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.

Coupling of RYR1 and L-type calcium channels via calmodulin binding domains

In skeletal muscle the L-type Ca2+ channel directly controls the opening of the sarcoplasmic reticulum Ca2+ release channel (RYR1), and RYR1, in turn, prevents L-type Ca2+ channel inactivation. We demonstrate that the two proteins interact using calmodulin binding regions of both proteins. A recombinant protein representing amino acids 1393-1527 (D1393-1527) of the carboxyl-terminal tail of the skeletal muscle L-type voltage-dependent calcium channel binds Ca2+, Ca2+ calmodulin, and apocalmodulin. In the absence of calmodulin, D1393-1527 binds to both RYR1 and a peptide representing the calmodulin binding site of RYR1 (amino acids 3609-3643). In addition, biotinylated R3609-3643 peptide can be used with streptavidin beads to pull down [3H]PN200-110-labeled L-type channels from detergent-solubilized transverse tubule membranes. The binding of the L-type channel carboxyl-terminal tail to the calmodulin binding site on RYR1 may stabilize the contact between the two proteins, provide a mechanism for Ca2+ and/or calmodulin regulation of their interaction, or participate directly in functional signaling between these two proteins. A unique aspect of this study is the finding that calmodulin binding sequences can serve as specific binding motifs for proteins other than calmodulin.

Determinants for calmodulin binding on voltage-dependent Ca2+ channels

Calmodulin, bound to the alpha(1) subunit of the cardiac L-type calcium channel, is required for calcium-dependent inactivation of this channel. Several laboratories have suggested that the site of interaction of calmodulin with the channel is an IQ-like motif in the carboxyl-terminal region of the alpha(1) subunit. Mutations in this IQ motif are linked to L-type Ca(2+) current (I(Ca)) facilitation and inactivation. IQ peptides from L, P/Q, N, and R channels all bind Ca(2+)calmodulin but not Ca(2+)-free calmodulin. Another peptide representing a carboxyl-terminal sequence found only in L-type channels (designated the CB domain) binds Ca(2+)calmodulin and enhances Ca(2+)-dependent I(Ca) facilitation in cardiac myocytes, suggesting the CB domain is functionally important. Calmodulin blocks the binding of an antibody specific for the CB sequence to the skeletal muscle L-type Ca(2+) channel, suggesting that this is a calmodulin binding site on the intact protein. The binding of the IQ and CB peptides to calmodulin appears to be competitive, signifying that the two sequences represent either independent or alternative binding sites for calmodulin rather than both sequences contributing to a single binding site.

Extraperitoneal laparoscopic aortic control with endovascular visualization of a stent-graft combination

OBJECTIVES

to demonstrate the feasibility of minimally invasive approaches to the aorta using retroperitoneal laparoscopy and to clamp the aorta to give views for perfemoral aortic angioscopy.

METHODS

using retroperitoneal laparoscopy facilitated by balloon dissection the authors developed a new approach to the infrarenal abdominal aorta, in six pigs, to allow control of aortic blood flow. Aortic stent-grafts were then deployed via femoral arteriotomy, and after flushing the blood from the aorta, the stent-grafts were visualized by angioscopy.

RESULTS

accurate positioning and patency of the stent-grafts was ascertained by direct vision angioscopy in all cases.

CONCLUSIONS

this series shows that extraperitoneal laparoscopic aortic dissection is feasible and direct endovascular visualization of the aortic lumen can be performed. This may find a role as an adjunct to endovascular techniques such as endovascular stent-graft placement, by aortic angioscopy following minimally-invasive aortic clamping.

Determining consistency of elbow joint threshold angle in elbow flexor muscles with spastic hypertonia

BACKGROUND AND PURPOSE

Threshold angle, the point in passive range of motion where a muscle response or torque change is elicited, may be a potentially valid measure of hypertonus. Because the relationship of initial muscle length to threshold angle has not been addressed previously, this preliminary study examined whether starting elbow joint position and speed of stretch to elbow flexor muscles affect threshold angle.

