钙拮抗剂TMB-8抑制BHQ,NE和KCl引起的培养乳牛基底动脉单个平滑肌细胞内游离钙的升高

用AR CM MIC阳离子测定系统,测量单个细胞内游离钙浓度([Ca²⁺]i),研究8-(N,N-二乙胺)-n-辛基 3,4,5-三甲氧基苯甲酸酯(TMB-8)对培养乳牛基底动脉平滑肌[Ca²⁺]i的作用。在细胞外钙浓度为1.3mmol·L^-1时,TMB-8(30μmol·L^-1)可明显抑制BHQ,NE及KCl引起[Ca²⁺]i的升高。在细胞外钙为零+EGTA 0.1mmol·L^-1时,TMB-8(10,30及100μmol·L^-1)可浓度依赖性地降低静息[Ca²⁺]i,TMB-8(30μmol·L^-1)可几乎完全阻断BHQ及NE引起[Ca²⁺]i的增加。研究表明TMB-8降低培养乳牛基底动脉平滑肌[Ca²⁺]i的机制,主要是抑制肌浆网Ca²⁺的释放,或增加肌浆网对Ca²⁺的摄入,并由此间接地抑制细胞外钙的内流。     

Image processing in digital radiography

Image processing is a critical part of obtaining high-quality digital radiographs. Fortunately, the user of these systems does not need to understand image processing in detail, because the manufacturers provide good starting values. Because radiologists may have different preferences in image appearance, it is helpful to know that many aspects of image appearance can be changed by image processing, and a new preferred setting can be loaded into the computer and saved so that it can become the new standard processing method.Image processing allows one to change the overall optical density of an image and to change its contrast. Spatial frequency processing allows an image to be sharpened, improving its appearance. It also allows noise to be blurred so that it is less visible. Care is necessary to avoid the introduction of artifacts or the hiding of mediastinal tubes.     

Storage phosphor digital mammography

Digital mammography using storage phosphor CR is still in the investigational stage. It is the only digital mammography system that has been tested in preliminary clinical trials with promising early results. Further clinical studies are needed to assess the impact of the limited spatial resolution of storage phosphor technology on its application as a digital screening mammography system. Further studies also are needed to determine the optimum image processing parameters needed in digital mammography.     

Acute cardiac and pulmonary arrest after infusion of vancomycin with subsequent desensitization

J Allergy Clin Immunol 1997;100:853-4.     

RELAXATION OF MESENTERIC ARTERY OF STROKE PRONE SPONTANEOUSLY HYPERTENSIVE RATS BY CALCIUM REMOVAL

1. The time courses of the relaxation, induced by removal of extracellular Ca2+, of K-depolarized mesenteric artery preparations from stroke prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY) were compared. 2. The time course of the decline in extracellular Ca2+ was estimated from the time course of the relaxation and the concentration-response curve of K(+)-depolarized preparations to Ca2+. The time course of the decline in the intracellular free Ca2+ concentration was also estimated from the reported relation between Ca2+ concentration and the contraction of skinned vascular smooth muscle. 3. The time course of relaxation was exponential, the curve being made up of three components. The time course was slower in preparations from SHRSP, especially the first component of the relaxation curve. 4. The time courses of the decline in the intracellular and extracellular Ca2+ concentrations were also exponential, being made up of three components and were also slower in the preparation made from SHRSP. 5. The wall and muscle layer of the mesenteric arteries used in the present experiments were significantly thicker in the SHRSP preparations. 6. Calculation of the half relaxation time, based on the diffusion of Ca2+ across the blood vessel wall, suggested that the slower relaxation in preparations from SHRSP is due largely to the thicker muscle layer, although differences in Ca2+ sequestration by the smooth muscle cells may also be involved.     

A combined course of primary health care practice and family medicine at the University of Gezira

The community-based course presented is a longitudinal course running through four semesters in the Faculty of Medicine, University of Gezira, Sudan. Students combine their regular work in primary health care centres with attachments to a number of families in Wad Medani town. They continue to visit these families regularly throughout their entire medical course with the aim of studying them and helping them with some of their medical and psychosocial problems.     

Mature-age entrants to medical school: a controlled study of sociodemographic characteristics, career choice and job satisfaction

A comparison of 121 mature-age and 270 normal-age entrants who graduated from the University of Queensland Medical School between 1972 and 1987 shows that mature-age entrants are some 7 years older, are more likely to come from public (state) schools and less likely to have parents in professional/technical occupations. Otherwise, the two groups were similar in terms of gender, marital status, number of children, ethnic background and current practice location. The educational background of mature-age entrants prior to admission includes 44.6% with degrees in health-science areas and 31.4% with degrees in non-health areas. Reasons for delayed entry of mature-age entrants include late consideration of medicine as a career (34.7%), financial problems (31.4%), dissatisfaction with previous career (30.6%), poor academic results (19.8%), or a combination of the above factors. Motivations to study medicine include family influences (more so in normal-age entrants), altruistic reasons (more so in mature-age entrants) and a variety of personal/social factors such as intellectual satisfaction, prestige and financial security (similar for both groups) and parental expectations (more so in normal-age entrants). Mature-age entrants experienced greater stress throughout the medical course, especially with regard to financial difficulties, loneliness/isolation from the students and family problems (a greater proportion were married with children). While whole-course grades were similar in both groups, normal-age entrants tended to win more undergraduate honours/prizes and postgraduate diplomas/degrees, including specialist qualifications. Practice settings were similar in terms of group private practice, hospital/clinic practice or medical administration, but there was a greater proportion of mature-age entrants in solo private practice, and a smaller proportion in teaching/research. If given the time over, some two-thirds of both groups would choose medicine as a career. Reasons for job satisfaction include helping patients, intellectual stimulation and financial rewards. Reasons for dissatisfaction include pressure of work, red-tape/paperwork, 'doctor-bashing', long working hours, emotional strain, financial pressure, unfulfilled career expectations and irritation with trivial medical complaints.