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Biomedical subjects

H Singh

Publications and source records attributed to H Singh.

At least 19 recordsLinked to original sources
PubMed1992

Very long-chain fatty acids in peroxisomal disease.

Fatty acids with from 24 to 28 carbon atoms (very long-chain fatty acids, VLCFA) are present in small amounts in all mammalian tissues. Even longer chain fatty acids with from 30 to 38 carbon atoms (ultra-long-chain fatty acids, ULCFA) are found in certain specialized tissues including retina, brain, and spermatozoa. In patients with inherited defects in peroxisomal structure and/or function, there is an accumulation of VLCFA in most tissues, while VLCFA and ULCFA levels are increased in brain. The most pronounced changes occur in those patients who have defects in peroxisomal assembly (Zellweger syndrome, infantile Refsum's disease, and neonatal adrenoleukodystrophy). In the brain of these individuals, ULCFA are distributed largely in molecular species of phosphatidylcholine with penta-, hexa-, and heptaenoic acids. In contrast, patients with X-linked adrenoleukodystrophy have increased levels of phosphatidylcholine with monoenoic rather than polyenoic ULCFA. A defect in a peroxisomal VLCFA CoA synthetase or ligase has been reported for these patients, but assembly of their peroxisomes is apparently normal. We speculate that ULCFA are normal products of carbon chain elongation. We have confirmed this by demonstrating the elongation of [1-14C]hexacosatetraenoic acid (26:4n-6) by rat brain in vivo to a series of longer chain tetraenoic acids with carbon chain lengths up to 34. Elongation to ULCFA can occur as well in non-neural tissues as shown by detection of labeled saturated and monoenoic fatty acids with up to 32 carbon atoms after incubation of normal and Zellweger syndrome fibroblasts with [2-14C] acetate. Increased labeling of VLCFA and ULCFA is observed in cells from patients with peroxisomal disorders. Our data suggest that ULCFA with up to at least 32 carbon atoms are formed normally, as a part of the elongation process in most mammalian tissues, and that control of carbon chain elongation is a major function of peroxisomes. Impairment of this function as occurs in peroxisomal disease results in the accumulation of VLCFA and ULCFA. The relative enrichment in normal tissues of ULCFA such as 32:6n-3 in ram and bull spermatozoa and 36:4n-6 in human and rat brain suggests a probable physiological role for this class of fatty acids in these tissues.

Adolescent↗
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

Hepatotoxicity of high dose salicylate therapy in acute rheumatic fever.

Liver function tests, including serum alanine aminotransferase (ALT) activity, serum bilirubin, alkaline phosphatase, serum proteins, blood ammonia levels and intravenous glucose utilization, were monitored in 50 children with acute rheumatic fever receiving anti-rheumatic doses of aspirin. There was a significant increase in blood ammonia levels and serum ALT after aspirin therapy. A significant fall in glucose utilization coefficient was also recorded. Serum alkaline phosphatase, bilirubin and total proteins did not change significantly. Twenty-two of the 50 children recorded a rise in serum ALT; in 12, the rise was five- to tenfold. These 12 children developed adverse symptoms to aspirin. Also, all had a marked rise in blood ammonia levels. The children improved clinically and biochemically on withdrawal of aspirin. There was no constant relationship between hepatocellular function and serum salicylate levels.

Acute Disease↗
PubMed1992

Management of accidental kerosene ingestion.

Accidental kerosene ingestion is still a common problem in Libya. It causes considerable morbidity and occasionally mortality. The role and choice of antibacterial agents in its management remain unsettled. Pulmonary damage has been reported as resulting from aspiration. In aspiration pneumonia, anaerobic organisms may be important pathogens and metronidazole may have a place in therapy. The present randomized trial in 100 children with accidental kerosene ingestion assesses the role of ampicillin, carbenicillin and metronidazole in its management. The results are not conclusive but chemoprophylaxis appears to decrease morbidity. Of the various regimens used, the ampicillin/metronidazole combination was found to be slightly better than the others. Further study is recommended.

