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Biomedical subjects

D Thomas

Publications and source records attributed to D Thomas.

At least 667 records · Page 37Linked to original sources
PubMed1989

Diagnosis of coronary aneurysms in siblings: treatment with a new surgical procedure.

We report the cases of two brothers who simultaneously developed myocardial infarction, and in whom we found coronary artery aneurysms at echocardiography. In one case a new surgical procedure was performed. The aneurysm was bypassed by an aorto-coronary vein graft and the coronary ostium of the related coronary artery was closed. Thus, perfusion of the dependent vessels of the aneurysm was maintained, and the risk of distal embolism was prevented. The aetiologies of coronary artery aneurysms are discussed. In our patients the aneurysms were probably congenital, but we cannot exclude the possibility of previously undiagnosed Kawasaki's disease.

Adult↗
PubMed1989

Objective documentation of musculoskeletal pain syndrome by pressure algometry during thiopentone sodium (Pentothal) anesthesia.

Work and injury related musculoskeletal pain is often complicated by psychological and medicolegal factors that obscure the validity of the pain presentation. Pressure algometry and stretching during thiopentone sodium (Pentothal) anesthesia was studied in 45 cases of musculoskeletal injury. A total of 40 cases were determined as genuine, organic pain, four cases were negative (i.e., nonorganic pain), and one case was equivocal. In unilateral pain cases, a right to left pressure threshold difference of 2.0 kg/cm2 predicted 94% of true organic pain cases and 100% of cases at a pressure threshold of 1.5 kg/cm2 if combined with stretching. Results of stretching painful areas correlated highly with pressure threshold assessments.

Achilles Tendon↗
PubMed1989

Outpatient methadone programme for pregnant heroin using women.

A prospective study of pregnant narcotic users who attended the antenatal clinic at Westmead Hospital was undertaken to determine the practicality and safety of an outpatient methadone programme for these women. Forty-six women were commenced and managed on a methadone maintenance programme based at the Drug and Alcohol Clinic at Westmead Hospital (GROUP I), 12 women were maintained on long-term methadone therapy by outside prescribers (GROUP II), 12 women not on methadone continued to use heroin through the pregnancy (GROUP III), 14 women used heroin intermittently (GROUP IV). These were compared with a group of 52 women who were non-drug using (GROUP V). Women on the hospital based methadone programme had an earlier first antenatal clinic visit (p less than 0.001) than those women on outside methadone programmes or on heroin and had a longer pregnancy (p less than 0.001) than those women on heroin. The birth-weights on babies delivered to women on the Westmead Methadone Programme were significantly higher than those on babies born to women using heroin (p less than 0.05). A disappointing aspect of the study was a lower number of antenatal clinic visits (p less than 0.001) for all narcotic using women when compared with the comparison group. The outcome of the Westmead Methadone Programme women showed that better maternal and neonatal outcome followed entry into a hospital monitored methadone programme with attendant antenatal care.

Adult↗
PubMed1989

Physiological and Morphological Modifications in Immobilized Gibberella fujikuroi Mycelia.

Constraints created by immobilization conditions modified the physiological behavior and morphological characteristics of Gibberella fujikuroi mycelia in comparison with their development in free-cell conditions. G. fujikuroi mycelia were immobilized in different support matrices (polyurethane, carrageenan, and alginate) and showed a variety of reactions in response to the different microenvironmental factors encountered during and after immobilization. The best support with respect to gibberellic acid yield and biocatalyst stability was found to be an alginate with a high degree of polymerization. The most visible effects of immobilization included changes in growth development, morphological appearance, metabolite production, mycelial pigmentation, mycelial viability under starvation conditions, and induction of resting forms when previously immobilized mycelia were subcultured.

Journal Article↗
PubMed1989

In vitro and in vivo activity of polyclonal and monoclonal human immunoglobulins G, M, and A against Pseudomonas aeruginosa lipopolysaccharide.

We evaluated the in vitro opsonophagocytic killing activity of monoclonal human immunoglobulin G (IgG), IgM, and IgA specific for Pseudomonas aeruginosa lipopolysaccharide and the in vivo protective capacity in neutropenic mice of both monoclonal and purified polyclonal IgG, IgM, and IgA. Monoclonal IgM was efficacious in mediating opsonophagocytic killing only in conjunction with complement, whereas monoclonal IgG opsonic killing was potentiated by complement, and monoclonal IgA opsonic killing was independent of complement. These findings are similar to those previously reported for purified polyclonal IgM, IgG, and IgA. The monoclonal and polyclonal immunoglobulins had comparable 50% protective doses in neutropenic mice (range, 0.28 to 0.46 microgram per mouse). The protective activity of IgM in neutropenic mice was abolished by cobra venom factor treatment, whereas IgG and IgA maintained efficacy in cobra venom factor-treated mice. These data indicate that all three major human serum immunoglobulin isotypes have opsonophagocytic and protective activities against P. aeruginosa, with a critical role for complement in the function of IgM.

