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Biomedical subjects

J Simon

Publications and source records attributed to J Simon.

At least 649 records · Page 36Linked to original sources
PubMed1976

Role of the pneumo-encephalogram in the diagnosis of spontaneous subarachnoid haemorrhage.

The authors have collected eighteen cases of primary intraventricular lesions revealed by a subarachnoid haemorrhage. Among these cases, the most important are the choroid plexus papillomas followed by ependymomas; some cases have no precise histological interpretation. Generally speaking, cerebral arteriography gives only indirect evidence of ventricular dilation and thus does not confirm the presence of a lesion. On the contrary, the pneumoencephalogram is consistantly positive, but does not give the differential diagnosis between intraventricular tumours and primary intraventricular haemorrhages. This test should therefore be given the same importance as spinal cord arteriography in the exploration of subarachnoid haemorrhages with negative cerebral angiograms.

Adolescent↗
PubMed1976

Leukocyte-platelet interaction. Release of hydrogen peroxide by granulocytes as a modulator of platelet reactions.

Because of the many potent biological capabilities of the blood granulocytes, and their contact with platelets in various physiologic and pathologic states, a possible interaction between granulocytes and platelets was investigated. Platelets were purified by gel filtration and via a dialysis membrane were separated from suspensions of autologous granulocytes prepared by dextran sedimentation and resuspended in modified Tyrode's buffer. After 20 min at 37 degrees C platelet aggregation was shown to be diminished by such exposure, as compared to the aggregation of platelets incubated with dialysates of buffer only. When granulocytes were stimulated by the addition of 1.1-muM latex spheres as target particles for phagocytes, the dialysate of these cells exhibited greatly enhanced platelet-inhibitory properties. The addition of catalase to the platelets abolished the effect of exposing these cells to the dialysate of resting granulocytes and markedly inhibited the effect of exposing the platelets to the dialysate of phagocytosing granulocytes. Catalase treated with 3-amino-1,2,4-triazole had no platelet-protective capacity. Purified suspensions of lymphocytes released no platelet-inhibitory principle under these experimental conditions. Hydrogen peroxide in the dialysate of granulocytes was measured directly with an assay involving an H2O2-induced decrease in the fluorescence of scopoletin catalyzed by horseradish peroxidase. The dialysate of phagocytosing granulocytes contained 0.86 +/- 0.55 nmol H2O2/2.5 X 10(7) granulocytes when sampled at 20 min. By an alternate measurement technique in which scopoletin and horseradish peroxidase were present in the dialysate from time zero, the mean amount of H2O2 in the dialysate reached 4.0 +/- 1.3 nmol/2.5 x 10(7) granulocytes at 20 min. This discrepancy suggested the consumption of H2O2, possibly mediated by the granulocytes themselves. This possibility was investigated by the addition of exogenous H2O2 to the test system. Both granulocytes and platelets enhanced the disappearance of H2O2 from the dialysate, and the amount consumed was proportional to the amount of H2O2 added to the system. Glucose oxidase at 12 M U/ml plus glucose in excess resulted in the production of H2O2 at a rate and final amount comparable to that produced by phagocytosing granulocytes. This mixture, when substituted for phagocytosing granulocytes in the standard dialysis membrane experiment, induced an inhibition of platelet aggregation similar to that caused by the granulocytes. The observation that the release of H2O2 by the blood granulocyte influences platelet function suggests a potential role for the granulocyte in the regulation of hemostasis or thrombosis.

Adenosine Diphosphate↗
PubMed1976

Orbital phlebography and cavernography in intra-cranial lesions.

Orbital phlebography has gained increasing importance in the evaluation of otologic and intracranial pathology. The practical use of this method in vascular and neoplastic lesions in the middle cranial fossa, as well as its probable value in cerebello-pontine angle tumours is reported.

Adult↗
PubMed1976

Effects of age and cold on pulmonary bacterial clearance in the young pig.

Young pigs (1, 6, 18, or 26 days of age) were exposed to an aerosol of a nonpathogenic strain of Escherichia coli and then held for a 3-hour clearance period in either a thermoneutral (32 C environmental temperature at 1 or 6 days of age, 24 C at 18 or 26 days of age) or a cold (6 C) environment. Pigs were then killed and pulmonary bacterial clearance was determined. There appeared to be an age dependent improvement in the capability of the pig to clear its lungs of the bacterial load. Cold appeared to inhibit pulmonary bacterial clearance, but this inhibitory effect became progressively less as the pigs became older. In a supplementary experiment conducted to assess the effect of age-within-litter (2 and 14 days of age) on pulmonary bacterial clearance, it was confirmed that young pigs were less able to clear nonpathogenic E coli from the lungs.

Age Factors↗
PubMed1976

[Parenteral nutrition in infancy (author's transl)].

The indication for, and complications of, parenteral alimentation are reviewed. Many of the problems regarding the proper composition of an alimentation mixture suitable for infants still remain unsolved. Various intravenous routes are described. Total parenteral nutrition requires considerable technical equipment, an expert team and a meticulous technique. Each case presents a fresh problem.

Edema↗
PubMed1975

Simian virus 40-related antigens in three human meningiomas with defined chromosome loss.

Two out of seven meningiomas tested in early cell cultures by indirect immunofluorescence staining showed simian virus 40 (SV40)-related tumor (T) antigen. In one tumor 90% of the cells were positive. An additional SV40-related antigen (U) was found in 10% of cells of a third tumor. These findings indicate that the meningioma cells showing a positive reaction are transformed by a papova virus that has at least partly the same antigenic properties as SV40 virus. SV40-related viral capsid (V) antigen was absent in all the meningiomas tested. No virus infectious for African green monkey kidney (AGMK) cells could be isolated. The tumors positive for T and U antigens showed the chromosome aberration typical for human meningiomas, i.e., the loss of one chromosome, G-22. The T-antigen-positive tumors showed further hypodiploidization. Experiments to rescue virus from the T-antigen-positive tumors showed further hypodiploidization. Experiments to rescue virus from the T-antigen-positive meningioma cells were performed: fusion of cells pretreated with 8-azaguanine with cells premissive for SV40 led to a low percentage (0.01-0.05%) of V-antigen-positive nuclei in heterokaryon cultures. On the basis of these results, the possibility of a correlation between the meningioma, a relatively common intracranial tumor in man, and an SV40-related papova virus must be considered. It remains to be shown whether this virus is a causative agent for human meningiomas.

Adult↗
PubMed1975

The etiology of swine dysentery. III. The role of selected gram-negative obligate anaerobes.

A disease resembling swinee dysentery occurred in gnotobiotic piglets previously colonized with Escherichia coli and given a mixture of five enteric anaerobes and spirochete B-78, orally. No disease occurred in germ-free piglets exposed to four Gram-negative obligate anaerobes or to the spirochete; however, if the four respective anaerobes were introduced into gnotobiotic pigs previously colonized with the spirochete, or when the spirochete was introduced into gnotobiotic pigs colonized with the anaerobes, a disease occurred that simulated swin dysentery. Swine dysentery is probably caused by the specific interaction of one or more enteric Gram-negative obligate anaerobes and a spirochete.

Animals↗