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Biomedical subjects

A Sinha

Publications and source records attributed to A Sinha.

At least 91 records · Page 5Linked to original sources
PubMed1999

Verapamil prolongs atrial fibrillation by evoking an intense sympathetic neurohumoral effect.

BACKGROUND: Verapamil is an effective drug to slow ventricular rate in atrial fibrillation (AF). Clinically, however, i.v. verapamil enhances AF despite experimental evidence suggesting favorable effects of the drug on AF-induced electrical remodeling of the atria. METHODS AND RESULTS: To clarify this controversy, i.v. verapamil's effects were determined in 41 anesthetized dogs, including 6 after beta-blockade. Intravenous verapamil (0.20 mg/kg, bolus, and 0.20 mg/kg/h, infusion) increased the duration of AF (induced by a single extrastimulus), from 19 +/- 6 to 130 +/- 24 s, P < 0.001, and slowed its ventricular response, from 246 +/- 25 to 110 +/- 15 min-1, P < 0.001. Mean aortic pressure, P = 0.002, and systemic vascular resistance, P < 0.035, decreased, and mean right atrial pressure increased, P < 0.001. Plasma norepinephrine concentration increased by 502 +/- 83 pg/mL, P < 0.001, plasma epinephrine concentration by 804 +/- 206 pg/mL, P = 0.002, and plasma total catecholamine concentration by 1606 +/- 366 pg/mL, P = 0.001. Prolongation of AF was related to an increase in mean right atrial pressure, R = 0.49, P = 0.014, right atrial wall tension, R = 0.45, P = 0.044, and plasma norepinephrine concentration, R = 0.83, P < 0.001, with plasma norepinephrine concentration remaining as an independent predictor of AF lengthening on multivariable analysis. In the presence of beta-blockade, verapamil produced comparable or more exaggerated hemodynamic effects, but it did not promote AF. CONCLUSION: The prolongation of AF by verapamil can be related directly to the intense sympathetic neurohumoral effect that occurs following the drug's administration.

Animals↗
PubMed1999

Clinico-epidemiological study of hospitalized cases of severe leptospirosis.

In an attempt to understand the clinical spectrum and pathological and biochemical abnormalities and their prognostic importance in leptospirosis, a prospective study was carried out in Port Blair during September 1996 to August 1997. Out of 80 patients suspected to have leptospirosis, 58 were proved to have current leptospiral infection using serological tests and among these, 14 died giving a case fatality rate of 24.1 per cent. The incidence of the disease showed two separate peaks roughly coinciding with the paddy sowing and harvesting season and the majority of the patients had history of exposure to wet and water logged environment prior to the attack of the disease. The disease presented as two separate clinical syndromes--the hepato-renal form and the pulmonary form though some degree of overlap was present. Hepatic and renal complications occurred in 30 patients each with 26 of them having both. These generally occurred late in the course of the disease and the mortality rate was relatively low. In contrast pulmonary complication occurred quite early and the case fatality rate in those patients was very high (6.7% vs 42.9%). The other complications encountered in the current series of cases were refractory hypotension probably due to myocarditis in 40 per cent and neck stiffness and altered sensorium due to central nervous involvement in 12.1 per cent of the patients. The chances of the patients developing complications were considerably low if treated early and very few of them developed any complications after 2 days of hospitalized treatment. The early occurrence of pulmonary complications indicates a pathogenesis totally different from that responsible for the other complications.

Adolescent↗
PubMed1999

Self-organizing map (SOM) of space acceleration measurement system (SAMS) data.

In this paper, space acceleration measurement system (SAMS) data have been classified using self-organizing map (SOM) networks without any supervision; i.e., no a priori knowledge is assumed regarding input patterns belonging to a certain class. Input patterns are created on the basis of power spectral densities of SAMS data. Results for SAMS data from STS-50 and STS-57 missions are presented. Following issues are discussed in details: impact of number of neurons, global ordering of SOM weight vectors, effectiveness of a SOM in data classification, and effects of shifting time windows in the generation of input patterns. The concept of 'cascade of SOM networks' is also developed and tested. It has been found that a SOM network can successfully classify SAMS data obtained during STS-50 and STS-57 missions.

Acceleration↗
PubMed1999

Unsupervised classification of Space Acceleration Measurement System (SAMS) data using ART2-A.

