The genotype-phenotype landscape of familial amyotrophic lateral sclerosis in Australia.

Amyotrophic lateral sclerosis (ALS) is a clinically and genetically heterogeneous fatal neurodegenerative disease. Around 10% of ALS cases are hereditary. ALS gene discoveries have provided most of our understanding of disease pathogenesis. We aimed to describe the genetic landscape of ALS in Australia by assessing 1013 Australian ALS patients for known ALS mutations by direct sequencing, whole exome sequencing or repeat primed polymerase chain reaction. Age of disease onset and disease duration were used for genotype-phenotype correlations. We report 60.8% of Australian ALS families in this cohort harbour a known ALS mutation. Hexanucleotide repeat expansions in C9orf72 accounted for 40.6% of families and 2.9% of sporadic patients. We also report ALS families with mutations in SOD1 (13.7%), FUS (2.4%), TARDBP (1.9%), UBQLN2 (.9%), OPTN (.5%), TBK1 (.5%) and CCNF (.5%). We present genotype-phenotype correlations between these genes as well as between gene mutations. Notably, C9orf72 hexanucleotide repeat expansion positive patients experienced significantly later disease onset than ALS mutation patients. Among SOD1 families, p.I114T positive patients had significantly later onset and longer survival. Our report highlights a unique spectrum of ALS gene frequencies among patients from the Australian population, and further, provides correlations between specific ALS mutations with disease onset and/or duration.

The gene for hereditary sensory neuropathy type I (HSN-I) maps to chromosome 9q22.1-q22.3.

Hereditary sensory neuropathy type I (HSN-I, also known as hereditary sensory and autonomic neuropathy type I (HSAN-I), or hereditary sensory radicular neuropathy) is an autosomal dominant disorder that is the most common of a group of degenerative disorders of sensory neurons. HSN-I was initially recognized as a disease that produced mutilating ulceration leading to amputation of digits (Fig. 1). It was given names such as familial ulcers with mutilating lesions of the extremities and perforating ulcers with osseous atrophy. The disease involves a progressive degeneration of dorsal root ganglion and motor neurons, leading to distal sensory loss and later distal muscle wasting and weakness and variable neural deafness. Sensory deficits include loss of all modalities, particularly loss of sensation to pain and temperature. Skin injuries may lead to chronic skin ulcers, osteomyelitis, and extrusion of bone fragments, especially the metatarsals. Onset of symptoms is in the second or later decades. We undertook a genome screen using linkage analysis in four Australian HSN-I kindreds. We now show that the HSN1 gene maps to an 8-centiMorgan (cM) region flanked by D9S318 and D9S176 on chromosome 9q22.1-q22.3. Multipoint linkage analysis suggests a most likely location at D9S287, within a 4.9-cM confidence interval.

Cyclooxygenase- and lipoxygenase-mediated DNA damage.

Cancer is a disease of aging, and so with the increasing age of the US population, the incidence of cancer is also increasing. Furthermore the global burden of cancer continues to increase largely because of aging and growth of the world population together with increasing smoking rates in economically developing countries. Tumor formation is critically dependent upon two processes--initiation and progression. The initiation step is mediated by DNA damage, which causes activating mutations in proto-oncogenes and inactivation of tumor suppressor genes in many cancers. This is then thought to facilitate tumor progression and metastasis. Cyclooxygenase-2 (COX-2) is upregulated at an early stage in tumorigenesis and has been implicated as an important mediator of proliferation through the increased formation of bioactive arachidonic acid (AA) metabolites such as prostaglandin E(2). Significantly, we have found that COX-2-mediated AA metabolism also results in the formation of heptanone-etheno (Hε)-DNA adducts. Furthermore, we showed that the Hε-DNA adducts arose from the reaction of DNA with the lipid hydroperoxide-derived bifunctional electrophile, 4-oxo-2(E)-nonenal (ONE). Similarly, 5-lipoxoygenase-mediated AA metabolism also results in the formation of ONE-derived DNA adducts. The resulting Hε-DNA adducts are highly mutagenic in mammalian cell lines suggesting that these pathways could be (in part) responsible for the somatic mutations observed in tumorigenesis. As approximately 80% of cancers arise from somatic mutations, this provides an additional link between the upregulation of COX-2 and tumorigenesis.

A genome screen of 35 bipolar affective disorder pedigrees provides significant evidence for a susceptibility locus on chromosome 15q25-26.

