Life-history plasticity in female threespine stickleback.

The postglacial adaptive radiation of the threespine stickleback fish (Gasterosteus aculeatus) has been widely used to investigate the roles of both adaptive evolution and plasticity in behavioral and morphological divergence from the ancestral condition represented by present-day oceanic stickleback. These phenotypes tend to exhibit high levels of ecotypic differentiation. Population divergence in life history has also been well studied, but in contrast to behavior and morphology, the extent and importance of plasticity has been much less well studied. In this review, we summarize what is known about life-history plasticity in female threespine stickleback, considering four traits intimately associated with reproductive output: age/size at maturation, level of reproductive effort, egg size and clutch size. We envision life-history plasticity in an iterative, ontogenetic framework, in which females may express plasticity repeatedly across each of several time frames. We contrast the results of laboratory and field studies because, for most traits, these approaches give somewhat different answers. We provide ideas on what the cues might be for observed plasticity in each trait and, when possible, we inquire about the relative costs and benefits to expressed plasticity. We end with an example of how we think plasticity may play out in stickleback life history given what we know of plasticity in the ancestor.

Iterative development and the scope for plasticity: contrasts among trait categories in an adaptive radiation.

Phenotypic plasticity can influence evolutionary change in a lineage, ranging from facilitation of population persistence in a novel environment to directing the patterns of evolutionary change. As the specific nature of plasticity can impact evolutionary consequences, it is essential to consider how plasticity is manifested if we are to understand the contribution of plasticity to phenotypic evolution. Most morphological traits are developmentally plastic, irreversible, and generally considered to be costly, at least when the resultant phenotype is mis-matched to the environment. At the other extreme, behavioral phenotypes are typically activational (modifiable on very short time scales), and not immediately costly as they are produced by constitutive neural networks. Although patterns of morphological and behavioral plasticity are often compared, patterns of plasticity of life history phenotypes are rarely considered. Here we review patterns of plasticity in these trait categories within and among populations, comprising the adaptive radiation of the threespine stickleback fish Gasterosteus aculeatus. We immediately found it necessary to consider the possibility of iterated development, the concept that behavioral and life history trajectories can be repeatedly reset on activational (usually behavior) or developmental (usually life history) time frames, offering fine tuning of the response to environmental context. Morphology in stickleback is primarily reset only in that developmental trajectories can be altered as environments change over the course of development. As anticipated, the boundaries between the trait categories are not clear and are likely to be linked by shared, underlying physiological and genetic systems.

Platinum stable isotope analysis of geological standard reference materials by double-spike MC-ICPMS.

We report a method for the chemical purification of Pt from geological materials by ion-exchange chromatography for subsequent Pt stable isotope analysis by multiple-collector inductively coupled plasma mass spectrometry (MC-ICPMS) using a 196Pt-198Pt double-spike to correct for instrumental mass bias. Double-spiking of samples was carried out prior to digestion and chemical separation to correct for any mass-dependent fractionation that may occur due to incomplete recovery of Pt. Samples were digested using a NiS fire assay method, which pre-concentrates Pt into a metallic bead that is readily dissolved in acid in preparation for anion-exchange chemistry. Pt was recovered from anion-exchange resin in concentrated HNO3 acid after elution of matrix elements, including the other platinum group elements (PGE), in dilute HCl and HNO3 acids. The separation method has been calibrated using a precious metal standard solution doped with a range of synthetic matrices and results in Pt yields of ≥90% with purity of ≥95%. Using this chemical separation technique, we have separated Pt from 11 international geological standard reference materials comprising of PGE ores, mantle rocks, igneous rocks and one sample from the Cretaceous-Paleogene boundary layer. Pt concentrations in these samples range from ca. 5 ng g-1 to 4 µg g-1. This analytical method has been shown to have an external reproducibility on δ198Pt (permil difference in the 198Pt/194Pt ratio from the IRMM-010 standard) of ±0.040 (2 sd) on Pt solution standards (Creech et al., 2013, J. Anal. At. Spectrom. 28, 853-865). The reproducibility in natural samples is evaluated by processing multiple replicates of four standard reference materials, and is conservatively taken to be ca. ±0.088 (2 sd). Pt stable isotope data for the full set of reference materials have a range of δ198Pt values with offsets of up to 0.4‰ from the IRMM-010 standard, which are readily resolved with this technique. These results demonstrate the potential of the Pt isotope system as a tracer in geochemical systems.

