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Biomedical subjects

B J Thomas

Publications and source records attributed to B J Thomas.

At least 127 records · Page 7Linked to original sources
PubMed1991

Shoulder arthroplasty for rheumatoid arthritis.

Forty-two Designed After Natural Anatomy (DANA) total shoulder arthroplasties (Howmedica, Rutherford, New Jersey) were performed in 34 rheumatoid patients. Thirty shoulders in 23 patients were followed for a minimum of two years. Twelve of the 30 shoulders (40%) had significant rotator cuff tears. The average rating for pain improved from 3 points preoperatively to 8 points postoperatively for the overall group, and the average rating for function improved from 3 points preoperatively to 6 points postoperatively. Range of motion (ROM) improved substantially in patients treated with a regular glenoid component. Four patients were treated with hooded glenoid components designed to improve stability for shoulders in which the rotator cuff was deficient. In the rotator-cuff-deficient patients, pain and function improved; however, ROM was unchanged. Complications, including one acromial fracture and two loose glenoid components, required revision surgery.

Aged↗
PubMed1991

Total knee arthroplasty in rheumatoid arthritis. A comparison of the polycentric and total condylar prostheses.

From 1971 to 1985, 393 total knee arthroplasties (TKAs) were performed in patients for rheumatoid arthritis. Of these, 112 used polycentric prostheses and 131 used total condylar prostheses. One hundred seven of the patients with polycentric prostheses and 102 of the patients with total condylar prostheses were followed for a minimum of two years (average, 61 and 55 months, respectively). At the time of the latest examination, nine knees with polycentric prostheses required revision surgery: six for tibial component loosening and instability and three for patellofemoral pain. Five knees with total condylar prostheses required revision: one for chronic instability, one for a late posttraumatic patellar fracture, and three for late hematogenous infections. The total condylar prostheses with patellar resurfacing had better scores for pain (8.5 points) than the polycentric prosthesis without patellofemoral resurfacing (7.0 points). The total condylar prosthesis appeared more durable in terms of fixation, with no evidence of aseptic loosening of femoral or tibial components noted in this series thus far.

Arthritis, Rheumatoid↗
PubMed1990

Postoperative irradiation for the prevention of heterotopic bone: analysis of different dose schedules and shielding considerations.

Ninety-seven high risk hips were irradiated postoperatively for prevention of heterotopic bone (HTB) in the UCLA Department of Radiation Oncology from 1980 to 1988. Ninety-two hips in 82 patients were eligible for analysis with a minimum follow-up of 2 months and a median follow-up of 10 months. Forty-nine of the hips had porous coated ingrowth prostheses. From 1980 to 1986, 2 Gy fractions were used to deliver 20 Gy (8 hips), 12 Gy (1 hip), and 10 Gy (27 hips). Since December of 1986, 38 hips received 8 Gy in two increments and 18 hips received a single 7 Gy fraction. All porous ingrowth components were shielded with custom blocks. Six out of 92 hips developed clinically significant (Brooker grade 3 or 4 heterotopic bone). There was one clinically significant failure in 78 hips (1.3%) when irradiation was initiated before post-operative day (POD) #6 and shielding was properly placed. One clinical failure occurred in 38 hips which received 8 Gy in two increments. One clinical failure occurred out of the 18 hips treated with 7 Gy in one fraction. This failure could be related to block malposition. There were four clinical failures in the 36 hips treated with 2 Gy fractions to total doses of 10 Gy, 12 Gy, or 20 Gy. Three of these failures were associated with initiation of treatment after POD #5, and the fourth was related to block malposition. Unshielded trochanteric osteotomies resulted in five migrations and seven fibrous unions for a total non-osseous union rate of 12/36 (33%). Shielding of the remaining 28 trochanteric osteotomies resulted in a non-osseous union rate of 7% (0 migrations and 2 fibrous unions). There were no failures of union of components, and the only side effects noted in the series were the five trochanteric migrations. In conclusion, the use of 8 Gy in two increments or 7 Gy in one fraction was found to be as efficacious as conventional 2 Gy fractionation schemes with no increase in side effects. For optimal results, treatment should be implemented prior to POD #5 with shielding of the trochanteric osteotomy. Postoperative irradiation to prevent HTB can be used in hips with porous components using properly placed blocks to shield the porous region.

