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Biomedical subjects

B P Singh

Publications and source records attributed to B P Singh.

At least 19 recordsLinked to original sources
PubMed1992

Photostimulation of blackheaded bunting: subjective interpretation of day and night depends upon both photophase contrast and light intensity.

Blackheaded buntings were exposed to constant dim light (approximately 2 lux) for 77 days and subsequently to 12:12 illumination, consisting of either dim light:complete darkness (dl:dk) (2:0 lux) or bright light:dim light (bl:dl) (10, 35, and 90 lux:2, 10, and 35 lux, respectively, with 180 degrees bl:dl transitions) for 2-3 weeks each. Birds were unstimulated until day 100, under dim LL (dl:dl) and 12dl:12dk. Photostimulation with a significant increase (p less than 0.001) in average body weight and testis volume occurred on exposure to 12bl:12dl (10:2 lux); birds remained fat and testes were enlarged until the end (day 173) of the experiment. Locomotor activity also did not have a discernible pattern under the nongonadostimulatory photoregimes. Birds became active in the bright photophase (subjective day) of 12bl:12dl (10:2 lux) on day 5 (day 105 of the experiment), but beginning on day 113 more intense perch-hopping was initiated in the dim photophase (subjective night), indicating the appearance of nocturnal migratory restlessness in the caged birds. A 180 degrees transition in the bl:dl photophases at this time for 2 weeks resulted in complete shift in the timing of daytime and nighttime activity. This trend is maintained under all subsequent 12bl:12dl exposures. These results suggest that the light intensity required for photostimulation in the blackheaded bunting is absolute, and that the subjective interpretation of day and night depends upon the photophase contrast, as well.

Animals↗
PubMed1992

Evaluation of protein assay methods for pollen and fungal spore extracts.

The usual procedures available for protein estimation of biological extracts often give variable results due to presence of many peptides and coloured materials. To identify a suitable method for allergenic extracts, protein was estimated from common pollen and fungal antigens by modified Lowry's (ML), Bradford (B), micro-Kjeldahl (MK), Bicinchoninic acid (BCA) and modified BCA (MBCA) assays. Bradford assay resulted in low protein values, whereas BCA method gave very high values in general. Statistical analysis of the results revealed similarity between protein values quantitated by MK, ML and MBCA methods for most of the extracts. Graded volumes of the extracts on subjecting to protein estimation by these three methods showed linear response, while recovery of a protein (bovine serum albumin) added to the extracts was greater than 90%.

Allergens↗
PubMed1992

A study on antigenic and allergenic changes during storage in three different biological extracts.

The stability of three allergens common in tropical countries was evaluated under different storage conditions. Prosopis juliflora (PJ), Rhizopus nigricans (RN), and wheat dust (WD), were taken as representatives of various groups of allergens viz, pollen, fungi and dust. The extracts were stored in buffer containing phenol (0.4%) or glycerol (50%) at temperatures ranging from 4-55 degrees C for 15 to 60 days. Protein content of PJ extract was reduced remarkably when it was stored at 40 degrees C for 45 days. Thin layer isoelectric focusing and rocket immunoelectrophoresis of PJ showed that certain antigenic proteins degrade rapidly even at 25 degrees C as early as day 15. However, two to three proteins of PJ remain stable at a higher temperature (40 degrees C) for two months. Relative radioallergosorbent test (RAST) inhibition showed substantial loss of allergenic activity in all the three extracts, when stored at higher temperatures (25-55 degrees C) even for short durations, i.e., 15 days. Extracts (PJ and RN) containing 50% glycerol were found to be stable, retaining more than 50% activity, even when stored at 55 degrees C for 40 days, while extracts without glycerol lost more than 75% of their allergenic activity. However, addition of glycerol did not change the stability of wheat dust allergenic extract. The present findings indicate that allergenic extracts behave differently when stored. Hence, the stability of each extract should be determined individually.

Allergens↗
PubMed1992

Intussuscepting ileal hemangioma with perforation.

A rare case of solitary intussuscepting capillary hemangioma in the distal ileum with perforation and peritonitis is presented. The diagnosis was made only at surgery for presumed acute intestinal obstruction.

Adult↗
PubMed1991

Heat aggregation studies of phycobilisomes, ferritin, insulin, and immunoglobulin by dynamic light scattering.

Dynamic laser light scattering studies on the heat aggregation behavior of phycobilisomes (PBS), ferritin, insulin, and immunoglobulin (IgG) in dilute aqueous solutions has been reported. Except for PBS, results are reported for heat aggregation trends in these proteins for three different pH environments (4.0, 7.5, 9.1). For PBS, studies were performed only in the neutral buffer medium (pH 7.5). The experiments were performed in the very dilute concentration regime (between 0.23 and 1.8 gL-1). For all these samples heat aggregation and dissociation trends were found to be linear with temperature. Upon temperature reversal (self-cooling), hysteresis-like behavior observed in insulin was found to be predominantly large at pH 7.5. PBS, ferritin, and IgG showed no such behavior at any of three pH values, and retraced their path of aggregation while dissociating on temperature reversal. Heat aggregation and dissociation processes in ferritin were found to be independent of pH. The IgG samples showed smooth aggregation tendency only up to 35 degrees C in the buffer media pH 4.0 and 9.1, whereas for pH 7.0 the same could be observed until 60 degrees C. Low polydispersity in the correlation spectra was observed in case of all these samples.

Ferritins↗
PubMed1991

Elimination of eggplant mottled crinkle virus using virazole in explant cultures of Solanum melongena L.

Virazole (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide; 100 and 150 mg/l) incorporated into brinjal explant culture medium induced in complete elimination of eggplant mottled crinkle virus - Indian isolate (EMCV-1) from infected explant cultures of S. melongena L. and production of virus free plant progeny. Acridine orange and ethidium bromide (150 ml/l) were also potent antiviral agents to some extent.

Plant Viruses↗
PubMed1990

Antifertility effects of leaf extracts of some plants in male rats.

Ethanolic leaf extracts of different local folklore plants (Azadirachta indica, Beaumontia grandiflora, Chordia dichotoma, Casiarea tomentosa, Diospyros embryopteris, Milletia auriculata and Melia azedarach) were investigated for antifertility effects on male rats in oral doses of 100 mg/kg daily for 21 days. Though, none of these extracts interfered with spermatogenesis, anti-implantational and abortifacient effects were observed in females mated by the males fed with leaf extracts of A. indica and C. dichotoma. Leaf extract of B. grandiflora besides having anti-implantational and abortifacient effects, had luteolytic effects. Abolition of libido in 100% males by leaf extracts of D. embryopteris and M. azedarach and in 60% of males by extract of C. tomentosa preclude these plants for antifertility use.

Animals↗
PubMed1977

A study of the efficacy of typhoid vaccine in inducing humoral and cell-mediated immune responses in human volunteers.

The nature of protective immunity against typhoid fever in man is not at present well understood. Work on animal models and earlier studies from this laboratory indicate an important protective role for cellular immunity. The present work attempts to study the efficacy of the conventional typhoid vaccine in inducing specific cellular and humoral immune responses. The study on fifty-eight new army recruits and thirty-one civilian volunteers showed adequate humoral responses after vaccination. However, vaccination failed to induce a significant cellular immune response. In addition, a transient suppression of cellular immunity was observed in the immediate post-vaccination period in ten subjects who possessed natural cellular immunity before vaccination. These findings indicate the need for improving the typhoid vaccine so that it will induce cellular immunity as well as a humoral response. It also points to the necessity for obtaining detailed knowledge of the post-vaccination anergy as it could be important in timing public health programmes.

Antibody Formation↗