[Relevance of health geographic research for dermatology]

The association between geographic and medical aspects is a well-known phenomenon, which also occurs in dermatological research. This article reviews the field of health geography, the history of the association between spatial location and health, and focuses on current areas of research. Research focusing on explaining regional variations in health refer to individual aspects and needs, population factors, environmental factors, and health care delivery structures in specific regions, as well as the interaction between them. Regional healthcare research is primarily concerned with access to health services and on the utilisation of those services. Methodologically, the analysis of geodata and the application of geographic information systems (GIS) and spatial modelling play a major role in this field. Dermatological research and dermatological practice can benefit from the findings of the regional analysis of access, utilisation, and variations in order to obtain a more detailed picture of care and thus to optimise care.

LIGHT/LTβR signaling regulates self-renewal and differentiation of hematopoietic and leukemia stem cells

The production of blood cells during steady-state and increased demand depends on the regulation of hematopoietic stem cell (HSC) self-renewal and differentiation. Similarly, the balance between self-renewal and differentiation of leukemia stem cells (LSCs) is crucial in the pathogenesis of leukemia. Here, we document that the TNF receptor superfamily member lymphotoxin-β receptor (LTβR) and its ligand LIGHT regulate quiescence and self-renewal of murine and human HSCs and LSCs. Cell-autonomous LIGHT/LTβR signaling on HSCs reduces cell cycling, promotes symmetric cell division and prevents primitive HSCs from exhaustion in serial re-transplantation experiments and genotoxic stress. LTβR deficiency reduces the numbers of LSCs and prolongs survival in a murine chronic myeloid leukemia (CML) model. Similarly, LIGHT/LTβR signaling in human G-CSF mobilized HSCs and human LSCs results in increased colony forming capacity in vitro. Thus, our results define LIGHT/LTβR signaling as an important pathway in the regulation of the self-renewal of HSCs and LSCs.

Analysis of soluble or titanium dioxide derived titanium levels in human whole blood: consensus from an inter-laboratory comparison

Exposure to titanium (Ti),viathe ingestion of pigment grade Ti dioxide (TiO₂), is commonplace for westernised populations.

[Morbidity differences according to nursing stage and nursing setting in long-term care patients: Results of a claims data based study]

BACKGROUND

We analyzed the differences in morbidity patterns of chronic diseases between long-term care dependent persons in nursing homes compared to those dwelling in the community. We also investigated morbidity differences between long-term care need stages in Germany.

MATERIALS AND METHODS

The study included claims data of one nationwide operating statutory health insurance in 2006. Inclusion criteria were age ≥ 65 years, minimum 1 out of 46 diagnoses in at least 3 quarters of the year (n = 8,670). A comparison population was formed with n = 114,962. Prevalences, relative risks, and odds ratios for the risk of nursing home care were calculated.

RESULTS

In the bivariate analysis, only three chronic diseases - dementia, urinary incontinence, and chronic heart failure - showed a higher risk for nursing home care. Regression analysis revealed that only dementia showed higher odds related to the stage of nursing needs.

CONCLUSION

Among the chronic diseases, only dementia shows a substantially elevated risk for nursing home care. Risk studies on other chronic diseases associated with higher risks of long-term care dependency and specific intervention strategies aiming at delaying or preventing nursing home admission should be developed.

Dementia in the USA: state variation in prevalence

BACKGROUND

The number of dementia patients will increase over the next decades. However, we lack information on the geographic distribution of these patients. We aimed to describe the variation of dementia prevalence and to then compare the observed to expected prevalence.

METHODS

This study is based on a 20% sample of Medicare beneficiaries in 2008. The crude dementia prevalence was calculated and age/sex standardized to the US population for states. We used the World Alzheimer Report 2009 prevalence to compare estimates.

RESULTS

4.8 million persons were included. The adjusted prevalence is 8.24%, varying from 5.96 to 9.55% across states. The diagnosed prevalence is lower than the expected in most states. Overall, we estimate over 100 000 undiagnosed dementia patients in Medicare.

