Spinal emergencies.

True spinal emergencies are rare and represent a potential loss of function if not treated properly. This review describes the most frequently encountered spinal emergencies. Early diagnosis is the key to preventing significant morbidity in the form of permanent disability. The recognition of red flags, followed by a thorough neurologic exam and appropriate imaging, should prompt a thorough examination with a heightened sense of urgency regarding the workup for serious forms of pathology. Spinal emergencies threaten loss of function if not treated properly. Providers must be aware of the presenting symptoms and be able to accurately interpret imaging results in order to promptly diagnose and treat these conditions.

Personal health management--a better way to wellness.

A risk management approach to disease prevention and health care utilization allows identification of the high-risk portion of an employee population. Benefits administrators can then implement strategies to manage costs for this small employee group.

A model of stress and burnout in collegiate coaches: effects of gender and time of season.

This investigation examined a model of stress and burnout in male (n = 131) and female (n = 118) collegiate head baseball and softball coaches. The model hypothesized that personal/situational variables of coaching issues, social support, hardiness, gender, and win/loss record predict stress appraisal which, in turn, predicts burnout. A preliminary gender by time of season repeated measures analysis indicated significant main effects for gender and time. Path analyses were conducted to test the model separately for males and females at the end of the season only. Results partially supported the model: Both male and female coaches higher in coaching issues and lower in hardiness were higher in perceived stress, and males lower in social support satisfaction were higher in perceived stress. Both male and female coaches' stress appraisal was predictive of all burnout components. The coaches were classified as suffering from moderate to high levels of emotional exhaustion and low to moderate levels of depersonalization and personal accomplishment.

An examination of personal/situational variables, stress appraisal, and burnout in collegiate teacher-coaches.

Following Smith's (1986) cognitive-affective model of stress and burnout in athletics, this investigation examined (a) the relationship of personal/situational variables (social support, gender, and years of experience) to stress appraisal and (b) the relationship of stress appraisal (perceived stress, coaching issues, and role conflict) to burnout. Male (n = 99) and female (n = 115) teacher-head basketball coaches from NCAA Division III and NAIA colleges completed established measures of burnout, perceived stress, teacher-coach role conflict, and social support and a measure of coaching issues developed for this study. Multivariate analyses supported the hypothesized relationships. Specifically, greater satisfaction with social support, less experience, and gender (females higher) were related to stress appraisal, and all stress appraisal variables were positively related to burnout. Contrary to previous studies, these teacher-coaches reported moderate to high levels of burnout.

Planning for aging in the twenty-first century.

The population of Rhode Island is aging more rapidly than that of most states and, therefore, can be used to illustrate the effects of aging on health systems, effects that may occur somewhat later or less extensively in most other states. Rhode Island population projections indicate a lull in aging between 1990 and 2010, followed by a 50 percent increase in the elderly cohort as the post-World War II "baby boom" population becomes 65 years of age and older between 2010 and 2030. Current (constant) Rhode Island rates of physician visits and hospital and nursing home use were applied to the projected population and translated into physician and hospital bed requirements and health expenditures, demonstrating that the resource costs of aging will be very large between 2010 and 2030 unless health service needs are reduced substantially and/or alternatives to hospital and nursing home services are developed. During the next 30 years, there will exist a unique and critical opportunity to restructure the medical care system. By developing alternatives to hospital inpatient care and nursing home care and by investing in primary, secondary, and tertiary prevention efforts, the baby boom population may remain healthier longer and, therefore, may require less medical care than elders today.

Fixation of dinitrogen derived from denitrification of nitrate in a photosynthetic bacterium, Rhodopseudomonas sphaeroides forma sp. denitrificans.

Studies with 15N demonstrated that the phototrophic bacterium Rhodopseudomonas sphaeroides forma sp. denitrificans strain IL106 cannot assimilate NO-3 but rather denitrifies it to N2. This strain also fixed N2 into cell protein, although nitrogenase activity was partially inhibited in the presence of NO-3. Strain IL106 did not assimilate NO-3, but growing cultures and washed cell suspensions incorporated the tracer from 15NO-3 via denitrification to 15N2 and then via nitrogenase into cell nitrogen. This incorporation was inhibited in cells supplied with NH4+ or in the absence of light, thus confirming the participation of nitrogenase in the assimilation of nitrogen from nitrate. This represents a novel type of N2 recycling in a photodiazotrophic denitrifying bacterium.

Inhibition of nitrogenase activity by metronidazole in rhodopseudomonas capsulata.

Inhibition of photosynthetic growth of Rhodopseudomonas capsulata by metronidazole was dependent on the nitrogen supply in culture solutions. Cultures fixing dinitrogen were more susceptible to inhibition by low concentrations than those supplied with NH4+. Light-dependent C2H2 reduction and H2 production by washed cells were inhibited by 80% and 60% respectively by 1 mM metronidazole. When this compound was first reduced with H2-palladised asbestos prior to assay, it only partially restricted C2H2 reduction in washed cells (33%) compared with unreduced inhibitor (68%). Metronidazole was without effect on other metabolic functions. Thus, even at 40 mM it did not inhibit either (a) dark or light respiration in cells grown under photo- and chemo-heterotrophic conditions; (b) H2-dependent photoreduction of 14CO2; (C) gamma-glutamyltransferase activity of glutamine synthetase in cell-free extracts (25 mM inhibitor). Metronidazole (1 mM) completely inhibited C2H2 reduction by washed cells of Azotobacter vinelandii. The dithionite-dependent C2H2 reduction of a partially purified nitrogenase was only partially inhibited (30%) by 1 mM metronidazole.

