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Biomedical subjects

A Schwarz

Publications and source records attributed to A Schwarz.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Condition of patients after surgical wisdom tooth extraction under general anesthesia with different premedication variants--a prospective study based on a post-anesthesia questionnaire].

Evaluation of the modified "postanaesthesiological questionnaire" pointed to a subtle influencing of the condition of patients who had undergone 3rd molar surgery in general anaesthesia by using different premedication variants: "Atropine, Pethidine and Midazolam" (group A) and "Atropine, Midazolam and S-Ketamin" (group B). The combination in group B seems to be more suitable. On the one hand, a lower incidence of unwanted side-effects was found and, on the other hand, remarkable positive effects were observed. Of particular significance with this combination was also the more effective suppression of postoperative pain. The Propofol-supplemented general anaesthesia prepared in this way and administered using a nasal intubation technique found the full approval of the patients. Postoperative pain therapy was effective and also inexpensive, costing just 8.20 DM per patient, according to current prices calculated by Magdeburg University Hospital.

Adult↗
PubMed2000

Asymmetry pays: visual lateralization improves discrimination success in pigeons.

Functional cerebral asymmetries, once thought to be exclusively human, are now accepted to be a widespread principle of brain organization in vertebrates [1]. The prevalence of lateralization makes it likely that it has some major advantage. Until now, however, conclusive evidence has been lacking. To analyze the relation between the extent of cerebral asymmetry and the degree of performance in visual foraging, we studied grain-grit discrimination success in pigeons, a species with a left hemisphere dominance for visual object processing [2,3]. The birds performed the task under left-eye, right-eye or binocular seeing conditions. In most animals, right-eye seeing was superior to left-eye seeing performance, and binocular performance was higher than each monocular level. The absolute difference between left- and right-eye levels was defined as a measure for the degree of visual asymmetry. Animals with higher asymmetries were more successful in discriminating grain from grit under binocular conditions. This shows that an increase in visual asymmetry enhances success in visually guided foraging. Possibly, asymmetries of the pigeon's visual system increase the computational speed of object recognition processes by concentrating them into one hemisphere while preventing the other side of the brain from initiating conflicting search sequences of its own.

Animals↗
PubMed2000

Delayed onset of late movement-related cortical potentials and abnormal response to lorazepam in catatonia.

Catatonia is a psychomotor syndrome with an inability to execute and terminate movements completely, leading consecutively to akinesia and posturing, which both respond almost immediately to benzodiazepines, i.e. gaba-potentiators like lorazepam. However, pathophysiological mechanisms of cortical motor and gaba-ergic dysfunction remain unclear. We therefore investigated movement-related cortical potentials (MRPs) and movement kinematics during a motor task before and after lorazepam. Ten akinetic catatonic patients were compared with 10 psychiatric (similar age, sex, medication, and underlying psychiatric disease but without catatonic syndrome) and 20 healthy controls. MRPs from frontal (F), central (C), and parietal (P) sites were recorded to obtain measures of early and late readiness potential and movement potential. Kinematic measures included parameters for amplitude of movements, peak velocity, average duration of movements, elevation angle, and angle velocity. The motor task consisted in self-initiated extension of the right index finger. All catatonic and psychiatric control patients received intravenous lorazepam (1mg), whereas healthy controls were subjected to a placebo-controlled (10 received lorazepam, 10 received placebo) double-blind study design.Catatonics showed a significantly delayed onset of late readiness and movement potential in central electrodes (Cz, C3) compared with psychiatric and healthy controls. This delayed onset correlated significantly with catatonic motor symptoms and movement duration. Lorazepam led to significantly stronger delays in onset of late readiness potential in left fronto-parietal (F3, C3, P3) electrodes in catatonic patients than in psychiatric and healthy controls. It is concluded that delayed latencies in late MRP components in catatonic patients may reflect their inability to execute and terminate movements completely. Differential and stronger response to lorazepam in catatonia suggests dysfunction in inhibitory control of cortical motor function with increased gaba-ergic sensitivity.

Adult↗
PubMed2000

Evidence for functional relevance of CTLA-4 in ultraviolet-radiation-induced tolerance.

