Improving science literacy and education through space life sciences.

The National Space Biomedical Research Institute (NSBRI) encourages open involvement by scientists and the public at large in the Institute's activities. Through its Education and Public Outreach Program, the Institute is supporting national efforts to improve Kindergarten through grade twelve (K-12) and undergraduate education and to communicate knowledge generated by space life science research to lay audiences. Three academic institution Baylor College of Medicine, Morehouse School of Medicine and Texas A&M University are designing, producing, field-testing, and disseminating a comprehensive array of programs and products to achieve this goal. The objectives of the NSBRI Education and Public Outreach program are to: promote systemic change in elementary and secondary science education; attract undergraduate students--especially those from underrepresented groups--to careers in space life sciences, engineering and technology-based fields; increase scientific literacy; and to develop public and private sector partnerships that enhance and expand NSBRI efforts to reach students and families.

Elimination of stick-slip of elastomeric sutures by radiofrequency glow discharge deposited coatings.

Fine elastomeric sutures intended for cardiovascular surgery can exhibit "stick-slip" behavior as they are pulled through tissue; the resulting oscillatory force can damage delicate tissue or cause sutures to snap. To eliminate this undesirable effect, sutures were surface-modified using a radiofrequency glow discharge in a vapor of either hexamethyldisiloxane or hexamethyldisilazane, to produce a thin polymeric coating on the suture. The same coatings were also deposited onto aluminized tape to facilitate their characterization by measurement of air/water contact angles and by X-ray photoelectron spectroscopy. Coatings from both monomers were found to be very hydrophobic. The hexamethyldisiloxane glow discharge coatings underwent negligible oxidation when stored in air, and thus remained stable over a shelf-life period akin to what may be required of sutures. The hexamethyldisilazane glow discharge coatings, in contrast, incorporated substantial amounts of oxygen over a 3-month period. The coatings did not measurably alter the tensile properties of the sutures. The frictional properties of coated sutures were assessed by measuring the dynamic friction between the suture and ovine myocardium. Both coatings were effective in removing the inherent stick-slip behavior of polybutester sutures in this model. The coatings remained intact after several passes and proved to be robust and efficacious under various strain regimes.

Biofragmentable anastomosis ring for laparoscopic bowel surgery.

Laparoscopic surgery is now being applied for colonic resection, and one of the key challenges is fashioning a sound anastomosis. The biofragmentable anastomosis ring, a modern version of the Murphy Button, has been utilized in a series of experiments to develop and evaluate laparoscopic anatomotic techniques. A series of purpose-built devices were used to fashion left and right simulated colectomies as well as for a variety of other anastomoses. Survival animal experiments were performed and demonstrate the feasibility of this technique.

Comparison of titanium and absorbable polymeric surgical clips for use in laparoscopic cholecystectomy.

The use of hemostatic surgical clips is crucial in laparoscopic surgery. Metal clips can cause significant interference with computerized tomography, may have poor holding power, and may erode into important anatomic structures. Polymeric absorbable clips, which have advantages over metallic clips, are evaluated in this study. In vitro and in vivo studies were undertaken to evaluate the hold force, rate of degradation, tissue reactivity and safety of absorbable polymeric clips. Absorbable and titanium clips were applied across excised canine cystic ducts and both axial and transverse pull-off forces were measured. In the second phase, absorbable clips were implanted subcutaneously into male rats and the strength remaining within the clips was measured after 7, 10, 14, or 21 days. In phase 3, 30 pigs were randomized into six groups and each animal underwent a laparoscopic cholecystectomy. The cystic duct and artery were ligated with absorbable polymeric clips (experimental group) or titanium clips (control group). Animals were sacrificed at 7, 14, or 28 days and a celiotomy was performed. Intraabdominal adhesions were assessed and scored. The force required to dislodge the absorbable clip was significantly greater than for metallic clips for both axial and transverse forces. Absorbable clip strength retention decreased over time as expected with a retention of 11% original strength by the 21st day. Adhesions were highest when bile spillage occurred, but did not differ significantly between either clip type. Absorbable polymeric clips were hemostatically effective in this laparoscopic model and may offer advantages over metallic clips.

