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Biomedical subjects

G P Gupta

Publications and source records attributed to G P Gupta.

At least 19 recordsLinked to original sources
PubMed2005

Plant codon optimized cry genes of Bacillus thuringiensis can be expressed as soluble proteins in Escherichia coli BL21 Codon Plus strain as NusA-Cry protein fusions.

For optimal expression of delta-endotoxins from Bacillus thuringiensis in plants, preferential changes in the codon sequences, and reduction in overall AT content in the nucleotide sequence of the genes is important. Reports suggest that sequences with such modifications cannot be overexpressed in bacteria. We report here that the modified genes can be overexpressed in a strain of Escherichia coli carrying extra tRNA genes for some of the codons occurring at high frequency in plant genes and less preferred in E. coli. We also demonstrate that proteins when expressed as fusion products with NusA protein, are obtained as soluble fraction rather than in inclusion bodies. This allows easy and accurate LC50 analysis on insect pests.

Animals↗
PubMed2005

Identifying site-specific metastasis genes and functions.

Metastasis is a multistep and multifunctional biological cascade that is the final and most life-threatening stage of cancer progression. Understanding the biological underpinnings of this complex process is of extreme clinical relevance and requires unbiased and comprehensive biological scrutiny. In recent years, we have utilized a xenograft model of breast cancer metastasis to discover genes that mediate organ-specific patterns of metastatic colonization. Examination of transcriptomic data from cohorts of primary breast cancers revealed a subset of site-specific metastasis genes that are selected for early in tumor progression. High expression of these genes predicts the propensity for lung metastasis independently of several classic markers of poor prognosis. These genes fulfill dual functions-enhanced primary tumorigenicity and augmented organ-specific metastatic activity. Other metastasis genes fulfill functions specialized for the microenvironment of the metastatic site and are consequently not selected for in primary tumors. These findings improve our understanding of metastatic progression, facilitate the interpretation of primary tumor gene expression data, and open several important possibilities for future clinical application.

Animals↗
PubMed2001

Control of the buffalo fly Haematobia irritans exigua in India, using the pyrethroids deltamethrin and fenvalerate.

The effectiveness of two pyrethroids, fenvalerate and deltamethrin, against the fly Haematobia irritans exigua de Meijere (Diptera: Muscidae) on buffalo was considered in a field trial. Fenvalerate provided 100% control for 1, 2 and 4 weeks at concentrations of 0.03, 0.04 and 0.05%, respectively. Concentrations of 0.01 and 0.02% were less effective. One hundred percent control of this fly was obtained with deltamethrin for 2, 3 and 6 weeks at concentrations of 0.003, 0.004 and 0.005%, respectively. Deltamethrin concentrations of 0.001% and 0.002% achieved fly control for only 1-2 weeks, respectively.

Administration, Topical↗
PubMed1993

Diethylphenylacetamide: a new insect repellent against stable fly, Stomoxys calcitrans.

This paper reports the results of a laboratory study showing effectiveness of a new insect repellent N,N-diethylphenylacetamide (DEPA) against stable fly, Stomoxys calcitrans, and compared to N,N-diethyl-m-toluamide (DEET) and dimethyl-phthalate (DMP). DEPA gave maximum protection time of more than 6 h at 3% concentration followed by DEET and DMP.

Acetamides↗
PubMed1993

Serum sialic acid--an important cancer marker.

Total serum sialic acid (TSA), Lipid associated sialic acid (LASA), Total protein (TP) and TSA/TP factor (as cancer markers) have been estimated in 78 patients of cancer stomach, breast, colorectal region and gall bladder, before and after treatment and of varying degrees of metastasis and compared to 30 healthy controls. A significant rise in TSA and TSA/TP factor and a decrease in serum total protein levels was found in all cases of cancer. This increase was directly proportional to the degree of metastasis i.e. tumour burden. Serum TP levels were found decreased in all patients. Rise in LASA levels was not significant. Raised TSA/TP levels became lower to certain extent after effective therapy. Hence it can be inferred that although TSA and TSA/TP are not specific they are however, sensitive markers regarding detection of malignancy and useful in monitoring cancer progression and/or recurrent while evaluating the efficacy of various cancer therapies.

Adult↗
PubMed1991

Influence of chronic oral intake of cannabis extract on oxidative and hydrolytic metabolism of xenobiotics in rat.

