Picrotoxin accelerates relaxation of GABAC receptors

Picrotoxin is a plant alkaloid that is often used to block the activity of neuronal GABA and glycine receptors. However, the mechanism by which picrotoxin inhibits these receptors is still in debate. In this study, we investigated the picrotoxin inhibition on perch-rho subunits expressed heterologously in Xenopus laevis oocytes, and on native GABA(C) receptors of perch bipolar cells. Both competitive and noncompetitive mechanisms were observed for picrotoxin inhibition of the GABA(C) receptor. In oocytes expressing the rho1A subunit, terminating simultaneously the coapplication of GABA and picrotoxin induced a large rebound of membrane current. In addition, picrotoxin significantly accelerated the kinetics of GABA responses, particularly in the relaxation (offset) phase of GABA currents. Both current rebound and the large acceleration of GABA relaxation were unique to picrotoxin inhibition and were not observed with the competitive antagonist (1,2,5,6-tetrahydropyridin-4-yl)-methylphosphinic acid or the allosteric modulator zinc. The change in kinetics induced by picrotoxin was also observed on receptors formed by other GABA rho subunits, as well as on the GABA(C) receptors of retinal bipolar cells. Based on these observations, we proposed a model in which picrotoxin binds to the GABA(C) receptor in both channel open and closed states. Overall, this model provides a remarkably good approximation of the experimental findings we observed for picrotoxin inhibition of GABA(C) receptors. These results support an allosteric mechanism of picrotoxin inhibition of ligand-gated chloride channels.     

马兜铃酸的倍半萜的酯类化合物VI.绵毛马兜铃中马兜铃酸萜酯I的结构鉴定

从绵毛马兜铃(Aristolocha mannisima Hance)中分得一个马兜铃酸倍半萜的酯类化合物,经红外、紫外、高分辩质谱和多种一维和二维核磁共振谱鉴定,确定了其骨架结构及顺反构型,命名为马兜铃酸萜酯I。     

Peer Reviewed: Strategies for Achieving Healthy Energy Balance Among African Americans in the Mississippi Delta

Introduction

Low-income African Americans who live in rural areas of the Deep South are particularly vulnerable to diseases associated with unhealthy energy imbalance. The Centers for Disease Control and Prevention (CDC) has suggested various physical activity strategies to achieve healthy energy balance. Our objective was to conduct formal, open-ended discussions with low-income African Americans in the Mississippi Delta to determine 1) their dietary habits and physical activity levels, 2) their attitudes toward CDC''s suggested physical activity strategies, and 3) their suggestions on how to achieve CDC''s strategies within their own environment.

Methods

A qualitative method (focus groups) was used to conduct the study during 2005. Prestudy meetings were held with African American lay health workers to formulate a focus group topic guide, establish inclusion criteria for focus group participants, select meeting sites and times, and determine group segmentation guidelines. Focus groups were divided into two phases.

Results

All discussions and focus group meetings were held in community centers within African American neighborhoods in the Mississippi Delta and were led by trained African American moderators. Phase I focus groups identified the following themes: overeating, low self-esteem, low income, lack of physical exercise, unhealthy methods of food preparation, a poor working definition of healthy energy balance, and superficial knowledge of strategies for achieving healthy energy balance. Phase 2 focus groups identified a preference for social support-based strategies for increasing physical activity levels.

Conclusion

Energy balance strategies targeting low-income, rural African Americans in the Deep South may be more effective if they emphasize social interaction at the community and family levels and incorporate the concept of community volunteerism.     

