Improved estimates of discordance ratios in twin studies

In the study of monozygotic twins relative to disease and risk factors, particular interest focuses on the subset who are discordant for some suspected risk factor (for example, smoking), since such twins constitute a natural case-control pair. In such studies, questionnaires designed to identify the status of all twin pairs are sometimes error prone and can yield misleading estimates of the concordance-discordance ratios. Greater efforts to verify the characteristics of apparently discordant pairs than to verify those of apparently concordant pairs can result in the 'unequal ascertainment' fallacy. Using the results of a questionnaire with known error rates and the 'apparent' frequencies yielded, we present unbiased, maximum likelihood estimates of the 'true' proportions of concordant and discordant pairs. concordant and discordant pairs. We also present approximate covariances among these estimates.     

荧光染料在视神经脊髓鞘形成期从轴突至少突胶质细胞的扩散

将真蓝(true blue)混悬液注入出生后7、14、28d大鼠眼球内,经过一定时间后,视神经内的轴突和少突胶质细胞被荧光标记。荧光强度在视神经眼球端强于视神经交叉端;出生后14～28d的幼鼠荧光标记明显强于出生后7d的幼鼠;不同年龄组的动物荧光标记普遍在注射荧光染料后的第5d显著增强。本研究表明,荧光染料可被视网膜的节细胞吸收,经轴突输送,然后,横向扩散到少突胶质细胞,扩散的通路可能是朗氏结旁区的轴胶连接。     

The relationship between maternal needs and priorities in a neonatal intensive care environment

AIM: The aim of this study was to investigate the nature and organization of maternal needs and priorities in a neonatal unit. BACKGROUND: The relationship between maternal needs and priorities appears to be an under studied area in neonatal nursing. METHODS: A quantitative survey was carried out based on 209 mothers with premature infants. Two self-assessment schedules were used: critical care maternal needs inventory (J. Leske, Heart and Lung 15, 27-42) and a ranking scale. The data were analysed with multivariate analysis. FINDINGS: Data analysis revealed clear priorities in maternal needs. In particular the need for accurate infant related information was a priority for 93% of the mothers. Good communication practices with professionals were also valued. The mothers displayed altruistic behaviour, and self-related needs took second place. It is proposed that maternal needs demonstrate a hierarchical organization. CONCLUSION: It is important for nurses to consider the individual needs of the mothers, simply because the satisfaction of these needs is essential for maternal well-being.     

Steroid trials in the assessment of reversibility of air flow limitation: a survey of current clinical practice of chest physicians

To evaluate how steroid trials are currently used in the assessment of reversibility of air flow limitation, a postal questionnaire was sent to 355 consultant members of the British Thoracic Society working in England and Wales; 253 questionnaires were returned (71% response rate). Two respondents did not undertake steroid trials; of the remaining 251, 75% prescribed 30-40 mg oral prednisolone, with the commonest treatment period being 2 weeks. A high dose steroid inhaler was sometimes used as an alternative by 31% of respondents. Although 71% of respondents made lung function measurements on several occasions before starting steroids and 76% made measurements during treatment, 78% assessed patients on only one occasion at the end of the trials to ascertain its outcome. Weight, blood pressure and glycosuria were measured less frequently after the steroid treatment compared to the pre-trial period. Blood glucose and serum electrolytes were infrequently measured both before and after treatment. Wide variations exist in steroid trial regimens and current practice may neither provide definitive evidence of treatment benefit nor an adequate safeguard for patients against potential side-effects.     

Five year study of prenatal testing for Huntington''s disease: demand, attitudes, and psychological assessment.

Adult predictive and prenatal testing programmes for Huntington's disease (HD) in Canada have been available since 1986. However, the demand for prenatal testing and the reasons why some people choose not to have the prenatal test for this late onset disorder have not been well documented. In addition, the knowledge and attitudes of adult predictive testing candidates and their partners about prenatal testing are not well known nor are the psychological effects of prenatal testing well understood. As of September 1991, 425 subjects had entered the Canadian Collaborative Study of Predictive Testing and, of these, 47 subjects or their partners had become pregnant. Of this group, 14 (30%) couples requested prenatal testing, 24 (51%) couples did not want prenatal testing, and nine (19%) at risk subjects had already received a decreased risk through adult predictive testing and, therefore, were not eligible for the prenatal test. Of the 14 couples who initially requested prenatal testing, seven withdrew. Thus, demand for the prenatal test by eligible candidates was 7/38 or 18%, which is much lower than the 32 to 65% expected based on early survey data. The most frequently cited reason for declining prenatal testing was the hope that a cure would be found in time for their children. While the majority of adult predictive testing candidates (71%) in our study had accurate information about definitive prenatal testing, many (63%) did not have a correct understanding of exclusion prenatal testing. Although no serious adverse events such as suicide planning or admission to psychiatric hospital have occurred, a particular need for careful counselling was identified for those at risk candidates and their partners who have one prenatal test and feel compelled to use the test again in future pregnancies. Even though prenatal testing for HD is not requested as often originally expected, it still remains a desired option for some at risk persons and their partners.     

