Physical Activity Is Associated with Attention Capacity in Adolescents

OBJECTIVE

To assess the relationships among physical activity, measured objectively, and attention capacity in European adolescents.

STUDY DESIGN

The study included 273 adolescents, aged 12.5-17.5 years, who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence Study. Participants wore a uniaxial accelerometer for 7 days to measure physical activity. The d2 Test of Attention was administered to assess attention capacity. Multivariate analyses were used to study the association of attention capacity with each measure of physical activity. Receiver operating characteristic analysis was performed to determine thresholds that best discriminate between low and good attention capacity.

RESULTS

After controlling for potential confounding variables (age, sex, body mass index, parental educational level, fat mass, aerobic fitness, and center), adolescents' attention capacity test performances were significantly and positively associated with longer time spent in moderate or moderate-to-vigorous physical activity (MVPA) in free-living conditions (P < .05). Receiver operating characteristic curve analyses revealed that the physical activity thresholds that best discriminated between low/good attention capacities were ≥41 min·day(-1) for moderate, ≥12 min·day(-1) for vigorous, and ≥58 min·day(-1) for MVPA.

CONCLUSION

These findings suggest that promoting MVPA may be have a beneficial effect on attention capacity, an important component of cognition, in adolescents.

Evidence of involvement of the PLAG1 gene in lipoblastomas

Previous cytogenetic studies have demonstrated that the majority of lipoblastomas show rearrangements, in particular translocations and insertions, with breakpoints in 8q11-13. Here we present evidence for involvement of the developmentally regulated zink finger gene PLAG1 in these rearrangements. Northern blot and RT-PCR analyses revealed overexpression of PLAG1 in two lipoblastomas. Using immunohistochemistry, expression of the PLAG1 protein was also demonstrated in tissue sections from two lipoblastomas, one of which had a t(3;8)(q13.1;q12) translocation and the other a t(1;6)(q42;p22) translocation. Since no aberrant PLAG1 transcripts could be detected, it is likely that the gene may be activated by promoter swapping/substitution or alternatively by an as yet unknown mechanism. Our findings indicate that PLAG1 activation is a recurrent event in lipoblastomas and that PLAG1 is likely to be the target gene on chromosome 8 in these tumors.

Dexamethasone responsiveness of a major glucocorticoid-inducible CYP3A gene is mediated by elements unrelated to a glucocorticoid receptor binding motif

Elements responsible for dexamethasone responsiveness of CYP3A23, a major glucocorticoid-inducible member of the CYP3A gene family, have been identified. DNase I footprint analysis of the proximal promoter region revealed three protected sites (sites A, B, and C) within the sequence defined by -167 to -60. Mutational analysis demonstrated that both sites B and C were necessary for maximum glucocorticoid responsiveness and functioned in a cooperative manner. Interestingly, neither site contained a glucocorticoid responsive element. Embedded in site C was an imperfect direct repeat (5'-AACTCAAAGGAGGTCA-3'), showing homology to an AGGTCA steroid receptor motif, typically recognized by the estrogen receptor family, while site B contained an ATGAACT direct repeat; these core sequences were designated dexamethasone response elements 1 and 2 (DexRE-1 and -2), respectively. Neither element has previously been associated with a glucocorticoid-activated transcriptional response. Conversion of the DexRE-1 to either a perfect thyroid hormone or vitamin D3 responsive element further enhanced induction by dexamethasone. Gel-shift analysis demonstrated that glucocorticoid receptor did not associate with either DexRE-1 or -2; hence, glucocorticoid receptor does not directly mediate glucocorticoid induction of CYP3A23. These unusual features suggest an alternate pathway through which glucocorticoids exert their effects.

Global feature extraction operations for near-sensor image processing

Near-sensor image processing (NSIP) is a new approach to low-level image processing in which the ability to perform global operations is crucial. We define a 2-D global logic unit (GLU), which consists of simple logical circuits arranged in a regular net, and describe how to perform powerful segmentation and feature-extracting operations using this net. Typical segmentation operations performed by the net are hole filling, smallest circumscribing rectangle, thresholding with hysteresis, and arbitrary propagation patterns. We describe how to obtain features like the position of an object in the image. Finally, we show that the NSIP concept, including the global functions, can be implemented in a single chip using today's VLSI technology.

