The use of multiple hypothesis-generating methods in an outbreak investigation of Escherichia coli O121 infections associated with wheat flour, Canada 2016-2017.

A Canadian outbreak investigation into a cluster of Escherichia coli O121 was initiated in late 2016. When initial interviews using a closed-ended hypothesis-generating questionnaire did not point to a common source, cases were centrally re-interviewed using an open-ended approach. The open-ended interviews led cases to describe exposures with greater specificity, as well as food preparation activities. Data collected supported hypothesis generation, particularly with respect to flour exposures. In March 2017, an open sample of Brand X flour from a case home, and a closed sample collected at retail of the same brand and production date, tested positive for the outbreak strain of E. coli O121. In total, 76% (16/21) of cases reported that they used or probably used Brand X flour or that it was used or probably was used in the home during their exposure period. Crucial hypothesis-generating techniques used during the course of the investigation included a centralised open-ended interviewing approach and product sampling from case homes. This was the first outbreak investigation in Canada to identify flour as the source of infection.

Spotlight on middle childhood: Rejuvenating the 'forgotten years'.

Middle childhood, from six to 12 years of age, is often known as the 'forgotten years' of development because most research is focused on early childhood development or adolescent growth. However, middle childhood is rich in potential for cognitive, social, emotional and physical advancements. During this period, the brain is actively undergoing synaptic pruning and, as such, is constantly becoming more refined, a process that is heavily dependent on a child's environment. This discovery opens the door to optimizing the experiences a child needs to provide themselves with a strong foundation for adulthood. The present article reviews the neurological changes that occur in middle childhood, their impact on overall development and how to implement this knowledge to augment a child's capabilities.

La période intermédiaire de l'enfance, de six à 12 ans, est souvent connue comme « les années oubliées ¼ du développement, car une bonne partie de la recherche est axée sur le développement de la petite enfance ou la croissance à l'adolescence. Cependant, cette période est riche en potentiel sur le plan du progrès cognitif, social, affectif et physique. Le cerveau subit activement un élagage synaptique et devient donc de plus en plus raffiné, un processus qui dépend lourdement de l'environnement de l'enfant. Cette découverte ouvre la porte à l'optimisation des expériences que vit l'enfant afin d'établir des assises solides pour l'âge adulte. Le présent article aborde les changements neurologiques qui se produisent pendant la période intermédiaire de l'enfance, leurs répercussions sur le développement global et la mise en œuvre de ces connaissances pour accroître les capacités de l'enfant.

Are we making a real difference? Update on 'hidden mortality' in the management of congenital diaphragmatic hernia.

Reports of improved survival rates for cases of congenital diaphragmatic hernia (CDH) patients have prevailed in the literature over the past 10 years. These improvements have been attributed to advances in medical management in the postnatal period. However, further inquiries into the true survival of CDH patients through population-based studies have revealed that the reported increase in survival outcomes, which are often single institution-based reports, are confounded by case selection bias which fails to consider those CDH patients who do not reach the referral centers. This apparent discrepancy between population-based and institution-based statistics raises the question of 'hidden mortality' and the role it plays in both research and clinical medicine. In this review we will examine the reported survival outcomes of CDH from both institution- and population-based perspectives and explore the presence and implications of hidden mortality on research methodology and clinical practice.

Absolute vs relative improvements in congenital diaphragmatic hernia survival: what happened to "hidden mortality".

PURPOSE: The aim of this study is to determine if there has been a true, absolute, or apparent relative increase in congenital diaphragmatic hernia (CDH) survival for the last 2 decades. METHOD: All neonatal Bochdalek CDH patients admitted to an Ontario pediatric surgical hospital during the period when significant improvements in CDH survival was reported (from January 1, 1992, to December 31, 1999) were analyzed. Patient characteristics were assessed for CDH population homogeneity and differences between institutional and vital statistics-based population survival outcomes. SAS 9.1 (SAS Institute, Cary, NC) was used for analysis. RESULT: Of 198 cohorts, demographic parameters including birth weight, gestational age, Apgar scores, sex, and associated congenital anomalies did not change significantly. Preoperative survival was 149 (75.2%) of 198, whereas postoperative survival was 133 (89.3%) of 149, and overall institutional survival was 133 (67.2%) of 198. Comparison of institution and population-based mortality (n = 65 vs 96) during the period yielded 32% of CDH deaths unaccounted for by institutions. Yearly analysis of hidden mortality consistently showed a significantly lower mortality in institution-based reporting than population. CONCLUSION: A hidden mortality exists for institutionally reported CDH survival rates. Careful interpretation of research findings and more comprehensive population-based tools are needed for reliable counseling and evaluation of current and future treatments.

The utility of latex agglutination assays in the diagnosis of pediatric viral gastroenteritis.