Adolescent↗
PubMed1990

Leaf Senescence in a Nonyellowing Mutant of Festuca pratensis: Metabolism of Cytochrome f.

In a mutant genotype of Festuca pratensis Huds., net degradation of a number of thylakoid membrane proteins during senescence is impaired. Previous studies have suggested that the highly hydrophobic intrinsic chlorophyll-binding proteins were the definitive subjects of the metabolic lesion. In the present study we find that cytochrome f, as determined by haem-staining, Western blotting, enzyme-linked immunosorbent assay, and immunogold electron microscopy, is also abnormally stable in the mutant. The structural feature common to all the proteins in the mutant so far recognized to be abnormally stable is possession of a tetrapyrrole prosthetic group. It is suggested that degradation of chlorophyll and haem may regulate degradation of the associated apoproteins, and hence has an important role to play in membrane protein turnover and in mobilisation of amino acids during chloroplast disassembly.

Journal Article↗
PubMed1990

A 2-year quantitative assessment of Chlamydia trachomatis in a sexually transmitted diseases clinic population by the MicroTrak direct smear immunofluorescence test.

The MicroTrak direct smear immunofluorescence test was used to determine the prevalence of Chlamydia trachomatis elementary bodies (EBs) in groups of patients in various clinical categories, most of whom were seen in a clinic for sexually transmitted diseases (STD). Overall, 8138 adequate specimens were tested, of which 14.3% were found to contain chlamydial EBs. Of the samples from patients seen in the STD clinic, over 70% were from women and 14.9% of these were positive, as were 15.7% of those from men. EBs were detected in 27% of samples from infants and in 7.0% of those from adults with conjunctivitis. EBs were detected most often in men with nongonococcal urethritis (40.2%), infants with conjunctivitis (30%) and contacts of chlamydiae-positive patients (24.5%) and least often in 'prostatitis' (2.9%) and patients tested to determine the success of treatment (2.7%). Over 40% of samples from both the male urethra and the cervix contained 10 or fewer EBs, highlighting the importance of recognizing small numbers and the sensitivity required of other detection procedures.

Adult↗
PubMed1990

The Masters Degree in Medical Physics at Queensland University of Technology--14 years on.

In 1975, the Masters Degree in Medical Physics was first made available at the Queensland Institute of Technology (now Queensland University of Technology, QUT), and is offered on both a part time and full time basis. An option for a Graduate Diploma award after completion of the in-house course work stage is available. The research project may be undertaken either in Brisbane or elsewhere. Such projects have been undertaken in Perth, Hong Kong, Sydney, etc. It is a broad based program, embracing activities of current professional importance while including aspects which have potential importance. Recognition that medical physics is a dynamic speciality ensures that the content of the program is kept under continuous review, and changes made as required. It is of interest to observe that of graduates from the course, approximately 50% have moved into the hospitals and private medical research, 11% into government health departments, 16% into the mining industry, 9% into tertiary education, and 14% into non medical or sales areas. Many have gained senior positions in their selected vocations. The success of the program in providing a useful professional person is due in no small measure to the collaboration of many dedicated professionals in the field. This collaboration relates to informal and formal contact between academic staff and students within the Physics Department, and personnel in hospitals, public health establishments and industry.

Biophysics↗
PubMed1989

Elevated recombination rates in transcriptionally active DNA.

We have examined the effect of RNA polymerase II-dependent transcription on recombination between directly repeated sequences of the GAL10 gene in S. cerevisiae. Direct repeat recombination leading either to plasmid loss or conversion was examined in isogenic strains containing null mutations in the positive activator, GAL4, or the repressor, GAL80. A 15-fold increase in the rate of plasmid loss is observed in cells constitutively expressing the construct compared with cells that are not. Conversion events that retain the integrated plasmid are not stimulated by expression of the repeats. Northern analysis of strains containing plasmid inserts with various promoter mutations suggests that the stimulation in recombination is mediated by events initiating within the integrated plasmid sequences.

Crossing Over, Genetic↗
PubMed1989

The role of Chlamydia trachomatis in chronic abacterial prostatitis: a study using ultrasound guided biopsy.

