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Biomedical subjects

C Simon

Publications and source records attributed to C Simon.

At least 271 records · Page 15Linked to original sources
PubMed1985

[Has intrauterine surgery using ultrasound a future?].

Based on three cases of foetal abnormalities (hydrocephalus, prune-belly syndrome, and unilateral multicystic renal disease) diagnosed and treated by intrauterine sonographic control, the article describes the technique, evolution and outcome of these cases. Two patients (the hydrocephalus and the prune-belly syndrome) died after delivery, whereas the third one lives in normal conditions. The different diagnoses and prognoses of this new surgical procedure are discussed. We think that hydrocephaly and renal obstruction have a very bad prognosis when diagnosis and therapy are not performed an initiated at an early stage. Unilateral disease of Potter-Syndrome is associated with a very good prognosis irrespective of whether therapeutic intervention is effected or not. For this reason, the intervention should be considered according to the compressive action that the cystic renal disease can exercise on the other kidney or lung.

Adult↗
PubMed1985

[Latex and coagglutination test of serum and urine in childhood pneumonia].

41 children with pneumonia (proven by X-ray) and 271 children with upper respiratory tract infections were examined for bacterial antigens (Haemophilus influenzae type b and pneumococci) in serum and urine. In patients with pneumonia blood cultures, deep nasal swabs and antibody assay in serum (against Mycoplasma pneumoniae and Chlamydia) were made. In 271 patients with an upper respiratory tract infection also a deep nasal swab for bacterial cultures was performed. In 29 of 41 patients with pneumonia latex agglutination test was positive (in 15 patients for Haemophilus antigen, in 14 patients for pneumococcal antigen). Coagglutination test was positive in 6 patients (in 1 patient for Haemophilus antigen, in 5 patients for pneumococcal antigen). In 12 patients latex agglutination was negative; there were other causes of pneumonia (partially viral infections). In 5 of 271 patients with an upper respiratory tract infection (purulent otitis media) latex agglutination was positive (4 times for Haemophilus, once for pneumococcal antigen). Bacteriological investigations confirmed the results of latex agglutination test in serum and urine. To avoid false positive reactions we recommend heating of serum to 65 degrees C, of urine to 100 degrees C for 5 min. Urine should be concentrated 25 times (there were 3 times more positive results than with unconcentrated urine).

Adolescent↗
PubMed1984

Nucleoside diphosphate kinase from brain. Purification and effect on microtubule assembly in vitro.

Tubulin strictly requires GTP for its polymerization. Nevertheless, microtubule assembly can be observed in the presence of ATP as the only nucleotide triphosphate, due to the nucleoside diphosphate kinase (NDP kinase) present in microtubule preparations, and which phosphorylates the GDP into GTP. We have purified this enzyme from pig brain to homogeneity, and shown that its relative mass is close to 100 000 in its native state, and 17 000 under denaturing conditions. Therefore it is probably a hexamer, as previously shown for the enzyme from other sources, and also presents a microheterogeneity, with the major isoforms between pI 5.0 and 6.0. The enzyme is transiently phosphorylated during catalysis, as expected within a ping-pong bi-bi mechanism. The effect of the NDP kinase on pure tubulin polymerization was studied: in the presence of NDP kinase, the lag time observed in the kinetics of microtubule assembly was shorter and the final extent of assembly was unchanged. The effect of the enzyme was observed at enzyme concentrations 900-fold lower than tubulin concentration, which shows that the NDP kinase acts catalytically. Kinetic data show that the catalytic effect of the NDP kinase is faster than the rate of nucleotide exchange on tubulin under the same conditions. This result demonstrates that the tubulin-GDP complex itself is a substrate for the enzyme, which may indicate that the GDP bound to tubulin at the E site is exposed on the surface of dimeric tubulin.

Animals↗
PubMed1984

Polymorphism of tubulin oligomers in the presence of microtubule-associated proteins. Implications in microtubule assembly.

The interaction between tubulin and microtubule-associated proteins (MAPs) in solutions of cycled microtubule protein has been studied by using radioactively labeled MAPs. Kinetic data of MAP association to microtubules in the polymerization process indicate that an oligomer P of tubulin and MAPs is the polymerizing species. Analysis of MAP binding to microtubules formed from solutions in which the ratio MAPs/tubulin was varied shows evidence for a polymorphism of tubulin-MAP oligomers. When the ratio MAPs/tubulin is decreased by addition of dimeric tubulin to 3 times cycled microtubule protein, an oligomer P' less rich in MAPs than P and unable to incorporate in microtubules is formed. The data further show that while tau, MAP1, and MAP2 can bind to oligomer P, only MAP1 and MAP2 can bind to oligomer P'. Therefore, the interactions of tau factor and of MAP1 and MAP2 with tubulin follow different patterns.

