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Biomedical subjects

S Thomas

Publications and source records attributed to S Thomas.

At least 433 records · Page 24Linked to original sources
PubMed1995

Regulation of tcp genes in classical and El Tor strains of Vibrio cholerae O1.

Expression of genes encoding the toxin-co-regulated pilus (TCP) varies between the two biotypes of Vibrio cholerae O1. Sequence analysis of the tcp locus from the classical and El Tor strains has revealed differences in the intergenic regions between tcpI and tcpP, and tcpH and tcpA, which may be involved in regulation. To investigate this possibility, transcription of tcpA, and the predicted upstream promoters for tcpI and tcpP, has been analysed in the classical and El Tor strains using promoter-cat (chloramphenicol acetyltransferase) fusions. Together with primer extension analyses, these studies indicate that the tcpA and tcpP promoters are toxR-dependent and suggest that TcpP may be involved in activation of both the tcpI and tcpP promoters. We conclude that differences in the level of tcpA expression in a classical and an El Tor strain are likely to be due to the effect of sequence variation on the ability of control factors to act on these regulatory regions.

Bacterial Outer Membrane Proteins↗
PubMed1995

Physiological control of metabolic flux: the requirement for multisite modulation.

Biochemists have long assumed that the flux through a metabolic pathway can be controlled by the activity of a key regulatory enzyme near the beginning of the pathway. We present the accumulating evidence that every step in this assumption is flawed. Instead, effective physiological control of metabolism is shown to involve simultaneous multisite modulation through action on a number of enzymes.

Binding Sites↗
PubMed1995

Post-transfusion hepatitis revisited.

OBJECTIVE: To evaluate the risk of post-transfusion and postoperative non-A non-B hepatitis in Australia immediately before the introduction of screening for hepatitis C. DESIGN: Retrospective testing of blood samples from a prospective study of cardiac surgery patients. Samples were taken from transfusion recipients and non-transfused controls at regular intervals for 12 months after surgery during 1987-1989. For all donor, recipient and control samples, alanine aminotransferase (ALT) levels were measured and tests for antibody to hepatitis B (anti-HBc, anti-HBs) and, when available, to hepatitis C (anti-HCV) were performed. SETTING: Cardiac surgery units. PARTICIPANTS: Participants were included if they lived in the metropolitan area, and had not had a transfusion in the past year. MAIN OUTCOME MEASURES: Post-transfusion hepatitis (two consecutive samples showing raised ALT levels, > 90 IU/L with no other known cause); hepatitis C infection and carriage (antibody to hepatitis C). RESULTS: Post-transfusion hepatitis occurred in 1.1% of 736 recipients of blood not screened for hepatitis C (i.e., two cases per 1000 unscreened units given). No hepatitis occurred in 514 controls. Seven of the eight patients with post-transfusion hepatitis seroconverted to hepatitis C virus infection. Seven of the 26 anti-HCV-positive donations transmitted hepatitis C, six of these were positive by recombinant immunoblot assay (RIBA) (one by second generation testing only) and one was RIBA indeterminate. Nineteen were RIBA non-reactive; one transmitted hepatitis but the recipient did not develop anti-HCV, although hepatitis C RNA was detected in the donation. Serum ALT was raised in four of the six infective donations. CONCLUSIONS: Hepatitis C virus infection accounted for almost all cases of non-A non-B post-transfusion hepatitis. First generation anti-HCV tests detected about 85% of infective donations. Surrogate testing of donations by ALT or anti-HBc offers no additional advantage.

Alanine Transaminase↗
PubMed1995

Chromosomal analysis in young vs. senescent human fibroblasts by fluorescence in situ hybridization: a selection hypothesis.

Almost all previous studies on chromosomal analysis related to in vitro aging of human fibroblasts were done using only metaphase chromosomes. However, this procedure may provide only partial information since the aneuploidy presumably hidden in interphase cells would remain undetected. For this reason, we have analyzed aneuploidy both at interphase and at metaphase. Female (IMR-90) and male (IMR-91) cells were grown from the lowest to the highest population doubling levels and aneuploidy analysis was done by FISH with alpha-satellite DNA probes of 15 autosomes and two sex chromosomes. Our data on total aneuploidy in young cells indicate that significantly higher proportions of cells with aneuploidy can be detected at interphase than at metaphase. This presumably indicates that during active division of young cells, more aneuploid than diploid cells are selected against entry to mitosis. In contrast, interphase senescent cells from both strains show significantly fewer aneuploid nuclei than do young cells at interphase. This probably indicates that during senescence, there is greater selective pressure in the culture against long-term survival of aneuploid cells than against survival of diploid cells. Our study shows that cellular dynamics with respect to aneuploidy involving various chromosomes differs significantly at interphase and at mitosis during in vitro aging of human fibroblasts, and we propose a 'Selection Hypothesis' as an explanation to our findings.

Aneuploidy↗
PubMed1995

Predictive value of hCG level 14 days after embryo transfer.