CONCLUSIONS

The high state variation suggests that the number of diagnosed dementia cases does not fall evenly across all states and hence may require different levels of state-level planning.

[Quality in Revision Arthroplasty: A Comparison between Claims Data Analysis and External Quality Assurance]

BACKGROUND

External quality assurance for revisions of total knee arthroplasty (TKA) and total hip arthroplasty (THA) are carried out through the AQUA institute in Germany. Data are collected by the providers and are analyzed based on predefined quality indicators from the hospital stay in which the revision was performed. The present study explores the possibility to add routine data analysis to the existing external quality assurance (EQS). Differences between methods are displayed. The study aims to quantify the benefit of an additional analysis that allows patients to be followed up beyond the hospitalization itself.

MATERIAL AND METHODS

All persons insured in an AOK sickness fund formed the population for analysis. Revisions were identified using the same algorithm as the existing external quality assurance. Adverse events were defined according to the AQUA indicators for the years 2008 to 2011.The hospital stay in which the revision took place and a follow-up of 30 days were included. For re-operation and dislocation we also defined a 365 days interval for additional follow-up. The results were compared to the external quality control reports.

RESULTS

Almost all indicators showed higher events in claims data analysis than in external quality control. Major differences are seen for dislocation (EQS SD: 1.87 vs. claims data [cd] SD: 2.06 %, cd+30 d: 2.91 %, cd+365 d: 7.27 %) and reoperation (hip revision: EQS SD: 5.88 % vs. claims data SD: 8.79 % cd+30 d: 9.82 %, cd+365 d: 15.0 %/knee revision: EQS SD: 3.21 % vs. claims data SD: 4.07 %, cd+30 d: 4.6 %, cd+365 d: 15.43 %). Claims data could show additional adverse events for all indicators after the initial hospital stay, rising to 77 % of all events.

CONCLUSIONS

The number of adverse events differs between the existing external quality control and our claims data analysis. Claims data give the opportunity to complement existing methods of quality control though a longer follow-up, when many complications become evident.

Type I interferon signaling genes in recurrent major depression: increased expression detected by whole-blood RNA sequencing

A study of genome-wide gene expression in major depressive disorder (MDD) was undertaken in a large population-based sample to determine whether altered expression levels of genes and pathways could provide insights into biological mechanisms that are relevant to this disorder. Gene expression studies have the potential to detect changes that may be because of differences in common or rare genomic sequence variation, environmental factors or their interaction. We recruited a European ancestry sample of 463 individuals with recurrent MDD and 459 controls, obtained self-report and semi-structured interview data about psychiatric and medical history and other environmental variables, sequenced RNA from whole blood and genotyped a genome-wide panel of common single-nucleotide polymorphisms. We used analytical methods to identify MDD-related genes and pathways using all of these sources of information. In analyses of association between MDD and expression levels of 13 857 single autosomal genes, accounting for multiple technical, physiological and environmental covariates, a significant excess of low P-values was observed, but there was no significant single-gene association after genome-wide correction. Pathway-based analyses of expression data detected significant association of MDD with increased expression of genes in the interferon α/β signaling pathway. This finding could not be explained by potentially confounding diseases and medications (including antidepressants) or by computationally estimated proportions of white blood cell types. Although cause-effect relationships cannot be determined from these data, the results support the hypothesis that altered immune signaling has a role in the pathogenesis, manifestation, and/or the persistence and progression of MDD.

Genetic variant predicts bevacizumab-induced hypertension in ECOG-5103 and ECOG-2100

BACKGROUND

Bevacizumab has broad anti-tumour activity, but substantial risk of hypertension. No reliable markers are available for predicting bevacizumab-induced hypertension.