Animals↗
PubMed1989

Elements involved in S-adenosylmethionine-mediated regulation of the Saccharomyces cerevisiae MET25 gene.

In Saccharomyces cerevisiae, the MET25 gene encodes O-acetylhomoserine sulfhydrylase. Synthesis of this enzyme is repressed by the presence of S-adenosylmethionine (AdoMet) in the growth medium. We identified cis elements required for MET25 expression by analyzing small deletions in the MET25 promoter region. The results revealed a regulatory region, acting as an upstream activation site, that activated transcription of MET25 in the absence of methionine or AdoMet. We found that, for the most part, repression of MET25 expression was due to a lack of activation at this site, reinforced by an independent repression mechanism. The activation region contained a repeated dyad sequence that is also found in the promoter regions of other unlinked but coordinately regulated genes (MET3, MET2, and SAM2). We show that the presence of the two dyads is necessary for maximal gene expression. Moreover, we demonstrate that in addition to this transcriptional regulation, a posttranscriptional regulation, probably targeted at the 5' region of mRNA, is involved in MET25 expression.

Base Sequence↗
PubMed1989

Dissociation of immunocomplexes by ionic shock for the development of immunosensors: application to measurement of alpha 1-fetoprotein.

We report here our experimental results on the reaction rate of immunological complexes and on potential repeated use of membranes as a result of dissociation of the complexes between alpha 1-fetoprotein and catalase-labeled antibodies by different buffers with various ionic strengths. The measurement consists of an immunological process and an enzymatic reaction. The protein membrane activated by glutaraldehyde for the immobilization of antibodies is fixed over an oxygen electrode. After incubation with antibody/alpha 1-fetoprotein and antibody/alpha 1-fetoprotein antibodies coupled to catalase, the reaction medium is introduced into a continuous-flow cell. Oxygen production by the catalase is measured on-line, with the electrode in contact with hydrogen peroxide. This response is correlated to the alpha 1-fetoprotein concentration of the sample. We show a typical calibration curve between 0.5 and 120 micrograms/L. Replicate (n = 20) equilibrium measurement with the same membrane gave a CV of 2.2%. The reversible immunochemical sensor has been tested for 30 measurements without significant loss of activity.

Antigen-Antibody Complex↗
PubMed1989

[Infective endocarditis of a valve prosthesis. Multicenter study (179 cases)].

Over a 5-year period (1982-1986) 176 cases of infective endocarditis on prosthesis (IEP) were recorded in 40 cardiology departments. 65 p. 100 of the patients were male, and the mean age of the population was 51 years. Mechanical prostheses were involved in 57 p. 100 of the cases and bioprosthesis in 43 p. 100. There was a high proportion of initial indications for bacterial endocarditis (18 p. 100) and for reoperation on prosthesis (10 p. 100). IEP developed early in 40 cases and late in 139 cases; 19 (48 p. 100) of the early IEPs were staphylococcal, while 31 p. 100 of late IEPs were streptococcal (p less than 0.01). 143 patients were reoperated upon within less than 1 month in 41 p. 100 of the cases, with a pre-operative antibiotic therapy of less than 10 days in 39 p. 100. Reoperation was performed in stage IV or as an emergency in 45 p. 100 of the cases. Abscesses were three times more frequent with aortic prostheses than with mitral prostheses (58 p. 100 vs 20 p. 100, p less than 0.001). Vegetations were more frequent on mechanical prostheses than on bioprostheses (43 p. 100 vs 31 p. 100, NS). The operative mortality rate was 25 p. 100; the mortality rate of unoperated patients was even higher (31 p. 100). The survival rate in operated IEP was 51 p. 100 at 30 months, as against 46 p. 100 at 12 months in unoperated IEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Prevalence of patent foramen ovale in young patients with ischemic cerebral complications].

