Perception versus Reality: The Relationship between Subjective and Objective Measures of Sleep When On-call under Simulated Laboratory Conditions.

BACKGROUND: On-call working arrangements have been shown to negatively impact sleep. However, workers may perceive their sleep to be worse than it actually is. The aim of this study was to compare participants' pre- and post-sleep estimates of sleep duration and sleep quality with objectively measured sleep when on-call under laboratory conditions. PARTICIPANTS: 72 healthy, adult males. METHODS: Analyses were performed on three interrelated studies, all of which consisted of four nights in a sleep laboratory. Following adaptation and baseline nights were two on-call nights (sleep opportunity 23:00 h - 07:00 h). Before and after each sleep opportunity, participants provided subjective estimates of sleep. Sleep was objectively measured using polysomnography. RESULTS: Estimated sleep duration (6.74 ± 1.13 h) and sleep onset latency (20.55 ± 14.85 min) were significantly poorer than objectively measured sleep outcomes (sleep duration 7.21 ± 1.25 h; sleep latency 13.20 ± 10.06 min). Of the variance in post-sleep estimated sleep duration, 14% was associated with objectively measured minutes of N3 (R2Δ = 0.55) and REM (R2Δ = 0.75). Additionally, 14% of post-sleep sleep quality estimation variance was associated with minutes of N2 (R2Δ = 0.60) and N3 (R2Δ = 0.79), measured by polysomnography. CONCLUSIONS: Some objective measures of sleep were associated with subjective estimates of sleep duration and sleep quality. However, individuals may overestimate sleep onset latency and underestimate sleep duration during on-call periods. It may be beneficial for on-call workers to actively reflect on feelings of fatigue/alertness for workplace fatigue management, rather than relying solely on estimates of sleep.

Waking qEEG to assess psychophysiological stress and alertness during simulated on-call conditions.

INTRODUCTION: On-call schedules are associated with stress and disrupted sleep. In a recent study, under non-sleep deprived conditions, low and high-stress on-call conditions did not significantly impact sleep quality but did impact next day performance. Our aim was to determine whether quantitative electroencephalography (qEEG) would reflect changes in cortical activity in on-call conditions, predicting that the high-stress condition would display faster qEEG frequencies compared with the control and low-stress condition. METHODS: Twenty-four healthy male participants (age: 26.5 ±â€¯4.0 yrs) spent four nights in a time-isolated sleep laboratory. The within-subjects, repeated measures experimental design assessed waking EEG, via the Karolinska Drowsiness Test (KDT) during four time-points across a control day and two experimental (on-call) days. Experimental days comprised a low-stress (LS - reading task) and high-stress (HS - speech task) condition and were counterbalanced. Mixed-models analysis was used to assess condition and time by EEG biomarkers: Alpha Attenuation Coefficient (AAC), Slowing Ratio (SR) and Scaling Exponent (SE). RESULTS: Main effects were found for all three biomarkers by condition, with pairwise analysis reported. There was a significant difference in AAC between the LS condition (M = 1.26 ±â€¯=1.24) and HS condition (M = 1.01 ±â€¯0.76 p = .02) indicating decreased alertness between LS and HS. A significant increase in SR between control (M = 7.1 ±â€¯4.3) and LS (M = 10.1 ±â€¯8.5 p = .0001), and a significant increase between the LS and HS (M = 7.8 ±â€¯6.8 p = .018) showing greatest EEG slowing in the LS condition, reflecting of a passive, sleepier brain state. The SE was significantly higher in the LS (M = 1.09, ±0.17) condition compared with control (M = 1.0, ±0.11 p = .001) indicating decreased alertness in the LS task. DISCUSSION: Using qEEG biomarkers, in contrast with our initial hypothesis, the current study found that compared with control, the LS condition resulted in greater EEG slowing. These findings have implications for on-call workers who engage in periods of passive attention and highlight a protective role task stress may play in maintaining alertness levels during on-call conditions.

