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Biomedical subjects

V Kumar

Publications and source records attributed to V Kumar.

At least 91 records · Page 5Linked to original sources
PubMed1996

The role of Ly49A and 5E6(Ly49C) molecules in hybrid resistance mediated by murine natural killer cells against normal T cell blasts.

We address the mechanism of hybrid resistance (HR) in vitro using NK effector cells and target lymphoblasts from H-2b, H-2d, and H-2b/d mice. The 5E6 (Ly49C)+ subset of F1 NK cells lyse BALB/c (H-2d) but not B6 (H-2b) targets unless either anti-5E6 or anti-H-2Kb MAbs are present. H-2Dd transgenic B6 (D8) targets are not susceptible to F1 Ly49A+ effectors. Furthermore, 5E6+ Ly49A+ F1 effectors lyse B6 and BALB/c targets only in the presence of anti-5E6 and anti-Ly49A MAbs, respectively. Thus, recognition of H-2Kb by 5E6 and H-2Dd by Ly49A transduce independent inhibitory signals. Moreover, anti-5E6 MAbs enable 5E6+ BALB/c NK cells to lyse (BALB/c x B6)F1 targets. These data support the "missing self" and not the "hemopoietic histocompatibility antigen" hypothesis for HR. In addition, 5E6+ NK cells from BALB/c and BALB.B, but not B6 or (BALB/c x B6)F1, mice receive negative signals from both H-2d and Kb class I antigens. Thus, allelic differences in 5E6 (C57BL versus BALB) may regulate recognition events by NK cells.

Alleles↗
PubMed1996

Ventriculo-peritoneal shunt requirement in children with posterior fossa tumours: an 11-year audit.

The authors reviewed 175 paediatric patients with posterior fossa tumours treated at the Hospital for Sick Children at Great Ormond Street, London, between 1983 and 1993, in an attempt to determine the requirement for shunt procedures in these children. The age of the patient population ranged from 4 months to 14 years 6 months. The factors evaluated included age at diagnosis, tumour type, extent of surgical resection, and the presence of CSF leak and/or infection. Shunt placement was required postoperatively in 18.9% of patients. Age of the patient was felt to be a significant factor in the need for shunt placement. Tumour type and completeness of tumour excision were also felt to be significant factors affecting the need for post-operative shunt insertion.

Adolescent↗
PubMed1996

Integrated genetic map of Anopheles gambiae: use of RAPD polymorphisms for genetic, cytogenetic and STS landmarks.

Randomly amplified polymorphic DNA (RAPD) markers have been integrated in the genetic and cytogenetic maps of the malaria vector mosquito, Anopheles gambiae. Fifteen of these markers were mapped by recombination, relative to microsatellite markers that had been mapped previously. Thirty-four gel-purified RAPD bands were cloned and sequenced, generating sequence tagged sites (STSs) that can be used as entry points to the A. gambiae genome. Thirty one of these STSs were localized on nurse cell polytene chromosomes through their unique hybridization signal in in situ hybridization experiments. Five STSs map close to the breakpoints of polymorphic inversions, which are notable features of the Anopheles genome. The usefulness and limitations of this integrated mosquito map are discussed.

Animals↗
PubMed1996

Celiac disease and hypoparathyroidism: cross-reaction of endomysial antibodies with parathyroid tissue.

Celiac disease (CD) is a gluten-sensitive enteropathy characterized by the presence of serum antibodies to endomysial reticulin and gliadin antigens. CD has been associated with various autoimmune endocrine disorders, such as diabetes. We report a rare case of idiopathic hypoparathyroidism with coexistent CD characterized by the presence of serum autoantibodies. Studies were conducted to determine the specificities of these autoantibodies and to localize the antibody binding sites by indirect immunofluorescence and immunoelectron microscopy. Sera from a patient with idiopathic hypoparathyroidism and CD and from two patients with CD alone were tested by indirect immunofluorescence for autoantibodies to parathyroid and endomysial antigens. The specificities of the antibody reactions were determined by testing the sera before and after absorption with monkey stomach tissue. In addition, immunoelectron microscopic studies were performed to determine the localization of the endomysial antigen. Indirect-immunofluorescence studies on the patient's serum were positive with the parathyroid as well as the endomysial substrate. Similar reactions were also observed with the sera of endomysial antibody-positive patients with CD. Absorption of the sera with monkey stomach powder, which is known to have the endomysial antigen, abolished the antibody activities on both the endomysial substrate and the parathyroid tissue. Immunoelectron microscopic studies showed that endomysial antibody activity was associated with antigens localized on the myocyte plasma membrane and in the intercellular spaces. Thus, reactions of the patient's serum with the parathyroid tissue were due to endomysial antibodies and were not parathyroid specific as in patients with idiopathic hypoparathyroidism who did not have coexistent CD. In conclusion, indirect-immunofluorescence tests on parathyroid tissue detect not only tissue-specific antibodies but also cross-reactive antibodies, and this should be taken into consideration when these tests are performed.

