Statistical methods for studying disease subtype heterogeneity

A fundamental goal of epidemiologic research is to investigate the relationship between exposures and disease risk. Cases of the disease are often considered a single outcome and assumed to share a common etiology. However, evidence indicates that many human diseases arise and evolve through a range of heterogeneous molecular pathologic processes, influenced by diverse exposures. Pathogenic heterogeneity has been considered in various neoplasms such as colorectal, lung, prostate, and breast cancers, leukemia and lymphoma, and non‐neoplastic diseases, including obesity, type II diabetes, glaucoma, stroke, cardiovascular disease, autism, and autoimmune disease. In this article, we discuss analytic options for studying disease subtype heterogeneity, emphasizing methods for evaluating whether the association of a potential risk factor with disease varies by disease subtype. Methods are described for scenarios where disease subtypes are categorical and ordinal and for cohort studies, matched and unmatched case–control studies, and case–case study designs. For illustration, we apply the methods to a molecular pathological epidemiology study of alcohol intake and colon cancer risk by tumor LINE‐1 methylation subtypes. User‐friendly software to implement the methods is publicly available. Copyright © 2015 John Wiley & Sons, Ltd.     

Mapping air pollution by biological monitoring in the metropolitan Tel Aviv area

Conventional environmental monitoring is not surrogate of personal exposure. In contrast, biomonitoring provides information on the presence of substances in the human body, making it highly relevant to the assessment of exposure to toxic substances. Induced sputum (IS) is a noninvasive technique for detecting inflammation and reflecting particulate matter content in the airways. In this study, we mapped particulate matter dispersion in metropolitan Tel Aviv by both biomonitoring techniques employing IS samples and by environmental monitoring. All adults referred to the Pulmonary Lab for respiratory symptom evaluation in 2007 and in 2009 were enrolled. Pulmonary function tests were performed by conventional methods. Particulate size distribution in IS was analyzed, and maps of air pollution were created. Biomonitoring was more informative and enabled mapping of wider areas. Integration of biomonitoring and environmental monitoring should be considered in forming public health policy on containment of airborne particles of toxic substances.     

Epidural abscess in the spine extended from pulmonary zygomycosis during consolidation chemotherapy for acute lymphoblastic leukemia

A 37-year-old woman with acute lymphoblastic leukemia developed fever and pneumonia during persistent neutropenia after consolidation chemotherapy. Pneumonia was rapidly followed by the formation of abscess in adjacent subcutaneous tissues, muscles and bones. She subsequently developed sudden onset of paraplegia and loss of all sensation below Th4. Epidural abscess was detected by MRI. Emergency drainage was performed, but the patient died 4 days after the operation. Rhizopus oryzae grew from culture of the epidural abscess. Since the incidence of zygomycosis appears to have increased over the recent years, clinicians should be aware of the possibility of zygomycosis in case of any infection that is resistant to antibiotics.     

Oculopharyngeal muscular dystrophy associated with dementia

We report genetically confirmed heterozygote oculopharyngeal muscular dystrophy (OPMD) accompanied by dementia, suggesting a possible causal association between OPMD and dementia. The proband first noticed bilateral ptosis, dysphagia, and proximal dominant muscle weakness in the lower extremities at age 53. Ten years later, she was found to have dementia with a score of 10/30 on the mini-mental state examination (MMSE). On PABPN1 gene analysis, the GCN repeat was expanded 17 times in one allele. In addition, the proband's younger brother exhibited myopathy and dementia. To our knowledge, this is the first report of genetically confirmed heterozygote OPMD associated with dementia.     

Intron sequences from the CCT7 gene exhibit diverse evolutionary histories among the four lineages within the Babesia microti-group, a genetically related species complex that includes human pathogens

Babesia microti, the primary causal agent of human babesiosis in North America, was thought to distribute in Europe in association with ixodid ticks and rodents. Recent analyses of β-tubulin and the eta subunit of the chaperonin-containing t-complex protein 1 (CCT7) genes revealed discrete clusters (a species-complex comprised of at least 4 taxa for the U.S., Kobe, Munich, and Hobetsu). To further assess the micro-evolutionary history and genetic variability within the taxon, we combined a set of 6 introns from the CCT7 gene to use as a rapidly evolving DNA marker. Phylogenetic and comparative sequence analyses subdivided the U.S. taxon into 3 geographic subclades--North America, western to central Eurasia, and northeastern Eurasia (≥ 98% bootstrap supports for each node). The Kobe taxon, which occurs only in a few geographic foci of Japan, could further be subdivided into 2 subgroups (100% support). The Munich and Hobetsu taxa, common to Europe and Japan, respectively, exhibited little or no pairwise sequence divergence among geographically diverse samples, suggesting an extreme population bottleneck during recent history. Despite the small sample size, this study provides a better understanding of the micro-evolutionary relationships and the genetic variability present within each lineage of the B. microti-group.     

Expression and localisation of vascular ribonucleases in endothelial cells

The functions of extracellular RNA in the vascular system as new procoagulatory and permeability-increasing factor in vivo and in vitro were shown to be counteracted by pancreatic type RNase1. Based on the identification of RNase1 in plasma and serum, it is proposed that the enzyme is expressed by vascular cells to contribute in the regulation of extracellular RNA. It is demonstrated that RNase1 and RNase5 (also termed angiogenin) were differentially expressed in various types of endothelial cells, whereby human umbilical vein endothelial cells (HUVEC) expressed and released the highest concentration of active RNase1. Expression and release of RNase5 were similar in all types of endothelial cells tested. Both RNases were constitutively produced and secreted, whereby a portion of RNase1, but not RNase5, was stored in Weibel-Palade bodies, co-localising with von Willlebrand factor and P-selectin. Accordingly, immediate release of RNase1 from these granules was demonstrated in vitro and in vivo using Weibel-Palade body exocytosis-inducing agents. Additionally, extracellular RNA or poly:IC (but not DNA) induced this short-term release of RNase1. Our results indicate that vascular RNase1 and RNase5 are mainly produced by vascular endothelial cells and can serve, depending on the vascular bed, different functions in vascular homeostasis and endothelial cell responses.