Risk factors for Escherichia coli O157 shedding and super-shedding by dairy heifers at pasture.

We undertook a longitudinal study within a cohort of 52 dairy heifers maintained under constant management systems and sampled weekly to investigate a comprehensive range of risk factors which may influence shedding or super-shedding of E. coli O157 (detected by direct faecal culture and immunomagnetic separation). E. coli O157 was detected from 416/933 (44.6%) samples (faeces and recto-anal mucosal swabs) and 32 (3.4%) samples enumerated at >10000 c.f.u./g. Weekly point prevalence ranged from 9.4% to 94.3%. Higher temperature (P < 0.001), rainfall (P = 0.02), relative humidity (P < 0.001), pasture growth (P = 0.013) and body score (P = 0.029) were positively associated with increased shedding. Higher rainfall (P < 0.001), hide contamination (P = 0.002) and increased faecal consistency (P = 0.023) were positively associated with super-shedding. Increased solar exposure had a negative effect on both shedding and super-shedding within bivariate analyses but in the final multivariate model for shedding demonstrated a positive effect (P = 0.017). Results suggest that environmental factors are important in E. coli O157 shedding in cattle.

Design of a simplified histopathologic model for gastrointestinal inflammation in dogs.

Significant interobserver variability in the diagnostic interpretation of endoscopic gastrointestinal (GI) specimens exists even with the use of World Small Animal Veterinary Association (WSAVA) standardization criteria. Chi-square analyses compared the extent of pathologists' agreement for microarchitectural features of inflammation in endoscopic specimens obtained from 253 animals of the original WSAVA study. Patterns of agreement between pathologists were classified as broad (3/4 pathologists agreed), dichotomous (2/4 pathologists agreed), or divergent (no agreement between pathologists). The simplified model for GI inflammation was based on those parameters for which the pathologists had either broad or minimally divergent opinions of histopathologic significance. In this model, the parameters chosen were as follows: gastric parameters (intraepithelial lymphocytes [IELs], lamina propria [LP] infiltrates, and mucosal fibrosis), duodenal parameters (villus atrophy, epithelial injury, IELs, crypt changes, and LP infiltrates), and colonic parameters (epithelial injury, crypt dilation, fibrosis, LP infiltrates, and goblet cell depletion). Preliminary data using this simplified model showed excellent correlation between pathologists in defining the presence and extent of GI inflammation in dogs.

Comparison of histopathologic findings in biopsies from the duodenum and ileum of dogs with enteropathy.

BACKGROUND: In the investigations of dogs with chronic small intestinal diarrhea collection of ileal biopsies lengthens procedural time and has been of uncertain value. OBJECTIVES: To evaluate whether there was agreement between histologic changes present in samples of duodenal and ileal mucosa, and hence to provide initial information in the process of determining whether collection of ileal biopsies is clinically justified. ANIMALS: 40 dogs with chronic small and large intestinal diarrhea from which endoscopic (in 30 cases) or surgical (in 10 cases) duodenal and ileal biopsies had been collected. METHODS: Samples were reviewed concurrently by two observers (MJD and MDW) using the scoring system developed by the World Small Animal Veterinary Association (WSAVA) Gastrointestinal Standardization Group. Comparisons were made by kappa analysis. RESULTS: Microscopic pathology was observed in 30 cases. Only eight out of this 30 (27%) had the same histopathologic diagnosis in both the duodenum and the ileum. This dropped to 3 out of 30 (10%) if different disease severity was also considered as disagreement. Microscopic pathology would have been found in 60% and 80% of the 30 cases, if only duodenal or ileal biopsies respectively, had been available. CONCLUSIONS AND CLINICAL IMPORTANCE: There was poor agreement between histopathological findings from duodenal versus ileal biopsies with abnormalities sometimes being more readily detected in the ileum. Routine collection of ileal plus duodenal samples appears warranted when concurrent small and large intestinal diarrhea is present.

Effect of tissue processing on assessment of endoscopic intestinal biopsies in dogs and cats.

