bdhA-patD operon as a virulence determinant, revealed by a novel large-scale approach for identification of Legionella pneumophila mutants defective for amoeba infection.

Legionella pneumophila, the causative agent of Legionnaires' disease, is an intracellular parasite of eukaryotic cells. In the environment, it colonizes amoebae. After being inhaled into the human lung, the bacteria infect and damage alveolar cells in a way that is mechanistically similar to the amoeba infection. Several L. pneumophila traits, among those the Dot/Icm type IVB protein secretion machinery, are essential for exploiting host cells. In our search for novel Legionella virulence factors, we developed an agar plate assay, designated the scatter screen, which allowed screening for mutants deficient in infecting Acanthamoeba castellanii amoebae. Likewise, an L. pneumophila clone bank consisting of 23,000 transposon mutants was investigated here, and 19 different established Legionella virulence genes, for example, dot/icm genes, were identified. Importantly, 70 novel virulence-associated genes were found. One of those is L. pneumophila bdhA, coding for a protein with homology to established 3-hydroxybutyrate dehydrogenases involved in poly-3-hydroxybutyrate metabolism. Our study revealed that bdhA is cotranscribed with patD, encoding a patatin-like protein of L. pneumophila showing phospholipase A and lysophospholipase A activities. In addition to strongly reduced lipolytic activities and increased poly-3-hydroxybutyrate levels, the L. pneumophila bdhA-patD mutant showed a severe replication defect in amoebae and U937 macrophages. Our data suggest that the operon is involved in poly-3-hydroxybutyrate utilization and phospholipolysis and show that the bdhA-patD operon is a virulence determinant of L. pneumophila. In summary, the screen for amoeba-sensitive Legionella clones efficiently isolated mutants that do not grow in amoebae and, in the case of the bdhA-patD mutant, also human cells.

In vitro activities of fourteen antimicrobial agents against obligately anaerobic bacteria.

The in vitro activities of fourteen antimicrobial agents were tested against 292 clinical isolates of obligately anaerobic bacteria using the broth microdilution technique. Taking all strains as a group the MIC(50/90) (mg/l) values were metronidazole and imipenem 0.25/1, meropenem 0.25/0.5, trovafloxacin 0.25/1, gatifloxacin and moxifloxacin 0.5/2, levofloxacin 2/16, ciprofloxacin 4/32, clindamycin 0.5/8, amoxycillin/clavulanate 1/4, doxycycline and chloramphenicol 2/4, erythromycin 4/>32 and penicillin G 16/>32.

Clarifying the concept of critical thinking in nursing.

Nursing must chart a course between the pedagogical extremes of process versus content-focused courses. No one would deny the fact that nurses must have a solid knowledge base in addition to demonstrating an ability to think critically. Reason favors a "both-and" rather than an "either-or" approach to this issue. Justifiably, nurses have jumped on the bandwagon of critical thinking. Once on the bandwagon, however, the elusive butterfly of critical thinking has been difficult to net. It is time to inform the driver that a new course for nursing must be charted. So far, the reported nursing research has focused on critical thinking conceptualized as a score on a broad, objective test. The important first step of establishing a clear concept that defines critical thinking in nursing has not been accomplished. Finding out what the expert nurse does with knowledge will help us to articulate a conception of critical thinking that can then be used as a springboard for various teaching strategies. If educators are persuaded that "students can and should think their way through the content of their courses, can and should gain some grasp of the logic of what they study, can and should develop explicit intellectual standards, then they can find many ways to move instruction in this direction" (Barnes, 1992, p. 22).

Spiral processes of becoming: women's experiences within the context of doctoral education.

The purpose of this qualitative study was to explore women's experiences of being a doctoral student. We report on interviews from 11 women, 8 of whom were Caucasian and 3 of whom were African-American. Participants in the study described their experiences as doctoral students in ways that reflected a spiraling process of becoming. This process included experiences of confidence, support and self-discovery. This research has implications for nursing faculty and women engaged in doctoral education as well as for women who anticipate entering doctoral programs.

Social policy as a cause of childhood accidents: the children of lone mothers.

