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排序方式: 共有214条查询结果,搜索用时 15 毫秒
1.
Linda H Distlehorst Elizabeth Dawson Randall S Robbs Howard S Barrows 《Academic medicine》2005,80(3):294-299
PURPOSE: To compare the characteristics and outcome data of students from a single institution with a two-track, problem based learning (PBL) and standard (STND) curriculum. METHOD: PBL and STND students from nine graduating classes at Southern Illinois University School of Medicine were compared using common medical school performance outcomes (USMLE Step 1, USMLE Step 2, clerkship mean ratings, number of clerkship honors and remediation designations, and the senior clinical competency exam), as well as common admission and demographic variables. RESULTS: PBL students were older, and the cohort had a higher proportion of women. The two tracks had similar USMLE Step 1 and 2 mean scores and pass rates. Performance differences were significant for PBL students in two clerkships as well as in the clerkship subcategories of clinical performance, knowledge and clinical reasoning, and noncognitive behaviors. In addition, the proportion of PBL students earning honors was greater. CONCLUSIONS: The traditional undergraduate educational outcomes for the PBL and STND students are very positive. In several of the clerkship performance measures, the PBL students performed significantly better, and in no circumstance did they perform worse than the STND students. 相似文献
2.
G E Hofmann C V Rao G H Barrows J S Sanfilippo 《The Journal of clinical endocrinology and metabolism》1983,57(2):360-366
The topography of prostaglandin (PG) E and F2 alpha receptors in uteri of premenopausal women was investigated by dividing uteri into six equal longitudinal strips and further dividing each strip into approximately 1-cm segments. Tissue for determination of smooth muscle content using the Trichrome stain was taken from each section, and the remainder was homogenized for binding studies with 3H-labeled PGs. The [3H] PGE1 binding (mean, 41.5 fmol/mg protein; range, 23.1-58.3) was about 8-fold greater in the fundus than [3H]PGF2 alpha binding (mean, 4.8 fmol/mg protein; range, 1.3-13.0), and this trend was found in most uterine sections. The binding of both 3H-labeled PGs decreased from fundus to cervix, and this decrease was similar to the decrease in smooth muscle content. Scatchard analysis revealed apparent dissociation constants (Kds) of 1.4 and 76 nM and apparent specific binding capacities (Ns) of 25 and 488 fmol/mg protein for [3H]PGE2, and Kd values of 11.5 and 81 nM and Ns values of 19.4 and 58 fmol/mg protein for [3H]PGF2 alpha in the uterine fundus. The Kd values for [3H]PGE2 were similar in other sections of the uterus, but the Ns values were smaller in the lower uterine body and cervical end. While the phase of the menstrual cycle did not influence [3H]PG binding, the diagnosis of abnormal uterine bleeding compared to dysmenorrhea was associated with an increase in [3H]PGE1 binding (P less than 0.05). 相似文献
3.
Crystal structure and characterization of a cytochrome c peroxidase-cytochrome c site-specific cross-link 下载免费PDF全文
Guo M Bhaskar B Li H Barrows TP Poulos TL 《Proceedings of the National Academy of Sciences of the United States of America》2004,101(16):5940-5945
A specific covalently cross-linked complex between redox partners yeast cytochrome c peroxidase (CCP) and cytochrome c (cyt. c) has been made by engineering cysteines into CCP and cyt. c that form an intermolecular disulfide bond in high yield. The crystal structure of the cross-linked complex has been solved to 1.88-A resolution and closely resembles the structure of the noncovalent complex [Pellitier, H. & Kraut, J. (1992) Science 258, 1748-1755]. The higher resolution of the covalent complex has enabled the location of ordered water molecules at the peroxidase-cytochrome c interface that serve to bridge between the two proteins by hydrogen bonding. As in the noncovalent complex, direct electrostatic interactions between protein groups appear not to be critical in complex formation. UV-visible spectroscopic and stopped-flow studies indicate that CCP in the covalent complex reacts normally with H(2)O(2) to give compound I. Stopped-flow kinetic studies also show that intramolecular electron transfer between the cross-linked ferrocytochrome c and the Trp-191 cation radical site in CCP compound I occurs fast and is nearly complete within the dead time ( approximately 2 ms) of the instrument. These results indicate that the structure of the covalent complex closely mimics the physiological electron transfer complex. In addition, single-turnover and steady-state experiments reveal that CCP compound I in the covalent complex oxidizes exogenously added ferrocytochrome c at a slow rate (t(1/2) approximately 2 min), indicating that CCP does not have a second independent site for physiologically relevant electron transfer. 相似文献
4.