BACKGROUND: Prior studies failed to detect significant association between hypoalbuminemia and small intestinal lesions. HYPOTHESIS: Use of pictorial templates will enhance consistency of interpathologist interpretation and identification of intestinal lesions associated with hypoalbuminemia. ANIMALS: Tissues from 62 dogs and 25 cats examined as clinical cases at 7 referral veterinary practices in 4 countries. METHODS: Retrospective, observational study. Histopathology slides from sequential cases undergoing endoscopic biopsy were examined by 4 pathologists by pictorial templates. Changes for 9 microscopic features were recorded as normal, mild, moderate or severe, and 2- and 4-point scales were tested for consistency of interpretation. Logistic regression models determined odds ratios (OR) of histologic lesions being associated with hypoalbuminemia while kappa statistics determined agreement between pathologists on histologic lesions. RESULTS: There was poor agreement (kappa = -0.013 to 0.3) between pathologists, and institution of origin of slides had effect (kappa = 1.0 for 3 of 4 lesions on slides from Institution 5) on agreement between pathologists on selected histologic features. Using 2 point as opposed to 4-point grading scale increased agreement between pathologists (maximum kappa = 0.69 using 4-point scale versus maximum kappa = 1.0 using 2-point scale). Significant association (P = .019- .04; 95% OR = 3.14-10.84) between lacteal dilation and hypoalbuminemia was found by 3 pathologists. CONCLUSIONS AND CLINICAL IMPORTANCE: Substantial inconsistency between pathologists remains despite use of pictorial template because of differences in slide processing. Distinguishing between mild and moderate lesions might be important source of the disagreement among pathologists.

RADIOSENSITIVITY TO HIGH ENERGY IRON IONS IS INFLUENCED BY HETEROZYGOSITY for ATM, RAD9 and BRCA1.

Loss of function of DNA repair genes has been implicated in the development of many types of cancer. In the last several years, heterozygosity leading to haploinsufficiency for proteins involved in DNA repair was shown to play a role in genomic instability and carcinogenesis after DNA damage is induced, for example by ionizing radiation. Since the effect of heterozygosity for one gene is relatively small, we hypothesize that predisposition to cancer could be a result of the additive effect of heterozygosity for two or more genes critical to pathways that control DNA damage signaling, repair or apoptosis. We investigated the role of heterozygosity for Atm, Rad9 and Brca1 on cell oncogenic transformation and cell survival induced by 1GeV/n 56Fe ions. Our results show that cells heterozygous for both Atm and Rad9 or Atm and Brca1 have high survival rates and are more sensitive to transformation by high energy Iron ions when compared with wild-type controls or cells haploinsufficient for only one of these proteins. Since mutations or polymorphisms for similar genes exist in a small percentage of the human population, we have identified a radiosensitive sub-population. This finding has several implications. First, the existence of a radiosensitive sub-population may distort the shape of the dose-response relationship. Second, it would not be ethical to put exceptionally radiosensitive individuals into a setting where they may potentially be exposed to substantial doses of radiation.

The use of plain abdominal x rays in the emergency department.

Abdominal x rays expose patients to significant doses of radiation and have limited use in emergency medicine. This review explores the evidence supporting the use of abdominal x rays in the emergency department, with particular reference to recent guidelines published by the Royal College of Radiologists. The authors' recommendations for the use of abdominal x rays in the emergency department are given.

Histopathological standards for the diagnosis of gastrointestinal inflammation in endoscopic biopsy samples from the dog and cat: a report from the World Small Animal Veterinary Association Gastrointestinal Standardization Group.

The characterization of inflammatory change in endoscopic biopsy samples of the gastrointestinal mucosa is an increasingly important component in the diagnosis and management of canine and feline gastrointestinal disease. Interpretation has hitherto been limited by the lack of standard criteria that define morphological and inflammatory features, and the absence of such standardization has made it difficult, if not impossible, to compare results of retrospective or prospective studies. The World Small Animal Veterinary Association (WSAVA) Gastrointestinal Standardization Group was established, in part, to develop endoscopic and microscopical standards in small animal gastroenterology. This monograph presents a standardized pictorial and textual template of the major histopathological changes that occur in inflammatory disease of the canine and feline gastric body, gastric antrum, duodenum and colon. Additionally, a series of standard histopathological reporting forms is proposed, to encourage evaluation of biopsy samples in a systematic fashion. The Standardization Group believes that the international acceptance of these standard templates will advance the study of gastrointestinal disease in individual small companion animals as well as investigations that compare populations of animals.