METHODS

A genome-wide association study (GWAS) was performed in the phase III bevacizumab-based adjuvant breast cancer trial, ECOG-5103, to evaluate for an association between genotypes and hypertension. GWAS was conducted in those who had experienced systolic blood pressure (SBP) >160 mm Hg during therapy using binary analysis and a cumulative dose model for the total exposure of bevacizumab. Common toxicity criteria (CTC) grade 3-5 hypertension was also assessed. Candidate SNP validation was performed in the randomised phase III trial, ECOG-2100.

RESULTS

When using the phenotype of SBP>160 mm Hg, the most significant association in SV2C (rs6453204) approached and met genome-wide significance in the binary model (P=6.0 × 10(-8); OR=3.3) and in the cumulative dose model (P=4.7 × 10(-8); HR=2.2), respectively. Similar associations with rs6453204 were seen for CTC grade 3-5 hypertension but did not meet genome-wide significance. Validation study from ECOG-2100 demonstrated a statistically significant association between this SNP and grade 3/4 hypertension using the binary model (P-value=0.037; OR=2.4).

CONCLUSIONS

A genetic variant in SV2C predicted clinically relevant bevacizumab-induced hypertension in two independent, randomised phase III trials.

Convergent functional genomics of schizophrenia: from comprehensive understanding to genetic risk prediction

We have used a translational convergent functional genomics (CFG) approach to identify and prioritize genes involved in schizophrenia, by gene-level integration of genome-wide association study data with other genetic and gene expression studies in humans and animal models. Using this polyevidence scoring and pathway analyses, we identify top genes (DISC1, TCF4, MBP, MOBP, NCAM1, NRCAM, NDUFV2, RAB18, as well as ADCYAP1, BDNF, CNR1, COMT, DRD2, DTNBP1, GAD1, GRIA1, GRIN2B, HTR2A, NRG1, RELN, SNAP-25, TNIK), brain development, myelination, cell adhesion, glutamate receptor signaling, G-protein-coupled receptor signaling and cAMP-mediated signaling as key to pathophysiology and as targets for therapeutic intervention. Overall, the data are consistent with a model of disrupted connectivity in schizophrenia, resulting from the effects of neurodevelopmental environmental stress on a background of genetic vulnerability. In addition, we show how the top candidate genes identified by CFG can be used to generate a genetic risk prediction score (GRPS) to aid schizophrenia diagnostics, with predictive ability in independent cohorts. The GRPS also differentiates classic age of onset schizophrenia from early onset and late-onset disease. We also show, in three independent cohorts, two European American and one African American, increasing overlap, reproducibility and consistency of findings from single-nucleotide polymorphisms to genes, then genes prioritized by CFG, and ultimately at the level of biological pathways and mechanisms. Finally, we compared our top candidate genes for schizophrenia from this analysis with top candidate genes for bipolar disorder and anxiety disorders from previous CFG analyses conducted by us, as well as findings from the fields of autism and Alzheimer. Overall, our work maps the genomic and biological landscape for schizophrenia, providing leads towards a better understanding of illness, diagnostics and therapeutics. It also reveals the significant genetic overlap with other major psychiatric disorder domains, suggesting the need for improved nosology.

Variation in antibiotic prescriptions: is area deprivation an explanation? Analysis of 1.2 million children in Germany

PURPOSE

Inadequate use of antibiotics can lead to problems such as resistance. Overuse is especially a problem for children, since they are more affected by acute (often virus-caused) infections. While the problem has been addressed internationally over the past several years, regional variations in prescriptions are striking. Therefore, the present study aims to analyze regional variations in antibiotic prescription on a district level in Germany and tries to identify reasons for those variations through adding possible influencing factors to the analysis on individual and district levels.

METHODS

We analyzed 1.2 million children insured in a German health insurance fund. Antibiotic prescriptions were quantified in 2010 and reasons for prescriptions were analyzed in multilevel regressions based on the district of residence, regional deprivation, and age and sex of the child.

RESULTS

Thirty-six percent of all children aged 0-17 years received an antibiotic prescription in 2010. In the south, prevalences are generally lower, and also to the very north. The highest prevalences are found in the close-to-border districts in the west, as well as in a band throughout the middle of Germany, in rather low population density areas. Regional variation in the prevalence range from 19 to 53 % between districts. Regional deprivation can explain part of this variation.