We studied 50 patients with chronic abacterial prostatitis as defined by the Stamey procedure via transrectal prostatic ultrasound and subsequent transperineal biopsy of the abnormal areas of the prostate to ascertain the role of Chlamydia trachomatis organisms (chlamydiae) in this condition. Chlamydiae were detected by an immunofluorescence technique in the urethra of 1 patient (2 per cent) but they were not recovered in McCoy cell culture from the prostatic tissue of any patient nor were they detected in the tissue by immunofluorescence. In addition, serum antibody to Chlamydia trachomatis was not found even in moderate titer. The approach in this study has overcome the problem of urethral contamination in the assessment of prostatic specimens from patients with chronic abacterial prostatitis. There is no evidence that chlamydiae are directly implicated in the disease, although the possibility of an earlier active role cannot be excluded.

Adult↗
PubMed1989

The genetic control of direct-repeat recombination in Saccharomyces: the effect of rad52 and rad1 on mitotic recombination at GAL10, a transcriptionally regulated gene.

We have previously shown direct-repeat recombination events leading to loss of a plasmid integrated at the GAL10 locus in Saccharomyces cerevisiae are stimulated by transcription of the region. We have examined the role of two recombination- and repair-defective mutations, rad1 and rad52, on direct repeat recombination in transcriptionally active and inactive sequences. We show that the RAD52 gene is required for transcription-stimulated recombination events leading to loss of the integrated plasmid. Similarly, Gal+ events between the duplicated repeats that retain the integrated plasmid DNA (Gal+ Ura+ replacement events) are reduced 20-fold in the rad52 mutant in sequences that are constitutively expressed. In contrast, in sequences that are not expressed, the rad52 mutation reduces plasmid loss events by only twofold and Gal+ Ura+ replacements by fourfold. We also observe an increase in disome-associated plasmid loss events in the rad52 mutant, indicative of chromosome gain. This event is not affected by expression of the region. Plasmid loss events in rad1 mutant strains are reduced only twofold in transcriptionally active sequences and are not affected in sequences that are repressed. However, the rad1 and rad52 double mutant shows a decrease in plasmid loss events greater than the sum of the decreases in the rates of this event displayed by either single mutant in both constitutive and repressed DNA, indicating a synergistic interaction between these two genes. The synergism is limited to recombination since the rad1 rad52 double mutant is no more sensitive when compared with either single mutant in its ability to survive radiation damage. Finally, the recombination pathway that remains in the double mutant is positively affected by transcription of the region.

DNA Repair↗
PubMed1989

Total body potassium in cystic fibrosis.

To further evaluate the nature of malnutrition, define at-risk groups, and confirm the efficacy of nutritional supplementation on body composition in cystic fibrosis (CF), we have conducted longitudinal and cross-sectional studies of total body potassium (TBK) in 161 unselected CF subjects aged 1 month to 17 years. TBK was determined by measurement of 40K in a whole body counter, reflecting body cell mass (BCM), the vital work-performing and growing cellular component of the body. Compared with normal TBK data for age and sex from pooled measurements of 1,629 healthy children aged 1 week to 17 years, CF infants (n = 12) diagnosed by newborn screening were depleted in TBK at diagnosis and showed catch-up with therapy by 1 year; CF children aged 2-17 years (n = 140) showed a tendency for inadequate accretion of TBK (and thus BCM) with increasing age, although the normal correlation between TBK and weight and height was maintained in the majority suggesting a pattern of nutritional stunting of growth; and malnourished CF children (n = 9) showed significant catch-up in TBK with long-term nutritional rehabilitation (85-98% of TBK predicted for weight and height). These studies suggest that potentially serious, but possibly correctable deficits, in the growth of the body cell mass as measured by TBK occur commonly in CF. These deficits may be established very early in life and if not corrected lead to progressive nutritional growth retardation with increasing age.

Adolescent↗
PubMed1989

Acute epididymitis: a microbiological and ultrasonographic study.

