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Biomedical subjects

J Richter

Publications and source records attributed to J Richter.

At least 217 records · Page 12Linked to original sources
PubMed1994

The contraction state of myofibrils during global ischemia and after reperfusion following different forms of cardiac arrest. Correlation with metabolic parameters in the canine heart.

This study was undertaken in order to obtain information on the mode of reaction of the contractile apparatus after different forms of cardiac arrest, global ischemia and reperfusion, as well as on possible correlations between the contraction state of myofibrils and biochemical parameters. During the survival time, before the level of 3 mumol/gww creatine phosphate (CP) is reached, the contraction state shows only minor changes. During the revival time in which ATP tissue concentrations decay to 4 mumol/gww, the contribution of ATP, lactate, anorganic phosphate (Pa) and acidosis to the degree of relaxation depends on the method of cardiac arrest. At defined biochemical values, the degree of relaxation is comparable after aortic cross clamping (ACC) and St. Thomas perfusion, but significantly different compared to HTK perfusion. Thus, during the revival time, the relaxation of sarcomeres depends predominantly on the composition of the solutions used for cardiac arrest. The re-entry of contraction below 3 mumol/gww ATP is correlated with the ATP concentration, independent of the form of cardiac arrest. Reperfusion after HTK or St. Thomas cardioplegia and reversible ischemia leads to the focal formation of contraction bands, which do not occur during ischemia. This contraction state is significantly more pronounced after reperfusion of St. Thomas arrested hearts. Thus, the contraction state of myofibrils is influenced not only by alterations in metabolite concentrations, but also by the composition of cardioplegic solutions and by the characteristic conditions (sufficient energy, oxygen and Calcium) during reperfusion.

Adenosine Triphosphate↗
PubMed1994

Giant axonal neuropathy: a generalized disorder of intermediate filaments with longitudinal grooves in the hair.

Giant axonal neuropathy (GAN) is a generalized neurological disorder with accumulation of intermediate filaments in different cell populations. The hallmark are enormous axonal swellings containing densely packed neurofilaments. Clinical symptoms reported so far are mainly limited to the nervous system. We report on a four-year-old girl with clinical and sural nerve biopsy findings typical of GAN. In addition, scanning electron microscopy (SEM) showed longitudinal grooves in the hairs of our patient. This peculiarity so far has only been described in two other patients with GAN. Scanning electron microscopy of hairs therefore may serve as a method of screening in patients suspected of suffering from GAN.

Axons↗
PubMed1994

Minor physical anomalies in schizophrenia.

Using the Waldrop scale, minor physical anomalies were studied in 82 Caucasian subjects, including 41 schizophrenic and 8 bipolar adults, as well as 14 normal and 19 mentally retarded adults. An increased incidence of minor physical anomalies was found in the mentally retarded adults relative to the other groups. Consistent with previous studies, there was a trend for the total mean Waldrop score of the schizophrenic group to be higher than the mean score of the normal group. Minor physical anomalies (assessed by the Waldrop scale), however, appear to be of questionable utility in identifying "congenital" schizophrenia, at least as this putative subgroup of schizophrenia is currently conceptualized.

Adolescent↗
PubMed1994

Evaluation of lanthanide tracer methods in the study of mammalian pulmonary parenchyma and cardiac muscle by electron energy-loss spectroscopy.

Lanthanum (La) has widely been used as a tracer to study the integrity of plasma membranes. With conventional transmission electron microscopy (cTEM), the absence of electron scattering deposits from the cytoplasm has generally been assumed to reflect an intact cell membrane. However, the application of electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS) reveals that electron scattering deposits may be present which do not contain La. However, La could be detected in regions of pulmonary parenchyma and cardiac muscle that were devoid of electron scattering deposits. Therefore, to exclude misinterpretations based on cTEM the application of microanalytical techniques is strongly recommended for the study of the integrity of plasma membranes by means of La tracers. In addition, ESI and EELS are shown to distinguish between different tracers in simultaneous applications of La and terbium (Tb) which were used at the different faces of the pulmonary air-blood barrier. The analysis of the distribution of both tracers which form electron scattering deposits, indistinguishable by cTEM, may help us to understand the different functional significances of cellular alterations of both cellular borders of the barrier. As was shown for La, however, strictly controlled conditions are mandatory during the fixation procedure because an increase in the incubation time to more than 1 h in samples of pulmonary parenchyma may result in the occurrence of La deposits within the cytoplasm. In the absence of electron scattering deposits, the presence of La in glycogen granules and ribosome-containing areas of various types of alveolar septal cells even after 15 min incubation indicates that the absence of deposits does not necessarily correspond to the absence of the tracer.

