Inactivation of the gene encoding the cationic antimicrobial peptide resistance factor MprF increases biofilm formation but reduces invasiveness of Listeria monocytogenes.

AIMS: To understand the genetics involved in surface attachment and biofilm formation of Listeria monocytogenes. METHODS AND RESULTS: An in vitro screen of a Himar1 transposon library of L. monocytogenes strain 15G01 identified three transposants that produced significantly different biofilm levels when compared to the wild-type strain; two mutants exhibited enhanced biofilm formation and one produced less biofilm biomass than the wild-type. The mutant 15G01 mprF::Himar1, which had a transposon insertion in the mprF gene, was selected for further analysis. The mutant produced a more densely populated biofilm on solid surfaces such as stainless steel and polystyrene, as determined using scanning electron and light microscopy. The 15G01 mprF::Himar1 mutant remained viable in biofilms, but showed an increase in sensitivity to the cationic antimicrobial gallidermin. The mutant also displayed reduced invasiveness in CaCo-2 intestinal cells, suggesting virulence properties are compromised by the inactivation of mprF. CONCLUSIONS: Biofilm formation and gallidermin resistance of L. monocytogenes is influenced by mprF, but this trait is associated with a compromise in invasiveness. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of pathogenic microorganisms in the food processing environment can cause a significant problem, especially when these microorganisms are established as biofilms. This study shows that the inactivation of the mprF gene results in enhanced biofilm formation and abiotic surface attachment of L. monocytogenes.

Prevalence, characteristics and ecology of Vibrio vulnificus found in New Zealand shellfish.

AIMS: In New Zealand, there have been no known cases of foodborne diseases linked to Vibrio vulnificus and shellfish consumption, but two cases of wound infection have been reported. We evaluated the distribution, the effect of environmental parameters, the pheno-genotypic profile and the growth characteristics of strains isolated from shellfish. METHODS AND RESULTS: Vibrio vulnificus was present in 13·6% of Pacific oysters and not found in any dredge oyster or Greenshell(™) mussel samples. Eleven isolates belonged to biotype 1 while nine appeared to be variants of biotype 1. Nineteen isolates were genotype E (type A) and just one was genotype C (type B). Some isolates were more resistant to high salt concentrations (>30‰) than others, but not different from ATCC 27562. CONCLUSIONS: Vibrio vulnificus were low in numbers, mostly belonging to genotype E, 16S rRNA type A and biotype 1. No relationship or adaptability to high salinity was observed, but seawater temperature was a strong predictor of bacterial numbers in shellfish. SIGNIFICANCE AND IMPACT OF THE STUDY: We report, for the first time, the characterization of V. vulnificus isolated from New Zealand shellfish and its long-term distribution and prevalence. This information will help the authorities on risk assessments.

Long-term study of Vibrio parahaemolyticus prevalence and distribution in New Zealand shellfish.

The food-borne pathogen Vibrio parahaemolyticus has been reported as being present in New Zealand (NZ) seawaters, but there have been no reported outbreaks of food-borne infection from commercially grown NZ seafood. Our study determined the current incidence of V. parahaemolyticus in NZ oysters and Greenshell mussels and the prevalence of V. parahaemolyticus tdh and trh strains. Pacific (235) and dredge (21) oyster samples and mussel samples (55) were obtained from commercial shellfish-growing areas between December 2009 and June 2012. Total V. parahaemolyticus numbers and the presence of pathogenic genes tdh and trh were determined using the FDA most-probable-number (MPN) method and confirmed using PCR analysis. In samples from the North Island of NZ, V. parahaemolyticus was detected in 81% of Pacific oysters and 34% of mussel samples, while the numbers of V. parahaemolyticus tdh and trh strains were low, with just 3/215 Pacific oyster samples carrying the tdh gene. V. parahaemolyticus organisms carrying tdh and trh were not detected in South Island samples, and V. parahaemolyticus was detected in just 1/21 dredge oyster and 2/16 mussel samples. Numbers of V. parahaemolyticus organisms increased when seawater temperatures were high, the season when most commercial shellfish-growing areas are not harvested. The numbers of V. parahaemolyticus organisms in samples exceeded 1,000 MPN/g only when the seawater temperatures exceeded 19°C, so this environmental parameter could be used as a trigger warning of potential hazard. There is some evidence that the total V. parahaemolyticus numbers increased compared with those reported from a previous 1981 to 1984 study, but the analytical methods differed significantly.

