Biomedical subjects

R Richter

Publications and source records attributed to R Richter.

At least 37 records · Page 2Linked to original sources

PubMed2001

Binding of a model regulator of complement activation (RCA) to a biomaterial surface: surface-bound factor H inhibits complement activation.

The complement system is an important inflammatory mediator during procedures such as cardiopulmonary bypass and hemodialysis when blood is exposed to large areas of biomaterial surface. This contact between blood and the biomaterials of implants and extracorporeal circuits leads to an inflammatory response mediated by the complement system. The aim of this study was to assess the ability of a complement regulator (factor H) immobilised on a biomaterial surface to inhibit complement cascade mediated inflammatory responses. The cross-linker N-succinimidyl 3-(2-pyridyldithio) propionate was used to immobilise factor H on a model biomaterial surface without affecting the biological activity of the inhibitor. Binding of factor H was then characterised using quartz crystal microbalance-dissipation (QCM-D) and enzyme immunoassays for products of complement activation: bound C3 fragments and soluble C3a, sC5b-9, and C1s-C1INA. Immobilised factor H reduced the amount C3 fragments deposited on the biomaterial surface after incubation with serum, plasma. or whole blood. In addition, lower levels of soluble C3a and sC5b-9 were generated after incubation with whole blood. In summary, we have demonstrated that complement activation on a highly activating model surface can be inhibited by immobilised factor H and have defined prerequisites for the preparation of future biomaterial surfaces with immobilised regulators of complement activation.

Biocompatible Materials↗

PubMed2001

[Day clinic treatment in child and adolescent psychiatry].

OBJECTIVES: The history of day treatment in child and adolescent psychiatry in Germany is brief. Accordingly, day treatment programs deal primarily with programming, outcome studies and indications/contraindications. METHODS: This article reviews the English- and German-language literature between 1960 and 2000 relevant to the outcome of day treatment in child and adolescent psychiatry. Outcome studies are discussed. RESULTS: Outcome studies do not yet allow decisions about for whom day treatment does or does not exactly work. Nonetheless, evidence from the literature suggests that day treatment does work for many different disorders in child and adolescent psychiatry. The predictive value of parental involvement in therapy for outcome is supported by several studies. CONCLUSIONS: In addition to randomized controlled outcome studies, effectiveness studies of single day treatment programs are useful and should deliver the data on the kinds of children, treatment goals and results for which a program in a specific regional mental health care system is effective.

Adolescent↗

PubMed2001

[Patients' need for information before surgery].

Frequently, prior to surgery, patients are provided with information in order to meet legal and hospital requirements, but without taking their psychological needs into consideration. In order to learn how to improve this situation, the present study was performed. By means of a semi-structured interview including a newly constructed card system, that avoids giving patients undemanded and possibly harmful implicit information, the need for information of 60 patients before hip- or knee-replacement surgery were investigated in great detail. The results show that 83.3% of the patients want to be prepared by the surgeon, preferably by means of an oral communication (75.0%). Most frequently the day when decision for surgery is made and the day of hospitalization were preferred as point of time for preparation (30% each). Patients were more interested in information about the operation and recovery (43.3% each) than about risks (33.3%). Only 11.7% wanted to get psychological preparation prior to surgery. We conclude that coming into contact and establishing a trustful relationship with the surgeon who does the operation is the most crucial need of surgical patients. He should give presurgical information according to the patient's needs, which often do not focus on the risks, as legal regulations do. By providing psychological preparation for the small number of patients in need, psychological specialists may contribute to improve satisfaction and outcome of surgical patients.

Adult↗

PubMed2000

Posttranslationally processed forms of the human chemokine HCC-1.

HCC-1 is the only CC-chemokine known so far which circulates in nanomolar concentrations in human plasma. Its physiological function is not well defined. Posttranslational processing of HCC-1 was shown to modulate its biological properties. In this study several different processed forms of HCC-1 were isolated. Western blot analysis of human plasma extracts revealed a HCC-1 immunoreactive double band at 8-10 kDa indicating the presence of two distinct HCC-1 peptides. These peptides were isolated from a peptide library of human blood filtrate and represent predominantly HCC-1 (1-74) and glycosylated HCC-1 (1-74). Glycosylated HCC-1 exhibits a molecular mass of 9621 Da due to O-glycosylation at position 7 (Ser-7) with two N-acetylneuraminic acids and the disaccharide N-acetylgalactosamine galactose. Furthermore N-terminally truncated HCC-1 (3-74) and HCC-1 (4-74) were identified in the peptide library. In hemofiltrate approximately 3% of total HCC-1 represents HCC-1 (3-74) and approximately 1% represents HCC-1 (4-74) whereas the major products are nonglycosylated HCC-1 (1-74) and glycosylated HCC-1 (1-74). Our data imply that HCC-1 (1-74), HCC-1 (3-74), HCC-1 (4-74) and glycosylated HCC-1 (1-74) circulate in human blood. The N-terminal processing and modification of HCC-1 might be of importance in displaying its full biological activity.