Near-sensor image processing: a new paradigm

The paper introduces the concept of near-sensor image processing. By this, the authors mean techniques in which the physical properties of the image sensor itself is utilized to do part of the signal processing task. It is shown that the analog-temporal behavior of photodiodes combined with thresholding amplifiers can be used favorably to do certain low-level image processing tasks including median filtering and convolution. The given examples also show how adaptivity to different light levels can be achieved in a natural way. To extract features from the image, such as moments and shape factors, the authors introduce a simple measurement function.

Short-term retinoic acid treatment increases in vivo, but decreases in vitro, epidermal transglutaminase-K enzyme activity and immunoreactivity

Epidermal transglutaminase-K is believed to catalyze the covalent linking of loricrin and involucrin to form cross-linked (CE) envelopes. In normal skin, transglutaminase-K is expressed as a band immediately below the stratum corneum, whereas in psoriasis and healing skin its expression is considerably expanded throughout the suprabasal layers. We have investigated whether the hyperproliferative state induced by short-term application of topical retinoic acid is similarly characterized by an increase in transglutaminase-K enzyme activity and immunoreactivity. Retinoic acid (0.1% cream) or vehicle were applied to human skin and occluded for 4 d. Skin biopsies were obtained for measurement of transglutaminase-K and transglutaminase-C activity and immunoreactivity. For comparison, cultured normal human keratinocytes were incubated for 4 d in the presence of 1 microM retinoic acid and the subsequent transglutaminase-K activity and immunoreactivity measured. Transglutaminase-K activity was increased 2.8 times in retinoic acid compared to vehicle-treated skin (p less than 0.005, n = 12) whereas there was no significant difference in transglutaminase-C activity. However, transglutaminase-K mRNA levels were not significantly different between retinoic acid- and vehicle-treated skin. In vehicle-treated skin, transglutaminase-K immunoreactivity was limited to a narrow, substratum corneal band, but was considerably expanded in a diffuse suprabasal pattern in retinoic acid-treated epidermis. In contrast, transglutaminase-K immunostaining was decreased and its enzymatic activity reduced sixfold in retinoic acid-treated keratinocytes (p less than 0.01, n = 4). These results demonstrate that retinoic acid treatment in vivo, in contrast to in vitro, leads to not only increased transglutaminase-K protein expression but also increased enzymatic activity in the absence of detectable increases in mRNA levels. These data, taken with the previously reported lack of in vivo modulation of the differentiation markers keratins 1 and 10 by retinoic acid, indicate that certain aspects of keratinocyte terminal differentiation that are altered in vitro by retinoic acid do not occur in vivo in human skin.

Induction of proliferation of growth-inhibited keratinocytes and fibroblasts in monolayer culture by sodium lauryl sulfate: comparison with all-trans retinoic acid

We have previously shown that all-trans retinoic acid (RA) has the capacity to stimulate proliferation of growth-inhibited human epidermal keratinocytes and growth-inhibited human dermal fibroblasts. The same treatment also stimulates extracellular matrix synthesis by fibroblasts (J Invest Dermatol 93:449; 94:717). In the present study we have examined the capacity of sodium lauryl sulfate to stimulate keratinocyte and fibroblast proliferation under the same conditions. Our data show that both cell types are stimulated to proliferate. Sodium lauryl sulfate is less potent than RA; it requires a higher molar concentration to achieve optimal stimulation and the number of responding cells at optimal concentrations is less with sodium lauryl sulfate than with RA. Further, there is a rapid onset of toxicity at concentrations of sodium lauryl sulfate that are only slightly higher than the optimal stimulatory concentration. Finally, sodium lauryl sulfate is less effective than RA in stimulating production of extracellular matrix (fibronectin, thrombospondin, and laminin) by dermal fibroblasts. Despite its ability to partially mimic RA as a stimulant of keratinocyte and fibroblast growth, sodium lauryl sulfate does not activate chloramphenicol acetyl transferase in cells co-transfected with retinoic acid receptors and a retinoic acid responsive element linked to the chloramphenicol acetyl transferase gene.

