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Biomedical subjects

R N Singh

Publications and source records attributed to R N Singh.

At least 19 recordsLinked to original sources
PubMed1992

A bacteriological study of the environment of pediatric ward and neonatal nursery.

The hospital environment is full of pathogens which may cause nosocomial infections. A bacteriological survey of hospital air, floor, water, milk and fomites was done. The air survey showed large number of bacteria carrying particles in air. A direct relation between floor area per person and bacterial contamination of air was established. The floor survey showed that there is abundance of bacteria on the hospital floors, much more than the accepted fair standards of house keeping. The hospital water had a high coliform and total bacterial count and stored tank water was more dirty. Neonatal nursery milk also had high total bacterial and coliform counts. Regular surveillance of hospital environment may help to reduce the incidence of cross infection.

Cross Infection↗
PubMed1991

Isolation and biochemical properties of four forms of glycosylated porcine prolactin.

Four isoforms of glycosylated prolactin (G-pPRL) were isolated from porcine pituitary glands by affinity chromatography and concanavalin A-Sepharose, based upon differences in their affinity for the lectin. Structural analysis indicated differences in the carbohydrate units of the four G-pPRLs. N-glycanase treatment cleaved the oligosaccharide from the G-pPRLs, establishing N-linked glycosylation. The binding of G-pPRLs to receptors from lactating rabbit mammary glands was only 3-8% that of nonglycosylated pPRL (NG-pPRL). The immunological crossreactivity of the G-pPRLs varied from 36 to 65% that of NG-pPRL. When tested in the pigeon crop sac bioassay, G-pPRLs were only 11-40% as active as NG-pPRL. The metabolic clearance rate of one of the G-pPRLs was slower and another faster than that of NG-pPRL. We conclude that there are several forms of G-PRL of variable immuno- and bio-potencies in the porcine pituitary, and that the current radioimmunoassay for the hormone does not measure the actual bioactivity.

Animals↗
PubMed1991

Fanconi's anemia.

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Child, Preschool↗
PubMed1990

Changes in the soft tissue chin after orthodontic treatment.

The study envisages changes in the contour of the soft tissue chin immediately and 5 years after orthodontic treatment in a group of 31 male and 29 female patients. The group was classified according to facial types and whether treatment involved extraction of first premolar teeth. The average age before treatment was 10 years 7 months, immediately after treatment it was 14 years 6 months, and 5 years after treatment was 21 years 6 months. The chin contour was studied from cephalometric x-ray tracings. The facial types--mesofacial, brachyfacial, and dolichofacial--were identified on the basis of cephalometric analysis. The chin thickness was registered at six different locations around the symphysis, from the point on the soft tissue chin corresponding to B point to the chin point corresponding to menton. Statistical means and standard deviations for all of the six chin thicknesses were calculated. It was found that the overall soft tissue chin thickness increased after orthodontic treatment. The females had less increase at all levels than the males. The dolichofacial group showed a greater increase in the soft tissue chin thickness after treatment. The mesofacial and brachyfacial groups of females showed no statistically significant increases. Regression tests of independent variables, including age, sex, facial type, and such other cephalometric measurements as 1 - A Pog, 1 to A Pog, mandibular plane, mandibular arc, facial axis, lower face height, and classification of malocclusion, indicated that age, sex, and facial type were the only variables that influenced the soft tissue chin thickness.

Cephalometry↗
PubMed1990

Glycosylated human prolactin: alterations in glycosylation pattern modify affinity for lactogen receptor and values in prolactin radioimmunoassay.

