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Biomedical subjects

H Singh

Publications and source records attributed to H Singh.

At least 469 records · Page 26Linked to original sources
PubMed1983

Quantitative structure-activity relationships. Antiinflammatory activity of salicylic acid derivatives.

A series of 28 substituted salicylic acids possessing antiinflammatory property is investigated for structure-activity relationships in light of the linear free energy related (LFER) and Fujita-Ban models. The Fujita-Ban group contributions have been calculated for 11 different substituents on the parent ring. It is observed that among these only phenyl group at position 5 increases the activity. The activity is found to increase further if electron withdrawing groups are attached to this phenyl substituent. The LFER analysis indicates that the electronic and partitioning effects of the substituents are important factors influencing the antiinflammatory activity. A statistically significant relationship with a correlation coefficient of the order of 0.9 explaining 71% of the variance is obtained using these substituent constants.

Animals↗
PubMed1983

Leiomyosarcoma of the mediastinum.

Leiomyosarcomas of the mediastinum are rare tumours, with only four cases reported in the literature. In the absence of any specific clinical pointer for diagnosis, proof comes through histopathologic study. One case of leiomyosarcoma of the superior mediastinum is reported here because of its rarity and an interesting histopathology.

Humans↗
PubMed1983

Muscle in chronic uremia--a histochemical and morphometric study of human quadriceps muscle biopsies.

This report describes qualitative and quantitative studies performed on ten muscle biopsies from chronic uremic patients on renal dialysis at light and electron microscopic (EM) levels. The muscle biopsies showed myopathic changes (variation in fiber size, central nuclei, and fiber splitting). Histochemical studies showed type II fiber atrophy and lipid deposits. The ultrastructural study showed disruption of myofibrillary architecture and subsarcolemmal deposits of glycogen, mitochondria, and lipids. Quantitative estimations of the subcellular organelles revealed a statistically significant increase in lipid and glycogen contents of the muscle. The myopathic changes, type II atrophy, and lipid and glycogen deposits in chronic uremic patients raise the question of the effects of uremia and/or chronic dialysis on muscle metabolism.

Adult↗
PubMed1982

Pregnancy after surgical correction of tetralogy of Fallot.

Forty pregnancies have been documented in 27 patients with surgically corrected tetralogy of Fallot. Infertility was uncommon and there were no premature births and few abortions or small-for-dates babies; this suggests that surgery that corrects cyanosis improves the outcome of pregnancy by correcting the fetal environment. Pregnancy was well tolerated and there were no serious cardiac complications. Thirty of the 31 infants examined were normal, the one abnormal infant having pulmonary atresia. A patient with no major residual defects after surgery for tetralogy of Fallot may be reassured that pregnancy will be well tolerated and that delivery may be managed in the normal manner.

Female↗
PubMed1982

Mithramycin- and triethylene melamine- induced sperm abnormalities in Lakeview hamsters.

The sperm abnormality-inducing action of two potential mutagenic agents mithramycin and triethylene melamine (TEM), in inbred Lakeview hamsters was studied and results compared with similar investigations in mouse. Test hamsters received subacute intraperitoneal exposures ranging from 0.01 to 0.25 mg/kg body weight with either agent for 5 consecutive days. Testis weights, epididymal sperm numbers, and body weights were also monitored at weeks 1, 4, and 10 after treatment. Mithramycin-treated hamsters showed 21 times more sperm abnormalities than control (25% vs. 1.2%) whereas TEM elevated sperm abnormalities by eight fold. The frequency and type of aberrant sperm varied with dose and time, being the highest at weeks 1 or 4, rather than week 10, with either agent. Sperm number and testis weights remained depressed considerably from 4 to 10 weeks after treatment with either agent. Body weights in chemically treated hamsters remained within 28% of control for the test period. Even though our findings were in general agreement with those reported for mouse, the magnitude of the response and the stage of spermatogenic sensitivity in the chemical induction of sperm abnormalities in the two species were different.

Animals↗
PubMed1982

Novel mode of contraception using polymeric hydrogels. I.

A new method of fertility control has been proposed and tested. The technique involves the use of the polymer, which when injected into the vas deferens lowers the pH sufficiently so as to kill the spermatozoa passing through. The polymer provides an acidic environment for a prolonged time and slowly erodes. The fertility may be restored after complete solubility of the polymer itself over a period of time or by flushing it with a suitable solvent. This method of male contraception is nonsurgical, nonocclusive, and reversible.

Contraception↗
PubMed1982

Morphogenesis of the mitochondrial alterations in muscle diseases.

In this paper we present sequential morphologic changes produced in rat muscle mitochondria. Respiratory toxins such as crotoxin (rattle-snake venom) and 2,4-dinitrophenol (DNP-an uncoupler of oxidative phosphorylation) were injected in rat quadriceps muscle and the mitochondrial alterations were studied at various time intervals. The series of mitochondrial changes consisted of rounding and swelling of mitochondria, unfolding of the cristae as straight lines, formation of the concentric rings, appearance of paracrystalline inclusions, formation of multiple vesicles and finally vacuole formation. These changes were comparable to the range of mitochondrial alterations seen in the human material examined. Similarity of the time-related mitochondrial changes in the rat to the spectrum of changes observed in human muscle biopsies suggests that the mitochondrial alteration in the human muscle disorders is a stepwise process in which respiratory alterations and calcium ion may play a role.

2,4-Dinitrophenol↗
PubMed1982

Growth responses of race 222 of Puccinia graminis tritici in defined media.

Aseptically produced uredospores of race 222 of Puccinia graminis tritici were seeded on defined liquid media containing Czapek's minerals, sucrose or glucose, and various combinations and concentrations of 19 amino acids and a tripeptide, glutathione. The cultures were incubated in the dark at 16--17 degrees C. A medium containing a high concentration of aspartic acid (5988 ppm), cysteine (557 ppm), and glutathione (1014 ppm) supported a profuse growth of the fungus in the form of floating white, fluffy, and vegetative colonies. A sulphur-containing amino acid appears to be essential for the axenic culture of the fungus.

Amino Acids↗