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Biomedical subjects

H Richter

Publications and source records attributed to H Richter.

At least 19 recordsLinked to original sources
PubMed1992

Financing health services in Sub-Saharan Africa: options for decision makers during adjustment.

The financing of health services has become an increasingly critical and urgent issue in many developing countries particularly in Sub-Saharan Africa. This paper analyses options available to policy makers. The possible effects and side effects of strategies are described based on the experience from different countries. The dangers of simplistic solutions are discussed. A cautious approach is recommended taking into consideration the lessons learned in other regions accompanied by a careful ongoing evaluation especially regarding the ability to pay of the poorer sections of the population. Providing for equity in health care should be an important guiding principle. It therefore appears to be necessary to find an appropriate mix of public and private sector interventions with elements of cost-sharing for services and drugs, insurance schemes and more efficient use of available resources.

Africa↗
PubMed1992

Maintenance of left ventricular function (90%) after twenty-four-hour heart preservation with deferoxamine.

During 24-h in vitro heart preservation and reperfusion, irreversible tissue damage occurs caused by reactive oxygen intermediates, such as superoxide radicals, singlet oxygen, hydrogen peroxide, hydroperoxyl, hydroxyl radicals, as well as the peroxynitrite radical. Reduction of the related oxidative damage of reperfused ischemic tissue by free radical scavengers and metal chelators is of primary importance in maintaining heart function. We assessed whether deferoxamine (DFR) added to a cardioplegia solution decreased free radical formation during 24-h cold (5 degrees C) heart preservation and normothermic reperfusion (37 degrees C) in the Langendorff isolated perfused rat heart. The deferoxamine treated hearts were significantly (p less than .001) better preserved than the control hearts after 24 h of preservation with regard to recovery of left ventricular diastolic pressure, contractility (+dP/dt), relaxation (-dP/dt), creatine kinase release, and lipid peroxidation. DFR preserved cell membrane integrity and maintained 93% of left ventricular contractility. The evidence suggests that DFR reduces lipid peroxidation damage by reducing free radical formation and thereby maintaining normal coronary perfusion flow and myocardial function.

Animals↗
PubMed1992

[Risk factors of atherosclerosis--primary examination of Vienna employees].

In the course of an atherosclerosis intervention study, a basic medical check-up of 2105 out of 4800 employees of a Viennese banking house was carried out (37.1 +/- 11.0 years, 54.6% females). Apart from liver and kidney function parameters, an extensive lipid status was determined, the blood pressure was measured, and a cardiovascular-centered case history ascertained. The mean cholesterol level in females was 208.3 +/- 54 mg/dl and that in males was 226.8 +/- 61.1 mg/dl. The HDL-cholesterol level in males was 43.8 +/- 11.9 mg/dl; that in females (54.9 +/- 13.4 mg/dl) was significantly higher. The mean value of LDL-cholesterol in the entire group was 141.6 +/- 51.4 mg/dl and it was significantly higher in males, as well as in participants with known hypertension. 33.4% of the persons stated that they smoked. The obtained data will serve not only to discover potential interrelations between the individual risk factors of atherosclerosis in Austria, but also in particular as a basis for interventional strategies on the part of the company's medical services.

Adolescent↗
PubMed1991

Immobilization of soluble fibrin on factor XIIIa-coated polystyrene beads mediated by N-terminal fibronectin fragments. II. Demonstration of covalent adducts of fibrin peptide chains and fibronectin fragments.

Previous experiments had shown that the free N-terminal fibronectin 30-kDa-domain mediates binding of soluble 125I-fibrin to transamidase-coated polystyrene beads (Hörmann et al., Biol. Chem. Hoppe-Seyler 368, 669-674, 1987). Now, the formation of covalent adducts of the N-terminal fragment with fibrin peptide chains is demonstrated. Binding of soluble 125I-fibrin was performed in presence of N-terminal fibronectin 30-kDa or 70-kDa fragments. The material adsorbed was removed from the beads under reducing conditions and analysed by dodecylsulfate gel electrophoresis followed by autoradiography. The 30-kDa fragment gave rise to bands of 80 kDa and 180-200 kDa which were lacking in the products of the 70-kDa compound. Instead, they showed bands at 120 kDa and ca. 280 kDa. Evidently, those bands represented covalent adducts of fibrin peptide chains or their dimers with the 30-kDa or the 70-kDa fragment, respectively. In addition, dimeric gamma-chains and alpha-chain polymers of fibrin were present indicating partial polymerization of bead-attached fibrin.

Electrophoresis, Polyacrylamide Gel↗
PubMed1991

[Studies on the cell and tissue tolerance of a polymeric bone replacement material].