Almost one in five British mothers is a lone mother. Their children have injury rates that are twice those of children in two parent families. In this article the link between lone parenthood and childhood injury is examined. The increased injury rates for the children of lone mothers can be explained by the poverty, poor housing conditions, and social isolation of lone mothers in Britain. The problem of reconciling the demands of paid work with the demands of the unpaid work of childrearing is particularly difficult for lone mothers, who find themselves in a benefit dependent poverty trap. Many such mothers would seek paid work if affordable day care were available. Day care would also provide a safe environment for their children, who are otherwise exposed to the environmental hazards of poor housing. Provision of day care is a social policy that would have important effects on the health and welfare of lone mothers and their children. These effects deserve to be properly evaluated.

Physical health measurement of the older adult: new instrumentation.

The Georgia Centenarian Study examines the biologic, psychologic, and social factors contributing to life satisfaction and successful aging in late adulthood. Three age groups are included, 60 through 69 years, 80 through 89 years, and 100+ years. While the overall theoretical model includes multiple variables, physical health is viewed as critical to successful aging. This article presents an overview of physical health measurement for older persons. Some existing measures of physical health are included in the test battery for the Georgia Centenarian Study; however, the investigators determined the need for the inclusion of a new instrument. This article describes existing measures as well as the rationale and process of development of a new instrument.

Risk compensation in children's activities: A pilot study.

BACKGROUND: The intent of protective equipment (PE) in sports and leisure activities is to reduce injuries. However, some postulate that any safety measure prompts riskier behaviour, a phenomenon known as 'risk homeostasis' or 'risk compensation.' This study explores one approach to examining this in children. The rationale for this pilot study was to establish if children between six and 16 years old could answer questions about risk-taking sensibly and which questions, if any, could be eliminated; to establish the reliability of response; and to determine the numbers needed for a definitive study. METHODS: Sixty-three children with nonsevere injuries, ages six to 16 years, were interviewed while waiting to be seen at the Montreal Children's Hospital emergency department. An interviewer administered a questionnaire comprising three sections. The first part only applied to those who were injured in an activity for which some form of PE was available (n=19). The second part examined customary risk-taking behaviour using the thrill and adventure seeking scales of a standardized questionnaire (Zuckerman) (n=63). The third section posed hypothetical questions about likely risk-taking when using PE to those who had engaged in such activities (n=58). RESULTS: The approach and questionnaire proved feasible with this age group. The responses suggest that children wearing PE were more likely to report increased risk-taking than those who did not wear PE. For most of the hypothetical questions, the majority also reported changes toward riskier behaviour when using PE. However, those wearing PE scored lower on the thrill and adventure seeking scale, suggesting that they are, by nature, less venturesome. CONCLUSION: The results indicate that risk compensation may modify the effectiveness of PE for children engaged in sports and leisure activities. Conversely, the findings also suggest that those wearing PE may be a cautious subgroup.

Influence of viewing professional ice hockey on youth hockey injuries.

INTRODUCTION: Most televised National Hockey League (NHL) games include violent body checks, illegal hits and fights. We postulated that minor league players imitated these behaviours and that not seeing these games would reduce the rate of injuries among younger hockey players. METHODS: Using a quasi-experimental design, we compared 7 years of televised NHL matches (2002-2009) with the year of the NHL lock-out (2004/2005). Data from the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP) were used to identify the injuries and to ascertain whether they were due to intentional contact and illegal acts including fights. RESULTS: We found no significant differences in the proportions of all injuries and those involving intentional contact, violations or illegal acts among male minor league hockey players during the year when professional players were locked out and the years before and after the lock-out. CONCLUSION: We concluded that not seeing televised NHL violence may not reduce injuries, although a possible effect may have been obscured because there was a striking increase in attendance at equally violent minor league games during the lock-out.

The heterodimerization domains of MLL-FYRN and FYRC--are potential target structures in t(4;11) leukemia.

