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Biomedical subjects

E Nagel

Publications and source records attributed to E Nagel.

At least 73 records · Page 4Linked to original sources
PubMed1999

Selection of phage-displayed anti-guinea pig C5 or C5a antibodies and their application in xenotransplantation.

Xenogeneic liver transplantation in the discordant guinea pig (gp) to rat model results in hyperacute rejection within a few minutes, which is due to activation of the complement system. Currently no antibodies against gp complement factors are available, which allow activation of the gp complement system in serum or complement deposition in tissue to be detected. To close this gap, we started developing single chain Fvs (scFvs) against gpC5 and gpC5a. We generated a combinatorial library of scFv antibodies comprising the variable heavy and light chain repertoire from mice immunized with gpC5. Out of this library we selected several antibodies against gpC5 and C5a after four and six rounds of biopanning, respectively. Selected gpC5-specific scFvs were purified by metal affinity chromatography followed by size exclusion chromatography or by affinity chromatography using Protein L. Purified scFvs were able to inhibit gp complement system in a hemolytic assay and to detect gpC5 deposition in tissue. A surface plasmon resonance based assay on BIAcore was established, with which the C5 concentration in gp serum was determined to 240 microg/ml. As at least 0.04% of the normal gpC5 concentration can be detected, the test provides a powerful tool to investigate the development and the consequence of a hybrid complement system after liver xenotransplantation from gp to rat.

Acute Disease↗
PubMed1998

Behaviorally conditioned immunosuppression using cyclosporine A: central nervous system reduces IL-2 production via splenic innervation.

Bi-directional interactions between the central nervous system (CNS) and immune system are demonstrated by the modification of immune function using behavioral conditioning. However, the mechanisms by which the CNS achieves conditioned immunomodulation are still in question. Here, we report that the immunosuppressive effects of cyclosporine A (CsA) can be behaviorally conditioned in rats using saccharin as a gustatory conditioned stimulus. The conditioned effects were compared to control groups that received CsA paired with water (sham-conditioned), CsA injection on test days (CsA-treated), and unhandled rats (untreated). In conditioned animals, the mitogen-induced lymphocyte proliferation in the spleen is significantly suppressed, and the survival time of heterotopic heart allografts prolonged. These effects are paralleled by conditioned inhibition of IL-2 and IFN-gamma synthesis by splenocytes. Furthermore, the CNS-induced immunosuppression is mediated neuronally and not via the blood, since the conditioned reduction of proliferation and cytokine production is completely abrogated after surgical denervation of the spleen. Thus, during conditioning, the CNS learns to reinstate at demand a CsA-like immunosuppression via splenic innervation. This might be used as a supportive therapy for controlling immune functions.

Animals↗
PubMed1998

Behaviorally conditioned effects of Cyclosporine A on the immune system of rats: specific alterations of blood leukocyte numbers and decrease of granulocyte function.

Immunosuppression induced by Cyclosporine A (CsA) can be behaviorally conditioned. It is unknown, however, whether a taste aversion paradigm using CsA as an unconditioned stimulus (UCS) induces alterations of blood leukocyte numbers and function. Results obtained by three-colour flow cytometry and granulocyte chemiluminescence response demonstrate that in conditioned rats, absolute numbers of lymphocyte subsets, including B, CD8+ T cells and CD4+ naive and memory T cells, and granulocyte numbers and function were significantly decreased. In contrast to the conditioned response, CsA treatment alone increased lymphocyte numbers and did not affect granulocyte function. Thus, our data demonstrate that behaviorally conditioned CsA effects can be monitored in the blood. In addition, results indicate that the CNS mediates the behaviorally conditioned immunosuppression by reducing the availability and function of granulocytes and lymphocytes.

Animals↗
PubMed1998

[Early morphological changes in Crohn disease as further evidence for conservative resection indications].

