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Biomedical subjects

B J Thomas

Publications and source records attributed to B J Thomas.

At least 73 records · Page 4Linked to original sources
PubMed1997

Massive osteolysis after ceramic on ceramic total hip arthroplasty. A case report.

The case of a 66-year-old woman who sustained a pathologic femur fracture secondary to extensive osteolysis distal to a pressfit femoral prosthesis with a ceramic on ceramic bearing surface is reported. The femoral and acetabular bearing surfaces showed signs of visible wear, although the stem showed little evidence of burnishing. Material curetted from the femoral medullary canal in the area of the osteolysis contained extensive amounts of histiocytes and foreign body debris. Qualitative spectrographic analysis of the curetted material showed levels of aluminum to be approximately 10 times more prevalent than either cobalt or chromium. Although there is little understanding of the cellular reactions to ceramic debris products, the extensive osteolysis seen in this patient suggests that alumina ceramic bearings may not be as biologically inert as initially perceived.

Aged↗
PubMed1997

An association between non-gonococcal urethritis and bacterial vaginosis and the implications for patients and their sexual partners.

OBJECTIVES: The aetiology of non-gonococcal urethritis (NGU) in a considerable proportion of men remains unaccounted for. We wished to investigate the possible aetiological role of bacterial vaginosis (BV), the commonest cause of abnormal discharge in women, in this condition. METHODS: We carried out two studies. In the first, case-control, study, we recruited men with and without NGU and examined their female partners for evidence of BV. The second, cohort design, study which ran concurrently with the first study involved recruiting women with and without BV and examining their male partners for evidence of NGU. The diagnoses of both NGU and BV were made microscopically to include symptomatic and asymptomatic individuals in both disease categories. RESULTS: In the case-control study 51 couples were recruited. Of these 39 men had NGU and 12 (31%) of their female contacts had BV. In contrast, of 12 men without NGU, only one (8%) of the female partners had BV (odds ratio 4.89, 95% CI: 0.51-42.27). When only Chlamydia trachomatis negative patients were considered, the odds ratio for an association between BV and NGU was increased to 6.77, 95% CI: 0.73-62.68). Thirty eight couples were recruited to the cohort design study. Of 17 women with BV, 12 (71%) of their male partners had NGU. In contrast, of 21 women without BV, seven (33%) of their male partners had NGU (p = 0.049, odds ratio 4.8). When only C trachomatis negative patients were considered, the significance of the association was increased (p = 0.037; odds ratio 5.42). CONCLUSIONS: An association exists between NGU and BV, and vice versa. If BV arises de novo the findings could help to explain the development of urethritis in stable sexual relationships.

Adult↗
PubMed1997

The efficacy of prophylaxis with low-dose warfarin for prevention of pulmonary embolism following total hip arthroplasty.

The selection of a prophylaxis regimen and its implementation have been influenced considerably by the decreased duration of hospital stays and the pressures of cost containment. The purpose of the present study was to determine the rate of symptomatic pulmonary embolism both before and after discharge, the number of days required to achieve an adequate level of anticoagulation, and the complications associated with the use of low-dose warfarin after total hip arthroplasty. Between 1987 and 1993, 1099 primary and revision total hip arthroplasties were performed in 940 patients who received low-dose warfarin for prophylaxis against thromboembolic disease. The average duration of prophylaxis was fifteen days (range, one to twenty-nine days). The target level of anticoagulation (as indicated by a prothrombin time of fourteen to seventeen seconds) was achieved an average of three days (range, one to sixteen days) after the operation. The level of anticoagulation was lower than the target range at the time of discharge after 257 total hip arthroplasties (23.4 per cent), and the target level was never achieved during the period of hospitalization after fifty-four such procedures (4.9 per cent). Twelve total hip arthroplasties were associated with a symptomatic pulmonary embolism; the over-all prevalence of this complication therefore was 1.1 per cent (95 per cent confidence interval, 0.4 to 1.9 per cent). Four pulmonary emboli were diagnosed before discharge and eight, after discharge. A fatal pulmonary embolism occurred after one procedure (0.1 per cent). Patients who had a history of symptomatic venous thromboembolic disease had a significantly increased risk of symptomatic pulmonary embolism after total hip arthroplasty (p = 0.001, Fisher exact test). A major bleeding episode occurred after thirty-two total hip arthroplasties (2.9 per cent). Patients who had a prothrombin time of more than seventeen seconds had a significantly increased risk of hematoma formation (p = 0.003, chi-square analysis). Prophylaxis with low-dose warfarin is safe and effective for the prevention of pulmonary embolism after total hip arthroplasty.