CONCLUSIONS

Including area deprivation measures helped identify an influence of especially regional income and occupational deprivation on antibiotic prescriptions for children. Regional analysis such as this can help identify specific regions and groups of persons to address information programs on the risks of preventable antibiotic consumption and alternative treatment methods.

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.

Five-year follow-up on the PAT study: specific immunotherapy and long-term prevention of asthma in children

BACKGROUND

A 3-year course of specific immunotherapy (SIT) in children with hay fever to grass and/or birch pollen significantly reduced the risk of developing asthma. To investigate the long-term preventive effect, we performed a follow up--2 years after termination of immunotherapy.

METHODS

A total of 183 children, aged 6-14 years with grass and/or birch pollen allergy could be investigated 2 years after discontinuation of SIT or no treatment. Conjunctival provocation tests (CPTs) and methacholine bronchial provocation tests were carried out during the season and winter after 5 years. The development of asthma was assessed by clinical evaluation.

RESULTS

The significant improvement in hay fever and CPT results observed after 3 years of SIT persisted at the 5-year follow-up. No difference in bronchial responsiveness to methacholine was found after 5 years because of spontaneous improvement during the follow-up period in the control patients. The immunotherapy-treated children had significantly less asthma after 5 years as evaluated by clinical symptoms [odds ratio 2.68 (1.3-5.7)] in favor of SIT for prevention of development of asthma and significantly less patients reported an increase in asthma scores (P < 0.01).

CONCLUSION

Immunotherapy for 3 years with standardized allergen extracts of grass and/or birch shows long-term clinical effect and preventive effect on development of asthma in children with seasonal rhinoconjunctivitis.

A Continuation Method for Nash Equilibria in Structured Games

Structured game representations have recently attracted interest as models for multi-agent artificial intelligence scenarios, with rational behavior most commonly characterized by Nash equilibria. This paper presents efficient, exact algorithms for computing Nash equilibria in structured game representations, including both graphical games and multi-agent influence diagrams (MAIDs). The algorithms are derived from a continuation method for normal-form and extensive-form games due to Govindan and Wilson; they follow a trajectory through a space of perturbed games and their equilibria, exploiting game structure through fast computation of the Jacobian of the payoff function. They are theoretically guaranteed to find at least one equilibrium of the game, and may find more. Our approach provides the first efficient algorithm for computing exact equilibria in graphical games with arbitrary topology, and the first algorithm to exploit fine-grained structural properties of MAIDs. Experimental results are presented demonstrating the effectiveness of the algorithms and comparing them to predecessors. The running time of the graphical game algorithm is similar to, and often better than, the running time of previous approximate algorithms. The algorithm for MAIDs can effectively solve games that are much larger than those solvable by previous methods.

Genome-wide discovery of transcriptional modules from DNA sequence and gene expression

In this paper, we describe an approach for understanding transcriptional regulation from both gene expression and promoter sequence data. We aim to identify transcriptional modules--sets of genes that are co-regulated in a set of experiments, through a common motif profile. Using the EM algorithm, our approach refines both the module assignment and the motif profile so as to best explain the expression data as a function of transcriptional motifs. It also dynamically adds and deletes motifs, as required to provide a genome-wide explanation of the expression data. We evaluate the method on two Saccharomyces cerevisiae gene expression data sets, showing that our approach is better than a standard one at recovering known motifs and at generating biologically coherent modules. We also combine our results with binding localization data to obtain regulatory relationships with known transcription factors, and show that many of the inferred relationships have support in the literature.

Discovering molecular pathways from protein interaction and gene expression data

In this paper, we describe an approach for identifying 'pathways' from gene expression and protein interaction data. Our approach is based on the assumption that many pathways exhibit two properties: their genes exhibit a similar gene expression profile, and the protein products of the genes often interact. Our approach is based on a unified probabilistic model, which is learned from the data using the EM algorithm. We present results on two Saccharomyces cerevisiae gene expression data sets, combined with a binary protein interaction data set. Our results show that our approach is much more successful than other approaches at discovering both coherent functional groups and entire protein complexes.

