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31.
Tadashi Nakazawa Yoshiyuki Takami Robert Benkowski Satoshi Ohtsubo Ohashi Yukio Eiki Tayama Goro Ohtsuka Yoshinari Niimi Julie Glueck Akinori Sueoka Helmut Schmallegger Heinrich Schima Ernst Wolner Yukihiko Nosé 《Artificial organs》1997,21(7):597-601
Abstract: To be able to salvage heart failure patients, the need for an economical permanent ventricular assist device is increasing. To meet this increasing demand, a miniaturized centrifugal blood pump has been developed as a permanently implantable device. The Gyro permanently implantable model (PI-601) incorporates a sealless design with a blood stagnation free structure. The pump impeller is magnetically coupled to the driver magnet in a sealless manner. This pump is atraumatic and antithrombogenic and incorporates a double pivot bearing system. A miniaturized actuator was utilized in this system in collaboration with the University of Vienna. The priming volume of this pump is 20 ml. The overall size of the pump actuator package is 53 mm in height and 65 mm in diameter, 145 ml of displacement volume, and 305 g in weight. Testing to date has included in vitro hydraulic performance and hemolysis. This pump can provide 5 L/min against a 110 mm Hg total pressure head at 2,000 rpm and 8 Limin against 150 mm Hg at 2,500 rpm. The normalized index of hemo-lysis (NIH) value of this pump was 0.0028 g/100 L at 5 Limin against 100 mm Hg. A preliminary anatomical study revealed the possibility of the implantability of 2 such systems in biventricular bypass at a preperitoneal location. This system is feasible for use as a permanently implantable biventricular assist device. 相似文献
32.
Roelf Valkema MD Berthe L. F. van Eck-Smit MD Ernst E. van der Wall MD 《Journal of nuclear cardiology》1994,1(6):546-560
Noninvasive techniques for the assessment of cardiac metabolism are important for the detection of potentially salvageable
tissue in jeopardized areas of the myocardium. The correct identification of hibernating and stunned myocardium in patients
with severely depressed cardiac function can have vital therapeutic consequences for the patient. Changes in myocardial fatty
acid and glucose metabolism during acute and prolonged ischemia can be traced by positron-emitting or gamma-emitting radiopharmaceuticals.
Alternatively,31P-labeled magnetic resonance spectroscopy can be used for the assessment of high-energy phosphate metabolism. It is not yet
clear which modality will emerge as the most useful in the clinical setting. Positron emission tomography (PET) that uses
combinations of flow tracers and metabolic tracers offers unique opportunities for quantification and high-resolution static
and rapid dynamic studies. Currently, assessment of glucose metabolism with18F-fluorodeoxyglucose is regarded as the gold standard for myocardial viability and prediction of improvement of impaired contractile
function after revascularization. However, preserved oxidative metabolism may be required for potential functional improvement,
and therefore assessment of residual oxidative metabolism by11C-labeled acetate PET may prove to be more accurate than18F-fluorodeoxyglucose PET, which reflects both anaerobic and oxidative metabolism. Moreover, because fatty acids are metabolized
only aerobically, they are excellent candidates for the clinical assessment of myocardial viability and prediction of functional
improvement after revascularization. Especially derivatives of fatty acids that are not metabolized but accumulate in the
myocyte are attractive for myocardial imaging. Examples are123I-beta-methyl-p-iodophenyl pentadecanoic acid and 15-(o-123I-phenyl)-pentadecanoic acid. These tracers can be detected by planar scintigraphy and single-photon emission computed tomography,
which are more economical and widely available than PET. In addition, 511 keV collimators have been developed recently, making
the detection of positron emitters by planar scintigraphy and single-photon emission computed tomography feasible. The experience
with31P-labeled magnetic resonance spectroscopy in humans is still limited. With current magnetic resonance spectroscopic techniques,
insufficient spatial resolution is achieved for clinical purposes, but the possibility of serial measurements to monitor rapid
changes of phosphate-containing molecules in time makes magnetic resonance spectroscopy very valuable for the research of
myocardial metabolism. 相似文献
33.