Autoantibodies↗
PubMed1996

Paediatricians' knowledge of cardiac arrest guidelines.

A telephone questionnaire was undertaken on middle grade trainee paediatricians to test their knowledge of European Resuscitation Council guidelines. Fifty seven responded of whom only 15 (26%) offered a correct sequence of management for asystole and eight (14%) failed to identify adrenaline in their management. For ventricular fibrillation only 18/57 (32%) identified a correct sequence and very poor specific knowledge was identified. Paediatricians will under perform in the event of cardiac arrest in children without improved training in resuscitation.

Child↗
PubMed1996

Neuroticism in a family practice population in India.

This study was conducted to assess the prevalence of neuroticism and its correlation with the various sociodemographic factors and presenting complaints among patients attending a family practice outpatient clinic. One hundred and forty two consecutive patients attending the outpatient clinic were administered PGI Health Questionnaire N2. Higher incidence of neuroticism was observed in middle age group population, in females (especially housewives), unskilled workers, patients with lower educational status and those belonging to small and nuclear families. A significant number of such patients had presented with vague symptoms, were visiting the clinics frequently and had associated chronic diseases. The results suggest that patients visiting the family practice clinics frequently with multiple somatic complaints with no suggested organic basis should undergo an in-depth psychiatric evaluation.

Adult↗
PubMed1996

A novel method for studying preadipocyte differentiation in vitro.

In vitro differentiation of rat preadipocytes has typically been induced in medium supplemented with pharmacological concentrations of hormonal mixtures. These conditions probably do not reflect the milieu within adipose tissue in vivo. We have developed a new method for inducing differentiation of preadipocytes using culture medium which has been conditioned by isolated adipocytes (ACM). In the presence of ACM, 70%-80% of test preadipocytes contained lipid inclusions compared to < 5% of control. When differentiation was assessed by assay of glycerol-3-phosphate dehydrogenase activity, ACM activity was shown to be reproducible and the consistency of response to ACM by different pools of preadipocytes was comparable to that induced by standard differentiation procedures. We have also demonstrated that the adipogenic activity of ACM may not depend on prostaglandin secretion by adipocytes. We propose that use of paracrine factors produced by components of adipose tissue provides a new approach to preadipocyte differentiation induction which may more closely reproduce the adipose tissue environment.

Adenosine↗
PubMed1996

Culturally appropriate measures for monitoring child development at family and community level: a WHO collaborative study.

Culturally appropriate techniques for monitoring child psychosocial development were prepared and tested in China, India and Thailand on a total of 28,139 children. This is the largest study of its kind ever undertaken. Representative groups aged between birth and 6 years were examined and the results were used to produce national development standards-separately for rural and urban children in China and India, and for all children combined in Thailand-which are considered to be more satisfactory than foreign-based standards. In each country, between 13 and 19 key milestones of psychosocial development were selected for a simplified developmental screening operation and these have been incorporated on a home-based record of a child's growth and development. Between 35 and 67 tests have been devised in each country to test the children at first-referral level.

Child↗
PubMed1996

Pancreatic sarcoidosis.

