Detection of cutaneous myiasis in sheep using an 'electronic nose'.

Cutaneous myiasis (flystrike), in Australia caused primarily by Lucilia cuprina [Diptera: Calliphoridae], is a debilitating, painful and potentially lethal disease of sheep. Early detection of flystrike is difficult and continual flock surveillance is required to enable timely treatment of struck sheep. Electronic nose technology offers the potential for early and automated detection of flystrike. An electronic nose consisting of six metal oxide semiconductor sensors and temperature and humidity sensors was used to measure odours collected by dynamic headspace sampling during flystrike development in four experiments and from urine- and faeces-stained fleece in one experiment. Non-linear signal measurement techniques and linear discriminant analysis (LDA) were used to extract signal features and process those features for analysis of categorical separation of odour groups. The results from LDA indicated that the electronic nose accurately distinguished flystrike odour on days 1, 2 and 3 of development from that of dry wool in all experiments (P<0.05). The electronic nose was also able to discriminate flystrike odour on the day of larval implantation (day 0) in three of the four studies. In the experiment with urine- and faeces-stained wool, these odours were accurately distinguished from both dry wool and flystrike (P<0.05). This study provides proof-of-concept for the detection of flystrike using electronic nose technology. Practical methods for collection of odour in the field and suitable detection algorithms will be required for development to commercial application.

Strategic use of crutching and dicyclanil to protect unmulesed sheep against breech strike.

OBJECTIVE: To test strategies for the application of dicyclanil and mid-season crutching to maximise protection of unmulesed sheep against breech strike. PROCEDURE: Three hundred and eighty unmulesed Merino weaners were randomly allocated to four groups either left untreated or treated by different strategies with 50 g/L dicyclanil. Treatments included breech treatment alone and breech plus body treatment, with two application times, immediately after shearing and 6 weeks after crutching or shearing. To assess protection, larval implants with newly hatched Lucilia cuprina larvae were applied to 10 different sheep from each group at 3, 4, 5 and 6 months after crutching and shearing and assessed for the development of strike at 48 hours. The concentration of dicyclanil was measured in wool samples clipped from the breeches of the test sheep. RESULTS: All dicyclanil treatments gave significant reduction in strike in comparison to controls up until 4 months after crutching but protection in the sheep treated immediately after shearing had waned at 5 months. Treating at 6 weeks after crutching provided significant reduction (P < 0.05) in strike for 6 months. Results for strike incidence immediately after shearing and concentration of dicyclanil in the breech wool also suggested improvements in protection by delaying treatment for 6 weeks. CONCLUSION: In most environments it should be possible to protect unmulesed sheep against breech strike with a carefully planned integrated control program incorporating strategically timed crutching, shearing and dicyclanil application. Delaying treatment with dicyclanil to at least 6 weeks after shearing or crutching increased the protection provided in comparison to treatment immediately after shearing.

Sustaining self-regulatory efficacy and psychological outcome expectations for postnatal exercise: effects of a group-mediated cognitive behavioural intervention.

OBJECTIVE: The objective of the current investigation was to examine if the effects of a group-mediated cognitive behavioural counselling plus exercise intervention were superior to the effects of a standard exercise care condition on postnatal mothers' self-regulatory efficacy (SRE), outcome expectations (OEs) and self-directed physical activity (PA). DESIGN: The design of the study consisted of two intervention conditions; group-mediated cognitive behavioural counselling plus exercise (GMCB) and standard exercise (SE). Each condition consisted of two phases; a 4-week supervised, centre-based intensive exercise training phase followed by a 4-week home-based phase. METHODS: Participants were 57 postnatal women randomly assigned to conditions (SE: N=31; GMCB: N=26). Measures of SRE and OEs were assessed prior to and following the centre-based aspect of the intervention. Physical activity was measured following the intensive exercise training phase as well as the home-based phase. RESULTS: GMCB participants' SRE and OEs were sustained during the intervention whereas those of SE participants declined. GMCB participants also reported significantly greater time spent engaging in self-directed PA at the conclusion of the intensive and home-based phases. Mediation analysis revealed that SRE partially mediated the relationship between intervention condition and post home-based PA as confirmed by a significant sobel test. CONCLUSIONS: These findings suggest that a theory-based GMCB counselling plus exercise intervention is superior to the SE condition in sustaining SRE and OEs, and in promoting greater self-directed PA. SRE partially mediated the relationship between intervention condition and post home-based PA supporting the targeting of that variable for change as part of the intervention.