Adult↗
PubMed1996

daughterless is required for Drosophila photoreceptor cell determination, eye morphogenesis, and cell cycle progression.

Initiation of Drosophila peripheral nervous system (PNS) development requires the achaete-scute complex (AS-C) and the atonal (ato) genes. The AS-C and ato encode basic helix-loop-helix (bHLH) transcription factors that dimerize in vitro with another bHLH protein, daughterless (da). da has many functions during Drosophila embryonic development, as it is required for proper sex determination, oogenesis, and neurogenesis. Here, we examine the expression and function of da within the developing Drosophila eye. The use of a monoclonal antibody to the Da protein revealed that Da levels are modulated across the developing eye disc. Within the morphogenetic furrow (MF) and photoreceptor cell R8, there is a cell-by-cell correspondence between high levels of Da protein expression and Ato protein expression. Mosaic analysis of adult tissue demonstrates that da function is cell autonomous and required within R2, R3, R4, R5, and R8. Examination of gene expression in da- imaginal disc clones reveals that da regulates Ato expression in the MF, affects the progression of the MF, and is necessary for the reestablishment of the G2 and M phases of the synchronized cell cycle posterior to the MF.

Animals↗
PubMed1996

Isolation of Drosophila cyclin D, a protein expressed in the morphogenetic furrow before entry into S phase.

During Drosophila development, nuclear and cell divisions are coordinated in response to developmental signals. In yeast and mammalian cells, signals that control cell division regulate the activity of cyclin-dependent kinases (Cdks) through proteins such as cyclins that interact with the Cdks. Here we describe two Drosophila cyclins identified from a set of Cdk-interacting proteins. One, cyclin J, is of a distinctive sequence type; its exclusive maternal expression pattern suggests that it may regulate oogenesis or the early nuclear divisions of embryogenesis. The other belongs to the D class of cyclins, previously identified in mammalian cells. We show that Drosophila cyclin D is expressed in early embryos and in imaginal disc cells in a pattern that anticipates cell divisions. Expression in the developing eye disc at the anterior edge of the morphogenetic furrow suggests that cyclin D acts early, prior to cyclin E, in inducing G1-arrested cells to enter S phase. Our results also suggest that, although cyclin D may be necessary, its expression alone is not sufficient to initiate the events leading to S phase.

Amino Acid Sequence↗
PubMed1996

Bioelectrical impedance for monitoring the efficacy of lymphoedema treatment programmes.

The treatment of lymphoedema includes a combination of massage, compression bandaging, and exercise. To date the most common technique of assessing the efficacy of treatment has involved estimating the total limb volume from circumferential measurements at fixed intervals along the limb. This study investigated the application of multiple frequency bioelectrical impedance analysis, MFBIA, to monitor the volume of lymphoedema in the upper limb of patients who developed this disorder following surgery for cancer of the breast. Daily measurements of both circumference and impedance of both the affected and unaffected limbs were recorded for 20 patients throughout their 4 week treatment programmes. Twenty control subjects were also monitored daily over a similar 4 week period. Prior to the commencement of treatment the bioimpedance technique detected a significant (P < 0.01) asymmetry between the two limbs of the control subjects, associated with handedness (P < 0.001). Circumferential estimates of limb volumes in the control group detected no asymmetry. Impedance measures of extracellular fluid showed all of the patients to lie outside the 95% confidence interval determined from the data of the control group. The trends of the impedance measures and the circumferential estimates of volume throughout the 4 week program were found to be significantly different (P < 0.05); MFBIA exhibiting a greater sensitivity in the detection of lymphoedema. The results demonstrate that MFBIA is significantly more sensitive than circumferential measurement both in the early diagnosis of lymphoedema and in monitoring change.

