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Biomedical subjects

R Singh

Publications and source records attributed to R Singh.

At least 595 records · Page 33Linked to original sources
PubMed1987

Photosynthetic Carbon Fixation Characteristics of Fruiting Structures of Brassica campestris L.

Activities of key enzymes of the Calvin cycle and C(4) metabolism, rates of CO(2) fixation, and the initial products of photosynthetic (14)CO(2) fixation were determined in the podwall, seed coat (fruiting structures), and the subtending leaf (leaf below a receme) of Brassica campestris L. cv ;Toria.' Compared to activities of ribulose-1,5-bisphosphate carboxylase and other Calvin cycle enzymes, e.g. NADP-glyceraldehyde-3-phosphate-dehydrogenase and ribulose-5-phosphate kinase, the activities of phosphoenol pyruvate carboxylase and other enzymes of C(4) metabolism, viz. NADP-malate dehydrogenase, NADP-malic enzyme, glutamate pyruvate transaminase, and glutamate oxaloacetate transaminase, were generally much higher in seed than in podwall and leaf. Podwall and leaf were comparable to each other. Pulse-chase experiments showed that in seed the major product of (14)CO(2) assimilation was malate (in short time), whereas in podwall and leaf, the label initially appeared in 3-PGA. With time, the label moved to sucrose. In contrast to legumes, Brassica pods were able to fix net CO(2) during light. However, respiratory losses were very high during the dark period.

Journal Article↗
PubMed1987

Effect of contraceptives on the adhesion of Escherichia coli to uroepithelial cells.

We studied the effect of female ovarian hormones present in contraceptive preparations on six strains of Escherichia coli isolated from patients with urinary tract infections. These strains had variable attachment potential. To study this effect in vivo, we gave a woman an oral contraceptive preparation and then compared the amount of attachment to her uroepithelial cells before and after hormone administration. To study the in vitro effect, we exposed uroepithelial cells from this same woman to different hormone concentrations for up to 18 hr and noticed any alteration in adhesion. We observed that in vivo as well as in vitro exposure of uroepithelial cells to hormones enhanced the adhesion of all E. coli strains.

Adult↗
PubMed1987

Changes in hexokinase isoenzymes in regions of rat brain during thyroid deficiency.

In this work, activities of hexokinase isoenzymes Type I and Type II were measured in the soluble and particulate fractions from the brain regions (cerebral hemispheres (cerebrum), cerebellum and brain stem) of the thyroidectomized adult rats as well as of the thyroidectomized rats administered with triiodothyronine. Thyroidectomy generally decreased the hexokinase activity associated with particulate and soluble fractions. Hexokinase Type II isoenzyme was more affected than the Type I isoenzyme. Administration of triiodothyronine to the hypothyroid rats abolished the effect of thyroidectomy. Adult brain enzymes have been generally considered not be affected by thyroid hormones. The data obtained in this work are suggestive of an effect of thyroid hormones on hexokinase in the adult brain. Since the effects of thyroidectomy on the energy metabolism of the heart tissue are well known, the heart tissue was also studied for comparison.

Animals↗
PubMed1986

Effect of intraventricular infusion of an angiotensin II antagonist on 125I-angiotensin II binding in rats.

The effects of chronic (six day) intracerebroventricular (i.c.v.) infusion of an angiotensin II antagonist, sarcosine1, isoleucine8 angiotensin II ([Sar1, Ile8]Ang II), (500 ng/microliter per hour) was studied. Specific 125I-Ang II binding site density and binding affinity in the hypothalamus-thalamus-septum-midbrain (H-T-S-M) region of the brain and the adrenal medulla did not differ significantly between [Sar1, Ile8]Ang II treated and control (0.9% saline) rats. However, 125I-Ang II binding to the adrenal cortex was significantly reduced by i.c.v. infusion of [Sar1, Ile8]Ang II. The drinking response to microinjection of Ang II was blunted for up to seven days of [Sar1, Ile8]Ang II infusion. Thus, although [Sar1, Ile8]Ang II effectively blocked the central Ang II receptors, chronic infusion of this Ang II antagonist did not appear to cause alterations in brain H-T-S-M Ang II receptors, suggesting that brain Ang II receptors in normal rats do not undergo homologous regulation.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1986

A new "marker" protein for astrocytes.

A monoclonal antibody (Mab J1-31) has been produced by using human brain homogenate as immunogen in mouse. Double-label immunofluorescence microscopy on cryostat sections of human, rabbit and rat brain, reveals staining of cells that are also stained with antiserum to glial fibrillary acidic protein (GFAP, a commonly used marker protein for astrocytes). However, there is no decrease in staining due to Mab J1-31 in sections incubated in antiserum to GFAP prior to incubation with the J1-31 ascites fluid. Immunoprecipitation of aqueous and detergent extracts of brain homogenate gives a single band at 30K by SDS-PAGE followed by autoradiography. Immunoelectron microscopy shows that the J1-31 antigen is associated with the cytoskeleton. Thus, the Mab J1-31 recognizes a new protein present in GFAP positive cells (astrocytes) in the brain.

Animals↗
PubMed1986

Influence of transsphenoidal hypophysectomy on visual deficit due to a pituitary tumour.

The effect of transsphenoidal hypophysectomy is presented in 60 patients with visual impairment due to a pituitary adenoma, derived from a total series of 194 patients. The preoperative visual acuity and visual fields were compared with those one year after operation. The visual field loss was estimated using a semi-quantitative method. Seventy-two eyes had diminished visual acuity, and this improved in 45 eyes (63%). Visual field loss was present in 102 eyes and this improved in 71 eyes (70%). Improvement of either visual acuity and/or visual field was found in 84 eyes (78%). In 16 patients (27%) vision became normal after operation. Improvement of the visual acuity was usually accompanied by an improvement in the visual fields.

Adenoma↗
PubMed1986

Changes in the concentrations of parathyroid hormone and ionic calcium in the plasma of laying hens during the egg cycle in relation to dietary deficiencies of calcium and vitamin D.

The concentrations of biologically active parathyroid hormone (PTH) and ionic calcium (Ca2+) were determined in the plasma of control and calcium-deficient laying hens during the egg cycle. The same measurements were made in hens that had ceased laying because of a deficiency of vitamin D and in normal hens during pauses in egg production. Changes in the concentration of Ca2+ during the egg cycle followed the same pattern and were of the same magnitude in the control and calcium-deficient birds: mean levels were high when egg shell calcification was not occurring and they were at least 0.10 mmol/litre lower during active shell formation. There was a reciprocal relationship between the concentrations of PTH and Ca2+; thus, PTH values were high during shell calcification and low before shell formation began and after oviposition. Mean concentrations of PTH in the birds given the low-calcium diet were more than twice as high as in the control birds both during shell formation at 0700 hr (12.85 and 5.95 pg/ml, respectively) and after oviposition at 1600 hr (4.25 and 0.55 pg/ml, respectively). The results of these experiments provide direct evidence that the mobilization of skeletal calcium for egg shell formation is under parathyroid control. In the non-shell-forming control and vitamin D-deficient birds there were no significant changes over the 27-hr sampling period in either PTH or ionic calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