Ross BD; Jacobson S; Villamil F; Korula J; Kreis R; Ernst T; Shonk T; Moats RA 《Radiology》1994,193(2):457
34.
35.
36.
Beat Morell Manuel Meyer Othmar Porr Ulrich Bay Ernst R. Froesch 《Acta diabetologica》1984,21(4):303-313
Summary The objective of this study was to follow the development of microalbuminuria and nerve conduction velocity under continuous
i.v. insulin therapy over a limited period of 4 months. For this purpose, 8 labile type I diabetics were selected (age 33±8
years, duration of diabetes 16±9 years) and treated conventionally with two insulin injections daily over 4 months. Afterwards,
the same patients were treated with continuous i.v. insulin infusion and finally again with two injections daily over 4 months
each. This procedure allowed each diabetic to serve as his own control. HbA1, microalbuminuria, nerve conduction velocity and relative refractory period of the ulnar nerve were checked at montly intervals.
During the continuous i.v. infusion over 4 months, blood sugar values were significantly lower, glucosuria had disappeared
almost completely and the glycosylated hemoglobin had fallen to near normal values. The mean rate of albumin excretion was
16±5 μg/min at rest and 76±26 μg/min during exercise (normal: 3.9±0.4 and 4.8±1.2 μg/min, respectively) and did not change
significantly. Nerve conduction velocity in the ulnar nerve rose significantly under i.v. insulin therapy from 47.9±0.6 m/sec
to 52±0.6 m/sec. Similarly, the relative refractory period of the same nerve fell significantly from 3.7±0.2 to 1.9±0.1 msec
(i.e. to within normal range). It is concluded that functional disturbances of peripheral nerve can regress by improved blood
sugar control with continuous i.v. insulin infusion over 4 months. On the other hand, incipient microangiopathy measured as
microalbuminuria remains unchanged over the same period of time. If an improvement is at all possible, considerably longer
periods of euglycemia are likely to be necessary.
Supported by Grant No. 3.964-0.80 from the Swiss National Science Foundation. 相似文献
37.
Rapid chemical kinetic techniques for investigations of
neurotransmitter receptors expressed
in Xenopus oocytes 下载免费PDF全文
Li Niu RaymondW. Vazquez Georg Nagel Thomas Friedrich Ernst Bamberg RobertE. Oswald GeorgeP. Hess 《Proceedings of the National Academy of Sciences of the United States of America》1996,93(23):12964-12968
Xenopus laevis oocytes have been used extensively during the past decade to express and study neurotransmitter receptors of various origins and subunit composition and also to express and study receptors altered by site-specific mutations. Interpretations of the effects of structural differences on receptor mechanisms were, however, hampered by a lack of rapid chemical reaction techniques suitable for use with oocytes. Here we describe flow and photolysis techniques, with 2-ms and 100-μs time resolution, respectively, for studying neurotransmitter receptors in giant (≈20-μm diameter) patches of oocyte membranes, using muscle and neuronal acetylcholine receptors as examples. With these techniques, we find that the muscle receptor in BC3H1 cells and the same receptor expressed in oocytes have comparable kinetic properties. This finding is in contrast to previous studies and raises questions regarding the interpretations of the many studies of receptors expressed in oocytes in which an insufficient time resolution was available. The results obtained indicate that the rapid reaction techniques described here, in conjunction with the oocyte expression system, will be useful in answering many outstanding questions regarding the structure and function of diverse neurotransmitter receptors. 相似文献
38.