Effect of sample quality on the sensitivity of endoscopic biopsy for detecting gastric and duodenal lesions in dogs and cats.

BACKGROUND: The quality of histopathology slides of endoscopic biopsies from different laboratories varies, but the effect of biopsy quality on outcome is unknown. HYPOTHESIS: The ability to demonstrate a histologic lesion in the stomach or duodenum of a dog or cat is affected by the quality of endoscopic biopsy samples submitted. More endoscopic samples are needed to find a lesion in poor-quality tissue specimens. ANIMALS: Tissues from 99 dogs and 51 cats were examined as clinical cases at 8 veterinary institutions or practices in 5 countries. METHODS: Histopathology slides from sequential cases that underwent endoscopic biopsy were submitted by participating institutions. Quality of the histologic section of tissue (inadequate, marginal, adequate), type of lesion (lymphangiectasia, crypt lesion, villus blunting, cellular infiltrate), and severity of lesion (normal, mild, moderate, severe) were determined. Sensitivity of different quality tissue samples for finding different lesions was determined. RESULTS: Fewer samples were required from dogs for diagnosis as the quality of the sample improved from inadequate to marginal to adequate. Duodenal lesions in cats displayed the same trend except for moderate duodenal infiltrates for which quality of tissue sample made no difference. Gastric lesions in dogs and mild gastric lesions in cats had the same trend, whereas the number of tissue samples needed to diagnose moderately severe gastric lesions in cats was not affected by the quality of tissue sample. CONCLUSIONS AND CLINICAL IMPORTANCE: The quality of endoscopically obtained tissue samples has a profound effect on their sensitivity for identifying certain lesions, and there are differences between biopsies of canine and feline tissues.

Why did severe feather pecking and cannibalism outbreaks occur? An unintended case study while investigating the effects of forage and stress on pullets during rearing.

This 2 × 2 factorial experiment aimed to investigate the effects of stimulating foraging behavior from wk 6 and imposed stress at wk 16 on the development of severe feather pecking (SFP) in chickens reared for free-range egg production. Non-beak-trimmed ISA Brown chicks were purchased at one day old and floor-reared on wood shavings. From wk 6, straw was provided daily in dispensers (Forage vs. No forage) to stimulate foraging. At wk 15, there were 16 pens of 50 pullets. "Stressors" were applied to half the pens in wk 16 via combined transport, relocation, and mixing (TRM) of pullets, simulating activities around transfer from the rearing to egg-laying farm (TRM vs. Not TRM). Range access was permitted from wk 21. Behavior, plumage damage (PD), growth, egg production, feed use, injuries, and mortalities were recorded, along with litter moisture and pH. In wk 26, an SFP outbreak commenced. By wk 34, PD was worse in south- than north-aspect pens (P < 0.001). Further, PD was more affected by side of the shed than the experimental treatments. In wk 30, an outbreak of injurious pecking (IP) commenced in the 4 TRM-treatment pens on the south side, with IP deaths almost 3 times more common in the Forage+TRM than No forage+TRM treatment. We suggest factors associated with a 13-day rainfall event that occurred in late winter predisposed the flock to SFP. While multiple factors such as winter cold, muddy ranges, damp floor litter with elevated pH, among others coincided, hens were clearly more impacted in south- than north-aspect pens. Once initiated, SFP possibly spread via social learning, and by wk 40, ∼98% of hens had PD. Interestingly, the IP outbreak was related to a combination of factors (stressors?), such as being housed in colder, damper south-aspect pens (note: southern hemisphere), having added Forage, and TRM. These unexpected relationships could help direct future research to identify the specific factors involved in the causation of SFP and IP/cannibalism outbreaks.