Adult↗
PubMed1996

Total hip arthroplasty.

Total hip arthroplasty continues to be an extremely successful procedure, with ever-widening indications and regular improvement in technique, materials, and design. In the past year several studies were published evaluating the results of both cemented and cementless total hip arthroplasty at mid- to long-term follow-up. In addition, careful analysis of basic laboratory studies including finite-element analyses have added to our understanding of materials and design. Specific findings in the past year included poor results with cemented hips in younger patients at long-term follow-up of greater than 16 years. A lower incidence of loosening has been found for cobalt chrome-cemented components compared with titanium-cemented components. No difference was found in the results of metal-backed versus non-metal backed cemented acetabular components, and an increasing incidence of loosening was shown for cemented acetabular components with time. The newer cementless hip arthroplasties showed evidence of learning curve, particularly with regard to innovative design such as acetabular screw rings, whereas porous-coated hemispherical cups appeared to do well. Thigh pain continues to be a problem with cementless designs, and the controversy of titanium versus cobalt chrome for cementless femoral stem designs continues at full tilt.

Adult↗
PubMed1996

Detection and widespread distribution of Chlamydia pneumoniae in the vascular system and its possible implications.

AIMS: To attempt to detect Chlamydia pneumoniae DNA in atheromatous vascular tissue. METHODS: A modification of an existing polymerase chain reaction (PCR) assay and immunofluorescence staining with a monoclonal antibody directed against C pneumoniae were used to detect C pneumoniae. Specimens from 32 patients undergoing abdominal aortic aneurysm repair were examined. Vascular tissue, ostensibly normal, from six liver transplant donors was also examined for comparison. Altogether, 43 vessels from these 38 subjects (age range 36-85 years) were examined. RESULTS: C pneumoniae was detected in 11 (44%) of 25 aortas, five (55%) of nine iliac arteries, two (40%) of five femoral arteries, and one of two iliac veins. Immunofluorescence staining supported positive PCR results in three of 12 cases in which it was used. Overall, C pneumoniae was detected in the arteries of 14 (44%) of the patients undergoing vascular surgery and three (50%) of the donors. CONCLUSIONS: This study is the first in the UK in which C pneumoniae organisms have been found in atherosclerotic vessels and the tendency for the organisms to be present most often in such vessels exhibiting chronic inflammatory changes suggests that a search for them in various forms of arteritis may also be rewarding.

Adult↗
PubMed1996

Monitoring of extracellular and total body water during haemodialysis using multifrequency bio-electrical impedance analysis.

Multifrequency bio-electrical impedance analysis (MFBIA) was evaluated as a technique for monitoring changes in extracellular and total body water (ECW and TBW, respectively) of 15 subjects during dialysis. Dilution analysis, using deuterium oxide and sodium bromide, was also performed on each subject before dialysis so that prediction equations for ECW and TBW based on the MFBIA measures could be developed. These prediction equations were then used to estimate water compartment volume changes during dialysis and compared with volumetric measures of the dialysate removed. The results show that MFBIA does not accurately measure ECW and TBW changes during dialysis. The MFBIA measures tend to overestimate the changes and are not sufficiently precise to be clinically useful.

Adult↗
PubMed1996

Differences between patients' and physicians' evaluations of outcome after total hip arthroplasty.