A retrospective study of 38 women with preterm prematurely ruptured membranes was performed. Twenty were treated with intravenous hydrocortisone followed by timed delivery between 48 and 72 hours after initiation of steroid therapy. Eighteen were managed expectantly, with observation for labor and infection. There were no significant differences between steroid-treated patients and observed patients in the incidence of neonatal respiratory distress syndrome, perinatal mortality, or maternal or neonatal infections. 相似文献
5.
Interleukin-1 family expression in human breast cancer: interleukin-1 receptor antagonist 总被引:9,自引:0,他引:9
Miller LJ Kurtzman SH Anderson K Wang Y Stankus M Renna M Lindquist R Barrows G Kreutzer DL 《Cancer investigation》2000,18(4):293-302
We hypothesize that interleukin-1 alpha, beta, and receptor antagonist (IL-1 alpha, IL-1 beta, and IL-1 ra, respectively) are present and tumor cell associated in human breast cancer (HBC). We believe the levels of these cytokines in breast tumor homogenates relate to other known prognosticators of patient survival (i.e., estrogen receptor [ER] status). Our results demonstrated that, immunohistochemically, tumor cells express IL-1 alpha, IL-1 beta, and IL-1 ra in most specimens tested. In breast tissue homogenates, IL-1 alpha levels correlated inversely with ER levels (p < 0.06), whereas IL-1 ra levels correlated directly with both ER levels (p < 0.009) and IL-1 beta levels (p < 0.06). When analyzing cytokine levels for the ER (-) versus ER (+) patient groups, we found that in many instances these groups showed a different cytokine profile. These studies suggest that the IL-1 family of cytokines may be important in regulating protumorigenic activities within the HBC tumor microenvironment. 相似文献
6.
By the end of 1990-91, the Southern Illinois University School of Medicine had had six years of experience with comprehensive, performance-based examinations of senior medical students' levels of clinical competence; this report assesses the psychometric aspects of the six examinations given during that period. The examinations were aimed at determining the students' readiness for postgraduate training. Compared with other clinical performance-based assessments that use standardized patients (SPs), these examinations had two important and unique features: (1) the examinations assessed a comprehensive range of clinical skills and reasoning; and (2) they approximated the challenges of real clinical practice wherein a practitioner's skills need to be orchestrated and prioritized in order to meet the challenges of the case encountered. Each year, the performance-based assessment given was an intensive clinical examination requiring each student to work up 13 to 18 SP problems over a three-day period. To administer an examination to an entire class of students took three weeks. Because all students after the first year of administration (1986) were required to pass these examinations, the fairness of test design and scoring and the setting of performance standards for the examinations became important issues for the faculty. The results, accumulated over six years and based on a total of 6,804 student-patient encounters involving 405 students, indicate that this kind of clinical performance-based examination can discriminate a wide range of students' clinical performances. The results provide evidence for the examinations' test security, content validity, construct validity, and reliability. 相似文献
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9.
Liver tumors in women on contraceptive steroids. 总被引:2,自引:0,他引:2
The possible association between oral contraceptives and benign liver tumors has recently been reported. To date the majority of cases have been diagnosed as benign hepatomas (liver cell adenomas). We have had the opportunity to study 13 such cases. Eight have been examples of focal nodular hyperplasia of the liver; however, in addition, there were examples of hepatocellular carcinoma, liver cell adenoma, and possible liver cell hamartoma; all were in women on "the pill." Gynecologists are alerted to the fact that many of the patients present with symptoms of acute abdomen, syncope or shock, and intrahepatic or intraperitoneal bleeding. Prompt diagnosis and treatment may be lifesaving. 相似文献
10.
Pyridoacridines are marine natural products that contain planar structures. Almost all are cytotoxic and capable of DNA intercalation. Several pyridoacridines have demonstrated anti-cancer activity, being able to generate reactive oxygen species or to inhibit topoisomerase (Topo) II. Synthetic pyridoacridines were characterized and compared to other pyridoacridines as well as the Topo-inhibiting drugs (etoposide, 9-aminocamptothecin and wakayin) in a series of in vitro enzyme systems. We found AK37 was able to stabilize a DNA-Topo I cleavable complex, but not a DNA-Topo II cleavable complex. To our knowledge, this is the first report of a DNA-Topo I cleavable complex stabilizing pyridoacridine. Structure comparison studies demonstrated that this activity was lost when an extra 'F' ring was added, but activity was not affected when the 'D' ring was removed. AK37 inhibited the catalytic activity of both human Topo I and II. 相似文献