How explicable are differences between reviews that appear to address a similar research question? A review of reviews of physical activity interventions

Background Systematic reviews are promoted as being important to inform decision-making. However, when presented with a set of reviews in a complex area, how easy is it to understand how and why they may differ from one another? Methods An analysis of eight reviews reporting evidence on effectiveness of community interventions to promote physical activity. We assessed review quality and investigated overlap of included studies, citation of relevant reviews, consistency in reporting, and reasons why specific studies may be excluded. Results There were 28 included studies. The majority (n = 22; 79%) were included only in one review. There was little cross-citation between reviews (n = 4/28 possible citations; 14%). Where studies appeared in multiple reviews, results were consistently reported except for complex studies with multiple publications. Review conclusions were similar. For most reviews (n = 6/8; 75%), we could explain why primary data were not included; this was usually due to the scope of the reviews. Most reviews tended to be narrow in focus, making it difficult to gain an understanding of the field as a whole. Conclusions In areas where evaluating impact is known to be difficult, review findings often relate to uncertainty of data and methodologies, rather than providing substantive findings for policy and practice. Systematic ‘maps’ of research can help identify where existing research is robust enough for multiple in-depth syntheses and also show where new reviews are needed. To ensure quality and fidelity, review authors should systematically search for all publications from complex studies. Other relevant reviews should be searched for and cited to facilitate knowledge-building

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Thermal Tolerance of Acid-Adapted and Non-adapted Escherichia coli O157:H7 and Salmonella in Ground Beef During Storage

Thermal tolerance of acid-adapted Escherichia coli O157:H7 or Salmonella in ground beef was evaluated during storage at 4°C or –20°C. Both pathogens were adapted to acidic conditions (pH ∼4.6) by growing in tryptic soy broth supplemented with 1% glucose. A five-strain cocktail of E. coli O157:H7 or Salmonella was grown separately in TSB (pH ∼6.6) and TSB + 1% glucose for 24 h at 37°C to provide cells with or without acid adaptation. Irradiated ground beef was inoculated with either acid-adapted or non-adapted E. coli O157:H7 or Salmonella; the samples stored at 4°C were subjected to heat treatment at 62°C or 65°C on days 1, 7, 14, 21, and 28, and the samples stored at –20°C were subjected to heat treatment at 62°C or 65°C on days 1, 30, 60, 90, and 120. Decimal reduction time (D values) of the pathogens was determined as an indicator of thermal tolerance. Significantly higher D62 values were observed on days 21 and 28 for non-adapted E. coli O157:H7 stored at 4°C and on days 90 and 120 for non-adapted E. coli O157:H7 stored at –20°C (P \u3c 0.05). Higher D62 values were observed on days 21 and 28 among non-adapted Salmonella strains stored at 4°C and on day 28 for acid-adapted strains of Salmonella stored at 4°C (P \u3c 0.05). Higher D62 values for acid-adapted strains of Salmonella stored at –20°C were observed on days 30, 60, and 90 (P \u3c 0.05), when while no differences were observed in the D65 values of acid-adapted and non-adapted strains of E. coli O157:H7 and Salmonella throughout storage at both temperatures (P \u3e 0.05). This suggests that acid adaptation of foodborne pathogens provides a certain level of protection against heat treatment at lower cooking temperatures, while at higher temperatures there were no observed differences between the sensitivity of acid-adapted and non-adapted strains in an actual food system over an extended period of refrigerated and frozen storage

Application of a Multiplex Polymerase Chain Reaction Assay for the Simultaneous Confirmation of Listeria monocytogenes and Other Listeria Species in Turkey Sample Surveillance