Animals↗
PubMed1994

Scanning and transmission electron microscopy of human donor lungs: fine structure of the pulmonary parenchyma following preservation and ischemia.

In six cases of clinical single-lung transplantation, the contralateral donor lungs were studied by means of scanning (SEM) and transmission (TEM) electron microscopy. SEM and TEM revealed an overall good to excellent preservation of the pulmonary parenchyma. Since the donor double lung blocks, which were preserved by means of pulmonary arterial perfusion with modified Euro-Collins solution, were separated immediately prior to transplantation, transplanted and contralateral lungs had been subjected to identical influences. Comparing the arterial oxygenation achieved in the recipient 6 h after transplantation with the structural data of the corresponding contralateral donor lung, the degree of epithelial alterations appeared to be most important in determining postoperative lung function. Concerning the assessment of the quality of the alveolar epithelium, gradings performed independently by means of SEM and TEM yielded largely corresponding scores, while a significant shortcoming of SEM was the very limited access to the endothelial surface. Taking into account the relevance of epithelial injury in determining postoperative lung function, SEM can provide clinically relevant data more quickly than TEM. To quantify the fine structural alterations of human donor lungs, however, TEM-based morphometry is required.

Adolescent↗
PubMed1994

Electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS) of multilamellar bodies and multilamellar body-like structures in tannic acid-treated alveolar septal cells.

We used electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS) to compare multilamellar bodies (MLB) of Type II alveolar epithelial cells with MLB-like structures that are present in various alveolar septal cells after fixation with tannic acid. Despite their structural similarity in conventional transmission electron microscopy, the phosphorus signal recorded by both ESI and EELS was considerably higher in multilamellar bodies than in MLB-like structures. This indicates that they are different in chemical composition.

Animals↗
PubMed1994

Albumin in the saliva--a significant indicator of the effect of "outdoor schools".

In 234 children residing permanently in a region with a high level of atmospheric pollution indicators of salivary immunity were studied as criteria for assessing the efficacy of applied compensatory measures. In the saliva SlgA, IgM, IgG, lysozyme, and albumin were determined. A marked reduction of elevated albumin levels which are characteristics of irritation or even inflammation in the oral cavity or respiratory tract was found in children who in the winter season spent some time in an unpolluted rural area. Statistically significant changes in IgM levels were demonstrated in these children.

Air Pollution↗
PubMed1994

[Health promotion in the school--fiction or central responsibility of school medicine?].

The causes of the most common diseases are now well known. This knowledge makes it possible to prevent them. Child mortality has been drastically reduced during the present century due to the eradication of infectious diseases. This target was reached by means of general immunization programmes and health education of the entire population. Other diseases were eliminated by changes of nutrition habits (gout) and by active substitution of vitamins (rickets) or by administration of minerals (caries, goitre). Diseases that are responsible for man not attaining his genetic life-span can only be eradicated by changing the style of living. With transmission of modern medical experience it is practicable to promote health and to avoid diseases. It is therefore indispensable to organize early recognition of diseases in children and juveniles, to implement full immunization programmes and to promote health education programmes for children, parents and teachers. Health promotion programmes are only effective if they reach the young people of the entire population. This is only possible through the Public Health service. Health promotion in this sense is no longer a fiction but an all-time duty of school doctors. A basic prerequisite for this function is permanent postgraduate medical education of school doctors and constant cooperation between physicians and educationalists.

Adolescent↗
PubMed1994

[Long-term effects of breathing exercises and yoga in patients with bronchial asthma].