Surface modification of poly(ether urethane urea) with modified dehydroepiandrosterone for improved in vivo biostability

In this study, a fatty acid urethane derivative of dehydroepiandrosterone (DHEA) was synthesized and evaluated as a polyurethane additive to increase long-term biostability. The modification was hypothesized to reduce the water solubility of the DHEA and physically anchor the additive in the polyurethane during implantation. Polyurethane film weight loss in water as a function of time was studied to determine the polymer retention of the modified DHEA. The polyurethane film with unmodified DHEA had significant weight loss in the first day (10%) that was previously correlated to rapid leaching of the additive. The polyurethane film with modified DHEA had significantly less weight loss at all time points indicating improved polymer retention. The effect of the modified DHEA additive on the biostability of a poly(ether urethane urea) was examined after 5 weeks of subcutaneous implantation in Sprague-Dawley rats. Optical micrographs and infrared analysis of the specimens indicated that the modified DHEA bloomed to the surface of the film forming a crystalline surface layer approximately 10-15 microns thick. After explantation, this surface layer was intact without measurable differences in surface chemistry as monitored by attenuated total reflectance-Fourier transform infrared spectroscopy. There was no evidence of degradation of the polyurethane underneath the modified DHEA surface layer as compared with the polyurethane control. We have concluded that the modified DHEA self-assembled into a protective surface coating that inhibited degradation of the polyurethane. The roughness of the modified DHEA surface layer prevented adherent cell analysis to determine if the additive retained the ability to down-regulate macrophage activity. Subsequent studies will investigate the ability of surface-modifying additives to modulate cellular respiratory bursts in addition to the formation of an impermeable barrier. This bimodal approach to improving biostability holds great promise in the field of polyurethane biomaterials.     

Typifications. The first step for clinical diagnosis in psychiatry

Reigning views on psychiatric nosology regard as "too subjective" certain features of diagnosis which respected psychiatrists have reported and several empirical studies have confirmed. We describe two of these persistent "mysteries" of psychiatric nosology: rapid diagnoses and the praecox feeling. We then demystify these mysteries by explicating the workings of "typification" in the diagnostic process. The criteria of disorders which are provided by classification manuals, such as DSM-III, are shown to presuppose such typifications. Psychiatric typification, although a preconceptual skill, can be rendered fully scientific and objective.     

Expressions of resistance and cross-resistance in teniposide-resistant L1210 cells

Summary Resistance to teniposide (VM-26) by VM-26 selected resistant L1210 cells in culture was attributed to alterations in the flux of VM-26 across the plasma membrane and to functions of homogeneously staining regions that appeared on one or more chromosomes. In the present study, electrophoresis of membrane-cytosol fractions of these resistant sublines demonstrated a protein band, M_r 22 kd, that was not evident in similar fractions of drugsensitive L1210 cells or three revertant sublines. The distribution of this protein among various cellular fractions could be altered by manipulation of the concentration of calcium ions. A representative subline, LIa5 M, was observed to have vesicles that reacted with Sudan black B stain, an indication of altered lipid metabolism. The LIa5 M subline was cross-resistant to etoposide, vincristine, doxorubicin, amsacrine, and actinomycin D. Concentrations of VM-26 that inhibited cell division to the same extent caused an accumulation of fewer cells in the G₂ stage of cell division in LIa5 M cultures than in L1210 cultures. These observations indicate that the LIa5 M subline expressed multiple drug resistance, as well as changes in the expression of cytotoxicity to VM-26.This investigation was supported by Research Project Grant CA 35319, by Cancer Center Support (CORE) Grant CA 21765 from the National Cancer Institute, and by the American Lebanese Syrian Associated Charities.Recipient of research support from a training grant, American Cancer Society Grant IN-85-06, to the University of Tennessee Center for the Health Sciences     

Lung cancer and occupation in New Mexico

The association between occupation and lung cancer risk was examined in a population-based, case-control study of 506 patients (333 males and 173 females) and 771 control (499 males and 272 females) subjects in New Mexico. A personal interview was used to obtain lifetime occupational and smoking histories and self-reported history of exposures to specific agents. High-risk jobs were identified in advance of data analysis and linked with industrial and occupational codes for hypothesis testing. For females, lung cancer risk was not associated with employment history, but power was limited. For males, elevated risks were found for the uranium mining industry [odds ratio (OR) = 1.9; 95% confidence internal (CI) = 0.8-4.9], underground miners (OR = 2.1; 95% CI = 1.1-3.7), painters (OR = 2.7; 95% CI = 0.8-8.9), and welders (OR = 3.2; 95% CI = 1.4-7.4). For self-reported exposure to any of 18 agents, only the OR for exposure to "other metals" was elevated. The population attributable risk in males was estimated as 14% for employment in any high-risk industry or occupation with an OR above 1 in this study.     

Teacher Evaluation of an Experiential Vegetable Education Program for Australian Primary Schools: Does Face-to-Face Training Add Value above Digital Training?

The teacher-led implementation of healthy eating programs in schools is cost-effective and potentially impactful. Teacher acceptability is important for uptake; however, process evaluations are scarce. This study evaluated the effect of two intensities of teacher training on the evaluation of a vegetable education program for Australian primary schools by teachers. The teachers (n = 65) who implemented the program as part of a cluster RCT (25 schools in two states, New South Wales and South Australia) received either low- (provision with materials and online training) or high (additional face-to-face (F2F) training)-intensity training prior to implementing a 5-week vegetable education program. They evaluated the acceptability of a digital training module and program by indicating the level of agreement with 15 and 18 statements, respectively, using 5-point Likert scales. The average item scores ranged from 3.0 to 4.2. All but one item, including student engagement, alignment to the curriculum and intent for reuse of the program, had a rounded average or median score of 4. The level of training intensity did not impact the teacher acceptability ratings. In conclusion, the teacher acceptability was good, and additional F2F training does not add value above the solely digital training of the teachers.