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Biomedical subjects

R O'Reilly

Publications and source records attributed to R O'Reilly.

At least 19 recordsLinked to original sources
PubMed2004

Incidental neurodevelopmental episodes in the etiology of schizophrenia: an expanded model involving epigenetics and development.

Epidemiological data favors genetic predisposition for schizophrenia, a common and complex mental disorder in most populations. Search for the genes involved using candidate genes, positional cloning, and chromosomal aberrations including triplet repeat expansions have established a number of susceptibility loci and genomic sites but no causal gene(s) with a proven mechanism of action. Recent genome-wide gene expression studies on brains from schizophrenia patients and their matched controls have identified a number of genes that show an alteration in expression in the diseased brains. Although it is not possible to offer a cause and effect association between altered gene expression and disease, such observations support a neurodevelopmental model in schizophrenia. Here, we offer a mechanism of this disease, which takes into account the role of developmental noise and diversions of the neural system. It suggests that the final outcome of a neural developmental process is not fixed and exact. Rather it develops with a variation around the mean. More important, the phenotypic consequence may cross the norm as a result of fortuitous and/or epigenetic events. As a result, a normal genotype may develop as abnormal with a disease phenotype. More important, susceptible genotypes may have reduced penetrance and develop as a normal phenocopy. The incidental episodes in neurodevelopment will explain the frequency of schizophrenia in most populations and high discordance of monozygotic twins.

Brain↗
PubMed2002

Epigenetic contributors to the discordance of monozygotic twins.

Human monozygotic (MZ) twins estimated to occur once in 250 live births, result from an errant decision by embryonic cell(s) to develop as separate embryos. They are considered genetically identical and any phenotypic discordance between them has been used to implicate the role of environment. More recent literature, however, has questioned these assumptions but the frequency and the nature of any genetic discordance between MZ twins remains poorly understood. We will review published cases of phenotypic and genetic discordance between monozygotic twins to argue that not all discordance between such twins is due to differences in environment. The causes of reduced concordance between MZ twins remains poorly understood. They represent among the challenging aspects of the genetics of complex multi-factorial traits and diseases. A number of questions regarding the published results on MZ twins merit a re-assessment in the light of modern molecular insight of the human genome. Such an assessment is needed in directing future studies on MZ twins. In particular, we will deal with the origin, development, genetic and epigenetic factors that may have implications in discordance of the MZ twin pairs.

DNA Methylation↗
PubMed2001

Traditional Maori food preparation methods and food safety.

Descriptions were obtained from Maori elders knowledgeable in traditional methods for the processing of Tiroi (mussels and Puha), Kina (sea urchins), Kanga Kopiro (fermented maize) and Titi (muttonbird). Information for a number of variations of each method was transformed into process flow charts, and these charts were analysed using a HACCP-based approach. Two of the processes (Kanga Kopiro and Titi) were found to be likely to produce safe foods as Kanga Kopiro undergoes an acid fermentation and Titi preparation involves significant cooking steps. However, the information regarding Tiroi and Kina processing did not supply the necessary data to identify definitely whether fermentations were involved, and if they were, what kind they may be. New Zealand has only experienced one outbreak of botulism, and this was associated with the consumption of Tiroi. It is, therefore, desirable to identify the processes occurring in these foods where the nature of these processes is not understood in order to facilitate their safe future production.

Consumer Product Safety↗
PubMed1999

Id1 and Id3 are required for neurogenesis, angiogenesis and vascularization of tumour xenografts.

Id proteins may control cell differentiation by interfering with DNA binding of transcription factors. Here we show that targeted disruption of the dominant negative helix-loop-helix proteins Id1 and Id3 in mice results in premature withdrawal of neuroblasts from the cell cycle and expression of neural-specific differentiation markers. The Id1-Id3 double knockout mice also display vascular malformations in the forebrain and an absence of branching and sprouting of blood vessels into the neuroectoderm. As angiogenesis both in the brain and in tumours requires invasion of avascular tissue by endothelial cells, we examined the Id knockout mice for their ability to support the growth of tumour xenografts. Three different tumours failed to grow and/or metastasize in Id1+/- Id3-/- mice, and any tumour growth present showed poor vascularization and extensive necrosis. Thus, the Id genes are required to maintain the timing of neuronal differentiation in the embryo and invasiveness of the vasculature. Because the Id genes are expressed at very low levels in adults, they make attractive new targets for anti-angiogenic drug design.

Animals↗
PubMed1997

Correction of defective expression in MHC class II deficiency (bare lymphocyte syndrome) cells by retroviral transduction of CIITA.