To compare the effects of breathing exercises (BE) or Yoga (Y) on the course of bronchial asthma we studied 36 subjects with a mild disease. The patients were randomly divided into 3 groups. 2 of them participated in a 3 weeks training program of BE or Y while the third group rested without any additional treatment (control group, C). At the end of the training period the patients were asked to practise BE or Y on their own. Drug therapy and lung function parameters before and after a beta 2-agonist metered dose inhaler (albuterol, ALB) were recorded prior to the training program and in 4 weeks intervals for 4 months thereafter. The response to the beta 2-agonist was documented continuously in 28 patients. The mental state of the patients was elucidated by questionnaires.--Prior to the study a significant effect of inhaled ALB on the FEV1 was shown without any significant between group differences. Both, BE and Y, caused a significant amelioration of the mental state but only the BE induced a significant improvement of lung function parameters compared to the individual baseline values. The FEV1 increased significantly by 356.3 +/- 146.2 ml (p < 0.05) and the VC by 225.0 +/- 65.5 ml (p < 0.01). These long-term changes were not significantly different from the actual response to ALB. BE decreased the RV significantly by 306.3 +/- 111.6 ml (p < 0.05), an effect significantly higher compared to the beta 2-agonist (p < 0.01). BE in combination with ALB caused an additive effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Sports fitness after functional conservative versus surgical treatment of acute Achilles tendon ruptures].

Acute Achilles tendon ruptures are mostly related to recreational activities. Therefore, these patients intend to return to sports as soon as possible with no functional deficiency. This is the first study, comparing functional results after functional treatment to those after surgery. According to sonographic examinations of the tendon gap, primary functional treatment with heel supported shoes or surgery were suggested. Between 2/1991 and 12/1992, 22 patients with acute Achilles tendon rupture were treated without operation (group 1) and in 10 patient the rupture was sutured (group 2). 6 months later, 27 patients underwent standardized clinical examination: one leg standing for one minute, measurement of the circumference of the calf. The actual activities were assigned to Tegner Activity Score. 19 patients had isokinetic cybex testing with 60 degrees/s. There were 3 re-ruptures in group 1 and no comparable complications in group 2. At this time, clinical examination and Tegner Activity Score showed no relevant differences. Force of flexion was 30.4% lowered in group 1 and 2.4% in group 2. Additional training of the calf muscles improved the results after 6 weeks in group 1. We concluded that individual management of acute Achilles tendon rupture is possible according to sonographic tendon gap. Functional treatment is effective, but the rate of re-ruptures has to be reduced by careful selection of patients (rupture gap < or = 2 mm, high cooperation).

Achilles Tendon↗
PubMed1994

[Quantification of myocardial tomography with thallium in coronary disease. Evaluation of the Cedars-Sinai technique].

OBJECTIVE: The aim of this study is to evaluate the contribution of the Cedars-Sinai quantification tomographic method (CS) in the diagnosis and localization of ischemic areas in coronary artery disease (CAD) and to optimize the threshold values proposed by CS. PATIENTS AND METHODS: Fifty patients with clinical suspicion of CAD performed a maximal stress test by cycloergometer; thallium myocardial tomographic images were obtained; applying the CS program afterwards. The sensitivity and specificity variations obtained by changing the criteria for extent of myocardial hypoperfusion (range 1% to 100%) were used to calculate the new thresholds (CS-I), using the results of coronariographic studies as a reference. The data determined by qualitative analysis were compared with that obtained by quantitative analysis by means of CS and CS-I using coronary angiography as the standard of reference. RESULTS: The coronary angiography showed coronary disease in 37 patients. The sensitivity for the diagnosis of CAD was superior using CS (97%) at the expense of low specificity (15%) which nevertheless improved with CS-I (54%). For the location of CAD, the visual analysis was statistically significant (p < 0.05) in the left anterior descending and right coronary arteries, CS being superior in the diagnosis of 3 vessel disease. CONCLUSIONS: The quantification of tomographic studies with thallium by means of CS needs a readjustment of the thresholds. The tested values (CS-I) improved the CS results, although they require prospective validation. Quantitative study permits the confirmation of visual findings, being a complementary method that can be rapidly and easily interpreted, although it is not recommended as a single technique for the diagnosis of coronary disease.