Clinical multimorbidity and physical function in older adults: a record and health status linkage study in general practice

BACKGROUND: Multiple chronic conditions occurring in the same individual are associated with adverse health outcomes. In family practice, individuals are seen who, over time, may experience many different symptoms, illnesses and chronic diseases. Measures for defining multimorbidity, which incorporate the diverse range of health problems seen in population-based family practice, remain to be developed. We have investigated whether routinely collected consultation data could be used as the basis for a simple classification of multimorbidity that reflects an individual's overall health status. METHODS: Morbidity consultation data for 9,439 English patients aged 50 years and over in an 18-month time period were linked to their self-reported physical health status measured by Short-Form 12 at the end point. Associations between physical function and all-cause multimorbidity counts were estimated relative to single morbidity only, and between physical function and morbidity severity (185 morbidities categorized on four ordinal scales of severity) relative to persons who had not consulted about any of the 185. RESULTS: In the 18-month period, 19% had consulted for a single morbidity and 23% for six or more (a high multimorbidity count). An estimated 24% of poor physical function in the family practice consulting population may be attributable to high multimorbidity. There was an increasing strength of association between poor physical function and increasing severity of multimorbidity on all four severity scales. Estimated associations (adjusted odds ratios) of the most severe morbidity categories with poor physical function were, for each of the four scales, respectively, 5.6 for chronicity [95% confidence interval (CI) 4.4-7.1], 7.0 for time course (4.5-10.6) and 3.6 for health care use (2.0-6.6) and for patient impact (6.7; 5.2-8.8). CONCLUSIONS: Multimorbidity defined by using routinely collected family practice consultation data and classified by count and by severity was associated with poorer physical function. This approach offers the potential for systematic use of routine records to classify multimorbidity and to identify groups with high likelihood of poor physical status for needs assessment and targeted intervention.     

Vaccination with coxsackievirus B3 virus-like particles elicits humoral immune response and protects mice against myocarditis

Coxsackievirus B3 (CVB3), along with other enteroviruses, is involved in about 50% of myocarditis cases and in the pathogenesis of dilated cardiomyopathy. Prevention of CVB3 infection is therefore highly desirable. Virus-like particles (VLPs) are structurally similar to native virus particles and therefore are far better immunogens than any other subunit vaccines. Recombinant baculoviruses carrying either the intact, entire coding region of CVB3 or the four individual coding regions for virus proteins 1-4 (VP1-4) were constructed. Expression of CVB3 capsid proteins in insect cells infected with recombinant baculovirus was detected by immunofluorescence and Western blot analysis. Sucrose gradient ultracentrifugation fractions of the infected cell lysates contained peaks of CVB3 antigen with an approximate density of 1.14g/ml. Electron microscopy demonstrated the presence of VLP in these sucrose fractions. The CVB3 VLP was non-infectious in tissue culture. SWR (H-2(q)) mice vaccinated with CVB3 VLP developed antibodies to CVB3 capsid proteins after the first boost. Antibody titre was comparable to the level induced by an attenuated CVB3 vaccine. Vaccinated animals were protected from myocarditis when subsequently challenged with cardiovirulent CVB3 (chimera-2). Vaccination with VLP produced from the complete CVB3 coding region gave a greater immune response and afforded better protection than with VLP from the quadruple expression vector. These results demonstrate that CVB3 capsid proteins expressed in insect cells have the intrinsic capacity to assemble into non-infectious VLP, which afforded protection from CVB3 infection to mice when used as a vaccine.     

Preclinical to Clinical Translation of CNS Transporter Occupancy of TD-9855, a Novel Norepinephrine and Serotonin Reuptake Inhibitor

Background:

Monoamine reuptake inhibitors exhibit unique clinical profiles that reflect distinct engagement of the central nervous system (CNS) transporters.

Methods:

We used a translational strategy, including rodent pharmacokinetic/pharmacodynamic modeling and positron emission tomography (PET) imaging in humans, to establish the transporter profile of TD-9855, a novel norepinephrine and serotonin reuptake inhibitor.

