Biomedical subjects
Publications and source records attributed to H Richter.
A simple score for mobilisation of patients with deep venous thrombosis of the leg is proposed. By this score the significantly earlier mobilisation of patients with deep venous thrombosis is possible without risk.
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.
Three children with congenital clavicular pseudarthrosis are reported in this paper. Reference is made to indications for surgery and to the surgical approach.
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.
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.
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.
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.
Explore the source record for details and available documents.
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.
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.
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.
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.
In October 1987 voluntary screening for cholesterol war performed in a bank. After preceding information had been issued to the participants 25 ml blood were drawn on 4 days from 667 employees (48.9% males, 51.1% females) for determination of the blood lipids and other parameters. The mean age (range 19 to 60) was 39 +/- 9 years; 29.2% were smokers. The mean cholesterol level amounted to 212 mg/dl. According to age- and sex-related normal values 42% exhibited an increased risk, whereby the percentage was particularly high (55%) in the age group under 30 years.
A Dictyostelium discoideum repetitive element composed of long repeats of the codon (AAC) is found in developmentally regulated transcripts. The concentration of (AAC) sequences is low in mRNA from dormant spores and growing cells and increases markedly during spore germination and multicellular development. The sequence hybridizes to many different sized Dictyostelium DNA restriction fragments indicating that it is scattered throughout the genome. Four cDNA clones isolated contain (AAC) sequences in the deduced coding region. Interestingly, the (AAC)-rich sequences are present in all three reading frames in the deduced proteins, i.e., AAC (asparagine), ACA (threonine) and CAA (glutamine). Three of the clones contain only one of these in-frame so that the individual proteins carry either asparagine, threonine, or glutamine clusters, not mixtures. However, one clone is both glutamine- and asparagine-rich. The (AAC) portion of the transcripts are reiterated 300 times in the haploid genome while the other portions of the cDNAs represent single copy genes, whose sequences show no similarity other than the (AAC) repeats. The repeated sequence is similar to the opa or M sequence found in Drosophila melanogaster notch and homeo box genes and in fly developmentally regulated transcripts. The transcripts are present on polysomes suggesting that they are translated. Although the function of these repeats is unknown, long amino acid repeats are a characteristic feature of extracellular proteins of lower eukaryotes.
To further characterize colonic motility in the dog and to examine the effects of intraluminal contents, motor activity in conscious animals was recorded by perfused intraluminal catheters. Animals were studied first with the bowel intact and, later, the colon was fashioned into an isolated loop. In the fasting state, cycles of motility recurred approximately each 30 min. These consisted of sequences of phasic contractions (bursts) that migrated variable distances in either direction; stationary bursts were also recorded. The fasting patterns recorded from intact bowel and isolated loops were not different. Feeding increased colonic motility, and the mean periodicity of cyclic bursts was reduced significantly to approximately 20 min. Moreover, differences were observed between intact bowel and isolated loops in the postprandial period. Diversion of chyme from the colon significantly reduced the motor response to food, but only in the late (2-4 hr) postprandial period, when the less frequent, fasting cycle returned to the loops. Perfusion of isolated loops with chyme or saline reestablished the postprandial pattern seen in intact bowel. The results suggest that the volume, but not the composition, of luminal contents modify postprandial motility in the canine colon. Additional experiments confirmed that, in particular, volatile fatty acids were probably not important determinants of colonic motility in the dog.
Previous experiments (Hörmann, H. & Jelinić, V. (1980) Hoppe-Seyler's Z. Physiol. Chem. 361, 379-387) had shown that heparin promoted the binding of plasma fibronectin to peritoneal macrophages of guinea pigs. The present data reveal that this effect only takes place at higher fibronectin concentrations indicating cooperative processes, most likely association of fibronectin at the cell surface. An unspecific precipitation of fibronectin by heparin was prevented by calcium in the medium. The accumulation at the cell surface was inhibited by the following fibronectin fragments: N-terminal 30 kDa and 70 kDa containing a potential self-association site and a transamidase-reactive site; central 95 kDa which comprised a negatively charged region possibly involved in self-association as well as the so-called alternative cell-binding site, but was lacking the cell-binding Arg-Gly-Asp sequence; heparin-binding 37-kDa and 60-kDa fragments. All these domains and sites, therefore, were potentially important in the assembly process at the cell surface. A peptide comprising the sequence Arg-Gly-Asp was ineffective pointing against an involvement of this fibronectin cell-binding site in the overall process. Macrophages of older animals were less capable of accumulating fibronectin under the reaction conditions. Their capability was improved after preincubation with activated plasma transglutaminase (coagulation factor XIIIa) suggesting that a cell-attached transamidase might be important for the assembly process.
The use of seronegative blood products is important to prevent transfusion-associated cytomegalovirus infection in immunocompromised patients. We have screened 3,458 normal blood donors for CMV-IgG-antibodies with an ELISA to receive a panel of seronegative donors and to determine the antibody prevalence. 1,948 donors were seropositive. Female donors had higher antibody prevalence than males in each age range tested.
Explore the source record for details and available documents.