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Biomedical subjects

M Samson

Publications and source records attributed to M Samson.

At least 73 records · Page 4Linked to original sources
PubMed1989

[Causes of first convulsive seizures in adults. According to age and sex].

In the absence of epidemiological studies, we thought it might be of interest to investigate the relative frequency of first seizures in adults according to age and sex and in comparison with a control population. Our study of 317 patients admitted to hospital a few hours at most after the seizures demonstrated that alcoholism in young adults and vascular pathology in the elderly play an important role in triggering the first seizures, which accounts for the male predominance in epilepsy of the adult. It also showed that the occurrence of first seizures increases with age, especially after 60 years. We found that premonitory symptoms were present in almost one-third of the patients, even when the seizures seemed to be generalized from the start, and that there was a risk of one or several attacks during the hours that followed the first seizures.

Adult↗
PubMed1989

Binding of antigen to Ia molecules on intact antigen presenting cells demonstrated by photoaffinity labeling.

We used a photoaffinity labeling technique to investigate whether a molecular interaction occurs between antigen and Ia molecules on antigen presenting cells (APC) in the absence of T lymphocytes. M.12.4.1 B lymphoma cells (Iad), which are able to present bovine insulin to Iad lymph node primed T cells, were given radioiodinated bovine insulin derivatized with the photoreactive group (2-nitro-4-azidophenylacetyl) at Lys 29 of the B chain of the insulin molecule. Processing of insulin was allowed by incubating the APC with antigen for increasing periods of time at 37 degrees C or 4 degrees C. The covalent coupling of the processed photoreactive antigen to any neighboring cellular protein was thereafter induced by u.v. irradiation. Immunoprecipitation of membrane proteins by monoclonal antibodies showed that under these conditions, the alpha and beta subunits of the Ia molecules were selectively photolabeled. Labeling was time- and temp-dependent as was the internalization of insulin. The apparent mol. wts of the antigen-Ia molecule complexes were not significantly different from that of native Ia molecules radioiodinated by surface labeling, indicating that only a small fragment of the antigen was covalently coupled to Ia molecules. Similar experiments performed with human B lymphoma cells (526 cells) gave similar results. These observations therefore indicate: (1) that Ia molecules expressed by intact APC are able to bind antigens in the absence of T lymphocyte antigen receptor; and (2) that this association, at least for insulin, requires uptake and a proteolytic fragmentation of the antigen by the APC.

Affinity Labels↗
PubMed1989

[Implantation of endoprostheses in aortocoronary bypass. Preliminary experience at the Thoraxcenter of Rotterdam].

An intraluminal stent was implanted in 5 patients after dilatation of an aorto-coronary venous graft. In the first 4 patients the procedure was motivated by restenosis after angioplasty. In the 5th patient the stent was implanted as a first-line measure in a case of dilated venous bypass stenosis. Stent implantation carries a risk of thrombosis and requires effective anticoagulation. Thus, one of our patients had to be reoperated upon for prosthetic thrombosis facilitated by the withdrawal of anticoagulants owing to a gastrointestinal haemorrhage. After a 3-month follow-up, the results seem to be encouraging in spite of a case of restenosis located at the proximal end of the tutor. However, more time will be needed to determine precisely the effectiveness of stents in the prevention of restenosis after venous graft dilatation.

Aged↗
PubMed1988

A new approach for the evaluation of recovery after peripheral nerve damage.

The major caudal nerves of the rat provide an excellent model for longitudinal evaluation of nerve repair following a crush lesion. The surgical procedure and the method for testing sensory recovery are described in detail. Using this technique a clear, positive effect of ORG.2766 (an ACTH (4-9) analog) on the regeneration of sensory nerves could be shown. Results support the suggestion that ORG.2766 enhances the initial sprouting response, rather than exerting an effect on the growth rate of newly developed sprouts.

Adrenocorticotropic Hormone↗
PubMed1988

Topographical expression of class I major histocompatibility complex antigens on human amniotic epithelium.

The expression of class I major histocompatibility complex (MHC) antigens on different regions of human amnion was studied by the avidin-biotin-complex immunoperoxidase (ABC) technique using monoclonal antibodies. In contrast to previous reports, the use of higher affinity monoclonal antibodies and the sensitive immunoperoxidase method has allowed the identification of class I MHC antigens on the amniotic epithelium. The level of expression is different between cells from various parts of the amnion, with the amniotic epithelium from the edge of the placenta consistently showing the strongest reactivity. Some of the class I MHC antigens expressed by the amnion are similar to those expressed by extravillous trophoblast cells in that both show much weaker or no reactivity with the monoclonal antibody 61D2.

