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981.
BACKGROUND: Recently, the automated cardiac output method (ACM) was introduced for the calculation of blood flow at the left ventricular outflow tract (LVOT). This study was performed to examine the possibility of using ACM for flow calculation at the level of the mitral valve and for the quantification of mitral regurgitation (MR) in vitro and in vivo. METHODS AND RESULTS: In a computer-controlled in vitro model of the human heart, aortic and mitral normal bioprosthetic valves were inserted. ACM and electromagnetic probe flow measurements correlated well at the LVOT and at the mitral level (r2 = 0.79 and 0.77, respectively). For stroke volumes ranging from 30 to 100 ml/beat, there was no statistically significant bias between ACM and electromagnetic flow probe (-1.5 and 1.3 ml for LVOT and mitral level, respectively). Limits of agreement were [-14; +11] ml and [-18; +16] ml, respectively. We evaluated 68 patients in our in vivo study. They were divided into three groups according to the results of "standard" echocardiographic Doppler methods for the semiquantification of MR: echocardiographic color Doppler cartography, intensity of the continuous wave Doppler spectra, and in some patients, pulmonary venous flow, conventional Doppler, and proximal isovelocity surface area quantitative data. Group 1 consisted of 35 patients without MR or a physiologic one; the 17 patients in group 2 had a mild MR (1-2/4) and in group 3, 16 patients with MR 3-4/4 were included. Regurgitant volume (RV) was calculated as the difference between ACM mitral flow and ACM aortic flow, and regurgitant fraction (RF) was defined as the ratio between RV and ACM mitral flow. When mitral flow was measured only from the four-chamber view, we found in group 1, RV = -0.57 (0.67) L/min and RF = -16% (19%); in group 2, RV = -0.31 (1.06) L/min and RF = -8% (19%); and in group 3, RV = 1.53 (0.94) L/min and RF = 23% (13%). RV and RF were statistically higher in group 3 compared with group 2 or group 1 (p < 0.0005), but no significant difference was found between groups 1 and 2. When mitral flow was measured by the mean value of ACM four-chamber and two-chamber views, this resulted in group 1, RV = -0.26 (0.63) L/min and RF = -8% (15%); in group 2, RV = 0.01 (1.04) L/min and RF = -2% (18%); and in group 3, RV = 2.07 (1.21) L/min and RF = 34% (19%). RV and RF were again significantly higher in group 3 (p < 0.0001). There was no significant difference between group 1 and group 2, but in group 1 RF was no longer statistically different from 0%. CONCLUSIONS: (1) In our in vitro setting, ACM is reliable both at the LVOT and at the mitral valve. (2) In the in vivo situation, some overlapping does exist between the three groups of MR. However, ACM is a very easy, rapid, and objective method to differentiate hemodynamic nonsignificant (<3/4) from significant (> or =3/4) MR. Together with other well-known methods for the quantification of MR, it should facilitate the gradation of MR in the clinical setting. The absence of significant differences between group 1 and group 2 proves that the accuracy of ACM measurements at the mitral valve needs to be ameliorated before ACM can be used as a gold standard for the noninvasive measurement of RV and RF.  相似文献   
982.
Baker's cysts were treated operatively in 19 patients in the Department of Traumatology of the University of Cologne from 1988 to 1997. The subjective and objective results were evaluated with a questionnaire and a clinical examination and sonography (follow-up: 95%). All patients were examined before surgery, sonography and X-ray of the knee were performed. We differentiated between the congenital primary cyst (39%), and the secondary form, which was always associated with an intraarticular lesion (61%). Arthroscopy was performed in all secondary forms of Baker's cyst. Postoperative complications were two reinterventions due to one hematoma and one effusion. Patient's evaluation of operation result was "excellent" in 61% and "good" in 39% of cases. All knee joints had a full range of motion. There was only one case of a recurrent cyst. The primary form of Baker's cyst has always to be extirpated, according to our clinical experience. The extirpation of the secondary Baker's cyst and the relevance of arthroscopy and treatment of the basic disease have to be discussed.  相似文献   
983.
Although numerous studies have documented a role for B7-1 (CD80) in the induction of antitumor CTL immunity, it is presently unclear to what extent expression of this costimulatory molecule truly endows tumors with significant in vivo APC (antigen-presenting cell) capacity. Recent studies have, in fact, demonstrated that cross-priming, rather than direct priming, may constitute the major mechanism of CTL induction by B7-1 expressing tumors. We have, therefore, investigated the requirements for antigen density and costimulatory molecules in direct CTL priming with a prototype cell-based vaccine that uses a signal sequence-containing minigene to direct expression of a tumor-specific CTL epitope to the endoplasmic reticulum. This design limits sources of antigen available to professional APC in the host and, thereby, the contribution of cross-priming. Induction of antitumor CTL immunity by our prototype APC was shown to solely involve direct priming, independent of host APC, NKI.1+ cells, and CD4+ T cell help. CTL induction through this mechanism required the engineered APC to express the B7-1 molecule as well as a sufficiently high density of peptide/MHC complexes at its surface. Our data, in contrast to previous studies using modified tumor cells, clearly define the antigenic and costimulatory requirements for a suitably engineered "artificial" APC to directly prime peptide-specific CTL in vivo, and demonstrate that the signal sequence minigene approach allows the engineering of highly effective and well-defined cellular vaccines for activation of CTL against epitopes of choice.  相似文献   
984.