Hapten sensitization through UV-exposed skin induces hapten-specific tolerance that can be adoptively transferred by injecting T lymphocytes into naive recipients. The exact phenotype of T cells responsible for inhibiting the immune response and their mode of action remain unclear. Evidence exists that CTLA-4 negatively regulates T cell activation. We addressed whether CTLA-4 is involved in the transfer of UV-induced tolerance. Injection of lymph node cells from mice that were sensitized with dinitrofluorobenzene (DNFB) through UV-irradiated skin inhibited induction of contact hypersensitivity against DNFB in the recipient animals. When CTLA-4+ cells were depleted, transfer of suppression was lost. Likewise, significantly fewer lymphocytes enriched for CTLA-4+ cells were necessary to transfer suppression than unfractionated cells. Expression of CTLA-4 appears to be functionally relevant, since in vivo injection of a blocking anti-CTLA-4 Ab was able to break UV-induced tolerance and inhibited transfer of suppression. Upon stimulation with dendritic cells in the presence of the water-soluble DNFB analogue, DNBS, CTLA-4+ T cells from DNFB-tolerized mice secreted high levels of IL-10, TGF-beta, and IFN-gamma; low levels of IL-2; and no IL-4, resembling the cytokine pattern of T regulatory 1 cells. Ab blocking of CTLA-4 resulted in inhibition of IL-10 release. Accordingly, transfer of tolerance was not observed when recipients were treated with an anti-IL-10 Ab. Hence we propose that T cells, possibly of the T regulatory 1 type, transfer UV-mediated suppression through the release of IL-10. Activation of CTLA-4 appears to be important in this process.

Abatacept↗
PubMed2000

[Stage-adapted reconstruction of the stomach after gastrectomy].

The only realistic chance of a cure for cancer of the stomach is gastrectomy with a wide margin of clearance. The question as to what constitutes the ideal reconstruction of a substitute stomach, however, remains unanswered. A number of prospective randomized studies show that patients operated on in curative intent and with a good long-term prognosis, should be given a substitute stomach in the form of a pouch constructed from small bowel, with restoration of duodenal passage. On account of the shorter operating time, patients receiving palliative surgery should be treated with a simple oesophagojejunostomy without such a small-bowel pouch substitute stomach.

Anastomosis, Roux-en-Y↗
PubMed2000

An IgE-dependent secretory response of mast cells can be induced by a glycosphingolipid-specific monoclonal antibody.

The signal transduction pathway of the type 1 Fcepsilon receptor (FcepsilonRI) has been proposed to be spatially constrained to plasma membrane microdomains enriched in glycosphingolipids and cholesterol. These domains are proposed to serve as platforms that enhance the efficiency of the antigen-receptor stimulus-response coupling process. Here we describe a monoclonal antibody (mAb) designated 2B5, raised by immunizing mice with rat mucosal-type mast cell (line RBL-2H3) membranes, which binds to glycosphingolipids and causes a dose-dependent secretory response of these cells. This secretory response to mAb 2B5 requires binding of IgE to the FcepsilonRI on these cells, although direct interactions between IgE and mAb 2B5 are excluded. The bound IgE- or FcepsilonRI-specific mAb did not affect binding of mAb 2B5 or its Fab fragments to the RBL-2H3 cells and only a limited interference with the binding of IgE to the FcepsilonRI by mAb 2B5 was observed. Binding of mAb 2B5 to the RBL-2H3 cells induced a distribution of fluorescently labeled IgE similar to that produced by antigen-induced aggregation of the IgE-FcepsilonRI. Thus we suggest that mAb 2B5 binds to cell surface glycosphingolipids that are probably associated with the FcepsilonRI-IgE complexes and causes their aggregation, thereby initiating the cascade leading to the cell's secretory response.

Animals↗
PubMed2000

[Nuclear medicine diagnosis in diseases of the central nervous system].

Positron-emission tomography (PET) and single photon emission computed tomography (SPECT) can be used to visualize and quantify cerebral perfusion, glucose consumption, neurotransmission, and amino acid uptake. These techniques are clearly superior to conventional structural imaging techniques for several indications. This contribution describes the clinical role of PET and SPECT in clinical neurology.

Animals↗
PubMed2000

Anti-galactose-alpha(1,3) galactose antibody production in alpha1,3-galactosyltransferase gene knockout mice after xeno and allo transplantation.