Representation Dependence in Probabilistic Inference

Non-deductive reasoning systems are often representation dependent: representing the same situation in two different ways may cause such a system to return two different answers. Some have viewed this as a significant problem. For example, the principle of maximum entropyhas been subjected to much criticism due to its representation dependence. There has, however, been almost no work investigating representation dependence. In this paper, we formalize this notion and show that it is not a problem specific to maximum entropy. In fact, we show that any representation-independent probabilistic inference procedure that ignores irrelevant information is essentially entailment, in a precise sense. Moreover, we show that representation independence is incompatible with even a weak default assumption of independence. We then show that invariance under a restricted class of representation changes can form a reasonable compromise between representation independence and other desiderata, and provide a construction of a family of inference procedures that provides such restricted representation independence, using relative entropy.

Efficient Solution Algorithms for Factored MDPs

This paper addresses the problem of planning under uncertainty in large Markov Decision Processes (MDPs). Factored MDPs represent a complex state space using state variables and the transition model using a dynamic Bayesian network. This representation often allows an exponential reduction in the representation size of structured MDPs, but the complexity of exact solution algorithms for such MDPs can grow exponentially in the representation size. In this paper, we present two approximate solution algorithms that exploit structure in factored MDPs. Both use an approximate value function represented as a linear combination of basis functions, where each basis function involves only a small subset of the domain variables. A key contribution of this paper is that it shows how the basic operations of both algorithms can be performed efficiently in closed form, by exploiting both additive and context-specific structure in a factored MDP. A central element of our algorithms is a novel linear program decomposition technique, analogous to variable elimination in Bayesian networks, which reduces an exponentially large LP to a provably equivalent, polynomial-sized one. One algorithm uses approximate linear programming, and the second approximate dynamic programming. Our dynamic programming algorithm is novel in that it uses an approximation based on max-norm, a technique that more directly minimizes the terms that appear in error bounds for approximate MDP algorithms. We provide experimental results on problems with over 10^40 states, demonstrating a promising indication of the scalability of our approach, and compare our algorithm to an existing state-of-the-art approach, showing, in some problems, exponential gains in computation time.

Decomposing gene expression into cellular processes

We propose a probabilistic model for cellular processes, and an algorithm for discovering them from gene expression data. A process is associated with a set of genes that participate in it; unlike clustering techniques, our model allows genes to participate in multiple processes. Each process may be active to a different degree in each experiment. The expression measurement for gene g in array a is a sum, over all processes in which g participates, of the activity levels of these processes in array a. We describe an iterative procedure, based on the EM algorithm, for decomposing the expression matrix into a given number of processes. We present results on Yeast gene expression data, which indicate that our approach identifies real biological processes.

Rich probabilistic models for gene expression

Clustering is commonly used for analyzing gene expression data. Despite their successes, clustering methods suffer from a number of limitations. First, these methods reveal similarities that exist over all of the measurements, while obscuring relationships that exist over only a subset of the data. Second, clustering methods cannot readily incorporate additional types of information, such as clinical data or known attributes of genes. To circumvent these shortcomings, we propose the use of a single coherent probabilistic model, that encompasses much of the rich structure in the genomic expression data, while incorporating additional information such as experiment type, putative binding sites, or functional information. We show how this model can be learned from the data, allowing us to discover patterns in the data and dependencies between the gene expression patterns and additional attributes. The learned model reveals context-specific relationships, that exist only over a subset of the experiments in the dataset. We demonstrate the power of our approach on synthetic data and on two real-world gene expression data sets for yeast. For example, we demonstrate a novel functionality that falls naturally out of our framework: predicting the "cluster" of the array resulting from a gene mutation based only on the gene's expression pattern in the context of other mutations.