Rapid shifts in multiple life history traits in a population of threespine stickleback.

Measurement of the rate of phenotypic or genetic change provides data bearing on many questions of fundamental interest to biologists, including how fast changes can proceed, whether shifts occur gradually or in bursts and how long high rates of change can be sustained. Because traits exist in functionally and genetically correlated suites, studies tracking many traits are likely to be the most informative. We quantify very rapid phenotypic changes in egg size (now smaller), clutch size (larger) and the age/size of both breeding females and males (younger, smaller) in an Alaskan population, with these traits shifting at rates from 0.13 to 0.30 haldanes over a 10-year period. In contrast, female reproductive effort and the allometric relationship of clutch size to body size changed little. These shifts appear to be caused by an altered selective landscape, with the presumed selective agent being increasing lake productivity. Some of the traits undoubtedly have at heritable component and thus represent genetic evolution as well as phenotypic.

Host mortality and variability in epizootics of Schistocephalus solidus infecting the threespine stickleback, Gasterosteus aculeatus.

SUMMARY: An analysis of the metrics of Schistocephalus solidus infection of the threespine stickleback, Gasterosteus aculeatus, in Walby Lake, Alaska, showed that an epizootic ended between 1996 and 1998 and another occurred between 1998 and 2003. The end of the first epizootic was associated with a crash in population size of the stickleback, which serves as the second intermediate host. The likely cause of the end of that epizootic is mass mortality of host fish over winter in 1996-1997. The deleterious impact of the parasite on host reproduction and increased host predation associated with parasitic manipulation of host behaviour and morphology to facilitate transmission might also have played a role, along with unknown environmental factors acting on heavily infected fish or fish in poor condition. The second epizootic was linked to relatively high levels of prevalence and mean intensity of infection, but parasite:host mass ratios were quite low at the peak and there were no apparent mass deaths of the host. A number of abiotic and biotic factors are likely to interact to contribute to the occurrence of epizootics in S. solidus, which appear to be unstable and variable. Epizootics appear to depend on particular and, at times, rare sets of circumstances.

The impact of a good practice manual on professional practice associated with psychotropic PRN in acute mental health wards: an exploratory study.

BACKGROUND: As required or pro re nata (PRN) psychotropic medicines are frequently used in acute mental health wards. PRN is known to contribute to polypharmacy and high doses of antipsychotic medication. Few studies have attempted to improve clinician's use of these potentially harmful drugs. AIMS: The objectives of the study were to determine the impact and acceptability of a good practice manual on prescribing and administration practices of PRN psychotropic medication in acute mental health wards. DESIGN: The study used a pre-post exploratory design with two acute mental health wards in the NW of England. RESULTS: Over the total trial period of 10 weeks, 28 of 35 patients received 484 doses of PRN. Patients had a mean of 3.6 prescriptions of 14 different PRN medications in 34 different dose combinations prescribed. Medication errors beyond poor quality of prescribing occurred in 23 of the 35 patients (65.7%). Prescription quality improved following the introduction of the intervention but quality of nursing notes reduced. Acceptability of the manual to both nursing and medical staff was high. CONCLUSION: The introduction of the manual appeared to influence some of the practices associated with the prescribing and administration of PRN psychotropic medications. Further, larger, more robust studies are required in this area. In particular research is required to identify the reasons why professionals continue to rely so heavily on using PRN medication.

Surveying the attitudes of acute mental health nurses.

Recent UK policy and guidance indicates the importance of positive attitudes towards mental health service users. This is especially true in acute inpatient care, where service users are often at their most vulnerable and have higher levels of contact with mental health staff. The following paper details secondary analysis of data collected for the validation of an attitude measurement scale with a sample of 140 nursing staff in acute settings. The results demonstrate that a wide range of attitudes are held by mental health nurses towards acute mental health care. Overall, the results indicate generally positive attitudes. Significant differences were found between qualified and unqualified staff, and males and females for some questions. Recommendations are made for future attitudinal research of mental health staff.