Whole-Blood Taurine Concentrations in Cats With Intestinal Disease.

BACKGROUND: Increased delivery of taurine-conjugated bile acids to the distal bowel can lead to dysbiosis resulting in colitis in mouse models of inflammatory bowel disease. A similar situation also could occur in cats with intestinal disease and might therefore result in decreased whole-body taurine concentration. HYPOTHESIS/OBJECTIVES: To determine whether whole-blood taurine concentrations are decreased at the time of diagnosis in cats with intestinal disease and to correlate concentrations with clinical and laboratory variables. ANIMALS: Twenty-one cats with chronic inflammatory enteropathy and 7 cats with intestinal neoplasia from the University of Bristol. METHODS: Cats that had undergone a thorough investigation consisting of a CBC, serum biochemistry, serum cobalamin and folate concentrations, transabdominal ultrasound examination and histopathology of intestinal biopsy specimens, as well as additional testing if indicated, were included. Whole-blood from these cats collected at the time of histologic diagnosis and stored in ethylenediaminetetraacetic acid was retrospectively analyzed for taurine with an automated high-performance liquid chromatography amino acid analyzer. RESULTS: Although whole-blood taurine concentrations remained within the reference range, those cats with predominantly large intestinal clinical signs had significantly lower concentrations than did cats with small intestinal and mixed bowel clinical signs (P = 0.033) and this difference also was significant when assessed only in cats with chronic inflammatory enteropathy (P = 0.019). CONCLUSIONS AND CLINICAL IMPORTANCE: Additional studies are needed to determine whether large intestinal signs in cats with chronic inflammatory enteropathy are caused by alterations in the microbiota arising as a consequence of increased delivery of taurine-conjugated bile acids.

The impact of gender and age on the nutritional parameters of alpaca (Vicugna pacos) meat, colour stability and fat traits.

Meat quality parameters for 50 huacaya alpacas, representing three age groups (18, 24 and 36months) and two genders (females and castrated males) were studied. Prior to chilling, samples of m. longissimus thoracis et lumborum (LL) were taken to determine isocitrate dehydrogenase activity and glycogen concentration, and further meat quality samples were taken after 24h. Alpaca meat has low levels (<1%) of intramuscular fat in the LL, m. semimembranosus and m. biceps femoris, but the level in the LL increases with animal age, with levels of desirable polyunsaturated fatty acids (PUFA) ranging from 96.3 to 136.4mg/100g. Lipid oxidisation post retail display ranged from 1.27 to 1.96MDA/kg meat. Colour stability testing indicated alpaca meat was relatively stable during retail display with day of display having no significant effect on lightness (L*), or the 630nm/580nm ratio. These results may relate to the high proportion (76%) of glycolytic and type IIX muscle fibres in LL.

The inaugural Frank Ellis Lecture--latrogenic cancer: the impact of intensity-modulated radiotherapy.

It is an honour and personal pleasure to give the inaugural Frank Ellis Lecture to celebrate his 100th birthday, and to acknowledge his enormous contributions to radiation oncology. Intensity-modulated radiotherapy (IMRT) allows dose to be concentrated in the tumour volume while sparing normal tissues. However, the downside to IMRT is the potential to increase the number of radiation-induced second cancers because more fields are used which involves a bigger volume of normal tissue exposed to lower doses. It has been estimated that IMRT may double the incidence of solid cancers in long-term survivors. This may be acceptable in older patients if balanced by an improvement in local tumour control and reduced toxicity. On the other hand, the incidence of second cancers is higher in children, so that doubling it may not be acceptable. IMRT represents a special case for children. First, they are more sensitive to radiation-induced cancer than adults. Second, radiation scattered from the treatment volume is more important in the small body of the child. Third, there is the question of genetic susceptibility, as many childhood cancers involve a germline mutation. The levels of leakage radiation in current Linacs can be reduced, but the cost would be substantial. An alternative strategy is to replace X-rays with protons. This is an advantage only if the proton machine uses a pencil scanning beam, as passive modulation of a scattering foil produces neutrons, which results in an effective dose to the patient higher than that characteristic of IMRT.