"Awake, smoky, and hot": providing an evidence-base for managing the risks associated with occupational stressors encountered by wildland firefighters.

To curtail the spread of wildfire, firefighters are often required to work long hours in hot, smoky conditions with little rest between consecutive shifts. In isolation, heat, smoke, and sleep disruption can have a detrimental impact on cognitive and physical abilities. Far less is known, however, about the combined impact that heat, smoke, and sleep disruption can have on firefighters' performance during wildfire suppression or on human performance in general. The available literature, though scant, suggests that audio and visual tracking may be degraded after sustained heat exposure following one night of sleep deprivation. Exposure to heat and carbon monoxide, in contrast, appears to have only limited impact on cognitive performance, even after physical exercise. Heat and carbon monoxide exposure does, however, increase physiological exertion to a given work or exercise bout. To the authors' knowledge, there are no published studies that have explored the impacts of heat exposure following sleep disruption on physical work performance, sleep disruption and smoke exposure on physical or cognitive work, or the combined impacts of sleep disruption, smoke and heat exposure on cognitive or physical work. While more integrative research is needed, the current review provides a summary of the available evidence and an indication of the degree of confidence agencies can have in the research. This will allow both the scientific community and agencies to make informed recommendations regarding the management of wildland firefighters' health and safety on the fireground.

Changes in structural aspects of mood during 39-66 h of sleep loss using matched controls.

A number of studies have described mood change during sleep loss in the laboratory, however, an understanding of fluctuations in structural aspects of mood under such conditions is lacking. Sixty-two healthy young adults completed one of three possible conditions: one (n = 20) or two (n = 23) nights of sleep loss or the control condition which consisted of one (n = 9) or two (n = 10) nights of 9 h time in bed. The Mood Scale II was completed every two waking hours and data were analysed in terms of the frequency and intensity of mood reports. Overall, sleep loss conditions were associated with significantly less frequent happiness and activation and more frequent fatigue reports (p < 0.001). Intensity was also significantly reduced for activation and happiness, and increased for depression, anger and fatigue (p < 0.05). Interestingly, there were no significant differences in anger following two nights in the laboratory with or without sleep. Further, two nights in the lab with normal sleep was associated with significant increases in depression intensity (p < 0.05). Findings support the hypothesis of a mood regulatory function of sleep and highlight the relative independence of frequency and intensity and of positive and negative mood dimensions. Findings also suggest that the laboratory environment, in the absence of sleep loss, may have a significant negative impact on mood.

Serum levels of albumin, triglycerides, total protein and glucose in rats are altered after oral treatment with low doses of 13-cis-retinoic acid or all-trans-retinoic acid.

Currently used to treat severe acne, 13-cis-retinoic acid (13-cis-RA) is under investigation for its anticancer effects as is the isomer, all-trans-retinoic acid (all-trans-RA). Here, the effects of oral 13-cis-RA or all-trans-RA treatment on serum chemistry, leptin and adiponectin levels were evaluated. Adult Sprague-Dawley rats were gavaged once daily for 7 consecutive days with 13-cis-RA (7.5 or 15 mg kg(-1)), all-trans-RA (10 or 15 mg kg(-1)) (n=24/sex/dose), or soy oil (n=16/sex) and blood was sampled 30-480 min after the last gavage. The body weight was unaffected; however, the liver/body weight ratios were increased by both doses of all-trans-RA. Sex differences were noted for levels of cholesterol, creatine, triglycerides, albumin, alanine aminotransferase and total protein. Both doses of all-trans-RA reduced albumin levels to approximately 90% of the control and total protein levels to approximately 93% of the control while substantially elevating triglyceride levels to approximately 66%-99% above the control. Additionally, triglyceride levels of the 15 mg kg(-1) 13-cis RA group were approximately 62% higher than the controls and total protein levels were approximately 5% less. Glucose levels were affected by sex and RA treatment in that males treated with 15 mg kg(-1) of 13-cis-RA or 10 mg kg(-1) all-trans-RA had lower (13%-19%) levels than the same-sex controls; however, females were not similarly affected. Neither 13-cis-RA nor all-trans-RA treatment had significant effects on the levels of blood urea nitrogen, aspartate amino transferase, leptin or adiponectin. On a mg kg(-1) basis, all-trans-RA was more potent than 13-cis-RA. These results replicate previous findings of RA-induced increased triglyceride levels. Additionally, several new findings indicate there may be sex-specific effects of RA treatment. Finally, neither treatment appeared to alter the typical diurnal cycles of these endpoints.