Gert Jan Laarman Menco G. Niemeyer Albert V. G. Bruschke Fred J. Verzijlbergen T. Liam Go Ernst E. van der Wall Carl A. P. L. Ascoop 《European journal of nuclear medicine and molecular imaging》1989,15(5):239-243
To establish test specific normal limits for quantitative analysis of uptake and washout of 201Tl after dipyridamole infusion combined with low level exercise, 20 healthy volunteers were studied with low likelihood of coronary artery disease (CAD) assessed by a stepwise probability analysis based on age, sex, symptoms, resting electrocardiogram, and exercise electrocardiography. Likelihood of CAD in these volunteers was calculated as 1%. After dipyridamole infusion combined with low level exercise, one volunteer complained of headache; no other side effects were observed. There were no chest pain complaints. Maximal hemodynamic changes were achieved during the 6th and 7th min of the test. No ST segment depression was recorded. Visual analysis of the 201Tl scintigrams was normal in all volunteers. Mean regional washout at 4 h was 44.37%±2.11%. The regional washout in the 70° LAO view (46.65%±1.10%) was significantly higher than in the anterior and 30° LAO views (43.44%±1.50% and 43.02%±1.45%, respectively). Profiles of uptake and washout of 201Tl were different after dipyridamole infusion combined with low level exercise as compared to maximal exercise. Thus, in quantitative analysis of 201Tl scintigraphy after dipyridamole infusion in conjunction with low level exercise as applied in the present study, it is mandatory to use normal limits of uptake and washout of 201Tl derived from healthy volunteers who underwent the same combined protocol. 相似文献
39.
Spahn Hildegard Wellstein Anton Pflugmann Gabriele Mutschler Ernst Palm Dieter 《Pharmaceutical research》1989,6(2):152-155
Plasma concentrations of metoprolol after acute and repetitive administration of R/S-metoprolol to healthy volunteers were measured by a -adrenoceptor subtype-specific radioreceptor assay (RRA) and by an enantiospecific high-performance liquid chromatographic (HPLC) method. In the RRA, R/S-metoprolol showed a 20-fold 1-subtype selectivity: the S-( – )-enantiomer was 35-fold more potent than the R-( + )-enantiomer. A comparison between S-( – )-metoprolol concentrations detected in the plasma samples by HPLC and those detected by RRA yielded a 1/1 relationship, indicating that active metabolites are not present to a significant extent. These results were independent of the widely scattering metabolic clearance of metoprolol (with the potential of differences in the rate and extent of formation of active metabolites) in the volunteers. In general, HPLC methods can be validated by comparison with RRA in order to clarify whether active metabolites are present and—on the basis of the Ki value from RRA—whether the detection limit of the physicochemical procedure is sufficient to cover the therapeutically relevant range. 相似文献
40.
IFN-gamma-enhanced allergen penetration across respiratory epithelium augments allergic inflammation 总被引:2,自引:0,他引:2
Reisinger J Triendl A Küchler E Bohle B Krauth MT Rauter I Valent P Koenig F Valenta R Niederberger V 《The Journal of allergy and clinical immunology》2005,115(5):973-981
BACKGROUND: Respiratory allergen contact is the critical event in the elicitation and boosting of allergen-specific immune responses, as well as in the induction of immediate and late inflammatory reactions. OBJECTIVE: We sought to investigate the influence of various factors of allergic inflammation on the integrity and barrier function of respiratory epithelium for allergens. METHODS: We cultured the human bronchial epithelial cell line 16HBE14o- in a transwell culture system as a surrogate of intact respiratory epithelium and used purified iodine 125-labeled recombinant major birch pollen allergen (rBet v 1) to study the extent, kinetics, and factors influencing transepithelial allergen penetration. RESULTS: Culture supernatants from activated allergen-specific T H 1 clones decreased transepithelial resistance. A screening of various factors (histamine, IFN-gamma, IL-1beta, IL-2, IL-3, IL-4, IL-5, IL-8, IL-12, and TNF-alpha) identified IFN-gamma as a potent factor capable of reducing epithelial barrier properties and enhancing transepithelial allergen penetration. Increased submucosal allergen concentrations caused by IFN-gamma-mediated reduction of epithelial barrier function provoked a more than 7-fold augmentation of histamine release from sensitized basophils. CONCLUSION: These results demonstrate that the T H 1 cell-derived cytokine IFN-gamma facilitates allergen penetration through the respiratory epithelium and thereby can aggravate allergic inflammation. 相似文献