Cognition in transmembrane domain neuregulin 1 mutant mice

Neuregulin 1 (NRG1), which has been implicated in the development of schizophrenia, is expressed widely throughout the brain and influences key neurodevelopmental processes such as myelination and neuronal migration. The heterozygous transmembrane domain Nrg1 mutant mouse (Nrg1 TM HET) exhibits a neurobehavioural phenotype relevant for schizophrenia research, characterized by the development of locomotor hyperactivity, social withdrawal, increased sensitivity to environmental manipulation, and changes to the serotonergic system. As only limited data are available on the learning and memory performance of Nrg1 TM HET mice, we conducted a comprehensive examination of these mice and their wild type-like littermates in a variety of paradigms, including fear conditioning (FC), radial arm maze (RAM), Y maze, object exploration and passive avoidance (PA). Male neuregulin 1 hypomorphic mice displayed impairments in the novel object recognition and FC tasks, including reduced interest in the novel object and reduced FC to a context, but not a discrete cue. These cognitive deficits were task-specific, as no differences were seen between mutant and control mice in spatial learning (i.e. RAM and Y maze) for both working and reference memory measures, or in the PA paradigm. These findings indicate that neuregulin 1 plays a moderate role in cognition and present further behavioural validation of this genetic mouse model for the schizophrenia candidate gene neuregulin 1.

Neuregulin 1 sustains the gene regulatory network in both trabecular and nontrabecular myocardium

RATIONALE

The cardiac gene regulatory network (GRN) is controlled by transcription factors and signaling inputs, but network logic in development and it unraveling in disease is poorly understood. In development, the membrane-tethered signaling ligand Neuregulin (Nrg)1, expressed in endocardium, is essential for ventricular morphogenesis. In adults, Nrg1 protects against heart failure and can induce cardiomyocytes to divide.

OBJECTIVE

To understand the role of Nrg1 in heart development through analysis of null and hypomorphic Nrg1 mutant mice.

METHODS AND RESULTS

Chamber domains were correctly specified in Nrg1 mutants, although chamber-restricted genes Hand1 and Cited1 failed to be activated. The chamber GRN subsequently decayed with individual genes exhibiting decay patterns unrelated to known patterning boundaries. Both trabecular and nontrabecular myocardium were affected. Network demise was spatiotemporally dynamic, the most sensitive region being the central part of the left ventricle, in which the GRN underwent complete collapse. Other regions were partially affected with graded sensitivity. In vitro, Nrg1 promoted phospho-Erk1/2-dependent transcription factor expression, cardiomyocyte maturation and cell cycle inhibition. We monitored cardiac pErk1/2 in embryos and found that expression was Nrg1-dependent and levels correlated with cardiac GRN sensitivity in mutants.

CONCLUSIONS

The chamber GRN is fundamentally labile and dependent on signaling from extracardiac sources. Nrg1-ErbB1/4-Erk1/2 signaling critically sustains elements of the GRN in trabecular and nontrabecular myocardium, challenging our understanding of Nrg1 function. Transcriptional decay patterns induced by reduced Nrg1 suggest a novel mechanism for cardiac transcriptional regulation and dysfunction in disease, potentially linking biomechanical feedback to molecular pathways for growth and differentiation.

Synthetic evaluation of the effect of health promotion: impact of a UNICEF project in 40 poor western counties of China

OBJECTIVE

To synthetically evaluate the effects of a health promotion project launched by the Ministry of Health of China and the United Nations Children's Fund (UNICEF) in 40 poor western counties of China.

STUDY DESIGN

The two surveys were cross-sectional studies. Stratified multistage random sampling was used to recruit subjects.

METHODS

Data were collected through two surveys conducted in the 40 'UNICEF project counties' in 1999 and 2000. After categorizing the 27 evaluation indicators into four aspects, a hybrid of the Analytic Hierarchy Process, the Technique for Order Preference by Similarity to Ideal Solution, and linear weighting were used to analyse the changes. The 40 counties were classified into three different levels according to differences in the synthetic indicator derived. Comparing the synthetic evaluation indicators of these two surveys, issues for implementation of the project were identified and discussed.