Dietary intake of petroleum ether extract of cannabis leaves by rats in doses of 158, 250 and 500 mg/kg in the first, second and third week, respectively, caused selective induction of hepatic microsomal carboxylesterases/amidases without affecting the renal hydrolytic activity. Acetanilide N-deacetylase, p-nitrophenylacetate (NPA) esterase and acetylsalicylic acid (ASA) esterase I and II (active at pH 5.5 and 7.4) were stimulated 125, 64, 82 and 60%, respectively, whereas the activities of procaine esterase and acetylaminofluorene (AAF) N-deacetylase remained unaltered. The hydrolysis of acetylcholine was also unchanged. Upon withdrawal of treatment microsomal hydrolytic activity receded to basal levels within 7 days. Curiously though, the two-fold induction of thiacetazone N-deacetylase (118%), a cytosolic hydrolase, remained largely undiminished (62%). An appraisal of the hepatic cytochrome P450 mediated oxidative metabolism revealed approximately three-fold induction of aromatic hydrocarbon hydroxylase (AHH) metabolizing benzo(a)pyrene whereas the N-demethylation of aminopyrene was unaffected. These activities were restored to normal when resin administration was discontinued.

Amidohydrolases↗
PubMed1991

Protection against gastric ulcer by verapamil.

The effect of verapamil, a calcium channel blocker, was studied against stress (cold restraint), aspirin and pylorus ligation induced gastric ulcers in rats. Verapamil inhibited ulcerogenic response and ulcer index in all the three types of ulcers. Verapamil also decreased total and free gastric acidity without changing gastric secretory volume.

Animals↗
PubMed1991

Novel effects of MPTP: MAO-B unrelated opioidergic activity in mice.

The presence of opioidergic activity after i.p. injection of N-methyl-4-phenyl tetrahydropyridine (MPTP) has been investigated in albino mice by studying analgesia and the Straub reaction. MPTP (6.25-25 mg kg-1) produced a dose-related analgesic response and Straub reaction. These effects of MPTP were effectively antagonized by prior naloxone treatment but remained unaffected after the MAO-B inhibitor deprenyl. MPTP thus possesses significant opioidergic activity and this, unlike its neurotoxic actions, does not appear to be dependent on oxidative conversion to MPP+ (1-methyl-4-phenyl pyridinium).

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1991

Evidence for a central component in the cardiovascular effects of calcium channel blockers.

The possibility of a central component in the cardiovascular effects of peripherally administered calcium channel blockers has been explored through a comparison of the effects observed after intravenous (i.v.) and intracisternal (i.c.) administration of verapamil and diltiazem in chloralose-anesthetized and artificially ventilated cats. Both agents produced relatively greater effects after i.c. than after i.v. administration. The bradycardiac effect following i.c. as well as i.v. administration was totally abolished by bilateral cervical vagotomy, and the hypotensive effect was attenuated by this procedure. The results strongly suggest the existence of a central component in the cardiovascular effects of both agents.

Animals↗
PubMed1991

Control of the haematophagous fly Hippobosca maculata, a series pest of equines, by deltamethrin.

This study reports the results of both a small-scale and a large-scale field treatment to assess control of the haematophagous fly Hippobosca maculata Leach a serious pest of equines in a stud in India using a deltamethrin based formulation, Butox. In the small-scale field trial application of 2 litres of deltamethrin at 0.001-0.003% concentration gave 90-100% control over 30 days. At 0.004% and 0.005% concentrations complete control was recorded for 45 and 90 days respectively. Mass application of 2 litres of 0.005% deltamethrin to equines and bovines controlled infestations of H. maculata for 1 year.

Animals↗
PubMed1990

Anti-inflammatory activity of quinazolinoformazans.

Eight substituted quinazolonoformazans were synthesized and evaluated for anti-inflammatory activity. The degree of protection provided by seven of these compounds, at a dose of 100 mg/kg, po, against carrageenin-induced edema in rat paw ranged from 26 to 57%. The four active substituted quinazolonoformazans (1, 2, 6, 8), on further evaluation for antiwrithmogenic activity, provided 10-80% protection against the aconitine-induced writhing response in mice. The ulcerogenic liabilities of two of the most active compounds were also determined. The doses producing ulcers in 50% of the treated rats (UD50) were 155 and 260 mg/kg, ip, for 2 and 8, respectively. The low toxicities possessed by these substituted quinazolonoformazans were indicated by their LD50 values which ranged from 600 to 1300 mg/kg, ip, in mice.

