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Biomedical subjects

M K Agarwal

Publications and source records attributed to M K Agarwal.

At least 19 recordsLinked to original sources
PubMed1992

Receptor mediated mineralocorticoid action in alga cell mutants.

The multiplication of Chlamydomonas cells can be arrested by the spirolactone derivative RU 26752 and this is fully reversible by the natural hormone aldosterone. Continuous growth in the presence of RU 26752 led to the isolation of a population subsequently resistant to the action of mineralocortoid analogues, due possibly to the selection of mutant cells. Immunophotochemical evidence is provided for a 52 kDa protein that possesses functional steroid and DNA binding domains. Alga cells therefore appear to respond to steroid hormones in a manner similar to the mammalian systems, possibly via a receptor that may represent a pygmy ancestor of the latter day steroid receptor superfamily.

Animals↗
PubMed1992

Mineralocorticoid hormone action in plant cells.

The multiplication of Chlamydomonas reinhardtii wild type cells can be arrested by the spirolactone RU 26752 and this is fully reversible by the natural mineralocorticoid aldosterone. Evidence is presented for a 52 kDa protein that possesses functional DNA and ligand binding domains and tests positive for mineralocorticoid receptor-like activity by immuneprecipitation, macroaggregation, and photoaffinity. The regulation of trans-activation by steroid hormones in the animal world would therefore appear to be just as valid for the plant kingdom, thereby providing a new model for genetic analysis.

Aldosterone↗
PubMed1992

Generation of polyclonal antibodies against the mineralocorticoid receptor and analysis of mineralocortin in rat myocardium by immunophotochemistry.

Fawn, Burgundy rabbits were immunized with the mineralocorticoid receptor (MCR) purified biochemically from rat kidney by a simple, two step procedure. High anti-MCR titers were observed in radioimmunoassays just 3 weeks after the initial injection and increased further with time. Western blot analysis revealed a single band of 94-98 kDa in renal and cardiac cytosol from the rat, like the antigen prepared biochemically. The two atria from beef heart exhibited far greater MCR-positivity compared to the two ventricles, suggesting physiological relevance. The receptor was also photolabelled for the first time with promegestone in this very 94-98 kDa region which could be displaced by the antagonist RU 26752 specific to MCR. The immune IgG precipitated 3H-aldosterone or 3H-RU 26752-MCR complexes from rat heart, and displaced the MCR-antagonist complex to high molecular weight regions during gel permeation chromatography on Sephacryl columns. Immunofluorescent labelling showed that MCR was widely distributed in the cytoplasm in rat myocardium with limited staining in what appeared to be the nuclear compartment. These open up the possibility of large scale purification of the endogenous mineralocorticoid binding protein, mineralocortin, for detailed physicochemical characterization. The technique of photoaffinity labelling presented here should also help delineate the nature of the steroid binding domain in the MCR.

Animals↗
PubMed1992

Rat lung possesses the mineralocorticoid receptor.

Lung cytosol from male, adrenalectomized rats was screened for the mineralocorticoid receptor (MCR) by a polyclonal antiserum raised in the rabbit against rat renal antigen. Western blot analysis revealed a single 98 kDa band, like the MCR purified biochemically. The MCR could also be photolabelled for the first time by 3H-R 5020 in this very 98 kDa region that was displaced by RU 26752 specific to MCR. Immune IgG was able to precipitate the MCR-3H-RU 26752 complex, and to displace the same to high molecular weight regions during gel permeation chromatography on Sephacryl columns. Thus, MCR mediated actions need to be redefined. Furthermore, the technique of photochemical labelling forms a novel tool to assess MCR specificity, and to dissect its structure and function.

Animals↗
PubMed1992

Immunophotochemical analysis of mineralocortin by polyclonal antibodies against the native receptor from rat kidney.