RESULTS

The values of the synthetic indicators were significantly higher in 2000 than in 1999 (P=0.02); this indicated that the projects were effective. Among the 40 counties, 11 counties were at a higher level in 2000, 10 counties were at a lower level, and others were in the middle level. Comparative analysis showed that 36% of village clinics were not licensed to practice medicine, nearly 50% of village clinics had no records of medicine purchases, nearly 20% of village clinics had no pressure cooker for disinfection, and 20% of pregnant women did not receive any prenatal care.

CONCLUSIONS

The health promotion projects in the 40 counties were effective. Health management, medical treatment conditions, maternal health and child health care have improved to some extent. However, much remains to be done to improve health care in these 40 poor counties. The findings of this study can help decision makers to improve the implementation of such improvements.

Schizophrenia-related endophenotypes in heterozygous neuregulin-1 'knockout' mice

Neuregulin-1 (NRG1) has been shown to play a role in glutamatergic neurotransmission and is a risk gene for schizophrenia, in which there is evidence for hypoglutamatergic function. Sensitivity to the behavioural effects of the psychotomimetic N-methyl-D-aspartate receptor antagonists MK-801 and phencyclidine (PCP) was examined in mutant mice with heterozygous deletion of NRG1. Social behaviour (sociability, social novelty preference and dyadic interaction), together with exploratory activity, was assessed following acute or subchronic administration of MK-801 (0.1 and 0.2 mg/kg) or PCP (5 mg/kg). In untreated NRG1 mutants, levels of glutamate, N-acetylaspartate and GABA were determined using high-performance liquid chromatography and regional brain volumes were assessed using magnetic resonance imaging at 7T. NRG1 mutants, particularly males, displayed decreased responsivity to the locomotor-activating effects of acute PCP. Subchronic MK-801 and PCP disrupted sociability and social novelty preference in mutants and wildtypes and reversed the increase in both exploratory activity and social dominance-related behaviours observed in vehicle-treated mutants. No phenotypic differences were demonstrated in N-acetylaspartate, glutamate or GABA levels. The total ventricular and olfactory bulb volume was decreased in mutants. These data indicate a subtle role for NRG1 in modulating several schizophrenia-relevant processes including the effects of psychotomimetic N-methyl-D-aspartate receptor antagonists.

Statistical analysis on spatial and temporal patterns of the Chinese elderly population

China contains over one-fifth of the world population. Over the past 20 years, the Chinese population has been ageing rapidly due to the dramatic family planning programs enforced by the Chinese government. These family planning programs have been implemented gradually during the last two decades and the programs implemented were varied from region to region. In this study, we statistically examined the spatial and temporal patterns of the processes of the Chinese elderly populations among the provinces, autonomous regions and municipalities (P/A/M) from 1953 to 1994. The D-statistic was used in assessing the spatial autocorrelation for the proportions of the elderly population of the 30 (29) P/A/M in the Chinese mainland. The simple T-statistic was used in measuring the temporal changes since 1953. The spatial and temporal patterns were statistically significant according to the testing statistics. We also found that the proportions of the elderly population were highly correlated with the population densities of the P/A/M. We linked these statistical results with the changes in the socio-economic situations since the founding of the People's Republic of China in 1949.

The frequency of febrile neutropenia in oncology patients receiving chemotherapy

e20691

Background:Febrile neutropenia (F/N) is a relatively common and serious side effect for oncology patients undergoing chemotherapy. Due to varying dosages and frequency of cytotoxic agents administered to oncology patients, the incidence and grade of neutropenia varies. The purpose of this study was to establish the frequency of febrile neutropenia in different chemotherapy regimens. Methods: Data was collected on 343 patients who underwent chemotherapy over a 9 month period. Regimens that caused at least one episode of febrile neutropenia in patients within that period were assessed in the study. A list of the patients on identified chemotherapy regimens during the time period was generated by the pharmacy department. Data on patients who had febrile neutropenia was obtained from their clinical notes. Clinical data was then obtained on all those patients. This information was then used to compare the frequency of febrile neutropenia in the included chemotherapy regimens. Results: 343 patients were included in this study. Of those, 41 patients developed febrile neutropenia within the 9 month period (11%); there were 49 cases of febrile neutropenia (14%) in total as some patients had more than one episode. Conclusions: Febrile neutropenia (FN) is a known potential side-effect from treatment with chemotherapy. This study highlights the rates of FN in patients treated within one centre. In patients being treated with specific chemotherapy regimens this study may guide the increased use of G-CSF and better outline the risk profile of such therapy to patients.

