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Biomedical subjects

H Singh

Publications and source records attributed to H Singh.

At least 487 records · Page 27Linked to original sources
PubMed1982

Pharmacokinetics of norethindrone acetate in women after the insertion of a single subdermal implant releasing norethindrone acetate.

The metabolic clearance rate (MCR) of norethindrone acetate (NETA) and norethindrone (NET) levels in plasma were studied after an iv injection of [3H]NETA in three women before and at 1 week, 1, 2 and 6 months following the insertion of a single silastic subdermal implant releasing microquantities of NETA. No significant change in the MCR of NETA was observed at 1 week (459 +/- 72 1/day), 1 month (489 +/- 113 1/day) and 2 months (522 +/- 144 1/day) compared with that of control (525 +/- 108 1/day). However, MCR of NETA showed significant increase in women exposed to continuous presence of NETA for a period of 6 months (608 +/- 121 1/day; P less than 0.025). NETA was rapidly and extensively metabolized into NET. At 1 week, 1, 2 and 6 months of study, NET was observed to be present in higher amounts compared with NETA. The production rate (PR) of progesterone decreased significantly at 2 and 6 months of NETA implant insertion compared with the PR before the insertion of implant.

Adult↗
PubMed1982

Significance of body weight as a performance parameter.

The laying performance of different body weight classes, defined on both a genetic and phenotypic scale, were compared. The distribution of pedigreed Leghorn breeders of both sexes were truncated on the basis of 30 week body weight into two classes: light (L) or heavy (H). The progeny then were classified according to parental mating types as either L X L, L X H, or H X H. Differences among these progeny groups defined the genetic scale. The phenotypic scale was derived separately by phenotypic truncation of the progeny distribution into light (L), medium (M), and heavy (H) body weight classes at 30 weeks. Differences in rate of lay and in egg mass output between classes were in poor agreement with respect to the two scales. Light birds were poorest egg producers on the phenotypic scale but were the best egg producers on the genetic scale. Superior egg production by the heavy-bird class during the late spring and early summer months of the year could not be demonstrated. Deviations in body weight sharply reflected poorer performance on the phenotypic scale but not the genetic scale. This emphasizes the dominant role of management, feeding, and disease control over the genetic influence in maintaining optimum size for satisfactory productivity.

Animals↗
PubMed1982

The Gaucher mouse.

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Acid Phosphatase↗
PubMed1982

Quantitative structure-activity studies. 2nd Communication: De novo calculations on antilipemic activity of 4-(4-chlorobenzyl)phenoxyacetic acid esters.

Quantitative structure-activity studies are carried out on antilipemic activity of 4-(4-chlorobenzyl)phenoxyacetic acid esters (1). Fujita-Ban group contributions are calculated for a variety of substituents. It is observed that when R1 is pyrid-3-ylmethyl, it has maximum contribution to activity and minimum toxic effects expressed in terms of liver growth. It is further noted that alkyl group substitution at position alpha to the carboxylic group leads to higher toxicities.

Animals↗
PubMed1981

Distribution of conduritol B epoxide in the animal model for Gaucher's disease (Gaucher mouse).

The time course of the distribution of the beta-glucosidase inhibitor [3H]conduritol B epoxide was determined in various organs of mice, which had received a single interperitoneal dose of the inhibitor. The epoxide is rapidly distributed over all tissues except brain where its concentration is only one-tenth of the average. This is considered an indication that the epoxide can pass the blood/brain barrier only with difficulty. A 4-fold enrichment is seen in the kidney. The inhibitor is excreted with a half-life of about 7 h; it is not metabolized. A parallel determination of beta-glucosidase activity in the tissues showed greater than 90% inhibition within 1 and 2 h and a beginning recovery between 4 and 12 h. The only exception was brain, where no effects could be seen after 1 h and where a subsequent decrease to 37% of normal was observed after 12 h.

Animals↗
PubMed1981

Biochemical polymorphic systems in inbred lines of chickens: a survey.

