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Biomedical subjects

C Boyer

Publications and source records attributed to C Boyer.

At least 145 records · Page 8Linked to original sources
PubMed1976

[Atrioventricular "sequential" stimulation by implantable "bifocal" stimulator].

The "bifocal pacemaker achieves a sequential" stimulation which reproduces the physiological atrio-ventricular sequence. This type of stimulation has the advantages of atrial stimulation without the disadvantages of being inefficient when an atrio-ventricular block exists or supervenes. The pacemaker was used by the endocavity route in 12 patients. The indications included a disease of the sinus node (8 cases), supra-ventricular arrhythmias associated to conduction disorders (3 cases) and a cardiomyopathy with conduction disorders (1 case). The preliminary results were appraised after two to twenty four months. One displacement of the ventricular electrode was noted. On the other hand no displacement of the atrial electrode was reported. One battery was worn out after 19 months. The "bifocal" pacemaker was efficient in the treatment of symptoms which justified its implantation. Or particular interest were the results obtained in patients with no supraventricular arrhythmias. This pacemaker may be of use: 1) in the disease of the sinus node, in particular in the tachycardia-bradycardia syndrome; 2) in supraventricular arrhythmias associated to paroxystic conduction disorders; 3)in patients with an alteration of the myocardial function and for whom the atrial contribution to cardiac output is essential.

Aged↗
PubMedDate not supplied

Inherited deficiency of antithrombin III in an Italian kindred.

Life-long symptoms of venous thromboembolism were present throughout five generations in a large Italian kindred. Eight out of the 22 tested members of the family had reduced plasma levels of antithrombin III (AT III), the main physiological inhibitor of blood coagulation. Three of them, aged 2-28 years, but no thrombotic manifestations. AT III deficiency, which was hitherto thought to be very rare in this country, appeared to be related to a reduced synthesis of the protein without any qualitative abnormality. This view is supported by the concomitant reduction of AT III levels as demonstrated by biological and immunological assays, as well as by a normal pattern of the protein in double-crossed immunoelectrophoresis with and without heparin added to the agarose gel. Long-term treatment with oral anticoagulants appeared to prevent further thromboembolic episodes in two patients, even though plasma AT III levels remained unchanged.

Adolescent↗
PubMedDate not supplied

Phosphorylation of T-cell antigen receptor-associated proteins: correlation with activation for killing and/or for gamma-interferon production by a cytolytic T-cell clone.

The activation-induced phosphorylation of T-cell antigen receptor (Ti)-associated proteins was investigated in order to analyse possible signal-transduction mechanisms leading to two distinct effector functions of a mouse cytolytic T-cell clone (KB5.C20): target cell killing (independent of protein synthesis) and de novo production of gamma interferon (gIFN; dependent on gIFN gene expression). Ti-associated T3-like proteins were first identified by immunoprecipitation of 125I-labelled cell surface proteins from 1% digitonin lysates of clone KB5.C20 by 1- and 2-dimensional (non-reduced (NR)/reduced (R)) gel electrophoresis. In addition to the alpha and beta chains of the Ti (NR: 80-Kd; R: 43 and 40 Kd), two doublets of 35-37 Kd (NR) and 32-34 Kd (NR) leading to bands of 25, 16 and 14 Kd (R) were identified, as well as three bands (25, 23 and 22 Kd (NR)) leading to 27-, 25- and 21-Kd bands (R). Activation of clone KB5.C20 (prelabelled with 32P-orthophosphate) with either anti-Ti mAb or exposure to both ionomycin and phorbol myristic acetate (PMA) induced the phosphorylation of 21- and 25-27-Kd (R) Ti-associated proteins, whereas exposure to either ionomycin or PMA alone induced only weak phosphorylation of 21-Kd (R) components. A weak phosphorylation of 32- and 34-Kd Ti-associated proteins was sometimes observed after stimulation with anti-Ti mAb. Functional studies suggested that activation for gIFN production was observed only when both the 21- and 25-27-Kd proteins were phosphorylated, whereas activation for killing (when measured by PMA-induced non-specific killing) could occur in conditions where no phosphorylation of the 25-27-Kd protein was detected.

Antibodies, Monoclonal↗
PubMedDate not supplied

Pleiotropic loss of activation pathways in a T-cell receptor alpha-chain deletion variant of a cytolytic T-cell clone.

Untransformed T-cell clones maintained in culture are dependent on signals transmitted through their antigen receptors (Ti; alpha and beta chains associated with the CD3 molecules) for growth and effector function. For cytolytic T cells (CTL), Ti stimulation also activates the killing machinery and induces synthesis of gamma interferon (IFN-gamma) messenger RNA and IFN-gamma secretion. The Thy-1 molecule, expressed on all murine cells of the T-cell lineage, has been suggested to function in transmembrane signalling, based on the ability of some anti-Thy-1 monoclonal antibodies (mAb) to activate T cells. Recently, it was suggested that Thy-1 could function as a signal-transduction molecule when expressed in B-cell lymphomas after transfection of the gene, leading to speculation that the molecule was part of an activation pathway independent of the Ti/CD3 structures. Here we report the immunoselection of a variant CTL clone which has lost expression of mRNA for the alpha-chain of the Ti. The Ti- variant was defective in lectin-mediated activation whether measured by increase in intracytoplasmic Ca2+, CTL effector function or IFN-gamma synthesis. The variant, which expressed normal levels of Thy-1, was also unresponsive to Thy-1 mAb activation as measured by IFN-gamma secretion, whereas it responded to calcium ionophore plus phorbol ester. These results indicate that in a non-transformed, functional mature T-cell, Thy-1 mediated signalling is not an alternative to, but might depend on elements associated with the Ti/CD3-mediated T-cell activation pathway.

