Biomedical subjects
B Thomas
Publications and source records attributed to B Thomas.
Evidence that recBC-dependent degradation of duplex DNA in Escherichia coli recD mutants involves DNA unwinding.
Infection of Escherichia coli with phage T4 gene 2am was used to transport 3H-labeled linear duplex DNA into cells to follow its degradation in relation to the cellular genotype. In wild-type cells, 49% of the DNA was made acid soluble within 60 min; in recB or recC cells, only about 5% of the DNA was made acid soluble. Remarkably, in recD cells about 25% of the DNA was rendered acid soluble. The DNA degradation in recD cells depended on intact recB and recC genes. The degradation in recD cells was largely decreased by mutations in recJ (which eliminates the 5' single-strand-specific exonuclease coded by this gene) or xonA (which abolishes the 3' single-strand-specific exonuclease I). In a recD recJ xonA triple mutant, the degradation of linear duplex DNA was roughly at the level of a recB mutant. Results similar to those with the set of recD strains were also obtained with a recC++ mutant (in which the RecD protein is intact but does not function) and its recJ, xonA, and recJ xonA derivatives. The observations provide evidence for a recBC-dependent DNA-unwinding activity that renders unwound DNA susceptible to exonucleolytic degradation. It is proposed that the DNA-unwinding activity causes the efficient recombination, DNA repair, and SOS induction (after application of nalidixic acid) in recD mutants. The RecBC helicase indirectly detected here may have a central function in Chi-dependent recombination and in the recombinational repair of double-strand breaks by the RecBCD pathway.
Accreditation of university nursing programmes in Canada.
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Organizing your school for accreditation.
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Accuracy and completeness of Scottish mental hospital in-patient data.
In Scotland the Information and Statistics Division of the Scottish Office Home and Health Department maintains a computerised record of patients who have been admitted to, discharged from or have died in Scottish mental hospitals. This data source is of particular value to those involved in planning health care provision and to epidemiologists. The present study assesses the quality of these data in relation to patients with verified presenile dementia who have been discharged from the Royal Edinburgh Hospital between 1974 and 1988. Seventeen per cent of presenile patients were not identified and 23% of patients were wrongly classified. More than 93% of patients with presenile Alzheimer's disease were identified, though often under a variety of other diagnostic codes. These findings highlight limitations of the data supplied and suggest that the usefulness of this enviable and unique data source could be enhanced if the medical profession took greater care in clearly stating an International Classification of Diseases diagnosis in a patient's hospital record.
Detection of Chlamydia trachomatis by direct immunofluorescence improved by centrifugation of specimens.
During a study of women with laparoscopically investigated pelvic pain, genital tract specimens were examined for Chlamydia trachomatis using a direct fluorescent antibody (DFA) technique (MicroTrak, Syva) and culture. Some smears, particularly those from the upper genital tract, contained an inadequate number of cells when examined by the DFA technique and many cell monolayers were destroyed by the specimens. To obtain results for such samples, or to confirm the original DFA result, additional specimens which had been frozen at -70 degrees C or in liquid nitrogen were centrifuged at high speed and the resulting deposit examined by the DFA technique. By this means, 32 negative results were confirmed for specimens from 10 chlamydia-negative patients with pelvic inflammatory disease or with high chlamydial antibody titres, and 26 negative results were confirmed for 19 patients who were positive at other sites. In addition, three chlamydia-positive and six chlamydia-negative results were obtained for sites where the original smear for DFA testing had been inadequate (few epithelial cells) and six specimens that were negative originally were found to be positive. Thus, of 73 specimens that were either inadequate or negative by DFA testing originally, 9 (12%) were positive by DFA testing after centrifugation.
Steroid hormones in lymph and blood from women with early breast cancer.
Postoperative levels of steroid hormones have been measured in lymph and blood of 28 patients undergoing iridium implants as part of conservative treatment for operable breast cancer. The aim was to establish whether there were higher levels of hormones in lymph draining from necrosing tumour cells compared with peripheral blood levels. No differences were found in the ratios of estradiol, dehydroxyepiandrosterone sulphate or sex hormone-binding globulin in those patients with complete compared with incomplete excision of the primary tumour. However, premenopausal patients who had an incompletely excised primary tumour had increased levels of free testosterone in lymph draining from the tumour site on the third and fourth postoperative days. Thus androgens may have an important role in the intracellular metabolism of some breast cancers.
