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Biomedical subjects

D Thomas

Publications and source records attributed to D Thomas.

At least 811 records · Page 45Linked to original sources
PubMed1985

Intrathecal morphine in cardiac surgery.

The effects of intrathecal morphine in 60 patients undergoing open-heart surgery were studied in an observer-blind control trial. The patients were randomly allocated into three groups of 20 each: (A) Control, (B) 2 mg and (C) 4 mg of intrathecal morphine. This study confirms that intrathecal morphine provides useful post-operative analgesia. Patients given intrathecal morphine required less postoperative analgesia and sedation and their respiratory function tests were less depressed than the control group. Since the completion of this study, reports have suggested that 1 mg of morphine intrathecally avoids the serious complications of respiratory depression. In the study described, the patients were electively ventilated post-operatively and respiratory depression was therefore not a problem. Of the other associated side-effects of intrathecal morphine, vomiting (20%) and pruritus (20%) proved the most troublesome.

Adolescent↗
PubMed1985

Phase II study of cisplatin in advanced osteogenic sarcoma. European Organization for Research on Treatment of Cancer Soft Tissue and Bone Sarcoma Group.

The activity of cisplatin (CDDP) against advanced osteogenic sarcoma was evaluated in 37 of 50 patients registered by the members of the European Organization for Research on Treatment of Cancer Soft Tissue and Bone Sarcoma Group between 1979 and 1982. All patients had measurable lung metastases. Thirty-one patients (84%) had received previous chemotherapy consisting mainly of high-dose methotrexate, doxorubicin, and vincristine. CDDP (100 mg/m2) was given as a 24-hour continuous infusion every 3 weeks for a minimum of two cycles, with appropriate fluids and diuretics. In the absence of impairment of the renal function and/or myelosuppression, the dose could be escalated by 20%. The overall response rate was 19% (seven responses among 37 patients), with one complete remission for 51 weeks and six partial remissions from 12 to 26 weeks. The median number of courses of CDDP administered was three, ranging from two to 11. Of 143 courses administered, only 18 (12%) had to be modified because of toxicity. In 16% of the patients some transient impairment of the renal function was observed. CDDP adds to the limited number of chemotherapeutic agents with useful properties in osteogenic sarcoma, and CDDP-containing combination chemotherapy regimens should be actively investigated.

Adolescent↗
PubMed1985

[Carcinoembryonic antigen in intestinal lavage fluids and the tissue of colorectal tumors].

Determination of carcinoembryonic antigen (CEA) was carried out in 48 intestinal washing fluids (21 from healthy subjects, 15 from patients with polyps and 12 from patients with colorectal carcinoma). The histologic study of polyps and the histologic and immunohistochemical studies of tumors were realized. In the polyps's group, the mean of ACE is significantly higher than that of the volunteers's group, but 7 subjects have a CEA level below the mean and 8 subjects have a CEA level twice this mean. Furthermore, the CEA level seemed to be independent of histologic grade of polyps. The mean of CEA levels in the subjects with colorectal carcinoma is significantly higher than that of volunteers, but 4 of 12 patients have a CEA level below the mean of healthy subjects. The CEA levels are very variable for an identical stage of tumor's differentiation and is independent of Dukes stage (B-C or D). CEA determination in intestinal washing fluids allows neither the detection nor the appreciation of intestinal carcinoma's extend.

Adult↗
PubMed1985

[Biosensor development in clinical analysis].

The use of enzymes immobilized or as markers formed the subject of more than thousand publications in the field of industry or biomedical applications, during the last five years. Recently, some authors published works concerning immobilization of total microorganisms for catalytic purposes, others use the enzymatic activity for marking molecules involved in immunological analysis processes. Together industrial biotechnology and medical analysis laboratory are interested with the evolution of these procedures involving the activity of immobilized enzymes. Enzyme immobilization allowed the lowering of analysis costs for, in this case, the enzyme can be used several times. We take account of the two main cases which are encountered during utilization of immobilized enzymes of analytical purposes. The enzyme is used directly for the catalysed reaction or it is used as enzymatic marker. These both aspects are developed mainly for the elaboration of enzymatic and immunoenzymatic electrodes and the realization of automatic computerized devices allowing continuous estimation of numerous biological blood parameters. From these two precise examples, glucose and antigen determination, the authors show the evolution of these technologies in the field of immobilized enzymes or captors and the analysis of signals given by these electrodes requiring a computerized treatment. This new technology opens to important potentialities in the analytical field. The automatization of these devices allowing the control in real time, will probably make easier the optimization steps of procedures actually used in the biomedical sphere.

Acetylcholine↗
PubMed1985

[Cor triatriatum of adults. Apropos of 2 new surgically treated cases in adults].

The authors report two cases of cor triatriatum in a 54 year old woman undergoing open heart surgery with a preoperative diagnosis of mitral stenosis, and a 24 year old woman in whom the diagnosis had been made before surgery. Resection of the abnormal intra-left atrial fibrous membrane successfully restored normal haemodynamics in both cases. The main clinical and diagnostic features of the condition are described.

Adult↗
PubMed1985

[Familial forms of interauricular communication of the ostium secundum type].