Resistance to insect growth regulator insecticides in populations of sheep lice as assessed by a moulting disruption assay.

Low-volume, backline applications with the benzoylphenyl urea insecticides triflumuron and diflubenzuron represent in excess of 70% of treatments for the control of sheep lice, Bovicola ovis (Schrank) (Phthiraptera: Trichodectidae), in Australia. Reports of reduced effectiveness from 2003 and subsequent controlled treatment trials suggested the emergence of resistance to these compounds in B. ovis populations. A laboratory assay based on the measurement of moulting success in nymphs was developed and used to assess susceptibility to diflubenzuron and triflumuron in louse populations collected from sheep where a control failure had occurred. These tests confirmed the development of resistance to triflumuron and diflubenzuron in at least two instances, with estimated resistance ratios of 67-94X at LC(50).

Measuring quality of life in multiple sclerosis: not as simple as it sounds.

Data from a clinical study presented an opportunity to examine the psychometric properties of the Leeds Multiple Sclerosis Quality of Life scale (LMSQoL), which has undergone limited psychometric evaluation. LMSQoL and Multiple Sclerosis Quality of Life-54 (MSQoL-54) data were collected from 90 people with multiple sclerosis (MS) living in the community. Standard psychometric methods to examine data quality, scaling assumptions, scale to sample targeting, reliability, validity, and responsiveness were employed. The LMSQoL satisfied criteria for data quality (no missing data), scaling assumptions (item-total correlations: 0.24-0.56), reliability (Cronbach's alpha: 0.71), and demonstrated responsiveness (effect size: 0.34). Correlations between the LMSQoL and MSQoL-54 physical (range: -0.02 to -0.50) and emotional subscales (range: -0.38 to -0.65) were similar; the magnitude and pattern was not consistent with predictions based on the construct purported to be measured by the LMSQoL. The LMSQoL satisfied many psychometric criteria in this small study, however, it was difficult to interpret the validity data. From this, two fundamental measurement issues are highlighted. Firstly, current methods of examining rating scales provide only circumstantial evidence of validity; secondly, health-rating scales should be developed on the basis of clear conceptual definitions.

A pilot investigation of the hypoalgesic effects of transcutaneous electrical nerve stimulation upon low back pain in people with multiple sclerosis.

OBJECTIVE: To investigate the hypoalgesic effects of transcutaneous electrical nerve stimulation (TENS) upon low back pain (LBP) in people with multiple sclerosis (MS). DESIGN: A randomized double-blind placebo controlled clinical pilot study. SUBJECTS AND SETTING: Fifteen people with MS were recruited and randomly allocated to one of the following groups under double blind conditions (n = 5 per group): TENS 1 (4 Hz, 200 micros), TENS 2 (110 Hz, 200 micros), placebo TENS. INTERVENTIONS: Treatment was applied for 45 minutes three times a week for six weeks with a four-week follow-up. OUTCOME MEASURES: The following outcome measures were taken at weeks 1, 6, and 10: visual analogue scale (VAS) (for current LBP, right leg pain, left leg pain); Leeds Multiple Sclerosis Quality of Life Questionnaire; Roland Morris Disability Questionnaire; Short Form-36 (SF-36) Version 1; and the McGill Pain Questionnaire (MPQ). VAS for current LBP, right and left leg pain were also taken before and after treatment, and once a week during the follow-up period. RESULTS: Analysis showed no statistically significant effects for any of the data. However, both active treatment groups showed a trend of improvement in the majority of the outcome measures. CONCLUSION: Active TENS was more effective than placebo TENS in decreasing VAS scores following each treatment although results were not statistically significant. Further work in this area is warranted and should include a larger number of participants in the form of a randomized controlled clinical trial to determine the efficacy of this modality.

