TNF-alpha) plays an important role in its pathogenesis. Thalidomide and corticosteroids are the mainstay of treatment for ENL. However, there are often severe limitations to their use. We report a case of recurrent ENL treated successfully with azathioprine. A 15-year-old unmarried girl with lepromatous leprosy had recurrent ENL for 2 years. She was treated with WHO-MB MDT and prednisolone in doses of 40-90 mg a day for 2-12 weeks. Her condition was inadequately controlled. The patient was therefore treated with thalidomide 300 mg and prednisolone 40 mg. The symptoms subsided after 5 days and ENL lesions healed in 2 weeks. Prednisolone was reduced by 10 mg per week and stopped, while thalidomide was reduced to 100 twice daily after 4 weeks. Azathioprine 100 mg (2 mg/kg per day) daily orally was added to prevent recurrences. Thalidomide was further reduced and stopped after another 4 weeks while she continued with azathioprine in the same doses for 8 months. There was no recurrence of ENL lesions and no side effects of the therapy. MB-MDT was stopped 1 year ago, and she is on follow-up without any relapse. Azathioprine, therefore, appears to be an effective and safe drug to prevent recurrences of ENL.

Administration, Oral↗

PubMed2005

Therapeutic modulation of allergic airways disease with leukotriene receptor antagonists.

Although asthma is one of the most common chronic respiratory conditions, it often remains unrecognized and undertreated, while patients are often reluctant to comply with regular inhaled anti-inflammatory and bronchodilator therapy. Allergic rhinitis co-exists with asthma in as many as 40% of patients, and can be regarded as a continuum of the same inflammatory disease process. Corticosteroids are the 'gold standard' first-line treatment for both conditions, and have a significant impact upon underlying inflammation, symptoms and long-term outcome. Cysteinyl leukotrienes are potent airway inflammatory mediators, suggesting that treatment antagonizing their effects could play a role in disease management. In recent years, leukotriene receptor antagonists have provided a further therapeutic option in the management of allergic airways disease. These drugs are orally active, can be administered once daily, and provide a systemic approach to the management of patients with asthma and allergic rhinitis. We review the pharmacology of leukotriene receptor antagonists, their potential role in clinical practice in patients with allergic airways disease, and likely areas for further research.

Adrenergic beta-Agonists↗

PubMed2004

The heat-shock protein receptors: some answers and more questions.

The existence of heat-shock protein (HSP) receptors on antigen-presenting cells (APCs) was hypothesized in 1994. The first such receptor, CD91 or LRP, was identified and characterized in 2000. The pace of attribution has quickened since and during the last three years alone, six putative HSP receptors have been identified. These include CD40, LOX-1, CD36, Toll-like receptor-2 (TLR-2), TLR-4 and SR-A. The literature on HSP receptors on APCs is critically examined in this review and future directions are imagined.

Animals↗

PubMed2003

Optical properties of Dy3+ doped calibo glass on addition of lead oxide.

The effects of PbO on optical properties of dysprosium doped calibo glass have been studied. The content of PbO in the glass has been varied from 0 to 60 mol%. The absorption and fluorescence spectra are analyzed in terms of the Judd-Ofelt theory. It is observed that the fluorescence yield is maximum for the glass containing 40 mol% PbO. The I-R absorption spectra of these glasses have also been recorded and interpreted in terms of changes in the structure of the glasses.

Dysprosium↗

PubMed2003

Association of CCR5Delta32 with reduced risk of childhood but not adult asthma.

BACKGROUND: A number of potential candidate genes have been implicated in the pathogenesis of asthma. A 32 base pair deletion in the CCR5 gene renders this chemokine receptor non-functioning and has been shown to be associated with a reduced prevalence of asthma in childhood. The mechanism may be related to impairment of pathogen entry into cells and modified host inflammatory response. We sought to determine the influence of the CCR5Delta32 mutation on asthma and allergy in the transition from childhood to adulthood. METHODS: 627 individuals first studied as part of a whole population schoolchildren cohort in 1989 when aged 8-12 years were followed up 10 years later for respiratory and allergy symptoms and laboratory markers of atopy. CCR5Delta32 status was also characterised and the association with childhood and adulthood symptoms determined. RESULTS: The follow up sample was representative of the original cohort except for a slightly greater prevalence of symptomatic individuals. As children, none who were homozygous for the CCR5Delta32 mutation had a current physician's diagnosis of asthma. In multivariate analysis and controlling for known confounders, the protective effect of carrying the allele in childhood was highly significant (OR 0.31, 95% CI 0.14 to 0.72, p=0.006). There was no protective association with "current asthma" as classified in adulthood within the same population. Subjective or laboratory markers of atopy in childhood or adulthood were not associated with the CCR5Delta32 mutation. Methacholine bronchial hyperresponsiveness in adulthood was also unrelated to gene carrier status. CONCLUSIONS: In a population with a high allelic frequency for the CCR5Delta32 mutation, a significant protection against childhood asthma is evident which is independent of atopy. This protection is lost in the transition between childhood and early adulthood. The contribution of different genetic candidates to the expression of asthma may change with advancing maturity and confound the interpretation of association and linkage studies unless age is taken into account.