The Space Acceleration Measurement System (SAMS) has been developed by NASA to monitor the microgravity acceleration environment aboard the space shuttle. The amount of data collected by a SAMS unit during a shuttle mission is in the several gigabytes range. Adaptive Resonance Theory 2-A (ART2-A), an unsupervised neural network, has been used to cluster these data and to develop cause and effect relationships among disturbances and the acceleration environment. Using input patterns formed on the basis of power spectral densities (psd), data collected from two missions, STS-050 and STS-057, have been clustered.

Acceleration↗
PubMed1998

Immunosuppressive effect of vestibulo-cerebellar lesion in rats.

Kainate lesion of the vestibulo cerebellum induces sympathetic hyperactivity, but the mechanism of immunosuppression observed as a result is not yet clarified. Here we report that vestibulo cerebellum lesioned (VCL) rats have depressed secretion of haematopoietic cytokines (bioimmunomodulator or BIM, a 12.7 kD peptide and thymosin FrV) in tissue cultures of bone marrow and thymus, respectively, compared with controls (P < 0.01). Peripheral blood leukocyte concentration, neutrophil myeloperoxydase response, T-SRBC rosette and antibody titre to sheep red blood cells (SRBC) are also significantly less, compared with control (P < 0.01). Injection of BIM (concentration 0.01 microg/g body weight) in VCL rats corrected the immunodeficiency. Partial restoration of immune competence is observed after injection of thymosin FrV (0.01 microg/g body weight) or after prolonged vestibular stimulation (18 rpm for 15 min/day for 21 days). The results indicate that the vestibular nodule (VN) through autonomic nerves (AN) can modulate the immune function of rats by regulating the secretion of cytokines from bone marrow and thymus.

Animals↗
PubMed1998

Primers of glycosaminoglycan biosynthesis from Peruvian rain forest plants.

We have developed a rapid, high throughput screening assay for compounds that alter the assembly of glycosaminoglycan chains in Chinese hamster ovary cells. The assay uses autoradiography to measure the binding of newly synthesized [35S]proteoglycans and [35S]glycosaminoglycans to a positively charged membrane. Screening over 1000 extracts from a random plant collection obtained from the Amazon rain forest yielded five plants that stimulated glycosaminoglycan assembly in both wild-type cells and a mutant cell line defective in xylosyltransferase (the first committed enzyme involved in glycosaminoglycan biosynthesis). Fractionation of an extract of Maieta guianensis by silica gel and reverse-phase chromatography yielded two pure compounds with stimulatory activity. Spectroscopic analysis by NMR and mass spectrometry revealed that the active principles were xylosides of dimethylated ellagic acid. One of the compounds also contained a galloyl group at C-3 of the xylose moiety. These findings suggest that plants and other natural products may be a source of agents that can potentially alter glycosaminoglycan and proteoglycan formation in animal cells.

Animals↗
PubMed1998

Knowledge acquired and decisions made: triadic interactions during allogrooming in wild bonnet macaques, Macaca radiata.

The pressures of developing and maintaining intricate social relationships may have led to the evolution of enhanced cognitive abilities in many nonhuman primates. Knowledge of the dominance ranks and social relationships of other individuals, in particular, is important in evaluating one's position in the rank hierarchy and affiliative networks. Triadic interactions offer an excellent opportunity to examine whether decisions are taken by individuals on the basis of such knowledge. Allogrooming supplants among wild female bonnet macaques (macaca radiata) usually involved the subordinate female of a grooming dyad retreating at the approach of a female dominant to both members of the dyad. In a few exceptional cases, however, the dominant member of the dyad retreated; simple non-cognitive hypotheses involving dyadic rank differences and agonistic relationships failed to explain this phenomenon. Instead, retreat by the dominant individual was positively correlated with the social attractiveness of her subordinate companion (as measured by the duration of grooming received by the latter from other females in the troop). This suggests that not only does an individual evaluate relationships among other females, but does so on the basis of the amount of grooming received by them. Similarly, the frequency of approaches received by any female was correlated with her social attractiveness when she was the dominant member of the dyad, but not when she was the subordinate. This indicated that approaching females might be aware of the relative dominance ranks of the two allogrooming individuals. In logistic regression analyses, the probability of any individual retreating was found to be influenced more by her knowledge of her rank difference with both the other interactants, rather than by their absolute ranks. Moreover, information about social attractiveness appeared to be used in terms of correlated dominance ranks. The nature of knowledge acquired by bonnet macaque females may thus be egotistical in that other individuals are evaluated relative to oneself, integrative in that information about all other interactants is used simultaneously, and hierarchical in the ability to preferentially use certain categories of knowledge for the storage of related information from other domains.