We compared the prevalence of patent foramen ovale (PFO), detected by two-dimensional contrast echocardiography, in a group of 60 adults aged under 55 who had experienced a cerebral ischaemic accident and had normal standard examination of the heart, and in a control group of 100 patients. The prevalence of PFO was significantly higher in neurological patients (40 p. 100) than in controls (10 p. 100; p less than 0.001). Within the neurological group, the prevalence of PFO determined blindly, i.e. without any knowledge of the aetiological diagnosis, increased with the uncertainty of diagnosis: 21 p. 100 when a cause could be determined (n = 19), 40 p. 100 when a facilitating factor of cerebral accident, such as mitral valve prolapse, migraine or consumption of oral contraceptives, could be identified (n = 15), and 54 p. 100 when neither cause nor facilitating factor could be found (n = 26; p less than 0.10). In view of the very high prevalence of clinically silent venous thrombosis, these results suggest that paradoxical embolism through a PFO might be responsible for cerebral ischaemic accidents more frequently than is generally believed.

Adult↗
PubMed1989

[Evolution of the primary successes of percutaneous aortic valvuloplasty].

Between November 1985 and August 1988, we performed 89 percutaneous aortic valvuloplasties. Sixty-two of these were considered a primary success on the basis of two main criteria: stage I or II on discharge and greater than 50 p. 100 increase in aortic valve area. The mean age of these patients was 78.4 +/- 6.1 years. On actuarial analysis, after 5 months 98 p. 100 of the patients with primary success were alive and 89 p. 100 were in stage I or II and had not been operated upon or redilated. At 15 months 79 p. 100 of the patients with primary success were alive, but only 48 p. 100 were in stage I or II and neither operated upon or redilated. Ultrasonic data obtained one and twelve months after dilatation were compared in 8 patients who had kept the full functional benefit of angioplasty for 14.6 +/- 4.3 months (group 1) and 9 patients who had lost this initial benefit (group 2). In group 1 patients the aortic valve area had moderately and non significantly diminished from 0.92 to 0.72 cm2. In group 2 patients the aortic valve area had gone down from 0.89 to 0.63 cm2 (p less than 0.01), indicating restenosis. We conclude that after the 4th post-valvuloplasty month the medium-term success of the procedure undergoes some degradation, and in these patients the echocardiographic signs of stenosis are clear-cut.

Aged↗
PubMed1989

[Interstitial tubulo-nephritis and uveitis (Nitu syndrome). Apropos of a case].

Acute renal failure due to tubulo-interstitial nephritis developed in a 12 year old boy. It was accompanied by an inflammatory syndrome consisting of a markedly increased erythrocyte sedimentation rate and high levels of C. reactive protein and fibrin. The association of these anomalies with an uveitis are typical of the Tinu syndrome (tubulo-interstitial nephritis uveitis) first described by Dobrin and al. in 1975. The interest of this case lies in the observation of focal chorioretinitis, as yet never described. The possibility of toxoplasmosis is discussed; it could be a direct etiologic factor or could represent a concurrent phenomenon. However no evidence of toxoplasmic infection could be demonstrated in this case, nor in any case previously reported. Light microscopic examination of a renal biopsy reveals diffuse monocellular interstitial infiltration and epithelioid granulomas. In some cases, non-specific bone marrow and lymph node granulomas have been found. In the Tinu syndrome, the nephropathy is completely reversible, either spontaneously or following steroid treatment; this contrasts with the tendency towards relapse of the uveitis. The possible pathogenesis and the relationship with other idiopathic acute nephritis and uveitis are discussed. As in some previous publications, the presence of circulating immune complexes in our patient would suggest the involvement of the immune system. Temporary depression of cellular immunity was also observed in some cases. But the etiology and the pathogenesis of this syndrome are still unknown.

Acute Disease↗
PubMed1989

[Arthropathies following the administration of pefloxacin to an adolescent with mucoviscidosis].

We report the occurrence of knee joint effusion with prolonged functional impairment in a 17-year old boy with cystic fibrosis treated with pefloxacin for recurrent lower respiratory tract infections caused by Pseudomonas aeruginosa. Because the quinolone pefloxacin fairly often induces joint disease in pediatric age groups, we advocate restricting its use to those patients whose growth is completed. In growing individuals, it seems reasonable to use second generation quinolones only in infections caused by resistant organisms and to avoid exerting the joints during treatment.

Adolescent↗
PubMed1989

Structural and biochemical observations on specialized membranes of the "filter chamber", a water-shunting complex in sap-sucking homopteran insects.