Adult↗

PubMed2002

Role of endogenous reactive oxygen derived species and cyclooxygenase mediators in 5-hydroxytryptamine-induced contractions in rat aorta: relationship to nitric oxide.

Endogenous reactive oxygen species (superoxide anion, hydroxyl radical and hydrogen peroxide), endothelium-derived nitric oxide and cyclooxygenase mediators are involved in the regulation of vascular smooth muscle tone. An imbalance of these mediators can have profound implications in various cardiovascular disorders. Involvement of endogenous reactive oxygen species, endothelium-derived nitric oxide (NO) and cyclooxygenase mediators in 5-hydroxytryptamine- (5-HT-) induced contractions of endothelium intact rat aortic rings have been investigated in the present study. The contribution of each of the endogenous reactive oxygen species in mediating 5-HT-induced contractions was studied by pretreating the rings with their respective scavengers. Pretreatment of the rings with superoxide dismutase (superoxide radical scavenger), catalase (H (2)O (2)inactivator), mannitol (extracellular OH. scavenger), or thiourea (intracellular OH. radical scavenger) significantly depressed the 5-HT-induced contractions in the aortic rings. The responses to 5-HT in the presence of SOD or catalase were augmented byL -NAME pretreatment. Though aminotriazole partially inhibited the catalase activity, it inhibited 5-HT-induced contractions significantly. The results obtained thus suggest that endogenous generation of ROS (O(2).(-), H (2)O (2)and OH.) modulates 5-HT-induced rat aortic ring contractions. In addition, H (2)O (2)generated in the endothelium seems to regulate the vascular response and also act as a mediator to release other vasoactive substances. Basal production of NO by the endothelium seems to affect the vascular response due to its interaction with ROS mediators.

Amitrole↗

PubMed2001

Primary tumor tissue lysates are enriched in heat shock proteins and induce the maturation of human dendritic cells.

Upon exposure to lysates or supernatants of necrotic transformed cell lines, human dendritic cells (DCs) undergo maturation. In contrast, DCs exposed to apoptotic transformed cell lines or necrotic lysates of primary cells remain immature. Analysis of supernatants of necrotic transformed cell lines showed them to be enriched in the heat shock proteins (hsp)70 and gp96, in contrast to supernatants of primary cells. Likewise, cells from a variety of primary human tumors contained considerably higher levels of hsp than their normal autologous tissue counterparts. Of the majority of human tumors enriched in hsps (hsp70 and/or gp96), their corresponding lysates matured DCs. The maturation effect of tumor cell lysates was abrogated by treatment with boiling, proteinase K, and geldanamycin, an inhibitor of hsps, suggesting that hsps rather than endotoxin or DNA were the responsible factors. Supporting this idea, highly purified, endotoxin-depleted hsp70, induced DC maturation similar to that seen with standard maturation stimuli LPS and monocyte conditioned medium. These results suggest that the maturation activity inherent within tumor cells and lines is mediated at least in part by hsps. The release of hsps in vivo as a result of cell injury should promote immunity through the maturation of resident DCs.

Apoptosis↗

PubMed2001

Carbanion-induced base-catalyzed synthesis of 1H-isothiochromenes, benzo[c]thiochromenes through ring-transformation reactions of 6-aryl-2H-pyran-2-ones.

An innovative approach to the one-pot synthesis of highly functionalized 3,4-dihydro-1H-isothiochromenes (3), 6H-benzo[c]thiochromenes (5, 6), 6H-benzo[c]chromenes (8), and 2,3-dihydro-1-benzothiophenes (10, 11) is delineated from the reaction of a suitably functionalized 6-aryl-3-carbomethoxy-4-methylthio-2H-pyran-2-one (1) and a carbanion generated from tetrahydrothiopyran-4-one, 4-thiochromanone, 4-chromanone, and tetrahydrothiophene-3-one through ring-transformation reactions.