The chromosomal translocation t(4;11)(q21;q23) is a frequent genetic aberration of the mixed lineage leukemia (MLL) gene, predominantly associated with high-risk acute lymphoblastic leukemia (ALL) in pediatric patients. Previous studies demonstrated that mice transplanted with hematopoietic cells expressing the AF4-MLL fusion protein develop proB ALL. The AF4-MLL oncoprotein becomes activated by Taspase1-mediated hydrolysis, which subsequently leads to a heterodimer of the cleavage products AF4-MLL·N and MLL·C. This protein-protein interaction is due to the FYRN and FYRC interaction domains present in both protein fragments. Heterodimerization subsequently induces high-molecular-weight protein complex formation that is protected against SIAH1/2-mediated polyubiquitinylation. Here, we attempted to selectively block this initial heterodimerization step, aiming to prevent the oncogenic activation of the AF4-MLL multiprotein complex. The minimal interaction interface was experimentally defined first in a bacterial two-hybrid system, and then in mammalian cells by using a biosensor assay. Expression of the FYRC domain, or smaller portions thereof, resulted in the inhibition of heterodimer formation, and blocked AF4-MLL multiprotein complex formation with subsequent destruction of the AF4-MLL oncoprotein. Thus, it is in principle possible to specifically target the AF4-MLL protein. This knowledge can now be exploited to design inhibitory decoys in order to destroy the AF4-MLL oncoprotein.

Controlled trial of social work in childhood chronic illness.

Children with chronic illnesses have a doubled risk of becoming psychosocially maladjusted, and social-work support and counselling are commonly used to reduce this secondary morbidity. A randomised controlled trial of this type of intervention was conducted in 345 children with chronic physical disorders cared for in eleven specialty clinics at a children's hospital. Four months after a six-month period of social-work services, no significant difference was found between social-work and control groups in overall prevalence of maladjustment. There was no evidence to support a preventive or therapeutic effect of social work on child behaviour disorder or social dysfunction on the principal outcome measure, the Child Behaviour Checklist. Nor was there any detectable effect on child self-esteem, on maternal psychological function, or on the impact of the child's illness on the family. Furthermore, no patient subgroup could be shown to benefit from the intervention, and restriction of the analysis to individuals who received the intervention did not alter the results.

Discrimination of supraventricular tachycardia from sinus tachycardia of overlapping cycle length.

For more than 15 years, pulse generators (PG) have been implanted for the control of tachyarrhythmias. Manually activated systems have not achieved wide acceptance, mainly because of the need for direct patient participation. Automatic antitachycardia PGs have been limited by lack of flexibility of programmable parameters and the inability to discriminate pace-terminable tachycardias from sinus tachycardia. New algorithms for differentiating these tachycardias are becoming available. In addition to high rate detection criteria, there are three additional criteria that might characterize the tachycardias: (1) sudden onset, (2) rate stability, (3) sustained high rate. Future antitachycardia pacing systems will be able to employ even more elaborate algorithms when more sophisticated microprocessor capabilities and new sensors become available.

In vitro activities of gatifloxacin, two other quinolones, and five nonquinolone antimicrobials against obligately anaerobic bacteria.

The activity of the new fluoroquinolone gatifloxacin was compared with those of other quinolones and antimicrobial agents of other classes against 294 anaerobes by the broth microdilution technique. For all strains tested, gatifloxacin MICs at which 50 and 90% of the isolates were inhibited were 0.5 and 2 mg/liter, respectively, and were 3 to 4 dilution steps lower than, e.g., ciprofloxacin.

In vitro activity of telithromycin (HMR 3647) and seven other antimicrobial agents against anaerobic bacteria.

We assessed the in vitro activity of telithromycin (HMR 3647) and seven other antimicrobials against 292 strains of obligately anaerobic bacteria. MICs were determined with the microdilution technique and Wilkins-Chalgren broth according to DIN 58940-83. MIC50/MIC90s (mg/L) for telithromycin were 4/4 for Bacteroides fragilis, Bacteroides ovatus and Bacteroides thetaiotaomicron, 2/4 for Fusobacterium spp. and Bilophila wadsworthia, 2/2 for Bacteroides caccae, 1/4 for Bacteroides vulgatus, 0.25/4 for Prevotella spp., > or =0.03/0.5 for Clostridium spp. and 0.125/4 for Peptostreptococcus spp.