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Biomedical subjects

F Becker

Publications and source records attributed to F Becker.

At least 91 records · Page 5Linked to original sources
PubMed1994

[Carotid surgery without systematic preliminary angiography. 402 patients treated by surgery between 1986 and 1992].

Ultrasonography of the carotid bifurcation is a high performance technique for the detection of carotids stenosis. Associated with Doppler and echography, ultrasonography offers a means of precisely evaluating atheromatous stenoses of the bifurcation. The degree of narrowing can be calculated from the pulsed Doppler recordings and colour echo-Doppler measurements, reducing the subjective interpretation factor (the operator-dependent nature of the exploration is no longer related to data collection). Most severe stenoses can be diagnosed with these techniques. The question now is whether carotid angiography is still necessary to establish the indication for surgical endarterectomy. We attempted to give an answer based on our prospective series of 402 endarterectomies of the carotid bifurcation performed between 1986 and 1992 without prior routine angiography. Arteriography was performed occasionally in the pre-operative work-up but was limited to cases in which the ultrasonography was judged insufficient. We observed a mortality of 0.25% and a morbidity of 0.5%. This diagnostic approach is justified by its lower cost and reduced risk due to arteriography. In addition, unidentified arterial lesions downstream have little or no effect on indications and outcome.

Aged↗
PubMed1993

Use of a reporter transgene to generate arabidopsis mutants in ubiquitin-dependent protein degradation.

Ubiquitin-dependent proteolysis is a major proteolytic pathway in the cytoplasm and nucleus of eukaryotic cells. We introduced a gene encoding a substrate for this pathway into the genome of Arabidopsis thaliana. The transgene codes for a hybrid protein consisting of dihydrofolate reductase (DHFR, EC 1.5.1.3) fused to a degradation signal that is specifically recognized by components of the ubiquitin-dependent proteolysis pathway. Elevated concentrations of the DHFR protein confer resistance to the drug methotrexate, but rapid degradation prevents accumulation of the protein in the plant. Therefore, transgenic A. thaliana lines expressing the DHFR fusion protein are methotrexate-sensitive. Selection for mutants resistant to methotrexate resulted in plants impaired in degradation of the DHFR model substrate, as shown by an increase in protein level in the mutants.

Journal Article↗
PubMed1993

[Increased activation of CD8-positive lymphocytes in patients with Crohn's disease].

CD8+ (suppressor/cytotoxic) T lymphocyte subpopulations were studied in the peripheral blood of patients with Crohn's disease by flow cytometry analysis. Consistent with earlier reports, increased numbers of CD8+CD57+ cells were observed as compared with controls. However, expanded CD8+CD57+ cells were not found to be present in a distinct clinical subset of patients. A substantial number of patients had enhanced numbers of DR+ and CD45RO CD8+ cells. In addition, high numbers of CD8+ cells which were CD57CD45RO double positive, and a correlation between numbers of CD8+CD57+ and CD8+DR+ lymphocytes were detected. By use of an enzyme immunoassay, significantly elevated levels of soluble CD8 antigen were demonstrated in patients' sera, and results were associated with ESR values. Taken together, the data suggest increased activation of CD8+ lymphocytes which might result from systemic disease activity. Disturbances within CD8+ lymphocytes do not seem to be specific to Crohn's disease since similar alterations could be observed in patients with another inflammatory condition, rheumatoid arthritis.

Adolescent↗
PubMed1993

Transcutaneous oxygen pressure. An effective measure for prosthesis fitting on below-knee amputations.

After amputation for arterial occlusive disease of the lower limbs, healing and local adaptation to a prosthesis depend on the oxygen ratio in the tissue. Transcutaneous oxygen tension (TcPO2) is a noninvasive microcirculatory exploration. Forty six below-knee stumps were selected without any prosthetic problem excepting vascular, with a follow-up mean duration of 23 months. They were classified into different prosthetic categories. The first was the worst because it required further amputation on the thigh and the fourth the best, which displayed complete adaptation to a socket contact. These groups were related to their TcPO2 values on the anterior and exterior face of the stumps in both reclined and seated positions. It seems that it is impossible to achieve healing when the TcPO2 value is lower than 15 mm Hg in lying position. However, healing is possible above 20 mm Hg but socket contact is not possible when TcPO2 values are under 40 mm Hg. When TcPO2 values are above 40 mm Hg, a good prosthesis fitting is possible when no problems are encountered other than vascular ones.