Clinical studies revealed that the size of the margin of resection and the microscopic findings at the edge of the specimen did not influence the rate of recurrence. Regarding early lesions of Crohn's disease, the aim of the present study was to identify morphological alterations which are able to explain the clinical findings and are in accordance with the operative procedure. In the present study the resection margins of 29 patients with Crohn's disease were investigated using the scanning electron microscope. Seventy-three percent of patients with histopathologically unaffected resection margins in the small bowel and 71% in the large bowel showed early lesions. These consisted of mucosal architectural alterations, epithelial bridge formation and goblet cell hyperplasia and hypertrophy. Curative resection is not possible, independent of the resection margins. The morphological findings underline the correctness of the usual operative procedure, namely limited resections in Crohn's disease.

Crohn Disease↗
PubMed1998

Conditioned taste aversion produced by cyclosporine A: concomitant reduction in lymphoid organ weight and splenocyte proliferation.

The classical conditioning of immune parameters is commonly conducted within a conditioned taste aversion (CTA) paradigm. In this study, the immunosuppressive drug cyclosporine A (CsA) was investigated for its ability to produce both taste aversion to a novel stimulus and conditioned alterations in immune functioning. The paradigm comprised the pairing of a 0.2% saccharin solution (the conditioned stimulus; CS) with an intraperitoneal injection of 20 mg/kg CsA (the unconditioned stimulus; UCS). Upon saccharin re-presentation, a marked reduction in fluid consumption was observed, indicating aversion to the novel substance (=CTA). By using a single CsA/saccharin pairing the CTA lasted for one CS representation. However, by implementing three pairings, this effect could be extended for up to seven representations. No noticeable difference was recorded by adjusting the saccharin representation from every consecutive day to every second day. The most effective paradigm in creating CTA was subsequently investigated for its effectiveness in producing conditioned immune alterations. Animals were killed on the day of the third CS re-presentation, and immune functions assessed. Conditioned animals displayed a significant reduction in thymus and spleen weights. Effects on the spleen were further investigated, revealing a significantly reduced proliferative ability of isolated splenocytes to concanavalin A. These results demonstrate that the physiological effects produced by CsA are sufficiently salient to elicit CTA. Furthermore, the reduction in lymphoid organ weight and splenocyte proliferation induced by CsA are also conditionable using this paradigm.

Animals↗
PubMed1998

Cyclosporine A affects open field behavior in DA rats.

Since the introduction of Cyclosporine A (CsA) for immunosuppression in solid-organ transplantation, the rate of allograft rejection has decreased substantially. However, treatment with CsA induces neuropsychological complications in patients, including affective disorders such as anxiety, disorientation, depression, aggression, paranoia, and apathy. These CsA-induced affective side effects cannot be extensively studied in humans. Therefore, this study investigates the effects of intraperitoneal CsA (20 mg/kg) injections on the open-field behavior of male Dark Agouti (DA) rats 1, 6, 12, and 23 h after drug administration on 3 consecutive days. CsA induced an increase in emotionality in DA rats 6 h after injection, reflected by decreased ambulatory activity in the open field and increased defecation. In addition, a decrease in rearing activity was observed 12 h after CsA administration. These behavioral alterations are discussed in the view of changes in cytokine profiles induced by CsA.

Animals↗
PubMed1997

Coagulation activation in patients undergoing directional coronary atherectomy.

Restenosis is a major problem of percutaneous transluminal coronary angioplasty (PTCA) and related procedures. To better understand the underlying pathophysiologic mechanisms, coagulation and fibrinolytic variables were analysed prospectively in 35 patients after directional coronary atherectomy (DCA) and in 20 control patients undergoing diagnostic heart catheterisation and coronary angiography. Blood samples were taken before and 1 h, 24 h and 48 h after the procedure. No subacute thrombosis or unstable angina were documented in any patient. In 8 out of these 35 patients late restenosis was diagnosed during follow-up angiography 3-6 months after DCA. In these 8 patients prothrombin fragments (F1 + 2) rose from 0.7 to 0.9 nmol/l (P < 0.01) and thrombin-antithrombin III complexes (TAT) from 2.9 to 6.0 micrograms/l (P < 0.01), but not significantly in 27 patients without restenosis and in the control patients. In patients with late restenosis plasminogen activator inhibitor (PAI-1) also increased from 2.4 to 4.9 U/ml (P < 0.05) 24 h after DCA while there were no significant changes in patients without restenosis and in control patients. D-Dimer/TAT ratio reflecting the balance between clotting activation and fibrinolysis was significantly lower after 24 h in restenosis patients. The findings suggest that coagulation activation and hypofibrinolysis during 48 h after DCA might be associated with the development of late restenosis.