[Table: see text]

No significant financial relationships to disclose.

Phenotype of spontaneous orofacial dyskinesia in neuregulin-1 'knockout' mice

Studies in antipsychotic-naïve patients with schizophrenia indicate a baseline level of spontaneous involuntary movements, particularly orofacial dyskinesia. Neuregulin-1 is associated with risk for schizophrenia and its functional role can be studied in 'knockout' mice. We have shown previously that neuregulin-1 'knockouts' evidence disruption in social behaviour. Neuregulin-1 'knockouts' were assessed for four topographies of orofacial movement, both spontaneously and under challenge with the D(1)-like dopamine receptor agonist SKF 83959. Neuregulin-1 'knockouts' evidenced an increase in spontaneous incisor chattering, particularly among males. SKF 83959 induced incisor chattering, vertical jaw movements and tongue protrusions; the level of horizontal jaw movements was increased and that of tongue protrusions decreased in neuregulin-1 'knockouts'. These findings indicate that the schizophrenia risk gene neuregulin-1 is involved in the regulation of not only social behaviour but also orofacial dyskinesia. Orofacial dyskinesia in neuregulin-1 mutants may indicate some modest genetic relationship between risk for schizophrenia and vulnerability to spontaneous movement disorder.

Association studies of ALOX5 and bone mineral density in healthy adults

Animal studies suggest that arachidonate 5-lipoxygenase (encoded by ALOX5) may be a genetic determinant of bone mineral density. We tested this hypothesis in a sample of healthy men and women and did not find consistent evidence for an association between variation in this gene and either lumbar spine or femoral neck BMD.

INTRODUCTION

Phenotypic variation in bone mineral density (BMD) among healthy adults is influenced by both genetic and environmental factors. A recent mouse study implicated ALOX5, which encodes arachidonate 5-lipoxygenase, as a contributing factor to areal BMD (aBMD).

METHODS

Fifteen single nucleotide polymorphisms (SNPs) distributed throughout ALOX5 were genotyped in three healthy groups: 1,688 European American, premenopausal sisters, 512 African American premenopausal sisters and 715 European American brothers. Statistical analyses were performed in the three groups to test for association between these SNPs and femoral neck and lumbar spine aBMD.

RESULTS

Significant (p < or = 0.05) evidence of association was observed with three of the SNPs. However, despite the linkage disequilibrium between SNPs, adjacent SNPs did not provide statistical evidence of association in any of the three study groups.

CONCLUSIONS

These data do not provide consistent evidence of association between genomic variation in ALOX5 and clinical variability in aBMD in healthy subjects.

Intravitreal triamcinolone acetonide inhibits breakdown of the blood-retinal barrier through differential regulation of VEGF-A and its receptors in early diabetic rat retinas

OBJECTIVE

To elucidate the mechanism of the unique beneficial effect of intravitreal steroid therapy on diabetic macular edema, we investigated the effect of locally administered triamcinolone acetonide (TA) on the expression of vascular endothelial growth factor (VEGF)-A and its receptors in retinas of rats with streptozotocin (STZ)-induced diabetes. We then correlated the expression of these proteins with breakdown of the blood-retinal barrier (BRB).

RESEARCH DESIGN AND METHODS

Thirty-two eyes of 16 diabetic and nondiabetic rats were divided into four groups. TA was injected into the vitreous of the right eye, and saline was injected into the left eye (control) 3.5 weeks after induction of diabetes. Retinas were harvested 48 h following treatment. mRNA and protein expression of VEGF-A, VEGF-A receptor 1 (fms-like tyrosine kinase [FLT]-1), and VEGF-A receptor 2 (fetal liver kinase [FLK]-1) were determined by real-time RT-PCR and immunohistochemistry. BRB permeability was quantitated by measuring extravasated endogenous albumin and retinal thickness.