Aggression↗
PubMed1998

Mutation of the sialyltransferase S-sialylmotif alters the kinetics of the donor and acceptor substrates.

Protein sequence analysis of the cloned sialyltransferase gene family has revealed the presence of two conserved protein motifs in the middle of the lumenal catalytic domain, termed L-sialylmotif and S-sialylmotif. In our previous study (Datta, A. K., and Paulson, J. C. (1995) J. Biol. Chem. 270, 1497-1500) the larger L-sialylmotif of ST6Gal I was analyzed by site-directed mutagenesis, which provided evidence that it participates in the binding of the CMP-NeuAc, a common donor substrate for all the sialyltransferases. However, none of the mutants tested in this motif had any significant effect on their binding affinities toward the acceptor substrate asialo alpha1-acid glycoprotein. In this study, we have investigated the role of the S-sialylmotif of the same enzyme ST6Gal I. In total, nine mutants have been constructed by changing the conserved amino acids of this motif to mostly alanine by site-directed mutagenesis. Kinetic analysis for the mutants which retained sialyltransferase activity showed that the mutations in the S-sialylmotif caused a change of Km values for both the donor and the acceptor substrates. Our results indicated that this motif participates in the binding of both the substrates. A sequence homology search also supported this finding, which showed that the downstream amino acid sequence of the S-sialylmotif is conserved for each subgroup of this enzyme family, indicating its association with the acceptor substrate.

Amino Acid Sequence↗
PubMed1998

Latex glove allergy among hospital employees: a study in the north-west of England.

The frequency of use and duration of wearing latex gloves among hospital employees has increased due to concerns about AIDS and hepatitis. In many countries there is increased consciousness about latex sensitization. In the UK, the Medical Device Agency has been monitoring latex allergy for a number of years but has not found any conclusive evidence of any significant problem. We report following a detailed questionnaire study in two hospitals in the north-west of England. A total of 1,827 members of staff were questioned about latex allergy at work. One hundred and twenty-four (7%) of these hospital employees had experienced symptoms strongly suggestive of latex allergy. Of this group, 56 had a-RAST test (IgE specific to latex), which was positive in seven (12.5%). There was a history of atopy in 31%, and a family history of atopy in 17% of the individuals. As a result of the study it was found that 17% (21 of the affected individuals) had already changed their working practice by using latex-free gloves. We were able to increase awareness of latex allergy within the hospitals. Both individuals and health care organizations need to be aware of the problem and hospital organizations should encourage staff to seek guidance to address the problem and, if necessary, to take appropriate measures to improve working practices. Practical guidelines are given with regard to identifying the problem and glove use for hospital staff.

Adult↗
PubMed1998

Zinc supplementation reduces the incidence of acute lower respiratory infections in infants and preschool children: a double-blind, controlled trial.

BACKGROUND: Increased acute lower respiratory infection incidence, severity, and mortality are associated with malnutrition, and reduced immunological competence may be a mechanism for this association. Because zinc deficiency results in impaired immunocompetence and zinc supplementation improves immune status, we hypothesized that zinc deficiency is associated with increased incidence and severity of acute lower respiratory infection. METHODS: We evaluated the effect of daily supplementation with 10 mg of elemental zinc on the incidence and prevalence of acute lower respiratory infection in a double-blind, randomized, controlled trial in 609 children (zinc, n = 298; control, n = 311) 6 to 35 months of age. Supplementation and morbidity surveillance were done for 6 months. RESULTS: After 120 days of supplementation, the percentage of children with plasma zinc concentrations <60 microg/dL decreased from 35.6% to 11.6% in the zinc group, whereas in the control group it increased from 36.8% to 43.6%. Zinc-supplemented children had 0.19 acute lower respiratory infection episodes/child/year compared with 0.35 episodes/child/year in the control children. After correction for correlation of data using generalized estimating equation regression methods, there was a reduction of 45% (95% confidence interval, 10% to 67%) in the incidence of acute lower respiratory infections in zinc-supplemented children. CONCLUSIONS: A dietary zinc supplement resulted in a significant reduction in respiratory morbidity in preschool children. These findings suggest that interventions to improve zinc intake will improve the health and survival of children in developing countries.

Child, Preschool↗
PubMed1997

Benign necrotizing osteitis of the external auditory meatus.