A high-throughput alphavirus-based expression cloning system for mammalian cells

We have developed a widely applicable functional genomics strategy based on alphavirus expression vectors. The technology allows for rapid identification of genes encoding a functional activity such as binding of a defined ligand. Complementary DNA (cDNA) libraries were expressed in mammalian cells following infection with recombinant Sindbis virus (SIN replicon particles), a member of the Alphavirus genus. Virus-infected cells that specifically bound a ligand of choice were isolated using fluorescence-activated cell sorting (FACS). Replication-competent, infective SIN replicon particles harboring the corresponding cDNA were amplified in a next step. Within one round of selection, viral clones encoding proteins recognized by monoclonal antibodies or Fc-fusion molecules could be isolated and sequenced. Moreover, using the same viral libraries, a plaque-lift assay was established that allowed the identification of secreted, intracellular, and membrane proteins.

Eosinophil cationic protein and eosinophil protein X in the nasal lavage of children during the first 4 weeks of life. SPACE Collaborative Study Team

Eosinophil cationic protein (ECP) and eosinophil protein X (EPX) are well established as markers of eosinophil activation. We analyzed ECP and EPX concentrations in nasal lavage fluids (NALF) of 378 neonates during their first 4 weeks of life. Inclusion criteria were a positive history of parental allergy and a positive skin prick test or specific IgE (RAST class > or = 2) against at least one out of a panel of common aeroallergens in one or both parents. Twenty-four infants with no history of parental allergy were used as controls. A volume of 2 ml of 0.9% saline was instilled into each nostril and immediately recovered by a suction device. ECP and EPX were analyzed by radioimmunoassay. In 65 samples of three consecutive lavages, EPX was detected in nine samples (13.8%) in the control group, whereas it was detected in 197/360 samples (54.7%) in the study population. The corresponding figures for ECP were 17/65 (26.2%) in the control group and 173/365 (47.4%) in the study group. Both proteins showed a skewed distribution (median/5-95th percentiles for ECP: 0 microg/l [0-69.4] and EPX: 6.6 microg/l [0-73.2]). The differences between the control group and the study group were statistically significant, regardless of the allergic disease of the parents. In children of allergic parents, activation proteins of the eosinophil granulocyte are released on the nasal mucosal surface in about 50% of the studied population at the age of 4 weeks. This early onset of eosinophil activation in the nasal respiratory epithelium may reflect a genetic predisposition to allergy or early exposure to allergens.

Off-label use of antipsychotic drugs

Despite the fact that most antipsychotics have only been formally evaluated for the treatment of schizophreniform disorder, schizophrenia, mania, and schizoaffective disorder (defined as "classical indications"), antipsychotics are widely used for the treatment of a broad range of symptoms and disorders. In this study, 173 patients who were having their prescriptions for antipsychotics filled at local pharmacies were interviewed. In 115 patients (66.5%), an antipsychotic was prescribed for off-label indications. Patients most often stated that they took antipsychotics as a tranquilizer or an anxiolytic. Neither gender, education, duration of treatment, nor efficacy of treatment showed an influence on the prescription practices for antipsychotics. In contrast, family status and side effects showed a significant influence. A classical indication was more often found in married and widowed patients than in unmarried or divorced ones. Patients in whom antipsychotics were prescribed for the treatment of schizophrenia, schizophreniform disorder, mania, or schizoaffective disorder experienced side effects more often than others. Age was also important for the indication of antipsychotics. Classical indications of antipsychotics were most often found in patients aged 30 to 49 years. In older patients (49-70 years), antipsychotics were almost exclusively used for off-label indications. In classical indications, clozapine was used more frequently (50%) than other antipsychotics. Melperone was primarily prescribed for off-label use.

