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Biomedical subjects

A Kumar

Publications and source records attributed to A Kumar.

At least 181 records · Page 10Linked to original sources
PubMed1992

Extreme heterogeneity of Ty1-copia group retrotransposons in plants.

We have used the polymerase chain reaction to analyse Ty1-copia group retrotransposons of flowering plants. All eight species studied contain reverse transcriptase fragments from Ty1-copia group retrotransposons. Sequence analysis of 31 subcloned fragments from potato reveals that each is different from the others, with predicted amino acid diversities between individual fragments varying between 5% and 75%. Such sequence heterogeneity within a single species contrasts strongly with the limited diversity seen in such retrotransposons in yeast and Drosophila. The fragments from the other seven plant species examined are also heterogeneous, both within and between species, showing that this is a general property of this transposon group in plants. Phylogenetic analysis of all these sequences reveals that many of them fall into subgroups which span species boundaries, such that the closest homologue of one sequence is often from a different species. We suggest that both vertical transmission of Ty1-copia group retrotransposons within plant lineages and horizontal transmission between different species have played roles in the evolution of Ty1-copia group retrotransposons in flowering plants.

Amino Acid Sequence↗
PubMed1992

Survival in patients with systemic lupus erythematosus in India.

Survival in patients with systemic lupus erythematosus (SLE) in developed countries has improved considerably over the last 2 decades. In India, however, survival in patients with SLE reported 5 years ago from this tertiary referral centre was very poor. The present study was conducted to examine trends, if any, towards improvement in the survival of patients with SLE attending the same centre during the period 1981-1990. No statistically significant change in survival was noted. It appears that improvement in the survival of SLE patients would require an overall improvement in the standard of medical care in India.

Adult↗
PubMed1992

Spinal anaesthesia with lidocaine 2% for caesarean section.

Spinal anaesthesia with 2, 2.5 or 3 ml of glucose-free lidocaine 2% was studied in 50 patients undergoing Caesarean section. Onset time, cephalad spread of analgesia, quality of analgesia, muscle relaxation, the cardiovascular effects and duration of analgesia and motor block were assessed. Reliable anaesthesia was provided with 2.5 and 3 ml while 2 ml of 2% lidocaine was insufficient. Onset time varied between 5.5 to 6 min and maximum cephalad spread was achieved in 10-15 min. The mean maximum extent of sensory analgesia was higher after 2.5 ml (T4.1) and 3 ml (T3.6) than after 2 ml (T7) (P < 0.001). Complete motor block was achieved in all the patients. The mean duration of sensory block was 123 +/- 6.23 min (2 ml) to 126 +/- 7.53 min (2.5 and 3 ml). The mean duration of motor block in 2.5 and 3 ml groups was higher (P < 0.001) than in the 2 ml group and was correlated with the dose of lidocaine (P < 0.05). Hypotension (SBP < 100 mmHg) was noted in 10% (n = 5) of patients in whom the cephalad spread of analgesia was also higher. All the neonates had an apgar score of 7 or more at 1 min. These results suggest that 2.5 to 3 ml of 2% lidocaine provides satisfactory anaesthesia for Caesarean section.

Adult↗
PubMed1992

Arterial blood nicotine concentration and coronary vasoconstrictive effect of low-nicotine cigarette smoking.

Low-nicotine cigarettes have been advertised to the public as less harmful to the cardiovascular system. We studied the effects of smoking two low-nicotine cigarettes on arterial and venous blood nicotine levels, hemodynamics, and coronary vascular tone in 12 patients referred for diagnostic coronary arteriography. All were chronic smokers as evidenced by their elevated baseline arterial and venous cotinine blood levels (139 +/- 30 ng/ml and 155 +/- 34 ng/ml, respectively). High-resolution coronary angiograms were evaluated "blindly" before and after smoking. An electronic caliper was used to measure the diameter of disease-free coronary segments of the left anterior descending and circumflex arteries. Arterial nicotine levels rose from 5 +/- 1 ng/ml at baseline to 37 +/- 7 ng/ml (p less than 0.01) after the first cigarette was smoked and to 45 +/- 8 ng/ml (p less than 0.01) after the second cigarette. Venous nicotine levels rose from 8 +/- 2 ng at baseline to 15 +/- 3 ng/ml (p less than 0.05) after the first cigarette and to 20 +/- 3 ng/ml (p less than 0.01) after the second cigarette. After the first cigarette heart rate increased 8 +/- 2 beats/min (p less than 0.003) and double product 1229 +/- 400 beats/min x mm Hg (p less than 0.02). Compared to baseline values, after the second cigarette heart rate increased 9 +/- 1 beats/min (p less than 0.001) and double product 1767 +/- 486 beats/min x mm Hg (p less than 0.01). Systolic, diastolic, and mean blood pressure did not change significantly after either the first or second cigarette.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1992

Prevalence and predictors of rhabdomyolysis in patients with hypophosphatemia.

