STUDIES ON PATHOGENIC B. COLI FROM BOVINE SOURCES : II. MUTATIONS AND THEIR IMMUNOLOGICAL SIGNIFICANCE.

On agar plates certain strains of B. coli from the ileum of calves suffering from diarrhea or scours promptly mutate and give rise to forms which have lost capsular substance, whose virulence has been greatly reduced, and which have gained very greatly in agglutinability and in being taken up by leucocytes. The original characters are not regained in cultures kept in the cold after development, nor in rapid transfers in bouillon, nor in passages through the peritoneal cavity of guinea pigs. Filtrates of 48 hour bouillon cultures contain as much toxin in the (b) as in the (a) form indicating no loss in this function.     

Die Rosenmüllersche Grube als ätiologischer Faktor der Mittelohrentzündung

Ohne Zusammenfassung     

Static and dynamic compressive strains influence nitric oxide production and chondrocyte bioactivity when encapsulated in PEG hydrogels of different crosslinking densities

OBJECTIVE: Mechanical loading is an important regulator of chondrocytes; however, many of the mechanisms involved in chondrocyte mechanotransduction still remain unclear. Here, poly(ethylene glycol) (PEG) hydrogels are proposed as a model system to elucidate chondrocyte response due to cell deformation, which is controlled by gel crosslinking (rho(x)). METHODS: Bovine articular chondrocytes (50 x 10(6)cells/mL) were encapsulated in gels with three rho(x)s and subjected to static (15% strain) or dynamic (0.3 Hz or 1 Hz, 15% amplitude strain) loading for 48 h. Cell deformation was examined by confocal microscopy. Cell response was assessed by total nitric oxide (NO) production, proteoglycan (PG) synthesis ((35)SO(4)(2-)-incorporation) and cell proliferation (CP) ([(3)H]-thymidine incorporation). Oxygen consumption was assessed using an oxygen biosensor. RESULTS: An increase in rho(x) led to lower water contents, higher compressive moduli, and higher cell deformations. Chondrocyte response was dependent on both loading regime and rho(x). For example, under a static strain, NO was not affected, while CP and PG synthesis were inhibited in low rho(x) and stimulated in high rho(x). Dynamic loading resulted in either no effect or an inhibitory effect on NO, CP, and PG synthesis. Overall, our results showed correlations between NO and CP and/or PG synthesis under static and dynamic (0.3 Hz) loading. This finding was attributed to the hypoxic environment that resulted from the high cell-seeding density. CONCLUSION: This study demonstrates gel rho(x) and loading condition influence NO, CP, and PG synthesis. Under a hypoxic environment and certain loading conditions, NO appears to have a positive effect on chondrocyte bioactivity.     

Role of the N-terminal negative charges of actin in force generation and cross-bridge kinetics in reconstituted bovine cardiac muscle fibres

Mutant yeast actins were used to determine the role of actin's N-terminal negative charges in force generation. The thin filament was selectively removed from bovine cardiac skinned muscle fibres by gelsolin, and the actin filament was reconstituted from purified G-actin. In this reconstitution, yeast wild-type actin (2Ac: two N-terminal negative charges), yeast mutant actins (3Ac and 4Ac), and rabbit skeletal muscle actin (MAc) were used. The effects of phosphate, ATP and ADP on force development were studied at 25°C. With MAc, isometric tension was 77% of the initial tension owing to the lack of a regulatory system. With 2Ac, isometric tension was 10% of the initial tension; with 3Ac, isometric tension was 23%; and with 4Ac, isometric tension was 44%. Stiffness followed a similar pattern (2Ac < 3Ac < 4Ac < MAc). A similar trend was observed during rigor induction and relaxation. Sinusoidal analysis was performed to obtain the kinetic constants of the cross-bridge cycle. The results showed that the variability of the kinetic constants was ≤ 2.5-fold among the 2Ac, 4Ac and MAc muscle models. When the cross-bridge distribution was examined, there was no significant reapportionment among these three models examined. These results indicate that force supported by each cross-bridge is modified by the N-terminal negative charges of actin, presumably via the actomyosin interface. We conclude that two N-terminal negative charges are not adequate, three negative charges are intermediate, and four negative charges are necessary to generate force.     

Treating acute stress disorder: an evaluation of cognitive behavior therapy and supportive counseling techniques.

OBJECTIVE: Acute stress disorder permits an early identification of trauma survivors who are at risk of developing chronic posttraumatic stress disorder (PTSD). This study aimed to prevent PTSD by an early provision of cognitive behavior therapy. Specifically, this study indexed the relative efficacy of prolonged exposure and anxiety management in the treatment of acute stress disorder. METHOD: Forty-five civilian trauma survivors with acute stress disorder were given five sessions of 1) prolonged exposure (N = 14), 2) a combination of prolonged exposure and anxiety management (N = 15), or 3) supportive counseling (N = 16) within 2 weeks of their trauma. Forty-one trauma survivors were assessed at the 6-month follow-up. RESULTS: Fewer patients with prolonged exposure (14%, N = 2 of 14) and prolonged exposure plus anxiety management (20%, N = 3 of 15) than supportive counseling (56%, N = 9 of 16) met the criteria for PTSD after treatment. There were also fewer cases of PTSD in the prolonged exposure group (15%, N = 2 of 13) and the prolonged exposure plus anxiety management group (23%, N = 3 of 13) than in the supportive counseling group (67%, N = 10 of 15) 6 months after the trauma. Chronic PTSD in the supportive counseling condition was characterized by greater avoidance behaviors than in the prolonged exposure condition or the prolonged exposure plus anxiety management condition. CONCLUSIONS: These findings suggest that PTSD can be effectively prevented with an early provision of cognitive behavior therapy and that prolonged exposure may be the most critical component in the treatment of acute stress disorder.     

