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Tumor hypoxia is a hallmark of malignant tumors, and is a major factor in the resistance to anti-cancer therapies, particularly radiotherapy. Indeed, tumor blood flow often fluctuates, and thus the oxygen supply is often reduced, thereby inducing tumor hypoxia. We decided to explore whether post-occlusive reactive hyperemia, a physiological reaction known to occur in normal tissues, could be induced through a malignant tumor, basal cell carcinoma (BCC), in which angiogenesis occurs, as in all malignant tumors. Skin blood flow was measured in twelve patients with BCC, using Laser Speckle Contrast Imaging to determine BCC perfusion after three minutes of vascular occlusion, induced by limb tourniquet for limb tumors (4 BCC), and/or by clamping the pedicle of a skin flap with the BCC at its center, for other tumor locations (12 BCC). We demonstrated for the first time that post-occlusive reactive hyperemia occurs in malignant tumors in humans. BCC perfusion curves were similar to those of healthy skin, characterized by a peak of hyperemia after reperfusion followed by a progressive return to the pre-occlusion perfusion level. Induction of post-occlusive reactive hyperemia in malignant tumors is therefore a novel investigational approach that could lead to a new adjuvant tool to increase the efficacy of chemotherapy and radiotherapy, respectively through the synchronized temporary increase of tumor perfusion and oxygenation. [ABSTRACT FROM AUTHOR]

BackgroundNeuropsychological impairment is a key feature of late-life depression, with deficits observed across multiple domains. However, it is unclear whether deficits in multiple domains represent relatively independent processes with specific neural correlates or whether they can be explained by cognitive deficits in executive function or processing speed.MethodWe examined group differences across five domains (episodic memory; executive function; language skills; processing speed; visuospatial skills) in a sample of 36 depressed participants and 25 control participants, all aged ⩾60 years. The influence of executive function and processing speed deficits on other neuropsychological domains was also investigated. Magnetic resonance imaging correlates of executive function, processing speed and episodic memory were explored in the late-life depression group.ResultsRelative to controls, the late-life depression group performed significantly worse in the domains of executive function, processing speed, episodic memory and language skills. Impairments in executive function or processing speed were sufficient to explain differences in episodic memory and language skills. Executive function was correlated with anisotropy of the anterior thalamic radiation and uncinate fasciculus; processing speed was correlated with anisotropy of genu of the corpus callosum. Episodic memory was correlated with anisotropy of the anterior thalamic radiation, the genu and body of the corpus callosum and the fornix.ConclusionsExecutive function and processing speed appear to represent important cognitive deficits in late-life depression, which contribute to deficits in other domains, and are related to reductions in anisotropy in frontal tracts. [ABSTRACT FROM PUBLISHER]

The article focuses on the promotion of school-based physical activity (PA) for youth in the U.S. It describes the schools' leadership role in improving the health and PA levels of youth and the several legislations that require the schools to receive federal grants. It discusses the role of physical educators in the promotion of school-based PA and describes the quality physical education (QPE). It also discusses the school day's segments that show the potential for improving school-based PA.

This paper presents findings from a six-year research programme underway in New Zealand to develop strategies for improving the resilience of organisations to major crisis events. The research takes a systems view of organisations, recognising that there are multiple interdependencies within and between different organisations that influence their abilities to respond and recover. This means that effective resilience management for any one organisation must look beyond that single organisation and consider the resilience of other organisations on which it depends. Particular aspects of organisational resilience focused on by the research team include: how individual organisations are positioned to respond to and recover from major crises; their ability to communicate and share information in order to direct resources effectively during crises; and the legal and contractual frameworks within which they will need to operate during crisis response and recovery. None of these issues can be resolved by a single organisation acting unilaterally. Organisations are required to work together towards greater system resilience. [ABSTRACT FROM AUTHOR]