Long term dietary methoxychlor exposure in rats increases sodium solution consumption but has few effects on other sexually dimorphic behaviors.

Methoxychlor is an insecticide with estrogen-like activity, thus exposure during development might cause sexually dimorphic behavioral alterations. To evaluate this, pregnant rats consumed diets containing 0, 10, 100 or 1000 ppm methoxychlor from gestational day 7, and offspring continued on these diets until postnatal day (PND) 77. Assessments of sexually dimorphic behaviors in offspring indicated that intake of a 3.0% sodium chloride solution was significantly increased (41%) in males and females of the 1000 ppm group. No treatment group differed from controls in open field nor running wheel activity, play behavior, nor 0.3% saccharin solution intake. Offspring of the 1000 ppm group showed significantly decreased body weight, reaching 17% less than controls at PND 77, but not clearly related to their salt solution intake. During pregnancy, 1000 ppm dams consumed 23% less food and weighed 10% less than controls, but this did not affect litter outcomes. These results indicate that in rodents, developmental and chronic exposure to dietary methoxychlor alters the sexually dimorphic behavior of salt-solution intake in young adults of both sexes. Similar behavioral alterations with other xenoestrogens, and the potential for interactions among xenoestrogens, suggest that this report may minimize the true effects of dietary methoxychlor exposure.

Validity and reliability of sincerity test for dynamic trunk motions.

PURPOSE: Marras et al. developed a technique to evaluate sincerity of effort during dynamic trunk motion performance. The validity and reliability of the technique have not been evaluated. Therefore, the objective of this study was to first determine whether or not a sincerity of effort measure correctly identified those giving a sincere effort in a blinded randomized control trial and second to quantify inter-rater and test-retest reliability. METHODS: This article reports the findings of a two phase study. In phase one, the blinded evaluation, participants were randomly assigned to either a sincere or insincere performance condition. An examiner tested participants without knowledge of the participant's group membership. In the second phase, two examiners evaluated each participant twice to quantify inter-rater and test-retest reliability. RESULTS: In the blinded phase the specificity was 100% and sensitivity was 90% for identifying sincere and insincere effort, respectively. Phase two results showed no significant difference in probability of sincere effort between raters or between testing sessions. CONCLUSION: A performance criterion that accurately identifies sincere vs insincere group membership during functional evaluations was identified. There were no significant differences between raters or between testing sessions. These findings indicate that this test is reliable and possesses good predictive validity in assessing sincerity of effort.

The impact of roster changes on absenteeism and incident frequency in an Australian coal mine.