Amino Acid Sequence↗

PubMed2000

Radiative and relativistic effects in the decay of highly excited states in helium

A recent experimental study [J.-E. Rubensson et al., Phys. Rev. Lett. 83, 947 (1999)] measured a significant fluorescence yield of the He( 2lnl(')) photoexcited resonances, showing major qualitative differences from nonrelativistic predictions. We present a further theoretical study of these states, and perform R-matrix multichannel quantum defect theory calculations to extract fluorescence and ionization cross sections. These theoretical results are in excellent agreement with newer, higher-resolution measurements. Radiative and spin-orbit effects are quantified and shown to play an important role in the overall characterization of highly excited states.

Journal Article↗

PubMed2000

[Psychotherapeutic and psychosocial therapy in general practice. Results of demonstration project on quality management in psychosocial primary care].

Since 1987, psychosocial primary care (PPC) provided by General Practitioners, are reimbursed by German health insurances. The aim of the psychosocial primary care is to improve recognition and treatment of mental disorders in the primary care sector. As a part of a eight-center national demonstration program on quality management in the outpatient services, General Practitioners (n = 191) from 5 regions participated in the study. 1341 treatment episodes of patients with predominately psychosocial strain were documented. Differences between psychosocial strain, treatment and outcome were determined by analyses of variance. Men and patients beyond the age of 65 were underrepresented. Psychosocial treatments were offered more often to those patients, who had the highest level of anxiety and depression. Patients with physical illness, with pain and without psychological attribution to the illness belief were offered less psychosocial interventions and reached a worse outcome. The study outcome helps to improve training programs as to recognition and treatment of psychosocial problems in primary care. Male and generally elderly patients with somatic symptoms and lack of psychological attribution need a special psychosocial intervention to improve the outcome.

Adult↗

PubMed2000

Wave number of maximal growth in viscous magnetic fluids of arbitrary depth

An analytical method within the frame of linear stability theory is presented for the normal field instability in magnetic fluids. It allows us to calculate the maximal growth rate and the corresponding wave number for any combination of thickness and viscosity of the fluid. Applying this method to magnetic fluids of finite depth, these results are quantitatively compared to the wave number of the transient pattern observed experimentally after a jumplike increase of the field. The wave number grows linearly with increasing induction where the theoretical and the experimental data agree well. Thereby, a long-standing controversy about the behavior of the wave number above the critical magnetic field is tackled.

Journal Article↗

PubMed2000

[Primary psychosomatic management in general practice. Results of a German nationwide demonstration project of quality assurance].

In the frame of a national demonstration program, psychosocial care of patients with psychological and psychosomatic problems were assessed. General practitioners (n = 191) from six regions participated in the study. 1341 treatment episodes of patients with predominately psychosocial symptoms were documented. Anxiety (62%), depression (51%) and marital/family conflicts (44%) were the most frequent symptoms. Somatic treatment and psychosocial intervention were offered equally. Patients with psychosocial treatment achieved better results. Partners and family members were rarely integrated into therapy. The procedures employed to improve outcome were quality circles, family-orientated case conferences, consultation services and collaborative groups.

Combined Modality Therapy↗

PubMed1999

Proteolytic cleavage of glucagon-like peptide-1 by pancreatic beta cells and by fetal calf serum analyzed by mass spectrometry.

Fetal calf serum and a beta-cell line exhibit a proteolytic activity essential for the biological function of glucagon-like peptide-1 (GLP-1). This process of cleavage was investigated using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). To generate processing products, GLP-1 was subjected to rat insulinoma m5F (RINm5F) cell cultures or to fetal calf serum (FCS). For detection of processing products, a standardized extraction method including ion-exchange batch extraction, ultrafiltration, gel filtration, and reversed-phase chromatography was used. The RP fractions were analyzed by MALDI-TOF-MS. Processed proteolytic products were detected by comparing the resulting mass spectra of cell media or FCS after 2 h incubation with GLP-1 (7-36) amide with these of 2 h controls. To perform the comparison of the resulting mass spectra, software (MASSSPECANALYST) based on Microcal Software, Origins C-like language LABTALK was developed. GLP-1 fragments were purified by RP-HPLC, and characterized by sequence analysis. As insulin is the major secretory product of beta cells depending on GLP-1 stimulation, the insulin and insulin fragments of the cell culture supernatants were also analyzed by this method.

