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Biomedical subjects

M Thomas

Publications and source records attributed to M Thomas.

At least 415 records · Page 23Linked to original sources

HLA-A9 antibodies and epitopes.

Fifty pregnancy alloantisera directed towards HLA-A23 and/or A24 antigens were investigated serologically in titration studies against the three sequenced HLA-A9 specificities, A23 (A*2301), A24 (A*2402) and A2403 (A*2403). The reaction patterns of the antisera fell into five categories which allowed the three HLA-A9 specificities to be easily differentiated. Based on the various titre cytotoxicity scores of the antisera five possible antibody specificities were defined: anti-A23; -A24; -A23/24; -A24/2403 and anti-A23/24/2403. One antiserum crossreacted with HLA-A1 and A24. Inspection of the amino acid sequences of 136 HLA-A, B and C molecules allowed the prediction of five unique epitopes corresponding to these antibody specificities, a possible epitope unique to A2403 and confirmation of a likely epitope shared by A1 and A24. These, together with the previously suggested epitopes HLA-A9/ A2/A28 and A1/A23/A24 together with the presence of Bw4 on the three HLA-A9 antigens suggests that the HLA-A9 family of antigens is characterized by a minimum of nine serologically definable epitopes.

Antibodies↗

Distribution of the HLA-A9 antigen family (A23, A24 and A2403).

Characterization of 50 local anti-HLA-A9 (A23 and/or A24) sera against the HLA-A2403 antigen allowed the retrospective assignment of A2403 and the verification of A23 and A24 specificities in a panel of 9196 volunteer bone marrow donors. The six A2403 positive subjects identified were confirmed by PCR using four sequence-specific primer mixtures. Population analysis showed the distribution and HLA-A/B linkage disequilibrium of HLA-A23 and A24 to be typical of a Northern European Caucasoid population. HLA-A2403 has a phenotype frequency of 0.00065 (gene frequency-0.00033) and is in linkage disequilibrium with HLA-B63 and possibly B35.

Bone Marrow↗

Tardive dyskinesia associated with fluoxetine.

Three cases in which patients who were taking fluoxetine for relief of depression showed patterns of abnormal movements suggestive of tardive dyskinesia are presented. In the first case, abnormal facial movements began four weeks after fluoxetine was added to doxepin and lithium and remitted after fluoxetine was discontinued. In the second case, abnormal movements of the mouth and hands were noticed four years after the patient started taking fluoxetine and continued to be present a year after withdrawal of the medication. In the third case, orofacial dyskinesia that had remitted after withdrawal of sertraline and paroxetine and reappeared with fluoxetine was still present eight months after fluoxetine was withdrawn.

Adult↗

Recurrent aspergilloma of the frontoethmoid sinus in a non-immunocompromised patient.

Management of invasive aspergillosis of the paranasal sinuses requires sufficient experience to initiate appropriate investigations and then utilize the correct treatment protocol. Computed tomography (CT) or magnetic resonance imaging (MRI) is essential to show the extent of the disease and diagnosis is confirmed by histological analysis. Aspergillus flavus is a ubiquitous soil saprophyte in the Sudan and is responsible for many cases originating from this area. The literature is reviewed and treatment options discussed.

Adult↗

Major histocompatibility complex class II and complement polymorphisms in postpartum thyroiditis.

The objective was to re-evaluate the association between class II HLA-DR and DQ MIIC antigens and postpartum thyroiditis (PPT) and to determine the prevalence of the class III complement allotypes of Properdin factor B (Bf), C4A and C4B in this condition. Two hundred and sixty-five (of 2897) pregnant women screened positive for thyroid autoantibody activity took part. Further blood samples were obtained for HLA class II (185) and complement (193) typing. The severity of the ensuing PPT was assessed by measuring thyroid function during the postpartum year. The HLA-DR and DQ phenotypes were assigned from restriction fragment length polymorphism analysis, and Bf, C4A and C4B allotypes were determined by immunofixation with anti-Bf or anti-C4 antibodies after electrophoresis. A weak association between the HLA class II antigens and PPT, as indicated by a reduced frequency of DR15 and DQ6 together with an increased frequency of-DR5 and DQ7, was confirmed. However, only the change in DR5 frequency remained significant after correction (corrected p < 0.05). Postpartum thyroiditis was also associated with frequency disturbances in BI and C4A allotypes but not C4B allotypes. Whilst this study has not provided evidence of a strong marker gene for PPT, it does not preclude the involvement of the MIIC in this condition. These data show disturbances in complement allotype frequencies, suggesting that the class III region may provide a useful focus for further study of this pathology.

Complement C4a↗

Evaluation of three devices for self-measurement of blood pressure according to the revised British Hypertension Society Protocol: the Omron HEM-705CP, Philips HP5332, and Nissei DS-175.