The receptor-binding properties of monomeric nonglycosylated human PRL (hPRL), glycosylated hPRL that does not bind to Concanavalin-A-Sepharose (G1-hPRL) and glycosylated hPRL that binds to Concanavalin-A-Sepharose (G2-hPRL) were tested in the lactating rabbit mammary gland RRA for lactogenic hormones. Variations in the glycosylation pattern of G-hPRL altered its receptor-binding properties, suggesting that the site of glycosylation may be proximal to the receptor-binding region. Relative potencies for the displacement of [125I]hPRL by hPRL, G1-hPRL, and G2-hPRL were 100%, 40%, and 26%, respectively. Relative potencies for displacement of [125I]G1-hPRL by hPRL, G1-hPRL, and G2-hPRL were 100%, 44%, and 69%, respectively; however, the displacement curve for G2-hPRL was not parallel to the others. When G2-hPRL was radiolabeled, there was no specific binding to lactogenic receptors. The presence of PRL receptor subtypes and/or kinetic cooperativity was suggested by the complexity of the binding isotherms. The immunoreactivities of the PRLs were tested in a homologous RIA, using polyclonal antiserum. The modification of the glycosylation pattern of hPRL significantly altered the RIA values for PRL. When hPRL was used as the radiotracer, the percent cross-reactivities of hPRL, G1-hPRL, and G2-hPRL were approximately 100%, 23%, and 17%, respectively. When G1-hPRL was used as the radiotracer, the percent cross-reactivities were approximately 100%, 135%, and 54% for hPRL, G1-hPRL, and G2-hPRL; however, the displacement curve for hPRL was not parallel to those of the glycosylated hPRLs. When G2-hPRL was used as the radiotracer, the percent cross-reactivities were approximately 100%, 32%, and 37% for hPRL, G1-hPRL, and G2-hPRL. These data point out that the glycosylation heterogeneity of hPRL is a factor that affects the diagnostic accuracy of hPRL determinations. Specific RIAs for each PRL are needed so that we can have valid and reliable measurements of each PRL isoform and consequently gain a better understanding of PRL's complex biological role.

Animals↗
PubMed1989

Two forms of glycosylated human prolactin have different pigeon crop sac-stimulating activities.

Two forms of glycosylated PRL (G-PRL) which differed in their binding properties to Concanavalin-A (Con-A) were isolated from human pituitary glands. One form, G1-hPRL, was only slightly retarded by Con-A; the other, G2-hPRL, was adsorbed by Con-A and could be eluted with methyl-D-manno-pyranoside, an indication of differing carbohydrate units in the two G-PRLs. Differences in type of glycosylation were also indicated by HPLC peptide mapping of tryptic digests of the two forms. The elution time for the tryptic peptide carrying the asparagine-linked carbohydrate unit varied for the two G-PRLs. The results point to the asparagine at position 31 as being the site of attachment of the carbohydrate. The carbohydrate structure influenced the crop sac-stimulating activity of the G-hPRLs. G1-hPRL had only about one fourth the activity of the reference standard (nonglycosylated ovine PRL, 35 IU/mg). The form that bound to Con-A, G2-hPRL, was equipotent to the reference standard. Because glycosylated forms have varying biological activities and are major components of circulating PRL, the physiological significance of serum concentrations of PRL measured by RIA will have to be reevaluated.

Amino Acid Sequence↗
PubMed1986

Flow disturbance due to venous valves: a cause of graft failure.

Late (greater than 1 year) postoperative angiographic studies in five patients revealed evidence of flow disturbance at the distal valve, when two valves were present in the body of a saphenous vein graft (SVG). This was associated with delayed clearance of radiopaque dye due to reduced velocity of flow. On follow-up, occlusion, thrombus formation, or development of atherosclerosis seemed to have occurred in anatomic relation to these valves. All five patients had one additional graft in a good state of preservation; three internal mammary artery (IMA) grafts, and 2 SVGs. The latter had only one venous valve, and the velocity of flow was good. It appears that good velocity of flow is essential to the integrity of coronary bypass grafts. The presence of more than one venous valve in a graft appears to cause flow disturbance and sluggish velocity, factors adversely affecting their integrity.

Aged↗
PubMed1986

Physiological adaptability: the secret of success of the internal mammary artery grafts.

Angiographic studies in 3 patients illustrate the physiological adaptability of internal mammary artery (IMA) grafts. Intact vascular smooth muscle permits the IMA grafts to retain a flexible caliber and a blood flow dictated by myocardial demands in the distribution of the grafted coronary artery. This physiological nature may be one of the reasons for their continued patency regardless of whether they are grafted to large or small coronary arteries. Further, this adaptable behavior permits use of the IMA even if its distal lumen is smaller than that of the recipient coronary artery, provided the anastomosis can be safely performed and the demand for flow is present.

Coronary Disease↗