PURPOSE: We undertook this study to determine the prevalence and predictors of rhabdomyolysis in the hypophosphatemic state. PATIENTS AND METHODS: To identify patients with hypophosphatemia, we reviewed medical admissions for the period of January through December 1989. The hypophosphatemic state was considered whenever the serum phosphate was less than or equal to 2.0 mg/dL. Rhabdomyolysis secondary to hypophosphatemia was defined when serum creatine kinase levels were greater than or equal to 224 IU/L; it occurred within 72 hours of the hypophosphatemic episode; and it subsequently normalized. Patients who had any other independent etiology for rhabdomyolysis were excluded. Clinical and biochemical characteristics of patients with rhabdomyolysis (Group I) and patients without rhabdomyolysis (Group II) were compared. Variables that predicted rhabdomyolysis in hypophosphatemia were identified by stepwise logistic regression using a backward elimination procedure. RESULTS: One hundred twenty-nine patients were found to have hypophosphatemia. Forty-six (Group I) of 129 patients (36%) showed biochemical evidence of rhabdomyolysis. There was no difference in serum phosphate and potassium concentrations between Group I and Group II patients. Patients in Group I showed higher values for serum osmolality (p less than 0.05), serum glutamic oxaloacetic transaminase (p less than 0.001), chloride (p less than 0.01), and blood urea nitrogen (less than 0.05) when compared with Group II patients. When biochemical profiles of patients with rhabdomyolysis were evaluated on the day of their peak creatine kinase level, only 16 patients were hypophosphatemic, and the majority of patients showed a transient increase in serum phosphate levels because of ongoing muscle cell injury. Of 17 potential predictors, six variables emerged including sodium, chloride, glucose, blood urea nitrogen, uric acid, and osmolality. These variables provided high sensitivity (0.88) as well as moderate specificity (0.79) for predicting the occurrence of rhabdomyolysis in hypophosphatemia. CONCLUSION: We conclude that rhabdomyolysis commonly occurs in the hypophosphatemic state and that at times severe hypophosphatemia as an etiology may be masked because of ongoing rhabdomyolysis. Serum sodium, chloride, glucose, blood urea nitrogen, uric acid, and osmolality have a predictive role for the occurrence of rhabdomyolysis in the hypophosphatemic state that shows a high specificity and a moderate sensitivity.

Adult↗
PubMed1992

Resolution of dihydroxyeicosanoates and of dihydroxyeicosatrienoates by chiral phase chromatography.

A chromatographic method is described for the direct enantiomeric characterization of 5,6-, 8,9-, 11,12-, and 14,15-vic-dihydroxyeicosatrienoic acids (DHETs), metabolites of the cytochrome P-450 arachidonate epoxygenase pathway, and of their corresponding saturated vic-dihydroxyeicosanoic acids. Following esterification, the individual methyl or pentafluorobenzyl esters are resolved by chiral-phase chromatography utilizing a Chiralcel OC or OD column. This methodology will find analytical and preparative applications since it is simple and efficient and preserves, intact, the diol functionality.

8,11,14-Eicosatrienoic Acid↗
PubMed1992

The effect of cimetidine on lymphocyte subpopulations in vivo in experimental mice.

The effects of cimetidine, an H2 receptor antagonist, on subpopulation of splenic lymphocytes were studied in mice. Cimetidine (50 mg/kg) was given to groups of mice by intraperitoneal injection. The splenic mononuclear cells from treated and control animals were evaluated for relative number of lymphocyte subpopulations (i.e. LYT1, LYT2, L3T4 and GAM cells) by flow cytometry. The percentages of LYT2 cells (suppressor equivalent) were significantly lower (5.5 vs 12.0%) in mice who were treated with cimetidine vs control animals. The percentages of L3T4 (helper equivalent) were not statistically different in any of the experimental groups.

Animals↗
PubMed1992

Influenza B virus infection associated with non-bacterial septic shock-like illness.