Bipolar affective disorder is a heritable, relatively common, severe mood disorder with lifetime prevalence up to 4%. We report the results of a genome-wide linkage analysis conducted on a cohort of 35 Australian bipolar disorder families which identified evidence of significant linkage on chromosome 15q25-26 and suggestive evidence of linkage on chromosomes 4q, 6q and 13q. Subsequent fine-mapping of the chromosome 15q markers, using allele frequencies calculated from our cohort, gave significant results with a maximum two-point LOD score of 3.38 and multipoint LOD score of 4.58 for marker D15S130. Haplotype analysis based on pedigree-specific, identical-by-descent allele sharing, supported the location of a bipolar susceptibility gene within the Z(max-1) linkage confidence interval of 17 cM, or 6.2 Mb, between markers D15S979 and D15S816. Non-parametric and affecteds-only linkage analysis further verified the linkage signal in this region. A maximum NPL score of 3.38 (P=0.0008) obtained at 107.16 cM (near D15S130), and a maximum two-point LOD score of 2.97 obtained at marker D15S1004 (affecteds only), support the original genome-wide findings on chromosome 15q. These results are consistent with four independent positive linkage studies of mood and psychotic disorders, and raise the possibility that a common gene for susceptibility to bipolar disorder, and other psychiatric disorders may lie in this chromosome 15q25-26 region.

A novel TARDBP mutation in an Australian amyotrophic lateral sclerosis kindred.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that causes loss of motor neurons. A pathological hallmark of ALS is the presence of ubiquitinated TAR DNA binding protein (TDP-43) inclusions in the cytoplasm of affected cells. Rare pathogenic mutations within the gene TARDBP that encode TDP-43 were recently reported in ALS but their functional consequences are unknown. To further investigate the pathogenic role of TDP-43 in ALS, a mutation analysis of TARDBP was performed in an Australian cohort of 74 sporadic and 30 familial ALS cases. A novel familial ALS mutation in TDP-43 was identified that substitutes a highly conserved residue (G294V) and is predicted to disrupt the glycine rich domain in the C terminus, a region that plays a role in RNA binding and is required for the exon skipping activity of TDP-43.

Vitamin C-induced decomposition of lipid hydroperoxides to endogenous genotoxins.

Epidemiological data suggest that dietary antioxidants play a protective role against cancer. This has led to the proposal that dietary supplementation with antioxidants such as vitamin C (vit C) may be useful in disease prevention. However, vit C has proved to be ineffective in cancer chemoprevention studies. In addition, concerns have been raised over potentially deleterious transition metal ion-mediated pro-oxidant effects. We have now determined that vit C induces lipid hydroperoxide decomposition to the DNA-reactive bifunctional electrophiles 4-oxo-2-nonenal, 4,5-epoxy-2(E)-decenal, and 4-hydroxy-2-nonenal. The compound 4,5-Epoxy-2(E)-decenal is a precursor of etheno-2'-deoxyadenosine, a highly mutagenic lesion found in human DNA. Vitamin C-mediated formation of genotoxins from lipid hydroperoxides in the absence of transition metal ions could help explain its lack of efficacy as a cancer chemoprevention agent.

Luminescence and thermoluminescence induced by bombardment with protons of 159 million electron volts.

We have observed a red luminescence, qualitatively similar to that of enstatite achondrites, in unsorted fines, their separated mineral phases, and rock chips. The energy efficiency of the plagioclase fraction is approximately 1 percent. At -196 degrees C the effect is enhanced by a factor between 1 and 2. All fractions except ilmenite exhibit blue thermoluminescence with a glow peak near -135 degrees C and an energy efficiency approximately 4 x 10(-6). Unlike the thermoluminescence of terrestrial and meteoritic material, it is nonrepeatable even after annealing at 200 degrees C. Similar thermoluminescence is seen in rock chips, but in unsorted fines it is masked by the opaque fractions.

Detection of endogenous malondialdehyde-deoxyguanosine adducts in human liver.

Endogenous DNA adducts may contribute to the etiology of human genetic disease and cancer. One potential source of endogenous DNA adducts is lipid peroxidation, which generates mutagenic carbonyl compounds such as malondialdehyde. A sensitive mass spectrometric method permitted detection and quantitation of the major malondialdehyde-DNA adduct, a pyrimidopurinone derived from deoxyguanosine. DNA from disease-free human liver was found to contain 5400 adducts per cell, a frequency comparable to that of adducts formed by exogenous carcinogens.

The survival of Salmonella enterica serovar Typhimurium DT104 and total viable counts on beef surfaces at different relative humidities and temperatures.