Transcutaneous electrical nerve stimulation (TENS): the effect of electrode placement upon cutaneous blood flow and skin temperature.

In the current study the effect of electrode placement on cutaneous blood flow and skin temperature were assessed using laser Doppler flowmetry. Following approval from the University's ethical committee, 30 subjects were recruited (15 male: 15 female) and randomly assigned to a control or one of two treatment groups (n=10 all groups). TENS was applied either over the median nerve or to the Hegyu acupuncture point (L.I.4) for 15 minutes. Blood flow and skin temperature data were recorded during TENS and for 15 minutes post TENS. Analysis of results showed significant differences between groups for cutaneous blood flow (p=0.0001; repeated measures ANOVA). There was a significant increase in blood flow in the TENS median nerve group compared with the other two groups during TENS application. No significant changes in skin temperature were observed between groups. This study demonstrates that the effect of TENS upon cutaneous blood flow is dependent upon electrode placement sites.

The effect of high- and low-frequency transcutaneous electrical nerve stimulation upon cutaneous blood flow and skin temperature in healthy subjects.

The reported non-analgesic effects of transcutaneous electrical nerve stimulation (TENS) include alterations to the local circulation; however, research in this area has produced equivocal findings. In the present study, the effect of low- (4 Hz) and high-frequency (110 Hz) TENS on forearm skin blood perfusion was assessed using laser Doppler flowmetry. The effect on skin temperature was also assessed using a skin thermistor. Thirty healthy human volunteers were recruited and randomly assigned to a control or one of the two treatment groups. TENS was applied to the skin overlying the median nerve under double-blind conditions for 15 min. Blood flow and skin temperature readings were recorded pre-TENS, during TENS application and continued for 15 min post-TENS application. Analysis of results showed significant increases in blood perfusion during the treatment period in the low-frequency group when compared to the other two groups (P = 0.0106; ANOVA). No significant changes in skin temperature were observed. The results of this study demonstrate that low-frequency TENS produces a local increase in cutaneous blood flow.

The effect of interferential therapy upon cutaneous blood flow in humans.

The aim of the current controlled and blinded study was to investigate the effect of various interferential current frequencies upon cutaneous blood flow in humans using laser Doppler flowmetry, in an attempt to define the physiological mechanisms involved. Following approval from the university's ethical committee, 50 healthy volunteers (25 male, 25 female; age 18-34 years) were randomly allocated into one of five experimental groups: (i) control; neither suction nor interferential current was applied, (ii) placebo; suction only was applied, (iii) IFT 1; 10-100 Hz beat frequency applied, (iv) IFT 2; 80-100 Hz beat frequency applied, and (v) IFT 3; 10-20 Hz beat frequency applied. In the IFT groups, interferential currents were applied through four suction electrodes positioned to target the quadriceps femoris muscle. The following parameters were used in all IFT groups: 125 micros pulse duration, 4 kHz carrier frequency and a 6/6 sweep. In IFT groups 1 and 2 only, the rotating vector system was made active. Ambient and skin temperatures were measured concomitantly. Repeated-measures ANOVA showed a significant difference between groups (P=0.0361) and over time (P=0.0001) for blood flow data; one-factor ANOVA showed a significant increase in blood flow in the IFT 3 group (10-20 Hz) when compared to all experimental groups at 12 min (P=0.0156). In addition, at 21 min, there were significant differences between the IFT 3 group and all other groups except control (P=0.0213). Statistical analysis of skin temperature data demonstrated significant differences over time (P=0.0001) and a significant interactive effect (P=0.0022), with no significant differences observed between groups. These findings provide some evidence of a putative vasodilatory effect caused by interferential current therapy when applied through suction electrodes at a modulated frequency of 10-20 Hz.

Salmonellosis in North Thames (East), UK: associated risk factors.

