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Biomedical subjects

S Sen

Publications and source records attributed to S Sen.

At least 343 records · Page 19Linked to original sources
PubMed1989

Multiple amylase genes in two strains of Bacillus stearothermophilus.

Plasmid DNA fragments from Bacillus stearothermophilus ATCC29609 (BR135) and chromosomal DNA fragments from B. stearothermophilus ATCC31195 (BR132) were cloned into pBR322 and transformed into Escherichia coli strain HB101. Clones were selected which demonstrate extracellular expression of thermostable amylase. The DNA inserts from both strains showed similar restriction maps. Examination of the parental strains revealed plasmids of approx. 100 kb and 35 kb for BR135 and no discernible plasmids for BR132. Hybridization experiments showed that the amylase gene is contained within a 3.2-kb HindIII fragment on both plasmids, and to be present in multiple copies in the BR135 chromosome. Multiple chromosomal copies of the amylase gene were also observed for BR132. Purification of the alpha-amylase produced by the cloned plasmid amy gene yielded a homogeneous 58-kDa protein with thermostable amylase activity.

Blotting, Southern↗
PubMed1989

Betel cytotoxicity.

An attempt to summarise the phytochemical composition of the betel quid, formation of N-nitrosation products during chewing, results of carcinogenicity and mutagenicity studies and the relationship between betel chewing and submucous fibrosis have been made from presently available literature. The present review provides a better understanding of the capacity of the quid ingredients in inducing preneoplastic changes for evaluation of the risk involved with its chewing.

Animals↗
PubMed1989

Chromosomal alterations and DNA content in rats during ageing.

Chromosome analysis of bone marrow cells from 96 sex-matched Rattus norvegicus of 12 different age groups showed a significant increase in hypodiploid cells with ageing. However, in meiotic preparations from gonadal cells of male rats the frequency of hypodiploid or hyperdiploid cells did not change significantly. In situ DNA estimation of bone marrow nuclei, following Feulgen cytophotometry, also did not show any significant difference with gradual age changes.

Aging↗
PubMed1989

Lactate dehydrogenase isozymes in xenotropic virus producing mice.

Lactate dehydrogenase (LDH; E.C. 1.1.1.27) isozymes were compared in three inbred strains of mice, and two strains of wild mice, as well as the F1 hybrids and other genetic crosses involving two of the inbred strains. The strains examined were NZB/B1NJ, 129/J and C57BL/6J, Mus musculus molossinus and M. musculus castaneus. Genetic crosses were made between the xenotropic virus-producing NZB and the non-virus producing 129/J mice. Tissue specificity of LDH in these strains was studied using homogenates of kidney, liver, spleen and thymus. Polymorphism of the enzyme was studied by agarose gel electrophoresis. Enzyme polymorphism in the tissues of NZB and 129/J has not been previously reported. The liver and spleen tissues of 129/J showed the absence of LDH-1 and LDH-2 isozymes. Thymic homogenates of NZB showed a lack of expression of LDH-1, LDH-2 and LDH-3 isozymes. The F1, F2 and the backcross progeny from genetic crosses involving NZB, and 129/J mice showed an isozyme pattern more similar to the non-virus-producing 129/J strain than the virus-producing NZB. Evidence of genetic regulation at the LDH-B subunit appears to be the reason for the differential expression of the isozymes in NZB and 129/J strains. The other inbred strain of mice, C57BL/6J, also showed a greater similarity to the 129/J strain than NZB. The two strains of wild mice were similar in their expression of LDH-isozymes between each other and to the 129/J strain, with respect to the liver and spleen tissues.

Animals↗
PubMed1989

Poliomyelitis in vaccinated children.

Fifty-two children who had received at least 3 properly spaced doses of oral polio-vaccine and had developed acute poliomyelitis inspite of vaccination were studied clinically and serologically. This group (A) was compared with 28 children with poliomyelitis who had not received any vaccination (Group B). A much higher incidence of provocative injection and a better muscle power on presentation was seen in Group A as compared to Group B. Polio-virus type 2 was the commonest etiological agent in Group A (42.3%) whereas type I virus was most commonly seen in Group B (78.6%). A total 53.8% of cases of Group A had protective antibody titres to at least one poliovirus type in the acute phase sera, compared to only 4% from Group B. Six per cent from Group A had protective antibodies to all three virus types, disease in these cases was caused by non-polio agents. Two cases in Group A were possibly vaccine induced paralysis. Recovery, after 60 days, was much better in Group A as compared to Group B. Mortality in the two groups was comparable.

Child↗
PubMed1989

Efficacy of oral water soluble vitamin K in neonates.

Effect of oral water soluble synthetic Vitamin K on prothrombin time was evaluated in 120 full term exclusively breast fed babies. Group A (n = 30) received 1 mg vitamin K (menadione sodium disulphite) intramuscularly at birth, Group B (n = 30) received 0.5 mg intramuscularly, Group C (n = 30) 1 mg orally and Group D (n = 30) did not receive any vitamin K. Prothrombin time (PT) was measured in all between 36-72 hours of age. The PT values in the four Groups A, B, C and D were 17.1 +/- 2.68 seconds, 17.2 +/- 4.42 seconds, 17.0 +/- 2.86 seconds, and 33.1 +/- 12.2 seconds, respectively; the control being 17.0 seconds. The differences between Groups A, B and C were insignificant. Group D babies had a significant prolongation of prothrombin time (p less than 0.001) as compared to the other groups. It is concluded that oral water soluble vitamin K at birth is as good as injectable vitamin K. It is a much simpler form of prophylaxis and avoids intramuscular injection.