BOP (Biocompatible Osteoconductive Polymer) shows no cytotoxicity in vitro. After six months of subcutaneous implantation in mice a weak cellular tissue reaction is seen histologically. The hard tissue reaction after six months of implantation in fractured tibia bone shows less connective tissue between the implant material BOP and bone.

Animals↗
PubMed1991

[Congenital clavicular pseudarthrosis].

Three children with congenital clavicular pseudarthrosis are reported in this paper. Reference is made to indications for surgery and to the surgical approach.

Child↗
PubMed1991

[A new method of transosseous pull-out wire fixation in ligamentous injuries of the metacarpophalangeal joint of the thumb].

Surgical repair is usually indicated for rupture of the ulnar collateral ligament of the MP-joint of the thumb. The pull-out wire technique is commonly used for repair of typically distal ligamentous ruptures or avulsion fractures at the base of the proximal phalanx. The method's disadvantages include skin or soft tissue necrosis beneath the button on the radial side of the thumb. When postoperative swelling subsides, the formerly taught wire loosens and so does the repair. Because of this inherent danger, a special steel sleeve which is drawn over the wire on the radial side of the thumb until bone contact is made was developed. Thus, a strong and unyielding fixation of the ulnar collateral ligament repair or avulsed bone chip is certain. The follow-up for 41 patients treated by this technical modification is presented; there were no complications, including wound infections.

Bone Wires↗
PubMed1991

[Psychological studies of families with children and adolescents following surgery for congenital heart defects (tetralogy of Fallot and aortic coarctation)].

Sixty-two children with operated congenital heart disease (34 with tetralogy of Fallot and 28 with coarctation) ranging in age from 9 to 16 years underwent a detailed psychological examination. The results were compared with children without structural heart disease and with test norm values. The aim of the study was to check findings on intelligence and explore aspects which had been hardly considered previously (for instance learning capability, concentration, mental work-up of disease etc.). We had assumed that there were differences between the Fallot group and that of coarctation, since the former had been handicapped physically prior to surgery. There were differences in terms of logical thinking, where children with coarctation turned out to be better. As far as other variables were concerned there was no significant difference (such as behavioural features), nor was there any difference between boys and girls. The results show that psychic "problems" of cardiac children do not resolve automatically after surgery, but there may be children with persisting psychological peculiarities who require guidance, occasionally even psychotherapy.

Adolescent↗
PubMed1990

[Atherosclerosis Risk Factors Intervention Study Strass (ARIS)].

Mortality due to cardiovascular disease in Austria amounted to 53.7% of the overall mortality in 1986. Elevated cholesterol, cigarette smoking and hypertension are the main risk factors. In order to estimate the prevalence of these risk factors and to evaluate the effectiveness of intervention strategies, we started the ARIS (in Strass, Lower Austria) in 1987/88. 568 participants (56.7% female, 43.3% male) were asked some questions concerning their cardiovascular status; blood pressure and 22 laboratory parameters were measured (including the serum lipid profile). Doppler sonography of the carotid arteries was performed in participants older than 60 years of age (n = 229). The mean values were: cholesterol: 220.3 +/- 45 mg/dl, systolic blood pressure: 147 +/- 45 mmHg, diastolic blood pressure: 88 +/- 29 mmHg. The percentage of smokers was 18.7%. A positive family history of coronary heart disease was reported by 32.7%. Stenosis (greater than 50%) of the carotid artery was discovered in 7 cases. After this initial examination we started an information campaign at regular two-monthly intervals with around 100 participants a time. As a first result a changed consumer behaviour was observed with respect to foods. The effectiveness of the intervention trial will be seen on evaluation of annual follow-up examinations over a 10-year period in the first place.

Adolescent↗
PubMed1990

Binding and internalization of soluble fibrin by thrombocytes.

Binding of soluble 125I-fibrin to platelets was investigated with thrombocytes separated by gelfiltration or by sedimentation as well as in a thrombocyte concentrate. Gelfiltered platelets failed to retain 125I-fibrin within 16 hours unless they had been pretreated with factor XIIIa. In addition, a 30 kDa-component derived from the N-terminal fibronectin domain was required as a mediator. Platelets isolated by sedimentation bound some 125I-fibrin even in the absence of those cofactors. The 30 kDa-component improved binding and only this increase was sensitive to putrescine inhibition. Evidently, centrifuged platelets unlike gelfiltered ones express two pathways of fibrin binding. In a thrombocyte concentrate with platelets in their plasmatic environment 125I-fibrin was partially internalized. Engulfed radioactivity was detectable only for a limited period between 4-6 hours after substrate application suggesting that 125I-fibrin was intracellularly degraded followed by release of the fragments. The 30 kDa-component promoted internalization, while factor XIIIa improved the capacity. Thrombin inhibitors suppressed the uptake.

