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1.
Armin W. Geiger M.D. F.I.C.A. Alexander M. Zarubin Ph.D. Marc Hertel Anke Fahrenkamp M.D. Gert von Bally Hans H. Scheld M.D. F.I.C.A. 《The International journal of angiology》1995,4(1):46-50
Dysfunction of heart valve prostheses—mechanical as well as biological—is a common problem in cardiac surgery. The reasons for the valve failures are still not well understood. Biological valves especially have an unsatisfactory durability; degeneration and calcification very often lead to the failure of the valves. In our opinion, hidden defects present in the valve material prior to implantation of the valves is a plausible explanation for the dysfunction. Hitherto there has been no technique to detect these defects without destructing the specimen. Holographic interferometry proved to be applicable forin vitro evaluation of mechanical heart valve prostheses. In the present paper we describe application of this method to biological valves. Nine porcine bioprostheses and four fresh porcine aortic valves were investigated by means of holographic interferometry. In eight of nine bioprostheses, the results showed irregularities of the leaflet structure which depend on anomalies of the connective tissue of the leaflets of the valves. To make sure that these findings are not due to normal variations of the morphology, the investigations were carried out with fresh and unfixated porcine aortic valves. In the latter, no such anomalies of the structure were detected. The results obtained confirm the above hypothesis on the origin of the later valve dysfunction. Thus, holographic interferometry tests of bioprostheses prior to their implantation prevent the use of potentially dysfunctional valves.Presented at the 35th World Congress, International College of Angiology, Copenhagen, Denmark, July 1993 相似文献
2.
H. von Zitzewitz C. Düber P. Gutjahr W. Kersjes M. Thelen 《World journal of urology》1995,13(4):226-229
Summary During the past few years, a new tumor type has emerged in the pediatric and adolescent group of cancer patients, which has been designated malignant peripheral neuroectodermal tumor (MPNT). This tumor has some clinical and pathological signs in common with either soft-tissue sarcomas or classic Ewing's sarcoma, but is defined as a distinct entity because of its immunohistological characteristics. The tumor expresses neuronal markers, but the pattern varies: chromogranin, neuron-specific enolase, synaptophysin, protein S-100 and others. MPNT can occur in the urogenital region. The differential diagnosis on clinical grounds must include Ewing's and soft tissue sarcomas, and also Wilms' tumor and its variants. MPNT are often wide spread in the urogenital region when first diagnosed. Response to radiotherapy and combination chemotherapy is limited. Radical surgery is not always possible. The prognosis therefore remains rather poor at this time. A selection of MPNT patients is presented to demonstrate the various problems associated with this diagnosis. MRI and CT of all patients showed large tumors with direct infiltration of the surrounding structures. MRI is the best imaging modality for diagnosis and therapy monitoring in these tumors, because of its high soft-tissue contrast. 相似文献
3.
Robert A Bucek Stefan Puchner Armin Kanitsar Thomas Rand Johannes Lammer 《Journal of endovascular therapy》2007,14(1):70-76
PURPOSE: To evaluate the feasibility and accuracy of automated analysis software for use with multidetector computed tomographic angiography (CTA) in the exact grading of internal carotid artery stenosis. METHODS: A retrospective pilot trial was performed using CTA datasets from 87 stenotic carotid arteries in 46 consecutive patients (34 men; median age 73.5 years) with known cerebrovascular disease. Internal carotid artery (ICA) stenosis was graded according to NASCET criteria by 2 experienced vascular radiologists in consensus using axial source images as well as curved planar reformations and digital subtraction angiography (DSA). These results were then compared to those obtained from the automated CTA analysis software and the results of manually adapted automated CTA analysis. RESULTS: Measurements from automated CTA analysis as well as manually adapted automated CTA analysis correlated significantly to those of axial/reformatted CTA and DSA (r=0.53 and r=0.82, r=0.58 and 0.70, respectively, all p<0.05). Compared to axial/reformatted CTA measurements, automated CTA analysis had a median difference of -16%, while manually adapted automated CTA had a difference of -10%. Corresponding differences in a comparison with DSA were +4% and -2%, respectively. Circumferential calcification or kinking of the ICA origin did not significantly interfere with these differences (all p>0.05). Sensitivities for the detection of ICA stenosis >70% by manually adapted automated CTA analysis and automated measurement were 44.2% and 34.9%, respectively, versus axial/reformatted CTA. Compared with DSA as the gold standard, the sensitivities were 54.2% and 62.5%, respectively. Specificities for both methods and gold standards all exceeded 90%. CONCLUSION: Commercially available automated CTA analysis is a feasible tool, but sensitivities are still not sufficient for clinical application. 相似文献
4.