Multidisciplinary consensus of best practice for pro re nata (PRN) psychotropic medications within acute mental health settings: a Delphi study.

There is a limited evidence base for the use of pro re nata (PRN) 'as required' psychotropic medication within acute mental health settings. This study aimed to explore expert opinion concerning issues and best practice for the prescribing and administration of psychotropic PRN medications within acute inpatient mental health settings. Eighteen experts participated in three Delphi rounds of a modified Delphi panel to establish consensus. A total of 271 items were initially generated from four questions. As a result of the consensus process the number of items retained reduced to 78, then 34 items and finally 13 items. Clinicians' practice could be informed by the 13 recommendations established by the Delphi panel. Further research is required to establish the clinical effectiveness of these recommendations.

Timing of Infections in the Threespine Stickleback (Gasterosteus aculeatus) by Schistocephalus solidus in Alaska.

This study provides direct evidence for the timing of infections by Schistocephalus solidus in the threespine stickleback (Gasterosteus aculeatus) of south-central Alaska. Young-of-the-year fish in Cheney Lake were infected during their first summer within a few months after hatching in May-June. Infections appear to continue under ice cover on the lake during the subsequent fall and winter. Few, if any, 1-yr-old fish seemed to be infected for the first time, although 1-yr-old hosts with established parasites apparently acquired additional infections.

Lipid and salt effects on carbocyanine dye-induced photo-voltages in bilayer membranes.

Voltage transients induced by flash illumination of bilayer membranes with sorbed dye, 3,3' -dimethyl-2,2' -oxacarbocyanine chloride (diO-C1-3-CI), vary with membrane lipid composition and aqueous solution salt concentration. The voltage transients are probably induced by physical movements of sorbed dye molecules following photo-isomerization. Increased salt (NaCl and NaBr) concentrations in the aqueous solutions reduced the photo-voltage amplitudes by reducing the amount of dye sorbed to the membranes, and by decreasing the effective membrane thickness. The photo-voltage risetimes and falltimes varied systematically with salt concentration and membrane lipid composition, reflecting structural changes in the membrane's surface layer.

Organizing and delivering training for acute mental health services: a discussion paper.

Recent policy statements that address the quality of care provided by acute mental health services have highlighted an urgent need for specialist nurse education and training. However, examples of how to design and implement such training initiatives are sparse. Drawing on recent experience of developing an innovative training programme for acute psychiatric settings, this paper seeks to examine some of the key issues associated with current training provision for acute inpatient mental health workers. The methodological and practical concerns surrounding this type of initiative are discussed with the main aspects of programme content, service user participation, team training and organizational challenges being explored. Resulting from this work, several recommendations regarding the content, organization and delivery of future training initiatives are made.

Restoration of cognitive abilities by cholinergic grafts in cortex of monkeys with lesions of the basal nucleus of Meynert.

Three groups of marmosets were trained to perform a series of visual discrimination tasks in a Wisconsin General Test Apparatus. Two groups then received bilateral lesions of the basal nucleus of Meynert using the excitotoxin N-methyl-D-aspartate and were found to be severely impaired on relearning a visual discrimination first learnt prior to surgery. One lesioned group then received grafts of acetylcholine-rich tissue dissected from the basal forebrain of fetal marmosets. Three months later the marmosets with lesion alone remained impaired on a number of retention and reversal tasks whereas the transplanted animals were no longer significantly impaired. Histological examination of the brains indicated that all lesioned animals had sustained substantial loss of the cholinergic neurons of the basal nucleus of Meynert (assessed by nerve growth factor receptor immunoreactivity) and that the lesion-alone animals showed marked loss of the cholinergic marker acetylcholinesterase in the dorsolateral frontal and parietal cortex. All transplanted animals had surviving graft tissue (visualized by Cresyl Violet staining, dense acetylcholinesterase staining and the presence of a limited number of nerve growth factor receptor-immunoreactive neurons) in the neocortex and 5/6 transplanted animals showed near complete restitution of acetylcholinesterase staining in frontal and parietal cortex. Examination of individual animal data showed that the animal without this restitution performed very poorly. The performance of the remaining transplanted animals was significantly better than that of the animals with lesion alone. There was a significant positive correlation between the degree of acetylcholinesterase staining and good performance on tasks sensitive to frontal lobe damage. These results demonstrate that acetylcholine-rich tissue transplanted into the neocortex of primates with damage to the cholinergic projections to the neocortex can produce substantial restitution of function provided that an appropriate level of interaction between graft and host tissue is achieved.