Background. Biases in the processing of emotional information have been shown to be abnormal in subjects with major depression, both during an episode and after full recovery. However, it is unclear whether these biases are a cause or an effect of the depression. This study set out to explore whether such biases represent a vulnerability factor for depression by looking at unaffected first-degree relatives of those with major depressive disorder. We also measured waking salivary cortisol, as the regulation of the hypothalamo–pituitary–adrenal (HPA) axis is thought to be impaired in depressive disorder.Method. Twenty-five female relatives and 21 age-matched controls completed a facial expression recognition task, an emotional categorization task with positive and negative personality characteristics, and had their waking salivary cortisol measured on a work day and a non-work day.Results. The depressed relative group was significantly faster to recognize facial expressions of fear than controls. The depressed relative group also showed significantly increased reaction time to recognize positive versus negative personality characteristics in the categorization task. There was no difference in waking salivary cortisol between groups, although there was an effect of work day versus non-work day.Conclusions. Subtle biases in the processing of emotional information may exist in the unaffected first-degree relatives of those with depression. As such, this may represent a familial vulnerability factor to developing a depressive illness. [ABSTRACT FROM AUTHOR]

The article focuses on the importance of youth motivations in physical education and physical activity in the U.S. The author shared perspectives, philosophies and trends in physical education and youth participation in physical activity. According to the author, physical educators fill important roles in children's physical activity experiennces as instructors, role model and mentors. Meanwhile , physical education provides children with many opportunities to gauge their ability and has manly benefits of perceived competence have been identified.

The purpose of this study was to examine if steps/day taken by middle school students varied based on aerobic fitness classification. Middle school students (N = 223; 112 girls, 111 boys) were assigned to three aerobic fitness categories (HIGH, MOD, LOW) based on results of the FITNESSGRAM PACER test. Four weekdays of pedometer monitoring determined activity levels (steps/day). Boys accumulated significantly more steps/day than girls, 11,589 ± 3, 270 and 10,232 ± 2, 517 steps/day, respectively; F (1, 219) = 16.0, p < .001, η² = .055. There were no differences in steps/day between grades. HIGH fit participants accumulated significantly more steps/day, F (2, 217) = 12.2, p < .001, η² =.101, than moderately fit and low fit participants (≈ 1,491 and ≈ 2, 867 steps/day, respectively). Middle school students who participated in sports in addition to physical education (PE) accumulated significantly more steps/day (≈ 980 steps/day) than those participating in PE only, F(1, 219) = 10.0, p < .01, η² = .044. Although the relationship between physical activity and aerobic fitness was moderate (0.35; p < .01), these data demonstrated significant differences in accumulated steps/day among youth of varying aerobic fitness levels. Whether improved fitness levels were the result of additional activity or the cause of it remains to be determined. Regardless, the fittest middle school students were also the most active and accumulated a significant amount of steps/day through organized extracurricular physical activities. [ABSTRACT FROM AUTHOR]

Central dopamine function is reduced by decreasing the availability of the catecholamine precursor, tyrosine, using a tyrosine-free amino acid mixture containing multiple large neutral as well as branched chain amino-acids, which compete with tyrosine for uptake into the brain. Current mixtures are cumbersome to make and administer, and unpalatable to patients and volunteers. Here, we investigate whether individual or limited amino-acid combinations could reduce brain tyrosine levels and hence dopamine function. Measurements of regional brain tyrosine levels, catecholamine and indoleamine synthesis (L-DOPA and 5-HTP accumulation, respectively) were used to identify an effective paradigm to test in neurochemical, behavioral and fos immunocytochemical models. Administration of leucine or isoleucine, or a mixture of leucine, isoleucine, and valine reduced tyrosine and 5-HTP, but not L-DOPA accumulation. A mixture of leucine, valine, and isoleucine supplemented with tryptophan reduced brain tyrosine and L-DOPA, but not 5-HTP. In microdialysis experiments this amino-acid mixture reduced basal and amphetamine-evoked striatal dopamine release, as well as amphetamine-induced hyperactivity. This mixture also reduced amphetamine-induced fos expression in striatal areas. In conclusion, the present study identified a small combination of amino acids that reduces brain tyrosine and dopamine function in a manner similar to mixtures of multiple amino acids. This minimal mixture may have use as a dopamine reducing paradigm in patient and volunteer studies.Neuropsychopharmacology (2006) 31, 310–317. doi:10.1038/sj.npp.1300835; published online 20 July 2005 [ABSTRACT FROM AUTHOR]

Presents the results of several physical activity measurement studies on children and youth in the U.S. Transition from physical fitness measurement to physical activity measurement of U.S. youth; Guidelines issued by the National Association for Sport and Physical Education for adolescents aged 13-18; List of Healthy People 2010 objectives related to physical activity and physical education; Information on digital devices used to measure physical activity in children and youth.