A randomised, double-blinded, placebo-controlled study on the efficacy of a unique extract of green-lipped mussel (Perna canaliculus) in horses with chronic fetlock lameness attributed to osteoarthritis.

REASONS FOR PERFORMING STUDY: Lyophilised products from green-lipped mussel (Perna canaliculus[LPPC]) are used to orally treat horses with osteoarthritis (OA). However, no randomised, controlled or double-blinded studies on the efficacy of this treatment in horses have been reported to date. OBJECTIVE: To investigate the effects of a unique LPPC (Biolane)(1) in improving clinical signs of OA in the fetlock. METHODS: Data were analysed from 26 horses with primary fetlock lameness in a controlled, randomised and double-blinded, multi-centre clinical trial. The study design was a partial crossover with a washout period and consisted of 19 horses treated with LPPC and 20 with a placebo. Horses were dosed orally with 25 mg/kg bwt/day LPPC or placebo for 56 days. Efficacy was evaluated by clinical assessment of lameness, passive flexion, pain, swelling and heat in the affected joint. Relationships between variables were analysed using an ordinal logistic model with random effects for horse and horse x treatment according to a modified intention-to-treat analysis. RESULTS: Clinical evaluation of horses with a fetlock lameness treated with LPPC showed a significant reduction in severity of lameness (P<0.001), improved response to the joint flexion test (P<0.001) and reduced joint pain (P = 0.014) when compared with horses treated with placebo. CONCLUSIONS: The LPPC significantly alleviated the severity of lameness and joint pain and improved response to joint flexion in horses with lameness attributable to OA in the fetlock.

Characterization of intestinal inflammation and identification of related gene expression changes in mdr1a(-/-) mice.

Multidrug resistance targeted mutation (mdr1a (-/-) ) mice spontaneously develop intestinal inflammation. The aim of this study was to further characterize the intestinal inflammation in mdr1a (-/-) mice. Intestinal samples were collected to measure inflammation and gene expression changes over time. The first signs of inflammation occurred around 16 weeks of age and most mdr1a (-/-) mice developed inflammation between 16 and 27 weeks of age. The total histological injury score was the highest in the colon. The inflammatory lesions were transmural and discontinuous, revealing similarities to human inflammatory bowel diseases (IBD). Genes involved in inflammatory response pathways were up-regulated whereas genes involved in biotransformation and transport were down-regulated in colonic epithelial cell scrapings of inflamed mdra1 (-/-) mice at 25 weeks of age compared to non-inflamed FVB mice. These results show overlap to human IBD and strengthen the use of this in vivo model to study human IBD. The anti-inflammatory regenerating islet-derived genes were expressed at a lower level during inflammation initiation in non-inflamed colonic epithelial cell scrapings of mdr1a (-/-) mice at 12 weeks of age. This result suggests that an insufficiently suppressed immune response could be crucial to the initiation and development of intestinal inflammation in mdr1a (-/-) mice.

Clinical efficacy and tolerance of an extract of green-lipped mussel (Perna canaliculus) in dogs presumptively diagnosed with degenerative joint disease.

