Variable fitness effects of Wolbachia infection in Drosophila melanogaster.

Maternally inherited Wolbachia bacteria are extremely widespread among insects and their presence is usually associated with parasitic modifications of host fitness. Wolbachia pipientis infects Drosophila melanogaster populations from all continents, but their persistence in this species occurs despite any strong parasitic effects. Here, we have investigated the symbiosis between Wolbachia and D. melanogaster and found that Wolbachia infection can have significant survival and fecundity effects. Relative to uninfected flies, infected females from three fly strains showed enhanced survival or fecundity associated with Wolbachia infection, one strain showed both and one strain responded positively to Wolbachia removal. We found no difference in egg hatch rates (cytoplasmic incompatibility) for crosses between infected males and uninfected females, although there were fecundity differences. Females from this cross consistently produced fewer eggs than infected females and these fecundity differences could promote the spread of infection just like cytoplasmic incompatibility. More surprising, we found that infected females often had the greatest fecundity when mated to uninfected males. This could also promote the spread of Wolbachia infection, though here the fitness benefits would also help to spread infection when Wolbachia are rare. We suggest that variable fitness effects, in both sexes, and which interact strongly with the genetic background of the host, could increase cytoplasmic drive rates in some genotypes and help explain the widespread persistence of Wolbachia bacteria in D. melanogaster populations. These interactions may further explain why many D. melanogaster populations are polymorphic for Wolbachia infection. We discuss our results in the context of host-symbiont co-evolution.

Social control agents or front-line carers for people with mental health problems: police and mental health services in Sydney, Australia.

The relationship between mental health services and police and people who have mental health problems, are suicidal or are drug- and/or alcohol-affected is examined in this paper. A survey of 131 police officers in Sydney, Australia, revealed that more than 10% of police time is spent dealing with people with mental health problems. Nevertheless, police felt unsupported in this role, unprepared for it and torn between the competing demands experienced in their work. A lack of confidence in dealing with suicidal people and a belief that work with mentally disturbed people does not constitute valid police work are also reported. Managing people with mental disturbance is a major concern for police. Specifically, there are difficulties relating to: inadequate training and education; deficiencies in services/resources; time and resource over-utilization; communication, liaison and feedback problems, and frustration related to accessing mental health facilities/services. It is argued that police work involving mentally disturbed people is a valid and necessary role that complements law enforcement. In order to facilitate this aspect of police work, recommendations are made regarding education and collaborative working relationships between police and mental health professionals, which, in turn, could improve the care of mentally disturbed people in the community.

Geographic analysis of nucleotide diversity and song sparrow (Aves: Emberizidae) population history.

Mitochondrial DNA (mtDNA) control-region (CR) sequences were analysed to address three questions regarding the evolution of geographical variation in song sparrows. (i) Are mtDNA sequences more informative about phylogenetic relationships and population history than previously published restriction fragment (RFLP) data? (ii) Are song sparrow CR sequences evolving in a selectively neutral manner? (iii) What do the haplotype cladogram and geographical pattern of nucleotide diversity (pi) suggest about the recent evolutionary history of song sparrow populations? Results from phylogenetic analyses of CR sequences corroborate RFLP results and reveal instances in which haplotypes do not group by locality. Neutrality tests (Tajima 1989a) suggest that song sparrow mtDNA is evolving in a selectively neutral manner, although exceptions are noted. A novel geographical pattern of pi suggests a model of song sparrow population history involving multiple Pleistocene refugia and colonization of some formerly glaciated regions from multiple sources. Moreover, application of coalescence theory to the haplotype cladogram suggests that two different haplotypes (48NF and 151HA) may have predominated in different parts of the song sparrow's range. This model provides insight into the current distribution of song sparrow mtDNA haplotypes and may explain the discordance between evolutionary history inferred from mtDNA and morphology in this species.

FAD-mediated enzymatic conversion of NAD+ to NADH: application to chiral synthesis of L-lactate.

Electroenzymatic reduction of NAD+ to NADH for subsequent use in enzymatic synthesis has been carried out at carbon electrodes bearing lipoamide dehydrogenase (LiDH) immobilized under a Nafion film. The self-mediated electron transfer was made possible by an excess of flavin adenine dinucleotide (FAD) entrapped together with LiDH. Results were compared to those obtained with a similar electrode containing both LiDH and a polymeric form of FAD (pFAD) prepared by anodic polymerization of FAD.

Clinical evaluation is better: myoglobin estimation used singly as a discriminant for early acute myocardial infarction does not well identify patients who will benefit from thrombolytic therapy.