Hydrogenase activity in Rhodopseudomonas capsulata: relationship with nitrogenase activity.

Hydrogenase activity was found in cells of Rhodopseudomonas capsulata strain B10 cultured under a variety of growth conditions either anaerobically in the light or aerobically in the dark. The highest activities were found routinely in cells grown in the presence of H2. The hydrogenase of R. capsulata was localized in the particulate fraction of the cells. High hydrogenase activities were usually observed in cells possessing an active nitrogenase. The hydrogen produced by the nitrogenase stimulated the activity of hydrogenase in growing cells. However, the synthesis of hydrogenase was not closely linked to the synthesis of nitrogenase. Hydrogenase was present in dark-grown cultures, whereas nitrogenase synthesis was not significant in the absence of light. Unlike nitrogenase, hydrogenase was present in cultures grown on NH4+. Conditions were established which allowed the synthesis of either nitrogenase or hydrogenase by resting cells. We concluded that hydrogenase can be synthesized independently of nitrogenase.

Continuous monitoring, by mass spectrometry, of H2 production and recycling in Rhodopseudomonas capsulata.

Hydrogen evolution and consumption by cell and chromatophore suspensions of the photosynthetic bacterium Rhodopseudomonas capsulata was measured with a sensitive and specific mass spectrometric technique which directly monitors dissolved gases. H2 production by nitrogenase was inhibited by acetylene and restored by carbon monoxide. An H2 evolution activity coupled with HD formation and D2 uptake (H-D exchange) was unaffected by C2H2 and CO. Cultures lacking nitrogenase activity also exhibited H-D exchange activity, which was catalyzed by a membrane-bound hydrogenase present in the chromatophores of R. capsulata. A net hydrogen uptake, mediated by hydrogenase, was observed when electron acceptors such as CO2, O2, or ferricyanide were present in the medium.

Effect of light nitrogenase function and synthesis in Rhodopseudomonas capsulata.

The metabolic versatility of the purple nonsulfur photosynethetic bacterial permits the expression of either a phototrophic or a dark aerobic mode of growth. These organism also possess nitrogenase activity which may function under semiaerboic conditions. On the basis of these important properties, the light dependence of nitrogenase function and synthesis in Rhodopseudomonas capsulata was investigated. Nitrogenase activity was strictly dependent on light; no activity was observed in the dark, even when energy (ATP) was supplied by oxidative phosphorylation. It was concluded that the low-potential reducing agent required by the nitrogenase-catalyzed reaction could only be generated by a photochemical reaction. Nitrogenase biosynthesis was also largely dependent on light; however, a small amount of synthesis was observed in resting cells incubated in the dark. Resting cells prepared from dark-grown cultures synthesized nitrogenase at high rates upon illumination. The highest stability of nitrogenase in these resting cells was observed when suspensions were exposed to a diurnal pattern of illumination rather than continuous light. Although nitrogenase function and synthesis are closely coupled to photosynthetic activity, the biosyntheses of bacteriochorophyll and nitrogenase are independent of each other and are most probably subject to different regulatory mechanisms by light.

Nitrogen fixation and hydrogen metabolism in photosynthetic bacteria.

The photosynthetic bacteria are found in a wide range of specialized aquatic environments. These bacteria represent important members of the microbial community since they are capable of carrying out two of the most important processes on earth, namely, photosynthesis and nitrogen fixation, at the expense of solar energy. Since the discovery that these bacteria could fix atmospheric nitrogen, there has been an intensification of studies relating to both the biochemistry and physiology of this process. The practical importance of this field is emphasized by a consideration of the tremendous energy input required for the production of artificial nitrogenous fertilizer. The present communication aims to briefly review the current state of knowledge relating to certain aspects of nitrogen fixation by the photosynthetic bacteria. The topics that will be discussed include a general survey of the nitrogenase system in the various photosynthetic bacteria, the regulation of both nitrogenase biosynthesis and activity, recent advances in the genetics of the nitrogen fixing system, and the hydrogen cycle in these bacteria. In addition, a brief discussion of some of some of the possible practical applications provided by the photosynthetic bacteria will be presented.

Utilization of 35S-thiosulphate and an appraisal of the role of ATP-sulphurylase in chemolithotrophic Thiobacillus ferrooxidans.

Differentially labelled 35S-thiosulphate was taken up by washed cells of Thiobacillus ferrooxidans which were previously grown on thiosulphate. The uptake was proportional to the biomass over the range 0.5-4.0 mg dry wt. of bacteria and showed typical saturation kinetics with an estimated Km value of 0.5 mM for 35S-thiosulphate. Dithionate and Group VI anions inhibited the uptake, which was under pH control and had a temperature optimum of 50 degrees C. In the absence of thiosulphate, the cells bound 35S-sulphate but the binding did not increase on prolonged incubation and the label could be removed completely by washing with dilute sulphuric acid. Increasing amounts of the label were incorporated from [outer-35S]thiosulphate into cellular materials over a 60-min period, whereas little or no assimilation was observed from either the [inner-35S]thiosulphate or 35S-sulphate. The kinetic properties of the sulphate-activating enzyme ATP-sulphurylase enriched from bacteria grown with either thiosulphate or ferrous-iron were similar although this enzyme has an assimilatory function only when the bacterium is grown with ferrous-iron.