AIMS: The aim of this study was to investigate changes in Salmonella and total viable count (TVC) survival on beef carcass surfaces stored for 72 h under different combinations of relative humidity (i.e. RH 75% or 96%) and temperature (5 degrees C or 10 degrees C). METHODS AND RESULTS: The influence of low water activity (a(w)) and temperature on the survival and growth of Salmonella enterica serovar Typhimurium DT104 and the aerobic mesophilic flora on meat pieces from different sites on beef carcasses was investigated, under controlled conditions (75% or 96% RH; 5 or 10 degrees C) in an environmental cabinet. Salmonella counts declined during storage at low a(w) (75% RH) conditions at 5 degrees C or 10 degrees C. Salmonella counts increased during storage at high a(w) (96% RH) at 10 degrees C only. At 5 degrees C, TVCs increased during storage at high a(w), but not at low a(w). TVCs increased on all samples from carcasses stored at high or low a(w) at 10 degrees C, except those samples taken from areas of surface fat. CONCLUSIONS: This suggests that substrate composition dictates growth rates under low a(w) conditions. The results are discussed in terms of the possible protective effects of substrate osmolyte accumulation in bacterial survival and/or growth. SIGNIFICANCE AND IMPACT OF THE STUDY: The data obtained in this study provides useful insights on the influence of a(w) and temperature on pathogen survival on meat surfaces at chill temperature.

Prevalence and factors associated with infectious intestinal diseases in Ras Al Khaimah, United Arab Emirates, 2017: A population-based cross-sectional study.

BACKGROUND: The United Arab Emirates (UAE) is a rapidly developing high-income country that has experienced significant population growth, urbanization, and improvements in the standard of living since its formation in 1971. Published estimates on the prevalence of infectious intestinal diseases (IID) in the UAE are scarce and exclusively based on hospital data. The aim of this study was to provide the first prevalence estimates of IID in the UAE. METHODS: A population-based cross-sectional study design using a telephone-based questionnaire was used to estimate the IID prevalence in the previous 4 weeks in a representative sample of the Ras Al Khaimah (RAK) population from January to September 2017. RESULTS: Data were collected from 1254 participants (57.3% male; 25.2% <18 years). The prevalence of IID was 4.2% in the 4 weeks prior to the interview. Multivariate logistic regression analysis identified that being female (odds ratio (OR) 2.4, 95% confidence interval (CI) 1.2-5.1) and having a middle-range monthly household income (approx. USD 4080-<6800: OR 5.42, 95% CI 1.15-25.48; approx. USD 6800-<9530: OR 7.13, 95% CI 1.47-34.57) were positively associated with IID. Age ≥6 years was negatively associated with IID (OR 0.95, 95% CI 0.90-0.99). Forty-nine percent of participants with an IID sought medical care and 20.8% took over-the-counter medication. CONCLUSIONS: This study provides the first population-based prevalence estimates of IID in the UAE, which are similar to those reported in China (4%), but lower than those reported in Canada (10%), the Netherlands (7%), and the USA (6%).

Predominant functional roles for thromboxane A2 and prostaglandin E2 during late nephrotoxic serum glomerulonephritis in the rat.

While much is known regarding acute nephrotoxic serum (NTS)-induced glomerular injury, the glomerular dynamics and pathophysiologic mediators of the more relevant chronic autologous phase remain poorly defined. Studies were performed in rats 14 d after injection of rabbit serum (n = 6), NTS in the absence (n = 6), or presence, of a cyclooxygenase inhibitor, ibuprofen (n = 6) or a thromboxane A2 (TxA2) receptor antagonist, L-670,596 (n = 5). A mesangial macrophage/monocyte infiltrate was noted with equal intensity in all NTS-treated rats. Glomerular generation rates of prostaglandin (PG) E2, PGF2a, and TxA2 in nephritic kidneys were dramatically increased as compared to controls. 2 wk after NTS, there was an increase in glomerular plasma flow rate (SNPF), attainment of filtration pressure disequilibrium, and augmentation of net transcapillary hydraulic pressure difference (delta P). Glomerular filtration rate (GFR), however, was reduced, due to a marked fall in the glomerular capillary ultrafiltration coefficient (Kf). Cyclooxygenase inhibition resulted in normalization of glomerular eicosanoid generation rates, amelioration of proteinuria, afferent vasoconstriction, and normalization of SNPF, delta P, Kf, and GFR. Selective antagonism of TxA2 also led to preservation of Kf, but was without effect on SNPF, thereby leading to elevated values for GFR. Thus, in contrast to the pathophysiologic role of arachidonate-lipoxygenase products in the early heterologous phase, PG-mediated vasodilatation and TxA2-induced reductions in Kf and GFR underlie glomerular functional changes during autologous mesangioproliferative glomerulonephritis.

