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Biomedical subjects

R S Misra

Publications and source records attributed to R S Misra.

At least 91 records · Page 5Linked to original sources
PubMed1981

Effect of aflatoxin B1 on chromatin-bound ribonucleic acid polymerase and nucleic acid and protein synthesis in germinating maize seeds.

The treatment of germinating maize seeds (cv. Ganga 2) with aflatoxin B1 resulted in suppression of ribonucleic acid (RNA), protein, and deoxyribonucleic acid (DNA) synthesis at 3, 4, and 5 h, respectively. At or below the concentrations inhibitory for these in vivo syntheses, the toxin inhibited chromatin-bound DNA-dependent RNA polymerase activity. The synthesis of both polyadenylated and non-polyadenylated RNA was inhibited, but the effect on the former was more pronounced. Equilibrium dialysis and difference spectral and viscometric analyses showed a binding of aflatoxin B1 to DNA isolated from the seeds. It is proposed that the inhibition of RNA synthesis in maize seeds by the toxin is due to the interference with the RNA polymerase activity, which seems, at least partially, due to the impairment of DNA template functions.

Aflatoxin B1↗
PubMed1980

Correlation between monoamine oxidase inhibitors and anticonvulsants.

Monoamine oxidase inhibitory and anticonvulsant properties of 2-substituted styryl-6-bromo-3-(4-ethylbenzoate/4 benzhydrazide)-4-quinazoles are studied. All styryl quinazolone esters except compound number 9 exhibited monoamine oxidase inhibitory properties during oxidative deamination of kynuramine. Corresponding hydrazides were found to have relatively higher activity. All these quinazolones were able to protect against pentylenetetrazol induced seizures. These observations in general do not prove that monoamine oxidase inhibitory properties represent the biochemical basis for the anticonvulsant activity of these compounds.

Animals↗
PubMed1978

IV. Synthesis and assay of analogs of adenosine 3',5'-diphosphate as inhibitors of bovine adrenal estrogen sulfotranferase.

Analogs of adenosine 3',5'-diphosphate are described which aid in the characterization of the inhibition of estrone sulfurylation by 3'-phosphoadenosine 5'-phosphosulfate as mediated by bovine adrenal estrogen sulfotransferase (3'-5'-phosphosulfate:estrone 3-sulphotransferase, EC 2.8.2.4). The facile conversion of ribonucleosides to 2',3'-cyclic phosphate 5'-phosphate in neat pyrophosphoryl chloride is utilized to provide a reliable route to the requisite intermediates for enzymatic regiospecific conversion to ribonucleoside 3',5'- and 2',5'-diphosphates. The importance of the 3'-phosphate ester to inhibition of estrone sulfurylation is confirmed by Ki measurements. Replacement of the 6-amino group by hydrogen or oxygen leads to considerable loss in affinity for the enzyme as does also dimethylation of the exocylic amino group. Alterations in the pyrimidine ring are not well tolerated by the sulfotransferase but modifications in the imidazole ring as in tubercidin (7 -deazaadenosine) and 8-bromoadenosine 3',5'-diphosphate lead to an enhanced affinity. The latter findings are discussed in terms of an hypothesis of stacking of the aromatic ring of the estrogen substrate and the purine moiety and its analogs.

Adenine Nucleotides↗
PubMed1977

Studies on bovine adrenal estrogen sulfotransferase. III. Facile synthesis of 3'-phospho- and 2'-phosphoadenosine 5'-phosphosulfate.

A practical synthesis of 3'-phosphoadenosine 5'-phosphosulfate (IV) in yields of 68-72% from adenosine 2',3'-cyclic phosphate 5'-phosphate (II) is described. Reaction of II with triethylamine-N-sulfonic acid affords adenosine 2',3'-cyclic phosphate 5'-phosphosulfate (III) which, on treatment with ribonuclease-T2, provides IV. Spleen phosphodiesterase, on the other hand, converts III to 2'-phosphoadenosine 5'-phosphosulfate (V). The biological activity of IV, measured by sulfate transfer to [6,7-3H2]estrone as mediated by bovine adrenal estrone sulfotransferase (3'-phosphoadenylyl-sulfate:estrone 3-sulfotransferase, EC 2.8.2.4), is identical with that obtained with a sample of IV prepared by an established biochemical procedure. By contrast, V exhibits approximately one-third the activity of the natural isomer.

