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Biomedical subjects

S Weber

Publications and source records attributed to S Weber.

At least 235 records · Page 13Linked to original sources
PubMed1991

Expression of GTP-binding proteins and prostaglandin E2 receptors during human T cell activation.

GTP-binding proteins (G-proteins) are a family of closely related, yet structurally distinct signal transducing proteins. In this study the presence and relative abundance of several G-proteins and of their corresponding mRNAs were measured in resting and activated human T lymphocytes. We found that T lymphocytes contain RNA coding for Gs, Gi2, and Gi3. No Gi1- and Go-specific RNA could be detected. Membrane fractions of resting and activated lymphocytes were studied in immunoblot experiments. Again, Gs, Gi2, and Gi3, but not Gi1 and Go, were detected. Upon mitogenic activation, a relative increase in mRNA for Gs and Gi3, but not for Gi2 could be demonstrated in Northern blot experiments. Immunoblotting indicated an increase in Gs and Gi3 density in membrane fractions of T cells as well. Paralleling the increase in Gs, we found that activated T cells produce five to seven times more cAMP per cell in response to prostaglandin E2 (PGE2) than resting lymphocytes. Finally, PGE2 binding studies showed that the number of receptors for this hormone increased from 435 +/- 322 to 1035 +/- 357 per cell following in vitro stimulation. We propose that in vitro T cell activation is paralleled by an increase in sensitivity to PGE2-induced cAMP generation. This sensitization is accompanied by both an increase in cell surface PGE2 receptor numbers as well as by increased expression of the signal transducing protein Gs and may physiologically be important for limiting an immune response.

Cyclic AMP↗
PubMed1991

Intravascular coagulation necrosis of the skin associated with cryofibrinogenemia, diabetes mellitus, and cardiolipin autoantibodies.

Intravascular coagulation necrosis of the skin is rare and appears as hemorrhagic infiltrates that may develop ulcerating necrosis, mainly on the acral areas. The face, arms, and legs were severely involved in our patient. In this patient intravascular coagulation necrosis was associated with cryofibrinogenemia, diabetes mellitus, and IgM cardiolipin autoantibodies. In addition, rheumatoid factor, elevated polyclonal IgA, and haptoglobin were present as risk factors for the vasculopathy. Skin biopsy specimens showed plugging of dermal venules by thrombi formed of fibrin and erythrocytes. Immunohistologic staining revealed a strong positive reaction for fibrinogen, with some positivity for C3, C4, IgG, IgA, and IgM. Erythrocyte extravasation occurred in late lesions without being accompanied by perivascular leukocytic infiltrates. Detailed clinical examination failed to identify an underlying malignancy. Treatment with heparin and prednisolone produced only a brief remission. However, the combination of chlorambucil (7 mg/day orally) with low-dose oral prednisolone (10 mg/day) for several weeks controlled the disease and greatly reduced the cryofibrinogen. No relapse occurred after discontinuation of treatment.

Aged↗
PubMed1991

[Effect of sinorphan, an endopeptidase inhibitor on severe congestive cardiac insufficiency].

Sinorphan is a powerful inhibitor of enkephalinases or endopeptidases 24-11, enzymes implicated in the degradation of the atrial natriuretic factor (ANF). In healthy volunteers, it increases plasma concentrations of endogenic ANF and increases diuresis and natriuresis. In order to study the tolerance and biological effects of pharmacological increase of plasma concentrations of endogenic ANF in severe congestive cardiac failure, 12 patients (in functional Classes III or IV of the NYHA classification) were given a single oral dose of 10, 20 or 40 mg of Sinorphan. Sinorphan was clinically well tolerated. The diastolic blood pressure decreased slightly (- 10 +/- 9 mmHg) but significantly (p less than 0.05). Systolic blood pressure and heart rate were unchanged. Despite spontaneously high plasma ANF concentrations (on average 15 times higher than normal subjects), Sinorphan induced an additional increase of 80 to 100% of plasma ANF concentration compared to the initial values (p less than 0.01) with no dose-dependent response for the dosages used. The inhibition of plasma endopeptidase activity attained 47% at the 30th minute. Urinary cyclic GMP excretion increased by 30% at the second hour (p less than 0.05). In addition, a statistically non significant tendency to increase diuresis and natriuresis was observed. These results show that Sinorphan increases plasma ANF concentrations by inhibition of its degradation in severe congestive cardiac failure and that this increase seems to be associated with potentially beneficial biological changes. The concept of endopeptidase inhibition should constitute a new therapeutic approach in cardiac failure, a situation in which the ANF seems to exert a favourable effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Immunohistochemical studies of bronchial carcinoma using monoclonal antibody A63-C/A3].