We have examined the use of serum myoglobin concentration in the management of cases of suspected acute myocardial infarction (AMI). In a series of 51 patients myoglobin, used as a discriminant, correctly identified 97% (28/29) of cases as AMI with one false positive. Initial clinical judgement based on history, examination and the electrocardiogram correctly identified 66% (19/29) of cases with one false positive. These patients were given streptokinase. However, in these further identified AMI patients, 78% (7/9) had small enzyme rises with non-Q wave infarction and/or non-ST elevation and therefore may not have benefited from thrombolytic therapy in contrast to the Q wave/raised ST segment infarcts with large enzyme rises identified by clinical means. Enthusiasm for myoglobin estimation, where used as a discriminant for AMI, as a direct pointer to thrombolysis in the early diagnosis of AMI should be tempered by this finding.

Culture and the self: implications for the perception of depression by Australian and Vietnamese nursing students.

The theoretical influence of self-concept on cognitive and emotional aspects of behaviour was tested in an exploratory survey of 187 Australian and Vietnamese student nurse participants. Symptoms of depression were depicted in either a family scenario or a context-free list and were rated for perceived depression utilizing the Hopkins Symptom Checklist-25 (HSCL-25). Narrative data were also obtained. Australians perceived significantly more depression than the Vietnamese who normalized the behaviours. There was a significant interaction between culture and the context of depression, whereby the Vietnamese, in contrast with the Australians, perceived greater depression in the family scenario than in the list. Thematic analysis of narrative data assisted interpretation by revealing Vietnamese themes of family and disruption of social harmony, philosophical and temporal approach to life and judgementalism. Australians were more focused on individual concerns such as psychological disturbance and the need for independence. Implications for transcultural nursing were drawn.

Transport of D-fructose and its analogues by Trypanosoma brucei.

Kinetic parameters for entry of D-fructose into Trypanosoma brucei brucei have been determined. The net uptake of D-fructose was found to be rapid and occurred at a rate which was comparable with that observed for uptake of D-glucose. The Km and Vmax were 3.91 +/- 1.58 mM and 69.1 +/- 7.2 nmol min-1 (mg protein)-1. D-Fructose was metabolized to pyruvate under aerobic conditions and to pyruvate and glycerol under anaerobic conditions in a manner similar to D-glucose. Comparisons of the kinetic parameters for D-fructose transport and metabolism indicated that uptake was rate limiting. Inhibition constants (Ki) for inhibition of 6-deoxy-D-glucose by D-fructose and D-fructose transport by 6-deoxy-D-glucose were consistent with the Km values for these two substrates. These interactions indicate that D-fructose and 6-deoxy-D-glucose share a single common transporter. 1,5-Anhydro-D-glucitol and 1,5 anhydro-D-mannitol (the fused pyranose ring analogues of D-glucose and D-mannose) have been found to interact well with the transporter, while L-sorbose (a D-fructose analogue with a pyranose ring) had only low affinity. However, 2,5-anhydro-D-mannitol (a fused furanose ring analogue of D-fructose) inhibited both 6-deoxy-D-glucose and D-fructose transport with a Ki of approx. 0.8 mM. The high affinity for 2,5-anhydro-D-mannitol (2-deoxy-D-fructofuranose) indicates that D-fructose is transported in the furanose ring form.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermoregulation during marathon running in cool, moderate, and hot environments.

A well-trained subject, age 38, ran continously for periods ranging from 60 to 165 min on a motor-driven treadmill at 255.7 m/min while confronted with an airflow equivalent to running speed in cool, moderate, and hot environments. After a period of intensive heat acclimatization, treadmill runs were repeated in the moderate and hot conditions. Measurements were also obtained outdoors in a competitive marathon race. Sweat rate (SR) and mean skin temperature (Ts) were linearly related to Tdb. Acclimatization did not alter VO2max or metabolic rate during the treadmill runs, but heart rat (HR),rectal temperature (Tre), and Ts were lower, SR was higher, and maximal run duration longer in the hot environment, postacclimatization. Maximum runs in the hot environment were terminated by a spiralling increase in Tre to hyperthermic levels, due largely to a marked reduction in cutaneous blood flow, probably reflecting cardiovascular overload from the combined muscular and thermoregulatory blood flow demands, coupled with the effects of progressive dehydration. Utilizing partitional calorimetry and the subject's metabolic heat production, two examples of limiting environmental conditions for his marathon running speed were given.