A multiplex polymerase chain reaction was developed to simultaneously identify Listeria monocytogenes and species of the genus Listeria. Two sets of primers were used, with the first amplifying a 938-bp region of the 16S rRNA gene that is highly conserved in all Listeria species and the second amplifying a 174-bp region of the listeriolysin (hlyA) gene of L. monocytogenes. Thus, isolates of Listeria spp. yield a single 938-bp product, whereas L. monocytogenes isolates yield both the 938-bp product and a 174-bp product. The specificity of the assay was verified with all six Listeria species and 11 serotypes of L. monocytogenes, as well as nonrelated bacteria. The multiplex PCR assay was used to determine the incidence of Listeria spp., especially L. monocytogenes, in mechanically separated turkey samples (n = 150 samples). L. monocytogenes strains were selected by using the University of Vermont two-step enrichment protocol and plating to selective Palcam agar. The multiplex PCR assay was used for verification of presumptive Listeria colonies. Approximately 38% of mechanically separated turkey samples (57 of 150) yielded L. monocytogenes; an additional 18% of these samples (27 of 150) harbored other Listeria spp. Fifty-one percent (29 of 57) of the L. monocytogenes isolates were of serogroup 1, 44% (25 of 57) were of serogroup 4, and 2% (1 of 57) were assigned to serogroups other than 1 and 4

Efficacy of Ultraviolet Light Exposure Against Survival of Listeria monocytogenes on Conveyor Belts

Listeria monocytogenes has been repeatedly isolated from foods and food-processing facilities including food contact surfaces such as conveyor belts (CB). CBs are often difficult to clean and require rigorous sanitation programs for decontamination. Ultraviolet (UV) light has exhibited microbicidal properties on food contact surfaces and this study was conducted to determine the efficacy of UV against L. monocytogenes on CB made of different materials. A four-strain cocktail of L. monocytogenes (serotypes 3A, 4A, 4B, and 4C) was made to give a suspension of approximately 107 CFU/mL. CBs made from four different types of materials, (1) Ropanyl DM 8/2 A2 + 04 (belt 1), (2) Volta FRMW-3.0 (belt 2), (3) Volta FRMB-3.0 (belt 3), and (4) Ropanyl DM (belt 4), were inoculated with 1 mL of the four-strain cocktail (∼107 CFU/mL) of the bacterial suspension. CBs were treated with UV light (254 nm) for 1 and 3 sec at 5.53 and 5.95 mW/cm2. Three replications of the experiments were conducted. Two-way analysis of variance of survival populations of L. monocytogenes showed that bacterial counts were significantly reduced (p \u3c 0.05) on all belt types irrespective of UV light intensities and times of exposure. L. monocytogenes populations were reduced (p \u3c 0.05) to below detection limits on belts 1, 2, and 3 after exposure to 5.95 mW/cm2 UV light intensity for 3 sec. L. monocytogenes–inoculated CBs that were exposed to 5.53 mW/cm2showed higher (p \u3c 0.05) survival populations of L. monocytogenes compared with 5.95 mW/cm2 on all the four CBs. Belt 4 showed survival populations of L. monocytogenes ranging from 1.42 to 1.73 log10 CFU/cm2 after UV light treatment for 1 and 3 sec. UV light can be effectively used to reduce L. monocytogenes contamination on CBs

Rapid Detection of Listeria monocytogenes in Mechanically Separated Turkey Meat

The purpose of this study was to determine the level of Listeria spp., especially L. monocytogenes, in mechanically separated turkey (MST) meat. During two trials of 25 samples each, Listeria spp. were selected by using two enrichments (University of Vermont-modified I and II) and plating to selective Palcam agar base. A multiplex polymerase chain reaction (PCR) was used to confirm Listeria isolations. The specificity of the multiplex PCR assay was evaluated with reference strains of Listeria from the National Animal Disease Center (NADC) Culture Collection. The Listeria spp. yields a single 938-bp product whereas L. monocytogenes yields the 938-bp product along with a 174-bp fragment. Results from Trial I and II indicated L. monocytogenes could not be detected by PCR in the UVM enrichment due perhaps to PCR inhibitors present in poultry fats and muscle myoglobin. However the multiplex PCR performed from suspect colonies grown on Palcam indicated 48 out of 54 (89%) of the MST meat harbored Listeria spp. Of those, 32 of 48 (67%) were positive for L. monocytogenes

Biphasic Culture of Arcobacter spp.

