如何摄制高质量的精品课课堂教学录像片

精品课课堂教学录像片的摄制愈来愈受到重视。在介绍其一般形式和特点的基础上,指出直拍制作是精品课程录像片制作的最佳方式,并对直拍制作的特点以及拍摄过程和编辑进行了详细的分析,以期提高精品课课堂教学录像片的质量。     

Effects of prostacyclin inhibition on splanchnic hyposensitivity to glypressin in a hemorrhage-transfused rat model of portal hypertension

BACKGROUND: Hyposensitivity to vasopressin is a well-documented phenomenon in animals with portal hypertension and patients with cirrhosis and hemorrhage. Similar findings exist with infusion of glypressin (a long-acting vasopressin analogue), and this phenomenon could be ameliorated by inhibition of nitric oxide (NO) synthase. Besides NO, excessive formation of prostacyclin (PGI2) has been shown to play an important role in the development of hyperdynamic circulation and the mediation of hyporeactivity to vasoconstrictors in portal-hypertensive states. This study was designed to investigate whether the blockade of PGI2 activity by indomethacin infusion could enhance the portal-hypotensive effect of glypressin in portal-hypertensive rats with bleeding. METHODS: Portal hypertension was induced by partial portal vein ligation (PVL). Fourteen days after operation systemic and portal hemodynamics were measured in stable or bleeding PVL rats receiving intravenous glypressin (0.07 mg/kg) or indomethacin (5 mg/kg) followed by glypressin infusion. In rats with a hypotensive hemorrhage 4.5 ml of blood was withdrawn, and 50% of the withdrawn blood was reinfused before the administration of glypressin or indomethacin. RESULTS: Splanchnic hyposensitivity to glypressin was shown in hemorrhage-transfused PVL rats. Indomethacin infusion did not cause significant systemic and portal-hemodynamic changes in bleeding PVL rats (P > 0.05). The addition of indomethacin significantly enhanced the portal-hypotensive effects of glypressin and potentiated the increases in mean arterial pressure induced by glypressin infusion in bleeding PVL rats. CONCLUSIONS: The improvement of splanchnic hyposensitivity to glypressin in a hemorrhage-transfused rat model of portal hypertension by the administration of indomethacin suggests that PGI2 has in the development of this hyposensitivity.     

Nurses' perceived barriers to the implementation of a Fall Prevention Clinical Practice Guideline in Singapore hospitals

Background  

Theories of behavior change indicate that an analysis of barriers to change is helpful when trying to influence professional practice. The aim of this study was to assess the perceived barriers to practice change by eliciting nurses' opinions with regard to barriers to, and facilitators of, implementation of a Fall Prevention clinical practice guideline in five acute care hospitals in Singapore.     

Clinical and radiological features of generalised lymphangiomatosis

We report a paediatric patient who presented with fever, shortness of breath, and vague abdominal discomfort. Lesions removed surgically proved to be generalised lymphangiomatosis and were treated conservatively. The spectrum of abnormalities and radiological features are discussed.     

All-trans retinoic acid decreases susceptibility of a gastric cancer cell line to lymphokine-activated killer cytotoxicity.