AIM: To evaluate the efficacy and tolerance of an extract of green-lipped mussel (GLME) in the management of mild-to-moderate degenerative joint disease (DJD) in dogs. METHODS: Eighty-one dogs presumptively diagnosed with DJD were treated orally daily with either GLME or a placebo for 56 days, in a double-blind, placebo-controlled study. In an uncontrolled open-label extension to the study, all dogs were treated with GLME for an additional 56 days (from Days 57-112). Clinical signs were subjectively scored by the owners, and findings of detailed musculoskeletal examinations were scored by one veterinarian. Efficacy was assessed from a qualitative comparison of the proportion of dogs with improved clinical signs, and a quantitative comparison of the scores of the musculoskeletal examinations, between groups. Haematological and biochemical analyses and reports by owners of possible adverse drug reactions were used to screen for evidence of toxicity. RESULTS: There was close agreement between assessments by the veterinarian and owners. The clinical signs of DJD in both GLME-treated and placebo groups improved significantly over baseline by Day 28; this improvement continued over the entire course of the study. There were no significant differences between groups on Day 28. On Day 56, a higher proportion of dogs in the GLME-treated group had improved clinical signs (p=0.018), and GLME-treated dogs had marginally better (p=0.053) musculoskeletal scores than dogs in the placebo group. The differences between the groups were no longer apparent by Day 112, by which time the former placebo group had been receiving GLME for 56 days in the open-label phase of the study. The proportion of dogs in the former placebo group that had improved by Day 112 (29/32; 91%) was significantly greater (p=0.012) than the proportion improved at Day 56 (15/37; 41%). No signs of toxicity were apparent. CONCLUSIONS AND CLINICAL RELEVANCE: GLME had a beneficial effect on the clinical signs of dogs presumptively diagnosed with mild-to-moderate DJD. Long-term therapy may be required before improvement is apparent.

Suppression of the cysteine protease, aleurain, delays floret senescence in Brassica oleracea.

An aleurain-like protein, BoCP5, is up-regulated during harvest-induced senescence in broccoli floret and leaf tissue. BoCP5 is most closely related to an Arabidopsis protein (91%, AAF43041) and has 71% identity to barley aleurain (P05167). The mRNA for this gene accumulates within 6 h after harvest in broccoli florets, and its expression is reduced in tissue that has been held in senescence-delaying treatments (e.g. water, sucrose feeding, controlled atmosphere). The gene is also expressed in leaves during aging-related and harvest-induced senescence. Analysis of protein bands that cross-react with antibodies raised to the bacterial BoCP5 fusion protein, revealed prominent immunoreactive bands at ca. 26, 28, 31, and 38 kD in floret tissue. The 31 kD band was absent in protein extracts from leaf tissue. Agrobacterium-mediated transformation was used to produce transgenic broccoli plants with down-regulated BoCP5. A reduction in the postharvest expression of BoCP5 in floret tissue was achieved for four transgenic lines in the current study. In three of these lines postharvest floret senescence (yellowing) was delayed, and florets contained significantly greater chlorophyll levels during postharvest storage at 20 degrees C than wild-type plants. Line 4 showed the greatest down-regulation of BoCP5, and in this line postharvest protease activity remained at pre-harvest levels, and the yield of soluble proteins extracted from florets after harvest was significantly greater than that of wild-type tissue.

Schoolbag weight and musculoskeletal symptoms in New Zealand secondary schools.

The weight of schoolbags and the prevalence of musculoskeletal symptoms amongst 140 students (70 third form students comprising 35 females and 35 males, and 70 sixth form students comprising 35 females and 35 males) from five New Zealand secondary schools was investigated. Schoolbag weight for third form students (mean age 13.6 years) was 13.2% of their body weight, while for sixth form students (mean age 17.1 years) it was 10.3% of their body weight. These weights may exceed the recommended guideline load limits for adult industrial workers. Musculoskeletal symptoms were reported by 77.1% of the students. Symptoms were most prevalent in the neck, shoulders, upper back and lower back. Although musculoskeletal symptoms are believed to be multifactorial in origin, the carriage of heavy schoolbags is a suspected contributory factor and may represent an overlooked daily physical stress for New Zealand secondary school students.

How safe is cycling with a schoolbag?