BACKGROUND: The occupational health and safety implications associated with compressed and extended work periods have not been fully explored in the mining sector. AIMS: To examine the impact on employee health and safety of changes to the roster system in an Australian coal mine. METHODS: Absenteeism and incident frequency rate data were collected over a 33 month period that covered three different roster schedules. Period 1 covered the original 8-hour/7-day roster. Period 2 covered a 12-month period under a 12-hour/7-day schedule, and period 3 covered a 12-month period during which a roster that scheduled shifts only on weekdays, with uncapped overtime on weekends and days off (12-hour/5-day) was in place. Data were collected and analysed from the maintenance, mining, and coal preparation plant (CPP) sectors. RESULTS: The only significant change in absenteeism rates was an increase in the maintenance sector in the third data collection period. Absenteeism rates in the mining and CPP sectors were not different between data collection periods. The increase in the maintenance sector may be owing to: (1) a greater requirement for maintenance employees to perform overtime as a result of the roster change compared to other employee groups; or (2) greater monotony associated with extended work periods for maintenance employees compared to others. After the first roster change, accident incident frequency decreased in the CPP sector but not in the other sectors. There was no effect on incident frequency after the second roster change in any sector. CONCLUSIONS: The current study did not find significant negative effects of a 12-hour pattern, when compared to an 8-hour system. However, when unregulated and excessive overtime was introduced as part of the 12-hour/5-day roster, absenteeism rates were increased in the maintenance sector. The combination of excessive work hours and lack of consultation with employees regarding the second change may have contributed to the overall negative effects.

Rationale for graduated licensing and the risks it should address.

The increased crash risk of young, beginning drivers has long been cause for concern. Graduated licensing systems, which seek to phase in driving experience gradually over time, have recently been adopted by many states in an effort to reduce these risks. In an attempt to define the basic rationale for graduated licensing, relevant research evidence that describes the conditions under which risk is known to be increased for young drivers was reviewed. Potential changes in licensing laws that best address these known risk factors are described. It was found that certain situations contribute to even greater crash risk, most notably nighttime driving and driving with passengers in the peer group. The underlying premise for graduated licensing is that while crash risk of young drivers is heightened under all situations, some situations are more or less risky than others. If experience can be gained initially under lower risk conditions, both in the learning stage and when first licensed, crash risk will be reduced.

Older driver involvements in police reported crashes and fatal crashes: trends and projections.

OBJECTIVES: Older drivers have become a larger part of the driving population and will continue to do so as the baby boomers reach retirement age. The purpose of this study was to identify the potential effects of this population increase on highway safety. METHODS: Driver involvement rates for all police reported crashes were calculated per capita, per licensed driver, and per vehicle-mile of travel for 1990 and 1995. Also, driver involvement rates for fatal crashes were calculated for 1983, 1990, and 1995. Based on current crash rates per licensed driver and estimates of the future number of licensed drivers, projections of crashes involving drivers aged 65 and older were made for years 2010, 2020, and 2030. RESULTS: Driver crash involvement rates per capita decreased with age, but fatal involvement rates per capita increased starting at age 70. The same pattern existed for involvement rates per licensed driver. For both all crashes and fatal crashes, involvement rates per mile driven increased appreciably at age 70. Using projections of population growth, it was estimated that for all ages there will be a 34% increase in the number of drivers involved in police reported crashes and a 39% increase in the number involved in fatal crashes between 1999 and 2030. In contrast, among older drivers, police reported crash involvements are expected to increase by 178% and fatal involvements may increase by 155% by 2030. Drivers aged 65 and older will account for more than half of the total increase in fatal crashes and about 40% of the expected increase in all crash involvements; they are expected to account for as much as 25% of total driver fatalities in 2030, compared with 14% presently. CONCLUSIONS: By most measures, older drivers are at less risk of being involved in police reported crashes but at higher risk of being in fatal crashes. Although any projections of future crash counts have inherent uncertainty, there is strong evidence that older drivers will make up a substantially larger proportion of drivers involved in fatal crashes by 2030 because of future increases in the proportion of the population aged 65 and older, and trends toward increased licensure rates and higher annual mileage among older persons. Countermeasures to reduce the anticipated death toll among older drivers should address the increased susceptibility to injury of older vehicle occupants in crashes.

Spinal loading when lifting from industrial storage bins.

