Determination of the Discriminating Concentration Towards Permethrin for Surveying Resistance in Amblyomma americanum.

Amblyomma americanum Linnaeus (Ixodida: Ixodidae) is ubiquitously present throughout the southeastern United States and is capable of vectoring several pathogens. White-tailed deer are the main host for adult A. americanum. However, this tick species is a generalist that will feed on most vertebrates, including humans, deer, livestock, and pets. Management of this species can be challenging due to a lack of cost-effective strategies. Acaricides are often utilized, however, this may lead to pesticide resistance. The Food and Agriculture Organization of the United Nations (FAO) larval packet test (LPT) was performed on susceptible A. americanum to determine the lethal concentration (LC) and discriminating concentration (DC) values for permethrin. The FAO LPT was used at these pre-established values to compare levels of resistance in ticks collected from a captive deer farm and wild areas representing high and low permethrin exposure settings, respectively. Resistance ratios (RR) calculated from the LC values for the ticks collected from farmed and wild deer ranged between 1 and 2. A. americanum collected from farmed and wild deer were not found to be resistant, however, some samples had slightly elevated RRs as compared to the susceptible laboratory strain, which may suggest tolerance development. Although the A. americanum sampled in this study were not resistant to permethrin, the DC calculated in this study will allow for rapid evaluation of resistance in a permethrin resistance monitoring program such that alternate management strategies can be adopted if resistance is detected.

The density of tobacco retailers in home and school environments and relationship with adolescent smoking behaviours in Scotland.

BACKGROUND: Neighbourhood retailing of tobacco products has been implicated in affecting smoking prevalence rates. Long-term smoking usually begins in adolescence and tobacco control strategies have often focused on regulating 'child spaces', such as areas in proximity to schools. This cross-sectional study examines the association between adolescent smoking behaviour and tobacco retail outlet density around home and school environments in Scotland. METHODS: Data detailing the geographic location of every outlet registered to sell tobacco products in Scotland were acquired from the Scottish Tobacco Retailers Register and used to create a retail outlet density measure for every postcode. This measure was joined to individual responses of the Scottish Schools Adolescent Lifestyle and Substance Use Survey (n=20 446). Using logistic regression models, we explored the association between the density of retailers, around both home and school address, and smoking behaviours. RESULTS: Those living in the areas of highest density of retailers around the home environment had 53% higher odds of reporting having ever smoked (95% CI 1.27 to 1.85, p<0.001) and 47% higher odds of reporting current smoking (95% CI 1.13 to 1.91 p<0.01). Conversely, those attending schools in areas of highest retail density had lower odds of having ever smoked (OR 0.66, 95% CI 0.50 to 0.86 p<0.01) and lower odds of current smoking (OR 0.75, 95% CI 0.59 to 0.95, p<0.05). CONCLUSIONS: The density of tobacco retail outlets in residential neighbourhoods is associated with increased odds of both ever smoked and current smoking among adolescents in Scotland. Policymakers may be advised to focus on reducing the overall density of tobacco outlets, rather than concentrating on 'child spaces'.

Is local alcohol outlet density related to alcohol-related morbidity and mortality in Scottish cities?

Alcohol consumption may be influenced by the local alcohol retailing environment. This study is the first to examine neighbourhood alcohol outlet availability (on- and off-sales outlets) and alcohol-related health outcomes in Scotland. Alcohol-related hospitalisations and deaths were significantly higher in neighbourhoods with higher outlet densities, and off-sales outlets were more important than on-sales outlets. The relationships held for most age groups, including those under the legal minimum drinking age, although were not significant for the youngest legal drinkers (18-25 years). Alcohol-related deaths and hospitalisations were higher in more income-deprived neighbourhoods, and the gradient in deaths (but not hospitalisations) was marginally larger in neighbourhoods with higher off-sales outlet densities. Efforts to reduce alcohol-related harm should consider the potentially important role of the alcohol retail environment.

Role of physical activity in the relationship between urban green space and health.