A microbeam study of DNA double-strand breaks in bystander primary human fibroblasts.

Radiation-induced bystander effect has been well documented. However, the mechanisms are poorly understood. How we incorporate this effect into the classical models of risk assessment remains an open question. Here, the induction of bystander effect was studied by assessing DNA double-strand break (DSB) formation in situ with the rapid and sensitive gamma-H2AX focus formation assay. Utilising the Columbia University single-cell microbeam system to deliver 2 or 20 individual alpha particles to selected cell nuclei in a precisely known proportion of cells in a population, the induced DNA DSB incidences were quantified 30 min and 18 h post-IR. The increase in DNA DSB incidence in bystander cells lacked of a linear dose response indicating that neither the dose of irradiation nor proportion of irradiated cells in a population, is a critical parameter. This study confirms a binary all-or-nothing model of triggering the bystander response. The delay and persistence of the bystander response suggests a different mechanism of DSB induction in bystander cells than in directly irradiated cells.

Bacterial cholangitis/cholangiohepatitis with or without concurrent cholecystitis in four dogs.

OBJECTIVES: To evaluate the clinical, clinical pathology, diagnostic imaging, microbiological and pathological features of cholangitis/cholangiohepatitis in the dog. METHODS: The study design was a retrospective review of cases of bacterial cholangitis/cholangiohepatitis presented to the University of Bristol during the period 1995 to 2000. The diagnosis was made based on hepatic histopathological findings and positive bile culture results. RESULTS: Four dogs met the inclusion criteria. Common presenting signs included anorexia (n=4), jaundice (n=4), vomiting (n=4) and pyrexia (n=2). All four dogs had a leucocytosis or neutrophilia reported at some time in their history along with serum bilirubin elevation. In addition, serum alkaline phosphatase and alanine transaminase activity was increased in all of the dogs in which it was measured both before and at the time of referral. In general, the diagnostic imaging findings were non-specific. Organisms cultured from bile aspirates were Escherichia coli (n=3), Clostridium species (n=2) and a faecal Streptococcus species (n=1). Two cases resolved with medical treatment alone; two with concurrent cholecystitis required cholecystectomy. Following surgery, both of these cases showed a resolution of clinical signs. CLINICAL SIGNIFICANCE: This report highlights the fact that bacterial cholangitis/cholangiohepatitis with or without concurrent cholecystitis should be considered as a potential differential in dogs presenting with signs referable to biliary tract disease.

Biological effects of heat.

The biological effects of heat appear to be favorable for its use to treat cancer. Heat kills cells in a predictable and repeatable way. The age response function complements X-rays in that S-phase cells are most sensitive, and at the same time cells that are at low pH or are nutritionally deprived are also more sensitive. This offers the possibility that cycling tumor cells and quiescent cells that have respired to hypoxia may be more sensitive to heat than are the slowly turning over cells of the normal tissues responsible for late effects. Thermotolerance, in general, represents a problem and a complication in clinical practice but may be exploited to advantage. The interaction of heat with ionizing radiation has been studied extensively and is complex; in general, heat inhibits the repair of both sublethal and potentially lethal X-ray damage, but it is not obvious how to exploit this to advantage. By contrast, the potentiation by heat of the action of chemotherapy agents has been relatively neglected. This is a promising area, since local hyperthermia can "target" drug action in a way not otherwise possible. Heat is a weak mutagen and has not been shown to be a carcinogen; this is a most desirable property at a time of increasing concern for the oncogenic potential of agents used to treat cancer.

Taxol, radiation, and oncogenic transformation.