An immunohistological study was undertaken, using paraffin sections of 22 cases of lung carcinoma and a number of reference tissue samples, to clear up the reactivity of A63-C/A63 monoclonal antibody (IgM) which was capable of identifying a carcinoma-associated carbohydrate antigen. Following neuraminidase pretreatment of those sections, positive response to the above antigen was produced by more than 90% of all bronchial carcinoma samples, notwithstanding the histological type involved (squamous-cell carcinoma or adenocarcinoma). Columnar epithelium of the bronchi, not involved in the neoplastic process gave a positive immunoreaction with the antibody A63-C/A3 in 64% of the cases.

Adenocarcinoma↗
PubMed1991

[The resistance behavior of yeast isolates from defined patient groups to 5-fluorocytosine].

Susceptibility and development of resistance to 5-FC in Candida strains isolated from 4 defined groups of probands was investigated. 5-FC-susceptibility was determined in a microdilution assay in yeast nitrogen base after 24 h incubation at 37 degrees C. The range investigated ranked between 5-FC-concentrations from 0.015-16 microgram ml-1. Isolates with an MIC of greater than or equal to 16 micrograms ml-1 were regarded as 5-FC-resistant. In total 336 Candida isolates were investigated; 21 of them (= 6.3%) were found to be 5-FC-resistant. The Candida isolates were rather different with respect of their origin: 57 vaginal isolates from non-risk patients from Southern Germany comprised 5.3% 5-FC-resistant strains. 160 isolates from the urine of longtime-intensive care patients of total Germany were 5-FC-resistant with 6.3%. Of 74 isolates of different localization from intensive care patients of the University Clinics in Freiburg 10.8% were 5-FC-resistant. Among 45 isolates from the oral cavity from HIV-positive patients of the Frankfurt region no 5-FC-resistant strain was found. The epidemiology of 5-FC-resistance is mainly based on the percentage of non-albicans isolates of the proband groups (C. tropicalis, C. krusei and others), and is less based on the frequency of C. albicans serotype B isolates. In sequential observations with individual intensive care patients no increase of 5-FC-resistance in their Candida isolates could be observed with longer periods of hospitalization.

Candida↗
PubMed1991

[Chronic immunoproliferative syndromes].

Immunoproliferative syndromes are etiologically unclear, rare diseases which involve polyclonal B- and/or T-cell proliferations and frequently develop into malignant non-Hodgkin-lymphoma. Typically, these diseases are characterized by lymphadenopathies, hepatosplenomegaly, general fatigue and autoimmune phenomena. Here we briefly outline 6 syndromes, two of which--the "pluripotential chronic immunoproliferative syndrome" (CPIS) and the "angioimmunoblastic lymphadenopathy" (AILD)--are discussed in more detail. We favor the notion that CPIS is a variant form of AILD clinically dominated by severe autoimmune hemolytic anemia. Both diseases share the high frequency of anti-cytoskeleton autoantibodies.

Chronic Disease↗
PubMed1990

[The function of beta receptors in chronic left ventricular insufficiency].