Adult↗
PubMed1994

[Clinical and sonographic meniscus diagnosis].

Clinical examination still plays an important role in diagnosing meniscal tears. The types of sensitive nerves in the knee joint are responsible for nonspecific pain, which is often correlated with too little specificity in meniscal tests. Ultrasound examination of meniscal structures of the knee joint has been debated extensively in recent years. Criticism of this noninvasive technique was due to small patient groups, improper technical and inaccurate manual standards. Since 1988 ultrasound of the tibial meniscus has become a standard technique in our Department of Orthopaedic Surgery with defined criteria of the intersecting plane and evaluation of ultrasound images. A prospective follow-up study during 6/1988 and 5/1993 including 1186 ultrasound examinations before arthroscopy, was performed. The sensitivity for ultrasound of the lateral meniscus was 58% and for the medial meniscus 83%. Specificity with 98% for the lateral and 90% for the medial meniscus was good. Sonographic detection of meniscal tears depends on the shape and location of meniscal tears. This has been shown by experimental studies in cadavers. A follow-up study including 113 knee joints was performed to prove the value of clinical and ultrasound examination in relation to arthroscopy. The sensitivity of sonography for medial meniscus was 81% and 40% for the lateral meniscus. Although the sensitivity of the clinical examination was 81% (medial) and 47% (lateral), the low specificity of 70% for meniscus tears indicated that it was because of false-positive clinical evaluation of meniscal disorders. In young patients with reflectory muscle spasm and those with acute trauma of the knee joint, clinical examination of the meniscal structures showed poor results. In these cases, too, ultrasound examination showed advantages. Ultrasound of the knee joint meniscus is noninvasive, reproducible and low cost. In cases of uncertain clinical results, ultrasound offers a good opportunity to visualize meniscal disorders.

Adolescent↗
PubMed1993

Molecular cloning of a P-type ATPase gene from the cyanobacterium Synechocystis sp. PCC 6803. Homology to eukaryotic Ca(2+)-ATPases.

With oligonucleotide primers derived from P-type ATPase genes of different sources, a part of Synechocystis sp. PCC 6803 genomic DNA was amplified and used as hybridization probe for the Synechocystis gene. A 4.7 kb HindIII fragment was cloned and sequenced; it contains the open reading frame of the E1E2-ATPase. The Synechocystis ATPase (named PMA1) consists of 915 amino acids with a M(r) of 98,902; it has ten putative transmembrane domains and contains the conserved regions a to j common to all P-type ATPases. Its amino acid sequence shows less than 20% identity to prokaryotic ATPases but about 30% identity to eukaryotic Ca(2+)-ATPases. An alignment to rat kidney and yeast Ca(2+)-ATPase protein sequences shows homology in stalk regions and transmembrane domains domains which are thought to be involved in calcium binding and transport; these three ATPases reveal very similar hydropathy plots and form a separate group in the phylogenetic tree of P-type ATPases. The results strongly support the assumption that PMA1 of Synechocystis is a calcium translocating ATPase, possibly involved in regulatory processes with calcium as second messenger.

Adenosine Triphosphatases↗
PubMed1993

Preservation of cardiac myocytes subjected to different preconditions: a comparative morphometric study of beating, fibrillating, and cardioplegically arrested canine hearts.

This study compares the ultrastructure of beating canine hearts with that of hearts subjected to different clinically common forms of cardiac arrest. The contraction state per test field was ascertained according to a specially developed classification. The volume density of myofibrils and the surface to volume ratio of mitochondria were used as parameters for cellular and mitochondrial swelling. Contraction bands were not found in any of the differently pretreated hearts. Following immersion fixation, contractions as well as over- and hypercontractions in beating, fibrillating, and St. Thomas-arrested hearts are significantly more pronounced than in HTK-arrested hearts. Cellular and mitochondrial volumes were similar in beating and fibrillating hearts. St. Thomas-perfusion significantly decreased cellular and mitochondrial volume compared to beating hearts, but these values were in the same range as in fibrillating hearts. Only HTK-solution actually led to a strong reduction of these compartments. Compared to immersion, perfusion fixation after coronary perfusion with cardioplegic solutions led to comparable cellular volumes, but significantly elevated the percentage of relaxed sarcomeres and significantly reduced mitochondrial swelling. The best structural preservation of myocytes was found after HTK-perfusion and perfusion fixation. Such ultrastructural quantitative and morphometrical parameters are powerful tools since results confirm that the degree of myocardial preservation depends on the method of cardiac arrest. This forms the basis for the choice of preconditions for subsequent ischemia. Furthermore, significant alterations of myocardial ultrastructure depend on a combination of the functional state of the heart, the method of cardioplegia, and the technique of fixation.