OBJECTIVES: Local availability of green space has been associated with a wide range of health benefits. Possible causative mechanisms underpinning the green space and health relationship include the provision of physical activity opportunities, the stress-relieving effects of nature and the facilitation of social contacts. This study sought to investigate whether urban green space was related to individual-level health outcomes, and whether levels of physical activity were likely to be a mediating factor in any relationships found. STUDY DESIGN: Cross-sectional analysis of anonymized individual health survey responses. METHODS: Neighbourhood-level green space availability was linked to 8157 respondents to the New Zealand Health Survey 2006/07 on the basis of their place of residence. Adjusted multilevel models were constructed for four health outcomes which are plausibly related to green space via physical activity: cardiovascular disease; overweight; poor general health; and poor mental health (Short Form 36). RESULTS: The greenest neighbourhoods had the lowest risks of poor mental health [odds ratio (OR) 0.81, 95% confidence interval (CI) 0.66-1.00]. Cardiovascular disease risk was reduced in all neighbourhoods with >15% green space availability (e.g. OR 0.80, 95% CI 0.64-0.99 for those with 33-70% green space), However, a dose-response relationship was not found. Green space availability was not related to overweight or poor general health. Overall, levels of physical activity were higher in greener neighbourhoods, but adjustment for this only slightly attenuated the green space and health relationships. CONCLUSIONS: Neighbourhood green space was related to better cardiovascular and mental health in a New Zealand Health Survey, independent of individual risk factors. Although physical activity was higher in greener neighbourhoods, it did not fully explain the green space and health relationship.

The influence of geography on uptake of plastic surgery services - analysis based on bilateral breast reduction data.

The hub-and-spoke model was introduced in the National Health Service (NHS) with the goal of providing equitable access to health care for all. This study uses bilateral breast reduction (BBR) surgery to assess the success of this model in delivering equity of access for plastic surgery within a publicly funded health-care system. This study also assessed the effect of socioeconomic deprivation on patients seeking BBR. The hospital records were used to identify all patients who underwent BBR at the St. John's Hospital between 1996 and 2005 (N=1081). Patients living outside the catchment area were excluded. Realistic travel distances and times to the hospital and clinics were calculated using patients' postcodes and geographic information systems (GIS) network analysis. Carstairs deprivation scores were obtained for the residential postcode of each patient. The main findings of this study are (1) accessibility to a plastic surgery clinic is an important factor in determining whether an eligible female patient undergoes BBR and (2) most deprived parts of the catchment area accounted for a significantly greater proportion of patients.

The simple ultrastructure of the maize kinetochore fits a two-domain model.

Light microscope observations suggest there are two discrete biochemical domains in the plant kinetochore, an inner domain containing structural proteins, and an outer domain containing proteins involved in motility. We analyzed the ultrastructure of maize meiotic kinetochores following high pressure freezing and freeze substitution, a method that provides excellent sample preservation. Data from meiosis II support previous descriptions of plant kinetochores as diffuse, nearly invisible domains, sometimes nesting in a cup of darkly staining chromatin. The ultrastructure is similar in meiosis I but there are two sister kinetochores that each protrude away from the chromosome and form their own distinct kinetochore fibers. Microtubules terminate within kinetochores where their ends are splayed in a cone-shaped configuration suggestive of microtubule disassembly. We could not detect any significant substructure within the kinetochore proper. We suggest that the diffuse structure classically defined as the kinetochore represents only the outer domain of a two-domain organelle. The inner domain, known to contain chromatin-binding proteins, probably extends into the electron-dense chromatin of the primary constriction.

Ultrastructure of the host-pathogen interface in daylily leaves infected by the rust fungus Puccinia hemerocallidis.

Transmission electron microscopy was used to examine details of the host-pathogen interface in daylily leaf cells infected by the rust fungus Puccinia hemerocallidis. Samples were prepared for study by high-pressure freezing followed by freeze substitution. The outstanding preservation of ultrastructural details afforded by this fixation protocol greatly facilitated the study of this host-pathogen interface. The extrahaustorial membrane that separated each dikaryotic haustorium from the cytoplasm of its host cell was especially well preserved and appeared almost completely smooth in profile. Large aggregations of tubular cytoplasmic elements were present near haustoria in infected host cells. Many of these tubular elements were found to be continuous with the extrahaustorial membrane and conspicuous electron-dense deposits present in the extrahaustorial matrix extended into these elements. The use of gold-conjugated wheat germ agglutinin for labeling of chitin revealed that these deposits were not part of the haustorial wall. Portions of many of the tubular elements associated with haustoria were conspicuously beaded in appearance. Some tubular elements were found to be continuous with flattened cisternae that in turn bore short beaded chains. Distinctive tubular-vesicular complexes previously reported only in cryofixed rust haustoria also were found in the haustoria of P. hemerocallidis.

Illness outbreak associated with Escherichia coli O157:H7 in Genoa salami. E. coli O157:H7 Working Group.