Journal Article↗

PubMed2001

Altered contractions to endothelin-1, phenylephrine, potassium chloride and relaxations to acetylcholine at various stages of renal hypertension in the rat.

This study is aimed at investigating the contraction and relaxation responses in the thoracic and abdominal aortae at various stages of hypertension. Hypertension in the rats was produced by aortic banding and the responses in the abdominal and thoracic aortic rings were studied 2 and 8 weeks after aortic banding. Contractile responses to phenylephrine ( 10(-6)M), KCl (80 mM) or to endothelin-1 ( 10(-12)to 10(-6)M) and the relaxation responses to acetylcholine ( 10(-7)to 10(-5)M) were similar in the thoracic and abdominal rings of normotensive rats. The intact thoracic rings from 2 week aortic-banded hypertensive rats (ABHR) showed attenuated responses to all the contractile agents used. However, the relaxation to acetylcholine was not altered. In the rings from 8 week ABHR, the responses to contractile agents were not significantly altered but the acetylcholine-induced relaxations were significantly attenuated. The endothelial-derived relaxing factors might act to antagonize the vasoconstrictive responses during the onset of hypertension but might be disabled, as the endothelial dysfunction becomes predominant after 8 weeks of hypertension. The results thus suggest that the contractile and relaxant responses are differentially altered during different stages of hypertension.

Acetylcholine↗

PubMed2001

Intraperitoneal gas drain to reduce pain after laparoscopy: randomized masked trial.

OBJECTIVE: To determine whether a drain placed in the peritoneal cavity during laparoscopy is both a clinical and cost-effective method of reducing postoperative pain. METHODS: Two hundred twenty-five women undergoing diagnostic or minor operative laparoscopic procedures were recruited. Women were assigned to receive either an intraperitoneal gas drain or a dummy drain during surgery. Sample size to detect a two-point difference in visual analogue score was estimated at 158 subjects, with 79 in each arm. The patients and nursing staff were unaware of the position of the drain. A visual analogue score was used to assess pain preoperatively and at 4, 24, and 48 hours postoperatively. Data on the experience of nausea, frequency of vomiting, and site of pain were collected. The analgesic and antiemetic use was recorded. An economic evaluation of the analgesic use and the material costs for the two groups was performed. RESULTS: One hundred sixty-one complete sets of data (72%) were available for analysis. The two groups were well matched for age, parity, previous surgery, body mass index, volume of carbon dioxide used, and operative time. No significant differences were found between the two groups with regard to the overall pain scores preoperatively (8 versus 7) or at 4 (30 versus 34), 24 (40 versus 44), and 48 (26 versus 26) hours postoperatively, after adjusting for multiple point testing. On assessment at different sites, the dummy drain group experienced shoulder pain more frequently at 4 (19 of 79 versus 10 of 82, P =.05) and 48 (16 of 79 versus 7 of 82, P =.03) hours postoperatively compared with the drain group. The placebo group had a 33% greater usage of oral analgesia after discharge, but this was $2.50 cheaper than the use of an intraperitoneal drain. No statistically significant differences were found between the groups with regard to nausea and vomiting postoperatively. CONCLUSION: An intraperitoneal drain after minor gynecologic laparoscopy decreases the frequency of shoulder pain and reduces postoperative analgesia requirements. However, it is less cost-effective to reduce pain using an intraperitoneal gas drain than simple oral analgesia after minor gynecologic laparoscopy.

Adult↗

PubMed2001

Angiotensin receptor blockers and aldosterone antagonists in chronic heart failure.

Prognosis in congestive heart failure is directly linked to neurohormonal activation. Angiotensin II through the activation of the renin angiotensin aldosterone system has been the principal focus therapy over the last 2 decades. New agents that target selective blockade of the angiotensin II receptor have been introduced in clinical trials for the treatment of heart failure. Aldosterone has been identified as a critically important neurohormone with direct detrimental effects on the myocardium. Aldosterone antagonists have been used in clinical trials to improve mortality in patients with chronic heart failure.

Aldosterone↗

PubMed2001

Cloning, characterization, and expression of xylanase gene from Bacillus lyticus in Escherichia coli and Bacillus subtilis.