Animals↗
PubMed1984

Interaction between microtubule-associated protein tau and spectrin.

Tau factor, one of the microtubule-associated proteins (MAPs), is shown here to bind to spectrin. Evidence for an interaction between these two proteins is provided by spectrin affinity chromatography of brain MAPs, gel overlay of electrophoresed MAPs with 125I-labelled spectrin, incorporation of tau factor in human erythrocyte ghosts, and demonstration that tau inhibits the F-actin cross-linking activity of tetrameric spectrin. The wide distribution of both tau and spectrin-like proteins in eukaryotic cells is in favor of the possible biological significance of this interaction. The results suggest that tau could be one of the proteins involved in the concerted regulation of microtubule and actin networks in the membrane vicinity.

Actins↗
PubMed1984

ATP-induced stimulation of the intralysosomal hydrolysis of thyroglobulin. Evidence for an ATP-driven proton pump in thyroid lysosomes.

It is commonly admitted that the intralysosomal hydrolysis of thyroglobulin, which promotes thyroid hormonal secretion, requires an acidic pH. As a consequence the mechanisms by which such an acidic pH is set-up and maintained present an acute physiological interest. In the present work the extent of the intralysosomal hydrolysis of thyroglobulin (amount of TCA-soluble radioiodine formed during incubations of isolated thyroid lysosomes) has been retained as an index for the intralysosomal pH. Incubations in highly concentrated (250 mM) alkaline buffer, preincubations at 0 degree C in the presence of alkaline buffers or of methylamine, and incubations in the presence of FCCP (protonophore which dissipates proton-gradients) induced alkalinization of the lysosomal matrix (significant inhibition of thyroglobulin degradation). Addition of ATP to the incubation medium was shown to prevent these alkalinizations and to re-establish the acidic intralysosomal pH (normal thyroglobulin degradation) every time it had been experimentally increased. These results argue in favour of the existence of an ATP-driven proton pump in the membranes of thyroid lysosomes.

Adenosine Triphosphate↗
PubMed1984

Loss of suppressor T-cells in active inflammatory bowel disease.

The proportions and absolute numbers of helper and suppressor T-cells in 40 patients with inflammatory bowel disease and 22 control subjects were determined, using the monoclonal antibodies OKT 4 and OKT 8. There were no significant differences in helper or suppressor cell proportions among 15 steroid treated patients with active inflammatory bowel disease, 10 patients with inactive inflammatory bowel disease, 10 patients with other gastrointestinal diseases, or 12 normal control subjects. In contrast, 15 patients with active inflammatory bowel disease not treated with corticosteroids manifested increased proportions of helper cells and decreased proportions of suppressor cells (p less than 0.001), compared with all other patient groups and to normal controls. When absolute numbers of helper and suppressor subsets were measured, these alterations in proportions of helper and suppressor cells were primarily attributable to decreased counts of suppressor T-cells both in patients with active Crohn's disease and in those with ulcerative colitis (p less than 0.01). In four patients undergoing serial study, the helper/suppressor ratios appeared to rise and fall respectively with clinical exacerbations and remissions of disease. These data provide additional evidence for the involvement of cellular immune systems in these disease processes.

Adolescent↗
PubMed1984

[An optimal blood culture technic].

For blood cultures in septicemic patients it is advisable to use two broth culture bottles. One bottle should be incubated with air, the other without (for anaerobes). Supplemented Peptone Broth II (Becton-Dickinson) and BHI Roche were superior for culturing aerobic and anaerob bacteria in comparison to other blood culture media. They are commercially available, and with these media it is not necessary to inoculate two bottles with blood from one patient. Supplemented Peptone Broth II is also suitable very well for the isolation of Campylobacter fetus and has a redoxpotential which is especially favourable for the isolation of anaerobes.

Bacteria, Aerobic↗
PubMed1984

[Air pathogen content in the intensive care station of a pediatric clinic].

The bacterial count of air in 2 intensive care units was examined by membrane filter technique (MD 2 model SM 167 21). 88 samples of room air and 296 samples of incubator air were studied. The occurrence of bacteria, especially gramnegative rods, was investigated in incubators and in respirators. The results were related to bacterial counts in tracheal secretions from newborns during long term ventilation. The bacterial content of air in the incubators were relatively low. The results were different in two intensive care units leading to changes in the hygienic routine of intensive care units.

Air Microbiology↗