Density-mediated indirect effects from active predators and narrow habitat domain prey.

The hunting-mode-habitat-domain-range framework suggests that the mechanism driving trophic cascades (i.e., trait-mediated indirect interactions [TMIIs] vs. density-mediated indirect interactions [DMIIs]) should depend upon the functional traits of predators and prey. For example, trophic cascades containing active, broad habitat domain range (BHDR) predators interacting with narrow habitat domain range (NHDR) prey are predicted to arise primarily via TMIIs, because these prey should reduce their conspicuous activity in the presence of these predators. Unfortunately, this hypothesis is difficult to test given the strong bias against studies assessing trophic cascades containing NHDR prey. Furthermore, this hypothesis ignores evidence that (1) active predators can have high consumption rates on prey, (2) continuously responding to active predators foraging across broad areas is energetically costly for prey, and (3) cues from active, BHDR predators may not influence prey density. We examined the TMIIs and total indirect interaction (TII) produced during interactions between an active, BHDR ladybeetle predator (Naemia seriata) and its NHDR prey (scale insects). We exposed scale insects to nonlethal and lethal ladybeetle predators in laboratory mesocosms for 15 weeks. We measured the growth of the scale insect's host plant (cordgrass) and the population density of scale insects. Contrary to theory, nonlethal ladybeetles did not induce TMIIs. However, lethal ladybeetles increased cordgrass total and root dry biomass by 36% and 44%, respectively, suggesting the presence of strong DMIIs. Additionally, both lethal and nonlethal ladybeetles reduced scale insect population density. Our findings suggest that DMIIs, rather than TMIIs, can result from interactions between active BHDR predators and NHDR prey.

Huntington's disease cerebrospinal fluid seeds aggregation of mutant huntingtin.

Huntington's disease (HD), a progressive neurodegenerative disease, is caused by an expanded CAG triplet repeat producing a mutant huntingtin protein (mHTT) with a polyglutamine-repeat expansion. Onset of symptoms in mutant huntingtin gene-carrying individuals remains unpredictable. We report that synthetic polyglutamine oligomers and cerebrospinal fluid (CSF) from BACHD transgenic rats and from human HD subjects can seed mutant huntingtin aggregation in a cell model and its cell lysate. Our studies demonstrate that seeding requires the mutant huntingtin template and may reflect an underlying prion-like protein propagation mechanism. Light and cryo-electron microscopy show that synthetic seeds nucleate and enhance mutant huntingtin aggregation. This seeding assay distinguishes HD subjects from healthy and non-HD dementia controls without overlap (blinded samples). Ultimately, this seeding property in HD patient CSF may form the basis of a molecular biomarker assay to monitor HD and evaluate therapies that target mHTT.

Conspecifics, not pollen, reduce omnivore prey consumption.

Pollen can decrease (via reduced consumption) or increase (via numerical response) an omnivores consumption of animal prey. Although pollen can increase predation pressure through numerical responses of omnivores, pollen may also suppress predation by increasing omnivore interactions with conspecifics. Despite this potential, studies of the impacts of pollen on predation by omnivores often overlook the effect of these tissues on intraspecific interactions between omnivores. We designed three studies to examine how Spartina foliosa pollen and conspecific density impact scale insect prey consumption by ladybeetle (Naemia seriata) omnivores. First, we assessed how pollen impacts scale insect consumption by isolated ladybeetles. Second, we measured how pollen influences ladybeetle prey suppression when numerical responses were possible. Third, because initial experiments suggested the consumption rates of individual ladybeetles depended on conspecific density, we compared per capita consumption rates of ladybeetles across ladybeetle density. Pollen did not influence prey consumption by isolated ladybeetles. When numerical responses were possible, pollen did not influence total predation on prey despite increasing ladybeetle density, suggesting that pollen decreased per capita prey consumption by ladybeetles. The discrepancy between these studies is likely a consequence of differences in ladybeetle density-the presence of only two other conspecifics decreased per capita prey consumption by 76%. Our findings suggest that pollen may not alter the population level effects of omnivores on prey when omnivore numerical responses are offset by reductions in per capita predation rate.

Nonerosive reflux disease.