Amnion↗
PubMed1988

Monoclonal antibody GB24 recognizes a trophoblast-lymphocyte cross-reactive antigen.

GB24 is a mouse monoclonal antibody (IgG1) raised against human term placental microvilli. This antibody displayed pan-trophoblast reactivity pattern. In addition, GB24 recognized normal peripheral leukocytes and transformed cell lines (Daudi, HL-60, Jurkat, AV3, BeWo, HT-29) by using membrane immunofluorescence and flow cytometry. By SDS-polyacrylamide gel electrophoresis, this antibody immunoprecipitated two proteins of 62 kilodaltons (kDa) and 75 kDa from placental microvilli. Isoelectrofocusing analysis revealed that these two bands exhibited different isoelectric points: 4.7 for the 62 kDa protein, 4.6 and 4.4 for the two spots corresponding to the 75 kDa protein. Microvilli from different placentae revealed substantial differences regarding the intensity of the labeling of these two bands, suggesting that the antigens recognized by GB24 are probably allotypic.

Amnion↗
PubMed1988

[A multi-factorial approach in the vital prognosis of spontaneous intracerebral hematoma].

The prognostic assessment of a patient with intra-cerebral hemorrhage (IH) requires simultaneous appraisal of several parameters. We have attempted this with a multivariate method: discriminant analysis. We studied retrospectively 142 patients with non-operated IH, not due to vascular malformation, distributed two months after the initial event in two groups: 92 living patients and 50 dead. Discriminant analysis of 21 parameters from the initial examination and CT scan, selected five factors which best separate the two groups, since 89% of the patients were well classified. These five parameters (age, consciousness impairment, temperature, volume of the hematoma and ventricular hemorrhage) combined, give a prognostic score which gives for each patient his probability of survival or death. The validity of the proposed model was controlled on a test-sample of 66 patients from another department. The possibility of giving a trustworthy spontaneous prognosis on the first day can enable the evaluation of the possible benefit from surgery, which we illustrated with a group of 23 operated patients.

Age Factors↗
PubMed1987

Characterization of a new surface epitope specific for human epithelial cells defined by a monoclonal antibody and application to tumor diagnosis.

In an attempt to characterize the antigens attached to cells of a line established from a human squamous cell carcinoma of the tongue (CAL 27), BALB/c mice were immunized with whole CAL 27 cells; hybridomas were then produced using spleen cells of the animals and cells of an NS1 syngeneic myeloma. A hybridoma secreting a monoclonal antibody was obtained (CALAM 27); CALAM 27 was directed against an epitope attached to the CAL 27 cells. CALAM 27, IgG2a, reacted with a membrane antigen specific to all epithelial cells. After immunoprecipitation, this antigen corresponded to two bands (Mr 22,000 and 54,000). Reactivity disappeared when the tissue was embedded in paraffin but was conserved after fixation with acetone or methanol. This antigen was conserved for both benign and malignant epithelial cell pathologies. The action of CALAM 27 was tested on 80 samples of pleural effusions, ascites, and cerebrospinal fluid samples; after conventional cytological examinations, CALAM 27 failed to recognize either reactive mesothelial cells or meningothelial cells. In addition, the cell structure recognized by CALAM 27 is not found on certain lymphoid tissue cells. CALAM 27 also failed to react with small cell carcinoma of the lung. Its strictly epithelial specificity therefore permits its use for the diagnosis of micrometastases of carcinoma in ascites and cerebrospinal fluid, in pleural effusions, and in bone marrow. CALAM 27 may also prove useful in confirming diagnosis of pathologies suspected to be of epithelial origin.

Animals↗
PubMed1987

Internalization of insulin receptors and HLA antigens in human hepatoma cells.

Human HepG2 hepatoma cells express a high number of insulin receptors. Growing cells exhibit 70% of their insulin receptors on the plasma membrane. Moreover, cell-surface insulin receptors form molecular complexes with class I major histocompatibility antigens, as determined by co-immunoprecipitation of the receptors by anti-class I monoclonal antibodies. On exposure to saturating concentrations of insulin, the hormone is rapidly internalized into a Pronase-resistant compartment. Internalization of insulin is accompanied by a rapid (t1/2 = 2-3 min) redistribution of insulin receptors from the cell surface to an intracellular compartment. On removal of insulin from the medium, functional receptors recycle back to the plasma membrane, where they can bind insulin again. With chronic exposure of HepG2 cells to insulin, the initial redistribution of receptors is followed by a slow (t1/2 = 9 h) down-regulation of the receptors. Finally, notwithstanding their interaction at the cell surface, insulin receptors and class I major histocompatibility antigens are internalized at different rates and with independent regulation.