This study was undertaken as a preliminary investigation to compare cycling errors and sudden stopping distance in secondary students traversing an obstacle course on their bicycle with and without a schoolbag, to determine if further studies of cycling accident aetiology amongst children were warranted. Twenty children cycled as fast as they could around an obstacle course. Each child undertook two separate trials, about an hour apart on a morning of the same day. The children traversed the course one at a time in turn using their own bicycle and wearing their own usual school clothes. For the first trial they did not carry a schoolbag. On the second trial they carried a schoolbag weighing 6 kg. There were no significant differences in the number of cycling errors made by the children when traversing the obstacle course with and without a schoolbag. However, the children generally took longer to complete the course when carrying the schoolbag and stopping distances were greater. It was not possible to be certain that these findings were genuine or whether the effect of carrying the schoolbag was reduced by increased familiarity with the course, since all of the children first traversed the course without a schoolbag and then with one. It is concluded that there is some justification for conducting further studies to explore the implications of carrying schoolbags on cycling accident aetiology amongst children.

Comparison of four different backpacks intended for school use.

Four backpacks were evaluated for their desireability for use as school bags. Three of the four backpacks were specifically designed for school use based on previous research and ergonomic principles while the fourth (standard) backpack was chosen from two backpacks that their manufacturer considered to be the most likely to be used as a school bag. Twelve school students evaluated each of the backpacks firstly by examining them, again after donning them and again after walking with them on a treadmill by completing a questionnaire asking about the appearance, function and comfort of each backpack. On initial examination, the standard backpack was the most favoured but as functionality became increasingly important during the treadmill walk, the backpack which was designed specifically for school use and had two major compartments, substantial back padding and side compression straps became the most favoured. This particular design of backpack was reported as having the greatest practicality, being the least physically demanding and allowing the greatest balance and ease of walking. The results of this study suggest that school student's preference of backpack may change from when they first examine a prospective backpack to when they have used it. The study also shows that school students' preferred attributes in a backpack may shift over this time from 'style and image' to 'function and fit'.

Subjective perceptual methods for comparing backpacks in the field.

Subjective perceptual methods have provided useful information in the laboratory about small differences in backpack design when physiological and biomechanical comparisons are ineffective, but have never been used in the field. This study therefore evaluated, in a controlled field trial with 10 male participants, the suitability of quantitative and qualitative subjective perceptual approaches to distinguish between subtle design differences in two backpacks, each loaded to 15 kg. In addition, initial quantitative subjective impressions about the two backpacks during a 15 min simulated 'in-shop' trial were compared with post-field trial backpack preference. In the simulated 'in-shop' trial the participants 'tried out' the backpack in a manner that was very similar to the way that they would normally try out a backpack as if they were considering buying one in an 'outdoor' shop. It included donning and doffing the pack several times and walking around the room wearing the backpack. In the controlled field trial, participants carried the two backpacks for approximately 15 min around a 1313 m hilly outdoor track at a self-selected walking pace which elicited a moderate exercise intensity. Seven participants preferred backpack A. Three preferred backpack B. The qualitative approach, which required participants to provide free-format written responses to semi-structured open-ended questions immediately after the field trial, successfully identified specific reasons underlying participants' preferences. The main reasons for preferring backpack A were better balance, weight distribution, stability up and down hill and over obstacles, fewer pressure points on their back and easier strap location and adjustment. The quantitative approach, which involved participants responding to written post-field trial questions on visual analogue or category ratio rating scales, was generally unsuccessful in distinguishing between backpacks. Thus, qualitative subjective perceptual methods appeared to be more useful than quantitative ones in distinguishing between backpacks and in identifying positive and negative design features under controlled field conditions in which participants carry a backpack at a moderately intense self-selected exercise level. However, since the quantitative approach had been successful in distinguishing between backpacks in an earlier similar study, in which participants exercised more intensely by walking uphill on a treadmill at a fixed pace, it is possible that the quantitative subjective perceptual approach may be capable of distinguishing between backpacks in the field if a fixed pace eliciting higher exercise intensity were to be used. Finally, since quantitative responses to questions about the backpacks after a short simulated 'in-shop' trial closely agreed with participants' post-field trial overall backpack preference, it is concluded that initial subjective impressions may be a good guide to backpack preference after limited field usage.

Prediction of foaling using mammary secretion constituents.