Antibodies (Abs) that mediate the hyperacute rejection and acute vascular rejection/delayed xenograft rejection of pig organs in humans and Old World primates are predominantly directed at a single carbohydrate epitope, galactose-alpha1,3-galactose (alpha1,3Gal). The T-cell dependence of elicited anti-alpha1,3Gal Ab responses in humans and Old World primates is controversial. In this study we have characterized anti-alpha1,3Gal Ab production in mice with disrupted alpha1,3-galactosyltransferase genes (GT-Ko mice) and determined the T-cell dependence of anti-alpha1,3Gal Ab responses, following xenograft and allograft transplantation. GT-Ko mice produce natural anti-alpha1,3Gal IgM and IgG in an age-dependent manner, however, these Abs could not elicit hyperacute rejection nor affect the rate of cardiac xenograft (3-5 days) or allograft rejection (7-9 days). Transplantation of xenogeneic Lewis rats hearts elicited modest anti-alpha1,3Gal Ab, but vigorous xenoAb responses. The anti-alpha1,3Gal Ab response was restricted to the IgM and IgG3 subclass while the xenoAb response comprised IgM and all four IgG subclasses. Transplantation of allogeneic C3H hearts elicited weak anti-alpha1,3Gal Ab responses that were primarily IgM, but vigorous alloAb responses. Despite the restriction of elicited anti-alpha 1,3Gal Ab responses to the IgM and IgG3 isotypes, these responses are T-cell dependent. The ability of allografts to elicit weak anti-alpha1,3Gal but strong allo-Ab responses, can be explained by the dependence of alpha1,3Gal-specific B cells on cognate help from T cells.

Age Factors↗
PubMed2000

[Promoting reading and spelling in children with computer programs].

OBJECTIVES AND METHODS: Sixteen students trained their reading and spelling skills with the computer programmes Budenberg 1 and 2 and the Comles Package for 1000 minutes over a one-month period. RESULTS: Following one month of computer training, reading test scores had improved for seven of the 16, and spelling test scores for three children whose basic performance had been poor. Three and a half months of school instruction later, the reading test scores had improved for nine children, while there was no effect upon the spelling scores for most of the students.

Child↗
PubMed2000

[Malacoplakia-like reaction in association with colorectal adenocarcinoma].

17 cases of malacoplakia in association with an adenocarcinoma of the colon or rectum are known. In this report we describe a new case of this rare combination. An 83-year-old comatose female patient was admitted in an emergency situation because of an incipient ileus. A carcinoma had been known for months, but the patient had previously rejected any diagnostic or therapeutic measures. A tumor (6 cm in diameter) in the upper rectum was removed. This tumor had caused an obstruction of the lumen and reached the serosa. Histologically, an adenocarcinoma with suppurations in the stroma was staged pT3, G2, pN0 (clinically pT4 because of the perforated colonic wall). PAS- and von-Kossa-positive Michaelis-Gutmann-bodies were found in macrophages. Ultrastructurally, they turned out to be circular shifted early stage calcifications. Any malacoplakia-like lesion in suspicious areas of the colonic wall should be followed up by further diagnostic measures, since it may indicate the presence of an adenocarcinoma.

Adenocarcinoma↗
PubMed2000

Autoantibodies against autonomic nervous tissues in type 2 diabetes mellitus: no association with cardiac autonomic dysfunction.

There is evidence that autoimmune factors contribute to the pathogenesis of cardiac autonomic dysfunction in Type 1 Diabetes mellitus (DM). To evaluate the presence of autoantibodies against autonomic nervous tissues in Type 2 DM, 127 patients were studied for complement-fixing sympathetic and parasympathetic ganglia (CF-SG and CF-PSG) autoantibodies with an indirect immunofluorescence technique. Five cardiac reflex tests were performed to investigate cardiac autonomic neuropathy. QTc interval was assessed in all patients. As a control group, 60 healthy non-diabetic subjects were also tested for CF-SG and CF-PSG autoantibodies. CF-SG autoantibodies were detected in 11 (9%) and CF-PSG autoantibodies were observed in 7 (6%) Type 2 DM patients, whereas in control subjects, the frequency was 1 (2%) and 0 (0%) respectively (ns vs. Type 2 DM patients). In Type 2 DM patients with cardiac autonomic neuropathy (n=31, 24%), CF-SG autoantibodies and CF-PSG autoantibodies were detected in 3 (10%) patients, respectively, compared to 8 (8%) and 4 (4%) in Type 2 DM patients without cardiac autonomic neuropathy (n=96, 76%, ns v. Type 2 DM with cardiac autonomic neuropathy). Both CF-SG autoantibodies and CF-PSG autoantibodies were observed in 2 (7%) Type 2 DM patients with cardiac autonomic neuropathy and 3 (3%) Type 2 DM patients without cardiac autonomic neuropathy. Type 2 DM patients with cardiac autonomic neuropathy demonstrated a longer QTc-interval (446+/-42 ms) than Type 2 DM patients without cardiac autonomic neuropathy (413+/-45 ms, p=0.0001). In Type 2 DM patients with a prolonged QTc-interval (>440 ms: n=29, 23%), 2 (7%) patients presented with CF-SG and 3 (10%) had CF-PSG autoantibodies. In Type 2 DM, CF-SG and CF-PSG autoantibodies are not frequently observed. The results do not give evidence, that immunological factors--like in Type 1 DM--play a role in the pathogenesis of cardiac autonomic dysfunction in Type 2 DM.