OBJECTIVE: We evaluated three devices for self-measurement of blood pressure - the Omron HEM-705CP, the Philips HP5332 and the Nissei DS-175 - according to the revised protocol of the British Hypertension Society (BHS). The results were also analysed according to the criteria for accuracy of the revised standard of the Association for the Advancement of Medical Instrumentation (AAMI). DESIGN: The revised BHS protocol is divided into two parts. Part I, the part applicable to this study, comprises the main validation procedure and has five phases: Before-use device calibration; in-use (field) phase; after-use device calibration; static device validation; report of evaluation. METHODS: Three models of each device passed the before-use device calibration test, after which they entered the in-use phase, which involved use of the three recorders for a month; inter-device calibration was assessed again at the end of the month. There was no difference in calibration testing between the three models of each device, and therefore one of each was selected randomly; the main validation test was carried out in 85 subjects with a wide range of pressures, and the results were analysed according to the BHS grading system from A to D. RESULTS: The Omron HEM-705CP achieved an overall B/A grading and fulfilled the AAMI accuracy criteria; the Philips HP5332 achieved an overall C/A grading and failed the AAMI accuracy criteria for measuring systolic pressure; the Nissei DS-175 achieved an overall D/A grading and failed the AAMI accuracy criteria for measuring systolic pressure. When the BHS and AAMI criteria were applied to tertiles of pressure (low-pressure range < 130/80 mmHg; medium-pressure range 130-160/80-100 mmHg; high-pressure range > 160/100 mmHg) all three devices were less accurate in the high-pressure range: the Omron HEM-705CP achieved C/B grading while continuing to fulfil the AAMI criteria; the Philips HP5332 dropped to D grading for systolic pressure and the Nissei DS-175 achieved a lower D grading for systolic pressure. The mean and standard deviation of the first mercury sphygmomanometer measurements were 148+/-35/88+/-22 mmHg. Acceptability by the users was good and the manufacturer's manual was satisfactory for all three devices. CONCLUSIONS: On the basis of these results, the Omron HEM-705CP was the most accurate of the three devices tested, achieving Grade B for systolic and Grade A for diastolic pressure, as well as fulfilling the AAMI criteria for accuracy for both systolic and diastolic pressure. It can therefore be recommended for the clinical measurement of blood pressure and is the first inexpensive device to satisfy the accuracy criteria of these protocols.

Journal Article↗

Planes, kangaroos, and the CAPD manual.

The Western Australian (WA) Remote Area Dialysis Programme was developed in 1988 due to the cultural need to dialyze an increasing number of aboriginal patients in their own communities, rather than relocating them up to 3000 km away in Perth. The success of the program relies on remote area health services (RAHS), which have no prior experience in continuous ambulatory peritoneal dialysis (CAPD), providing consistent routine and emergency medical care to the patients. Our aim was to standardize the care of all CAPD patients in remote WA by providing the RAHS with an easy-to-follow manual. Although the RAHS received treatment protocols, and in-service education, consistent care was not always provided. We confirmed this by: (1) examining the existing quality assurance tools, peritonitis and hospital admission rates, (2) discussion with remote area staff regarding patients, and (3) informal assessment of remote area staff receptiveness to in-service education by a CAPD nurse. We identified the causes of the inconsistent care to be: (1) high remote area staff turnover (six months average for a registered nurse), (2) the protocols were difficult to follow, and (3) confusion for the RAHS as to the appropriate contact person at our hospital. In 1994, the situation was exacerbated by the dramatic increase in the number of patients and RAHS involved (14 new patients, bringing the total to 20 patients in 12 centers) plus the introduction of a second treating hospital (with differing protocols). A team of two CAPD nurses and two nephrologists was established, to collaborate with two remote area hospitals and the second treating hospital to produce the "Remote Area CAPD Manual." The manual is an easy-to-follow, step-by-step guide for the management of CAPD by non-dialysis personnel. It has led to improved management of CAPD, improvement in communication with RAHS, and the increased confidence of remote area staff in the management of CAPD patients. In conclusion, RAHS can give consistent care if provided with clear, concise guidelines.

Adult↗

The potential thrombogenic action of a nonionic radiographic contrast medium used during coronary angiography is offset by heparin during coronary angioplasty.

Iohexol sodium, a nonionic radiographic contrast medium, used in invasive imaging techniques has been shown to be potentially thrombogenic. In the present study, the effect of iohexol sodium on haemostatic factors was evaluated in 20 patients, 16 male and 4 female, 10 undergoing coronary angiography and another 10 undergoing coronary angioplasty. All the patients had angiographically-assessed coronary artery disease. The patients undergoing coronary angioplasty received a significantly larger quantity of the dye as compared with the patients undergoing coronary angiography. The former group of patients also received a bolus of 20,000 units of standard heparin in addition. The levels of thrombin-antithrombin-III complex (TAT), prothrombin fragments 1 and 2 (F1F2), D-dimer and the functional activity of tissue factor pathway inhibitor (TFPI) were assayed. While the baseline and 30-min post-dye levels of TAT and F1F2 were comparable in patients undergoing coronary angioplasty, the 30 min levels were significantly elevated in patients undergoing coronary angiography. The post-dye levels of TFPI activity were significantly increased in the former group due to the heparin-induced release of TFPI. It is concluded that the thrombogenic potential of iohexol sodium was overcome by heparin used routinely during coronary angioplasty.

Angioplasty, Balloon, Coronary↗

Serological and molecular identification of an HLA-B8 variant, HLA-B8Jon (B*0802).

The serological and molecular characteristics of the first HLA-B8 variant (B8Jon), located on a haplotype bearing HLA-A1, -B8Jon, -Cw*07, DRB1*0301, DQA1*05, DQB1*0201, BfS, C4AQ0, C4B1 and the microsatellite alleles D6S265-3, 258-11, 105-8, 299-1 and 202-2 are identified and described. This new HLA-B antigen was distinguished from the usual B8 by its lack of reactivity with Bw6 and most Bw4 antisera, together with its failure to react with most antisera cross-reactive with HLA-B8. B8Jon gives a 'weaker' response than HLA-B8 in titration studies with B8 antisera. It cannot be differentiated from the usual B8 by one-dimensional iso-electric focusing. Time course studies, absorption analyses and serological tests on 17 Bw4 antibodies suggest that B8Jon possesses an unusually 'weak' Bw4 epitope. Studies on the Bw4 sequence motif by PCR, using sequence-specific primers, indicate that B8Jon has a Bw4 sequence in common with other HLA-B alleles, including B*4402-B*4405, rather than the Bw6 motif found on the familiar HLA-B8 molecule.

DNA↗