Many homopteran insects feed on plant sap which contains solutes in very low concentration. Their digestive tract presents a complex called the "filter chamber" where the excess dietary water is believed to flow directly from the initial part of the midgut to the terminal part of the midgut and the proximal regions of the Malpighian tubules. Freeze-fracture experiments carried out on the filter chamber of Cicadella viridis revealed the presence of intramembrane particles on the whole surface of the microvilli and of basal membrane infoldings of the cells. Examination of negatively stained isolated membranes and of freeze-dried shadowed membranes revealed that the inner surface of the membrane is covered with particles protruding into the cytoplasm; they correspond to the numerous intramembrane particles observed on the P fracture face of the membrane. The outer surface of the membrane exhibits a regular network which corresponds to that observed on the E fracture face. SDS-PAGE analyses were performed on purified membranes of the filter chambers of C. viridis and Philaenus spumarius. In both cases 2 major components, 25 kDa and 75 kDa, were detected. These 2 components appear to be specific for the filter chambers since they were not found in membranes isolated from the other parts of the midgut. Thus, the membranes of these filter chambers, thought to be water-shunting complexes, possess structural and biochemical peculiarities which are probably related to water permeability.

Animals↗
PubMed1988

Enzymatic ester synthesis with continuous measurement of water activity.

Ester synthesis from aliphatic monoalcohols and organic acids was investigated by using a microbial lipase. The reaction medium only contained the substrates and the enzyme without addition of water or organic solvent. During the reaction, water was produced and the water activity (aw) increased. Batch reactors and continuous-flow reactors were used. In batch, the aw was 0.13 at the beginning of the reaction and increased to reach a plateau at 0.77, after which ester synthesis continued without modification of the aw. Different alcohols and acids were tried in solid-liquid reactors, and all cases synthesis occurred, leading to a significant increase in the water activity. For continuous-flow reactors, the use of silica beads retaining water inside the reactor where the enzymatic reaction took place resulted in some control of the enzymatic reaction by changing the aw.

Alcohols↗
PubMed1988

Combination of cisplatin, vindesine, and dacarbazine in advanced malignant melanoma. A Phase II Study of the EORTC Malignant Melanoma Cooperative Group.

A Phase II study combining cisplatin, vindesine, and dacarbazine was performed on patients with disseminated malignant melanoma by the European Organization for Research and Treatment of Cancer (EORTC) Malignant Melanoma Cooperative Group (MMCG). The treatment consisted of intravenous administrations of dacarbazine 450 mg/m2, vindesine 3 mg/m2, and cisplatin 50 mg/m2 on day 1 and 8 of each course. Courses were repeated every 4 weeks. Treatment was discontinued in case of progression after two courses, otherwise continued until progression or for a minimum of six courses. One hundred five patients entered the trial with 92 patients being evaluable. The response rate calculated after clearance by the Extramural Review Committee shows four complete and 18 partial responses, i.e., 24%, with a median remission duration of 23 weeks. Toxicity and subjective tolerance to this regimen were moderate, requiring 140 modifications of 642 administrations (22%). Main toxicities were nausea and vomiting (95%), leucopenia (70%), alopecia (56%), peripheral neuropathy (32%), and nephrotoxicity (17%). The discussion emphasizes some particular points of interest in the management of advanced malignant melanoma.

Actuarial Analysis↗
PubMed1988

Left ventricular response to submaximal and maximal exercise in asymptomatic aortic regurgitation.

In patients with chronic aortic regurgitation the quantitative changes in loading conditions and left ventricular performance from rest to submaximal exercise have not been related to the magnitude of change observed from rest to maximal exercise. Changes in end-diastolic volume index, as a measure of preload, and measures of contractile performance (ejection fraction and the systolic blood pressure/end-systolic volume index ratio) were assessed at rest, submaximal and maximal supine bicycle exercise using radionuclide angiography in 74 patients with chronic moderate to severe aortic regurgitation. With exercise, end-diastolic volume index decreased in a stepwise manner from 166 +/- 47 to 152 +/- 41 to 143 +/- 41 ml/m2 at rest, submaximal and maximal exercise, respectively. For the entire group, these changes were not associated with a significant change in ejection fraction but were associated with stepwise increases in systolic blood pressure to end-systolic volume index ratio. However, when patients were divided into 3 subgroups based on an increase (group I), minimal change (group II) or a decrease (group III) in ejection fraction from rest to maximal exercise, stepwise increases in systolic blood pressure to end-systolic volume index were again observed in groups I and II but not in group III. These changes were significantly greater in group I than in group II at submaximal and maximal exercise levels. Differences in ejection fraction response and end-diastolic and end-systolic volumes with exercise in the 3 groups were evident at the submaximal exercise level.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve Insufficiency↗