Accidents↗
PubMed1992

Ventilatory effects of laparoscopy under general anaesthesia.

We have studied 14 female patients undergoing elective laparoscopy under general anaesthesia with peritoneal insufflation of carbon dioxide in order to examine changes in physiological deadspace (VDphys), arterial to end-tidal carbon dioxide partial pressure difference (PaCO2-PE' CO2) and PaCO2. VCO2 increased after insufflation of carbon dioxide with a mean (SD) maximum increase of 32 (28)% compared with the preinsufflation value. PaCO2 increased also, with a mean (SD) maximum increase of 0.6 (0.58) kPa immediately before carbon dioxide deflation. VDphys and (PaCO2-PE' CO2) increased during laparoscopy, but this was not significant (P greater than 0.05).

Adult↗
PubMed1992

Choice of toothbrush: a survey of dentists' personal preferences and recommendations for patients.

Data on dentists' choice of toothbrush brand/type for personal use and their recommendations for patients were obtained by means of a questionnaire. Seventy-nine per cent of dentists surveyed received free samples, with Oral-B comprising 33 per cent of all such samples, followed by Colgate (16 per cent) and Tek (13 per cent). Fifty-three per cent of dentists surveyed indicated they used all free samples received. Sixty-two per cent of dentists do not consider that different brushes differ significantly in their plaque-removing ability. Therefore, while an effective toothbrushing technique is important, selection of the 'correct toothbrush' from the wide range available may not be critical. The results of the present investigation provide information that is relevant to dental health education and can be applied at the chairside as well as at the broader community level.

Adolescent↗
PubMed1992

BLyF, a novel cell-type- and stage-specific regulator of the B-lymphocyte gene mb-1.

The mb-1 gene encodes an integral membrane protein that appears to be required for the surface expression and signalling function(s) of the immunoglobulin receptor on B lymphocytes. The gene is expressed in a lineage-restricted manner. It is activated early in B-cell ontogeny, continues to be expressed in mature B cells, but is turned off in terminally differentiated plasma cells. We have identified the mb-1 promoter and functionally tested its activity by transient transfections. A 737-bp promoter fragment preferentially stimulates accurately initiated transcription in mb-1-expressing B cells. Deletion analysis of the promoter suggests the presence of two functional domains, proximal and distal. Both domains independently activate transcription from a heterologous promoter. The distal domain functions in a cell-type- and stage-specific manner, activating transcription in B cells but not in T cells or plasma cells. A 25-bp element within this domain is necessary and sufficient for activity. This element is recognized by a novel cell-type- and stage-specific transcription factor termed BLyF. The binding of BLyF completely correlates with the ability of the regulatory element to stimulate transcription. Thus, BLyF appears to positively regulate transcription of the mb-1 gene. Our results also suggest that the inactivity of the mb-1 locus in plasma cells is not simply due to the loss of BLyF activity.

Animals↗
PubMed1992

Timing of acute clinical response to fluphenazine.

The time course of clinical improvement was studied in 41 schizophrenic and schizoaffective acute in-patients treated for 28 days with 10, 20 or 30 mg/day of oral fluphenazine hydrochloride in a double-blind, randomised study. Significant improvement was seen in the four BPRS factors: thinking disturbance, hostile-suspiciousness, withdrawal-retardation and anxious depression. The first two of these factors were improved by day 5. Significant improvement was seen up to day 22 for three of the four factors, but without significant improvement during the last week (although scores continued to drop). The half of the sample showing greater overall improvement did not improve faster than the sample as a whole. These more improved subjects did not differ significantly from the less improved subjects in the thinking disturbance factor until day 15, suggesting that at least a two-week neuroleptic trial would be necessary to begin to differentiate more and less responsive patients. The longer-term course of improvement cannot be determined from these data. The withdrawal-retardation and anxious depression factors showed their greatest improvement later than the 'positive' symptom factors, suggesting that the former may improve as a result of change in the latter.

Acute Disease↗
PubMed1992

Sleep pattern and night awakening in healthy infants.