AIMS: To test published models for predicting time of foaling using data derived from prepartum mammary secretions and to develop a new model based on concentrations of mammary secretion constituents that accurately predicts time of foaling in Thoroughbred mares. METHODS: Concentrations of sodium, potassium, calcium, citrate and lactose were measured in prepartum mammary secretions of 20 Thoroughbred mares in the 2 weeks before expected date of foaling. Models to predict time of foaling were fitted to data based on absolute concentration, change in concentration, and percentage change in concentration of mammary secretion constituents in relation to actual intervals to foaling. RESULTS: Concentrations of potassium, calcium, citrate and lactose increased, and concentration of sodium decreased as foaling approached but variation between mares was large. Models to predict time of foaling based on percentage change in electrolyte concentrations were less accurate than those based on absolute concentration and change in concentration. When data from this study were fitted to two previously published models, the statistical sensitivity, specificity, and positive and negative predictive values of both models were lower than those originally reported. CONCLUSIONS: The use of prepartum equine mammary secretion electrolyte concentrations for prediction of time of foaling is unreliable, due to large variation in both absolute concentrations and change in concentrations between mares. Models that use a combination of mammary secretion electrolytes and physical and behavioural factors may better predict foaling than those based on mammary secretions alone.

The weight and use of schoolbags in New Zealand secondary schools.

The weight and use of schoolbags amongst 140 students (70 third form students comprising 35 females and 35 males, and 70 sixth form students comprising 35 females and 35 males) from five New Zealand secondary schools was investigated. Third form students, who were smaller in stature and weight than sixth form students, were found to carry 13.2% of their body weight in schoolbags, while sixth form students carried 10.3% of their body weight. Third form students reported carrying their schoolbags for a longer period of time than sixth form students. Third form students also had less access to lockers to store their schoolbooks and supplies as only one of the five schools investigated provided lockers for third form students, whereas four of the five schools provided lockers for sixth form students. Most students used backpacks to transport their supplies, and these were predominantly carried on two shoulders. Heavy schoolbags, long carriage durations and lack of access to lockers amongst third formers, could contribute to the production or maintenance of musculoskeletal symptoms. This study suggests that third form students may be at a higher risk of developing musculoskeletal symptoms than sixth form students.

A comparison of bacterial adherence to bare hands and gloves following simulated contamination from a beef carcass.

One of the risks for contamination of edible product in the pre-inspection area of processing lines in meat plants is cross contamination. This can occur directly as a result of carcass-to-carcass contact or indirectly via knives or the hands of butchers. Standard procedures require that operators rinse their hands and knives to remove any visible contamination. In New Zealand, protective gloves are not allowed in the pre-inspection area because they are considered a potential risk for cross contamination until the carcasses have passed the final meat inspection. However, the risk of injury to the bare hands is as high in this area as in other parts of the plant, where such gloves are permitted. There is therefore a need to evaluate the risk of bacterial cross contamination via bare hands and via protective gloves. The present study compared bacterial adherence to bare hands and to gloves after rinsing for 5 s in a shower of water at 40 degrees C and after rinsing gloves in hotter water (60 degrees C) following simulated contact with the hide of a recently slaughtered animal. Under laboratory conditions there were no statistically significant differences between bacterial adherence to bare hands or to gloves rinsed in water at 40 degrees C or 60 degrees C.

Development of reference intervals for the large intestinal transit of radiopaque markers in dogs.

Ten healthy dogs were fed 30 1.5 mm and 10 5 mm radiopaque markers (BIPS, MedID, Grand Rapids) mixed with sufficient quantities of a high fibre diet to meet 25% of their estimated daily caloric requirements. Abdominal radiographs were made at two hour intervals until 90% of the small and large markers had left the colon. The mean residence times (MRT) of each size of marker in the proximal, distal and total colon were calculated using kinetic analysis. The MRT's of the small markers were 4.9 hours (SD 4.4), 7.1 hours (SD 3.3) and 12.0 hours (SD 7.1) respectively. The MRT's of the large markers were not significantly different from the small markers except in the proximal colon where they were significantly shorter (3.2 hours, SD 2.3). Reference colonic filling and colonic transit curves for both sizes of markers were constructed. These may be useful to detect abnormal colonic transit in dogs.

Sensory and hedonic judgments of common foods by lean consumers and consumers with obesity.