Hyperactivity of the noradrenergic sympathetic system is one of the essential "compensatory"mechanisms in chronic left ventricular failure. The ensuing stimulation of myocardial beta-adrenergic receptors results in an increase of heart rate and contractility which, to some extent, counterbalances the alteration of left ventricular function, but rapidly reaches its limits: the excessive shortening of diastoles and, mostly, the increase of myocardial oxygen demand neutralize the beneficial haemodynamic effect of beta-adrenergic stimulation, especially when ischaemia is the cause of the heart failure; the chronic exposure of adrenergic receptors to noradrenaline in high concentrations leads to desensitization, to a "down regulation" which primarily affects the beta 1 receptors and spares, at least partly, the myocardial beta 2 receptors which seem to play a quantitatively important inotropic role, particularly in chronic heart failure. These new data on the physiology of the cardiac noradrenergic system have major therapeutic consequences: in practice, the positively inotropic beta-stimulants can only be used for a short period in acute episodes of heart failure; - the use of beta-blockers in low doses is now considered in the treatment of some forms of heart failure; the mechanism of their therapeutic action remains controverted, and their long-term effectiveness in a large patient population is under study; - a new pharmacological class, beta-adrenoceptor partial agonists, seems to give satisfactory clinical and haemodynamic results in mode-rate heart failure, A wider clinical evaluation is needed to determine the therapeutic role of theses new pharmacodynamic agents.

Adrenergic beta-Antagonists↗
PubMed1990

Role of tricuspid regurgitation and left ventricular damage in the treatment of right ventricular infarction-induced low cardiac output syndrome.

To evaluate, in right ventricular (RV) myocardial infarction, the role of tricuspid regurgitation (TR) and left ventricular (LV) damage and the response to treatment of low cardiac output, 20 patients were prospectively studied. Volume infusion increased cardiac output only slightly (11%, p less than 0.001), despite a dramatic increase in ventricular filling pressures. Dobutamine (4 micrograms.kg-1.min-1) markedly increased cardiac output (24%, p less than 0.001) with a decrease in ventricular filling pressures. In the 5 patients with TR, dobutamine only modestly increased cardiac output (9 vs 26%, p less than 0.001), while stroke index and LV end-diastolic dimensions decreased in comparison (-5 vs 33% and -6 vs 9%, respectively, p less than 0.001). In the absence of TR (n = 15), there was no significant difference in response to volume expansion between patients with normal (n = 7) and depressed LV ejection fraction (n = 8). In contrast, dobutamine, in patients with depressed LV function, induced a greater increase in cardiac output (38 vs 17%, p less than 0.01) and RV ejection fraction (36 vs 12%, p less than 0.05). All patients with RV infarction-induced low cardiac output responded only modestly to volume loading. Dobutamine is particularly efficacious in patients without TR who have depressed LV function by improving RV function and, consequently, LV preload. In the 5 patients with TR, increasing RV contractility failed to improve the forward stroke volume by increasing the regurgitant fraction.

Adult↗
PubMed1990

[Paroxysmal nocturnal hemoglobinuria].

Paroxysmal nocturnal hemoglobinuria, first described in the late 19th century, is an acquired disorder characterized by hemoglobinemia and hemoglobinuria. The major clinical manifestation of PNH is chronic intravascular hemolysis of various severity. Patients-mostly young adults - may also present with episodes of abdominal or back pain. Common cause of death is thrombosis especially of the hepatic veins. Granulocytopenia and thrombocytopenia may be the initial manifestation of PNH, indicating that the disorder is a primary bone-marrow disease, affecting not only the erythrocytes but also other peripheral blood cells and the haematopoietic stem cell. The course of the disease is variable. Partial complete recovery was described, but also fatal thrombosis. The major phenotypic expression of PNH is an increased susceptibility of the erythrocytes to the lytic action of complement in vitro. The enhanced complement susceptibility is most probably due to membrane defects: two membrane proteins regulating the complement cascade in PNH cells were missing, the decay-accelerating factor, DAF, inhibiting the activation of the lytic complement complex and the C8 binding protein, C8bp, which interferes with the lytic process. Aside from the lack of the complement regulators also other membrane defects have been described (e.g. of acetylcholinesterase or alkaline phosphatase). The proteins as well as DAF and C8bp are linked to the cell membrane via a phosphatidylinositol (PI) anchor, leading to the speculation that the disease results from a deficiency in the post-translational PI anchoring mechanism. The diagnosis of PNH is based on the Hamtest, but will be extended to the quantitation of the above described membrane proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Complement System Proteins↗
PubMed1990

The effect of captopril on thallium 201 myocardial perfusion in systemic sclerosis.