A temperature-regulated replicon-based DNA expression system

We present a temperature-regulated, alphavirus replicon-based DNA expression system. The system is regulated by a viral temperature-sensitive RNA-dependent RNA replicase, creating a temperature-dependent RNA amplification loop. Because of this positive feedback, the system exhibits both low background and high inducibility. We observed 700-fold induction in transiently transfected cells, and over 104-fold induction in stably transfected cells. The high stringency of inducibility allowed the generation of stable cell lines expressing a highly toxic protein upon temperature shift. These data suggest that the present expression system could simplify bioprocess engineering strategies, especially in situations where the cloned protein has detrimental effects on host cell metabolism.

Efficient gene delivery into adult cardiomyocytes by recombinant Sindbis virus

Somatic gene therapy as a potential strategy for the treatment of myocardial diseases relies on an efficient gene transfer into cardiac muscle cells. The difficulty of delivering genes into adult cardiomyocytes exists not only in vivo but also in primary culture systems. Therefore, possibilities for ex vivo gene transfer and the in vitro study of physiological processes by reverse genetics are limited. We investigated the potential of an alphavirus-based vector system to transduce adult rat cardiomyocytes (ARC) in culture using a replication-deficient Sindbis virus (SIN) encoding beta-galactosidase (SIN-LacZ). Transduction efficiency depended on the virus concentration used, with expression of the reporter gene being detectable in up to 80% of cultured ARC as early as 24 h after infection. We observed a remarkably lower cytotoxicity of this viral vector in ARC than in other cells such as fibroblasts and neonatal cardiomyocytes. Additionally, no perceptible changes in the morphology of the nuclei or cytoskeleton were found in ARC 48 h after infection with SIN-LacZ. We conclude that SIN vectors are useful for gene delivery into adult cardiomyocytes and believe that improved versions of this viral system may be useful for cardiovascular gene therapy in the future.

Heterogeneity in hereditary pancreatitis

Hereditary pancreatitis (HP) is the most common form of chronic relapsing pancreatitis in childhood, and may account for approximately 25% of adult cases with chronic idiopathic pancreatitis. Recently, an arginine-histidine (R117H) mutation within the cationic trypsinogen gene was found in 5/5 families studied with HP. In this study we report on the results of linkage and direct mutational analysis for the common R117H mutation examined in 8 nonrelated families with hereditary pancreatitis. Two-point linkage analysis with the 7q35 marker D7S676, done initially in 4 families, yielded lod scores that were positive in 2, negative in one, and weakly positive in one. Direct mutational analysis of exon 3 of the cationic trypsinogen gene in 6 families showed that all symptomatic individuals tested were heterozygous for the R117H mutation. Also, several asymptomatic but at-risk relatives were found to be heterozygous for this mutation. Affected individuals in the remaining 2 families did not have the mutation. Radiation hybrid mapping using the Genebridge 4 panel assigned the trypsinogen gene to chromosome region 7q35, 2.9 cR distal to ETS WI-9353 and 3.8 cR proximal the dinucleotide repeat marker D7S676. The negative linkage and absence of the trypsinogen mutation in 2/8 families suggest locus heterogeneity in HP. Analysis of the R117H mutation is useful in identifying presymptomatic "at-risk" relatives and in genetic counseling. Also, it can be useful in identifying children and adults with isolated chronic idiopathic pancreatitis.

Familial multiple-system tauopathy with presenile dementia is localized to chromosome 17

An autosomal dominant presenile dementia affecting 39 individuals in a seven-generation, 383-member pedigree has been studied at Indiana University. In the affected members of this family, clinical symptoms occurred early in life, with an average age at onset of 48.8 years. The presenting clinical features include disequilibrium, neck stiffness, dysphagia, and memory loss. As the disease progresses, further cognitive decline, superior-gaze palsy, and dystaxia also are observed. The average duration from onset of symptoms to death is approximately 10 years. Neuropathologic studies of nine affected individuals showed neuronal loss in several areas of the CNS, as well as argentophilic tau-immunopositive inclusions in neurons and in oligodendroglia. A limited genomic screen by use of DNA samples from 28 family members localized the gene for this disorder to a 3-cM region on chromosome 17, between the markers THRA1 and D17S791. The gene for tau also was analyzed, through samples from the family.