The purpose of this study was to compare patients' and physicians' evaluations of the results of 147 total hip arthroplasties. The patients and physicians independently evaluated pain and over-all satisfaction with the outcome of the procedure using a 10.0-centimeter visual-analog scale. They also answered a questionnaire with which they assessed general health, functional ability, and pain. The mean (and standard deviation) analog rating for pain (with 0.0 centimeters indicating no pain and 10.0 centimeters, severe pain) was 1.7 +/- 2.6 centimeters as assessed by the patients and 1.1 +/- 1.8 centimeters as assessed by the physicians (p < 0.001, paired t test). The mean analog rating for over-all satisfaction (with 0.0 centimeters indicating poor and 10.0 centimeters, excellent) was 8.6 +/- 2.1 centimeters as assessed by the patients and 8.8 +/- 1.7 centimeters as assessed by the physicians (p = 0.07, paired t test). There was a marked disparity between the patients' and the physicians' scores when the patients assigned a low score to a particular area. For the thirty patients who rated the pain as more than 4.0 centimeters, the mean analog rating was 6.8 +/- 2.1 centimeters according to the patients, while it was 3.6 +/- 2.7 centimeters according to the physicians (p < 0.001, linear regression). The mean analog rating for over-all satisfaction according to the nineteen patients who rated this parameter as less than 7.0 centimeters was 3.8 +/- 2.0 centimeters, while the mean rating according to the physicians 6.5 +/- 2.8 centimeters (p < 0.001, linear regression). The patients' and physicians' evaluations were similar regarding the results of the total hip arthroplasty when the patients had little or no pain and were satisfied with the result. However, the disparity increased as the patients' ratings for pain increased and their ratings for over-all satisfaction decreased. This study highlights a discrepancy between patients' and physicians' evaluations of the results of total hip arthroplasty. This discrepancy increased when the patient was not satisfied with the outcome. The use of patients' self-administered questionnaires as well as traditional physician-generated assessments may provide a more complete evaluation of the results of total hip arthroplasty.

Activities of Daily Living↗
PubMed1996

Total hip replacement: the current perspective after 37 years.

The first hip replacements of the modern era were performed by Sir John Charnley in 1959,using poly- tetrafluoroethylene for the acetabulum and polymethylmethacrylate cement to secure the stainless steel femoral component. These initial operations were not a success due to excessive wear of the PTFE bearing surface. The operation was not acknowledged to be the success it is today until 1962when Charnley switched to using high-density polyethylene for the acetabular component and the "low-friction arthroplasty" was introduced.' This prosthesis has remained the "gold standard" until the present day with relatively few changes to the original concept, and with considerable success with published results in excess of 20 years.'

Journal Article↗
PubMed1996

Evaluation of multiple frequency bioelectrical impedance and Cole-Cole analysis for the assessment of body water volumes in healthy humans.

OBJECTIVE: To assess the application of a Cole-Cole analysis of multiple frequency bioelectrical impedance analysis (MFBIA) measurements to predict total body water (TBW) and extracellular water (ECW) in humans. This technique has previously been shown to produce accurate and reliable estimates in both normal and abnormal animals. DESIGN: The whole body impedance of 60 healthy humans was measured at 496 frequencies (ranging from 4 kHz to 1 MHz) and the impedance at zero frequency, Ro, and at the characteristic frequency, Zc, were determined from the impedance spectrum, (Cole-Cole plot). TBW and ECW were independently determined using deuterium and bromide tracer dilution techniques. SETTING: At the Dunn Clinical Nutrition Centre and The Department of Biochemistry, University of Queensland. SUBJECTS: 60 healthy adult volunteers (27 men and 33 women, aged 18-45 years). RESULTS: The results presented suggest that the swept frequency bioimpedance technique estimates total body water, (SEE = 5.2%), and extracellular water, (SEE = 10%), only slightly better in normal, healthy subjects than a method based on single frequency bioimpedance or anthropometric estimates based on weight, height and gender. CONCLUSIONS: This study has undertaken the most extensive analysis to date of relationships between TBW (and ECW) and individual impedances obtained at different frequencies ( > 400 frequencies), and has shown marginal advantages of using one frequency over another, even if values predicted from theoretical bioimpedance models are used in the estimations. However in situations where there are disturbances of fluid distribution, values predicted from the Cole-Cole analysis of swept frequency bioimpedance measurements could prove to be more useful.

Adolescent↗
PubMed1995

Evaluation of a commercial polymerase chain reaction assay for Chlamydia trachomatis and suggestions for improving sensitivity.