In a prospective study of 24 men (mean age 28.3 years) with acute epididymitis who underwent epididymal aspiration, micro-organisms were detected in 15 (62.5%). Chlamydia trachomatis accounted for 10 (42%) of the cases, being located in both the urethra and epididymis in 5 individuals. Chlamydial serology supported the diagnosis of chlamydial infection, there being a strong correlation between the detection of C. trachomatis and elevated titres of both chlamydial IgG and IgM antibodies. In 4 patients (mean age 55.5 years), Escherichia coli was cultured from both mid-stream urine and epididymal aspirate. Transrectal ultrasound revealed abnormal prostatic scans in 19 patients (79%). These data confirm the aetiological role of C. trachomatis, support the notion that micro-organisms spread intra-canalicularly and suggest that the prostate is also involved in the inflammatory process in acute epididymitis.

Acute Disease↗
PubMed1989

A search for infectious agents in chronic abacterial prostatitis using ultrasound guided biopsy.

A series of 60 patients with a diagnosis of chronic abacterial prostatitis, as defined by the Stamey procedure, was studied by transrectal prostatic ultrasound and subsequent transperineal biopsy of the abnormal areas of the prostate in order to ascertain the role of micro-organisms in this condition. Histological assessment revealed a chronic inflammatory infiltrate, generally of low grade, in 53 patients (88%). Organisms were isolated from the prostatic tissue of only 9 patients (15%) and were considered to be contaminants from the perineal skin, since treatment with an appropriate antimicrobial agent failed to alter symptoms or affect the leucocyte count in the urine or prostatic fluid. Chronic abacterial prostatitis may be a non-organismal inflammatory process.

Adult↗
PubMed1989

Improved sensitivity of an enzyme immunoassay IDEIA for detecting Chlamydia trachomatis.

In tests on 375 genital tract specimens a commercially available enzyme immunoassay for Chlamydia trachomatis (IDEIA; Boots-Celltech) was found to have sensitivity values of 62% for men and 74% for women, and a specificity of 97% for both groups, relative to the results obtained by a fluorescence assay (Micro Trak; Syva). The positive predictive value and the negative predictive value of the immunoassay were 91% and 87%, respectively. Collection of samples for IDEIA in transport medium in plastic phials, as opposed to glass phials recommended by the manufacturer, had no effect on these values. Tests of the sensitivity of IDEIA using laboratory strains of C trachomatis showed that the assay detected chlamydial elementary bodies only at dilutions at least 10-fold lower than those at which they could be detected by Micro Trak. Tests of the specificity of the assay with microorganisms found in the genital tract, other than chlamydiae, showed that reactions occurred with a number of these. Testing three cervical swabs from the same patient, with the material taken into a single phial of transport medium, increased the sensitivity of IDEIA from 74% to 96%, without reducing the specificity which remained at 97%. It is concluded that this approach enchances the value of the test in a sexually transmitted disease clinic population and may do so in a population with a low prevalence of chlamydiae.

Chlamydia trachomatis↗
PubMed1989

Lack of effect of selenium on induction of tumors of esophagus and bladder in rats by two nitrosamines.

The effect of differences in level of dietary selenium on the induction of esophageal and bladder tumors in rats by two nitrosamines was investigated. Groups of 20 female F344 rats were given a synthetic diet containing less than 0.05 ppm Se to which selenium (as sodium selenite) was added at the concentration of 0.35, 0.7, 1.4 and 2.1 ppm selenium. These four groups, plus one without added Se, were treated with 20 ml per rat per day, 5 days a week, of a solution of nitrosomethylcyclohexylamine containing 5 mg/liter. A parallel five groups were treated in the same way with a solution of nitrosomethyl-3-carboxypropylamine in drinking water containing 600 mg per liter, as drinking water. Treatment lasted 28 weeks, at which time some animals had developed tumors. A group of 20 rats fed 0, 1.4 and 2.1 ppm Se was not treated with carcinogen. Rats consuming 1.4 ppm or 2.1 ppm Se gained weight more slowly than other groups. There was no significant difference in survival between the five groups treated with each carcinogen but receiving different dietary levels of selenium. Neither was there any significant difference between groups receiving each carcinogen in the incidence of tumors of the esophagus induced by nitrosomethylcyclohexylamine or of tumors of the urinary bladder induced by nitrosomethylcarboxypropylamine. Control rats on the synthetic diets did not survive as well as untreated rats eating regular chow diet. In these conditions there was no effect of dietary selenium levels on the induction of tumors in female rats by the two carcinogenic nitrosamines we used.

Animals↗
PubMed1988

Carcinogenesis by nitroso-2-hydroxyethylurea in splenectomized hamsters.