Amino Acid Sequence↗

PubMed1999

Composition of the peptide fraction in human blood plasma: database of circulating human peptides.

A database was established from human hemofiltrate (HF) that consisted of a mass database and a sequence database, with the aim of analyzing the composition of the peptide fraction in human blood. To establish a mass database, all 480 fractions of a peptide bank generated from HF were analyzed by MALDI-TOF mass spectrometry. Using this method, over 20000 molecular masses representing native, circulating peptides were detected. Estimation of repeatedly detected masses suggests that approximately 5000 different peptides were recorded. More than 95% of the detected masses are smaller than 15000, indicating that HF predominantly contains peptides. The sequence database contains over 340 entries from 75 different protein and peptide precursors. 55% of the entries are fragments from plasma proteins (fibrinogen A 13%, albumin 10%, beta2-microglobulin 8.5%, cystatin C 7%, and fibrinogen B 6%). Seven percent of the entries represent peptide hormones, growth factors and cytokines. Thirty-three percent belong to protein families such as complement factors, enzymes, enzyme inhibitors and transport proteins. Five percent represent novel peptides of which some show homology to known peptide and protein families. The coexistence of processed peptide fragments, biologically active peptides and peptide precursors suggests that HF reflects the peptide composition of plasma. Interestingly, protein modules such as EGF domains (meprin Aalpha-fragments), somatomedin-B domains (vitronectin fragments), thyroglobulin domains (insulin like growth factor-binding proteins), and Kazal-type inhibitor domains were identified. Alignment of sequenced fragments to their precursor proteins and the analysis of their cleavage sites revealed that there are different processing pathways of plasma proteins in vivo.

Amino Acid Sequence↗

PubMed1999

Efficacy and safety of propiverine in SCI-patients suffering from detrusor hyperreflexia--a double-blind, placebo-controlled clinical trial.

AIMS OF THE STUDY: The aim of this double-blind, randomised, prospective, multicentre trial was to evaluate the efficacy of propiverine in patients suffering from detrusor hyperreflexia caused by spinal cord injury in comparison to placebo. STUDY DESIGN: The treatment period of 14 days comprised visits at baseline (V1) and after 14 days treatment (V2). Fifteen mg propiverine t.i.d. or placebo t.i.d. were administered as medication. The following efficacy parameters were adopted: the urodynamic parameters maximal cystometric bladder capacity, bladder volume on onset of the first as well as duration and amplitude of the maximum detrusor contraction, bladder compliance and residual urine, and subjective assessment of efficacy by physicians. For the evaluation of the safety of propiverine the incidence rate of adverse events by directly questioning as well as laboratory parameters were investigated. For biometrical evaluation t-test for independent groups was applied. RESULTS: One hundred and thirteen patients were investigated. The maximal cystometric bladder capacity increased significantly in the propiverine group, on average by 104 ml (V1: 262+/-132 ml. V2: 366+/-143 ml, P<0.001). The changes in bladder capacity during the first contraction and the maximum detrusor contraction in the verum group were both statistically significant. The bladder compliance documented a more pronounced increase under propiverine in comparison to placebo. Residual urine increased by 37+/-71 ml in the propiverine group, significantly more than in the placebo group (P=0.01). Sixty-three per cent of the patients expressed subjectively an improvement under propiverine in comparison with 23% of the placebo group. Expected anticholinergic adverse events occurred: dryness of the mouth (37% in the verum and 8% in the placebo group), accommodation disorders (28% and 2% respectively). Nausea, constipation, headache, dizziness, tiredness and palpitations were reported in almost comparable incidence rates between 3 and 13% in both treatment groups. Eight drop-outs were registered in the propiverine group (five due to adverse events) and three in the placebo group (one due to adverse events). The laboratory parameters revealed no changes. CONCLUSION: Propiverine proved its efficacy in detrusor hyperreflexia with regard to the urodynamic parameters of the maximal cystometric bladder capacity and detrusor contractility. Anticholinergic adverse events such as dryness of the mouth and accommodation disorders were considered being tolerable. The increase in residual urine reflects the therapeutically desired effect of detrusor relaxation because the majority of patients normally practise intermittent catheterisation for bladder emptying.

Adult↗

PubMed1999

Cyanophycinase, a peptidase degrading the cyanobacterial reserve material multi-L-arginyl-poly-L-aspartic acid (cyanophycin): molecular cloning of the gene of Synechocystis sp. PCC 6803, expression in Escherichia coli, and biochemical characterization of the purified enzyme.