RESULTS

Diabetes-induced retinal thickness and albumin extravasation were significantly reduced in TA-treated diabetic retinas to a level similar to that in sham-treated nondiabetic eyes. A close correlation between albumin leakage and increased expression of both Vegf-a and Flk-1 was noted in the diabetic retinas. TA downregulated the expression of Vegf-a and Flk-1 but upregulated the expression of Flt-1. TA did not alter the expression of these genes in nondiabetic retinas.

CONCLUSIONS

Intravitreal injection of TA stabilizes the BRB in association with regulation of Vegf-a, Flk-1, and Flt-1 expression in retinas in the early stages of diabetes.

Disruption to social dyadic interactions but not emotional/anxiety-related behaviour in mice with heterozygous 'knockout' of the schizophrenia risk gene neuregulin-1

Clinical genetic studies have implicated neuregulin-1 [NRG1] as a leading susceptibility gene for schizophrenia. NRG1 is known to play a significant role in the developing brain, which is consistent with the prevailing neurodevelopmental model of schizophrenia. Thus, the emotional and social phenotype of adult mice with heterozygous 'knockout' of transmembrane [TM]-domain NRG1 was examined further in both sexes. Emotional/anxiety-related behaviour was assessed using the elevated plus-maze and the light-dark test. Social behaviour was examined in terms of dyadic interactions between NRG1 mutants and an unfamiliar C57BL6 conspecific in a novel environment. There was no effect of NRG1 genotype on performance in either test of emotionality/anxiety. However, previous reports of hyperactivity in NRG1 mutants were confirmed in both paradigms. In the test of social interaction, aggressive following was increased in NRG1 mutants of both sexes, together with an increase in walkovers in female mutants. These findings elaborate the specificity of the NRG1 phenotype for the social rather than the emotional/anxiety-related domain. They indicate that NRG1 is involved in the regulation of reciprocal social interaction behaviour and thus suggest a putative role for NRG1 in a schizophrenia-related endophenotype.

Store-Operated Ca 2+ Influx and Expression of TRPC Genes in Mouse Sinoatrial Node

Store-operated Ca 2+ entry was investigated in isolated mouse sinoatrial nodes (SAN) dissected from right atria and loaded with Ca 2+ indicators. Incubation of the SAN in Ca 2+ -free solution caused a substantial decrease in resting intracellular Ca 2+ concentration ([Ca 2+ ] i ) and stopped pacemaker activity. Reintroduction of Ca 2+ in the presence of cyclopiazonic acid (CPA), a sarcoplasmic reticulum Ca 2+ pump inhibitor, led to sustained elevation of [Ca 2+ ] i , a characteristic of store-operated Ca 2+ channel (SOCC) activity. Two SOCC antagonists, Gd 3+ and SKF-96365, inhibited 72±8% and 65±8% of this Ca 2+ influx, respectively. SKF-96365 also reduced the spontaneous pacemaker rate to 27±4% of control in the presence of CPA. Because members of the transient receptor potential canonical (TRPC) gene family may encode SOCCs, we used RT-PCR to examine mRNA expression of the 7 known mammalian TRPC isoforms. Transcripts for TRPC1, 2, 3, 4, 6, and 7, but not TRPC5, were detected. Immunohistochemistry using anti-TRPC1, 3, 4, and 6 antibodies revealed positive labeling in the SAN region and single pacemaker cells. These results indicate that mouse SAN exhibits store-operated Ca 2+ activity which may be attributable to TRPC expression, and suggest that SOCCs may be involved in regulating pacemaker firing rate.

Neuregulin-1/erbB-activation improves cardiac function and survival in models of ischemic, dilated, and viral cardiomyopathy

OBJECTIVES

We evaluated the therapeutic potential of a recombinant 61-residue neuregulin-1 (beta2a isoform) receptor-active peptide (rhNRG-1) in multiple animal models of heart disease.

BACKGROUND

Activation of the erbB family of receptor tyrosine kinases by rhNRG-1 could provide a treatment option for heart failure, because neuregulin-stimulated erbB2/erbB4 heterodimerization is not only critical for myocardium formation in early heart development but prevents severe dysfunction of the adult heart and premature death. Disabled erbB-signaling is also implicated in the transition from compensatory hypertrophy to failure, whereas erbB receptor-activation promotes myocardial cell growth and survival and protects against anthracycline-induced cardiomyopathy.

METHODS

rhNRG-1 was administered IV to animal models of ischemic, dilated, and viral cardiomyopathy, and cardiac function and survival were evaluated.