Animals↗
PubMed1993

Phorbol ester-induced degranulation in adherent human eosinophil granulocytes is dependent on CD11/CD18 leukocyte integrins.

Secretion of unique eosinophil granule constituents may play a role in allergic and parasitic reactions. Therefore we have investigated possible mechanisms for regulation of secretion in eosinophils. A hemolytic plaque assay and an enzyme-linked immunospot (ELISPOT) assay were developed for detection of secreted eosinophil cationic protein (ECP) from single adherent eosinophils. The protein kinase C activator phorbol 12-myristate 13-acetate (PMA) induced release of ECP in a dose-dependent fashion but 4-alpha-PMA, an analogue that does not activate protein kinase C, did not cause degranulation. Staurosporine and K252a, inhibitors of protein kinase C, decreased PMA-induced ECP secretion. Low concentrations of cytochalasin B enhanced PMA-induced secretion but high concentrations had an inhibitory effect. The calcium ionophores A23187 and ionomycin were weaker secretagogues than PMA. Tumor necrosis factor, granulocyte-macrophage colony-stimulating factor, interleukin-3, interleukin-5, N-formylmethionyl-leucyl-phenylalanine, and lipopolysaccharide caused little or no degranulation in adherent eosinophils. Preincubation of eosinophils with antibodies to CD18, the common beta chain of leukocyte adhesion proteins, resulted in inhibition of PMA-induced ECP release from adherent cells. 1,2-Bis(O-aminophenyl)-ethane-ethane-N,N,N',N'-tetraacetic acid (BAPTA), an agent that acts intracellularly by chelation of calcium, also inhibited PMA-mediated ECP release. In conclusion, PMA induces release of ECP from single adherent eosinophils and the effect appears to be mediated via protein kinase C and, in contrast to that in neutrophils, to be dependent on CD11/CD18 leukocyte integrins.

Antibodies↗
PubMed1993

Effects of angiotensin-converting enzyme inhibition on renal sodium handling after furosemide injection.

The goal of this study was to quantitate the effect of angiotensin-converting enzyme inhibition on renal sodium handling after furosemide injection. The study was carried out on low and normal salt intake to assess potential interaction with salt balance. Eighteen healthy normotensive volunteers were examined in a double placebo-controlled parallel group design. Subjects were randomly put on either low-salt (20 mmol/day) or normal-salt (110 mmol/day) diet. In either arm of the diet volunteers were first treated orally with placebo for 1 week and subsequently with 2.5 mg/day of the angiotensin-converting enzyme inhibitor cilazapril for another 1 week. Cumulative 24-h urinary sodium excretion was measured on the 6th day of the respective week after sham injection and on the 7th day after injection of 40 mg furosemide. Compared to pretreatment with placebo, pretreatment with cilazapril resulted in a higher cumulative sodium excretion after furosemide injection (day 7) than after the sham injection (day 6) on both salt intakes. The difference in natriuresis (cilazapril versus placebo) was evident 2 and 3 h after injection of furosemide. Neither the time of onset nor the magnitude of antinatriuresis were affected by cilazapril. Following furosemide angiotensin II increased significantly even after cilazapril pretreatment. Cilazapril tended to reduce urinary furosemide excretion. At any given urinary furosemide concentration, the increment in urinary sodium excretion was significantly greater with cilazapril irrespective of salt intake. The study shows that (a) cilazapril increases furosemide-induced natriuresis irrespective of salt intake, (b) antinatriuresis is not affected by cilazapril, and (c) angiotensin II levels rise after furosemide on cilazapril in therapeutic doses.

Adult↗