Sarcoidosis affects every organ in the body; the most frequently involved structures are the lung, lymph nodes, liver, spleen, eyes, joints and heart. Gastrointestinal system affliction is uncommon. The pancreas is rarely affected by sarcoidosis. A review of the literature revealed only 13 patients with biopsy proven granulomas in pancreas or peripancreatic nodes. In a review of all autopsies performed between 1950 and 1993 at Los Angeles County + University of Southern California School of Medicine, Los Angeles, USA, the authors found one patient with pancreatic and 5 with peripancreatic lymph node granuloma. The authors also describe three previously unreported cases of pancreatic sarcoidosis. From the discussion, a clinically useful and pragmatic profile of pancreatic sarcoidosis emerges. Two thirds of the patients with pancreatic sarcoidosis have abdominal pain, and three quarters of them have bilateral hilar adenopathy. The occurrence of abdominal pain in a woman with bilateral hilar adenopathy with or without pulmonary infiltration should lead one to think of pancreatic sarcoidosis. The diagnosis should be established by a tissue biopsy because the laboratory and radiographic techniques do not differentiate pancreatic sarcoidosis from other inflammatory and malignant disorders of the pancreas. The prognosis of pancreatic sarcoidosis is good.

Adult↗
PubMed1996

Median nerve somatosensory evoked potentials in rubber factory workers.

Somatosensory evoked potentials (SEPs) on median nerve stimulation were studied in 38 rubber factory workers to detect possible subclinical impairments in the somatosensory pathway as a result of exposure to rubber factory chemicals. Results showed trend towards the prolongation of latencies of all the major peaks of SEP such as P1, N1, P2, N2, P3, N3 in exposed workers besides changes in peak to peak amplitudes (higher P1-N1 and lower N2-P3). These changes may be attributed to synergistic action of solvents and other rubber factory chemicals on the generators of SEPs located higher up at the thalamo-cortical level.

Adolescent↗
PubMed1996

Brainstem auditory evoked potentials (BAEPs) in tobacco smokers.

Brainstem auditory evoked potentials (BAEPs) were studied in 10 chronic male tobacco smokes (average age 26.55 years) with history of smoking 3 to 14 years to detect early subclinical impairments in auditory pathway. The values of BAEPs were compared with those of 28 age matched normal male non-smokers (control). The results revealed significant prolongation of latencies of wave I and III indicating that conductivity of sensory impulse along acoustic nerve and pons is affected in chronic smokers which may be attributed to adverse effect on myelination by nicotine and toluene present in tobacco smoke.

Adult↗
PubMed1996

Melatonin: a master hormone and a candidate for universal panacea.

The molecule of melatonin seems to have been evolutionarily conserved. Its presence has been demonstrated in almost all groups of organisms, from plants, protozoa to people. During evolution, melatonin is claimed to have mediated dark adaptation. The universal presence of melatonin may be because it is lipophilic in nature which enables it to cross all biological (lipid membrane) barriers and to diffuse into every compartment of the cell, and because it serves as an antioxidant and is used as a free radical scavenger. In vertebrates, the pineal gland is the single largest source of melatonin production although, especially in non-mammalian vertebrates, other organs (e.g. retina, harderian gland etc.) may contribute significantly to the blood melatonin levels. In invertebrates, on the other hand, the pineal gland is absent and, therefore, melatonin secretion is clearly derived from another source(s). Regardless of the site of synthesis and the nature of organisms (diurnal, nocturnal or crepuscular), melatonin is secreted in the night and melatonin biosynthetic pathway remains essentially the same. Tryptophan, an amino acid derived from dietary sources, undergoes a series of enzymatic reactions to produce melatonin. The rhythm in melatonin secretion is generated endogenously by the circadian pacemaker(s) in the suprachiasmatic nuclei (SCN), and regulated by environmental light:dark cycle. Melatonin through its action on the SCN synchronizes disrupted or free-running circadian rhythms, and regulates a variety of daily and seasonal changes in the physiology and behaviour of animals. Emerging scientific evidence for the role of melatonin as therapeutic agent in the treatment of circadian rhythm-associated sleep disorders in persons having normal social working hours and shift workers, in jet lag, in immunological functions etc. have considerably increased interest in this hormone molecule. The role of melatonin in organisms physiology has now been widely recognized, and the wealth of information accumulated in the past two decades indicate it to be the best hormone candidate to be investigated for a universal panacea.

Animals↗