RESULTS

Short-term intravenous administration of rhNRG-1 to normal dogs and rats did not alter hemodynamics or cardiac contractility. In contrast, rhNRG-1 improved cardiac performance, attenuated pathological changes, and prolonged survival in rodent models of ischemic, dilated, and viral cardiomyopathy, with the survival benefits in the ischemic model being additive to those of angiotensin-converting enzyme inhibitor therapy. In addition, despite continued pacing, rhNRG-1 produced global improvements in cardiac function in a canine model of pacing-induced heart failure.

CONCLUSIONS

These beneficial effects make rhNRG-1 promising as a broad-spectrum therapeutic for the treatment of heart failure due to a variety of common cardiac diseases.

Validation of an asthma questionnaire for use in healthcare workers

BACKGROUND

Previous studies have described increased occurrence of asthma among healthcare workers, but to our knowledge there are no validated survey questionnaires with which to study this occupational group.

AIMS

To develop, validate, and refine a new survey instrument on asthma for use in epidemiological studies of healthcare workers.

METHODS

An initial draft questionnaire, designed by a multidisciplinary team, used previously validated questions where possible; the occupational exposure section was developed by updating health services specific chemical lists through hospital walk-through surveys and review of material safety data sheets. A cross-sectional validation study was conducted in 118 non-smoking subjects, who also underwent bronchial challenge testing, an interview with an industrial hygienist, and measurement of specific IgE antibodies to common aeroallergens.

RESULTS

The final version consisted of 43 main questions in four sections. Time to completion of the questionnaire ranged from 13 to 25 minutes. Test-retest reliability of asthma and allergy items ranged from 75% to 94%, and internal consistency for these items was excellent (Cronbach's alpha > or = 0.86). Against methacholine challenge, an eight item combination of asthma related symptoms had a sensitivity of 71% and specificity of 70%; against a physician diagnosis of asthma, this same combination showed a sensitivity of 79% and specificity of 98%. Agreement between self-reported exposures and industrial hygienist review was similar to previous studies and only moderate, indicating the need to incorporate more reliable methods of exposure assessment. Against the aerollergen panel, the best combinations of sensitivity and specificity were obtained for a history of allergies to dust, dust mite, and animals.

CONCLUSIONS

Initial evaluation of this new questionnaire indicates good validity and reliability, and further field testing and cross-validation in a larger healthcare worker population is in progress. The need for development of more reliable occupational exposure assessment methods that go beyond self-report is underscored.

Quantitative trait loci modifying cardiac atrial septal morphology and risk of patent foramen ovale in the mouse

Atrial septal defect (ASD) is a common congenital heart disease (CHD) occurring in 5 to 7 per 10,000 live births. Mutations in 5 human genes (NKX2.5, TBX5, GATA4, MYHC, ACTC) are known to cause dominant ASD, but these account for a minority of cases. Human and mouse data suggest that ASD exists in an anatomical continuum with milder septal variants patent foramen ovale (PFO) and atrial septal aneurysm, strongly associated with ischemic stroke and migraine. We have previously shown in inbred mice that the incidence of PFO strongly correlates with length of the interatrial septum primum, defining a quantitative trait underlying PFO risk. To better understand genetic causation of atrial septal abnormalities, we mapped quantitative trait loci (QTL) influencing septal morphology using mouse strains (QSi5 and 129T2/SvEms) maximally informative for PFO incidence and 3 quantitative septal anatomical traits including septum primum length. [QSi5x129T2/SvEms]F2 intercross animals (n=1437) were phenotyped and a whole genome scan performed at an average 17-cM interval. Statistical methodology scoring PFO as a binary phenotype was developed as a confirmatory mapping technique. We mapped 7 significant and 6 suggestive QTL modifying quantitative phenotypes, with 4 supported by binary analysis. Quantitative traits, although strongly associated with PFO (P<0.001), correlated poorly with each other and in all but 1 case QTL for different traits were nonoverlapping. Thus, multiple anatomical processes under separate genetic control contribute to risk of PFO. Our findings demonstrate the feasibility of modeling the genetic basis of common CHD using animal genetic and genomic technologies.

