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Biomedical subjects

M Geindre

Publications and source records attributed to M Geindre.

At least 19 recordsLinked to original sources
PubMed1993

Characterization of reactions catalysed by yeast phosphatidylinositol synthase.

The nature of reactions catalysed by yeast phosphatidylinositol synthase expressed in E. coli has been investigated. The single enzyme is shown to carry both CDP-diacylglycerol-dependent incorporation of inositol into phosphatidylinositol (Km for inositol of 0.090 mM) and a CDP-diacylglycerol-independent exchange reaction between phosphatidylinositol and inositol (Km for inositol of 0.066 mM). The exchange reaction and reversal of phosphatidylinositol synthase were both stimulated by CMP, but had different optimum pH and requirements for substrates. These results suggest that CMP-stimulated exchange and CMP-dependent reverse reactions are distinct processes catalysed by the same enzyme, phosphatidylinositol synthase.

CDP-Diacylglycerol-Inositol 3-Phosphatidyltransfer↗
PubMed1993

Active transport of L-proline in the protozoan parasite Trypanosoma brucei brucei.

The characteristics of L-proline transport in the procyclic form of Trypanosoma brucei were studied by using L-[14C]proline and a quick separation technique by centrifugation through an oil mixture. L-Proline uptake displayed typical Michaelis-Menten kinetics, with a Km of 19 microM and a maximum transport velocity of 17 nmol/min per 10(8) cells at 27 degrees C. The maximum concentration gradient factor obtained after 1 min of incubation was 270-fold in 0.02 mM proline. Cells permeabilized with 80 microM digitonin were still able to accumulate 14C label, but to a lower extent. The temperature-dependence of proline uptake gave an apparent activation energy of 74.9 kJ.mol-1. In competition studies with a 10-fold excess of structural analogues, L-alanine, L-cysteine and L-azetidine-2-carboxylate were found to inhibit L-proline uptake. Variation of pH or addition of the protonophore carbonyl cyanide m-chlorophenylhydrazone ('CCCP') did not affect proline transport, showing that it is not driven by a protonmotive force. The absence of Na+, with or without monensin, did not affect proline transport. The absence of K+ and the addition of the Na+,K(+)-ATPase inhibitor ouabain had no significant effect on proline uptake activity. The thiol-modifying reagent iodoacetate (10 mM) decreased proline uptake by half. KCN (1 mM) inhibited proline uptake to a lesser extent, and the degree of inhibition was proportional to the intracellular ATP concentration. Preliminary experiments on proline transport in plasma-membrane vesicles of the cells, using a filtration technique, showed an uptake of proline (0.67 nmol/mg of protein) by the vesicles, but only in the presence of intravesicular ATP. The results thus obtained suggest that the proline carrier system in T. brucei is ATP-driven and independent of Na+, K+ or H+ co-transport.

Adenosine Triphosphate↗
PubMed1982

[The new radiology].

After a brief analysis of the relations existing between the disciplines of Radiology, Biophysics, and Clinical Medicine, and, the political and administrative sectors, certain themes are developed concerning general problems related to modern radiology: its true place in Medicine today, its evolution, and its organization as a function of current technological advances. Among the questions discussed are the training of new radiologists, the development of complex technical equipment and thus the mode of practice of radiology, the organization of hospital teams and the recruitment of staff adapted to perform tasks of increasing diversity, and the future of research in this field.

Humans↗
PubMed1982

[Cytologic grade, a prognostic factor in breast cancer].

Fine needle aspirations of breast carcinomas, submitted to a hypochromic Papanicolaou staining procedure, provides useful prognostic data. Three grades of increasing severity were used as a classification. An homogeneous group of 189 patients submitted to similar therapeutic management has been analyzed: 15.3/1 000 patients/months of those classified in grade III, versus 5.2 in grade II and 2 in grade I have had a worsening outcome within 1 to 5 years. The correlation of the cytoprognostic classification with TNM classification and lymph node involvement is significant. Moreover grade III points at patients with high metastatic potential: 27 per cent of stage I, 18 per cent without lymph nodes involvement and 23 per cent with less than 3 lymph nodes involved will develop recurrence within 5 years. The absence of steroid receptors confirms the poor prognosis of grade III.