The study documented three-dimensional spinal loading during lifting from an industrial bin. Two lifting styles and two bin design factors were examined in Phase I. The lifting style measures in Phase I were one hand versus two hand and standing on one foot versus two feet. The bin design variables were region of load in the bin and bin height. The Phase II study examined one-handed lifting styles with and without supporting body weight with the free hand on the bin as well as region and the number of feet. Twelve male and 12 female subjects lifted an 11.3 kg box from the bin. Spinal compression, lateral shear and anterior - posterior shear forces were estimated using a validated EMG-assisted biomechanical model. Phase I results indicated that the bin design factor of region had the greatest impact on spinal loading. The upper front region minimized spinal loading for all lifting styles. Furthermore, the lifting style of two hands and two feet minimized spinal loading. However, comparing Phase I two-handed lifting with Phase II one-handed supported lifting, the one-handed supported lifting techniques had lower compressive and anterior - posterior shear loads in the lower regions as well as the upper back region of the bin. A bin design that facilitates lifting from the upper front region of the bin reduces spinal loading more effectively than specific lifting styles. Furthermore, a bin design with a hand hold may facilitate workers using a supported lifting style that reduces spinal loading.

No alterations in the performance of two interval timing operant tasks after alpha-difluoromethylornithine (DFMO)-induced cerebellar stunting.

The cerebellum is critically involved in temporal processes in the millisecond range and may be involved in longer time estimations (i.e. in the seconds range). Estimates in the millisecond range are impaired after developmentally induced cerebellar alterations, however, little is known about the effects of similar alterations on longer timing performance. Appropriately timed DFMO treatment reliably causes cerebellar stunting in rats, however, its effects on temporal estimation performance are unknown. Here, male and female Sprague-Dawley rats were treated with subcutaneous injections of 500 mg/kg DFMO on postnatal days 5-12, causing a 10% cerebellar weight reduction at adulthood. As adults, subjects were tested under one of two paradigms - a differential reinforcement of low response rate (DRL) task requiring that subjects withhold a lever press response for 10-14 s or a temporal response differentiation (TRD) task requiring that subjects maintain a lever press response for 10-14 s. Training and steady-state performance of the DRL and TRD tasks were not significantly altered by DFMO treatment. Performance after acute challenges with two dopaminergic agonists (2.00-7.50 mg/kg methylphenidate and 0.10-1.00 mg/kg d-amphetamine) was measured after which all subjects underwent behavioral extinction. Generally, performance after methylphenidate and d-amphetamine was similar in control and DFMO-treated rats and DFMO treatment had no differential effects on performance during extinction. These results support findings from an earlier study [Ferguson SA, Paule MG, Holson RR. Neonatal dexamethasoneon day 7 in rats causes behavioral alterations reflective of hippocampal, but not cerebellar, deficits. Neurotoxicol Teratol, 2001; 23:57-69] indicating that developmental cerebellar stunting has few effects on time estimation within the range of seconds.

L-ephedrine-induced neurodegeneration in the parietal cortex and thalamus of the rat is dependent on hyperthermia and can be altered by the process of in vivo brain microdialysis.

Multiple doses of the dietary supplement L-ephedrine can cause severe hyperthermia and modest dopamine depletions in the rat brain. Since D-amphetamine treatment can result in neurodegeneration, the potential of L-ephedrine to produce similar types of degeneration was investigated. Adult male rats, some implanted in the caudate/putamen (CPu) for microdialysis, were given four doses of 25 mg/kg L-ephedrine or 5 mg/kg D-amphetamine (2 h between doses) at an ambient temperature of 23 degrees C. L-ephedrine-induced degeneration in the forebrain was dependent on the degree of hyperthermia. Layer IV of the parietal cortex was the most sensitive to L-ephedrine treatment with peak body temperatures of at most 40.0 degrees C necessary to produce degeneration. Extensive neurodegeneration in the parietal cortex after L-ephedrine treatment was as pronounced as that previously described for D-amphetamine treatment and also occurred in the intralaminar, ventromedial and ventrolateral thalamic nuclei in rats with severe hyperthermia (peak body temperatures>41.0 degrees C). The neurodegeneration induced by L-ephedrine may have resulted in part from excitotoxic mechanisms involving the indirect pathways of the basal ganglia and related areas. No differences were observed between microdialysis and non-implanted rats with respect to degree of tyrosine hydroxylase (TH) loss in the CPu after either D-amphetamine or L-ephedrine treatment. However, neurodegeneration resulting from D-amphetamine and L-ephedrine was reduced in the microdialysis animals in the hemisphere ipsilateral to the probe, which raises concerns when using the technique of in vivo microdialysis to evaluate neurodegeneration. The results of this study, in conjunction with human clinical evaluation of ephedrine neurotoxicity, indicate that regionally specific damage may occur in the cortex of some humans exposed to ephedrine in the absence of stroke or hemorrhage.

