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P Bhargava

Publications and source records attributed to P Bhargava.

52 records · Page 3Linked to original sources
PubMed1992

DNA intervention in transcriptional activation.

Accurate initiation of eukaryotic mRNA synthesis takes place as a result of the interplay between general transcription factors and RNA polymerase II. Activation of transcription from the basal level involves a number of promoter-specific trans-acting factors which interact with cis elements in the promoter DNA. In this paper we have emphasized the importance of even those portions of the promoter stretch which do not have any identifiable binding sites for regulatory proteins. The length and structure of the DNA between cognate binding sites of trans-acting factors may interfere with the level of transcriptional activation. Depending upon the length of the intervening DNA we describe three cases of transcriptional activation. In addition, based on this classification we propose a new third domain, the other two being DNA binding and transcriptional activation domains, which is involved in bending the intervening DNA so that activation from a distance can take place successfully.

DNA↗
PubMed1990

Magnesium induced activation of endogenous nucleases from isolated yeast nuclei: liberation of chromatin fragments of mono- and oligo- nucleosome size.

Isolated yeast nuclei were subjected to autodigestion by Mg2(+)-activated endogenous nucleases. The nuclear digests were analysed for their chromatin components. Gel electrophoresis and melting temperature analyses revealed the presence of DNA organized into nucleosomes. Our results demonstrate that magnesium activated endogenous endonucleases of yeast digest the chromatin into mono- and oligo- nucleosomal size fragments.

Cell Nucleus↗
PubMed1988

Spectroscopic studies on the mode of binding of ATP, UTP and alpha-amanitin with yeast RNA polymerase II.

The binding affinity between the substrates ATP and UTP with the purified yeast RNA polymerase II have been studied here in the presence and absence of Mn2+. In the absence of template DNA, both ATP and UTP showed tight binding with the enzyme without preference for any specific nucleotide, unlike Escherichia coli RNA polymerase. Fluorescence titration of the tryptophan emission of the enzyme by nucleoside triphosphate substrates gave an estimated Kd value around 65 microM in the absence of Mn2+ whereas in the presence of Mn2+, the Kd was 20 microM. The effect of substrates on the longitudinal relaxation of the HDO proton in enzyme-substrate complex also yielded a similar Kd value.

Adenosine Triphosphate↗
PubMed1987

DNA bound RNA polymerase activity of the yeast nuclei.

A preparation of nuclei from yeast cells is shown to be capable of autodigesting its chromatin in the presence of a series of magnesium containing buffers having different concentrations of potassium. The 'digests' or 'extracts' prepared in this manner contain an active transcription complex which can transcribe endogenous as well as exogenous DNA template. The effects of heparin and actinomycin D on the in vitro transcription by these complexes confirm the presence of RNA polymerase in DNA bound form. Further purification of this transcription complex is attempted by sucrose density gradient centrifugation. Circular dichroic measurements show that the nuclear DNA exists in compact state in the extracts.

Cell Nucleus↗
PubMed1984

Total gangliosides, ganglioside species and the activity of neuraminidase in different brain regions and spinal cord of normal and undernourished rats.

Total gangliosides, their concentrations and the distribution of individual ganglioside species were determined in the spinal cord, pons-medulla, midbrain, cerebellum, hypothalamus, cerebral cortex, olfactory lobes and the rest of the forebrain, of 18- and 33-day-old normal and food-restricted and rehabilitated rats. The activity of neuraminidase in the different regions of the brain and spinal cord was determined. Differences in total gangliosides as well as individual species in different regions of the brain were observed. Among brain regions, while total ganglioside content was significantly reduced in the case of the cerebellum, the hypothalamus was the most affected in the distribution of ganglioside species and the activity of neuraminidase was decreased. The significance of the distribution of ganglioside species in different brain regions in relation to the activity of neuraminidase is discussed.