Antibodies, Monoclonal↗
PubMedDate not supplied

Synthesis and biological evaluation of boronated nucleosides for boron neutron capture therapy (BNCT) of cancer.

Several N-3 substituted carboranyl Thd analogs were synthesized. These agents as well as some non-boronated nucleosides were evaluated in phosphoryl transfer assays with recombinant human TK1 and TK2. For some carboranyl thymidine analogs, TK1 phosphorylation rates approached 38% that of thymidine. Their in vitro cytotoxicty appeared to correlate with the TK1 levels in the tested cells. In some cases increased uptake in tumor cell nuclei compared with the surrounding cytoplasm was detected in vitro.

Boron Compounds↗
PubMedDate not supplied

MARVIN, multi-agent softbot to retrieve multilingual medical information on the Web.

The World-Wide Web is an unstructured, multimedia and multilingual information network. While most efforts have addressed the structuring issue, very few attempts have been proposed to provide support for multilingual information retrieval. Yet, medical information is now available all over the world. The MARVIN (Multi-Agent Retrieval Vagabond on Information Network) softbot and its associated medical search engine MedHunt (Medical Hunter) are a solution for helping people, who only understand a few languages, to access multilingual information.

Information Storage and Retrieval↗
PubMedDate not supplied

Charm Safe-Level beta-Lactam Test for amoxicillin, ampicillin, ceftiofur, cephapirin, and penicillin G in raw commingled milk.

The Charm Safe-Level beta-Lactam Test was evaluated by a U.S. Food and Drug Administration (FDA) test protocol administered by the AOAC-Research Institute. The sensitivity and selectivity of the test were evaluated with >800 negative raw commingled and drug-fortified milk samples by the manufacturer and an independent laboratory. Probit analysis by the independent laboratory determined the following 90% positive levels with 95% confidence: amoxicillin, 5.6 ppb; ampicillin, 8.5 ppb; cephapirin, 13.7 ppb; ceftiofur, 46.2 ppb; and penicillin G, 3.6 ppb. These values were within a range of +/- 20% of the manufacturer's data. Selection of negative samples met confidence specifications. Ruggedness parameters were studied and defined, and the stability of frozen milk was verified. There were no interferences from somatic cells (1,000,000 somatic cell count/mL) or bacteria (300,000 colony-forming units/mL), or from 27 other non-beta-lactam animal drugs. Test performance with raw milk samples containing incurred penicillin, ampicillin, and amoxicillin was consistent with the dose responses determined with fortified milk samples. Incurred cephalosporin in raw milk samples was detected at lower levels than was cephalosporin in fortified milk samples, presumably because of the presence of metabolite, as verified by other test methods. Quality control data support consistency in manufacture between batches and the stability of refrigerated test reagents for up to 1 year. Successful fulfillment of these criteria led to FDA certification of the test when used with a reader in U.S. milk testing programs.

Amoxicillin↗
PubMedDate not supplied

[Favorable course of a bilateral postoperative diaphragmatic paralysis].

Writing about a case of post-operative diaphragmatic bilateral palsy (bilateral thoracotomies for oesocoloplasty and oesophagectomy necessited by a caustic oesophagitis) on a 8 years old boy, palsy which was cured 6 months after, the authors tell about causes, prognostic and treatment of diaphragmatic palsies. In that observation, treatment consisted essentially in artificial ventilation for months and a half, and on intensive kinesitherapy.

Abdomen↗
PubMedDate not supplied

[Obstetrics-gynecology].

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Diagnostic Techniques, Obstetrical and Gynecologic↗
PubMedDate not supplied

[Pediatric imaging].

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Bone Diseases↗
PubMedDate not supplied

[When the leg is the victim of the foot].

Man (homo-erectus, plantigrade) is in constant contact with the ground via his feet which are platforms on which the legs and, above all, the entire body rest. When the body moves, the only segment which remains stable and fixed is the foot, which forms the point of departure of all the muscular actions of this moving body. The slightest deformity of this platform, this foot, will lead to skeletal, musculotendinous and neurovascular problems in the legs, and to pain. Pain due to skeletal problems may be related to fatigue fractures (tibia, fibula) and to posterior tibial periostitis. Pain may also be due to musculotendinous problems which are characterised by a muscle bed syndrome (anterolateral, posterior) or tensosynovitis. Neurovascular problems are typified by a tarsal sinus syndrome, a musculocutaneous nerve syndrome and dysfunction of Lejears' sole during filling in flat feet and during emptying in hollow feet.

Foot Diseases↗