The branched polypeptide multi-L-arginyl-poly-L-aspartic acid, also called cyanophycin, is a water-insoluble reserve material of cyanobacteria. The polymer is degraded by a specific hydrolytic enzyme called cyanophycinase. By heterologous expression in Escherichia coli, a gene encoding cyanophycinase has been identified in the sequenced genome of Synechocystis sp. PCC 6803. The gene, designated cphB, codes for a protein of 29.4 kDa. The high level of expression of active cyanophycinase in E. coli from the Synechocystis gene allowed for its purification to electrophoretic homogeneity. The enzyme, which appears to be specific for cyanophycin, hydrolysed the polymer to a dipeptide consisting of aspartic acid and arginine. Based on inhibitor sensitivity and primary sequence, cyanophycinase appears to be a serine-type exopeptidase related to dipeptidase E [Conlin, C.A., Haakensson, K., Liljas, A. & Miller, C.G. (1994) J. Bacteriol. 176, 166-172].

Amino Acid Sequence↗

PubMed1999

Effects of dobutamine on hemodynamics and left ventricular performance after cardiopulmonary bypass in cardiac surgical patients.

BACKGROUND: Dobutamine is commonly used to improve ventricular performance after cardiopulmonary bypass. The authors determined the effect of dobutamine on hemodynamics and left ventricular performance immediately after cardiopulmonary bypass in patients undergoing coronary artery bypass graft surgery. METHODS: One hundred patients received sequential 3-min infusions of dobutamine at 0-40 microg x kg(-1) x min(-1) immediately after cardiopulmonary bypass. Ten additional patients who received no dobutamine served as controls. Hemodynamics and left ventricular performance (fractional area change by transesophageal echocardiography, stroke volume index, and thermodilution cardiac index) were measured. Mixed-effects modeling accounted for repeated-measures data and interindividual differences and allowed for potential effects of covariates. RESULTS: Heart rate increased in a dose-dependent manner. The slope of HR versus dobutamine dose was steeper in individuals in whom peak dobutamine dose was not reached compared with that in the remaining individuals; slope decreased 2.71 +/- 0.68% per year of age. Dobutamine affected blood pressure minimally, but slightly decreased pulmonary capillary wedge pressure and central venous pressure. Systemic vascular resistance initially increased with dobutamine 10 microg x kg(-1) x min(-1) and remained constant with larger doses. Dobutamine produced a dose-dependent increase in left ventricular performance, primarily by increasing heart rate, because stroke volume index decreased with dobutamine dose. CONCLUSION: Our results suggest that the response to graded dobutamine infusion in the post-cardiopulmonary bypass period differs from that previously reported. After cardiopulmonary bypass, the dominant mechanism by which dobutamine improves left ventricular performance is by increasing heart rate. Dobutamine affects blood pressure minimally.

Aged↗

PubMed1999

Image analysis of implanted rigid and foldable intraocular lenses in human eyes using Scheimpflug photography.

We evaluated the quality of imaging posterior chamber intraocular lenses (PC IOL) by Scheimpflug photography. We took photographs of 190 rigid or foldable PC IOLs using the Scheimpflug system EAS-1000 from Nidek and provided digital image analysis. We found a good imaging of PC IOLs and the cristalline lens capsule, data obtained by digital image analysis were reliable and reproducible and Scheimpflug photography could be demonstrated as a sensitive tool to show any irregularities of IOL material. Thus, we found in foldable IOLs 'glistenings', which did not have any influence on functional results and we could distinguish them from lens damage. We propose to use Scheimpflug tests regularly for the examination of implanted new types of IOLs.

Humans↗

PubMed1999

Psychosocial care by general practitioners--where are the problems? Results of a demonstration project on quality management in psychosocial primary care.

OBJECTIVE: Since 1987, psychosocial services have been a part of the primary care setting in Germany. In the framework of an eight-center national demonstration program, problems in the diagnosis and therapy of psychosocial problems and psychosomatic disorders were assessed. Methods to improve quality were also implemented. METHOD: General practitioners (n = 191) from six regions participated in the study. One thousand three hundred and forty-one treatment episodes of patients with predominantly psychosocial symptoms were documented. Differences between psychosocial strain, treatment, and outcome were determined by analyses of variance. RESULTS: Anxiety (62%), depression (51%), and marital/family conflicts (44%) were the most frequent symptoms. Psychosocial treatment was offered more often to those patients who had the highest level of anxiety and depression. Patients with pain and without a psychological attribution to their illnesses were offered less psychosocial treatment and suffered worse results. Partners and family members were rarely integrated into therapy. The procedures employed to improve outcome were quality circles, family-oriented case conferences, consultation services, and collaborative groups. CONCLUSIONS: These initial results are promising. A process of internal quality management has been initiated. Some of the physicians still resist documenting the data. Patients with somatic symptoms without psychological attribution may need special psychosocial interventions to improve their outcomes.