Arcobacter spp. have recently been genetically differentiated as a genus distinct from Campylobacter. Physiologically, Arcobacter spp. are aerotolerant bacteria, while Campylobacter spp. are microaerophilic. However, since Arcobacter spp. have been difficult to grow to high population densities in broth media, alternative culture techniques were investigated. A biphasic culture system was developed in 25 cm2 tissue culture flasks. Biphasic culture, consisting of a solid phase of 10% bovine blood agar and a liquid phase of Brain Heart Infusion broth, was found to increase bacterial population densities by more than 2 log10 cycles for strains of A. butzleri and A. skirrowii. A strain of A. cryaerophilus, which was non-culturable in broth culture, attained population densities of 109 cells ml-1 in biphasic culture. Neither the addition of fetal bovine serum to the liquid nor an increase in the surface area from 25 to 75 cm2 resulted in increased cell densities

Distribution and Control of Herbicide-Resistant Italian Ryegrass (Lolium perenne L. ssp. multiflorum Lam. Husnot) in Arkansas

Italian ryegrass populations have evolved resistance to herbicides that producers rely on for weed control both in wheat and burn-down. The objectives of this research were to: test populations of Italian ryegrass from across Arkansas for resistance to glyphosate, diclofop, pinoxaden, and pyroxsulam; determine if there were any differences in control of 12 glyphosate-resistant populations in relation to glyphosate rate or application timing; determine the level of glyphosate resistance in one selected population versus a susceptible standard and a previously discovered glyphosate-resistant population; and determine the best options for controlling Italian ryegrass prior to planting crops. A total of 215 population samples were tested. On average 17% of the samples were resistant to glyphosate, 95% were resistant to diclofop, 64% were resistant to pyroxsulam, and 12% were resistant to pinoxaden. A few were resistant to all four chemistries tested. Control of glyphosate-resistant populations was improved with the high rate of glyphosate at the three- to four-tiller growth stage; however, results for individual populations were variable. When averaged across populations, no rate or timing of glyphosate controlled these resistant populations greater than 62%. One population was found to be 23 times more tolerant to glyphosate than a susceptible standard. Three field experiments were conducted for Italian ryegrass control in the spring, in no-till production in the fall, and following fall tillage. Herbicide applications in the spring were unsuccessful, especially when glyphosate is not an option. Even when postemergence (POST) treatments visually controlled ryegrass at least 80%, enough ryegrass residue remained that would cause problems with spring tillage, planting, and overall crop stand establishment. In the fall-tilled study, the residual herbicides flumioxazin plus S-metolachlor, S-metolachlor, clomazone, and pyroxasulfone applied immediately following fall tillage reduced Italian ryegrass biomass by 83 to 95% at 200 days after treatment

The preparation and properties of isolated chicken hepatocytes

Chicken hepatic parenchymal cell suspensions, isolated by an optimised collagenase digestion, were used for a study of hepatic glucose metabolism and its control in the chicken. Characterisation of this iri vitro preparation showed the parenchymal cells immediately after isolation to be similar to those of whole liver, both morphologically and metabolically. This similarity suggested that metabolic studies with isolated hepatocytes might confidently be extrapolated to the situation in the intact animal. However the preparation quality was dependent on collagenase contaminants and all preparations exhibited decreased viability throughout subsequent incubations.Glycogen metabolism in isolated hepatocyte suspensions favoured glycogenolysis and under no conditions was net glycogen synthesis observed. Gluconeogenesis from added precursors was difficult to discern with fed chicken hepatocytes due to the high basal glucose production but was readily demonstrated at a constant rate over a two hour incubation with starved chicken hepatocytes.The gluconeogenic effectiveness of precursors was generally similar in isolated hepatocytes and in chickens in vivo. The greater effectiveness of lactate compared with pyruvate, observed with both systems (unlike the rat), is probably a consequence of impaired hydrogen ion transfer during pyruvate gluconeogenesis due to the mitochondrial location of phosphoenolpyruvate carbcxykinase in the chicken. Synergistic interactions between substrates were shown to occur and be important for interpretation of results from isolated hepatocytes for extrapolation to the situation in vivo. Glycerol wasPhysiological concentrations of glucagon stimulated glycogenolysis and gluconeogenesis from precursors entering the glycolytic pathway above and below the triose phosphate dehydrogenase step. Although it was possible to assign a glucagon control point between triose phosphate and glucose in chicken liver, that between pyruvate and phosphoenol pyruvate (postulated for the rat) was not observed