Biopsy, Needle↗
PubMed1982

[The value of tomodensitometry in the diagnosis of dermoid cysts. Apropos of 5 cases].

Results of computed tomography before operation in 5 cases of dermoid cysts (mediastinal: 3; retroperitoneal: 1; ovarian: 1) are employed to assess the contribution of this technique, and to define its place in relation to other diagnostic radiological procedures (straight radiographs and ultrasonography). The CT scan enables three morphological types to be distinguished, and also supplies very precise data on the extension, limits, and relationships of the tumor. The effective place of this examination in the diagnosis of dermoid cysts depends upon two factors: data obtained from the straight radiograph and the initial site of the lesion. When the former supplies specific information, the only role of the CT scan and ultrasonography is to determine the precise extent of the tumor pre-operatively, the CT scan being superior to ultrasonography for this purpose. When straight radiographs do not reveal characteristic signs, the diagnostic assistance of the scanner appears to be irreplaceable, even in those abdominal or pelvic regions where ultrasonography is best conducted.

Adult↗
PubMed1981

[Diagnostic radiology in mediastinal disorders : technical progress and current strategy (author's transl)].

After a brief reminder of recent progress in radiological methods in the diagnosis of mediastinal disorders, the authors study the contribution of Computerised Axial Tomography (T.D.M.). The advantages of T.D.M. in mediastinal disease rest on two characteristics : the morphological study of the mediastinum is made easier by the display of transverse axial cuts with nothing superimposed; the density measurements can distinguish between opacities which would appear similar on conventional radiology. Three facts have been established by the authors : T.D.M. raises the diagnostic sensitivity of radiology; in distinguishing between fatty, watery, vascular and solid tumours, it increases aetiological specificity; it simplifies the diagnostic approach while increasing the efficiency of radiology and the importance of its role in therapeutic decisions. In a typical case where one has just discovered an abnormal mediastinal opacity (and in whom a gastro-intestinal primary has been excluded), T.D.M. should be the first examination after standard radiography, because its results determine the remaining investigation. T.D.M. is specially indicated in evaluating a myasthenic or when investigating an anomaly in the infero-posterior mediastinum. A few cases do not entirely fit in to this schema, because of a particular clinical or radiological situation such as : mediastinal adenopathy; the assessement of the extent of a bronchogenic carcinoma; anterior cardio-phrenic opacities. The examination of the hila again has its limits when the abnormal opacity is small as there are errors in the technique due to the effects of incomplete volume. Finally, there remains the improved cost-effectiveness of the radiological examination of the mediastinum with the rational use of T.D.M.

Aortic Aneurysm↗
PubMed1981

[Oesophageal cancer extension. Diagnostic contribution and effects on therapy of computed tomography. Report on 40 cases (author's transl)].

Based on a homogeneous series of 40 cases of thoracic or abdominal oesophageal cancer, of which 23 had been confirmed by operation, the authors analyse the contribution of the CT scan to the diagnosis of the extension of the cancer, and evaluate the effects on therapy of this technique. Computed tomography supplies much more precise and complete details of possible cancer extension than any other pre-operative investigation. Conducted after radiological and endoscopic examination of the oesophagus, it supplies rapid, perfectly readable, irreplaceable information on local, regional, and metastatic spread of the cancer. This only slightly aggressive examination enables evaluation of the size of the tumour and its direct relationships, effective exploration of the mediastinal and coeliac glands regions, and detection of possible pleural, pulmonary, or hepatic metastases. Its role in the decision to operate is a considerable one: true assessment of of local, regional, or metastatic extension assists the surgeon in his choice of either curative or palliative therapy. Better still, it enables a route of approach to be decided as a function of data concerning possible extension, as well as the best surgical tactic. As a support for radiotherapy or chemotherapy for this type of cancer, computed tomography greatly assists follow-up supervision.

Esophageal Neoplasms↗