Adolescent↗

PubMed1999

[Brief report of the working group OPD-CA (children and adolescents) Axis III: conflict].

Conflict according to the OPD is understood as a lasting and unconscious inner conflict, which should be described on the background of the child's or adolescent's developmental state. In accordance with the adult OPD the following seven conflicts can be differentiated: Dependence versus autonomy, submission versus control, desire for care versus autarchy, conflicts of self-value (narcissistic conflicts, self-value versus object-value), conflicts of loyalty (guilt conflicts, egoistic versus pro-social tendencies), oedipal sexual conflicts, identity conflicts (identity versus dissonance). These conflicts have been operationalized for 6 domain of daily living--family, peers, kindergarten/school, property, play and illness--for the developmental phases (2-5, 6-11, and older than 12 years) separately.

Adolescent↗

PubMed1998

Molecular characterization of cyanophycin synthetase, the enzyme catalyzing the biosynthesis of the cyanobacterial reserve material multi-L-arginyl-poly-L-aspartate (cyanophycin).

Cyanophycin (multi-L-arginyl-poly-L-aspartate), a water-insoluble reserve polymer of cyanobacteria, is a product of nonribosomal peptide synthesis. The purification of cyanophycin synthetase of the cyanobacterium Anabaena variabilis is described. In sodium dodecylsulfate/polyacrylamide gel electrophoresis, the enzyme preparation shows one band with an apparent molecular mass of 100 kDa. The native enzyme has an apparent molecular mass of approximately 230 kDa, as determined by size-exclusion chromatography, suggesting that the active form is a homodimer. During catalysis, ATP is converted to ADP. The gene coding for cyanophycin synthetase has been identified in the sequenced genome of Synechocystis sp. PCC 6803. The C-terminal 60% of the deduced amino acid sequence of cyanophycin synthetase show sequence similarity to enzymes of the superfamily of ligases involved in the biosynthesis of murein and of folyl-poly(gamma-glutamate). Cells of Escherichia coli harbouring the gene on a plasmid express active synthetase and accumulate cyanophycin-like material. The results prove that a single enzyme catalyzes the de novo synthesis of cyanophycin.

Adenosine Triphosphate↗

PubMed1998

Urodilatin, a natriuretic peptide with clinical implications.

Natriuretic peptides (NP) constitute hormonal systems of great clinical impact. This report deals with Urodilatin (URO), a renal natriuretic peptide type A. From the gene of NP type A, a message for the preprohormone is transcribed in heart and kidney. The cardiac prohormone CDD/ANP-1-126 is synthesized in the heart atrium and processed during exocytosis forming the circulating hormone CDD/ANP-99-126. URO (CDD/ANP 95-126) is a product from the same gene, but differentially processed in the kidney and detected only in urine. Physiologically, URO acts in a paracrine fashion. After release from distal tubular kidney cells into the tubular lumen, URO binds to luminal receptors (NPR-A) in the collecting duct resulting in a cGMP-dependent signal transduction. cGMP generation is followed by an interaction with the amiloriode-sensitive sodium channel which induces diuresis and natriuresis. In this way, URO physiologically regulates fluid balance and sodium homeostasis. Moreover, URO excretion and natriuresis are in turn dependent on several physiological states, such as directly by sodium homeostasis. Pharmacologically, URO at low dose administered intravenously shows a strong diuretic and natriuretic effect and a low hypotensive effect. Renal, pulmonary, and cardiovascular effects evoked by pharmacological doses indicate that URO is a putative drug for several related diseases. Clinical trials show promising results for various clinical indications. However, the reduction in hemodialysis/hemofiltration in patients suffering from ARF following heart and liver transplantation, derived from preliminary trials recruiting a small number of patients, was not confirmed by a multicenter phase II study. In contrast, data for the prophylactic use of URO in this clinical setting suggest a better outcome for the patients. Furthermore, treatment of asthmatic patients showed a convincingly beneficial effect of URO on pulmonary function. Patients with congestive heart failure may also profit from URO treatment, as it increases stroke volume and PCWP. Moreover, preliminary results from recent studies indicate that URO may also be effective in patients suffering from hepato-renal syndrome.

Acute Kidney Injury↗