Spine loading characteristics of patients with low back pain compared with asymptomatic individuals.

STUDY DESIGN: Patients with low back pain and asymptomatic individuals were evaluated while performing controlled and free-dynamic lifting tasks in a laboratory setting. OBJECTIVE: To evaluate how low back pain influences spine loading during lifting tasks. SUMMARY OF BACKGROUND DATA: An important, yet unresolved, issue associated with low back pain is whether patients with low back pain experience spine loading that differs from that of individuals who are asymptomatic for low back pain. This is important to understand because excessive spine loading is suspected of accelerating disc degeneration in those whose spines are damaged already. METHODS: In this study, 22 patients with low back pain and 22 asymptomatic individuals performed controlled and free-dynamic exertions. Trunk muscle activity, trunk kinematics, and trunk kinetics were used to evaluate three- dimensional spine loading using an electromyography- assisted model in conjunction with a new electromyographic calibration procedure. RESULTS: Patients with low back pain experienced 26% greater spine compression and 75% greater lateral shear (normalized to moment) than the asymptomatic group during the controlled exertions. The increased spine loading resulted from muscle coactivation. When permitted to move freely, the patients with low back pain compensated kinematically in an attempt to minimize external moment exposure. Increased muscle coactivation and greater body mass resulted in significantly increased absolute spine loading for the patients with low back pain, especially when lifting from low vertical heights. CONCLUSIONS: The findings suggest a significant mechanical spine loading cost is associated with low back pain resulting from trunk muscle coactivation. This loading is further exacerbated by the increases in body weight that often accompany low back pain. Patient weight control and proper workplace design can minimize the additional spine loading associated with low back pain.

Gender-based differences in rats after chronic dietary exposure to genistein.

Gender-based differences can be observed from pharmacokinetic, behavioral, or anatomical assessments. No single assessment tool will provide a complete answer, but the use of a variety of indices, each with known gender-related outcome differences, can reveal agent-induced gender-based alterations. In a series of initial range-finding studies in rats conducted at the National Center for Toxicological Research (NCTR), the effects of dietary exposure to the weak estrogen, genistein, have been assessed using a number of techniques with validated gender-related outcome measures. The findings indicated that (1) the internal dose of genistein was higher in females than males after equivalent dietary exposure and this was consistent with the faster rate of genistein elimination in males; (2) in behavioral assessments, males and females in the high-dose dietary genistein group consumed more of a sodium-flavored solution; however, no genistein-related changes were observed in open field or running wheel activity, play behavior, or intake of a saccharin-flavored solution; and (3) dose-related alterations of the volume of the sexually dimorphic nucleus of the medial preoptic area were observed in genistein-exposed male rats but not females. These observations describe the utility of a variety of gender-based assessment tools and indicate that dose-related effects of developmental and chronic dietary exposure to genistein can be observed in the rodent. Additional studies, perhaps in nonhuman primates, are necessary to further predict the effect(s) of genistein on human gender-based development.

Perceptions of labour pain by mothers and their attending midwives.