Adult↗
PubMed1997

[Determinants of the quality of life in chronic renal failure].

Dialysis patients, waiting for kidney transplantation, were asked about their quality of life. Data from 1027 persons have been collected. Compared to a population sample by the "Nottingham Health Profile" (NHP), dialysis patients showed double the frequency of symptoms--only for the subscale "pain" no significant difference could be recognised. Duration of dialysis treatment reduces the quality of life considerably: increasing troubles have been observed through different quality of life scales. Age shows less important influence concerning "pain" and "physical mobility", even a decrease of symptoms in elder patients has been demonstrated by NHP-subscales for "emotional reaction" and "social isolation". Gender, education, kind of disease and dialysis treatment, and the fact of former transplantations had only marginal influence on some different dimensions of life quality. The study demonstrates in which way the patients perception of life quality could be operational and integrated in analysis and evaluation of therapeutic procedures.

Activities of Daily Living↗
PubMed1997

[Function of the residual myocardium after infarct and prognostic significance].

Changes of the left ventricle after myocardial infarction are characterized by geometric, structural, and vascular alterations, which have been summarized under the term "remodeling". This process takes place in the infarct region as well as in the surviving myocardium. Depending on to the size of infarction and the degree of neurohumoral activation, the left ventricle demonstrates diastolic dysfunction which may finally lead to systolic failure. The residual myocardium develops progressive myocyte hypertrophy and interstitial fibrosis. These structural alterations are due to changes in loading conditions and stimulation of the neurohumoral system with an activation of local paracrine and autocrine factors. Myocardial function can be assessed by different non-invasive (echocardiography, radionuclide ventriculography, magnetic resonance imaging, etc.) or invasive methods (e.g., simultaneous pressure-volume measurements). "Myocardial tagging" based on magnetic resonance imaging allows the assessment of 3D-motion of the left ventricle by labelling specific myocardial regions with a rectangular grid. A systolic "wringing" motion with clock-wise rotation at the base and counter-clockwise rotation at the apex has been described in normal subjects. In the ischemic myocardium, delayed relaxation with a prolonged back-rotation (untwisting) has been reported during early diastole, whereas decreased systolic contraction with delayed diastolic rotation has been observed in non-Q-wave infarction. In patients with anterolateral aneurysms, a complete loss of systolic rotation has been demonstrated. The prognostic significance of LV "remodeling" has been emphasized by several authors: The size of infarction, LV volume, LV ejection fraction, as well as the degree of neurohumoral activation have been identified as being associated with an unfavorable clinical outcome. Yearly mortality rates have been reported to range between 15 and 17% in patients with large infarcts and marked LV dilatation and between 3 and 7% in patients with small to medium-sized infarcts.

Diagnostic Imaging↗
PubMed1997

[Aspects relevant for abdominal surgery of attempted suicide].

In this retrospective study of 24 patients who were treated at our clinic during the last 22 years after having attempted suicide, we evaluated aspects concerning abdominal- and transplantation surgery. There was a predominance of "hard" (70%) versus "soft" (30%) methods for suicide attempt. Intra-abdominal injuries resulting from attempted suicide by stabbing or shooting should lead to laparotomy-the prognosis is then good. Surgical treatment after intoxication, especially caustic ingestion, depends on endoscopic and clinical findings. The highly increased rates of suicide in patients with end-stage renal disease can be reduced significantly by kidney transplantation. The risk of suicide after transplantation is further diminished with improved immunosuppressive treatment. Only in a few cases there is an indication for liver transplantation-in some cases of fulminant hepatic failure caused by self-administered paracetamol overdose. Auxiliary liver transplantation may then be considered.

Abdominal Injuries↗