Benign necrotizing osteitis of the external auditory meatus is a rare condition which occurs in non-diabetic healthy people. The aetiology of the necrotic process with the formation of sequestrum in the bony external meatus is unknown. It is important to differentiate this benign process from malignant otitis externa and radionecrosis of the temporal bone as the management of these conditions differs. We present two cases, one managed surgically and the other medically, and review the literature. Immediate surgical excision of the sequestrum is advocated instead of long-term medical therapy and waiting for it to separate spontaneously.

Adult↗
PubMed1997

Efficacy of zinc supplementation in reducing the incidence and prevalence of acute diarrhea--a community-based, double-blind, controlled trial.

A community-based, double-blind, randomized trial was conducted in a population of low socioeconomic status in urban India to determine whether daily zinc supplementation reduces the incidence and prevalence of acute diarrhea, especially in those with zinc deficiency. Children 6-35 mo of age were randomly assigned to zinc (n = 286) and control (n = 293) groups and received a supplement daily for 6 mo. Zinc gluconate (10 mg elemental Zn) was given, with both zinc and control groups also receiving multivitamins. The primary outcome measures determined by home visits every fifth day and physician examinations were the number of acute diarrheal episodes (incidence) and total diarrheal days (prevalence). Zinc supplementation had no effect in children 6-11 mo old. In children aged > 11 mo there was significantly less diarrhea in the zinc group. In boys > 11 mo old, supplementation resulted in a 26% (95% CI: 13%, 38%) lower diarrheal incidence and a 35% (95% CI: 20%, 50%) lower prevalence. In zinc-supplemented girls > 11 mo of age, the incidence was 17% (95% CI: 2%, 30%) lower and the prevalence was 19% (95% CI: 4%, 47%) lower. Overall, zinc supplementation resulted in a 17% (95% CI: 1%, 30%) lower diarrheal incidence in children with plasma zinc concentrations < 9.18 mumol/L at enrollment and a 33% (95% CI: 6%, 52%) lower incidence in children with concentrations < 50 mumol/L. In conclusion, zinc supplementation had a significant effect on acute diarrheal morbidity in children > 11 mo old and in children with low plasma zinc concentrations.

Acute Disease↗
PubMed1997

Study of aeroball injuries.

OBJECTIVE: To present the risks of aeroball, a new sport played by either two or four players on a trampoline court surrounded by specially constructed fabric walls, and to propose ways to increase awareness and reduce the incidence of injury, in particular, ankle injury. METHOD: A study was carried out to document the nature of aeroball related incidents, between 1991 and 1995, at Lancaster University Sports Centre. Lace-up ankle supports were introduced in April 1992, and their effect on the incidence of ankle injury was recorded. RESULTS: The lower limb received most injuries (90%), followed by the upper limb (6%), then the face (3%) and cervical spine (1%). The most common category of injuries was sprains (83%), followed by fractures (8%), contusions (5%), and dislocations (4%). The most common site of injury was the ankle (73%). It is during doubles play that injury is most likely to occur. Since the introduction of ankle supports, there has been a gradual decline in the incidence of ankle injury, 31 in 1991 to nine in 1995. CONCLUSION: Aeroball has become a popular sport, but it is not without risks. Leaflets have been produced to promote the objectives, rules, and safety of the game. Trained full-time staff should be present to explain the nature of the game. The use of prophylactic ankle stabilisers in aeroball is strongly recommended.

Adolescent↗
PubMed1997

Dupuytren's disease may extend beyond the wrist crease in continuity.

Debate continues about the origin of Dupuytren's disease, which is usually in the palm but is seen elsewhere as ectopic lesions. We describe a young patient with Dupuytren's disease extending proximal to the wrist crease in continuity with the palmar lesion. Our findings support the view that the condition starts within the palmar connective tissue, but there is no palmar aponeurosis in the forearm and the proximal extension probably started in the deep layer of the superficial fascia.

Adult↗
PubMed1997

Effect of zinc supplementation on cell-mediated immunity and lymphocyte subsets in preschool children.