Several nitrosoalkylureas tested for carcinogenic activity in Syrian hamsters have as their main effect the induction of hemangiosarcomas of the spleen, many of which appear to metastasize to the liver. To investigate whether any of these lesions in the liver might not be metastases, a group of female Syrian hamsters was surgically splenectomized and treated with nitroso-2-hydroxyethylurea (NHEU) dissolved in corn oil/ethyl acetate once a week for 22 weeks. The animals survived much longer (median 45 weeks) than a comparable group of unsplenectomized female hamsters given identical treatment (median 24 weeks). The absence of hemangiosarcomas of the liver in the splenectomized hamsters showed that the presumed metastases seen in intact animals were, in fact, just that. A second interesting conclusion is that the compound did not produce a concomitant increase in tumors of other types.

Animals↗
PubMed1988

Inflammatory joint disease and human immunodeficiency virus infection.

Nine men positive for antibody to human immunodeficiency virus (HIV) who developed peripheral, non-erosive arthritis were followed up. The clinical features were compatible with reactive arthritis but were atypical in several respects: the joint symptoms were generally severe, persistent, and unresponsive to non-steroidal anti-inflammatory drugs. The onset of arthritis was associated with various infections, none of which are known to be associated with the development of reactive arthritis. HLA typing was performed for three patients, all of whom were positive for HLA-B27. HIV was isolated from the synovial fluid of one patient. No patient had AIDS before developing arthritis, but four progressed to having AIDS after a mean of 7.5 months, and two died. Arthritis resolved in only one patient. The possibility of HIV infection should be considered in all patients with conditions suggesting reactive arthritis. Synovitis in patients with severe immunodeficiency has important pathogenetic implications.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1988

Alkylation of DNA in rats by N-nitrosomethyl-(2-hydroxyethyl)amine: dose response and persistence of the alkylated lesions in vivo.

The in vivo alkylation of DNA by N-nitrosomethyl-(2-hydroxyethyl)amine (NMHEA) was examined in male and female F-344/N rats. NMHEA is a strong hepatocarcinogen in female rats when administered by gavage but a weaker hepatocarcinogen in male rats. Groups of 5 rats of each sex were treated by gavage with various doses of NMHEA dissolved in corn oil. After 4 h the animals were sacrificed and the livers, lungs, and kidneys were removed. The DNA from each liver was isolated and the neutral thermal and mild acid hydrolysates were separated by high-performance liquid chromatography. The alkylated guanines were quantified by fluorescence spectroscopy. NMHEA gives rise to four fluorescent alkylated guanines, 7- and O6-methylguanines, and 7- and O6-hydroxyethylguanines. The dose-response data revealed that all four lesions increased with dose. There was approximately 10x more methylation than hydroxyethylation at the 7 position of guanine. There was less O6 alkylation, but both methylation and hydroxyethylation were observed at all of the doses studied. The overall alkylation was the same in males and females at the 10- and 20-mg/kg doses, but at higher doses the females exhibited significantly higher levels of alkylation than males. The level of alkylation of DNA isolated from non-target tissues, lung, and kidney was low. The persistence of these lesions in vivo was studied at a dose of 25 mg/kg. Groups of five animals each were sacrificed at various times from 0 to 96 h. There was no significant difference between the sexes in persistence of any of the lesions in the liver. The 7-alkylguanines disappeared slowly over the observation period. 7-Methylguanine was present at 30% of the maximum level after 96 h, while 7-hydroxyethylguanine appeared to be more stable. The O6-alkylguanines were removed rapidly from the liver, being at base level by 48 h. The rapid removal of O6-hydroxyethylguanine suggests a repair process independent of O6-alkylguanine-DNA guanine alkyl transferase: an excision repair is postulated. In vitro alkylation of calf thymus DNA by N-nitrosomethyl-(2-tosyloxyethyl)amine, a surrogate for the putative O-sulfate conjugate of NMHEA, resulted in exclusive methylation of DNA-guanine at both the 7 and O6 positions; no hydroxyethylation was detected. In vitro alkylation of calf thymus DNA with 2-hydroxyethyl-ethylnitrosourea resulted in exclusive hydroxyethylation of DNA-guanine at the 7 and O6 positions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