We assessed the rate of salmonella infections and risk factors associated with infection in North East Thames in 1993. Cases of culture confirmed infection were identified through microbiology laboratories and environmental health officers in the North East Thames. A total of 1730 cases were reported and 209 of these individuals (those who could be contacted within a 3-week interval after onset of symptoms) and matched controls were interviewed by telephone. In addition randomly selected controls were interviewed over a 4-month period about recent gastric acid lowering medication and antimicrobial ingestion. Sixty-six serotypes were identified: S. enteritidis was isolated from 1179 (69%) cases, S. typhimurium from 221 (13%), S. virchow from 77 (4%) and S. newport 25 (1%). Infections were more frequent in summer months. Highest rates were documented in children under 2 years of age for S. enteritidis (108/100,000) and under 1 year for S. typhimurium (36/100,000). Using the Townsend score, highest isolation rates of S. enteritidis were in more prosperous areas (36/100,000 vs. 27/100,000; odds ratio (OR) 1.3, 95% confidence intervals (CIs) 1.2-1.6, P < 0.0001), while for S. typhimurium, there was no relation between deprivation index and isolation rates areas (6.4/100,000 vs. 6.1/100,000; OR 1.1, 95% CIs 0.8-1.5, P = 0.77). The case control study showed a significant association between ingestion of products containing raw eggs and S. enteritidis infection (8/111 cases vs. 0/110 controls; OR undefined, lower 95% CIs 3.4). Individuals with salmonella infection were significantly more likely to have travelled abroad in the week before the onset of illness [42/186 (23%) vs. 1/182 (0.5%); OR 40, 95% CIs = 5.5-291, P < 0.001] and to report gastroduodenal disease [11/143 (7%) vs. 3/143 (2%); OR 5.0, 95% CIs = 1.1-23, P = 0.04]. There was an association between illness and gastric acid-lowering medications [unmatched controls OR 22.3 (95% CIs 1.5-3.7, P = 0.0002), matched controls OR 3.7 (95% CIs 1.0-3.8, P = 0.07)], but no association with antimicrobial ingestion.

Inhalation toxicity of hexafluoroisobutylene.

An acute study of hexafluoroisobutylene (HFIB) determined its 4-hr LC50 in rats to be 1425 ppm. In a 2-week study, all animals exposed to 215 ppm for 4 days died or were sacrificed in extremis, while those exposed to the lowest level tested, 53 ppm, showed respiratory and renal effects. Based on the results of these studies, Fischer-344 rats were exposed 6 hr a day, 5 days a week, for 13 weeks to average HFIB concentrations of 3, 10, 30, and 90 ppm. No animals died due to the HFIB exposures. However, at the highest exposure level tested there were numerous marked signs of systemic toxicity in males and females. At all exposure levels, males were more affected than females. The lungs and kidneys were clearly target organs for HFIB, the kidneys being more sensitive in this study (having increased absolute and relative weights, alterations in relevant clinical chemistry parameters, and alterations in microscopic structure). A clear dose-response pattern for the above toxic effects was evident with 10 ppm in the males being an effect level. Male rats exposed to 30 ppm of HFIB had decreased body weights and significantly increased kidney weights. A satellite group of animals was maintained for 2 weeks after the completion of exposure. These animals showed some remission from the observed toxic effects, indicating recovery could be expected in rats from at least most of the toxic effects associated with exposure to HFIB. All effects observed in 3 ppm males disappeared by the end of the recovery period.

Innovative designs and practices for acute systemic toxicity studies.

Over a four year period our laboratory has conducted 124 acute systemic toxicity studies (64 oral, 39 dermal, and 21 inhalation), altering study and program designs with the objectives of maximizing information while minimizing animal usage. By employing dose selection strategies, probes, lethality limits instead of LD50's, staggered sequential dosing, and by conducting studies in batteries, animal usage was reduced by 48% below the average number currently quoted as necessary for an LD50 study. Simultaneously, use of a neurobehavioral screen, adjunct studies and a flexible study design have led to a significant upgrading in the information generated by these studies. Additionally, the use of a decision tree approach for selecting tissues for histopathology was developed. The use of specific indicators (such as organ weights) for selecting organs for microscopic examination was also evaluated. Our efforts demonstrate that significantly more information can be generated by studies utilizing fewer animals than is now common practice.