Nonerosive reflux disease (NERD) is the most common phenotype of gastroesophageal reflux disease. By definition, patients with NERD have typical reflux symptoms caused by the intraesophageal reflux of gastric contents but have no visible esophageal mucosal injury. This is in contrast to patients with erosive reflux disease (ERD) or Barrett's esophagus (BE) who have obvious esophageal mucosal injury on endosco-py. Only 50% of patients with NERD have pathologic esophageal acid exposure as detected on 24-h pH monitoring. NERD patients with physiologic esophageal acid exposure and good temporal correlation of symptoms with reflux events are considered to have esophageal hypersensitivity, while patients with no symptom-reflux correlation are considered to have functional heartburn. It is possible yet uncommon for NERD to progress to severe ERD (i.e. LA Grade C or D) or BE. Patients with NERD and pathologic esophageal acid exposure have motor dysfunction and acid reflux abnormalities that are similar to patients with ERD and BE, whereas NERD patients with physiologic esophageal acid exposure have minimal abnormalities and are not much different than healthy controls. The pathological feature most indicative of NERD is the presence of dilated intercellular spaces within squamous epithelium, an ultrastructural abnormality readily identified on transmission electron microscopy but also on light microscopy. A symptomatic response to an empiric trial of high-dose proton pump inhibitor (PPI) therapy is a simple and useful strategy to establish the diagnosis of NERD, although histology and pH monitoring may be useful in confirming the diagnosis. Patients with NERD suffer similar decrements in quality of life as do patients with erosive esophagitis. Therapy is aimed at eliminating or reducing symptoms and improving quality of life. PPIs are the most effective agents for the treatment of NERD although they are less effective in providing symptom relief than in patients with erosive esophagitis. Laparoscopic antireflux surgery is an effective therapy for selected patients with NERD and outcomes are better when performed in high volume centers.

Note: Self-biased voltage to suppress secondary electrons by a ZnO varistor in a compact pulsed neutron generator.

A large amount of back streaming electrons will bring about a part of current drain on power supply, cause sparking or high-voltage breakdowns, and affect the neutron yield and waveform for a compact sealed-tube pulsed neutron generator. A novel idea which uses a ZnO varistor to provide a constant self-biased voltage to suppress the secondary electrons is introduced. The I-V curve for the ZnO varistor was measured in the experiment. The effects of suppressing the secondary electrons were investigated using a ZnO varistor, linear resistors, and an independent power supply, respectively. The results show that the secondary electrons are suppressed effectively by the compact ZnO varistor, while not increasing the size and the component of the device. It is a promising design for compact sealed-tube neutron generators.

Involvement of dorsal striatal α1-containing GABAA receptors in methamphetamine-associated rewarding memories.

Rewarding memories induced by addictive drugs may contribute to persistent drug-seeking behaviors, which is an important contributing factor to drug addiction. However, the biological mechanisms underlying drug-associated rewarding memories have not yet been fully understood, especially the new synthetic drugs, such as amphetamine-type stimulants (ATS). In this study, using the rat-conditioned place preference (CPP) model, a classic animal model for the reward-associated effects of addictive drugs, we found that the expression level of GABAA α1 subunits was significantly decreased in the dorsal striatum (Dstr) after conditioned methamphetamine (METH) pairing, and no significant differences were observed in the other four rewarding memory-associated areas (medial prefrontal cortex (mPFC), nucleus accumbens (NAc), amygdala (Amy), and dorsal hippocampus (DH)). Intra-Dstr injection of either the GABAA receptor agonist muscimol or the specific α1GABAA receptor-preferring benzodiazepine (BDZ) agonist zolpidem significantly abolished METH CPP formation. Thus, this study extends previous findings by showing that GABAA receptors, particularly the α1-containing GABAA receptors, may be strongly implicated in METH-associated rewarding memories. This work provides us with a new perspective on the goal of treating ATS addiction.

Note: Triggering behavior of a vacuum arc plasma source.

Axial symmetry of discharge is very important for application of vacuum arc plasma. It is discovered that the triggering method is a significant factor that would influence the symmetry of arc discharge at the final stable stage. Using high-speed multiframe photography, the transition processes from cathode-trigger discharge to cathode-anode discharge were observed. It is shown that the performances of the two triggering methods investigated are quite different. Arc discharge triggered by independent electric source can be stabilized at the center of anode grid, but it is difficult to achieve such good symmetry through resistance triggering. It is also found that the triggering process is highly correlated to the behavior of emitted electrons.

Community-based psychosocial rehabilitation and prospective change in functional, clinical, and subjective experience variables in schizophrenia.