We have obtained a polyclonal antiserum by immunizing fawn Burgundy rabbits with the mineralocorticoid receptor (MCR) purified biochemically from rat kidneys. High titers of anti-MCR activity were obtained in radioimmunoassays within 3 weeks and increased with a booster shot. In Western blot analysis, the antibody revealed a major band of 94-98 kDa in renal cytosol from rat and beef kidneys. We also developed a fluorographic procedure where the MCR linked covalently to tritiated R-5020, following ultraviolet irradiation, gave imprints superimposable on the Western blot profile. The fluorographic pattern was specific since it was largely abolished in the presence of cold RU 26752 that is specific to MCR, or mineralocortin. The immune IgG precipitated rat renal MCR(-)[3H]RU 26752 complexes in a dose-dependent manner and also recognized MCR bound to the natural hormone aldosterone. During gel permeation chromatography on Sephacryl, the elution profile of [3H]RU 26752 shifted to high-molecular-weight regions in the presence of immune IgG. The receptor protein could be immunolocalized primarily to the principal cells of the collecting duct in rat kidney but the intercalated cells and glomeruli were not labeled, contrary to beef kidney where a uniform pattern of immunostaining was evident. These should permit large-scale purification of the MCR for detailed physicochemical studies and for screening of the MCR-positive tissues during various pathophysiological syndromes.

Adrenalectomy↗
PubMed1992

Modification of septic shock in mice by the antiglucocorticoid RU 38486.

The survival rate in murine septic peritonitis was inversely proportional to the size of the needle used for cecal puncture following ligation below the ileocecal valve. The smaller, 20-gauge needle permitted 20% survival. Only 20% of the animals survived 24 hr after cecal puncture with a 20-gauge needle compared to 90% survival after 5 days if mice had been rendered tolerant to lipopolysaccharide (LPS) prior to the induction of peritonitis. A single intravenous injection of 1 mg RU 38486, concurrent with puncture with a 21-gauge needle, lowered survival to only 15% from the control level of 71%. This same dose of the antiglucocorticoid decreased the survival rate to only 35% from 90% in the tolerant group. Tolerance to the lethal effects of endotoxins, possibly responsible for resistance to septic peritonitis, was also abolished by the antiglucocorticoid. Just 1 mg RU 38486 lowered the survival rate to 5% if it was given with 600 micrograms LPS, which permitted 95% survival in LPS-tolerant mice and 60% survival in normal controls. Whereas both 1 mg RU 38486 and 100 micrograms dexamethasone, given alone, sensitized mice to septic peritonitis (15% and 30% survival, respectively), their combined effects neutralized each other, leading to 80% survival vs. 71% in the control group. Thus receptor-mediated glucocorticoid-dependent mechanisms appear important in the pathogenesis of both endotoxin and septic shock, albeit to varying degrees and in a seemingly contradictory manner.

Animals↗
PubMed1979

Search for antiglucocorticoid activity in rat liver in vivo.

Estradiol and testosterone both lowered endogenous liver glycogen and at 20-fold higher doses impaired triamcinolone acetonide mediated glyconeogenesis in adult adrenalectomized male rats. Neither steroid influenced liver tyrosine transaminase although tryptophan pyrrolase activity was depressed by testosterone. Progesterone increased liver tryptophan pyrrolase but did not influence other parameters. Cortexolone did not alter either of these processes whereas cortisol induced both enzymes and, at much higher dose levels, gluconeogenesis. Binding of 3H-triamcinolone acetonide to its cytoplasmic receptor in vitro was left unaffected in presence of 20-fold greater concentration of either sex steroid but almost totally abolished by cold, homologous molecules. Similar results were obtained by 3H-cortisol except that estradiol partially competed for 3H-cortisol binding sites even at 20-fold greater concentrations of cold estradiol. Separation on DEAE-cellulose-52 and Ultrogel 44 columns revealed binding of all steroids to macromolecules of comparable physicochemical properties although the ratios of binding to the various subpopulations of the receptor were a function of the steroid in question. These results are discussed in terms of sex steroid binding to different moieties of a complex, heterogeneous, polymorphic protein rather than inhibition of binding to the active configuration acquired in presence of an inducer.