OBJECTIVE: To establish differences between lean subjects and subjects with obesity in subjective reports of predominant taste and texture attributes of common foods, and the relationships of these qualities and foods with overall liking. RESEARCH METHODS AND PROCEDURES: Twenty lean (body mass index: 20 to 25 kg/m2) nondieting healthy adults and 23 (body mass index: > or = 30 kg/m2) nondieting healthy adults with obesity assigned ratings for pleasantness and predominant sensory attributes to 50 common foods in 14 food groups using a questionnaire. They completed the Dutch Eating Behavior Questionnaire. Body composition was assessed by bioelectrical impedance. RESULTS: There were no significant group differences between pleasantness scores overall; however, lean subjects assigned higher scores to fruits and vegetables, to foods self-classified as sweet and as salty/savory, and to foods grouped in the highest and lowest quintiles of percentage food energy from fat. There were no group differences in free-choice texture descriptors applied to foods, but correspondence analysis revealed that subjects with obesity associated coarse, slippery, tough, and fatty textures with "dislike extremely," whereas lean subjects associated grainy, moist, doughy, and fibrous texture with "like extremely." Analyses reduced texture terms to 39 key descriptors for use in subsequent work. Groups did not significantly differ in reported external or restrained eating behaviors, but subjects with obesity scored significantly higher for reported emotional eating. DISCUSSION: Differences in preferences for listed common foods exist between weight status groups according to taste, food group, and texture. Consumers can make textural descriptions of foods that could be used to assess sensory and hedonic qualities of actual food choices.

Methodological approaches to assessing risk perceptions associated with food-related hazards.

The psychometric approach developed by Slovic and his co-workers has been effectively used to assess risk perceptions associated with different food-related hazards. However, further examination (using questionnaire data and partial correlation techniques) has indicated that technological hazards are highly differentiated from lifestyle hazards, in terms of both hazard control and knowledge about the hazard. Optimistic bias was also seen to vary between hazards. Further research has focused on a particular hazard, genetic engineering. Risk perceptions associated with genetic engineering are underpinned by ethical concern and questions relating to perceived need for the technology, as well as perceptions of risk or harm. However, increasing the specificity of hazard stimuli was found to alter the factor structure of underlying risk perceptions. The utility of preference mapping procedures in determining individual differences in trust in risk regulators is also discussed.

The elaboration likelihood model and communication about food risks.

Factors such as hazard type and source credibility have been identified as important in the establishment of effective strategies for risk communication. The elaboration likelihood model was adapted to investigate the potential impact of hazard type, information source, and persuasive content of information on individual engagement in elaborative, or thoughtful, cognitions about risk messages. One hundred sixty respondents were allocated to one of eight experimental groups, and the effects of source credibility, persuasive content of information and hazard type were systematically varied. The impact of the different factors on beliefs about the information and elaborative processing examined. Low credibility was particularly important in reducing risk perceptions, although persuasive content and hazard type were also influential in determining whether elaborative processing occurred.

Acute effects on mood and cognitive performance of breakfasts differing in fat and carbohydrate content.

Sixteen subjects consumed low-fat/high-carbohydrate (LFHC), medium-fat/ medium-carbohydrate (MFMC), high-fat/low-carbohydrate (HFLC) iso-energetic breakfasts and no breakfast in a counterbalanced order on four separate days. The LFHC breakfast was similar in macronutrient composition, though not in meal size (more kcal) and types of foods offered, to the habitual breakfast of the subjects. A battery of cognitive performance tasks together with mood and appetite ratings were completed before and during the 3 h following breakfast. Results showed no clear differences in performance between the four dietary conditions, but significant effects on mood were observed. Mood improved (a decline in fatigue/dysphoria) following the LFHC breakfast compared to the other meals. The findings show that the macronutrient content of breakfast, independent of energy value and oro-sensory qualities, can exert small but reliable effects on subsequent mood, and suggest that deviation from habitual meal composition can produce a relative decline in mood state. These conclusions are supported by results from a previous study of the effects of lunch which found very similar relationships between meal composition, habitual choices and postprandial mood changes.