Ultrastructural localization of the allergen Der p I in the gut of the house dust mite Dermatophagoides pteronyssinus.
The sites and concentrations of Der p I within the house dust mite were determined. Highest concentrations were found in the epithelium of the posterior end of the mite stomach, implying that this is the site of Der p I synthesis and secretion.
Chlamydia trachomatis in the fallopian tubes of women without laparoscopic evidence of salpingitis.
23 women with lower abdominal pain and Chlamydia trachomatis in the cervix, urethra, or both sites were studied. Laparoscopy was done with sampling of the endometrium and fallopian tubes for detection of C trachomatis. 11 women had laparoscopic evidence of pelvic inflammatory disease (PID); C trachomatis was detected in the upper genital tract of 8, but not in the upper tract of 5 who had laparoscopy again after treatment. The organism was also found in the upper genital tract of 9 of the 12 women without laparoscopic evidence of PID. Most of the women with abdominal pain or tenderness had tubal or endometrial C trachomatis infection, although only half had laparoscopic evidence of salpingitis. This finding suggests that antibiotic treatment should be given as soon as chlamydial infection is detected in the cervix and that pain does not necessarily point to C trachomatis in the upper genital tract. Laparoscopy may miss important pathogens in the upper genital tract, unless the procedure is complemented with detailed microbiological investigation.
Comparison of ofloxacin with doxycycline in the treatment of non-gonococcal urethritis and cervical chlamydial infection.
The efficacy of ofloxacin was compared with that of doxycycline in the treatment of non-gonococcal urethritis (NGU) and cervical chlamydial infection in an open randomized study. In total, 182 men and 100 women were enrolled: 92 men and 50 women received ofloxacin at a dose of 400 mg once daily for seven days, and 90 men and 50 women received doxycycline at a dose of 100 mg twice daily for seven days. All women and 42 men, that is 29 men in the ofloxacin group (32%) and 13 in the doxycycline group (14%) were chlamydia-positive on entry into the study. Patients were reviewed on completion of the treatment course (day 8) and two weeks later (day 22). Clinical cure rates for NGU in assessable patients in each treatment group were similar; 73% in the ofloxacin group and 63% in the doxycycline group at day 8, and 70% and 90% in the respective treatment groups on study completion. Repeat tests for chlamydiae were negative for all male and female patients at both day 8 and day 22. Both ofloxacin and doxycycline were well tolerated. We conclude that ofloxacin given at a dose of 400 mg once daily for seven days is a safe and effective alternative treatment for NGU and cervical chlamydial infection.
Characterization of conformers of D 1 of photosystem II using site-directed antibodies.
Antibodies have been raised to synthetic peptides, corresponding to a region in the loop spanning helices 4 and 5 of D 1 protein (Ala 250-Phe 265) and to a region anticipated to be near the C terminus of mature D 1 (His 332-Ala 345). Polyclonal antibodies to the sequence His 332-Ala 345 reacted with a 32 kDa polypeptide in thylakoid preparations identified as D 1 from its resistance (pea) or susceptibility (wheat) to lysine-C degradation. A monoclonal antibody to His 332-Ala 345 reacted preferentially with a faster migrating polypeptide in SDS electrophoresis, a putative conformer of D 1. Polyclonal antibodies to the sequence Ala 250-Phe 265 also reacted with the faster running polypeptide but not with the population of molecules running at 32 kDa. The putative conformer of D 1 from wheat appears to be more resistant than the main D 1 population to lysine-C degradation. Peptide analyses by Takahashi et al. [(1988) FEBS Lett, 240, 6-8] suggest Asn 335-Ala 344 lies at the processed C terminus. The present report provides immunological confirmation that this sequence is retained in mature D 1.
Happy families. Phytochrome properties and biological action: A NATO Advanced Research Workshop, Chichester, UK, July 22-27, 1990.
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Anticonvulsant treatment of psychoses.
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On evolutionarily stable strategies in populations with subpopulations having isolated strategy repertoires.
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Developing a challenge system.
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Project tomorrow is now.
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Chlorhexidine resistance and the lipids of Providencia stuartii.
The lipid composition of Providencia stuartii has been shown to resemble closely that of Proteus mirabilis. The ability of some Pv, stuartii strains to survive exposure to high concentrations of the antiseptic chlorhexidine could not be explained in terms of differences in lipid content between sensitive and resistant strains. In addition, resistance could not be attributed to either reduced adsorption of the antiseptic or to its gross enzymic degradation.