Updated deterministic radiation transport for future deep space missions.

NASA's deterministic transport code HZETRN, and its three-dimensional (3D) counterpart, 3DHZETRN, are being used to characterize the space radiation environment over a wide range of scenarios, including future planned missions to the moon or Mars. Combined with available spaceflight measurements, these tools provide the fundamental input for risk models used to quantify possible astronaut health decrements and satisfy agency limits in support of exploration initiatives. Further research is therefore needed to improve radiation transport and nuclear physics models while at the same time continuing to expand the available measurement database (ground-based and spaceflight) to validate such efforts. In this work, significant updates to the deterministic radiation transport models are presented. Charged muons and pions are fully coupled with the existing solutions developed for neutron and light ion (Z ≤ 2) transport. This update includes the 3D nature of pion production as well as the pion interactions, resulting in further production of energetic nucleons within shielding. Additional updates related to low energy proton recoils in hydrogenous materials and capture/decay processes associated with charged pions at rest are also described. Included in this work is the coupling of single and double-differential cross sections from Geant4 into HZETRN and 3DHZETRN. This enables a direct comparison of deterministic and Monte Carlo transport methodologies using the same nuclear databases for specific interactions. Comparisons between Geant4 and 3DHZETRN are shown and establish that the transport methodologies are in excellent agreement when the same cross sections are used. The deterministic codes are also compared to ISS data, and it is found that the updated 3D procedures are within measurement uncertainty (±5%) at cutoff rigidities below 1 GV, which approaches free space conditions.

Physiology and treatment of retained fetal membranes in cattle.

Retained fetal membranes (RFM) in cattle have adverse effects on fertility and production. Understanding the pathophysiology and causes of RFM is important for managing this disease. The hormonal processes that lead to normal placental separation are multifactorial and begin before parturition. A variety of risk factors, including early or induced parturition, dystocia, hormonal imbalances, and immunosuppression, can interrupt these normal processes and result in retention of the placenta. Current research does not support the efficacy of many commonly practiced treatments for RFM. Systemic administration of antibiotics can be beneficial for treating metritis after RFM, but antibiotic administration has not been shown to significantly improve future reproduction in cows with RFM. Collagenase injected into the umbilical arteries of retained placentas specifically targets the lack of placentome proteolysis and might enhance placental release. However, such therapy is costly and its benefits in terms of improving subsequent reproductive function have not been evaluated.

Examination of gills from salmonids with bacterial gill disease using monoclonal antibody probes for Flavobacterium branchiophilum and Cytophaga columnaris.

Bacterial diseases of the gills of commercially reared salmonids in freshwater are common problems. They accounted for 18% of all diagnostic submissions to the Atlantic Veterinary College from commercial fish hatcheries. Definitive diagnosis is difficult because of the growth characteristics of the putative bacteria in culture. Research into the pathogenesis of these diseases has also been similarly limited. Monoclonal antibodies (MAbs) were developed to 2 globally significant gill bacterial pathogens, Flavobacterium branchiophilum, the causative agent of bacterial gill disease, and Cytophaga columnaris, the causative agent of columnaris disease of salmonids. These MAbs were then used as the basis for an indirect fluorescent antibody test to assess archived cases of gill disease in our study region. Of the cases tentatively diagnosed based on histopathology as bacterial gill disease, 76.2% tested positively with the MAbs to F. branchiophilum. Also present within 18.7% of these cases were bacteria which reacted positively to the MAbs for C. columnaris. We conclude that the MAbs produced are valuable diagnostic and research probes for common bacterial disease of the gills of salmon and trout in Atlantic Canada. This study also adds further proof that F. branchiophilum acting alone can be sufficient cause for bacterial gill disease.

A preliminary evaluation of hydroxyurea for the treatment of rheumatoid arthritis.

OBJECTIVE: To obtain preliminary evidence on the safety and efficacy of low dose hydroxyurea as a treatment for rheumatoid arthritis (RA). METHODS: Five patients with active RA unresponsive to conventional therapy were entered into a 12 week, open label trial of hydroxyurea followed by a one month postdrug evaluation. RESULTS: Three of the 4 patients completing the study had a decrease in morning stiffness and number of swollen and tender joints. All 4 patients had a decrease in pain and an increase in function as measured by a modified health assessment questionnaire. No patient had improvement in sedimentation rate, C-reactive protein, or subjective measures of global well being. However, 3 of the 4 patients had disease flare after the drug was withdrawn, demonstrated by increased number of swollen and tender joints. CONCLUSION: Low dose hydroxyurea may be effective in the treatment of RA, but confirmation will require further testing by a randomized double blind placebo controlled trial of patients with a broader spectrum of disease severity over a longer period of therapeutic intervention.

Changes in quadriceps femoris muscle strength using isometric exercise versus electrical stimulation.

Reports in the literature appear to support the effectiveness of electrical stimulation as a means of increasing strength in normal muscles. The objective of this study was to measure and compare quadriceps muscle torque, isometrically and isokinetically, in three groups: 1) control group subjects (N = 9) did not alter their daily activities for 5 weeks, 2) isometric exercise group subjects (N = 10) exercised their quadriceps femoris muscle using maximum voluntary isometric exercises 3 times per week for 5 weeks, and 3) electrical stimulation group subjects (N = 10) who had 10 quadriceps femoris muscle contractions produced by electrical stimulation, 3 times per week for 5 weeks. No strength changes were noted in the control group; ANOVA revealed significant strength increases (P < 0.05) for both the electrical stimulation and isometric exercise groups. J Orthop Sports Phys Ther 1987;8(11):537-541.