Estimated rate of thromboxane secretion into the circulation of normal humans.

We have measured the excretion of a major urinary metabolite of thromboxane B2 (TxB2), i.e., 2,3-dinor-TxB2, during the infusion of exogenous TxB2 over a 50-fold dose range to enable estimation of the rate entry of endogenous TxB2 into the bloodstream. Four healthy male volunteers received 6-h i.v. infusions of venhicle alone and TxB2 at 0.1, 1.0, and 5.0 ng/kg X min in random order. They were pretreated with aspirin at a dose of 325 mg/d in order to suppress endogenous TxB2 production. Urinary 2,3-dinor-TxB2 was measured before, during, and up to 24 h after the infusions and in aspirin-free periods, by means of radioimmunoassay. The nature of the extracted immunoreactivity was characterized by thin-layer chromatography and confirmed by negative ion-chemical ionization gas chromatography/mass spectrometry. Aspirin treatment suppressed urinary 2,3-dinor-TxB2 excretion by 80%. The fractional elimination of 2,3-dinor-TxB2 was independent of the rate of TxB2 infusion and averaged 5.3 +/- 0.8%. Interpolation of metabolite values obtained in aspirin-free periods onto the linear relationship between the quantities of infused TxB2 and the amount of metabolite excreted in excess of control values (y = 0.0066x, r = 0.975, P less than 0.001) permitted calculation of the mean rate of entry of endogenous TxB2 into the circulation as 0.11 ng/kg X min. The rate of disappearance of immunoreactive TxB2 from the circulation was monoexponential over the first 10 min with an apparent half-life of 7 min. This corresponded to a maximal estimate of the plasma concentration of endogenous TxB2 of 2.0 pg/ml. These results suggest that ex vivo platelet activation and/or analytical problems confound estimates of endogenous thromboxane release based on plasma TxB2 and provide a rationale for seeking longer-lived enzymatic metabolites of TxB2 in plasma.

Survival of antibiotic resistant and antibiotic sensitive strains of E. coli O157 and E. coli O26 in food matrices.

Escherichia coli O157:H7 or E. coli O26, which were AS (antibiotic sensitive), AR (laboratory created antibiotic resistant mutants), or naturally MAR (multi-antibiotic resistant), were inoculated into laboratory media, yoghurt or orange juice and their growth/survival monitored during enrichment at 37 degrees C or storage at 4 degrees C. The strains were also inoculated into minced beef and their thermal inactivation (D-values) examined at 55 degrees C, with and without a prior heat shock at 48 degrees C. The growth kinetics (lag phases, growth rates) of the VTEC (verocytotoxigenic E. coli), incubated over 24 h at 37 degrees C in laboratory media, were similar regardless of the presence or absence of antibiotic resistance. In yoghurt and orange juice, E. coli O157:H7 MAR died off significantly faster (P<0.05) than any of other VTEC strains examined. E. coli O157:H7 MAR was also found to be significantly more heat sensitive (P<0.05) than the other VTEC strains tested. The reasons for the observed differences in survival of the different VTEC strains and the link between antibiotic resistance and survival in VTEC organisms are discussed.

Antimicrobial resistance in Irish isolates of verocytotoxigenic Escherichia coli (E. coli)--VTEC.

This study compared the antimicrobial resistance profiles of Escherichia coli O157:H7 isolates (n=257) recovered from bovine hides, minced beef and human clinical samples in Ireland, to those profiles of a range of Irish non-O157 E. coli (O111 and O26) isolates (n=31) from a variety of clinical and veterinary sources. Four multi-drug resistant (MDR) E. coli O157:H7 food isolates were identified, with resistance to 10 (1 isolate), 6 (1 isolate) and 4 (2 isolates) antimicrobial agents, respectively. Two of these isolates (resistant to 7 and 4 antimicrobial classes) were characterised further by molecular methods and found to contain class 1 integrons along with a beta-lactamase-encoding tem-1 gene. Transfer of antimicrobial resistance (ampicillin, streptomycin and sulphonamides), the tem-1 gene and markers (int1, qacEDelta1, sul1) characteristic of class 1 integrons were evident in one MDR isolate (resistant to 4 antimicrobial classes) when conjugation and transformation experiments were performed. A clinical isolate and a veterinary isolate of the O111 serotype were MDR and resistant to 4 and 3 antimicrobial classes, respectively. These data suggest that the prevalence of antimicrobial resistance among the three VTEC serotypes examined in this study is low. However, these organisms may become a public health risk should they enter the food chain.