Animals↗
PubMed1979

Neurofibroma of the maxillary antrum.

A rare case of neurofibroma of the maxillary antrum is reported. The tumor was removed via a Caldwell-Luc approach. Its histopathologic characteristics are described.

Humans↗
PubMed1979

Bronchiectasis: a cause of pulmonary symptoms in heroin addicts.

Extensive and severe bronchiectasis was found in 7 heroin-addicted individuals with pulmonary symptoms whose chest roentgenograms were not suggestive of severe airway disease. Abnormalities consisted of varicose and cylindrical alterations. Pulmonary function tests revealed airflow obstruction, decreased lung volumes, and diffusion capacity impairment. Arterial blood gas analysis demonstrated mild hypoxemia in all patients and chronic hypocapnia in 4. Serial pulmonary function tests in 2 patients revealed only modest improvement in the degree of airflow obstruction. The occurence of bronchiectasis appeared to be related to episodes of heroin-induced pulmonary edema and infection.

Adult↗
PubMed1979

Studies on allergenic algae of Delhi area: botanical aspects.

To study distribution of algae in and around Delhi aerobiological surveys were undertaken for two consecutive years (September, 1972, to August, 1974). The surveys were accomplished by (a) slide exposure method and (b) culture plate exposure method. A total of 850 slides were exposed using Durham's gravity sampling device. Of these, 560 slides were exposed during 1973 (272 slides at two meter and 288 at ten meter height) and the rest (290 slides) were exposed during 1974 at ten meter height. A total of 858 culture plates were exposed (276 for one hour and 282 for two hours) during 1973 and the rest (300 culture plates) were exposed during 1974 at ten meter height for two hours duration only. Air was found to be rich in algae flora during the months of September to November. The dominant forms of algae present were all blue greens. This might be due to the relative greater resistance of blue green algae to unfavorable conditions.

Air Microbiology↗
PubMed1979

Arrhythmogenic effects of orally administered bronchodilators.

The respiratory and circulatory effects of orally administered ephedrine sulfate, 25 mg, aminophylline, 400 mg, terbutaline sulfate, 5 mg, and placebo were evaluated in 20 patients with ventricular arrhythmia by a double-blind crossover method. The bronchodilator effect of terbutaline was similar to that of aminophylline over four hours but superior to ephedrine at the fourth hour. Both terbutaline and ephedrine exhibited chronotropic effects, with the effect of terbutaline greater than that of ephedrine at the fourth hour. The effect of aminophylline on heart rate did not differ from placebo. Only terbutaline was associated with an increase in ventricular ectopic beats. Ventricular tachycardia occurred in three patients treated with terbutaline and in one patient with ephedrine. There were no significant changes in blood pressure. Orally administered terbutaline should not be regarded as safer than orally administered ephedrine or aminophylline in patients with arrhythmias.

Adult↗
PubMed1979

Respiratory allergy to algae: clinical aspects.

A comprehensive investigation was done to evaluate the allergenic algae in the Delhi area. Results of 4,000 skin tests performed on 400 patients suffering from naso-bronchial allergy and 300 skin tests on 30 healthy persons with 10 common algae isolated from the Dehli atmosphere are presented and compared. Positive skin reactions (1+ to 3+) to algae extracts ranged from 25.7% with Lyngbya major extract to 1.7% with Oscillatoria simplicissima extract; in healthy non-allergic volunteers there were no positive skin reactions. The Prausnitz-Küstner (PK), bronchial provocation and conjunctival tests were negative in patients with negative skin reactions; in patients with positive skin reactions PK was positive in 70.9%, bronchial provocation in 50% and conjunctival in 48.5%. Levels of total IgE in patients with naso-bronchial allergy were higher, ranging from 1,225 international units per ml to 1,550 international units per ml, while in healthy volunteers the values were less than 885 international units per ml.

Allergens↗