Environmental covariates: effects on the power of sib-pair linkage methods

The effect of inclusion of environmental risk factors on the power of sib-pair linkage methods was tested for a qualitative trait. It was found that inclusion of an environmental variable did not increase the power of the Haseman-Elston (H-E) sib-pair nonparametric linkage analysis test. However, a significant increase in power was observed for both the H-E and affected-sib-pair tests, even in small samples, when persons unexposed to the environmental risk factor were coded as unknown.     

Sham radiation in clinical trials assessing radiotherapy for exudative age-related macular degeneration

BACKGROUND: To evaluate the effectiveness of sham radiation treatments in masking patients to their randomization group in the Radiation of Age-Related Macular Degeneration (ROARMD) Study. METHODS: Patients with choroidal neovascularization complicating age-related macular degeneration were randomized to a treatment (RAD) group that received external beam irradiation (seven treatment sessions) or to a control (SHAM) group that received sham radiation (one sham treatment session). During a telephone survey, 62 of 73 randomized patients responded to the following questions: Do you think you received radiation? Why do you feel that way? Did the vision in your study eye worsen after enrollment? RESULTS: Eighty-one percent of the RAD group and 59% of the SHAM group thought that they had received radiation. In patients who thought that their vision had stabilized or improved, 82% thought that they had received radiation. In patients who thought that their vision was worse, only 39% thought that they had received radiation. In 54% of patients, subjective perception of vision influenced their guess as to whether they received radiation. CONCLUSIONS: Subjective patient perception of visual outcome was the most influential variable for masking. Variation between radiation treatment and sham session techniques, such as equipment used and duration of treatments, played a lesser role in the masking of patients. Seven treatment days correlated with a higher number of patients who thought that they had received radiation. Although our procedures do not strictly mask the two groups, one sham radiation session was effective in keeping patients guessing their randomization group.     

A Study of Lung Function and Chest Radiographs in Men Exposed to Zirconium Compounds

Men working with zirconium compounds at one site in the Northof England have been monitored since 1975 to evaluate effectson the lung of exposure (mainly<10mg/m³) over many years.Chest radiographs (in 1975, 1978, and 1982) and lung functionmeasurements (from 1975–1988) were carried out on allmen (178) known to have worked with the compounds and an estimateof cumulative exposure was computed from job title and likelyexposures in each era. No evidence was found that zirconiumexposure resulted in abnormal chest radiographs or impairedpulmonary function. Received       21 April 1995 Accepted       25 January 1996     

Thallium-201 myocardial perfusion scintigrams in the evaluation of aorto-coronary saphenous bypass surgery.

The effect of aorto-coronary bypass graft surgery (CBG) upon regional myocardial perfusion (RMP) was studied in 23 patients using thallium-201 myocardial perfusing imaging after exercise. We compared the changes in RMP with the clinical status and ECG's during graded treadmill exercise (GTX) before and after CBG. After CBG, the New York Heart Association's "functional class" improved from 3.2 +/- 0.1 (mean +/- SE) to 1.2 +/- 0.2, p less than 0.005. The GTX performance of the patients was also significantly improved postoperatively as judged by the total exercise time (11.7 +/- 0.6 min postop, compared with 7.2 +/- 0.5 min preop; p less than 0.005). Postoperative improved Tl-201 scintigrams were observed in 19 patients, but in only nine patients did the perfusion distribution return to normal. Thus, Tl-201 exercise scintigrams following CBG demonstrate improved RMP in most patients. Failure of regional myocardial perfusion to improve postoperatively, however, does not preclude marked alleviation of angina and improved exercise tolerance.     