In systemic sclerosis, abnormalities of myocardial perfusion are common and may be caused by a disturbance of the coronary microcirculation. We evaluated the long-term effect of captopril (75 to 150 mg per day) on thallium 201 myocardial perfusion in 12 normotensive patients with systemic sclerosis. Captopril significantly decreased the mean (+/- SD) number of segments with thallium 201 myocardial perfusion defects (6.5 +/- 1.9 at baseline and 4.4 +/- 2.7 after 1 year of treatment with captopril; p less than 0.02) and increased the mean global thallium score (9.6 +/- 1.7 at baseline and 11.4 +/- 2.1 after captopril; p less than 0.05). In a control group of eight normotensive patients with systemic sclerosis who did not receive captopril, no significant modification in thallium results occurred. Side effects with captopril included hypotension (six patients), taste disturbances (one patient), and skin rash (one patient). These side effects subsided when the dosage was reduced. These findings demonstrate that captopril improves thallium 201 myocardial perfusion in patients with systemic sclerosis and may therefore have a beneficial effect on scleroderma myocardial disease.

Adult↗
PubMed1990

Pharmacodynamic effect of nicardipine on left ventricular function in systemic sclerosis.

Left ventricular dysfunction in systemic sclerosis may be due in part to myocardial ischemia caused by a disturbance in coronary microcirculation. We evaluated the pharmacodynamic effect of the calcium channel blocker nicardipine on left ventricular function assessed by radionuclide ventriculography in 20 patients with systemic sclerosis. Resting gated, blood-pool images were obtained at baseline and 90 min after 40 mg of oral nicardipine. The mean (+/- SEM) left ventricular ejection fraction significantly increased from 65.4 +/- 2.3% at baseline to 71.3 +/- 2.3% after nicardipine (p less than 0.005). The mean global defect score significantly decreased from 2.90 +/- 0.73 without nicardipine to 1.50 +/- 0.52 with nicardipine (p less than 0.01). The mean number of left ventricular sectors with severe hypokinesis significantly decreased from 0.80 +/- 0.24 at baseline to 0.20 +/- 0.09 after nicardipine (p less than 0.05). No significant side effects were observed with nicardipine. These results demonstrate short-term improvement in left ventricular function with nicardipine in patients with systemic sclerosis.

Adult↗
PubMed1990

Pharmacodynamic without pharmacokinetic interaction between cicloprolol, a partial beta 1-adrenoceptor agonist, and digoxin in healthy subjects.

1. Cicloprolol is a partial beta 1-adrenoceptor agonist considered for the treatment of patients with coronary artery disease and impaired left ventricular function. In such patients, digoxin remains in widespread use. 2. We assessed the pharmacokinetic and pharmacodynamic interaction between oral cicloprolol 50 mg day-1 and oral digoxin 0.25 mg day-1 in 10 healthy male volunteers, using a double-blind, randomised protocol, during three 8 day periods. Digoxin was given alone during the first period to reach steady state; then digoxin was given with cicloprolol or placebo during the second and third periods, according to a cross-over design. 3. No significant adverse effects were observed. 4. The pharmacokinetics of digoxin were not different significantly at the end of the placebo-digoxin and cicloprolol-digoxin periods. 5. A significant increase in minimum heart rate and mean nocturnal heart rate, assessed by 24 h Holter recordings, was observed at the end of the cicloprolol-digoxin period as compared with the placebo-digoxin period (means +/- s.e. mean, 57.1 +/- 3.2 beats min-1 vs 52.2 +/- 3.1 beats min-1, P less than 0.01; and 65.6 +/- 3.8 beats min-1 vs 59.9 +/- 3.9 beats min-1, P less than 0.01, respectively). 6. A significant increase in left ventricular ejection fraction and shortening fraction, assessed by echocardiography, was noted at the end of the cicloprolol-digoxin period as compared with the placebo-digoxin period (means +/- s.e. mean, 66.4 +/- 1.4% vs 61.3 +/- 1.2%, P less than 0.05; and 37.0 +/- 1.1% vs 33.3 +/- 0.9%, P less than 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