Aged↗
PubMed1992

Vascular manifestations in homocystinuria.

Homocystinuria was discovered in a 21-year-old woman when she presented with lower limb ischemia and pulmonary embolism. This patient had a partial deficit in cystathionine-synthetase and took strongly dosed oral contraceptive medication. This report underscores: (1) the value of searching for this type of pathology even in the adult; (2) the possibility of disclosure by another condition, and particularly, drug-induced; (3) the importance of searching for other involved members of the same family; and (4) the possibility of treatment in vitamin sensitive patients.

Adult↗
PubMed1992

Pressure of lymphatic capillaries in human skin.

The network of lymphatic capillaries of the human skin was depicted at the distal part of the tibial plateau by fluorescence microlymphography (fluorescein isothiocyanate-dextran 150,000). Intralymphatic pressure was determined in 28 lymphatic capillaries of 21 healthy volunteers (mean diameter 56.0 +/- 10.0 microns) by a servo-nulling pressure system. It averaged 4.0 +/- 4.5 mmHg (range: -6.8 to +10.7 mmHg). These are the first measurements of pressure in the initial lymphatics of human skin and form a basis with which to compare measurements made in patients with different forms of edema.

Adult↗
PubMed1992

[Post-thrombotic venous disease of the legs. Current data].

The post-thrombotic syndrome (PTS) is the first cause of the severe chronic venous insufficiency (CVI) of which the total cost is very high. The lack of precise definitions, the long latency time between the deep vein thrombosis (DVT) and the trophic changes, the difficulties in treating the post-thrombotic ulcers, are partly responsible for the difficulties in analysing the problem of the PTS (epidemiology, pathophysiology, exploration) and consequently for the lack of interest in this disease. The recent data show that: 1) trophic venous changes are not all of PTS origin, 2) calf DVT are not to be neglected concerning the PTS risk, 3) the calf deep valvular destruction and the calf perforating veins reflux play the first part in the PTS evolution, 4) we should take into consideration the whole venous hemodynamic function of the lower limbs (macro and microcirculation) when analysing the long term clinical and hemodynamical consequences of a DVT. Today, the best treatment of a PTS is still its prevention not only by a better diagnosis and treatment of DVT but also by a long term ambulatory elastic stocking therapy with the aim of prolonging the disease-free interval.

Humans↗
PubMed1991

Purification of tobacco nuclear proteins binding to a CACGTG motif of the chalcone synthase promoter by DNA affinity chromatography.

The activity of various light-regulated and developmentally regulated plant gene promoters critically depends upon the presence of a conserved sequence with a central CACGTG motif. Using band-shift assays, we have identified nuclear factor(s) from Nicotiana tabacum, termed CG-1, that specifically recognize(s) this transcriptional element in the ultraviolet-light-regulated Antirrhinum majus chalcone synthase promoter. CG-1 activity is constitutively expressed in tobacco seedlings grown in the absence of ultraviolet light as well as in seedlings induced for chalcone synthase gene expression by ultraviolet light irradiation. CG-1 activity has also been detected in flower tissue. DNA-protein cross-linking studies identified three polypeptides with apparent molecular masses of 20, 32 and 42 kDa binding to the CACGTG motif. Proteins interacting with the CACGTG motif were purified from N. tabacum seedlings using differential sequence-specific DNA affinity chromatography employing wild-type and mutated CG-1-binding sites. Denaturing polyacrylamide gel electrophoresis revealed major polypeptides of approximately 20, 30 and 40 kDa which are highly enriched in the affinity-purified fractions binding specifically to the CACGTG motif.

Acyltransferases↗
PubMed1991

Progression to type I diabetes in autoimmune endocrine patients with islet cell antibodies.

In an 11-yr screening program carried out on serum samples sent to an autoimmune serology laboratory, 158 patients with clinical or subclinical autoimmune endocrine manifestations and islet cell antibodies (ICAs) in the absence of overt diabetes were identified and followed for the development of insulin-dependent (type I) diabetes. Twenty-two (13.9%) developed type I diabetes in a follow-up of up to 12 yr (mean +/- SE 4.8 +/- 3.2 yr). The probability of being free of type I diabetes was 69.8% at 10 yr after the first detection of ICAs. Progression to disease was influenced by 1) the amount of ICAs represented by high titers (63% of those with ICAs greater than or equal to 20 Juvenile Diabetes Foundation units being free of type I diabetes at 10 yr), ICA persistency (59% being free of type I diabetes; P less than 0.02 vs. nonpersistent ICA), and complement-fixing (CF)-ICAs (63% being free of type I diabetes; P less than 0.05 vs. non-CF-ICA); 2) the coexistence of insulin autoantibodies (IAAs) (25% being free of type I diabetes; P less than 0.005 vs. IAA-); and 3) a positive family history (1st-degree relative) for type I diabetes (32% being free of type I diabetes; P less than 0.005 vs. no family history). There was a trend for diabetes to develop earlier in males of a younger age. No relationships were found with the number, type, or clinical expression of the associated autoimmunities or with a family history of such disorders.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Heparin-induced thrombocytopenia. Practical management of vascular complications].