In a previous study, we found that the intensity, specificity, and longitudinality of community-based psychosocial rehabilitation services were related to superior functional outcomes for individuals diagnosed with schizophrenia. The purpose of this study was to assess the degree to which the intensity and longitudinality of services were related to improvements in subjective experience and clinical outcomes, and to examine the relationships among prospective changes in functional, clinical, and subjective experience variables. One hundred seventy-two individuals diagnosed with a schizophrenia spectrum disorder were followed for 36 months in three distinct models of community-based care. Functional, clinical, and subjective experience outcome data were gathered every 6 months over a 3-year period. Data were analyzed using hierarchical linear modeling (HLM) and P-technique factor analysis. The results indicated that (1) greater service intensity and the longitudinality of services were associated with improvement in client self-esteem; (2) there was evidence for three distinct factors of prospective rehabilitative change that corresponded to the conceptual domains of clinical, functional, and subjective experience outcomes; and (3) there was no differential program impact on symptom levels or the intrapsychic deficits. In addition, the three-factor model of outcome consisting of functional change, clinical change, and subjective experience change was similar to Strauss and Carpenter's "open-linked" system of outcome in schizophrenia. The implications of these findings for research and practice in the area of community-based rehabilitation for individuals with schizophrenia are discussed.

The impact of service characteristics on functional outcomes from community support programs for persons with schizophrenia: a growth curve analysis.

A total of 172 individuals diagnosed with a schizophrenia spectrum disorder were followed for 36 months in 3 distinct models of community-based care. Functional outcome data gathered every 6 months were combined with service implementation data to test hypotheses concerning the impact of service characteristics on prospective client outcomes. The results using hierarchical linear modeling supported associations between the intensity, specificity, and longitudinality of services and improved client outcomes. Specifically, more intense services were associated with higher levels or rates of improvement on all indices of clinical and psychosocial functioning. The specificity results suggested that services needed to be targeted to specific areas of functioning in order for improvement to occur. The effect of longitudinality was contingent on the outcome domain examined.

Eicosanoids and the esophagus.

Eicosanoids are products of arachidonic acid metabolism. Among the products produced are the prostaglandins and leukotrienes, products which are known to play important roles in health and disease of many gastrointestinal tissues. Here, we review current knowledge about eicosanoids in the esophagus, including production in healthy and diseased tissues and potential physiologic and pathophysiologic effects in two important esophageal mucosal disorders, reflux esophagitis and esophageal cancer.

A robotics-based liquid chromatographic assay for the measurement of atovaquone in plasma.

A precise and specific robotics-based liquid chromatographic (LC) method for measuring atovaquone concentrations in plasma was developed and validated, and the method was compared with an existing manual LC method. The compound was isolated from plasma by liquid-liquid extraction, separated by reversed-phase LC, and quantitated against an internal standard with UV detection. Least-squares linear regression with 1/concentration2 weighting was used as the calibration model. The range of the calibration curve for the assay under routine conditions was 0.25-50 micrograms ml-1. No endogenous interferences with the compound or the internal standard were noted in either untreated human plasma or in plasma from patients enrolled in Phase III clinical trials of atovaquone. The accuracy of the assay (determined as the percent bias) ranged from -4.8% to -9.4% in the validation runs. The intra- and interassay precisions (determined as the relative standard deviation) were less than 6.8% and 6.4%, respectively. The contribution of an internal standard on assay accuracy and precision also was examined. Interassay variability was marginally improved by the incorporation of an internal standard to the assay; accuracy and intra-assay precision were essentially unchanged. A paired t-test between estimates of atovaquone concentrations in healthy volunteer and HIV + patient human plasma samples assayed by the automated and manual methods demonstrated no significant difference (p = 0.31) between the values determined by each method.

Risks for individuals with schizophrenia who are living in the community.

OBJECTIVE: This study examined the incidence and predictors of police contact, criminal charges, and victimization among noninstitutionalized individuals with schizophrenia living in the community. METHODS: A total of 172 individuals with schizophrenia or schizoaffective disorder were recruited from community-based programs in urban Los Angeles between 1989 and 1991 and were monitored for three years. At baseline, all participants were housed and did not have co-occurring substance use disorders. Face-to-face interviews were conducted every six months. RESULTS: Eighty-three individuals (48 percent) had contact with the police during the study period. A small percentage of the contacts involved aggressive behavior against property or persons. Being younger, having had more address changes at baseline, and having a history of arrest and assault were significant predictors of police contact. Thirty-seven individuals (22 percent) reported that charges had been filed against them. Poorer social functioning, more address changes, fewer days of taking medication at baseline, and a history of arrest and assault were significant predictors of criminal charges. Sixty-five participants (38 percent of the sample) reported having been the victim of a crime during the three years, 91 percent of which was violent. Having more severe clinical symptoms and more substance use at baseline were significant predictors of victimization. CONCLUSIONS: Individuals in this sample were at least 14 times more likely to be victims of a violent crime than to be arrested for one. In general, the risk associated with being in the community was higher than the risk these individuals posed to the community

A one-year experience in the antenatal evaluation of suspected abdominal wall and bowel defects at a military tertiary referral center.