Polymorphisms in the bone morphogenetic protein 2 (BMP2) gene do not affect bone mineral density in white men or women

INTRODUCTION

Peak bone mineral density (BMD) achieved during adulthood is a major determinant of osteoporotic fracture in later life. Although environmental factors affect peak BMD, it is a highly heritable trait. Recently, bone morphogenetic protein 2 (BMP2) was reported as a susceptibility gene for osteoporotic fractures and low BMD in Icelandic and Danish populations.

METHODS

To determine whether polymorphisms in the BMP2 gene contribute to BMD variation in our population of healthy American whites, we tested seven single nucleotide polymorphisms (SNPs), four of which were associated with osteoporotic phenotypes in the previous study. BMD at the femoral neck and lumbar spine (L2-L4) were measured by dual energy X-ray absorptiometry (DXA) in 411 men (age 18-61) and 1,291 pre-menopausal women (age 20-50). SNP genotypes/haplotypes were tested for population-based association with BMD using analysis of variance.

RESULTS

None of the polymorphisms tested reached statistical significance (all p values >0.05) for BMD at the femoral neck or lumbar spine in either gender. Two of the SNP haplotypes spanning the entire BMP2 gene were marginally associated with BMD in men (p values=0.019-0.043). However, these haplotypes would account for only a small, if any, portion of BMD variation and would not be significant after adjustment for multiple comparisons.

CONCLUSIONS

These results demonstrate that genetic variations in BMP2 do not substantially contribute to BMD variation in our population of healthy American whites.

Murine T-box transcription factor Tbx20 acts as a repressor during heart development, and is essential for adult heart integrity, function and adaptation

The genetic hierarchies guiding lineage specification and morphogenesis of the mammalian embryonic heart are poorly understood. We now show by gene targeting that murine T-box transcription factor Tbx20 plays a central role in these pathways, and has important activities in both cardiac development and adult function. Loss of Tbx20 results in death of embryos at mid-gestation with grossly abnormal heart morphogenesis. Underlying these disturbances was a severely compromised cardiac transcriptional program, defects in the molecular pre-pattern, reduced expansion of cardiac progenitors and a block to chamber differentiation. Notably, Tbx20-null embryos showed ectopic activation of Tbx2 across the whole heart myogenic field. Tbx2 encodes a transcriptional repressor normally expressed in non-chamber myocardium, and in the atrioventricular canal it has been proposed to inhibit chamber-specific gene expression through competition with positive factor Tbx5. Our data demonstrate a repressive activity for Tbx20 and place it upstream of Tbx2 in the cardiac genetic program. Thus, hierarchical, repressive interactions between Tbx20 and other T-box genes and factors underlie the primary lineage split into chamber and non-chamber myocardium in the forming heart, an early event upon which all subsequent morphogenesis depends. Additional roles for Tbx20 in adult heart integrity and contractile function were revealed by in-vivo cardiac functional analysis of Tbx20 heterozygous mutant mice. These data suggest that mutations in human cardiac transcription factor genes, possibly including TBX20, underlie both congenital heart disease and adult cardiomyopathies.

Resistance exercise as a countermeasure to disuse-induced bone loss

During spaceflight, skeletal unloading results in loss of bone mineral density (BMD). This occurs primarily in the spine and lower body regions. This loss of skeletal mass could prove hazardous to astronauts on flights of long duration. In this study, intense resistance exercise was used to test whether a training regimen would prevent the loss of BMD that accompanies disuse. Nine subjects (5 men, 4 women) participated in a supine maximal resistance exercise training program during 17 wk of horizontal bed rest. These subjects were compared with 18 control subjects (13 men, 5 women) who followed the same bed rest protocol without exercise. Determination of treatment effect was based on measures of BMD, bone metabolism markers, and calcium balance obtained before, during, and after bed rest. Exercisers and controls had significantly (P < 0.05) different means, represented by the respective following percent changes: lumbar spine BMD, +3% vs. -1%; total hip BMD, +1% vs. -3%; calcaneus BMD, +1% vs. -9%; pelvis BMD, -0.5% vs. -3%; total body BMD, 0% vs. -1%; bone-specific alkaline phosphatase, +64% vs. 0%; alkaline phosphatase, +31% vs. +5%; osteocalcin, +43% vs. +10%; 1,25 dihydroxyvitamin D, +12% vs. -15%; parathyroid hormone intact molecule, +18% vs. -25%; and serum and ionized calcium, -1% vs. +1%. The difference in net calcium balance was also significant (+21 mg/day vs. -199 mg/day, exercise vs. control). The gastrocnemius and soleus muscle volumes decreased significantly in the exercise group, but the loss was significantly less than observed in the control group. The results indicate that resistance exercise had a positive treatment effect and thus might be useful as a countermeasure to prevent the deleterious skeletal changes associated with long-duration spaceflight.