Spheroid body myopathy revisited

Having reported spheroid body myopathy from Indiana (IN) inherited in an autosomal-dominant fashion several years ago, we now describe additional findings from the Oregon branch--briefly recorded earlier--and confirm earlier studies in another clinically affected IN member of this kinship demonstrating identical spheroid bodies within the myopathic muscle specimens. The spheroid bodies also contained increased amounts of desmin, alpha-B crystallin, and ubiquitin within muscle fibers. Our studies now have established that spheroid body myopathy is a member of the growing family of desminopathic neuromuscular conditions.

Mapping of the primary binding site of measles virus to its receptor CD46

The measles virus (MV) hemagglutinin binds to the complement control protein (CCP) CD46 primarily through the two external modules, CCP-I and -II. To define the residues involved in binding, 40 amino acids predicted to be solvent-exposed on the CCP-I-II module surface were changed to either alanine or serine. Altered proteins were expressed on the cell surface, and their abilities to bind purified MV particles, a soluble form of hemagglutinin (sH) and nine CD46-specific antibodies competing to different levels with sH attachment, were measured. All proteins retained, at least in part, MV and sH binding, but some completely lost binding to certain antibodies. Amino acids essential for binding of antibodies weakly or moderately competing with sH attachment are situated in the membrane-distal tip of CCP-I, whereas residues involved in binding of strongly sH competing antibodies cluster in the center of CCP-I (Arg-25, Asp-27) or in CCP-II (Arg-69, Asp-70). Both clusters face the same side of CCP-I-II and map close to amino acid exchanges impairing sH binding (E11A, R29A, P39A, and D70A) or MV binding (D70A and E84A) and to a six-amino acid loop, previously shown to be necessary for sH binding.

A 3D model for the measles virus receptor CD46 based on homology modeling, Monte Carlo simulations, and hemagglutinin binding studies

The two terminal complement control protein (CCP) modules of the CD46 glycoprotein mediate measles virus binding. Three-dimensional models for these two domains were derived based on the NMR structures of two CCP modules of factor H. Both CD46 modules are about 35 A long, and form a five-stranded antiparallel beta-barrel structure. Monte Carlo simulations, sampling the backbone torsion angles of the linker peptide and selecting possible orientations on the basis of minimal solvent-exposed hydrophobic area, were used to predict the orientation of CCP-I relative to CCP-II. We tested this procedure successfully for factor H. For CD46, three clusters of structures differing in the tilt angle of the two domains were obtained. To test these models, we mutagenized the CCP modules. Four proteins, two without an oligosaccharide chain and two with mutated short amino acid segments, reached the cell surface efficiently. Only the protein without the CCP-I oligosaccharide chain maintained binding to the viral attachment protein hemagglutinin. These results are consistent with one of our models and suggest that the viral hemagglutinin does not bind at the membrane-distal tip of CD46, but near the concave CCP-II interface region.

Random Worlds and Maximum Entropy

Given a knowledge base KB containing first-order and statistical facts, we consider a principled method, called the random-worlds method, for computing a degree of belief that some formula Phi holds given KB. If we are reasoning about a world or system consisting of N individuals, then we can consider all possible worlds, or first-order models, withdomain {1,...,N} that satisfy KB, and compute thefraction of them in which Phi is true. We define the degree of belief to be the asymptotic value of this fraction as N grows large. We show that when the vocabulary underlying Phi andKB uses constants and unary predicates only, we can naturally associate an entropy with each world. As N grows larger,there are many more worlds with higher entropy. Therefore, we can usea maximum-entropy computation to compute the degree of belief. This result is in a similar spirit to previous work in physics and artificial intelligence, but is far more general. Of equal interest to the result itself are the limitations on its scope. Most importantly, the restriction to unary predicates seems necessary. Although the random-worlds method makes sense in general, the connection to maximum entropy seems to disappear in the non-unary case. These observations suggest unexpected limitations to the applicability of maximum-entropy methods.