AIMS: The aim of the current study was to examine the perception of pain by labouring women and their attendant midwife, from the onset of labour to delivery. RATIONALE: Accurate measurement and appropriate management of pain is a significant problem for attendant medical and nursing personnel. Both the experience and perception of pain are regarded as subjective and are therefore difficult to measure objectively. Indeed, much of the literature reports that pain is often under- or over-estimated by nursing staff who as a consequence consistently fail to administer adequate analgesia. Few studies have specifically examined the ability of midwives to assess the pain of labouring women. DESIGN: The short form McGill Pain Questionnaire (SF-MPQ), routinely used to assess pain in obstetric environments, was used to determine pain perception. Thirteen labouring women and nine midwives completed the SF-MPQ every 15 minutes beginning at the time of admittance to the delivery suite. Peak pain ratings for the preceding 15 minutes were obtained without reference to prior ratings or each other's scores. Further, midwives in the maternity unit of The Queen Elizabeth Hospital (TQEH), Adelaide, South Australia completed a survey investigating the cues they use to assess pain during labour. RESULTS: On each measure of pain on the SF-MPQ, the midwives scores correlated with the mothers' scores across the entire pain range. Further analysis showed that mothers' and midwives' pain scores were similar at mild-moderate pain levels, but midwives significantly underestimated pain intensity at levels that mothers described as severe. The survey responses indicated that midwives rely on both verbal and nonverbal cues to assess pain levels. CONCLUSIONS: The cues used by midwives to differentiate pain intensities and qualities are similar to those used in other clinical settings, but may have limited discriminatory value as pain levels become severe.

Behavioral responses of rats exposed to long-term dietary vinclozolin.

Vinclozolin is a fungicide used on food crops with human exposure estimated at approximately 2 microg/kg/day from ingestion; occupational exposure, however, may be greater. The metabolites of vinclozolin have been reported to act as antiandrogens and have adverse effects on reproductive physiology and behavior in animals. Here, pregnant rats were fed soy-free diets containing 0, 10, 150, or 750 ppm of vinclozolin (approximately 0, 0.8, 12, and 60 mg/kg/day for an adult) beginning on gestational day 7, and offspring were continued on these diets through sacrifice at postnatal day 77. Male and female offspring were assessed for changes in several nonreproductive sexually dimorphic behaviors: open field and running wheel locomotor activity, play behavior, and consumption of saccharin- and sodium chloride-flavored solutions. There was a significant interaction of sex with vinclozolin exposure on running wheel activity, which indicated that females in the high-dose exposure group were hypoactive compared to same-sex controls. There was a significant overall effect of vinclozolin exposure on fluid consumption, and high-dose animals showed increased intake of the saccharin solution and decreased intake of plain water while saccharin was available. Effects were more pronounced in females, which drank 40.8% more saccharin than control females, whereas males drank 6.2% more than control males. There were no effects of vinclozolin treatment on play behavior or sodium solution intake. Gestational duration, total and live pups per litter, litter sex ratios, and birth weight were also not significantly affected, nor were body weight and food intake for dams and offspring. These results indicate that long-term dietary exposure to vinclozolin does not have severe toxicological consequences on the nonreproductive behaviors measured here. However, exposure may cause subtle alterations in locomotor activity and consumption of saccharin-flavored solution.

Localized oxygen use of healthy and low back pain individuals during controlled trunk movements.

Individuals who have low back pain (LBP) have significantly different motion characteristics than healthy individuals. However, the cause of these differences is unknown. Oxygen use of the erector spinae muscle was examined while simultaneously monitoring motion characteristics to determine whether oxygen use differed between healthy and LBP individuals. Thirty volunteers were classified as healthy, structural, or muscular-based LBP. A near-infrared spectrometer monitored oxygen use and blood volume in the lumbar region. Results showed significant differences in oxygen use but not blood volume between healthy and LBP subjects with muscular-based disorders. Inability of the muscular group to use oxygen in a manner similar to the healthy group indicates different processes at the tissue level, indicating that differences in oxygen use may provide insight into why motion patterns differ between healthy and LBP groups.