Inhibition of polymerase chain reaction for the detection of Escherichia coli O157:H7 and Salmonella enterica on walnut kernels.

The aim of this study was to determine whether Escherichia coli O157:H7 can be reliably detected and isolated from walnut kernels using standard methods of analysis. The limit of detection approached 1 cell per analytical unit (25 g) for E. coli O157:H7 on walnut kernels enriched in modified tryptic soy broth with 20 μg/ml novobiocin and plating onto selective agar media.

Evaluation of murine norovirus persistence in environments relevant to food production and processing.

Human norovirus (NoV) causes outbreaks of acute gastroenteritis associated with many ready-to-eat foods, including fresh produce. Effective inactivation procedures must consider virus survival under conditions of produce production and processing. This study aimed to investigate the persistence of NoV in a variety of environments, using murine NoV (MNV) as a surrogate for NoV.

Non-O157 verotoxigenic Escherichia coli and beef: a Canadian perspective.

Verotoxigenic Escherichia coli (VTEC) are important foodborne pathogens in Canada. VTEC of the O157:H7 serogroup have been the focus of regulatory action and surveillance in both Canada and the USA, due to their role in a number of high profile outbreaks. However, there is increasing evidence that other VTEC serogroups cause a substantial proportion of human illness.

Cronobacter spp. (Enterobacter sakazakii): advice, policy and research in Canada.

Although the number of reported cases of Cronobacter infection in Canada is low, Health Canada has been actively studying this organism since 1991. After reviewing the situation at the national level and due to health concerns with powdered formulae and its international trade, in 2003, Health Canada raised this issue at the international level by proposing to revise the Code of Practice for Powdered Formulae for Infants and Young Children at the Codex Alimentarius Committee of Food Hygiene. Canada volunteered to chair the Working Group that would be developing the Code, and the Code was completed in four years.

Evaluation of the BAX gel and fluorometric systems for the detection of foodborne Salmonella.

The present study compared the sensitivity of the BAX automated fluorometric and the recently discontinued BAX gel electrophoresis systems with a standard culture method to detect Salmonella in 333 high-moisture and 171 low-moisture foods. A total of 95 naturally contaminated foods, including 63 high-moisture and 32 low-moisture foods, were detected by the standard culture method. No contaminated samples were identified exclusively by the BAX systems.

Survival of calicivirus in foods and on surfaces: experiments with feline calicivirus as a surrogate for norovirus.

Although there is a large body of evidence incriminating foods as vehicles in the transmission of norovirus, little is known about virus survival in foods and on surfaces. Feline calicivirus was used as a surrogate for norovirus to investigate its survival in representative foods of plant and animal origin and on metal surfaces. Known concentrations of feline calicivirus in a natural fecal suspension were deposited onto lettuce, strawberries, ham, or stainless steel and incubated for 7 days at refrigeration or room temperatures.

Norovirus cross-contamination during food handling and interruption of virus transfer by hand antisepsis: experiments with feline calicivirus as a surrogate.

While there is good epidemiological evidence for foods as vehicles for norovirus transmission, the precise means of spread and its control remain unknown. The feline calicivirus was used as a surrogate for noroviruses to study infectious virus transfer between hands and selected types of foods and environmental surfaces. Assessment of the potential of selected topicals in interrupting such virus transfer was also made.

Present situation in Canada regarding Listeria monocytogenes and ready-to-eat seafood products.

The present situation regarding Listeria monocytogenes and ready-to-eat (RTE) seafood is discussed. An updated regulatory policy on L. monocytogenes directs inspection and compliance action to those RTE foods capable of supporting growth of the organism and is based on a combination of inspection, environmental sampling and product testing.

Rapid concentration and detection of hepatitis A virus from lettuce and strawberries.

Immunomagnetic beads-PCR (IM-PCR), positively-charged virosorb filters (F), or a combination of both methods (F-IM-PCR) were used to capture, concentrate and rapidly detect hepatitis A virus (HAV) in samples of lettuce and strawberries experimentally contaminated. Direct reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of the collected HAV-beads complex showed a detection limit of 0.5 plaque forming units (PFU) of the virus present in 1-ml of wash solution from the produce, which was several hundred-fold more sensitive than that demonstrated by RT-PCR.

Elemental composition of anatomically distinct regions of rat liver.

Experiments were conducted to test the commonly held assumption that analysis of a portion of rat liver is representative of the elemental concentration of the whole organ. Male Sprague-Dawley rats (initial body weight approximately 250 g) fed a chow diet or weanling male Long-Evans rats (initial body weight approximately 50 g) fed a semipurified diet with or without copper in the mineral premix were sacrificed after 4 wk on their respective diets and livers were dissected into seven portions representing major anatomical divisions of this organ. Elemental analyses by atomic absorption spectroscopy (calcium, magnesium, iron, zinc, copper, manganese), atomic emission spectroscopy (sodium, potassium), or colorimetric assay (phosphorus) demonstrated no statistically significant differences in composition of these nine elements among anatomical regions of liver.

Use of capillary electrophoresis for the characterization of human serum albumin heterogeneity.

Human serum albumin (HSA) is used in large amounts as an excipient in many biopharmaceutical formulation to prevent loss of the active ingredient through adsorption and/or degradation. Traditionally, iso-electric focusing has been used to demonstrate charge heterogeneity in HSA preparations. In an effort to develop new methods for the analysis of formulation components, a capillary zone electrophoresis method was developed for the analysis of HSA.