The effect of metabolic milieu on cardiac PET imaging using fluorine-18-deoxyglucose and nitrogen-13-ammonia in normal volunteers.

Cardiac PET imaging using 13N-ammonia and 18FDG was performed on 17 normal volunteers in the glucose-loaded and fasted states. PET images (glucose-loaded and fasted) were subjected to qualitative visual analysis using the descriptors: image quality, FDG blood-pool activity, ammonia lung field activity, and clinical interpretability. Glucose-loaded studies had better image quality, diminished FDG blood-pool activity, and were more often clinically interpretable compared to fasted studies. Dietary state did not affect 13N-ammonia study parameters. Using a semi-quantitative region of interest method, 18FDG myocardial activity was homogeneous and significantly affected by dietary state (2.48 +/- 1.0 fold increase in myocardial-to-blood pool ratio in glucose-loaded versus fasted states). Serum glucose, insulin, and free-fatty acid concentrations responded physiologically to glucose loading and fasting but showed no correlation with myocardial 18FDG uptake. PET imaging using 13N-ammonia and 18FDG appears optimal in the glucose-loaded state.

Human pathologic correlation with PET in ischemic and nonischemic cardiomyopathy.

To assess the correlation between myocardial perfusion, metabolism and histologic findings in patients with cardiomyopathy, we evaluated myocardial perfusion and metabolism using positron emission tomography (PET) with 13NH3 (ammonia) and 18FDG (fluoro-2-deoxy-glucose) in nine patients prior to undergoing orthotopic cardiac transplantation. Four patients had ischemic cardiomyopathy (ISCM) and five had nonischemic cardiomyopathy (NISCM). Normalized circumferential profile analyses of representative mid-ventricular perfusion and metabolism PET images were performed for each patient. A corresponding mid-ventricular transaxial slice was obtained from the formalin fixed explanted heart and processed for routine histology. Hematoxylin-eosin stained and Masson trichrome stained sections were evaluated and the percentage of the slice occupied by infarct was determined planimetrically at 10-degree intervals in a circumferential manner. A significant correlation was found between circumferential normalized PET count density profile of perfusion and metabolism in both the ischemic and nonischemic groups (ISCM range r = 0.65-0.75; NISCM range, r = 0.70-0.87). Furthermore, there was a correlation in the ISCM group between the extent of matched perfusion/metabolism defects and transmural infarct involvement (r = 0.66-0.88). PET perfusion and metabolic data closely correlate with pathologic infarction in human hearts of ischemic cardiomyopathy patients.

Observer evaluation of scatter subtraction for digital portable chest radiographs.

RATIONALE AND OBJECTIVES: The authors compared standard digital portable chest radiographs (DPCXR) to scatter-subtracted DPCXR: METHODS: Thirty DPCXR were obtained using a photostimulable phosphor digital imaging system and a posterior beam stop (PBS) technique that allowed measurement of the scatter component of the DPCXR: The scatter component was subtracted from the clinical image to form a scatter-subtracted image. Six observers recorded preference for the standard image or scatter-subtracted image for identifying five radiographic landmarks and for image quality. RESULTS: A statistically significant preference was demonstrated for the scatter-subtracted images and for viewing the tracheo-bronchial tree, right paratracheal stripe, vertebral column, and support apparatus position. For unprocessed images, there was a statistically significant preference for viewing the pulmonary vasculature. No statistically significant preference was demonstrated for overall image quality. CONCLUSIONS: These results suggest that PBS scatter subtraction holds promise for improving visualization of structures in high-scatter regions of chest radiographs.

Posterior beam-stop method for scatter fraction measurement in digital radiography.