Administration, Oral↗
PubMed1989

Problems in the design of anticancer agents.

Theoretically, two predominant paths for obtaining more selective anticancer agents may be envisaged. These are: (a) to make compounds which distribute only or preferentially in cancer cells; (b) to make compounds that are able selectively to kill or to differentiate cancer cells. Although in the last two decades research into new anticancer drugs has not produced satisfactory results, there is solid ground on which novel strategies can be developed, mainly based on a much greater biological knowledge of human tumours. This article does not review all the possible approaches that may be followed, but simply discusses some ideas and problems mainly taken from the current research of our laboratory.

Animals↗
PubMed1988

Cardiac arrhythmias in subarachnoid haemorrhage.

In this prospective study 52 patients with spontaneous subarachnoid haemorrhage were examined with respect to cardiac arrhythmias and their relationship to cerebral lesions. A continuous ECG was registered over an average of five days. Sinus tachycardia was the most frequently recorded arrhythmia, followed by multifocal ventricular extrasystoles, couplets, frequent supraventricular extrasystoles, non-sustained ventricular tachycardia, asystolia and sinus arrhythmia. A significant correlation was found between the clinical manifestation of a midbrain syndrome and sinus arrhythmia, and multifocal ventricular extrasystoles. This correlation points to the autonomic cardiovascular centres as the structures involved.

Adult↗
PubMed1988

Antianginal efficacy of gallopamil in comparison to nifedipine.

In a randomized double-blind crossover trial 30 patients with chronic stable angina were studied to compare the antianginal actions of gallopamil (150 mg/day) and nifedipine. With the initial nifedipine dose of 60 mg/day, the trial had to be stopped because of severe exacerbation of angina in 3 patients of the nifedipine group. Twenty-one patients were entered into a second protocol with the nifedipine dose reduced to 30 mg/day. Compared to the preceding placebo period, the exercise time to onset of angina (+ 30%, P less than 0.01) and the total exercise time (+ 18%, P less than 0.01) were prolonged by gallopamil but not by nifedipine (+ 20 and 13%, respectively, not significant) with no significant difference between the test drugs. Four patients became free of angina during exercise testing with gallopamil therapy and one patient with nifedipine. Both agents significantly reduced ST depression at maximal comparable workload by 77% (gallopamil) and 52% (nifedipine) compared with placebo; the difference between the drugs reached borderline significance (P = 0.055). The increase in heart rate and the rate-pressure product at maximal comparable workload was less with gallopamil than with nifedipine (P less than 0.01). In contrast to nifedipine, very few side effects were reported with gallopamil. Thus, gallopamil is an effective antianginal agent whose therapeutic to toxic ratio appears to be superior to that of nifedipine.

Adult↗
PubMed1988

Spontaneous perforation of the common bile-duct in the neonate: imaging and treatment.

The presence of bile in the peritoneal cavity and obstructive jaundice without liver derangement in the neonatal period is pathognomonic of spontaneous perforation of the bile-ducts. These features can be demonstrated preoperatively with ultrasound, nuclide imaging and liver function tests, without recourse to paracentesis, and the risk of contaminating the bile ascites. Furthermore, the presence of isotope in the general peritoneal cavity will exclude the diagnosis of a choledochal cyst so that jejunum should not be anastamosed to the 'false capsule' of a spontaneous perforation.

Common Bile Duct Diseases↗
PubMed1988

Late onset bowel stenoses after neonatal necrotizing enterocolitis.

In 14 cases of bowel stenoses occurring after neonatal necrotizing enterocolitis (NEC), eight cases presented early, within 8 weeks from the onset of NEC and three beyond 4 months. In the other three cases the stenoses occurred in defunctionalized loops. The late onset stenoses remained undiagnosed until they presented with acute, life-threatening complications, and one of these patients died. We draw attention to these late onset stenoses which could be missed in early contrast studies, and recommend a study at 4 months rather than at 4 weeks, as previously recommended. Those presenting early should not be missed, as all of our cases presented with acute and obvious intestinal obstructions, and they were all still in hospital or undergoing frequent review.

Barium Sulfate↗
PubMed1988

Dorsal enteric cysts--a study of eight cases.

Dorsal enteric cysts have been recognized in association with a wide variety of developmental anomalies of the back, the spine, the central nervous system, the mediastinum and the gut. These lesions can be lethal and they caused the deaths of three of the eight patients in this study: two from meningitis and one from erosion into the aorta. Two of these deaths might have been prevented if they had been fully investigated earlier and the life-threatening components of these complex lesions removed. In the most recent case, however, the lesion was detected antenatally, expediting postnatal investigation and surgery. Three of the five survivors have neurological sequelae attributable to their intraspinal pathology.

Child↗