Role of angiotensin II in dynamic renal blood flow autoregulation of the conscious dog 总被引:2,自引:1,他引:1
Armin Just Heimo Ehmke† Uwe Wittmann† Hartmut R. Kirchheim¶ 《The Journal of physiology》2002,538(1):167-177
The influence of angiotensin II (ANGII) on the dynamic characteristics of renal blood flow (RBF) was studied in conscious dogs by testing the response to a step increase in renal artery pressure (RAP) after a 60 s period of pressure reduction (to 50 mmHg) and by calculating the transfer function between physiological fluctuations in RAP and RBF. During the RAP reduction, renal vascular resistance (RVR) decreased and upon rapid restoration of RAP, RVR returned to baseline with a characteristic time course: within the first 10 s, RVR rose rapidly by 40 % of the initial change (first response, myogenic response). A second rise began after 20–30 s and reached baseline after an overshoot at 40 s (second response, tubuloglomerular feedback (TGF)). Between both responses, RVR rose very slowly (plateau). The transfer function had a low gain below 0.01 Hz (high autoregulatory efficiency) and two corner frequencies at 0.026 Hz (TGF) and at 0.12 Hz (myogenic response). Inhibition of angiotensin converting enzyme (ACE) lowered baseline RVR, but not the minimum RVR at the end of the RAP reduction (autoregulation-independent RVR). Both the first and second response were reduced, but the normalised level of the plateau (balance between myogenic response, TGF and possible slower mechanisms) and the transfer gain below 0.01 Hz were not affected. Infusion of ANGII after ramipril raised baseline RVR above the control condition. The first and second response and the transfer gain at both corner frequencies were slightly augmented, but the normalised level of the plateau was not affected. It is concluded that alterations of plasma ANGII within a physiological range do not modulate the relative contribution of the myogenic response to the overall short-term autoregulation of RBF. Consequently, it appears that ANGII augments not only TGF, but also the myogenic response. 相似文献
5.
Rats injected intravenously with oleic acid developed pulmonary edema leading to hypoxia and hypercarbia. These changes were accompanied by an increase in immunoreactive endothelin (ir-ET) in plasma as early as 15 min after injection. At 45 min after injection plasma levels peaked at 114 +/- 19 pg/ml plasma (n = 8) and reached basal levels again after 240 min. In contrast, much larger amounts of ir-ET were found in the bronchoalveolar lavage fluid, with a peak at 120 min (2878 +/- 258 pg/lung, n = 7) preceding the maximum hypoxia observed at 180 min. In both plasma and bronchoalveolar lavage fluid samples ir-ET was characterized by reverse-phase HPLC as a mixture consisting mainly of ET-1 and smaller amounts of big ET-1, ET-2 and ET-3. In light of the biological effects of ET, the data suggest that these peptides might be of pathophysiological significance in this model of adult respiratory distress syndrome. 相似文献
6.
Uwe Fuchs Armin Zittermann Ole Suhr Gösta Holmgren Gero Tenderich Kazutomo Minami Reiner Koerfer 《American journal of transplantation》2005,5(5):1159-1162
Senile systemic amyloidosis (SSA) results from deposition, predominantly in the heart, of amyloid fibrils derived from wild-type transthyretin (T TR) molecules. Cardiac autopsies indicate that SSA progressively increases in subjects 80 years of age and older. However, only a few cases of patients with SSA and cardiac failure have been recognized by cardiac biopsies during life. Here, we report a case of heart transplantation in a 68-year-old male patient with SSA. After cardiopulmonary resuscitation in October 1998, he underwent complete evaluation. Myocardial biopsies revealed the presence of amyloid deposition. Immunohistochemical staining of the amyloid indicated T TR. Genomic DNA analysis of the T TR exons did not result in any identification of a mutation. In 2001, heart transplantation was performed because progressive heart failure occurred. At the 1-year follow-up, no amyloid deposits were found in the donor heart. At the 2-year follow-up, the patient's physical and mental health was excellent. We conclude that heart transplantation can be an effective treatment in progressive heart failure due to SSA. 相似文献
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9.
Successful application of non operative procedures for gallstone therapy are limited on cholesterol stones. Therefore reliable therapeutic analysis of stone components is mandatory for planning of an adequate therapy. Computed tomographic gallstone analysis is considered to improve selection of patients significantly. However, standardized conditions for investigation of patients are not yet established. It is suggested that computerized tomography should be performed using 4 mm slides, standardized position of patients and a phantom, which allows calibration of different CT-machines. 相似文献
10.
The recruitment and co-contraction of lumbar muscles were investigated during the voluntary development of slowly and rapidly varying trunk flexion and extension, lateral bending, and axial twisting moments. Myoelectric signals were recorded from 14 lumbar muscles in nine young men during maximum voluntary exertions and cyclic isometric exertions. System identification techniques were used to calibrate dynamic models of the relationship between myoelectric signals and force. To assess co-contraction, the predicted muscle forces were subdivided into a task-moment set of muscle forces that minimally satisfied moment equilibrium and a co-contraction set of muscle forces that produced zero net moment. The sum of co-contraction muscle forces was used to quantify the degree of co-contraction present. Co-contraction was largely dependent on the direction of exertion and relatively less dependent on the subject or the rate of exertion. Co-contractions were estimated to contribute approximately 16–19% to the sum of muscle forces at a lumbar cross section during attempted extension of the trunk. Estimated co-contractions during attempted lateral bending and axial twisting were two to three times greater, which demonstrates that co-contraction is a major determinant of spinal loading in these tasks. This analysis suggests that substantial contractions of lumbar muscles, especially during asymmetric exertions, are used for reasons other than equilibrating moments at the L3-L4 level. 相似文献