Cyclosporine A metabolism by cytochrome P-450III occurs in microsomes from rat liver but not from normal epidermis or psoriatic lesions

Cyclosporine A is efficacious in the treatment of psoriasis when taken orally or injected intralesionally but not topically. Lack of penetration to necessary locations or rapid metabolism during passage through the epidermis may account for the ineffectiveness. Cytochromes P-450III in the liver are known to be involved in cyclosporine metabolism and inactivation. This study was undertaken to determine if an epidermal cytochrome P-450III exists that can inactivate topical cyclosporine A. Rats were treated with the macrolide antibiotic erythromycin to induce the cytochrome P-450III family of enzymes. Microsomal fractions were prepared from liver and epidermis of rats and from lesional areas of psoriasis patients. NADPH cytochrome C reductase activity was determined as a positive control for microsomal enzymatic activity. Formation of metabolite 1, the predominant metabolite of cyclosporine A, by liver microsomes was increased 193% after 10 d erythromycin treatment. The cytochrome P-450 dependent activity in microsomes from the epidermis of control and erythromycin-treated rats and in microsomes from psoriatic tissue was at the detection limits of the assay system. Cytochrome P-450III gene family mRNA were detectable by polymerase chain reaction in liver but not in psoriatic or normal epidermis. The lack of detectable P-450III mRNA and the absence or minimal conversion of cyclosporine A to inactive metabolites by epidermal microsomes suggest that the ineffectiveness of topical cyclosporine A in psoriasis may not be due to inactivation of cyclosporine A by cytochrome P-450 in the skin.

Characterization of the microsomal cytochrome P-450 species induced in rat liver by trans-stilbene oxide

trans-Stilbene oxide differs from the classical inducers of drug-metabolizing enzymes, phenobarbital and 3-methylcholanthrene, in that it induces the so-called phase II activities, epoxide hydrolase and glutathione S-transferase, to a much larger extent than it induces cytochrome P-450. Nonetheless, the level of cytochrome P-450 in liver microsomes from rats treated with trans-stilbene oxide is increased significantly to twice the control value. The existence of a number of different isozymes of cytochrome P-450 has now been clearly demonstrated and in the present study we have posed the question. What form(s) of cytochrome P-450 is induced by trans-stilbene oxide? A number of criteria including substrate specificity, pattern of benzo(a)pyrene metabolism, sensitivity to inhibitors, substrate binding spectra, ethylisocyanide binding spectra, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and crossed immunoelectrophoresis were used to answer this question. It seems clear that trans-stilbene oxide induces the same form(s) of cytochrome P-450 as phenobarbital.

Critical closing pressure and vasomotor tone in the hind leg and the kidney of the cat

The isolated vascular beds of the hind leg and kidney in cats have been studied by analysis of the pressure-time curves obtained in the distal segment of the artery following occlusion of the arterial blood supply. Arterial flow after 2–3 minutes of occlusion becomes ‘zero,’ according to the criterion used (less than 0.0067 ml/min.), at an arteriovenous pressure difference of 7.8 ± 4.5 (S.D.) mm Hg in the leg and 7.0 ± 3.6 mm Hg in the kidney. Increased resistance to flow has been produced in both the leg and kidney by electrical stimulation of vasomotor nerves, intra-arterial injection of noradrenaline, lowering of the temperature of the local arterial blood and by increasing tissue pressure. The pressure-time curves show a slow but continuous drop and zero arterial flow, i.e. a ‘critical closure,’ is not obtained within the occlusion period. Decreased resistance to flow has been produced in the leg by denervation and by infusion of a ganglionic-blocking agent. Then, the pressure-time curves, as under normal conditions, show a final horizontal level of pressure (zero arterial flow) and the pressure at this point is lower than in the control tests. It is concluded that the level of arterial pressure at zero arterial flow (if obtained) is determined largely by the vasomotor tone and the tissue pressure, when the venous pressure is below 10 mm Hg. Considerable changes in resistance to flow occur with very small changes in the ‘minimum arteriovenous pressure difference’ required for flow. That ‘zero’ arterial flow is obtained only under special conditions would seem to limit the practicability of using critical closing pressure as a measure of vasomotor tone.