Using the stages of change model to increase the adoption of physical activity among community participants

PURPOSE. This study examined the use of the stages of change model to design an exercise intervention for community volunteers. DESIGN. The "Imagine Action" campaign was a community-wide event incorporating the involvement of local worksites and community agencies. Community members registering for the campaign were enrolled in a six-week intervention program designed to encourage participation in physical activity. SUBJECTS. Six hundred and ten adults aged 18 to 82 years old enrolled in the program. Seventy-seven percent of the participants were female and the average age was 41.8 years (SD = 13.8). SETTING. The campaign was conducted in a city with a population of approximately 72,000 and was promoted throughout community worksites, area schools, organizations, and local media channels. MEASURES. One question designed to assess current stage of exercise adoption was included on the campaign registration form as were questions about subject name, address, telephone number, birthdate, and gender. INTERVENTION. The intervention included written materials designed to encourage participants to initiate or increase physical activity, a resource manual describing activity options in the community, and weekly "fun walks" and "activity nights." RESULTS. A Stuart-Maxwell test for correlated proportions revealed that subjects were significantly more active after the six-week intervention. Sixty-two percent of participants in Contemplation became more active while 61% in Preparation became more active. CONCLUSIONS. Most participants increased their stage of exercise adoption during the six-week intervention. This study provides preliminary support for use of the stages of change model in designing exercise interventions.     

Effect of autologous blood donation in patients undergoing elective spine surgery.

Autologous blood predeposit before elective surgery is a rapidly expanding transfusion practice. A 3-year analysis of an autologous blood predeposit program was conducted to assess its impact on orthopaedic spine surgery. It was concluded that, first, autologous blood donation has resulted in a reduction of homologous blood transfusions in patients undergoing elective spine procedures from 26% to 13% (P = .02). Second, autologous blood preoperative donation in elective spine surgery has increased significantly, so that autologous blood as an alternative to homologous blood transfusion now represents a standard of practice for elective spine surgery at the institution included in the study. Third, limitations of preoperative autologous blood procurement suggest that application of additional blood conservation interventions as alternatives to homologous blood would be important contributors to achieving "bloodless" surgery in this setting.     

Functional anatomy of the gastroesophageal junction

The study of the functional anatomy of the gastroesophageal junction allows for the demonstration of a double mechanism that combats the conflict of pressures that tends to lead to gastroesophageal reflux. On one hand, the LES, an intrinsic structure, is directly related to the muscle fibers of the organ and responds to a neurohormonal physiologic command. On the other hand is an anatomic entity, centered by the crura of the diaphragm, closely related to the movements of respiration. These structures constitute a second, extrinsic sphincter that gives rise to the zone of high pressure in the terminal esophagus. This role is difficult to assess, and its importance is underestimated. The proper functioning of these two mechanisms implies that the gastroesophageal junction remains in place within the diaphragmatic channel of the esophagus. Also important are the postural phenomena associated with the sloping position of the fundus. In patients with gastroesophageal reflux, the decrease of the pressure measured in the terminal esophagus accounts for the occurrence of reflux. Investigators concede that, under the influence of abdominal straining, the gastroesophageal junction tends to ascend into the diaphragmatic channel. The results are twofold: (1) the muscle fibers of the lower esophagus relax, explaining the incompetence of the intrinsic sphincter, and (2) the sphincteric zone is withdrawn from its muscular diaphragmatic environment. Physicians should consider these structures as a whole in approaching the surgical treatment of reflux. The construction of a periesophageal valve has no anatomophysiologic basis. A gastropexy procedure must be added to replace the gastroesophageal junction in its anatomic setting and keep it there. This procedure also allows retightening of the muscle fibers of the esophageal wall, which is essential in long-term surgical correction.     

PRIMARY INTRACRANIAL GERM CELL TUMORS: Clinicopathologic Review of 32 Cases

Primary intracranial germ cell neoplasms are rare tumors and constitute a heterogeneous group. We have reviewed 32 cases, over a 21-year period, from the University of Florida. The cases include 22 germinomas, 6 mixed germ cell tumors, and 4 teratomas. The clinical presentations in these cases were more closely related to the location of the tumor, that is, pineal or suprasellar, rather than the histologic subtype. Neuroimaging evaluation was useful in distinguishing between germinomas, teratomas, and other mixed germ cell tumors (MGCTs), primarily by evaluation of cystic versus solid lesions (teratoma versus germinoma), contents of cysts (teratoma versus MGCT), and infiltrative nature of the tumors (MGCT), although cytologic-histopathologic confirmation remains necessary. Germinomas responded favorably to radiation therapy with survival periods of over 16 years; MGCTs were treated with combination chemotherapy and radiation, with a markedly poorer prognosis. This study underlines the critical significance of histopathologic evaluation of the tumor in determining therapeutic interventions as well as prognosis.