A commercial polymerase chain reaction (PCR) assay (Amplicor, Roche) for Chlamydia trachomatis was compared with a direct fluorescent antibody (DFA) test using urethral and cervical samples, many of which on the basis of prior testing by DFA contained small rather than large numbers of elementary bodies. Urine samples were collected from patients in a sequential unselected manner. Of 244 clinical specimens (138 male urethral and cervical; 106 male and female urine), 66 were positive by both DFA and PCR and 141 were negative by both tests. Nine samples were DFA negative and PCR positive, and 28 samples were DFA positive and PCR negative. However, 24 (86%) of the latter samples contained fewer than ten elementary bodies. When serial dilutions of laboratory stock strains (serovars E and H) were tested, the DFA test detected Chlamydia trachomatis at a dilution tenfold greater than the PCR. Furthermore, of five DFA-positive clinical samples, three that were PCR negative when tested according to the manufacturer's instructions were positive when they were diluted less. A modification of the PCR assay along these lines might improve sensitivity.

Chlamydia Infections↗
PubMed1995

Multiple frequency bioelectrical impedance for the prediction of total body potassium in cystic fibrosis.

The use of multiple frequency bioelectrical impedance analysis (MFBIA) was compared with single frequency bioelectrical impedance analysis (SFBIA) and anthropometry to estimate the size of the body cell mass (BCM) in a paediatric cystic fibrosis population. BCM was independently determined from the accepted gold standard reference of total body potassium (TBK). MFBIA was used to measure the impedance of the body at 248 frequencies from 4 kHz to 1 MHz. Data were analysed using Cole-Cole plots of reactance versus resistance. The limits of agreement procedure was used to determine the reliability and precision of the different techniques to predict values for TBK, in an individual subject. The results indicate that MFBIA with a precision of 12% offers little improvement over single frequency BIA but is better and more accurate than anthropometry for the prediction of TBK in an individual patient.

Journal Article↗
PubMed1995

The use of Cole-Cole plots to compare two multifrequency bioimpedance instruments.

Two commercially available multifrequency bioimpedance spectrometers (Xitron 4000B and SEAC SFB3) were compared by performing measurements on a set of electronic circuits and by studying 14 healthy volunteers. Output data were plotted as reactance versus resistance and fitted with a semi-circle using a least squares fitting program. In tests with six electronic circuits both instruments produced impedance loci that were well described by semicircular Cole-Cole plots, though there were some minor discrepancies using the Xitron instrument at frequencies above 150 kHz. When tested on the volunteers the SEAC instrument gave very good fits (RMSE = 1.5 Omega) to a semi-circle from 5-600 kHz on all volunteers. The Xitron instrument gave excellent fits to the semi-circle between 5 and 55 kHz (RMSE = 0.7 Omega) but above 55 kHz the phase measurements stayed constant or even increased, confirming the anomalous behaviour reported by other authors. The conclusions to be drawn are that the semicircular plots predicted by the Cole-Cole theory give a very good description of multifrequency impedance data recorded by the SEAC SFB3 instrument, on human subjects, for frequencies between 5 and 600 kHz. The Xitron 4000B is not able to reproduce the theoretically expected results in humans above 55 kHz.

Journal Article↗
PubMed1995

Infrequent detection of Chlamydia trachomatis in a longitudinal study of women with treated cervical infection.

OBJECTIVE: To determine how often Chlamydia trachomatis cervical infections are detected in women following completion of a currently recommended treatment regimen and the reason for recurrence. METHODS: A longitudinal follow-up study of 43 initially C trachomatis-positive women for periods of up to two years. RESULTS: C trachomatis was detected in three women, 19, 16 and about four months, respectively after completion of treatment. All specimens from the other 40 women which were taken during visits two to seven, that is periods of three to 700 days after treatment, were chlamydia-negative. CONCLUSION: Although C trachomatis is usually eradicated from the genital tract by conventional treatment, occasionally it may be found again. It is difficult to determine whether detection after treatment is due to persistence or reinfection and further studies are required.

Adult↗