The novel antineoplastic drug taxol has been shown to be active clinically against several types of human tumors. With improvement in treatment strategy and the number of long-term survivors increasing, a question that needs to be addressed is the potential carcinogenic effect of the treatment in the induction of second malignancies. We show here that when tested using an in vitro assay for oncogenic transforming potential, taxol is ineffective in focus induction at doses significantly higher than those used in the clinic. However, taxol enhances the oncogenic potential of gamma-rays in a synergistic fashion. The fact that taxol blocks cells at the G2/M phases of the cell cycle may account for this interaction since G2/M are relatively radiosensitive phases of the cell cycle.

Modest increased sensitivity to radiation oncogenesis in ATM heterozygous versus wild-type mammalian cells.

Subpopulations that are genetically predisposed to radiation-induced cancer could have significant public health consequences. Individuals homozygous for null mutations at the ataxia telangiectasia gene are indeed highly radiosensitive, but their numbers are very small. Ataxia Telangiectasia heterozygotes (1-2% of the population) have been associated with somewhat increased radiosensitivity for some end points, but none directly related to carcinogenesis. Here, intralitter comparisons between wild-type mouse embryo fibroblasts and mouse embryo fibroblasts carrying ataxia telangiectasia mutated (ATM) null mutation indicate that the heterozygous cells are more sensitive to radiation oncogenesis than their normal, litter-matched, counterparts. From these data we suggest that Ataxia Telangiectasia heterozygotes could indeed represent a societally-significant radiosensitive human subpopulation.

Cytological effects of 1-(2-nitro-1-imidazolyl)-3-methoxy-2-propanol (misonidazole) on hypoxic mammalian cells in vitro.

Hypoxic Chinese hamster V-79 cells were examined for light-microscope morphology, progression through the cell cycle, chromosomal aberrations, and viability, after incubation with the 2-nitroimidazole, misonidazole [1-(2-nitro-1-imidazolyl)-3 methoxy-2-propanol]. Cytological examination of cells up to 42 hr after incubation with the drug at 37 degrees indicated that increasing contact time and increasing drug concentrations interfered with cell attachment and progressively slowed cell progression through the cell cycle. Forty-two hr after a 5.5-hr treatment with 5 mM misonidazole, the majority of cells contained heteropyknotic nuclei, whereas less than 3% had progressed into mitosis. Of the few cells that reached mitosis by 42 hr, the level of chromosomal aberrations was 6 times that due to hypoxia alone. However, the majority of metaphases (70%) were unaltered; thus about 2% of the treated cell population passed into mitosis unaltered. After a 5.5-hr incubation with 5 mM misonidazole, 98% of the cells also had lost their ability to produce clones. It is suggested that the cytotoxic effect of this drug on hypoxic cells is that the cytotoxic effect of this drug on hypoxic cells is largely mediated via an interphase cell death, with a minor effect due to chromosome aberrations and cell death from genetic inequality of progeny cells. The ability of misonidazole to kill hypoxic, noncycline cells, which may limit the curability of some tumors with conventional X-rays or chemotherapy agents, makes it of considerable potential interest.

Taxol sensitizes human astrocytoma cells to radiation.

Taxol is a chemotherapeutic drug which acts by stabilizing microtubules, preventing normal mitosis and resulting in a block of the cell cycle at G2 and M. The drug is isolated from the yew, Taxus sp. L., and is currently being evaluated in a series of Phase II and Phase III clinical trials. Taxol blocks cells in the most radiosensitive phases of the cell cycle and thus could act as a cell cycle-specific radiosensitizer. We report the results of combined taxol-radiation exposures in the human Grade III astrocytoma cell line, G18. Taxol is a potent inhibitor of G18 cell division; a concentration of 10 nM is cytostatic for a cell population observed for at least two doubling times. Cell survival curves for G18 cells showed a significant concentration-dependent interaction between taxol and radiation. Treatment of G18 cells with a fixed taxol concentration and radiation dose showed the interaction to be dependent on the duration of taxol exposure and consequently the fraction of cells in the G2 or M phase of the cell cycle. The sensitizer enhancement ratio for 10 nM taxol at 10% survival is 1.8 and, for 1 nM taxol, it is 1.2. These results suggest that appropriate combinations of taxol have a more than additive interaction in human tissue culture and may have a role in clinical protocols.