Tumor cell-derived 12(S)-hydroxyeicosatetraenoic acid induces microvascular endothelial cell retraction.

Our previous work demonstrated that the 12-lipoxygenase metabolite of arachidonic acid, 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE] induced a nondestructive and reversible retraction of cultured endothelial cells. In the current study we tested the hypothesis that tumor cells produce 12(S)-HETE during their interactions with endothelial cells which in turn induces endothelial cell retraction. Coincubation of Lewis lung carcinoma cells or elutriated B16 amelanotic melanoma (B16a) cells but not 3T3 fibroblasts with microvascular endothelial cells (CD3) resulted in a time- and concentration-dependent retraction of the CD3 monolayers as revealed by quantitative binding assays and phase contrast microscopy. Lewis lung carcinoma cell-induced endothelial cell retraction was blocked by specific lipoxygenase inhibitors but not by cyclooxygenase inhibitors, suggesting the involvement of a lipoxygenase metabolite(s). Radioimmunoassay and high-performance liquid chromatography analysis of tumor cell extracts identified 12(S)-HETE as the major lipoxygenase metabolite of arachidonic acid and tumor cell generation of 12(S)-HETE was specifically blocked by a select 12-lipoxygenase inhibitor N-benzyl-N-hydroxy-5-phenyl-pentamide. The identity and stereochemistry of tumor cell-derived 12-HETE was substantiated by gas chromatography-mass spectrometry analysis and chiral phase high-performance liquid chromatography, respectively. Lewis lung carcinoma cell adhesion to CD3 monolayers was accompanied by an enhanced 12(S)-HETE biosynthesis by tumor cells, which paralleled the tumor cell-induced endothelial cell retraction in a cell number-dependent manner. Pretreatment of tumor cells with N-benzyl-N-hydroxy-5-phenylpentamide inhibited both increased 12(S)-HETE biosynthesis and tumor cell-induced endothelial cell retraction. Highly metastatic variants of elutriated B16a cells which had been shown to produce large quantities of 12(S)-HETE induced significant CD3 cell retraction, while low metastatic subpopulations of B16a cells which synthesized no or little 12(S)-HETE did not induce endothelial cell retraction. These results suggest that 12(S)-HETE synthesis during tumor cell-endothelial cell interactions may represent a key contributory factor in cancer metastasis.

Metabolism of 12(R)-hydroxyeicosatetraenoic acid by rat liver microsomes.

The in vitro metabolism of 12(R)-hydroxyeicosatetraenoic acid was studied using freshly isolated rat liver microsomes. Ten metabolites were isolated and identified by a combination of ultraviolet spectroscopy and gas chromatography/mass spectrometry. The two major metabolites were dihydroxyeicosatetraenoic acids generated by omega/omega-1 hydroxylation. Oxidation at C-5 resulted in the formation of four leukotriene-like compounds, two of which differed from leukotriene B4 in double-bond geometry alone. The other two differed from leukotriene B4 in olefin geometry and C-5 configuration. Epoxidation at the 14,15-olefin resulted in the formation of two diastereomeric epoxy alcohols, while C-16 hydroxylation gave two diastereomeric dihydroxyeicosatetraenoic acids.

Incorporation of 12(S)-hydroxyeicosatetraenoic acid into the phosphatidylcholine signaling pathway.