Animals↗
PubMed1989

Role of histamine receptor in mesencephalic nucleus dorsalis raphe in cardiovascular regulation.

The effects of microinjection of histamine and its antagonists into mesencephalic nucleus dorsalis raphe, were investigated on mean arterial pressure and heart rate in cats to elucidate the nature and role of histaminergic receptors in cardiovascular regulation. Microinjection of histamine (5 and 10 micrograms) into nucleus dorsalis raphe elicited both inhibitory and excitatory cardiovascular responses respectively. On the other hand, microinjection of H2-receptor blocker, cimetidine (10 micrograms) resulted in hypertension and tachycardia while H1-receptor antagonist, mepyramine (10 micrograms) microinjection evoked hypotension and bradycardia. Furthermore, local pretreatment with cimetidine and mepyramine blocked the inhibitory and excitatory cardiovascular responses of graded doses of histamine microinjection. These H1 and H2 receptors are localized in nucleus dorsalis raphe since microinjection of histamine into adjoining neural structures did not evoke any cardiovascular change. Furthermore, both the inhibitory and excitatory cardiovascular responses to histamine microinjection could not be observed in animals with spinal cord transection and in animals pretreated with p-chlorophenylalanine while they could be observed in bilateral cervical vagotomized animals. Thus, it appears that these cardiovascular responses to microinjection of histamine into nucleus dorsalis raphe, are due to modulation of serotonergic bulbospinal influence on sympathetic preganglionic neurones in the spinal cord. Moreover, the excitatory cardiovascular responses of high dose of histamine (10 micrograms) seem to result from a local release of noradrenaline since they were blocked by prior microinjection of guanethidine and piperoxan into nucleus dorsalis raphe. A release of noradrenaline in turn, modulates the activity of the neurones of the nucleus by acting on alpha adrenoceptors and thereby alters the activity of sympathetic preganglionic neurones.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Control of haematophagous flies on equines with permethrin-impregnated eartags.

The efficacy of 10% (w/w) permethrin impregnated eartags for the control of the haematophagous fly pests Stomoxys calcitrans L., Haematopota dissimilis Meigen and Hippobosca maculata Leach on equines in India was determined. The tags were found to be effective for 1-2 months against S. calcitrans and H. dissimilis but completely ineffective against H. maculata. No tags were lost during the study. Tags can be used as part of an integrated control programme. This is the first reported use of eartags for control of haematophagous flies on horses.

Animals↗
PubMed1988

Role of central histaminergic mechanism in behavioural depression (swimming despair) in mice.

The role of the central histaminergic system in depression was studied by using swimming despair test in mice - a behavioural model of depression. In this test, immobility of mice reflects a state of depression. Intracerebral (ic) injection of histamine (50-200 micrograms) increased significantly the immobility. The H1-receptor blocker mepyramine (2.5-20 mg/kg ip) had no effect while H2-receptor blocker cimetidine (100-200 micrograms ic) caused a significant decrease in immobility. The histamine induced facilitation was blocked completely by cimetidine and antidepressant drugs-imipramine and desipramine, but remained unaffected in mice pretreated with mepyramine or atropine. The H2 agonist impromidine (20-40 micrograms ic) also enhanced significantly, the immobility which was blocked by cimetidine and antidepressant drugs. It has been concluded that central H2-receptors facilitate depression and antidepressant drugs block central H2-receptors.

Animals↗
PubMed1988

A study of central neurotransmitter mechanisms in morphine-induced 'Straub reaction' in mice: role of central dopamine receptors.

1. The role of putative neurotransmitters was investigated in morphine-induced Straub reaction (SR) in albino mice. 2. Apomorphine (15 mg/kg) was also effective in inducing SR. However, in a smaller dose (0.2 mg/kg) it blocked SR induced by morphine. 3. Morphine-induced SR was potentiated by tranylcypromine, reserpine (acute effect), imipramine and L-dopa and blocked by reserpine (chronic effect), alpha-methyldopa, pimozide, chlorpromazine, haloperidol and metoclopramide. Prazosin and clonidine partially blocked morphine SR in high doses. 4. Propranolol, yohimbine, cyproheptadine and atropine were ineffective in blocking morphine SR. 5. The results indicate that morphine SR is mediated through release of DA in the CNS which excites central D2 receptors. Activation of central alpha 1-adrenoceptors might also play a minor role.

Animals↗