Characterisation of human serum albumin heterogeneity by capillary zone electrophoresis and electrospray ionization mass spectrometry.

Human serum albumin (HSA) preparations and HSA-containing recombinant human erythropoietin (rhEPO) formulations were analyzed by capillary zone electrophoresis. HSA was separated into several components by the addition of 1,4-diaminobutane to 20 mM sodium phosphate, pH 6.0 as electrophoretic buffer.

Analysis of recombinant human erythropoietin in drug formulations by high-performance capillary electrophoresis.

A high-performance capillary electrophoresis (HPCE) method was developed for the analysis of recombinant human erythropoietin (rhEPO) in final drug preparations. All products examined were formulated with large amounts of human serum albumin (HSA) which is used as a protein excipient. Due to their similar physical characteristics in solution, rhEPO and HSA could not be resolved under HPCE conditions previously developed for the separation of bulk rhEPO.

30-day oral toxicity study of domoic acid in cynomolgus monkeys: lack of overt toxicity at doses approaching the acute toxic dose.

Domoic acid was orally administered to 3 cynomolgus monkeys at doses of 0.5 mg/kg for 15 days and then at 0.75 mg/kg for another 15 days.

Ensuring recovery of intact RNA from rat pancreas.

The isolation of intact RNA from rat pancreas is compromised by autolysis and by the presence of endogenous ribonucleases. In order to ameliorate recovery we systematically investigated available RNA extraction methods and paid particular attention to the influence of frozen storage and ribonuclease inhibition strategies on overall yield and quality of RNA. Modifications to the basic procedure of Chomczynski and Sacchi (1987) are described which allow, reproducibly, to obtain rat pancreatic RNA suitable for Northern blot hybridization, RT-PCR, and differential display analysis.

Cytotoxicity of unsaturated metabolites of valproic acid and protection by vitamins C and E in glutathione-depleted rat hepatocytes.

Valproic acid (VPA) and the unsaturated metabolites, 2-ene VPA and (E)-2,(Z)-3'-diene VPA, demonstrated dose-dependent cytotoxicity in primary cultures of rat hepatocytes, as evaluated by lactate dehydrogenase (LDH) leakage. Cellular glutathione (GSH) was depleted by adding buthionine sulfoximine (BSO) to the culture medium. Induction of cytochrome P450 by pretreatment of rats with phenobarbital or pregnenolone-16 alpha-carbonitrile enhanced the cytotoxicity of parent VPA in BSO-treated hepatocytes.

Health risk assessment of Listeria monocytogenes in Canada.

In this review, the major steps used in the formulation of a health risk assessment for Listeria monocytogenes in foods are discussed. Data is given on the numbers of human listeriosis cases reported in Canada along with the current Canadian regulatory policy on L. monocytogenes.

Subchronic toxicity study of domoic acid in the rat.

Male and female Sprague-Dawley rats were dosed by gavage for 64 days with 0, 0.1 or 5 mg/kg/day domoic acid. Treated animals showed no clinical abnormalities.

Performance Assessment of the GENE-TRAK Colorimetric Probe Assay for the Detection of Foodborne Salmonella spp.

A performance assessment of the GENE-TRAK colorimetric probe assay using pure cultures and naturally contaminated foods and animal feeds underlined the high sensitivity and specificity of this DNA-rRNA diagnostic system. The probe effectively identified 110 (100%) strains of Salmonella spp. and yielded no false-positive reactions in the examination of 61 pure cultures of nonsalmonellae.

Recovery of Salmonella spp. from refrigerated preenrichment cultures of dry food composites.

Refrigerated preenrichment 72 h and selective enrichment cultures arising from 25 g analytical units of dry foods can be used to increase the analytical flexibility and productivity of laboratories for the detection of foodborne Salmonella spp. by AOAC method 994.04.

Utilizing nuclear magnetic resonance (NMR) spectroscopy for assessing nadolol racemate composition.

NMR methods were developed for the determination of the racemate composition in nadolol raw materials. With high-field instruments (400 MHz or greater) the racemate ratio may be determined by the relative heights of the t-butyl peaks, which are well enough resolved for this determination. For lower field spectrometers, the t-butyl peaks are not resolved.

Detection of Salmonella in dry foods using refrigerated pre-enrichment and enrichment broth cultures: summary of collaborative study.

A collaborative study was conducted to compare the productivity of refrigerated pre-enrichment and enrichment broth cultures with the U.S. Food and Drug Administration culture methods for detection of Salmonella.

Comparative cytotoxicity of non-steroidal anti-inflammatory drugs in primary cultures of rat hepatocytes.

The cytotoxicities of 12 non-steroidal anti-inflammatory drugs (NSAIDs) in primary monolayer cultures of rat hepatocytes were compared. Toxicity was determined by measuring the release of lactate dehydrogenase into the culture medium after 20 hr of exposure. Diflunisal was the most cytotoxic, followed, in order, by mefenamic acid, diclofenac, indomethacin, flurbiprofen, piroxicam, sulindac and ibuprofen.

Polybrene/DMSO-assisted gene transfer. Generating stable transfectants with nanogram amounts of DNA.

Polybrene/DMSO-assisted gene transfer is a simple and versatile transfection strategy capable of producing high numbers of stable transfectants from adherent monolayer cultures with low (nanogram) quantities of exogenous DNA. The procedure involves two stages: adsorption and internalization. The former is mediated by polybrene (a polycation polymer) and favors the uniform coating of target cells with polybrene-DNA complexes.