Encouraging smoking cessation among disadvantaged groups: a qualitative study of the financial aspects of cessation

Introduction and Aims. This study aimed to explore perceptions about financial aspects of smoking cessation among a group of disadvantaged welfare agency clients and their carers. Design and Methods. Qualitative focus groups and in‐depth interviews were supplemented with participant exit surveys about preferred smoking cessation strategies. Each discussion was audiotaped, transcribed and analysed using a thematic analysis. The setting was six non‐government community welfare service organisations operating in New South Wales, Australia. Eleven social services offered by these organisations participated. Thirty two clients participated in six client focus groups, 35 staff participated in six staff focus groups and eight manager telephone interviews were conducted. Results. Clients indicated that the cost of nicotine replacement therapy was a barrier to its use and that financial incentives were acceptable. Of the 16 possible strategies listed in the exit survey, the three selected as the most preferred by clients incorporated financial or non‐financial assistance. By contrast, staff and managers selected financial and non‐financial incentives as the least preferred and least feasible strategies. Discussion and Conclusions. The study found high acceptance of incentives as a smoking cessation strategy among a disadvantaged group of non‐government welfare service clients. The comparatively low level of desirability and feasibility from the perspective of service staff and managers suggests implementation of such an approach within the community service setting requires careful further testing.[Bonevski B, Bryant J, Paul C. Encouraging smoking cessation among disadvantaged groups: A qualitative study of the financial aspects of cessation. Drug Alcohol Rev 2011;30:411–418]     

From driverless dilemmas to more practical commonsense tests for automated vehicles

For the first time in history, automated vehicles (AVs) are being deployed in populated environments. This unprecedented transformation of our everyday lives demands a significant undertaking: endowing complex autonomous systems with ethically acceptable behavior. We outline how one prominent, ethically relevant component of AVs—driving behavior—is inextricably linked to stakeholders in the technical, regulatory, and social spheres of the field. Whereas humans are presumed (rightly or wrongly) to have the “common sense” to behave ethically in new driving situations beyond a standard driving test, AVs do not (and probably should not) enjoy this presumption. We examine, at a high level, how to test the common sense of an AV. We start by reviewing discussions of “driverless dilemmas,” adaptions of the traditional “trolley dilemmas” of philosophy that have sparked discussion on AV ethics but have limited use to the technical and legal spheres. Then, we explain how to substantially change the premises and features of these dilemmas (while preserving their behavioral diagnostic spirit) in order to lay the foundations for a more practical and relevant framework that tests driving common sense as an integral part of road rules testing.     

Post-traumatic stress disorder and traumatic brain injury: A review of causal mechanisms, assessment,and treatment

In this paper we explore the evidence for post-traumatic stress disorder (PTSD) after traumatic brain injury (TBI). We examine its possible mediating mechanisms after brain injury, the evidence for its occurrence, risk, and protective factors, and the implications for intervention and service demands. In the first section we review the current literature relevant to cause, maintenance, and treatment of PTSD in general, before addressing issues associated with the assessment and management of PTSD after TBI. It is argued that PTSD may occur after a brain injury, and can be, relatively, a common disorder. However, explanatory mechanisms for its occurrence may be speculative. In this context, we argue, assessment and treatment need to be carefully considered, and comprehensive.     

Caffeine affects cardiovascular and neuroendocrine activation at work and home

OBJECTIVE: This study investigated the effects of moderate doses of caffeine on ambulatory blood pressure and heart rate, urinary excretion of epinephrine, norepinephrine, and cortisol, and subjective measures of stress during normal activities at work and at home in the evening. METHODS: Healthy, nonsmoking, habitual coffee drinkers (N = 47) participated in 3 days of ambulatory study. After a day of ad lib caffeine consumption, caffeine (500 mg) and placebo were administered double-blind in counter-balanced order on separate workdays. Ambulatory blood pressure and heart rate were monitored from the start of the workday until bedtime. Urinary excretion of catecholamines and cortisol was assessed during the workday and evening. RESULTS: Caffeine administration significantly raised average ambulatory blood pressure during the workday and evening by 4/3 mm Hg and reduced average heart rate by 2 bpm. Caffeine also increased by 32% the levels of free epinephrine excreted during the workday and the evening. In addition, caffeine amplified the increases in blood pressure and heart rate associated with higher levels of self-reported stress during the activities of the day. Effects were undiminished through the evening until bedtime. CONCLUSIONS: Caffeine has significant hemodynamic and humoral effects in habitual coffee drinkers that persist for many hours during the activities of everyday life. Furthermore, caffeine may exaggerate sympathetic adrenal-medullary responses to the stressful events of normal daily life. Repeated daily blood pressure elevations and increases in stress reactivity caused by caffeine consumption could contribute to an increased risk of coronary heart disease in the adult population.