BACKGROUND: The College of American Pathologists has suggested that institutions should establish guidelines for the evaluation of the hernia sac. In addition, some states require the submission of this tissue for pathological evaluation. Yet, neither evidence-based guidelines nor published reviews for the evaluation of the pediatric hernia sac are available. Therefore, this retrospective study was conducted to document experience with the evaluation of the pediatric hernia sac. METHODS: All reports of the evaluation of hernia sacs submitted to the Department of Pathology during an 8-year period were reviewed. The case of any report that differed in any way from "consistent with hernia sac" was evaluated for the effect of the findings on the clinical course. RESULTS: A total of 7,924 hernia sacs were submitted on 6,034 patients. Microscopic evaluation was performed on 534. A total of 7,567 (95.4%) submitted specimens on 5,743 patients were "consistent with hernia sac" and demonstrated no other findings. Three hundred fifty-seven specimens contained findings in addition to hernia sac. In no patient did the results of the evaluation have an effect on the patient care. CONCLUSIONS: There is strong evidence that the routine pathological evaluation of pediatric hernia sacs offers little relevant clinical information. Mandatory tissue submission of hernia sacs should be reconsidered.  相似文献   
985.
Stimulus equivalence is a behavioral approach to analyzing the "meaning" of stimulus sets and has an implication for clinical psychology. The formation of three-member (A --> B --> C) stimulus equivalence classes was used to investigate the effects of three different sets of sample and comparison stimuli on emergent behavior. The three stimulus sets were composed of Rational-Emotive Behavior Therapy (REBT)-related words, non-REBT emotionally charged words, and a third category of neutral words composed of flower labels. Sixty-two women and men participated in a modified matching-to-sample experiment. Using a mixed cross-over design, and controlling for serial order effects, participants received conditional training and emergent relationship training in the three stimulus set conditions. Results revealed a significant interaction between the formation of stimulus equivalence classes and stimulus meaning, indicating consistently biased responding in favor of reaching criterion responding more slowly for REBT-related and non-REBT emotionally charged words. Results were examined in the context of an analysis of the importance of stimulus meaning on behavior and the relation of stimulus meaning to behavioral and cognitive theories, with special appraisal given to the influence of fear-related discriminative stimuli on behavior.  相似文献   
986.
By implementing a scanning near-field optical microscope into the specimen chamber of a scanning electron microscope, cathodoluminescence can be locally detected in the optical near-field. The achievable spatial resolution in this set-up is only limited by the size of the aperture in a coated fibre probe and its separation from the sample, rather than by the energy dissipation volume of the primary electrons and diffusion processes of excess carriers inside the specimen. We demonstrate how electronically active defects in polycrystalline diamond can be distinguished and localized with sub-wavelength lateral resolution by spectral filtering of the cathodoluminescence signal.  相似文献   
987.
Cramer RM  Chin R  Balk LJ 《Journal of microscopy》1999,194(PT 2-3):542-544
Ultra-large-scale integrated devices have been investigated by a reflection mode scanning near-field optical microscope designed for semiconductor analyses. Although it could be found that imaging the reflectivity of metal structures buried underneath thin, optically transparent passivation layers is practicable, shading of the reflected light by the SNOM probe complicated the interpretability of the achieved results. This issue has been overcome by using the SNOM probe as both illumination source and detector, simultaneously. The application of focused ion beam milling to the probes has allowed the increase of the transmittivity of the probes to such an extent that coated fibres could be utilized and the interpretability of the results could be enhanced. Furthermore, the investigated structures are of great interest for an investigation of z-motion artefacts, as the presence of the polished passivation layers allows topographical influences to be distinguished from pure optical contrast.  相似文献   
988.
Bulk single crystal of 4-aminobenzophenone with a size of 25 mm dia. and 35 mm length has been grown by vertical Bridgman technique. The crystal system of the grown crystal was confirmed by X-ray diffraction analysis. Crystalline perfection was analysed by high resolution X-ray diffraction studies. Chemical etching was carried out for the first time in 4-aminobenzophenone single crystal to study the defects presented in the grown crystal and the growth mechanism involved. Several organic etchants were employed with different etching time to select suitable etchant for studying dislocation pattern and other structural defects existing in the grown crystal. Etch patterns such as spirals and striations observed for the selective etchants provide considerable information on growth mechanism of the crystal.  相似文献   
989.
990.
Sum and sum-of-product algorithms, some designed to minimize significance error, are compared and recommendations for usage are offered. A simplified method of rounding is presented and the benefit of using it demonstrated. Results are presented for the IBM 360 as well as the IBM 7040 computers with obvious application to some other machines.  相似文献   
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