PURPOSE: Two studies were conducted to examine the concurrent accuracy of the Yamax SW-200 (YAM), Omron HJ-105 (OM), and Sportline 330 (SL) pedometers, as well as a CSA accelerometer. METHODS: In study 1, motion sensor performance was evaluated against actual (observed) steps taken during 5-min bouts at five different treadmill speeds (54, 67, 80, 94, and 107 m x min) using a two-way repeated measures ANOVA (instrument x speed). Additionally, the direction and magnitude of motion sensor error was examined. In study 2, pedometer performance during 24 h of free-living was evaluated against the steps detected by the CSA criterion. The direction and magnitude of pedometer error was also examined in the free-living condition. RESULTS: In study 1, the SL showed significant differences from actual steps taken at all treadmill speeds (P < 0.05). Further, the absolute value of percent error was greatest for the SL at all treadmill speeds. At the slowest treadmill speed (54 m x min), the absolute value of percent error increased for the YAM and OM. In study 2, only the SL detected fewer steps than the CSA criterion (P < 0.05). The YAM demonstrated the lowest absolute value of percent error under free-living conditions. CONCLUSIONS: Different brands of motion sensors detect steps differently; therefore, caution must be used when comparing step counts between studies that have employed different brands of motion sensors. Taking into consideration the results of both studies and the initial walking test used for instrument screening purposes, it appears that, of the three pedometers tested, the YAM pedometer is most consistently accurate under both controlled and free-living conditions. Future research must consider presenting motion sensor accuracy in absolute terms so that the magnitude of error is not underestimated. [ABSTRACT FROM AUTHOR]

Rationale. Acute depletion of brain tyrosine using a tyrosine-free amino acid mixture offers a nutritional approach to reduce central catecholamine function. Recent preclinical data suggest that tyrosine-free amino acid mixtures may have region-specific effects through targeting dopamine neurones. Objectives. Here we used fos immunocytochemistry to examine the neuroanatomical sites of action of a tyrosine-free amino acid mixture administered either alone or combined with amphetamine. Methods. Rats (male, Sprague Dawley, 240–260 g) were administered (IP) either a tyrosine-free amino acid mixture (1 g/kg), or the same mixture supplemented with tyrosine and phenylalanine (1 g/kg). Mixtures were injected twice (1 h apart) followed 1 h later by amphetamine (2 mg/kg SC). Two hours later, cardiac perfusion was performed and brains were processed for fos immunocytochemistry. Fos positive cells were counted using computer imaging software. Results. The tyrosine-free amino acid mixture alone did not alter fos expression in ten regions of the rat forebrain compared to saline controls. However, the mixture reduced the increase in fos expression evoked by amphetamine. This effect was region-specific and was greatest in caudate putamen, nucleus accumbens, bed nucleus stria terminalis and lateral habenula, and lacking in other areas including cingulate and insular cortices, lateral septum and central amygdaloid nucleus. Moreover, in most regions the effect of the tyrosine-free mixture was less after tyrosine and phenylalanine supplementation. Conclusions. In summary, a tyrosine-free amino acid mixture reduced amphetamine-induced fos expression but this effect was region-specific and included dopamine-rich regions. These data further support the idea that tyrosine depletion strategies have potential as treatments for mania and other hyperdopaminergic states. [ABSTRACT FROM AUTHOR]