Carcinoma, Hepatocellular↗
PubMed1987

Radiopaque markers transit and anorectal manometry in 16 patients with multiple sclerosis and urinary bladder dysfunction.

Fecal incontinence and/or constipation are frequent complaints in multiple sclerosis associated with urinary bladder dysfunction, incontinence, and/or retention. Total and segmental colonic transit were studied by determination of radiopaque markers, and anorectal function by anorectal manometry, in 16 multiple sclerosis patients clinically defined (with urinary bladder dysfunction shown by urodynamic examination). Fifteen multiple sclerosis patients had constipation and 14 had increased colonic transit time; ten multiple sclerosis patients had fecal incontinence and five had spontaneous rectal contractions. It is suggested that increased colonic transit and anorectal dysfunction were secondary to neurologic disorders just as urinary bladder dysfunction is due to neurologic disorders in multiple sclerosis.

Adult↗
PubMed1987

Indexes of severity for osteoarthritis of the hip and knee. Validation--value in comparison with other assessment tests.

The index for hip disease (ISH) was established, validated and appraised as a new assessment test for the trial of new drugs as well as for long-term follow-up of patients, and to help with future indications for surgery. The ISH deals with pain, maximum walking distance, and some activities of daily living. Inter-observer reproducibility is good (mean deviation 0.55 points; p less than 0.05). In a short-term, double-blind crossover trial, the ISH, judged according to its power to distinguish between the active drug period and the placebo period, appears as one of the best assessment tests. In the long term, total hip prosthesis is most often justified when the ISH score reaches 10-12 points. The index of severity for knee disease (ISK) was validated and appraised by the same statistical methods. Its value in non-steroidal anti-inflammatory drug (NSAID) or analgesic trials is lower than the value of the ISH. However, its use is still justified for that purpose, and for long-term follow-up of osteoarthritis of the knee.

Hip Joint↗
PubMed1986

Cross-linking of insulin receptors to MHC antigens in human B lymphocytes: evidence for selective molecular interactions.

Molecular interactions between insulin receptors and MHC antigens were investigated in human B cells. Two B lymphoblastoid cell lines, IM-9 and 526, chosen for their high insulin binding capacity, were found to express 15,000 and 25,000 insulin receptors per cell, respectively. Insulin receptors were labeled with a 125I-photoreactive insulin analogue, and all other surface proteins by lactoperoxidase-catalyzed radioiodination. Neighbor proteins were cross-linked with a cleavable homobifunctional reagent dithio-bis-(succinimidyl propionate) (DSP) and solubilized before immunoprecipitation by anti-HLA monoclonal antibodies. Gel analysis of the precipitated proteins showed that 90% of insulin receptors precipitable by anti-insulin receptor antibodies were precipitated by anti-class I antibodies (anti-heavy chain and anti-beta 2-microglobulin) after cross-linking with 2 mM DSP. In neither IM-9- nor 526 cells could HLA antigens be precipitated by anti-insulin receptor antibodies, suggesting that the concentration of class I antigens largely exceeds the concentration of insulin receptors at the cell surface. In 526 lymphocytes, class I MHC antigens were also found to adjoin class II antigens, since both molecules could be coprecipitated with anti-HLA A, B, C and with anti-HLA-DR antibodies after chemical cross-linking. Down-regulation of insulin receptors by chronic exposure of IM-9 cells to insulin did not affect the amount of MHC molecules present on the cell surface, and conversely, class I MHC molecules were internalized in 526 cells irrespective of the presence of insulin. These results thus show that insulin receptors and MHC antigens form multimolecular complexes in the plasma membrane of cultured human B cells. These interactions, which do not appear to influence the regulation of these proteins on the cell surface, may be involved in the mechanism of hormone signaling.

B-Lymphocytes↗
PubMed1986

Pointing with left vs right hand in left visual field neglect.

The authors report the detection performances of three subjects with unilateral left visual neglect as they were submitted to a closed-loop manual pointing task in the reaching field. Results show, for all three subjects, better detection performances when manual pointing was executed with the left hand--i.e. contralateral to the lesion--than when made with the right hand. Given that, for both hands, signal detection conditions were the same, these results are discussed according to: other studies having showed changes in the expression of neglect as induced by changes in the nature or the strategy of the task; the concept of an indissociable sensorimotor central processing; and one of the models put forward to account for unilateral spatial neglect which includes a motor representation.

Aged↗