Results:

TD-9855 was a potent inhibitor of norepinephrine (NE) and serotonin 5-HT uptake in vitro with an inhibitory selectivity of 4- to 10-fold for NE at human and rat transporters. TD-9855 engaged norepinephrine transporters (NET) and serotonin transporters (SERT) in rat spinal cord, with a plasma EC₅₀ of 11.7ng/mL and 50.8ng/mL, respectively, consistent with modest selectivity for NET in vivo.Accounting for species differences in protein binding, the projected human NET and SERT plasma EC₅₀ values were 5.5ng/mL and 23.9ng/mL, respectively. A single-dose, open-label PET study (4–20mg TD-9855, oral) was conducted in eight healthy males using the radiotracers [¹¹C]-3-amino-4- [2-[(di(methyl)amino)methyl]phenyl]sulfanylbenzonitrile for SERT and [¹¹C]-(S,S)-methylreboxetine for NET. The long pharmacokinetic half-life (30–40h) of TD-9855 allowed for sequential assessment of SERT and NET occupancy in the same subject. The plasma EC₅₀ for NET was estimated to be 1.21ng/mL, and at doses of greater than 4mg the projected steady-state NET occupancy is high (>75%). After a single oral dose of 20mg, SERT occupancy was 25 (±8)% at a plasma level of 6.35ng/mL.

Conclusions:

These data establish the CNS penetration and transporter profile of TD-9855 and inform the selection of potential doses for future clinical evaluation.     

Statement: occupational therapy provision for children with learning disabilities and/or mild to moderate perceptual and motor deficits.

This paper discusses three major issues in the provision of occupational therapy services to persons with learning disabilities and/or mild to moderate perceptual and motor deficits. The issues are (a) the historical influence of federal legislation on the scope and content of occupational therapy services to persons with these disabilities; (b) the provision of occupational therapy services for this population from infancy to adulthood; and (c) the context of service provision and efficacy of occupational therapy models.     

Analysis of JHM central nervous system infections in rats

Intracerebral inoculation of murine coronavirus JHM into 2- to 3-day-old Wistar Furth rats causes an acute encephalomyelitis, while inoculations at 10 days of age usually result in hind leg paralysis. To examine the distribution of viral antigens within this infected central nervous system (CNS) tissue, we used the avidin-biotin-peroxidase method to detect monoclonal and polyclonal antibodies bound to JHM structural proteins; in addition we used the Western blot technique to detect viral proteins. Our study demonstrated the following characteristics: Infected neuronal and glial cells produced viral nucleocapsid and E2 glycoprotein. The synthesis of these viral structural proteins was not restricted to cells in any particular part of the central nervous system. While JHM E2 proteins could be detected in individual cells of JHM-infected CNS tissue, the relative level of detectable E2 protein in the total CNS tissue of infected rats was reduced by more than 13-fold compared with JHM-infected tissue culture cells. Hippocampus neuronal cells provided a sensitive indication of JHM infection. These cells invariably contained antigens in both acutely and chronically infected animals. The distribution of cells containing viral antigens differed markedly for JHM-induced acute encephalitis and chronic demyelinating disease. Acutely infected brains had large lesions containing low levels of viral antigen scattered throughout the brain. One percent to ten percent of histologically normal cells in many parts of the brain contained viral antigens; in addition, more neuronal cells than glial cells were observed to be antigen-positive. The hippocampus appeared normal with hematoxylin-eosin staining; however, a scattered infection of neuronal cells was apparent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Implementation of enhanced dynamic wedges in pinnacle treatment planning system

Enhanced dynamic wedges (EDW) provide many advantages over traditional hard wedges for linear accelerator treatments. Along with these advantages comes the responsibility of ensuring that this complex technology delivers the correct dose to patients. This involves determining the enhanced dynamic wedge factors for various field sizes and depths for use in the hand calculation of monitor units (MUs). The accurate representation of dynamic wedges in the treatment planning computer must also be ensured. This is required so that the final isodose distributions are correct and the MUs calculated by the treatment planning computer match those determined by hand calculation. We have commissioned and implemented the use of EDW in the Pinnacle radiation therapy planning system. The modeled dose profiles agree with the measured ones with a maximum difference of 2%. The MUs generated by Pinnacle are also within 2% of those calculated independently. The process of data collection and verification, beam modeling, and a discussion of a potential pitfall encountered in this process are presented in this paper.