The incorporation of 12-lipoxygenase metabolites into phospholipids (PLs) could modify second messengers such as diacylglycerols (DAG) and phosphatidic acids. Incubation of [(14)C]12(S)-HETE (1 microM) with bovine pulmonary artery endothelial cells (BPAEC), resulted in its incorporation in PLs with concentration-dependent kinetics. After a 4 h incubation, the proportion of radioactive phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) + phosphatidylinositol (PI) isolated by TLC, was 77.9%, 16.4% and 5.7%, respectively. In PC, [(14)C]12(S)-HETE was incorporated at the position 2 of the glycerol. Three major peaks of radioactive PC were isolated on RP-HPLC which were hydrolysed by phospholipase C (PLC). The resulting diacylglycerols were derivatized and identified by GC/MS as 1-oleyl-, 1-stearoyl- and 1-palmitoyl-2-[12-HETE] PC. BPAEC were incubated with [(14)C]12(S)-HETE (1 microM) before stimulation with bradykinin (1 microM). (A) 1-acyl-2-[12-HETE] diacylglycerols were isolated, derivatized and analysed by MS. We identified a major ion with m/z = 926 that corresponds to the molecular ion of authentic 1-stearoyl-2-12(S)-HETE DAG, and 2 other ions with m/z = 924 and 898 that correspond to the molecular ions of 1-oleyl- and 1-palmitoyl-2-12(S)-HETE DAG, respectively. (B) Radioactive PA was isolated and hydrolysed by alkaline phosphatase. The MS of resulting diacylglycerols identified 1-stearoyl-, 1-oleyl-, and 1-palmitoyl-2-12(S)-HETE phosphatidic acids. The quantities of 12-HETE PA and the 3 major 12-HETE diacylglycerols were shown to increase following bradykinin stimulation. Thus, the incorporation of 12(S)-HETE into PLs results in the production of altered phosphatidic acids and diacylglycerols. The time-course of increases in 1-acyl-2-(12-HETE) phosphatidic acids and 1-acyl-2-(12-HETE) diacylglycerols showed maximal concentrations 1 and 2 min after bradykinin stimulation, respectively, followed by the decrease of both compounds. Propranolol, an inhibitor of PA phosphohydrolase, totally abolished the bradykinin-induced increase in 12-HETE DAG while increasing the magnitude and duration of 12-HETE PA release. The inhibiting effect of propranolol on bradykinin-induced increase of 12-HETE DAG demonstrates that 12-HETE PA is the principal precursor for 12-HETE DAG. This affords a novel method for confirming the major role of phospholipase D in PC metabolic pathways triggered during cell signaling.

Thromboxane B2 uptake and metabolism in isolated perfused lung. Identification and comparison with prostaglandin F2 alpha.

Thromboxane B2 was metabolised in isolated perfused guinea-pig lungs to a product identified by negative ion chemical ionisation mass spectrometry as 13,14-dihydro-15-ketothromboxane B2. Conversion was measured by radio TLC and was greater in guinea-pig than rat lungs (29.1 vs. 13.8% at 10 ng/ml), but similar in lungs from normal and sensitized guinea-pigs. Thromboxane B2 metabolism was less than that of prostaglandin F2 alpha but, like it, was prevented at 5 degrees C and reduced by cycloheximide pretreatment. Tissue to medium ratio in perfused guinea-pig lungs was 3.4 for thromboxane B2, but 0.2 for insulin (showing that thromboxane B2 is accumulated within the lung) and was altered after experimental manipulations. Neither lung slices, crude homogenates, cytosolic and microsomal fractions nor purified prostaglandin 15-hydroxydehydrogenase metabolised thromboxane B2 in vitro, although prostaglandin F2 alpha was extensively inactivated. Quantitative partition coefficient and albumin-binding data confirm that thromboxane B2 lacks prominent lipophilicity, implying that cellular uptake in lung must be carrier-mediated. We conclude that thromboxane B2 is a substrate for pulmonary degradation which may form a route for the biological inactivation of thromboxane A2. Its resistance to prostaglandin 15-hydroxydehydrogenase as conventionally tested remains paradoxical and is discussed.

Characterisation of E. coli O157 isolates from bovine hide and beef trimming in Irish abattoirs by pulsed field gel electrophoresis.

Escherichia coli O157 isolates from bovine hide (n=117) and beef trimmings (n=32) from a single abattoir were examined by pulsed field gel electrophoresis (PFGE). Using BioNumerics software, dendrograms of isolates from each sample type (i.e. hide and beef trimming) were produced. In assessing the genetic relatedness of isolates, a similarity criterion of 80% was applied. The 117 E. coli O157 hide isolates were grouped into 14 clusters, comprising of 109 different PFGE profiles. Of the 109 different PFGE profiles, 8 were common to multiple isolates (i.e. shared 100% similarity by PFGE). The 32 E. coli O157 beef trimming isolates produced 28 different PFGE profiles and 2 clusters. Of the 28 PFGE profiles, 2 were common to multiple isolates and the remaining 26 were distinct. On a number of sampling occasions, isolates displaying identical PFGE patterns were recovered from multiple isolates collected from a single sample type (i.e. hides or trimmings), suggesting cross contamination from contaminated hides/animals to uncontaminated hides/animals and from contaminated beef trimmings to uncontaminated beef trimmings during abattoir operations.