BACKGROUND: An outbreak of Escherichia coli O157:H7 infection was identified in the spring of 1998, with a 7-fold increase in the number of laboratory-confirmed E. coli O157:H7 cases in southern Ontario. This prompted an intensive investigation by local, provincial and federal public health officials. METHODS: Case interviews of 25 people from southern Ontario were conducted using a broad food history and environmental exposure survey. Laboratory investigations involved both case and food sampling. Specimens of foods sold locally and reportedly consumed by those affected were tested. Common suppliers of suspected foods were identified by cross-referencing suppliers' lists with stores frequented by those who fell ill. A case-control study involving 25 cases and 49 age-matched controls was conducted. This was followed by a comprehensive environmental investigation of the meat processing plant identified as the source of the E. coli. RESULTS: Thirty-nine outbreak-related cases occurred between April 3 and June 2, 1998. Of the 36 case specimens tested all were positive for E. coli O157:H7. The case-control study identified Genoa salami as the most probable (odds ratio 8 [confidence interval 2-35]) source of the outbreak. Samples of Genoa salami produced by the most commonly identified supplier later tested positive for E. coli O157:H7, and the pathogen matched the same pulsed-field gel electrophoresis pattern and phage type of the case specimens. INTERPRETATION: Our investigation, which led to a national recall of the brand of dry fermented Genoa salami identified as the source of the outbreak, supports an adherence to stringent manufacturing requirements for fermented meat products. A review of the Canadian standards for fermented meat processing and the effectiveness of their implementation is warranted.

Ultrastructure of the Penetration and Infection of Pansy Roots by Thielaviopsis basicola.

ABSTRACT Transmission electron microscopy was used to study the penetration and infection of pansy roots by Thielaviopsis basicola. Events observed in 7- to 10-day-old roots produced on moist filter paper differed slightly from those in roots from 4-week-old plants washed free of potting media prior to inoculation. By 3 h postinoculation (PI), epidermal cells of roots produced on filter paper exhibited aggregated cytoplasm and papilla formation in response to germ tube tips. The presence of callose in papillae was demonstrated using immunogold labeling. Papilla formation was not effective in preventing host cell penetration. A slender infection hypha emerged from a germ tube tip and grew through a papilla. Its tip then expanded to form a globose infection vesicle. By 6 h PI, infection hyphae emerged from infection vesicles, and invaded host cells showed signs of necrosis. By 8 h PI, infection hyphae had grown into cortical cells in spite of papilla formation in these cells. By 24 h PI, distinctive intracellular hyphae were present in necrotic cortical cells. In washed roots, most epidermal cells failed to respond to invasion. Hyphae simply grew through these cells and contacted cortical cells that exhibited aggregated cytoplasm and papillae formation. Infection structures similar to those produced in epidermal cells from roots grown on filter paper then formed in cortical cells of washed roots. The fact that T. basicola formed infection structures only in cells that responded to invasion suggests that T. basicola has a more complex relationship with its host than would be expected in a nectrotrophic pathogen. We believe that T. basicola is best described as a necrotrophic hemibiotroph.

Gamma-tubulin in Chlamydomonas: characterization of the gene and localization of the gene product in cells.

In addition to their role in nucleating the assembly of axonemal microtubules, basal bodies often are associated with a microtubule organizing center (MTOC) for cytoplasmic microtubules. In an effort to define molecular components of the basal body apparatus in Chlamydomonas reinhardtii, genomic and cDNA clones encoding gamma-tubulin were isolated and sequenced. The gene, present in a single copy in the Chlamydomonas genome, encodes a protein with a predicted molecular mass of 52,161 D and 73% and 65% conservation with gamma-tubulin from higher plants and humans, respectively. To examine the distribution of gamma-tubulin in cells, a polyclonal antibody was raised against two peptides contained within the protein. Immunoblots of Chlamydomonas proteins show a major cross-reaction with a protein of Mr 53,000. In Chlamydomonas cells, the antibody stains the basal body apparatus as two or four spots at the base of the flagella and proximal to the microtubule rootlets. During cell division, two groups of fluorescent dots separate and localize to opposite ends of the mitotic apparatus. They then migrate during cleavage to positions known to be occupied by basal bodies. Changes in gamma-tubulin localization during the cell cycle are consistent with a role for this protein in the nucleation of microtubules of both the interphase cytoplasmic array and the mitotic spindle. Immunogold labeling of cell sections showed that gamma-tubulin is closely associated with the basal bodies. The flagellar transition region was also labeled, possibly indicating a role for gamma-tubulin in assembly of the central pair microtubules of the axoneme.

Ochratoxin a in retail flour.

Flour delivered to a school in the Bournemouth area was found by thinlayered chromatography to contain up to 6.25 mg/dg of ochratoxin. A. Penicillium cyclopium, a fungus known to produce this toxin, was found in discoloured portions of the caked flour. Ochratoxin was also found in a second sack delivered to the school, but not in samples of sound flour or in six samples of flour of varying quality from other sources. The health risk did not appear to be serious.