Autoantibodies↗
PubMed2000

ETA receptor blockade induces fibrosis of the clipped kidney in two-kidney-one-clip renovascular hypertensive rats.

BACKGROUND: In two kidney-one clip renovascular hypertension (2K1C), blood flow is reduced in the clipped kidney leading to ischaemia. The non-clipped kidney is characterized by increased shear stress. Circulating Ang II is elevated. All these factors are stimuli of the paracrine renal endothelin system. Indeed, we demonstrated an activation of the renal endothelin system in the 2K1C rat model. METHODS: We analysed the effects of chronic treatment with the ETA receptor antagonist BQ-123 on blood pressure, heart rate, plasma renin activity, and on the progression of glomerulosclerosis, interstitial fibrosis and vascular remodeling in the clipped and non-clipped kidney. RESULTS: Long-term treatment with BQ-123 led to a fibrotic atrophy of the clipped kidney characterized by a significantly reduced weight of the clipped kidney compared to the clipped kidney of the placebo-treated group. Computer-aided image analysis revealed a markedly enhanced interstitial fibrosis of these clipped kidneys after long-term ETA blockade. The effects of ETA receptor antagonists on the non-clipped kidney were less pronounced. Neither blood pressure nor plasma renin activity were significantly altered by BQ-123 treatment. CONCLUSIONS: The present study indicates that long-term blockade of the activated endothelin system in the clipped kidney of rats with renovascular hypertension using an ETA receptor antagonist led to a fibrotic atrophy of the clipped kidney.

Animals↗
PubMed2000

Activation of the hepatic endothelin-system in rats with biliary liver fibrosis.

Circulating plasma endothelin-1 (ET-1) is elevated in liver cirrhosis, in a disease-stage-dependent manner. However, ET-1 exerts its effects mainly via paracrine and autocrine pathways. Therefore, the aim of the present study was to analyze the hepatic endothelin (ET) system in liver cirrhosis resulting from bile duct obstruction (BDO). Wistar rats were subjected for 6 weeks to either sham operation (control) or BDO. Thereafter, hepatic ET-1 concentrations were elevated 7.2-fold in BDO compared to control (p <0.001), whereas big ET-1 was unchanged. The density of both ET receptor subtypes was upregulated in BDO (ETA: 7.4-fold and ETB: 4.9-fold vs control, p < 0.001, respectively). The affinity of both receptor subtypes was significantly reduced in BDO. In conclusion, our data demonstrated for the first time that the hepatic ET system in liver cirrhosis is characterized by a simultaneous upregulation of both ET-1 tissue concentration as well as the density of hepatic ETA- and ETB-receptors, suggesting a synergistic activation of the hepatic ET system in rats with BDO. The increased ET-1 tissue concentration is not a result of an altered big ET-1 synthesis in biliary liver fibrosis, suggesting an increased activity of endothelin-converting enzyme (ECE) in liver cirrhosis.

Animals↗
PubMed2000

Pulmonary fibrosis and chronic lung inflammation in ET-1 transgenic mice.

The pulmonary endothelin (ET) system has been implicated in the pathogenesis of chronic lung diseases such as pulmonary hypertension, asthma, chronic obstructive lung disease, idiopathic pulmonary fibrosis, and bronchiolitis obliterans. However, the etiologic role of ET-1 in these diseases has not yet been established. We recently demonstrated that ET-1 transgenic mice, generated using the human prepro-ET-1 expression cassette including the cis-acting transcriptional regulatory elements, had predominant transgene expression in lung, brain, and kidney. We used these mice in the present study to analyze the pathophysiologic consequences of long-term pulmonary overexpression of ET-1. We found that ET-1 overexpression in the lungs did not result in significant pulmonary hypertension, but did result in development of a progressive pulmonary fibrosis and recruitment of inflammatory cells (predominantly CD4-positive cells). Our study provides evidence that a long-term activated pulmonary ET system, without any other stimuli, produces chronic lymphocytic inflammation and lung fibrosis. This suggests that overexpression of ET-1 may be a central event in the pathogenesis of lung diseases associated with fibrosis and chronic inflammation, such as pulmonary fibrosis and bronchiolitis.

Animals↗