The authors presented a new posterior beam-stop (PBS) technique for measuring the ratio of scattered to total-detected photon flux (scatter fraction) in a radiographic examination while preserving the diagnostic quality of the image. The scatter measurement was made using a standard imaging geometry with both beam stops and an additional x-ray detector placed behind the standard imaging detector. This PBS geometry differs from the standard beam-stop (SBS) technique for scatter measurement. With SBS, a beam-stop shadow appears on the image. To evaluate the PBS technique, scatter fraction measurements were performed on an anatomic phantom using both the PBS and SBS techniques. When compared with the standard technique, PBS provided accurate estimation of scatter fractions. Since the measurement can be performed without degrading a standard clinical radiographic examination, the PBS technique allows simultaneous acquisition of scatter measurements from human patients in combination with a standard radiographic examination.

A comparison of immunofluorescent assays to detect anti-granulocyte antibodies.

Three immunofluorescent assays were compared to detect anti-granulocyte antibodies (AGA) in patients with immune disorders: the granulocyte immunofluorescence test (GIFT), the avidin-biotin coupling test (ABCT), and the modified staphylococcal protein A test (MSPAT). The ABCT was more sensitive than both the GIFT and MSPAT for patient sera, but it also detected more positivity among random normal sera. Although less sensitive than the ABCT, the GIFT and MSPAT showed greater specificity and higher predictive values for positivity. When normal lymphocytes were run in parallel with normal granulocytes, 68% of positive AGA sera were nonreactive with lymphocytes, indicating the antibody specificity for granulocytes. Comparison of three direct and indirect immunofluorescent assays suggested a general co-existence of both cell-bound and circulating AGA. However, the direct test displayed minimal amounts of fluorescence for negative controls in contrast to the variable levels of fluorescence seen in normal sera for the indirect test.

Biosynthesis of isoprenoids in Escherichia coli: stereochemistry of the reaction catalyzed by farnesyl diphosphate synthase.

[formula: see text] Farnesyl diphosphate (FPP) synthase from Escherichia coli catalyzes the condensation of isopentenyl diphosphate (IPP) and geranyl diphosphate (GPP) with selective removal of the pro-R hydrogen at C2 of IPP, the same stereochemistry observed for the pig liver, yeast, and avian enzymes.

Cognitive inflexibility after archicortical and paleocortical prefrontal lesions in marmosets.

The behaviour and cognitive abilities of marmosets with bilateral ablations of either the archicortex on the mediodorsal surface or the paleocortex on the ventrolateral surface of the frontal lobes were assessed in terms of the types of information being handled, the mode of action (inhibitory versus productive mechanisms), and the level of functioning of these frontal areas. Although there was a tendency for the ventrolateral ablation to produce a greater impairment on object than on spatial discrimination in comparison to the mediodorsal ablation, the differences between the two groups was not marked in this respect. The effect of ablations of either of these areas was more marked on tasks which required the inhibition of prepotent responses than on tasks where novel or arbitrary responses were appropriate. The major effect of both lesions was the production of perseverative behaviour which occurred at the level of motor output in the first few days after surgery but was then observed at the level of choice behaviour and attentional set in formal cognitive tests. Impairments were also seen on postoperative retention of tasks learnt prior to surgery. It is suggested that all these impairments arise from an inability to use or modify stored information.

An artificial neural network for estimating scatter exposures in portable chest radiography.

An adaptive linear element (Adaline) was developed to estimate the two-dimensional scatter exposure distribution in digital portable chest radiographs (DPCXR). DPCXRs and quantitative scatter exposure measurements at 64 locations throughout the chest were acquired for ten radiographically normal patients. The Adaline is an artificial neural network which has only a single node and linear thresholding. The Adaline was trained using DPCXR-scatter measurement pairs from five patients. The spatially invariant network would take a portion of the image as its input and estimate the scatter content as output. The trained network was applied to the other five images, and errors were evaluated between estimated and measured scatter values. Performance was compared against a convolution scatter estimation algorithm. The network was evaluated as a function of network size, initial values, and duration of training. Network performance was evaluated qualitatively by the correlation of network weights to physical models, and quantitatively by training and evaluation errors. Using DPCXRs as input, the network learned to describe known scatter exposures accurately (7% error) and estimate scatter in new images (< 8% error) slightly better than convolution methods. Regardless of size and initial shape, all networks adapted into radial exponentials with magnitude of 0.75, perhaps implying an ideal point spread function and average scatter fraction, respectively. To implement scatter compensation, the two-dimensional scatter distribution estimated by the neural network is subtracted from the original DPCXR.