Animals↗
PubMed1981

Modification by strychnine and D-tubocurarine of cardiac vagal inhibition in dogs.

Intravenous infusion of strychnine or D-tubocurarine chloride attenuated the cardiac depressant action and fall in blood pressure produced by electrical stimulation of the right vagus nerve in dogs anesthesized with pentobarbitone sodium. The effects of exogenous acetylcholine on the heart and blood pressure (B.P.) were not modified by strychnine or D-turbocurarine. Physostigmine sulphate potentiated the effects of injected acetylcholine without modifying the effects of strychnine and D-tubocurarine on vagal transmission. Dimethylphenylpiperazinium bromide also produced its characteristic effects on the heart and B.P. in the presence of strychnine and D-tubocurarine. The results indicate that strychnine and D-tubocurarine inhibition of vagal transmission is not a result of blockade of peripheral cholinergic receptors or cardiac vagal ganglia. This inhibition occurs presumably via a preganglionic presynaptic action.

Acetylcholine↗
PubMedDate not supplied

Whole body hyperthermia and preconditioning of the heart: basic concepts, complexity, and potential mechanisms.

Whole body hyperthermia (WBH) is a distinctive pathophysiological condition with significant impact on tissue metabolism and organ functions. WBH has been investigated as a promising adjunct therapy to the conventional chemo- or radiotherapy for treating certain types of cancer. Numerous studies have shown that WBH is associated with induction of heat shock proteins (HSPs), which in turn modulate cellular survival or death. A brief period of WBH (40-42 degrees C; 15-20 min) can induce delayed protection against lethal endotoxemia as well as various forms of injury in brain, heart, liver, lungs, small intestine, and skeletal muscle. This review article focuses on discussing the WBH-induced myocardial protection against ischemia/reperfusion injury. Most recently, possible involvement of protein kinase C, mitogen-activated protein kinases, nitric oxide, ATP-sensitive potassium channels, and neural peptides in the signal transduction pathways has been demonstrated. On the other hand, whether HSPs or antioxidant enzymes are the primary end-effector of the cardioprotection continues to be a matter of ongoing debates. It has also been recognized that the complex nature of WBH may be the responsible factor for the discordant results among various studies, especially across different animal species or strains, in terms of the time course and potency of WBH-induced cardioprotection. Nevertheless, a better understanding of the WBH-elicited myocardial ischemic resistance may have a wide spectrum of clinical implications as well as insightful inputs into the hyperthermic biology.

Animals↗
PubMedDate not supplied

Treatment seeking behaviour in sexually transmitted diseases.

The present study has been conducted to assess social and behavioural factors predisposing individuals suffering from sexually transmitted diseases to seek treatment and the role of the health provider in them. Out results showed that the demographic, socio-economic and behavioural characteristics of patients seeking treatment at alternative places and those attending the referral hospital in the first instance were comparable. Inhibition, time and distance were important considerations for selecting a health facility. Private clinics were the most preferred (72.4%) source of treatment. In 60.3% of cases written prescriptions were not given and advice regarding treatment of sexual partner was not there in any of the cases. 98.3% of the patients lacked awareness about their disease and 91.4% patients about the treatment they were receiving.

Adolescent↗
PubMedDate not supplied

Positron emission tomography imaging in evaluation of cancer patients.

Positron emission tomography (PET) is a diagnostic imaging technique that has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality. The most widely used radiotracer in PET is Fluorine18-fluorodeoxyglucose (F18-FDG), which is an analogue of glucose. The FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors PET has a high sensitivity and a high negative predictive value. PET with FDG is now the standard of care in initial staging, monitoring the response to the therapy, and management of lung cancer, colonic cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. Other indications of PET like bone tumor, ovarian cancer and cancer of unknown primary (CUP) has also been discussed in brief. The aim of this review article is to review the clinical applications of PET in various malignancies and only limited number of important studies will be discussed for this effort.

Fluorodeoxyglucose F18↗