Venous thrombosis: clinical and experimental MR imaging

Five venous thrombi were induced in the external jugular veins of three laboratory dogs, and were repeatedly imaged over 3 weeks using a 0.35-T magnetic resonance (MR) imager. MR magnitude and phase images, T1 and T2 relaxation times, venography, and histologic sections of these thrombi were evaluated to determine the changes in appearance on MR images with time. Venous thrombi appeared hyperintense compared with muscle on both relatively T1- and T2-weighted spin-echo sequences regardless of the age of the clot. Organization of the thrombus beyond 1 week was manifested as increased prominence of flow signal void in and around the clot. Distinction between intraluminal thrombus and flow-related artifacts was aided by phase image reconstruction. Nineteen venous thrombi locations in 13 patients revealed an MR appearance similar to that of the experimental animal model. Three patients (six thrombi locations) had serial examinations over 4 weeks. No significant change in thrombus signal characteristics was noted with time. It is concluded that MR imaging at 0.35 T cannot be used to predict the age of thrombus (up to 3 weeks) but may be helpful in following its resolution.     

Rotator cuff tears: preliminary application of high-resolution MR imaging with counter rotating current loop-gap resonators

A new class of radio frequency (RF) coils for magnetic resonance (MR) imaging and spectroscopy is introduced. The coils consist of two loop-gap resonators of equal diameters positioned along a common axis. They are tuned to the mode in which the current in the two loops flows in opposite directions. These coils are "decoupled" from a uniform excitation field of arbitrary orientation (including circularly polarized fields) by intrinsic decoupling and by means of back-to-back fast recovery diodes. Measurements made with the coils and a phantom saline tank indicate that the signal-to-noise ratio obtainable with these coils is almost identical to that obtained with single loops. Imaging of several anatomic areas, including knee, wrist, and shoulder, has been performed with a 1.5-T MR system that uses circularly polarized RF. A small series of patients with torn rotator cuffs underwent imaging. Difficulties in establishing the diagnosis with MR imaging because of anatomic complexity are illustrated. The value of pulse sequences with long repetition times to increase the signal intensity of fluid in the joint is shown.     

The decline in US teen pregnancy rates, 1990-1995

OBJECTIVES: Estimate pregnancy, abortion, and birth rates for 1990 to 1995 for all teens, sexually experienced teens, and sexually active teens. DESISN: Retrospective analysis of national data on pregnancies, abortions, and births. Participants. US women aged 15 to 19 years. OUTCOME MEASURES: Annual pregnancy, abortion, and birth rates for 1990 to 1995 for women aged 15 to 19 years, with and without adjustments for sexual experience (ever had intercourse), and sexual activity (had intercourse within last 3 months). RESULTS: Approximately 40% of women aged 15 to 19 years were sexually active in 1995. Teen pregnancy rates were constant from 1990 to 1991. From 1991 to 1995, the annual pregnancy rate for women aged 15 to 19 years decreased by 13% to 83.6 per 1000. The percentage of teen pregnancies that ended in induced abortions decreased yearly; thus, the abortion rate decreased more than the birth rate (21% vs 9%). From 1988 to 1995, the proportion of sexually experienced teens decreased nonsignificantly. CONCLUSIONS: After a 9% rise from 1985 to 1990, teen pregnancy rates reached a turning point in 1991 and are now declining. Physicians should counsel their adolescent patients about responsible sexual behavior, including abstinence and proper use of regular and emergency contraception.     

The Second Stage of Labour: Durational Dilemmas

The optimal management of prolonged second stage of labour remains a confused area of thought and action. This confusion is particularly evident when epidural analgesia is also being used. A review of the literature indicates that prolonged duration of the second stage, i.e. from full dilation of the cervix until delivery, with or without epidural analgesia, has little adverse effect on perinatal outcome. More attention should be paid to the expulsive phase of the second stage and greater efforts made to reduce unnecessary interventions.     

Pulmonary angiography with iopamidol: patient comfort, image quality, and hemodynamics

The choice of a contrast agent for pulmonary angiography has important implications for patient comfort, image quality, and perhaps the safety of the procedure, particularly for "high-risk" patients. In a prospective study the nonionic, low-osmolality agent iopamidol eliminated the problem of image degradation due to coughing, and patients showed excellent tolerance for it. However, pressure measurements obtained within 3-5 minutes of injection of iopamidol and diatrizoate sodium meglumine 76% showed no significant difference in the hemodynamic effects of the two contrast agents, either for normotensive or for pulmonary hypertensive patients. Contrary to a common presumption, pulmonary hypertension by itself did not appear to increase the risk of pulmonary angiography. The theoretic presumption of greater hemodynamic stability with low-osmolality contrast agents was not clinically evident in this trial with iopamidol. At present, enhanced patient comfort and improved image quality remain the only confirmed bases for choosing this contrast agent for pulmonary angiography.     