OBJECTIVE: In a zinc supplementation trial (with a significant impact on diarrheal morbidity), to evaluate effect of zinc supplementation on cellular immune status before and after 120 days of supplementation. DESIGN: A double blind, randomized controlled trial with immune assessment at baseline and after 120 days on supplement. SETTING: Community based study in an urban slum population. SUBJECTS: Randomly selected children (zinc 38, control 48), had a Multitest CMI skin test at both times. In 66 children (zinc 22, control 34), proportions of CD3, CD4, CD8, CD16, CD20 cells and the CD/CD8 ratio were also estimated using a whole blood lysis method and flowcytometry. INTERVENTION: Zinc gluconate to provide elemental zinc 10 mg daily and 20 mg during diarrhea. MAIN OUTCOME RESULTS: Regarding CMI, the percentage of anergic or hypoergic children (using induration score) decreased from 67% to 47% in the zinc group, while in the control group it remained unchanged (73% vs 71%) (p = 0.05). The percentage of children deteriorating between first and second tests was significantly lower in the zinc group (13% vs 33%, p = 0.03). Regarding lymphocyte subsets, the zinc group had a significantly higher rise in the geometric means of CD3 (25%, p = 0.02), CD4 (64% p = 0.001), and CD4/CD8 ratio (73% p = 0.004) with no difference in CD8 and CD20. The rise in CD4 was significantly higher in the zinc as compared to the control group; the ratio of geometric means was 1.45 (95% CI, 1.03-2.01). CONCLUSION: Zinc supplementation improves cellular immune status, which may have been one of the mechanisms for observed impact of zinc supplementation on diarrheal morbidity.

Child, Preschool↗
PubMed1996

Effects of insulin on body composition in patients with insulin-dependent and non-insulin-dependent diabetes.

Insulin is used to control blood glucose but may have an adverse effect on the amount and distribution of fat mass and other cardiovascular risk factors. To test this hypothesis the effect of insulin therapy on blood glucose, body composition, and lipid levels was measured during 6 months in 9 patients with newly diagnosed insulin-dependent (Type 1) diabetes mellitus (IDDM) and 15 patients with non-insulin dependent (Type 2) diabetes (NIDDM) and secondary failure of therapy with oral hypoglycaemic agents. Both groups received similar daily doses of insulin (approximately 0.6 units kg-1 day-1). Glycaemic control improved during 6 months treatment in both groups, although the reduction in HbA1c was greater in IDDM (5.2 +/- 0.7%) than in NIDDM (2.0 +/- 0.4%, p < 0.001). All parameters of the lipid profile improved in IDDM but not in NIDDM. Body weight, lean mass, and fat mass, measured by dual energy x-ray absorptiometry, increased at 1 month in IDDM but not in NIDDM. By 6 months, body weight had increased more in IDDM than NIDDM (9.1 +/- 1.2 vs 3.77 +/- 0.5 kg, p < 0.01). The increase in weight was predominantly lean mass in IDDM (60.4 +/- 9.3%) and fat mass in NIDDM (59.9 +/- 8.4%). The increase in lean mass was greater in IDDM than NIDDM (5.6 +/- 1.1 vs 1.4 +/- 0.3 kg, p < 0.001). Fat mass increased by similar increments in IDDM and NIDDM (3.4 +/- 0.8 vs 2.4 +/- 0.5 kg, p = ns) and was predominantly an increase in trunk fat (IDDM: 2.3 +/- 0.6 kg, NIDDM: 2.0 +/- 0.4 kg, p = ns). The central/peripheral fat mass ratio prior to treatment was lower in IDDM than NIDDM (0.64 +/- 0.05 vs 1.09 +/- 0.09, p < 0.01) and then increased in IDDM by 0.32 +/- 0.15 (p = 0.07) and in NIDDM by 0.22 +/- 0.06 (p < 0.001). In conclusion, insulin therapy is associated with weight gain in both IDDM and NIDDM. In the former, weight gain reflects increases in lean mass whereas in NIDDM it reflects an increase in trunk fat mass. It remains to be determined whether this trend to central obesity partly offsets other benefits of insulin therapy in NIDDM.

Adipose Tissue↗
PubMed1996

Field trial of billings ovulation method of natural family planning.

There are couples with unmet family planning needs and couples who do not use any modern method, yet they desire to space or avoid pregnancies. Many of them look for safe and effective options like the natural family planning methods. The Billings Ovulation Method based on single index cervical mucus parameter is one such option. The present multicentre trial conducted in India has shown an encouraging use-effectiveness of the method, indicating method failure as low as 1.5 +/- 0.3 and use-failure 15.9 +/- 0.8 per 100 users at 21 months. The method continuation rates have also been as high as 88.3/100 users at 6 months and 52.0/100 users at 21 months.

Adult↗