The occurrence of several cases of ASD in the same family is rare. Familial forms of ASD are characterised by the high incidence of associated cardiac lesions in affected patients or in the family, by the frequency of atrioventricular block with prolongation of the PR interval and by the presence of a large defect in the interatrial septum. The condition is thought to be transmitted in an autosomal dominant manner. The authors report the case of a family in which 7 cases of ASD were found, 6 of which were repaired surgically. There were no associated cardiac or extracardiac malformations; AV conduction was normal in 4 of the 6 operated cases--the defects were all large. The study of the genealogical tree with examination of most members of the family suggests autosomal dominant transmission of the condition.

Adolescent↗
PubMed1985

[Radiologic imaging of annulo-ectasia disease of the aorta. Experience with 26 cases].

The authors describe the radiologic appearance of annulo-aortic ectasia in 26 patients who had plain chest radiography and aorto-seriography. Two also underwent C.T. Aortography is the most performing method to appreciate the extent of aortic ectasia, the perturbations of the aortic root and to diagnose acute or chronic dissections. Aortography remains a most valuable complement of echocardiography for preoperative staging.

Adult↗
PubMed1985

Mathematical modeling of immobilized enzyme systems.

We model the interaction of reaction and diffusion in immobilized enzyme systems by P.D.E.s or simpler equations. We present models with only one steady state, others with multiple steady states (in particular one related to morphogenesis) and some with periodic solutions. The usefulness of continuation methods to resolve this complexity of behaviors is pointed out.

Enzymes, Immobilized↗
PubMed1984

Red cell-labelled monoclonal antibodies for assay of human chorionic gonadotropin and luteinising hormone by reverse passive haemagglutination.

The assay of human chorionic gonadotropin and luteinising hormone by reverse passive haemagglutination reaction, using monoclonal antibodies coupled to red cells, is described. Quantitation is achieved by end-point determination for serial dilutions of standard or sample, the haemagglutination reaction being observed after settling under gravity for 90 min. Red cell-labelled antibodies were stabilised with glutaraldehyde without loss of sensitivity and allowing long term storage. Various antibody combinations were assessed, and the best combination under optimum conditions gave a positive haemagglutination reaction down to 0.2 ng/ml with HCG.

Antibodies, Monoclonal↗
PubMed1984

Reactivation of the hydrogenase from Desulfovibrio gigas by hydrogen. Influence of redox potential.

The specific activity of the periplasmic hydrogenase from Desulfovibrio gigas is increased approximately 10-fold in the H2 utilization assay with benzyl viologen by several hours of incubation under an atmosphere of H2. After a variable lag phase during which residual traces of O2 are removed, the reversible activation is exponential. The extent of activation is dependent on pH and the redox potential of the incubation medium. A tentative model based on the existence of a monoelectronic redox center is proposed as shown in the following equation: (formula; see text) The potential of this redox couple was determined to be -310 mV (pH = 7; T = 298 K) versus the normal hydrogen electrode.

Desulfovibrio↗
PubMed1984

The effects of oxygen solubility and high concentrations of salts on photosynthetic electron transport in chloroplast membranes.

Chloroplast membranes were isolated in different media containing Hepes [4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid] and high concentrations of sorbitol (0.33 M), potassium citrate (0.75 M) or Na2SO4 (1.0 M). Due to the complexity of the media, the oxygen solubility is strongly modified by high concentrations of salts (oxygen solubility for 0.33 M-sorbitol, 0.21 mmol/litre; for 0.75 M-potassium citrate, 0.121 mmol/litre; and for 1.0 M-Na2SO4, 0.112 mmol/litre). The knowledge of these values is necessary to interpret the rate of O2 evolution. For thylakoids isolated in 'sorbitol buffer' and then tested in high concentrations of potassium citrate, a slight stimulation of O2 evolution is observed (143-173 mumol of O2/h per mg of chlorophyll a) with potassium ferricyanide as electron acceptor. When we monitor the potassium ferricyanide reduction, no stimulation of electron transport is obtained even if the observed phenomenon is identical with the Photosystem-II oxygen evolution. In the same experiments no stimulation of the photophosphorylation was recorded, but when thylakoids are directly isolated in 0.75 M-potassium citrate, O2 evolution, ferricyanide reduction and photophosphorylation are inhibited by high concentrations of salts. The behaviour of thylakoids seems to be influenced by their initial treatment.

Cell Membrane↗
PubMed1984

A computerised enzyme immunosensor: application for the determination of antigens.

The present report gives preliminary results of a new sensitive method for the amperometric determination of antigens in serum. This method, developed from the biological model 'hepatitis B surface antigen antibodies' is less time-consuming than most immunochemical techniques, and eliminates many inconveniences arising from use of isotopes. Specific antibodies immobilised onto a gelatin membrane are applied in a solid phase 'sandwich' procedure. The antibodies are labelled with glucose oxidase. The measurement consists of an immunological process and an enzymatic reaction. The second part is carried out by fixing the active membrane onto a pO2 electrode. The sensor is immersed in a standard glucose solution and a signal is obtained by measuring the consumption of oxygen due to the enzyme reaction. This response is correlated to the antigen concentration of the sample. It is a function of both the diffusional and the reactional characteristics of the active layer. Under software conditions, the signal is sampled when the stationary state is obtained. The difference between initial signal and the stationary state signal is measured and compared with the pre-set calibration curve. Use of the computerised enzyme immunosensor could easily be extended to assay of other antigens and haptens that are usually determined by radioimmunoassay.

Antibody Formation↗