Biomedical subjects
John A Baker
Publications and source records attributed to John A Baker.
Nursing attitudes towards acute mental health care: development of a measurement tool.
AIM: This paper reports the development, piloting and validation of a tool to measure attitudes for use with nursing staff working in acute mental health care units. BACKGROUND: The quality of care provided for service users in acute mental health care has come under both scrutiny and severe criticism. The attitudes of staff working in these environments have been cited as a contributory factor in poor care. No measure of attitudes specific to acute mental health has been reported. METHODS: A 64-question measure was constructed and distributed to a sample of qualified and unqualified nurses drawn from seven mental health care units in the North of England. Exploratory factor analysis and a number of other statistical tests were performed to validate the questionnaire. RESULTS: Preliminary analysis reduced the original 64 questions to 37. Five components were retained, accounting for 42% of the variance, and the five rotated factors were identified. The resultant 'Attitudes Towards Acute Mental Health Scale' (ATAMHS) achieved good internal reliability, with a Cronbach's alpha of 0.72. CONCLUSION: The construction and validation of the ATAMHS measure will enable improved understanding of the attitudes of nursing staff working in acute mental health care settings to occur. This measure is available for use in a clinical area of nursing in which attitude change is of fundamental importance for future development of care.
Cognitive behaviour therapy within acute mental health care: a critical appraisal.
This paper examines the evidence for the use of cognitive behavioural therapy (CBT) within acute mental health-care settings. Through the provision of a literature review the authors critique the research into the effectiveness of CBT when delivered within acute mental health-care settings, to clients who are acutely psychotic. The review concludes with recommendations for future research to expand the current evidence base.
Evolution in parallel: new insights from a classic system.
Neo-darwinists have long argued that parallel evolution, the repeated evolution of similar phenotypes in closely related lineages, is caused by the action of similar environments on alleles at many loci of small effect. A more controversial possibility is that the genetic architecture of traits initiates parallelism, sometimes through fixation of alleles of large effect. Recent research (by Cole et al., Colosimo et al., Cresko et al., and Shapiro et al.) offers the surprising insight that reduction in two armor traits of threespine stickleback is governed by independently segregating major loci as well as additional quantitative trait loci (QTL), and that alleles at the same major loci are associated with parallel phenotypes in globally distributed populations. This research suggests the emergence of a new and exciting vertebrate model system for evolutionary genetics.
The use of isotopes to identify landfill gas effects on groundwater.
An evaluation of the source of volatile organic compounds in groundwater samples was performed at a landfill in southern California. The 3H (tritium) content of the water in leachate and water from the gas-collection system (condensed water and entrained water droplets) and the delta 13C and 14C content of the inorganic carbon in landfill gas CO2, leachate, and gas-collection system water were used to characterize the dissolved inorganic carbon (DIC) inside the landfill, while the same parameters were monitored in groundwater samples from affected monitoring wells and an unaffected well. Tritium levels from leachate and gas-collection system condensate ranged from approximately 2000 TU to over 4000 TU, orders of magnitude higher than unaffected groundwater. The average 14C content of DIC in the landfill pore-water samples was 121 pMC and the 14C content of unaffected groundwater DIC was 93 pMC, while the 14C content of the dissolved inorganic carbon in groundwater with VOC detections ranged from 105 to 119 pMC. The delta 13C of DIC in pore water was consistently above 0 per thousand and the delta 13C of unaffected groundwater DIC was -20.3 per thousand, while the delta 13C of DIC in affected groundwater samples was increased from -17.3 to -13.2 per thousand. The increases in both delta 13C and 14C in landfill gas-impacted groundwater DIC generally correlated with the number of volatile organic compounds detected and their concentrations. Based on the tritium and DIC 14C levels in leachate and water from the gas-collection system compared to those of unaffected water, significant increases in the tritium content of the water would be expected to accompany VOC detections and increases in delta 13C and 14C caused by landfill water. The results rule out landfill water as the VOC source, leaving landfill gas as the source. The identities and concentrations of the specific VOCs in affected groundwater samples varied among wells as well as between two leachate samples, ruling out the use of a VOC "fingerprint" for leachate or landfill gas to be compared to groundwater VOC concentrations.