Clinical investigations: taking a global approach, part I.

Clinical investigations are a vital part of the development process of a medical device. A number of advantages can be gained by initiating a global approach to clinical investigation and implementing a well-designed, multinational, multicentred programme. It can mean that market approval can be accelerated and that the marketing effort is supported in specific countries, which can lead to greater market share. This article, which will be published in two parts, outlines the strategy that is required to set up and implement an effective global clinical investigation. Part I considers the elements that are involved and defines the advantages of adopting this approach.

Repair of incompetent venous valves: a new technique.

Current techniques for treating chronic venous disease caused by venous valve incompetence all have deficiencies. A need exists for a simple technique to restore competence to the diseased valves at multiple sites in the venous system. The Venocuff is an implantable device developed to restore venous valve competence by reducing the vein circumference. Two animal models are described that are useful in the study of venous valve incompetence; the device was tested in these two models in the jugular vein of sheep. The first model was of naturally incompetent valves. The device was implanted around 11 completely incompetent and seven partially incompetent valves in 18 veins of 11 sheep. After implantation competence was restored or improved in all valves. The second model made use of an arteriovenous fistula to produce incompetence in the jugular vein in four sheep. The implant increased the pressure difference across the valve from 16 to 68 mm Hg. The Venocuff implant was thus effective at restoring valvular competence in the two animal models studied. There is evidence that valvular incompetence in these models and the results observed may be applicable in some cases of chronic venous disease in humans.

Mortality of radiologists and pathologists in the Radiation Registry of Physicians.

The overall and cause-specific mortality experience of male radiologists and a comparable group of medical specialists, pathologists, who were included in the Radiation Registry of Physicians, is presented. The study population consists of an early-entry cohort of physicians who were members of either the American College of Radiology or the College of American Pathologists as of Jan. 1, 1962, and a late-entry cohort of similar members who joined these societies between January 1962, and June 1972. The purpose of the study was to determine if occupational exposure to low levels of ionizing radiation resulted in excess mortality from all causes and specific causes, or decreased survival patterns for radiologists compared with pathologists over the 16-year period, 1962 to 1977. The data revealed that radiologists and pathologists were comparable regarding overall mortality experience for all entrants, the early-entry cohort, and the late-entry cohort. Further analyses revealed a gradient in mortality between the two specialties, with the largest differences in the earliest birth subcohorts for all three groups, and a significant excess in mortality among radiologists in those subcohorts of the late-entry cohort born before 1920. Such a gradient may indicate an exposure effect associated with time of first exposure or duration of exposure, but not associated with time of entry into a professional society. Nevertheless, overall age-specific and age-adjusted mortality rates among radiologists and pathologists were lower in the late-entry cohort compared with the early-entry cohort, thus indicating some effect of time of entry within each specialty.(ABSTRACT TRUNCATED AT 250 WORDS)

Personal usage of medical radiological procedures by radiologists, pathologists, and their families.

The Radiation Registry of Physicians was established to study the biologic effects of prolonged occupational exposure to low levels of ionizing radiation. Questionnaire responses from radiologists and a comparable group of medical specialists, pathologists, provided information about personal and familial exposure to medical radiation. This first report from the 1973 survey of radiologists and pathologists (5077 and 2914 respondents, respectively) shows that a significantly greater percentage of male radiologists, their spouses and their children reported diagnostic and therapeutic radiographic procedures than did male pathologists and their immediate family members. Responses from female physicians show similar relationships but the number of such specialists is too small for meaningful analysis. The exposure differential between radiologists and pathologists suggests that personal medical radiation exposure is an important component of the total x-ray exposure of radiologists.