Retrovirus-mediated gene transfer was used to restore expression to MHC class II-negative patient cells from complementation group A(II) of MHC class II immunodeficiency or bare lymphocyte syndrome (BLS). The cells of these patients do not transcribe MHC class II genes due to a defect in the trans-acting factor, CIITA. We constructed a vector, pGAG/Ii-CIITA, with the MHC class II-associated invariant chain promoter driving CIITA expression. Cocultivation with the virus producer line was consistently shown to be the optimal method for infection of all cell types. The induction of MHC class II expression after virus infection was rapid, and high levels of expression were achieved in cell lines within 1 wk of infection. In addition, expression was easily detectable even in peripheral blood cells of a BLS patient within a few days. Cell lines maintained in vitro for several months remained positive, and the proportion of cells with surface expression of DR was correlated with the number of integrated proviruses. Moreover, transduced B lymphoblastoid cell lines readily established tumors in CB17-scid/scid mice, and the MHC class II-positive cells demonstrated a clear competitive advantage in vivo. Ultimately, we hope to use this transduction system to restore normal immune function to a BLS patient for which no other therapeutic option currently exists.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1994

Stereochemical aspects of warfarin drug interactions: use of a combined pharmacokinetic-pharmacodynamic model.

OBJECTIVE: To apply a combined pharmacokinetic-pharmacodynamic model to data from warfarin drug interaction studies. METHODS: The pharmacokinetic model for warfarin enantiomers combined a common first-order absorption process with individual clearance and volume of distribution values and is based on unbound drug. The complete pharmacodynamic model comprised two components: that involving inhibition of prothrombin complex activity (PCA) synthesis described by a sigmoid maximum effect (Emax) model and that relating temporal changes in PCA to synthesis and degradation. The combined model was applied to prothrombin time and plasma concentration-time data obtained after oral administration of single doses of racemic warfarin to healthy subjects either alone or during multiple dosing with the metabolic enzyme inhibitor phenylbutazone or the inducer secobarbital. RESULTS: The five parameters associated with the complete pharmacodynamic model were kd (0.054 +/- 0.014 hr-1), the degradation rate constant of PCA; Cu50,S (0.0026 +/- 0.0015 mg.L-1) and Cu50,R (3.45 +/- 4.20 mg.L-1), the unbound concentrations of (S)- and (R)-warfarin required to produce a 50% reduction in PCA synthesis if administered individually; gamma (0.90 +/- 0.23), the slope parameter in the sigmoid Emax model; and td (8.2 +/- 0.3 hours), the observed delay in the onset of warfarin anticoagulant response. CONCLUSIONS: These findings qualitatively confirm the known potency difference between warfarin enantiomers. Furthermore, although phenylbutazone and secobarbital altered the pharmacokinetics of warfarin, these compounds do not appear to influence its pharmacodynamics. Simulation studies indicate that, after racemate administration, the continual presence of the more potent (S)-enantiomer precludes accurate assessment of Cu50,R. Analysis indicates that use of racemic (rather than enantiomer) warfarin concentration data in drug interaction studies may lead to misinterpretation of pharmacodynamic data.

Blood Coagulation↗
PubMed1994

Phase I study of recombinant human interleukin-1 beta (rhIL-1 beta) in patients with bone marrow failure.

The administration of recombinant human interleukin-1 beta (rhIL-1 beta) stimulates pluripotent cell growth and reduces mortality from infection in animal models. In this phase I trial, rhIL-1 beta (0.02-0.50 microgram/kg) was administered by 30-minute intravenous infusion once daily for 2 or 5 consecutive days. The dose was escalated with the subsequent cycle in the same patient if no hematologic response was observed. Nineteen patients with severe bone marrow failure received 60 courses of IL-1 beta. Diagnoses included autologous bone marrow transplant (BMT) (n = 5), allogeneic BMT (n = 7) or idiopathic aplastic anemia (n = 6) and 1 patient with chronic myeloid leukemia. Toxicities included fever (89%), chills (85%), hypertension (89%), hypotension (57%) and headache (95%). No complications were life-threatening and all either spontaneously resolved or were managed pharmacologically. In 8 of 19 patients there was an acute, transient increase in neutrophil counts. In 2 patients there was a transient increase in platelet count; however, no durable, clinically significant effects on peripheral blood counts were observed. In conclusion, administration of rhIL-1 beta in this population of patients had limited efficacy and moderate toxicity.

Adolescent↗