Previous neurochemical and behavioural studies show that tyrosine depletion using a nutritionally balanced tyrosine-free amino acid mixture attenuates the dopamine-releasing and psychostimulant properties of amphetamine. Here we investigate the effect of a tyrosine-free amino acid mixture on striatal binding of [11C]raclopride, and amphetamine-induced [11C]raclopride displacement, using positron emission tomography in the rat. Rats were scanned for 60 min after an i.v. injection of ~11 MBq [11C]raclopride using a quad-HIDAC system. Amphetamine (2 mg/kg i.p., 30 min prior to scan) caused a 12% reduction in [11C]raclopride distribution volume ratio (DVR) compared to saline-injected controls. The tyrosine-free amino acid mixture (1 g/kg i.p.) caused a small (+7%) but statistically insignificant increase in [11C]raclopride DVR and attenuated, although it did not fully block, the amphetamine-induced reduction. These data are in keeping with previous neurochemical, immunocytochemical, and behavioural studies showing that tyrosine-free amino acid mixtures reduce dopamine function and offer promise for future PET studies testing the effect of tyrosine-depleting paradigms on dopamine release in humans. Synapse 51:151–157, 2004. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose of this investigation was to compare the concurrent accuracy of the CSA accelerometer and the Yamax pedometer under two conditions: 1) on a treadmill at five different speeds and 2) riding in a motorized vehicle on paved roads. METHODS: In study 1, motion sensor performance was evaluated against actual steps taken during 5-min bouts at five different treadmill walking speeds (54, 67, 80, 94, and 107 m.min-1). In study 2, performance was evaluated during a roundtrip (drive 1 and drive 2) motor vehicle travel on paved roads (total distance traveled was 32.6 km or 20.4 miles). Any steps detected during motor vehicle travel were considered error. RESULTS: In study 1, the Yamax pedometer detected significantly (P < 0.05) fewer steps than actually taken at the slowest treadmill speed (54 m.min-1). Further, the pedometer detected fewer steps than the accelerometer at this speed (75.4% vs 98.9%, P < 0.05). There were no differences between instruments compared with actual steps taken at all other walking speeds. In study 2, the CSA detected approximately 17-fold more erroneous steps than the pedometer (approximately 250 vs 15 steps for the total distance traveled, P < 0.05). CONCLUSIONS: The magnitude of the error (for either instrument) is not likely an important threat to the assessment of free-living ambulatory populations but may be a problem for pedometers when monitoring frail older adults with slow gaits. On the other hand, CSA accelerometers erroneously detect more nonsteps than the Yamax pedometer under typical motor vehicle traveling conditions. This threat to validity is likely only problematic when using the accelerometer to assess physical activity in sedentary individuals who travel extensively by motor vehicle. [ABSTRACT FROM AUTHOR]

LE MASURIER, G. C., and C. TUDOR-LOCKE. Comparison of Pedometer and Accelerometer Accuracy under Controlled Conditions. Med. Sci. Sports Exerc., Vol. 35, No. 5, pp. 867-871, 2003.PURPOSEThe purpose of this investigation was to compare the concurrent accuracy of the CSA accelerometer and the Yamax pedometer under two conditions: 1) on a treadmill at five different speeds and 2) riding in a motorized vehicle on paved roads.METHODSIn study 1, motion sensor performance was evaluated against actual steps taken during 5-min bouts at five different treadmill walking speeds (54, 67, 80, 94, and 107 m·min-1). In study 2, performance was evaluated during a roundtrip (drive 1 and drive 2) motor vehicle travel on paved roads (total distance traveled was 32.6 km or 20.4 miles). Any steps detected during motor vehicle travel were considered error.RESULTSIn study 1, the Yamax pedometer detected significantly (P < 0.05) fewer steps than actually taken at the slowest treadmill speed (54 m·min-1). Further, the pedometer detected fewer steps than the accelerometer at this speed (75.4% vs 98.9%, P < 0.05). There were no differences between instruments compared with actual steps taken at all other walking speeds. In study 2, the CSA detected approximately 17-fold more erroneous steps than the pedometer (approximately 250 vs 15 steps for the total distance traveled, P < 0.05).CONCLUSIONSThe magnitude of the error (for either instrument) is not likely an important threat to the assessment of free-living ambulatory populations but may be a problem for pedometers when monitoring frail older adults with slow gaits. On the other hand, CSA accelerometers erroneously detect more nonsteps than the Yamax pedometer under typical motor vehicle traveling conditions. This threat to validity is likely only problematic when using the accelerometer to assess physical activity in sedentary individuals who travel extensively by motor vehicle. [ABSTRACT FROM AUTHOR]

A pairwise additive potential, which approximately reproduces the free energy density for the elastic deformations of a nematic liquid crystal, originally proposed by Gruhn and Hess, has been investigated by simulating the three Freedericksz transitions as well as that of the Schadt-Helfrich cell. The pair potential depends on the three elastic constants K[sub 1], K[sub 2] and K[sub 3] for the splay, twist and bend deformations, respectively. The results of the simulations are compared with the analytical solutions obtained from continuum theory in order to test the accuracy of the model potential at a quantitative level. This comparison is also made for different temperatures to explore the influence of director fluctuations on the elastic behaviour. [ABSTRACT FROM AUTHOR]

Examines the existing physical activity guidelines for children. Patterns of physical activity for children; Magnitude of difference between male and female physical activities among teenagers; Technologies that have allowed the assessment of youth activity patterns.