Blood Platelets↗
PubMed1990

Cell-binding and internalization of soluble fibrin by platelets.

Centrifuged human platelets bound soluble 125I-labelled fibrin, mediated by a plasma factor. Binding was inhibited by D-phenylalanyl-L-prolyl-L-arginyl- chloromethane (PPACK), which specifically blocks thrombin. As the binding-promoting principle was adsorbed to barium citrate, it was tentatively characterized as prothrombin, suggesting that it might be converted to thrombin at the cell surface. The peptide GRGDSP failed to inhibit binding, thus eliminating the glycoprotein IIb/IIIa complex as a receptor. Most likely, a thrombin - fibrin complex is recognized by a cell receptor, possibly protease-nexin I. In a platelet concentrate, the cells also internalized 125I-labelled fibrin, providing evidence that platelets are involved in the clearance of circulating fibrin - monomer complexes. Engulfment was again inhibited by PPACK or hirudin but not by an antibody against the glycoprotein IIb/IIIa complex.

Amino Acid Chloromethyl Ketones↗
PubMed1990

Plasma free N-terminal fibronectin 30-kDa domain as a marker of endothelial dysfunction in type 1 diabetes mellitus.

The plasma free N-terminal fibronectin 30-kDa domain was measured in 44 type 1 diabetic patients and in 20 healthy subjects. A significantly raised mean concentration of a free N-terminal fibronectin 30-kDa domain was found in plasma of diabetic patients with proliferative retinopathy as compared with healthy persons (P less than 0.001). A positive correlation was observed between free N-terminal fibronectin 30-kDa domain and von Willebrand factor in plasma of all examined subjects (r = 0.62, P less than 0.01). A similar correlation was present between 30-kDa domain and albuminuria (r = 0.56, P less than 0.01). However, no relationship was found between fibronectin 30-kDa domain and control of diabetes as assessed by fructosamine concentration. The free N-terminal fibronectin 30-kDa domain may be used as a marker of actual endothelial cell dysfunction in diabetes.

Adult↗
PubMed1990

Differential expansion of human endothelial monolayers on basement membrane and interstitial collagens, laminin and fibronectin in vitro.

In this study the ability of a human endothelial cell monolayer to expand over specific components of the basement membrane and extracellular matrix was investigated over a 5-day period. The method was intended as a model to study the mechanisms of endothelial regeneration. All components were coated onto sterile coverslips at a concentration of 10 micrograms/ml. The highest expansion was obtained on fibronectin, laminin and collagen type III, all three being statistically significantly greater than on the uncoated control surface (0.002 greater than p greater than 0.0001). Collagens types I and IV and a high molecular weight fragment mixture of type IV (IV-F, consisting of 75, 120 and 140 kD fragments) elicited approximately similar expansion rates, significantly higher than the control (0.02 greater than p greater than 0.003), although significantly lower (approximately 15%) than collagen type III, fibronectin and laminin (p less than 0.001). The high monolayer expansion on collagen type III is surprising, as it is a relatively minor biosynthetic product of the endothelial cell. It could, however, be of significance in wound healing, in which endothelial cells come into contact with this interstitial collagen. In addition, the similar results obtained with collagens IV and IV-F indicate that expansion of the endothelial monolayer is not dependent on the integrity of the tetrameric structure of type-IV collagen.

Basement Membrane↗
PubMed1990

Chicken gizzard 5'-nucleotidase is a receptor for the extracellular matrix component fibronectin.

The smooth muscle cells of chicken gizzard harbor the ectoenzyme 5'-nucleotidase. The purified enzyme was reconstituted into 3H-labeled proteoliposomes which were used as a model to study the association of a membrane protein with fibronectin. We demonstrated that the binding process between proteoliposomes and fibronectin has the qualities of a receptor-ligand interaction, i.e., is saturable and specific. In contrast to the association of fibronectin with integrins, the interaction with 5'-nucleotidase does not require divalent metal ions. Synthetic peptides containing the RGD-sequence or a monoclonal antibody interfering with binding of other receptors to the cell-binding domain of fibronectin did not abolish the interaction with 5'-nucleotidase. This indicates that the RGDS-sequence does not represent the major contact site for the AMPase and that the 5'-nucleotidase belongs to a separate class of fibronectin receptors with distinct properties as compared to the integrins.

5'-Nucleotidase↗