Adenine Nucleotides↗
PubMed1976

Synthesis of substituted thiobenzoxazoles/benzothiazoles: inhibition of cellular respiratory and monoamine oxidase activities and anticonvulsant property.

Several 2-(substituted alkoxy/hydrazinocarbonyl acetanilidothio)benzoxazoles/benzothiazoles were synthesized and characterized by their sharp melting points, elemental analyses, and IR spectra. All thiobenzoxazoles/benzothiazoles possessed low anticonvulsant activity, which was reflected by the 10-40% protection afforded by these compounds against pentylenetetrazol-induced convulsions. All thiobenzoxazoles/benzothiazoles inhibited selectively the nicotinamide adenine dinucleotide (NAD)-dependent oxidation of pyruvate, DL-isocitrate, and alpha-ketoglutarate by rat brain homogenates. NAD-independent oxidation of succinate remained unaltered. All 2-(substituted hydrazinocarbonyl acetanilidothio)benzoxazoles/benzothiazoles inhibited monoamine oxidase activity of rat brain homogenates. Greater monoamine oxidase inhibition was observed with thiobenzothiazoles than with the corresponding thiobenzoxazoles/benzothiazoles was found to be unrelated with their ability to inhibit cellular respiratory and monoamine oxidase activities of rat brain homogenates.

Animals↗
PubMed1975

Synthesis of 2-(4-arylthiosemicarbazidocarbonylthio)benzthiazoles and their monoamine oxidase inhibitory and anticonvulsant properties.

Ten 2-(4-arylthiosemicarbazidocarbonylthio)benzthiazoles were synthesized, characterized, and evaluated for their monoamine oxidase inhibitory and anticonvulsant activities. All substituted benzthiazoles inhibited activity of monoamine oxidase in rat brain homogenate where the degree of enzyme inhibition was higher with kynuramine as compared to tyramine and 5-hydroxytryptamine as the substrates. All substituted benzthiazoles possessed measurable anticonvulsant activity against pentylenetetrazol-induced convulsions.

Animals↗
PubMedDate not supplied

A study of cutaneous tuberculosis in children.

Sixty-three children out of a total of 199 patients seen with cutaneous tuberculosis during a 7-year period were included in this study. Culture was positive in only four, and the diagnosis was based on clinical examination, tuberculin reaction, histopathology, and response to antitubercular therapy. Forty had lupus vulgaris (LV) and 23 scrofuloderma (SD). The lower half of the body was predominantly affected in those with LV, and keratotic and hypertrophic forms were frequently encountered. LV planus mainly affected the face. Ulcerative and atrophic types of LV were infrequent. Extensive lesions in three children led to disfiguring scars and contractures. Scrofuloderma often involved the cervical group of lymph nodes followed by the inguinal, submandibular, and axillary groups. As compared to skin tuberculosis in adults, regional lymph node involvement in LV was more common, and a combination of both LV and SD was less frequent in children. No difference in clinical presentation could be detected between the BCG vaccinated and unvaccinated children. Tuberculous infection either in the lungs or the bones was present in eight children. An HIV test done in five patients with widespread lesions was negative. Irregular therapy or late diagnosis leading to serious complications, inadequate parental or community support, and lack of awareness among practitioners are the problems to be remedied.

Adolescent↗
PubMedDate not supplied

Increasing trend of HIV seropositivity in a sexually transmitted diseases centre and epidemiology of HIV seropositive individuals.

11,539 STD clinic attenders and 20,897 antenatal clinic (ANC) attenders at a New Delhi hospital were screened for HIV antibodies by ELISA over a 3-year period. Results were confirmed by Western Blot. A low HIV seropositivity rate (1 per 1000) with an increasing trend in 1993 (4 per 1000) was observed in the STD attenders as against 0.1 per 1000 in the normal control populations. Most of the STD attenders including all the HIV seropositives had heterosexual contact with female sex workers. Both the HIV seropositive ANC attenders acquired the infection through blood transfusion. Thirteen of 23 HIV positive STD attenders had genital lesions, 5 having ulcerative and 8 having nonulcerative STD. Their clinical presentation did not differ from the HIV negative cases but the therapeutic response in 4 was altered. None had signs of symptoms of ARC/AIDS. Two out of 6 spouses and a 2-year-old child of HIV seropositive patients were seropositive. Increasing HIV seropositivity observed in this study reflects the changing situation in the country and highlights the importance of improvement of surveillance, early diagnosis and combined approaches to the management and control of STDs and HIV.

Adult↗