Biochemical polymorphic gene frequency profiles from blood samples of two outbred and seven inbred lines of chickens were studied for hemoglobin, albumin, transferrin, alkaline phosphatase, esterase II, and leucine aminopeptidase, and from egg samples of these lines for ovoalbumen, ovoglobulin (G2 and G3), and conalbumen. Complete gene fixation was found for hemoglobin, albumin, transferrin, ovalbumin, ovoglobulin, and conalbumin. The same alleles were fixed in each system in each line. For four systems, a particular allele within a system predominated in seven populations; gene frequencies ranged from 0.60 to 0.98. For esterases I and II, the genes Es-IB and Es-IIS ranged in frequency between 0.82 and 0.97, and between 0.64 and 0.93, respectively. For ovoglobulin, G2B ranged between 0.75 and 1.00 with four lines fixed for this allele. The rather remarkable similarity of gene frequency profiles among lines, several of which are only remotely related, suggests that certain characteristic polymorphic frequencies for these biochemical polymorphisms possess higher adaptive values in an evolutionary sense.

Animals↗
PubMed1981

Treatment of blood-induced glaucoma by trans pars plana vitrectomy.

Three patients are described who presented with blood-induced glaucoma. The cause of the vitreous hemorrhage was different for each patient, and included branch vein occlusion, diabetic retinopathy, and cataract extraction. The clinical findings common to all three cases consisted of degenerated red blood cells in the anterior chamber and vitreous cavity, a broken anterior vitreous face, open angles, and the absence of rubeosis iridis. Pars plana vitrectomy and anterior chamber irrigation resulted in normalization of intraocular pressure in each patient.

Aged↗
PubMed1981

The neuromuscular and autonomic blocking effects of azasteroids containing choline or acetylcholine fragments.

Nine analogues of the azasteroid muscle relaxant chandonium have been tested for neuromuscular blocking activity, ganglion blocking activity, inhibitory effects on cardiac muscarinic receptors, and for effects on noradrenergic transmission. Experiments were performed in anaesthetized cats and in isolated preparations. The two bisquaternary compounds HS-626 and HS-627, choline and acetylcholine-like analogues of chandonium respectively, were approximately equipotent with chandonium as neuromuscular blocking agents in the cat, but HS-672 possessed slightly more vagal blocking action. No evidence was obtained for ganglion block. The monoquaternary analogues, HS-408 and HS-465 and two 4-aza-androstanes, (HS-522 and HS-523) were more than 100 times less active than the bisquaternary compounds as neuromuscular blocking agents, and produced vagal blockade and ganglion blockade at sub-neuromuscular blocking doses. pA2 determinations in the chick biventer cervicis muscle, the guinea-pig atria and guinea-pig ileum showed that the bisquaternary compounds chandonium, HS-626 and HS-627 were much more potent in blocking cardiac than intestinal muscarinic receptors and that HS-626 possessed the widest margin between concentrations blocking the nicotinic receptors at the neuromuscular junction and the cardiac muscarinic receptors. Evidence for the three bisquaternary compounds blocking neuronal noradrenaline reuptake was obtained only at very high concentrations. HS-626 possessed a slightly more desirable spectrum of activities than chandonium, but the degree of improvement over the parent compound is insufficient to merit extensive clinical testing.

Acetylcholine↗
PubMed1981

The Arden grating acuity: effect of age and optical factors in the normal patient, with prediction of the false negative rate in screening for glaucoma.

The Arden contrast sensitivity was investigated in normal persons, cataract eyes, and glaucoma patients with only plates 6 and 7 of the Arden grating set. The mean score of 90 normal eyes on plate 6 was 9.50 +/- 2.29 and on plate 7 it was 9.44 +/- 2.32. The mean scores of patients with early cataract were 14.51 +/- 2.99 on plate 6 and 13.74 +/- 3.26 on plate 7. Several patients with cataract missed the grating on plate 7. Mydriasis and miosis did not affect contrast sensitivity in normal eyes. Mydriasis significantly improved contrast sensitivity in patients with early cataract. In patients with glaucoma enlargement of the pupil from a miotic state to near normal size significantly improved contrast sensitivity. It is predicted that if plate 6 and 7 are used in mass screening for glaucoma in the elderly, there will be a false negative rate of 83% for plate 6 and 52% for plate 7. A false positive rate of 17% is predicted.

Adolescent↗