Sleep pattern and night-awakening were studied in 500 healthy infants by a semistructured interview method. A total of 92.2% infants shared bed with their mothers, 6.8% with grand parents and 1% with fathers. Paternal participation at bedtime was observed to be insignificant. Infants of non-working mothers and families with vegetarian habits slept significantly more as compared to the working mothers and families with non-vegetarian habits. Night-time awakening was reported in 96% of the infants. If a child is functioning well in other areas of life, parents can be assured that the problem is not of serious concern and unnecessary medication of infants should be avoided.

Age Factors↗
PubMed1992

Peroxisomal beta-oxidation of branched chain fatty acids in human skin fibroblasts.

Human skin fibroblasts in suspension are able to degrade [1-14C]-labeled alpha- and gamma-methyl branched chain fatty acids such as pristanic and homophytanic acid. Pristanic acid was converted to propionyl-CoA, whereas homophytanic acid was beta-oxidized to acetyl-CoA. Incubation of skin fibroblasts with [1-14C]-labeled fatty acids for longer periods produced radiolabeled carbon dioxide, presumably by further degradation of acetyl-CoA or propionyl-CoA generated by beta-oxidation. Under the same conditions similar products were produced from very long chain fatty acids, such as lignoceric acid. Inclusion of digitonin (> 10 micrograms/ml) in the incubations strongly inhibited carbon dioxide production but stimulated acetyl-CoA or propionyl-CoA production from fatty acids. ATP, Mg2+, coenzyme A, NAD+ and L-carnitine stimulated acetyl-CoA or propionyl-CoA production from [1-14C]-labeled fatty acids in skin fibroblast suspensions. Branched chain fatty acid beta-oxidation was reduced in peroxisome-deficient cells (Zellweger syndrome and infantile Refsum's disease) but they were beta-oxidized normally in cells from patients with X-linked adrenoleukodystrophy (ALD). Under the same conditions, lignoceric acid beta-oxidation was impaired in the above three peroxisomal disease states. These results provide evidence that branched chain fatty acid, as well as very long chain fatty acid, beta-oxidation occurs only in peroxisomes. As the defect in X-linked ALD is in a peroxisomal fatty acyl-CoA synthetase, which is believed to be specific for very long chain fatty acids, we postulate that different synthetases are involved in the activation of branched chain and very long chain fatty acids in peroxisomes.

Antimycin A↗
PubMed1992

Stool electrolytes in acute dehydrating gastroenteritis.

Stool electrolytes were studied in 100 cases of gastroenteritis. The duration of illness was 24-48 hours in 32% and 72-96 hours in 28% of the cases. On stool culture, 43% children had no growth, 23% had Enteropathogenic E. coli and 10% had cholera and rotavirus each. The stool sodium loss was more in cholera and shigella cases, diarrhea of shorter duration and in children between 24-30 months of age. Potassium loss in the stool was more in shiegella cases, diarrhea of short duration and in children between 30-36 months of age. In cases of gastroenteritis with severe malnutrition, stool sodium loss was less; stool potassium loss was not affected by the nutritional status. Total electrolytes lost in stools can be estimated by knowing purging rate and rehydration therapy can be planned accordingly.

Acute Disease↗
PubMed1991

Pattern of substance abuse among secondary school students in Trinidad and Tobago.

A questionnaire survey of 1,603 secondary school students, aged 14-18 years, was conducted in Trinidad and Tobago in 1988. Prevalence of alcohol use was 84%, tobacco 35%, marijuana 8% and cocaine 2%. Alcohol was the substance most consistently used and students' first exposure to drinking alcohol was with family members. Transitions from primary to secondary schools and from junior to senior schools were associated with increased reporting of alcohol use. Significantly more Indo-Trinidadian than Afro-Trinidadian students reported using alcohol frequently. Conversely more Afro-Trinidadian students than Indo-Trinidadians reported using marijuana. The use of alcohol by students was positively correlated to its use by fathers and negatively with religious activities. The use of drugs among students appears to be a growing problem. There is a need for the implementation of culturally relevant educational prevention programmes in schools.

Adolescent↗