A genomic library of Bacillus lyticus was constructed in lambda GEM 11 vector and screened for the xylanase gene using Congo red plate assay. A 16-kb fragment containing the xylanase gene was obtained which was further subcloned using Mbo I partial digestion in an E. coli pUC 19 vector. A 1.3-kb sub-fragment was obtained which coded for a xylanase gene of Mr 23,650 Da. This fragment was sequenced and the homology was checked with known xylanases. The maximum homology was 97%, which was obtained with an endo xylanase gene from Bacillus species at the DNA level, while the translated sequence showed only one amino acid change from alanine to serine at position number 102. Expression was checked in E. coli, using the native promoter, and an extracellular activity of 5.25 U/mL was obtained. Cloning of the gene was done in Bacillus subtilis using a shuttle vector pHB 201, which resulted in increasing the basal level xylanase activity from 14.02 to 22.01 U/mL.

Bacillus↗

PubMed2000

Enhancement of mass transfer using colloidal liquid aphrons: measurement of mass transfer coefficients in liquid-liquid extraction.

Interphase mass transfer of a sparingly soluble solute is often the rate-limiting step in multiphase biocatalytic processes. Colloidal liquid aphrons (CLA) provide very large interfacial areas, and thus could enhance mass transfer in such processes. The aim of this study was to characterize mass transfer properties of CLA dispersions during transfer of heptanoic acid from water to limonene. The interfacial area per unit volume (a), film mass transfer coefficient (K(L)), and volumetric mass transfer coefficient (K(L)a) values were determined in a stirred-tank reactor. These results were used, along with a literature correlation, to estimate the mass transfer coefficient of the surfactant-stabilized shell surrounding the CLA. The very large increase in a provided by the CLA was only partially offset by a slight increase in the mass transfer resistance of the shell. As a result, the range of K(L)a values obtained using CLA was about an order of magnitude greater than that obtained using a conventional dispersion. The concentration of the aqueous-phase surfactant used to form the CLA strongly affected the Sauter mean diameter of the CLA; however, the concentration of the nonpolar-phase surfactant had little effect. These results suggest that CLA have considerable potential for multiphase biocatalytic applications.

Biotechnology↗

PubMed2000

A new class of potential chloroquine-resistance reversal agents for Plasmodia: syntheses and biological evaluation of 1-(3'-diethylaminopropyl)-3-(substituted phenylmethylene)pyrrolidines.

1-(3'-Diethylaminopropyl)-3-(substituted phenylmethylene)pyrrolidines were synthesized and evaluated for CQ-resistant reversal activity. In general the compounds of the series elicit better biological response than their phenylmethyl analogues. The most active compound 4b has been evaluated in vivo in detail, and the results are presented. The possible mode of action of the compounds of this series is by inhibition of the enzyme heme oxygenase, thereby increasing the levels of heme and hemozoin, which are lethal to the parasite.

Animals↗

PubMed2000

Layer-resolved magnetic moments in Ni/Pt multilayers

The magnetic moments in Ni/Pt multilayers are thoroughly studied by combining experimental and ab initio theoretical techniques. SQUID magnetometry probes the samples' magnetizations. X-ray magnetic circular dichroism separates the contribution of Ni and Pt and provides a layer-resolved magnetic moment profile for the whole system. The results are compared to band-structure calculations. Induced Pt magnetic moments localized mostly at the interface are revealed. No magnetically "dead" Ni layers are found. The magnetization per Ni volume is slightly enhanced compared to bulk NiPt alloys.

Journal Article↗

PubMed2000

A highly functionalized ferrocenylpyrazolo[2,3-a]pyridine.

The crystal structure of [2-(4-bromophenyl)-4-cyano-5-ferrocenylpyrazolo[2,3-a]pyridin-7-yl]acetonitrile, C(26)H(17)N(4)FeBr or [Fe(C(5)H(5))(C(21)H(12)BrN(4))], shows that the pyrazolopyridine ring system (PP), the bromophenyl ring (BP) and the cyclopentadiene ring (Cp) are nearly planar. The PP ring system is twisted out of the plane of the BP and Cp rings by about 20 degrees.

Journal Article↗

PubMed2000

Studies on hepatic mitochondrial cytochrome P-450 during Plasmodium yoelii infection and pyrimethamine treatment in mice.

Hepatic mitochondrial cytochrome P-450 and b(5) activities were significantly depressed, whereas heme and hemozoin were increased during Plasmodium yoelii infection. Type II, aniline-HCl binding efficacy and polyacrylamide gel electrophoretic profile also depicted impairment of cytochrome P-450 during infection. However, the above alterations were more pronounced in the infected hepatic mitochondria, compared to microsomes. Oral treatment of pyrimethamine (10 mg/kg body weightx4 days) to P. yoelii-infected mice brought the altered levels of mitochondrial and microsomal cytochrome P-450 and b(5) to almost normal, whereas heme and hemozoin levels remained unchanged.

Animals↗