Transcriptional regulation of the murine Connexin40 promoter by cardiac factors Nkx2-5, GATA4 and Tbx5

OBJECTIVE

Connexin40 (Cx40) is a gap junction protein expressed specifically in developing and mature atrial myocytes and cells of the conduction system. In this report, we identify cis-acting elements within the mouse Cx40 promoter and unravel part of the complex pathways involved in the cardiac expression of this gene.

METHODS

To identify the factors involved in the cardiac expression of Cx40, we used transient transfections in mammalian cells coupled with electrophoretic mobility shift assays (EMSA) and RT-PCR.

RESULTS

Within the promoter region, we identified the minimal elements required for transcriptional activity within 150 base pairs (bp) upstream of the transcriptional start site. Several putative regulatory sites for transcription factors were predicted within this region by computer analysis, and we demonstrated that the nuclear factors Sp1, Nkx2-5, GATA4 and Tbx5 could interact specifically with elements present in the minimal promoter region of the Cx40. Furthermore, co-transfection experiments showed the ability of Nkx2-5 and GATA4 to transactivate the minimal Cx40 promoter while Tbx5 repressed Nkx2-5/GATA4-mediated activation. Mutagenesis of the Nkx2-5 core site in the Cx40 promoter led to significantly decreased activity in rat smooth muscle cell line A7r5. Consistent with this, mouse embryos lacking Nkx2-5 showed a marked decrease in Cx40 expression.

CONCLUSION

In this work, we cloned the promoter region of the Cx40 and demonstrated that the core promoter was modulated by cardiac transcriptional factors Nkx2-5, Tbx5 and GATA4 acting together with ubiquitous Sp1.

Hearing impairment in essential tremor

OBJECTIVE

To assess hearing in patients with essential tremor (ET) vs patients with Parkinson disease (PD) and normal controls.

METHODS

The authors assessed demographic and clinical information including use of hearing aids in 250 patients with ET, 127 patients with PD, and 127 normal controls. The authors administered the Nursing Home Hearing Handicap Index (NHHI), a validated measure of hearing disability. Regression techniques were used to adjust for factors such as age and sex. The authors assessed a complete audiologic evaluation in a subset of patients with ET.

RESULTS

Patients with ET had worse adjusted NHHI scores when compared to patients with PD (p < 0.001), controls (p < 0.001), and both (p < 0.001). A higher percentage of patients with ET also used hearing aids (p < 0.0001). In the ET group, hearing loss was associated with tremor severity (p = 0.02) and tended to be associated with older age (p = 0.06), male sex (p = 0.06), and the absence of dystonia (p = 0.18). Audiology testing was consistent with high-frequency sensorineural hearing loss. Central processing was not disproportionally greater than peripheral loss.

CONCLUSION

Patients with ET have increased hearing disability compared to patients with PD and normal controls, which correlates with tremor severity.

Health care service use by Chinese seniors in British Columbia, Canada

This paper assesses whether the same factors are predictive of health service utilization among this ethnic group as is true of the general population of seniors. The data suggest that the health of Chinese elders is just as bad as other seniors, and their utilization is very similar. They have a strong preference for Western over Chinese medicine and for Western trained doctors over Chinese practitioners, and use services with Chinese staff, probably because of language. Similarly, the predictors of service use are strikingly similar to predictors revealed in utilization studies throughout the industrialized world. Ability to speak English, immigration history, and country of origin are unrelated to the use of these services. However, approximately half of Chinese seniors also engage in traditional Chinese care. Religious beliefs and a preference for traditional Chinese medicine are strongly predictive of the use of traditional care. It would appear that distinctive culture is related to the use of traditional care, but not the use of the western health care system.