A variety of fetal abdominal wall defects and bowel anomalies are detected or suspected antenatally at institutions providing primary, secondary, and tertiary level care. Presented is a summary of a 1-year experience at a tertiary care center demonstrating a working referral network and its advantages. Of the 10 cases presented, 8 were referred and 2 originated from within our institution. The initial diagnosis was uncertain or differed from the final diagnosis in half of referred cases. Within the military, a reliable route for referral enhances prenatal evaluation and provides intensive neonatal support at delivery if needed and more immediately available surgery if indicated.

The utility of self-management procedures in modifying the classroom behaviors of mentally retarded adolescents.

Self-management procedures including the self-recording of points, the self-graphing of progress, and the self-selecting of free time activities were applied to the classroom behaviors of 12-year-old educable mentally retarded subjects. Students were first awarded points for specified appropriate behaviors. Then during the last two treatment phases, they graphed their points earnings and used these points to earn free time activities. A multiple baseline design was used in appraising the comparative effects of these three treatment conditions during spelling and reading periods. All three treatment conditions produced higher rates of appropriate behavior than did baseline conditions; however, the highest levels of appropriate behavior were achieved during the self-selected free time phases.

The comparative effectiveness of group and individually contingent free time with inner-city junior high school students.

A major purpose of the study was to assess the relative effects of group versus individually contingent free time in modifying student behaviors. Other purposes were to determine the effectiveness of well-planned lesson activities and tokens without back-up reinforcers. Eight students in an inner-city seventh-grade class of 32 blacks served as subjects. Well-organized lesson activities and success feedback via tokens did not produce high levels of desirable behavior. In contrast, group and individually contingent free time produced substantially higher levels of appropriate behavior than did the baseline conditions. The group reinforcement procedure appeared to be slightly more effective than individual reinforcement.

Neonatal hyperglycemia and diminished long-term growth in very low birth weight preterm infants.

OBJECTIVE: To investigate the association between early hyperglycemia and growth and development from hospital discharge to 2 years corrected age (CA) in very low birth weight (VLBW) infants. STUDY DESIGN: Blood glucose levels during the first 14 days after birth, weight, length and occipital-frontal circumference (OFC) at birth, hospital discharge and 4, 12 and 24 months CA, Bayley developmental scores at 12 and 24 months CA, and information on multiple clinical variables were recorded on VLBW preterm infants (N=80). The relationships between hyperglycemia, growth and developmental scores were determined using linear mixed effects regression. RESULT: Hyperglycemia was a strong predictor of poor rate of increase in weight, length and OFC until 24 months CA. Hyperglycemia was not associated with lower scores on the Bayley scales. CONCLUSION: Neonatal hyperglycemia was associated with poor physical growth until at least 2 years CA in this cohort of VLBW preterm infants.

Electrical shielding box measurement of the negative hydrogen beam from Penning ion gauge ion source.

The cold-cathode Penning ion gauge (PIG) type ion source has been used for generation of negative hydrogen (H(-)) ions as the internal ion source of a compact cyclotron. A novel method called electrical shielding box dc beam measurement is described in this paper, and the beam intensity was measured under dc extraction inside an electrical shielding box. The results of the trajectory simulation and dc H(-) beam extraction measurement were presented. The effect of gas flow rate, magnetic field strength, arc current, and extraction voltage were also discussed. In conclusion, the dc H(-) beam current of about 4 mA from the PIG ion source with the puller voltage of 40 kV and arc current of 1.31 A was extrapolated from the measurement at low extraction dc voltages.

Eicosanoids and the esophagus.

Eicosanoids are metabolites of arachidonic acid and include, among other compounds, the prostaglandins and leukotrienes. These metabolites are known to play important roles in the health and disease of many gastrointestinal tissues. Less attention, however, has been given to their functions in the esophagus. The present study, therefore, aims both to review the current knowledge about eicosanoids in healthy and diseased esophagi, and to critically assess the data pertaining to their role in the pathophysiology of gastroesophageal reflux disease.