We report the details of four children aged between 6 months and 5.5 years who had underlying chronic disease and who developed life-threatening illness in association with influenza virus B infection. Influenza has received relatively little attention, yet its morbidity and mortality in children can be considerable. This report emphasises the need to vaccinate the population groups at high risk, such as children with cardiovascular disorders, chronic bronchopulmonary, metabolic and renal disease and chronic neurological disorders.

Child, Preschool↗
PubMed1992

Comparison of immune responses to a native viral antigen and a synthetic peptide derived from it: implications for vaccine development.

Murine immune responses to the hepatitis B surface antigen (HBsAg) and a synthetic peptide derived from it were compared at the humoral level. Six of nine strains used responded to either peptide or HBsAg, though restriction profiles were not superimposable. Two of three strains non-responsive to HBsAg produced an antibody response on immunization with peptide which was cross-reactive with both peptide and HBsAg. In in vitro lymphocyte stimulation assays, lymphocyte from all six peptide-immunized mouse strains could be induced to proliferate on challenge with HBsAg. However, of the HBsAg-immunized groups, lymphocytes from only three of six responder strains proliferated on in vitro HBsAg challenge. Cumulatively, these results suggest that a vaccine formulation that includes both protein antigens and synthetic peptides derived from these proteins may be more effective at eliciting an immune response in a broader cross-section of target population.

Animals↗
PubMed1992

Postnatal laminar development of cholinergic receptors, protein kinase C and dihydropyridine-sensitive calcium antagonist binding in rat visual cortex. Effect of visual deprivation.

The postnatal ontogeny of 3H-pirenzepine and 3H-oxotremorine-M binding to M1-and M2-muscarinic acetylcholine receptors, respectively, as well as 3H-nicotine binding to neuronal nicotinic acetylcholine receptors, 3H-phorbol-12,13-dibutyrate binding to protein kinase C and 3H-PN200-110 binding to dihydropyridine-sensitive calcium channels was studied in individual layers of the visual cortex in both normally raised and monocularly deprived rats (one eyelid sutured at the age of 11 days) using quantitative receptor autoradiography. Postnatal ontogeny of M1-muscarinic receptors is similar in each visual cortical layer reaching the highest receptor density at the age of 15 days, whereas M2-muscarinic binding sites increase gradually from day 7 up to day 34. Highest 3H-nicotine binding is reached in all visual cortical layers at postnatal day 15 followed by a considerable decrease in binding sites until day 25. Phorbol ester binding rises considerably from birth until the age of 15 days reaching nearly the adult value in the upper layers, whereas in layers V and VI a marked decrease in binding levels until adulthood can be observed. The developmental course of 3H-PN200-110 binding sites is similar in all visual cortical layers and exhibits a moderate rise in binding sites between postnatal days 7 and 15. Monocular deprivation results in permanent changes in the developmental profiles of phorbol ester as well as calcium antagonist binding sites, whereas the alterations in muscarinic and nicotinic cholinergic receptors following monocular deprivation are only of transient nature. The data presented suggest that acetylcholine plays a modulatory role during a certain period of early postnatal maturation of the visual cortex by affecting both cholinergic receptors and associated second messenger cascades.

Age Factors↗
PubMed1992

In vitro fertilization in the natural cycle.

In vitro fertilization in the natural or spontaneous reproductive cycle was first described by Edwards and his colleagues in 1980 following the birth of their first natural cycle IVF baby 2 years earlier. Many groups attempted to follow their lead but it was almost ten years later that the next publication of success appeared (Foulot et al, 1989). The concept of IVF in the natural cycle is particularly attractive and so in 1987 our group also started evaluating the technique. Initial success in the patients with tubal lesions was not translated to patients with other infertility indications. Unfortunately the technique as initially developed was relatively inefficient with significant procedural losses at each stage. Over the succeeding four years a number of changes have been introduced and the efficiency considerably improved. Although these changes have improved take-home baby rates, overall pregnancy rates per embryo have not altered and are still lower than spontaneous in vivo pregnancy rates. It is likely that in the future, with current developments in culture techniques and greater understanding of gamete biology, this situation will change significantly.

Female↗
PubMed1992

Post-antibiotic effect of ceftazidime, ciprofloxacin, imipenem, piperacillin and tobramycin for Pseudomonas cepacia.