To design a rapid and efficient protocol for processing pediatric stool specimens, the authors used 434 specimens to evaluate two commercial latex assays to detect rotavirus (Meritec-Rotavirus and Rotalex) and one to detect adenovirus (Adenolex). Rotavirus latex assay results were compared with electron microscopic examination and adenovirus latex assay results with virus culture. Ninety-two specimens (21%) were positive for rotavirus and 28 (6.5%) for adenovirus; 5 (1%) had both viruses. The sensitivity, specificity, positive predictive values, and negative predictive values for the three assays were, respectively, as follows: Meritec-Rotavirus (97%, 99%, 97%, 99%), Rotalex (91%, 99%, 94%, 98%), and Adenolex (46%, 99%, 77%, 97%). For primary rotavirus screening, the Meritec-Rotavirus and Rotalex latex assays offer a good alternative to electron microscopic examination. For primary adenovirus screening, the low sensitivity of the Adenolex latex assay precludes its use as a routine screen. Its excellent specificity, however, makes it a useful tool for culture confirmation.

Morphological substrates of infantile spasms: studies based on surgically resected cerebral tissue.

Extensive surgical resections of neocortical cerebral tissue (including hemispherectomies) from 13 infants and children with infantile spasms showed that 12 of 13 specimens contained either malformative and dysplastic lesions of the cortex and white matter (sometimes with associated hamartomatous proliferation of globular cells), or destructive lesions possibly acquired as a result of anoxic-ischemic injury, or a combination of the two. In brain tissue from 4 patients, coarse neuronal cytoplasmic fibrils resembling neurofibrillary tangles were seen in areas of dysplastic brain on silver-stained (Bielschowsky technique) sections. Immunohistochemical (immunoperoxidase) study of cortical lesions containing globular cells employing primary antibodies to glial fibrillary acidic protein and synaptophysin as markers of astrocytic and neuronal differentiation, respectively, revealed that many cells showed astrocytic and/or neuronal features, suggesting the local proliferation of primitive or multipotential neuroectodermal cells as one substrate for this seizure disorder. Morphological abnormalities of a severe degree and wide extent in the resected tissue (e.g., in one patient with hemimegalencephaly) often showed features to suggest that they may represent variants of tuberous sclerosis. These most likely result from abnormal movement and/or local proliferation of neuroectodermal precursors that have migrated from the germinal matrix to the cortical mantle. Cellular, molecular and neurophysiological study of these abnormalities is likely to yield information about basic molecular mechanisms of brain malformation and injury important in the pathogenesis of infantile spasms and other forms of focal or generalized epilepsy.

In situ hybridization of calcium/calmodulin dependent protein kinase II and tau mRNAs; species differences and relative preservation in Alzheimer's disease.

Abnormal phosphorylation of the microtubule associated protein tau component of neurofibrillary tangles (NFTs) in Alzheimer's disease (AD) may result from alterations in protein kinase expression. Calcium/calmodulin dependent protein kinase II (CaM kinase II) has been shown to phosphorylate tau in vitro in such a way to decrease its electrophoretic mobility. A68, apparently a modified form of tau in AD brain, also shows abnormal phosphorylation and slower mobility than tau. To further examine the role of CaM kinase II in AD, in situ hybridization studies were performed on tissues from rat, monkey and human to examine and compare the patterns of CaM kinase II mRNA expression in different brain regions. The most notable differences among the three species were observed in dendrites in layer I of isocortex, in the molecular layer of the dentate gyrus and stratum radiatum and stratum lacunosum-moleculare in hippocampus, where hybridization was detected in rat, but not in monkey or human brain. In addition, comparisons between tau and CaM kinase II mRNA expression were made in tissue from normal aged adults and AD patients, especially in areas prone to NFT formation. CaM kinase II and tau mRNAs were co-expressed in many neuronal populations, both those which are prone to NFT formation as well as those which are rarely affected by AD changes. No major differences in the relative abundance of either CaM kinase II or tau mRNA within particular neuronal populations was noted between normal aged and AD brain. Diminished hybridization was associated with serve neuronal pathology and cell loss.

The SENEX Project: knowledge representation in molecular pathology.

SENEX is a computer program for students, educators, and research investigators in the domain of molecular pathology. The application allows an individual to ask a sequence of questions in a single interactive session, thereby facilitating the development and testing of several hypotheses in a short period of time. Graphical representations of molecules and molecular events help enable individuals to grasp spatial and functional relationships (and in the future, temporal relationships) among molecules, cellular compartments, and cell regions. Fairly simple but well-defined reasoning capabilities allow an individual to ask sophisticated questions and to predict novel molecular events or pathways. SENEX contains information about: 1) molecules and the motifs that impart function to these molecules; 2) molecular events; 3) cell-specific expression of genes; 4) disease processes. SENEX is being developed through object-oriented programming in a portable programming environment supported by COMMON LISP and the COMMON LISP INTERFACE MANAGER.

SENEX: a computer-based representation of cellular signal transduction processes in the central nervous system.

