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Biomedical subjects

J George

Publications and source records attributed to J George.

At least 307 records · Page 17Linked to original sources
PubMed1983

Hydrocephalus caused by tuberculous meningitis: clinical picture, CT findings and results of shunt surgery.

This study is an analysis of 70 children, five months to eleven years of age, with hydrocephalus secondary to tuberculous meningitis. They presented as an acute illness, mostly in early childhood, with disturbance of consciousness, convulsions, rigidity and, sometimes, neurological deficit. CT scans showed ventricular dilatation, periventricular translucency and exudates in basal cisterns. Shunt surgery performed early produced gratifying results without dissemination of tuberculosis. Residual ventricular dilatation following shunt surgery was inversely related to intellectual status. Even with advanced degrees of tuberculous meningitis, thirteen of the twenty-eight children tested for intellectual status were found to be educable or having near normal intelligence. Fatal intraventricular haemorrhages were seen in six cases as a late complication.

Cerebral Ventriculography↗
PubMed1983

Oncogenic transformation of mouse BALB/3T3 cells by plutonium-238 alpha particles.

The A31-11 mouse BALB/3T3 cell system was adapted for the study of malignant transformation induced by 5.3 MeV alpha particles from a specially constructed 238Pu source. The biologic effects were compared to those of 220 kVp X rays. The alpha-radiation survival curve showed a D0 of 70 rad and a relative biological effectiveness (RBE) of 3.5 at 50% survival. The transformation frequency increased exponentially with dose in the range examined (25-250 rad); the maximum RBE for the induction of transformation in growing cells was approximately 3. The RBE for alpha transformation in nonproliferating cells, however, appeared to be much higher; the yield of transformants among X-irradiated cells held in the stationary phase of growth for 6 to 220 hr after irradiation declined nearly 50-fold while no decrease occurred in alpha-irradiated cells. This finding supports the hypothesis that carcinogenic damage induced by high LET radiation in mammalian cells is inefficiently repaired compared with X-ray damage, and that the carcinogenic effect of exposures to high LET radiation may be simply cumulative in nature. It further suggests that the effective RBE for alpha radiation in nonproliferating cell populations in vivo may be much higher than one would predict based on measurements in dividing cells.

Alpha Particles↗
PubMed1982

Sequence-specific endonuclease BamHI: relaxation of sequence recognition.

The effect of glycerol on the specificity of DNA cleavage by the restriction endonuclease BamHI has been examined. In addition to the canonical G decreases from G-A-T-C-C site, BamHI cuts DNA at several sites that we have named noncanonical BamHI.1 sites. The number of BamHI.1 sites in simian virus 40 and pBR322 was determined to be 13 for each DNA. Cutting sites determined by DNA sequence analysis include G decreases from G-A-A-C-C, G decreases from G-C-T-C-C, G decreases from G-G-T-C-C, and G-A-A-T-C-C with the complementary strand sequence assignments of G-G-T-T-C-C, G-G-A-G-C-C, G-G-A-C-C-C, and G-G-A-T-T-C. The relaxation in specificity was related to hydrogen bond acceptor and donor sites in the recognition sequence, in an attempt to generate a model of BamHI recognition of cognate sites in DNA.

Bacillus↗
PubMed1982

Discriminating good sleepers from insomniacs using all-night polysomnograms conducted at home.

Twelve good sleepers and 12 insomniacs were recorded over three nights in their homes. Subjective assessment of sleep indicated minimal disruption due to sleep recording procedures. A cut point of 88 per cent sleep efficiency resulted in correct classification of nine poor sleepers and 10 good sleepers. Multiple discriminant function analyses, using variables related to rapid eye movement sleep, resulted in the same number of correct classifications. The two indices combined resulted in 100 per cent exclusion of false positives for good sleepers and insomniacs. Insomniacs also showed more night-to night variability in sleep and greater difficulty in returning to sleep once aroused. These results show that good sleepers and insomniacs can be distinquished with a high degree of resolution using variables derived from the home all-night sleep recording.

Adult↗
PubMed1981

Double blind controlled trial of deanol in tardive dyskinesia.

Thirty three chronic psychiatric hospital subjects with oral tardive dyskinesia were divided into three groups. The subjects were matched for severity of symptoms then randomly assigned to treatment with a placebo, 1 g deanol or 2 g deanol per day. Statistical analysis showed that after 30 days treatment, there was a significant reduction in the mean rating of the movements of the group of 11 subjects on 2 g deanol per day. Six of these subjects showed substantial reduction in movement. Further studies using this dosage of deanol are unwarranted.

Aged↗
PubMed1980

Sequence-specific endonuclease Bam HI. Effect of hydrophobic reagents on sequence recognition and catalysis.

The specificity of cleavage of Bam HI is altered in the presence of hydrophobic reagents, such as glycerol and M2SO. The enzyme with altered specificity, designated Bam HI.1, generated digestion patterns of various DNAs, which were distinct from those generated by Bam HI. Cleavage sites recognized in phiX174 RF DNA in the presence of these hydrophobic reagents are not related to the Bam HI palindrome. Bam HI.1 appears to be an endogenous form of Bam HI that can be expressed by altering the hydrophobicity of the reaction.

Bacteriophage phi X 174↗
PubMed1980

Suppression of induction of SOS functions in an Escherichia coli tif-1 mutant by plasmid R100.1.

The tif-1 mutation in the recA gene of Escherichia coli caused, at 40 degrees C, lethal cell filamentation, induction of the recA protein, mutagenesis, and, in lambda lysogens, prophage induction. The presence of plasmid R100.1 in tif-1 strains suppressed tif-mediated cell filamentation and killing, recA protein induction, and prophage induction in lysogens. It also reduced mutagenesis in a tif-1 sfiA11(R100.1) strain. Plasmids F'lac, P1, and pMB9, in contrast, had little or no effect on tif-mediated induction of lambda. The presence of R100.1 did not inhibit the induction of the recA protein or of lambda by ultraviolet irradiation or mitomycin C treatment of tif-1(R100.1) or tif-1(lambda)(R100.1) strains.

Adenine↗