The post-antibiotic effects (PAE) of ceftazidime, ciprofloxacin, imipenem, piperacillin and tobramycin were studied for ten strains of Pseudomonas cepacia isolated from patients with cystic fibrosis. Antibiotic concentrations used for exposure were either the MIC of each agent for the sensitive isolates or the recommended sensitivity breakpoint concentrations for the resistant isolates. After 2 h of exposure, cultures were rapidly diluted 1000-fold to eliminate the antibiotic. Out of the ten isolates, there were eight sensitive to ceftazidime, six to ciprofloxacin, six to imipenem, nine to piperacillin and five to tobramycin. All antibiotics tested demonstrated PAE for some isolates of P. cepacia, however, each antibiotic failed to produce a PAE for at least one isolate. The mean PAE was 1.35 h for ceftazidime, 2.38 h for ciprofloxacin, 2.39 h for imipenem, 2.16 h for piperacillin and 1.77 h for tobramycin. Imipenem demonstrated PAE of > or = 0.5 h for all sensitive isolates tested; ceftazidime, piperacillin, ciprofloxacin and tobramycin demonstrated PAE of > or = 0.5 h for 6/8, 8/9, 5/6 and 2/5 sensitive isolates, respectively. These data indicate that several antibiotics have significant (> or = 0.5 h) PAE for isolates of P. cepacia.

Burkholderia cepacia↗
PubMed1992

Adult-onset Still's disease in India.

Adult onset Still's disease was provisionally diagnosed in 31 patients from northern India over a period of five years, in 27 of whom the diagnosis was subsequently felt to have been confirmed. This report describes the clinical characteristics of these patients along with the different therapeutic measures used and their response. Adult onset Still's disease should be considered in the differential diagnosis of 'pyrexia of unknown origin'.

Adolescent↗
PubMed1992

Atropine and naloxone sensitive stimulation produced analgesia from pretectal nucleus in rat.

Mild and brief electrical stimulation of sites in the pretectal nucleus (PTN) of rats evoked potent analgesia of long duration, without significant aversions and was unassociated with motor deficit. The present study has analysed effects of opioidergic and cholinergic neurotransmitter antagonists administered intracerebroventricularly (i.c.v.) on this analgesia. Pretreatment either with naloxone or atropine sulphate both in doses of 30 and 50 micrograms each, respectively i.c.v., 10 min prior to subsequent pretectal stimulation, significantly attenuated the increase in tailflick latency. The antagonism of pretectal stimulation produced analgesia (PSPA) by naloxone and atropine, raises the possibility of involvement of both endogenous opioids and cholinergic mechanisms in pretectal analgesia.

Analgesia↗
PubMed1992

Intravenous midazolam for the treatment of refractory status epilepticus.

OBJECTIVE: To determine the usefulness of midazolam as a therapeutic agent for status epilepticus refractory to conventional treatment. DESIGN: Retrospective study. SETTING: ICUs of two university hospitals. PATIENTS: Seven patients with refractory status epilepticus who failed treatment with diazepam, lorazepam, and phenytoin, with or without phenobarbital. All patients received mechanical ventilation before receiving midazolam. INTERVENTIONS: Intravenous midazolam by bolus administration followed by infusion. MEASUREMENTS AND MAIN RESULTS: Midazolam terminated status epilepticus in all patients in less than 100 secs, as determined by clinical observation (three patients) or electroencephalographic monitoring (four patients). One patient developed mild hypotension. CONCLUSIONS: In this small study, midazolam appears to be an effective and safe alternative to high-dose barbiturate coma for the termination of status epilepticus when conventional agents have failed.

Adult↗
PubMed1992

Septic arthritis due to Pasteurella multocida.

We have reported two cases of septic arthritis caused by Pasteurella multocida, the first, septic polyarthritis unrelated to animal contact and the other, septic monarthritis after a cat scratch. Serious infections with this gram-negative bacillus must be treated with intravenous penicillin, ampicillin, or a third-generation cephalosporin; aminoglycosides are not effective. A high index of suspicion is appropriate when there is a history of a recent animal-inflicted wound, though infection may also occur with either nontraumatic animal contact or no recognized animal contact at all.

Adult↗
PubMed1992

The effect of music on ketamine induced emergence phenomena.

The purpose of this investigation was to assess the influence of music on emergence phenomena after ketamine anaesthesia. Fifty ASA 1 patients undergoing minor gynaecological procedures were randomly divided into two equal groups. Patients in the treated group were played music of their choice through headphones from 5 min before induction of anaesthesia to 15 min postoperatively. Although the incidence of emergence phenomena was similar in both groups the effects tended to be more pleasant and acceptable in those to whom music was played. The majority of patients in the study group (80%) expressed their willingness to have a similar anaesthetic in the future compared to 52% in the control group (p less than 0.05).

Adult↗