All-trans retinoic acid (RA) was previously shown to regulate the growth of gastric cancer cells derived from the cell line SC-M1. This study was designed to investigate the effect of RA on the sensitivity of SC-M1 cells to lymphokine-activated killer (LAK) activity. RA at the concentration range of 0.001-10 microM was shown to induce SC-M1 cells to exhibit resistance to LAK activity in a dose-dependent manner. A kinetics study indicated that a significantly increased resistance was detected after 2 days of co-culturing SC-M1 cells with RA and reached a maximum after 6 days of culture. Similar results were obtained from two other cancer cell lines: promyelocytic leukaemia HL-60 and hepatic cancer Hep 3B. A binding assay demonstrated that the binding efficacy between target SC-M1 cells and effector LAK cells was not altered by RA. Flow cytometric analyses revealed that RA exhibited no effect on the expression of cell surface molecules, including HLA class I and class II antigens, intercellular adhesion molecule-1 and -2, and lymphocyte function antigen-3. Cell cycle analysis revealed that culture of SC-M1 cells with RA resulted in an increase in G0/G1 phase and a decrease in S phase, accompanied by a decrease in cyclin A and cyclin B1 mRNA as determined by Northern blot analysis. Additionally, RA was shown to enhance the expression of retinoic acid receptor alpha (RAR alpha) in SC-M1 cells, and to have no effect on the expression of RARbeta or RARgamma. Taken together, these results indicate that RA can significantly increase gastric cancer cells SC-M1 to resist LAK cytotoxicity by means of a cytostatic effect through a mechanism relating to cell cycle regulation. The prevailing ideas, such as a decrease in effector to target cell binding, a reduced MHC class I antigen expression or an altered RARbeta expression, are not involved.     

Post-transfusion HIV infection despite donor screening: a report of three cases

In August 1996, a blood donation was collected which subsequently infected three patients post-transfusion with HIV 1. The donation itself was originally screened as negative for anti-HIV 1/2 using a sensitive EIA method, but subsequently was shown to contain p24 Ag and HIV RNA by an amplification technique. The proposed introduction of nucleic acid testing of all blood donations in the UK for hepatitis C, hepatitis B and HIV may further reduce the remote risk of further episodes of post-transfusion infection. The infection in the index recipient was detected on routine pre-transplant virological screening but proved difficult to confirm, at a time when she had recently received myeloablative treatment for a haematological malignancy which impaired the immune response. There is a need for continued vigilance in such patients to exclude post-transfusion infection, at a time when natural immunological responses have been impaired by their disease or treatment.     

Pathologic features associated with nonsentinel lymph node metastases in patients with metastatic breast carcinoma in a sentinel lymph node

BACKGROUND: To the authors' knowledge it has not yet been determined which patients with primary breast carcinoma and an axillary sentinel lymph node (SN) metastasis have additional metastases in nonsentinel lymph nodes. METHODS: Pathologic features of the primary breast carcinoma and its SN metastasis were examined in 194 patients and correlated with the tumor status of the non-SNs in the same axillary basin. Two-level cytokeratin immunohistochemistry was applied to the SNs and to non-SNs of cases that were negative by standard hematoxylin and eosin examination. RESULTS: Lymph node staging based on SN findings, size of the primary tumor, and presence of peritumoral lymphatic vascular invasion (LVI) were associated with non-SN metastasis. The majority (63%) of the 101 patients with SN macrometastases had non-SN metastases. Extranodal hilar tissue invasion in conjunction with SN involvement also was strongly associated with non-SN metastasis (P = 0.0001) but was present in only 65% of patients (35 of 54 patients) with non-SN macrometastases. Approximately 26% of patients (24 of 93 patients) with SN micrometastases (相似文献   

乌拉地尔对冠脉旁路移植术中血压升高的阻抑作用

目的　探讨乌拉地尔对冠状动脉旁路移值术 (coronaryarterybypassgraft,CABG)开胸与关胸时血压升高的阻抑作用。方法　 6 8例CABG手术 ,麻醉方法一致 ,随机、双盲分为实验组 (n =4 8)和对照组 (n =2 0 )。实验组在锯 撑开胸骨前及关胸骨前即刻分别注射乌拉地尔 0 .3mg/kg和 0 .2mg/kg ,对照组则在相应时间注射生理盐水 1 0ml。结果　在锯 撑开胸骨及关胸骨两个时段 :实验组血压较平稳 ,对照组血压明显升高 (P <0 .0 5 ) ;实验组ST段无明显变化 ,对照组ST段有明显下移 (P <0 .0 5 )。实验组经历了体外转流的病例中 ,有 5例在关胸骨期间收缩压一过性低于 1 2kPa ,经快速输血好转。结论　乌拉地尔能明显阻抑CABG术开胸与关胸时的血压升高 ,并稳定心电图的缺血改变。