Reduction of egg size in natural populations of threespine stickleback infected with a cestode macroparasite.
Manifestations of infectious disease may represent host adaptations to avoid or reduce the effects of infection on host fitness, parasite manipulations that benefit the pathogen's fitness, or nonadaptive side effects of parasitism. Threespine stickleback fish (Gasterosteus aculeatus) from Alaska and the cestode macroparasite Schistocephalus solidus provide an excellent system for study of the effects of parasitism on host egg size because females in populations there are capable of producing clutches of eggs in the face of substantial infection, contrary to the inhibition of reproduction that has been observed in other stickleback populations or other species of fish. A side effect resulting in reduction of mean ovummass among infected females was predicted based on the egg production process in female stickleback, the considerable energy and resource demands of S. solidus, and the chronic and progressive nature of the effects the macroparasite should have on the host fish. In each of 9 populations of G. aculeatus representing replicate natural experiments in lakes scattered across the Matanuska-Susitna Valley and the Kenai Peninsula of south-central Alaska and among all populations combined, the mean ovum mass of infected female fish is significantly reduced in comparison with that of uninfected females taken from the same population at the same time. Reduction in mean female egg mass ranged from 8 to 32% across all populations. To examine whether reduction in mean female ovum mass was a nonadaptive side effect or an adaptation, relatively large data sets from 2 of the populations were used. Mean ovum mass of infected females was predicted to decrease directly in relation to parasite index (PI) if the diminution in mean egg mass were the result of a nonadaptive side effect resulting from host nutrient loss. Alternatively, the absence of a relationship between PI and reduction in ovum mass is predicted if decreases in mean female ovum mass result from host or parasite adaptation (or both) because lightly infected hosts should show a response similar to that of heavily infected ones. In each of the 2 populations, there is a significant, negative relationship between mean female ovum mass and PI, demonstrating a correlation between the decrease in ovum mass and the level of infection. Thus, the results are consistent with the hypothesis that the reductions in mean female egg mass represent side effects of parasitism involving nutrient theft. Moreover, the proportional decline in egg mass with increasing PI apparently differed between the 2 populations, and there was no significant relationship between mean percent decrease in mean female ovum mass and mean PI across populations. These observations suggest that unknown ecological and evolutionary factors influence the degree of reduction in mean ovum mass in a population-specific manner.
The "crowding effect" in the cestode Schistocephalus solidus: density-dependent effects on plerocercoid size and infectivity.
The occurrence of the crowding effect was demonstrated in plerocercoids of the cestode Schistocephalus solidus infecting threespine stickleback Gasterosteus aculeatus from Walby and Scout lakes, Alaska. Contrary to an earlier report, relatively large numbers of parasites (>3-4 plerocercoids) were observed to grow large enough in an intermediate host fish to become competent to infect and to mature in the definitive host under any of 3 assumed threshold values and 1 scenario of graded sizes for parasite competency. In Walby Lake, intensity and host body mass were significant predictors of mean plerocercoid mass per host, whereas intensity, host body mass, and combined parasite index were significant predictors in Scout Lake. Slopes of equations expressing the relationship between mean parasite mass and intensity for both lakes were less than 1, implying that processes other than or in combination with simple resource limitation might be producing the observed crowding effect. The causal mechanism for the crowding effect could include exploitative competition, interference competition, and host immune response. There were significant differences in infection between the two lakes, including different distributions of parasite intensities among hosts and different expressions of the crowding effect; however, an explanation of the differences awaits further investigation.
The prevalence of asymptomatic Chlamydia trachomatis in military dependent adolescents.
Chlamydia trachomatis infection is common among sexually active populations and often asymptomatic. Infection is associated with complications, including pelvic inflammatory disease and infertility. Using a noninvasive urine ligase chain reaction assay, we determined the prevalence of asymptomatic C. trachomatis infection among sexually active military dependent adolescents and young adults attending clinics at military facilities in San Antonio. The overall prevalence rate was 14%, higher than that reported in many high-risk settings, including sexually transmitted disease clinics. Gender-specific rates were 15% for females and 11% for males. Given a clear cost benefit to screening and treating at-risk populations, we conclude that screening of all sexually active military dependents, both male and female, using this noninvasive test should be performed routinely.