The authors report 23 cases of heparin-induced thrombocytopenia with vascular complications. The clinical presentation consisted of arterial ischaemia in 16 cases, hemiplegia in 1 case, 4 cases of blue thrombophlebitis, 1 case of bilateral thrombophlebitis, 1 case of pulmonary embolism. The vascular surgeon faced with such emergency complications must be aware of the difficulties of clinical (atypical forms) and laboratory diagnosis (unreliability of platelet aggregability tests). Arterial occlusions are generally accessible to treatment with a Fogarty catheter during an operation performed without the use of heparin. The excessively frequent delay in diagnosis explains the severity of these complications and 2 deaths, 1 case of paraplegia, 4 cases of amputation secondary to arterial occlusion, 4 cases of severe postphlebitis disease, including 2 cases requiring transmetatarsal amputation and one case of pulmonary sequelae after pulmonary embolism were observed in our series of 23 patients. The diagnosis of heparin-induced thrombocytopenia requires immediate discontinuation of heparin therapy. Replacement by low molecular weight heparin is not devoid or risks and can only be considered with a negative platelet aggregability test (in the presence of low molecular weight heparin). As these test can be rarely performed as an emergency procedure, the use of rapid-acting oral anticoagulants appears to be the most reliable solution. The place of platelet antiaggregants and partial interruption of the inferior vena cava is discussed.

Adult↗
PubMed1991

[Autoantigens in type-I diabetes].

The juvenile form of diabetes, type-I diabetes mellitus, is, to our knowledge of today, an autoimmune disease with the hallmark of selective destruction of the insulin-producing beta cells in the endocrine pancreas. The slow, progressive process is in strong contrast with the sudden onset of clinical disease. The identification of target antigens has implications for both, better diagnostic at an earlier time as well as for new forms of therapy such as induction of tolerance or T-cell vaccination. Next to the direct products of the beta cell, insulin and proinsulin, two antigens of 38 resp. 64 kD molecular weight, have been identified. Other possible antigens include carboxypeptidase H and a heat-shock protein of 65 kD. The identity of the antigen recognized by islet-cell antibodies, the most frequently used marker for type-I diabetes mellitus, remains a subject of discussion.

Autoantibodies↗
PubMed1990

[Insulin and immunology--a correlation].

In comparison to former decenniums the relations between insulin and immunology have changed and continued to develop. Still up to 20 years ago the immunological side effects of an insulin therapy stood well to the fore concerning the clinical interest, nowadays, however, they are the autoantibodies against insulin and it is the role of insulin for a functioning immune system, which is not in the least exactly recognized.

Animals↗
PubMed1990

[A "non-narrowing" patch using the superior thyroid artery in surgery of carotid arteries].

It seems to be generally agreed that a closing patch is necessary after carotid endarterectomy. The materials utilized (prostheses or veins) having their own morbidity, we prefer to use a piece taken from the superior thyroid artery; Satisfactory results were obtained in the first 26 cases. This autologous biological material has the advantage of being an arterial structure (therefore compatible with the sutured artery) which is obtained in situ and spares the venous system.

Arteries↗
PubMed1990

Perturbation of the ubiquitin system causes leaf curling, vascular tissue alterations and necrotic lesions in a higher plant.

A ubiquitin variant with Lys48 changed to Arg acts in vitro as an inhibitor of ubiquitin dependent protein degradation. To assess the role of this proteolytic pathway in the life cycle of plants, we expressed the ubiquitin variant in Nicotiana tabacum. Expression of variant mono- or polyubiquitin leads to marked abnormalities in vascular tissue. In addition, overexpression of variant polyubiquitin induces discrete lesions on leaves. This indicates that perturbations of the ubiquitin system can induce a programmed necrotic response in plants.

Arginine↗