Attitudes of general practitioners and midwives towards ethnicity-based haemoglobinopathy-carrier screening

Haemoglobinopathies (HbP) are severe autosomal recessive disorders with high prevalence among certain ethnic groups. World Health Organisation (WHO) advises implementing screening programmes for risk groups. Research in the Netherlands has shown that general practitioners and midwives do not perceive ethnicity as a risk factor for HbP. Moreover, registration of ethnicity is a controversial societal issue, which may complicate the introduction of a national preconception or antenatal carrier screening programme. This study investigates attitudes, intention and behaviour of general practitioners and midwives towards ethnicity-based HbP-carrier screening in general. A structured questionnaire based on the Theory of Planned Behaviour was sent by mail to a random selection of 2100 general practitioners and 1800 primary care midwives. Response was 35% (midwives 44.2% GPs 27.6%). Although 45% of respondents thought that offering a carrier test on the basis of ethnicity alone should become national policy, it is currently not carried out. The main factor explaining lack of intention towards ethnicity-based HbP-carrier screening was subjective norm, the perception that their peers do not think they should offer screening (52.2% variance explained). If ethnicity-based HbP-carrier screening would become national policy, most professionals report that they would carry this out. Most respondents favoured ethnicity registration for health purposes. As most practitioners look for role models among peers, debate among general practitioners and midwives should be encouraged when new policy is to be developed, articulating the voices of colleagues who already actively offer HbP-carrier screening. Moreover, primary care professionals and professional organisations need support of policy at national level.     

骨髓间充质干细胞治疗股骨头坏死的进展

目的:股骨头坏死是一种对髋关节具有特殊破坏性的退行性病变。近10年来,随着对成人股骨头坏死研究的不断深入以及骨髓干细胞技术的应用,成人股骨头坏死的治疗效果有了明显提高。文章综述骨髓间充质干细胞治疗股骨头坏死的研究进展。资料来源:应用计算机检索Pubmed1985-12/2006-12期间的相关文章,以“stem cell,mesenchymal cell,osteonecrosis of femoral head,femoral head necrosis,therapy”为检索词分别进行组合检索,文章语言种类限定为English。同时计算机检索中文CNKI全文数据库1980-12/2006-12期间的相关文章,以“干细胞,股骨头坏死,治疗”为检索词分别进行组合检索,并限定文章语言种类为中文。资料选择:对资料进行初审,并查看每篇文献后的引文。纳入标准:①干细胞的生物学特性。②股骨头坏死的发病原因和机制。③干细胞治疗股骨头坏死的实验或临床研究文献。排除标准:重复研究、Meta分析或综述类文献。资料提炼:共收集76篇相关文献,31篇符合纳入标准,排除的45篇文献为内容陈旧或重复。符合纳入标准的31篇文献中,分别涉及股骨头坏死的发病原因与发病机制、骨髓间充质干细胞的特性、骨髓间充质干细胞与生长因子、转基因骨髓间充质干细胞、骨髓间充质干细胞治疗股骨头坏死的适应证、骨髓间充质干细胞治疗股骨头坏死的移植方法等内容。资料综合:股骨头坏死是由多种病因造成的股骨头缺血和骨细胞坏死的病理过程,围绕其发病机制目前主要存在脂肪栓塞学说、骨细胞脂肪变性坏死学说等,都支持在股骨头发生缺血坏死后,骨髓内间充质干细胞的数量和活性均受到抑制的观点。因此,也可以将股骨头坏死认为是一种骨细胞和(或)间充质干细胞的疾病。骨髓间充质细胞来源于中胚层,具有多向分化潜能,而转基因干细胞不仅具有多向分化能力,同时还能表达特定转染基因,分泌目标活性因子,极大提高了干细胞修复骨坏死的效能。骨髓干细胞治疗股骨头坏死的方法包括局部注射移植、超选择性股骨头供血动脉移植、支架复合材料的移植以及相互间的联合应用等。结论:骨髓间充质干细胞治疗股骨头坏死早期患者,可以使其病情缓解甚至出现逆转,具有较好的应用前景,但在临床应用中仍有许多问题亟待解决。