OBJECTIVE: It has been reported that the quantitative serum hCG level 14 days after embryo transfer (ET) correlated with pregnancy outcome as well as a likelihood of a multiple gestation pregnancy. This prospective study was designed to assess the predictive value of a 14-day post-ET hCG level with pregnancy outcome and multiple gestation pregnancies. METHODS: Patients undergoing in vitro fertilization (IVF) and ET were monitored by serum quantitative hCG levels 14 days after ET. If positive, serial values of hCG were obtained and transvaginal ultrasound was performed 3 weeks after ET and weekly until fetal cardiac activity was seen. Ongoing pregnancies were defined as greater than 20 weeks. RESULTS: One hundred eleven patients had positive serum quantitative hCG levels 14 days post-ET; 89/111, or 80.2%, had ongoing pregnancies. The spontaneous miscarriage rate was, therefore, 19.8% (22/111). If the level was less than 300, the ongoing multiple pregnancy rate was 9% (5/57). If the level was between 300 and 600, the ongoing pregnancy rate was 40% (10/25). If the hCG level was greater than 600, the multiple pregnancy rate was 100% (7/7). CONCLUSIONS: These data support the hypothesis that hCG levels greater than 200 mIU/ml on 14 days post-ET are more likely to have ongoing pregnancies; hCG levels greater than 600 have a high likelihood of a multiple gestation pregnancy.

Chorionic Gonadotropin↗
PubMed1995

Growth pattern of the Indian fetus.

OBJECTIVES: To determine the pattern of intrauterine growth and the gestation at birth of Indian fetuses. METHOD: One hundred twenty consecutive women who had reliable menstrual histories, low-risk pregnancies and who were booked for delivery at the Christian Medical College Hospital, Vellore, before 20 weeks' gestation were recruited to the study. Ultrasound fetal biometry was carried out at 4-weekly intervals from 20 weeks and at weekly intervals after 36 weeks until delivery. RESULTS: Growth patterns of fetal biparietal diameter and femur length were comparable to those reported in Western populations. However there was a lag in growth of abdominal circumference (AC) after 28 weeks in comparison with that reported in Western populations. The median gestation at delivery following spontaneous labor was 39 weeks. No association was observed between rate of growth of AC and gestation at birth. CONCLUSION: Slowing of growth of the fetal AC after 28 weeks and a shorter length of gestation result in the birth of smaller babies in this ethnic group. The implications of these findings are discussed.

Adult↗
PubMed1995

Profiling "flexible" nursing staff: bank nurses in Scotland.

Nurse banks are locally organised "in house" sources of temporary nursing staff. This paper reports on a survey of nurses working on three nurse banks in the National Health Service in Scotland. A total of 203 nurses responded to the survey, which revealed marked differences in the profile of the nurses working on each of the banks, in terms of age, biographical details, career plans and work commitments. Main issues for management revealed by the survey were the need for good communication with temporary staff and high levels of reported dissatisfaction with access to training opportunities. The paper concludes that there is no "standard" model of a nurse bank in the NHS in Scotland and no standard profile of bank nurses.

Adult↗
PubMed1995

In vitro effects of bicarbonate- versus lactate-buffered continuous ambulatory peritoneal dialysis fluids on peritoneal macrophage function.

At present, lactate is the most commonly used buffer in peritoneal dialysis fluids (PDFs). The high lactate concentration in combination with low original pH was demonstrated to suppress phagocytic function. We evaluated the in vitro effects of a newly formulated bicarbonate-buffered PDF containing glycylglycine (BiGG15 and BiGG40; Pierre Fabre Medicament, Castres, France) on peritoneal macrophage (PMO) function, and compared them with those of equiosmolar lactate-buffered PDF (1.5% and 4.25% glucose; pH 5.4 and pH 7.4) and control buffer. Peritoneal macrophages were isolated from the effluents of 10 continuous ambulatory peritoneal dialysis patients and tested for luminol- and lucigenin-enhanced chemiluminescence, superoxide (O2-) generation measured by cytochrome c reduction, killing capacity, and phagocytosis after incubation in the PDF used. Exposure of PMO to lactate-buffered PDF with an original pH of 5.4 resulted in a significant suppression of all PMO functions measured, compared with bicarbonate- and lactate-buffered PDFs with a pH of 7.4. At physiological pH (7.4), chemiluminescence generation of PMO exposed to BiGG15/40 was significantly higher compared with the corresponding equiosmolar lactate-buffered PDF (1,992 +/- 858 x 10(3) cpm/10(4) cells v 856 +/- 398 x 10(3) cpm/10(4) cells; P < 0.004). O2- generation, killing capacity, and phagocytosis were not significantly different after PMO exposure to bicarbonate compared with exposure to lactate-buffered PDF with a neutral pH. Irrespective of the buffer used, high-osmolality PDFs suppressed PMO function significantly more than low-osmolar PDFs. In conclusion, bicarbonate-buffered PDFs are less detrimental to PMO function than lactate-containing PDFs; these preliminary in vitro results need to be confirmed in vivo.

Bicarbonates↗
PubMed1995

Planning the prevention of alcohol and other drug-related problems among women.

The aim of this paper is to report on the findings from a survey of key respondents with regard to the prevention of alcohol and other drug problems among women. The findings suggest that key respondents were concerned about the problems related to legal substances, alcohol, nicotine, minor tranquillisers, over-the-counter medication and major psychotropic medication. The problems described by these respondents included both physical and psychological health problems. The implications of these findings for prevention activity are discussed.

Journal Article↗
PubMed1995

Managing temporary nursing staff: nurse banks in Scotland.

Nurse banks are locally organized in-house sources of temporary nursing staff. Reports on a study of policy and practice in the management of nurse banks in the National Health Service in Scotland. The study was based on a census survey of all 55 NHS units in Scotland (100 per cent response rate). Examines management rationales in establishing a nurse bank, explores costs and benefits of managing a bank, and provides recommendations on good practice in maintaining continuity of care.

Costs and Cost Analysis↗