The SENEX project is exploring knowledge representation in the neurobiology of ageing through object-oriented programming. SENEX is built from a classification structure of biologic entities and significant relationships among them. For example, an enzyme is an entity and an enzymatic reaction is a relationship among enzyme, cofactor(s), substrate(s) and product(s). There are currently 2600 classes of entities and 50 classes of relationships in SENEX. The class structure serves several functions. One function is to interrelate general and specific categories of molecular and morphologic entities. For example, tyrosine kinase and serine/threonine kinase are specific types of the more general class of protein kinase enzymes. Another function of the class structure is to serve as a network through which inheritance of attributes may occur. For example, the attribute 'subunits' is inherited by all subclasses of the general class multisubunit protein. Information may be accessed through links established in the class structure and through links relating one object as part of another. Relationships form the basis of separate modules within SENEX. This paper describes the types of relationships currently used and planned in the representation of age-related changes in cellular signal transduction processes of mammalian central nervous systems. We also describe tools for specific retrieval of relationships and for tracing links in complex reaction cascades. Application of these tools to identifying possible signal transduction pathways to guide further exploration through experimentation is discussed.

Neuropathologic findings after bone marrow transplantation: an autopsy study.

Clinicopathologic records and neuropathologic tissues of 109 patients who underwent necropsy after treatment with bone marrow transplantation (BMT) were examined. Underlying disorders included leukemia (70), aplastic anemia (25), solid tumors (7), lymphoma (5), Hodgkin's disease (1) and Wiskott-Aldrich syndrome (1). There were 34 females and 75 males, ranging in age from 2 to 56 years. Survival after transplantation averaged 3.6 months. The most common findings were cerebrovascular lesions (29), including hematomas, hemorrhagic necrosis, and infarcts. Central nervous system infections comprised the next most common finding, including 10 fungal and four bacterial infections. A recurrence of underlying malignancy for which transplant had been performed occurred in five patients. Leukoencephalopathy of varying severity was found in eight patients, half of whom had received intrathecal chemotherapy and/or cranial radiation. Patients with systemic graft-versus-host disease had a variety of nonspecific neuropathologic findings in the nervous system; however, nearly half (44%) showed no detectable changes. Other nonspecific alterations included hypoxic/ischemic changes, vascular siderocalcinosis, and neuroaxonal spheroids (associated with hemorrhage or necrosis). These findings provide a guide as to likely causes of a neurologic syndrome in a patient who has undergone BMT, and can be compared with neuropathologic findings in other forms of immunosuppression.

Abnormalities of peripheral nerve in patients with human immunodeficiency virus infection.

The purpose of this study was to assess systematically morphology of peripheral nerves from patients with human immunodeficiency virus infection (acquired immunodeficiency syndrome [AIDS] and AIDS-related complex) examined at autopsy. Sural nerve specimens were taken from 25 patients (mean age 44 years) and evaluated by routine procedures used in our laboratory. In 13 cases no detectable abnormality was seen. Twelve patients (48%) showed loss of myelinated fibers with disproportionately greater loss of large myelinated fibers. Three of these patients showed severe myelinated fiber loss; 2 had no documented symptoms and no other known predisposing factors for a peripheral neuropathy. Changes suggestive of wallerian degeneration were occasionally seen, as were epineurial and endoneurial inflammatory infiltrates. Segmental demyelination was not identified in any nerve examined. Electron microscopy revealed thickened basement membranes around small blood vessels, Schwann cells, and fibroblasts. Peripheral nerve abnormalities in patients with AIDS or ARC are frequent and their pathogenesis remains unclear.

Evidence for human immunodeficiency virus (HIV) infection of the brain in a patient with aplastic anemia.

A young female patient with a long history of intravenous drug abuse died after a fulminant course of aplastic anemia. At postmortem examination, she was found to have multinucleate giant cells and immunocytochemical evidence of human immunodeficiency virus (HIV) infection of the central nervous system. This case raises the possibility that HIV infection contributed to the patient's aplastic anemia, and suggests that HIV-associated giant cells might be found retrospectively or prospectively within the brains of patients who die of conditions other than those narrowly defined as acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC). It furthermore emphasizes that HIV infection of the nervous system is not necessarily accompanied by clinically apparent neurological disease.

Focal pontine leukoencephalopathy in a patient with the Shwachman-Diamond syndrome.

A 35-year-old woman who died after a long history of an illness consistent with Shwachman-Diamond Syndrome, was found to have extensive calcified necrotizing lesions confined to the pontocerebellar fibers of the basis pontis. The possible relationship of this recently described lesion to the patient's immunosuppressed state and/or other systemic metabolic disturbances is discussed.

Biochemical evidence for an endocytically inactive population of lysosomes.

The peroxidase dependent, diaminobenzidine (DAB) density shift procedure was applied to the characterization of lysosomes from Chinese hamster ovary (CHO) cells. Peroxidase activity was localized in lysosomes by a 15-18 h internalization period. After treatment with DAB, the distribution of peroxidase activity in Percoll gradients was shifted, as a population, to a higher density. A bimodal distribution which included a low density population was observed for the native lysosomal enzyme beta-hexosaminidase after DAB treatment. A second lysosomal enzyme, alpha-fucosidase, was strongly inhibited by DAB treatment with the residual activity corresponding in distribution to the light beta-hexosaminidase population. The occurrence of a low density lysosomal population after the DAB procedure suggests the existence of an endocytically inactive lysosomal population in fibroblasts. Probable physiological candidates for such a population are discussed.