SUBJECTS

Five subjects with stroke-induced hypertonia of the elbow flexor muscles participated.

METHODS

Two starting angles and two designated stretch speeds were applied randomly by a torque motor at each of three testing sessions.

RESULTS

Starting angle, subject, and session affected threshold angle. A 90-degree starting angle at a stretch speed of approximately 1.0 radian/s produced the most consistent threshold angles between sessions within subjects, and threshold angle was relatively consistent for some subjects, irrespective of speed.

CONCLUSION AND DISCUSSION

If future research indicates that these data can be generalized, the use of threshold angle as a consistent measure of hypertonia will require comparison within individuals, use of a consistent starting angle, and a movement condition of a 90-degree starting angle and an approximate movement speed of 1.0 radian/s across sessions.

Preoperative assessment of the high-risk patient for lung resection

BACKGROUND

We wanted to determine if cardiopulmonary exercise testing could better identify the threshold where physiologic function is irreparably impaired for patients with borderline pulmonary function who are being considered for lung cancer resection.

METHODS

We performed an open, prospective preoperative trial and a postoperative outcome evaluation with a combined medical, surgical, and exercise physiology evaluation at three university hospitals. All eligible patients had spirometry, lung volume determination, and quantitative perfusion scanning and performed a cardiopulmonary stress test, stair climbing, and a 12-minute walk for distance. Functional status was determined with an Eastern Cooperative Oncology Group score, a dyspnea score, and a cardiopulmonary risk index.

RESULTS

We identified 12 patients who met strict criteria for borderline pulmonary function during a 1-year study period. The mean forced expiratory volume in 1 second (FEV1) was 1.38 L (48% of predicted). The mean predicted postoperative FEV1 based on pneumonectomy was 700 mL. Eleven of the patients did the stair climb and 10 passed. All 12 patients achieved a maximum oxygen consumption greater than or equal to 10 mL x kg(-1) x min(-1) (mean value, 13.8 mL x kg(-1) x min(-1)). Thirteen operations were performed on the 12 patients. Nine complications occurred in 7 patients.

CONCLUSIONS

Patients with borderline pulmonary function can undergo resection safely if they have an FEV1 equal to or greater than 1.6 L or 40% of its predicted value, a predicted postoperative FEV1 of 700 mL or more, a maximum oxygen consumption of 10 mL x kg(-1) x min(-1) or greater, or stair climbing of three flights or more. Cardiopulmonary stress testing and stair climbing add valuable clinical information for patients with an FEV1 of less than 1.6 L.

Spinal dysplasia with stump tail and hind limb paralysis in a laboratory bred cat

A case is presented of a specified pathogen free bred cat which was apparently tail-less at birth and at three weeks of age revealed hind limb paralysis. The animal was euthanized at 4 weeks and X-radiography revealed an abnormal spinal curvature, greatly reduced caudal vertebrae and abnormal pelvic development. A small tail was dissected at post-mortem, but other abnormalities were not seen.

Haemodynamic and neurohumoral response in heart failure produced by rapid ventricular pacing

OBJECTIVE

The aim was to determine the exact sequence of hormone changes during the progression of fluid retention in a canine model of "congestive cardiac failure" induced by rapid right ventricular pacing, and during recovery when pacing is stopped.

METHODS

Rapid ventricular pacing at a rate of 250 pulses.min-1 was used in six mongrel dogs with implanted right ventricular pacemakers. Right heart haemodynamics were measured by means of Swan Ganz catheterisation, allowing flow measurement by thermodilution and pressure measurement by external manometry. Plasma renin activity, arginine vasopressin, and atrial natriuretic factor were assayed on venous blood samples by radioimmunoassay. Noradrenaline was assayed by high pressure liquid chromatography.

RESULTS

The onset of rapid pacing was accompanied by a fall in cardiac output and a rise in pulmonary arterial, pulmonary capillary wedge, and right atrial pressures. Noradrenaline and atrial natriuretic factor rose. Plasma renin activity showed an initial fall followed by a rise, and arginine vasopressin was unchanged in the first 8 h. When rapid pacing was continued for a further 35 d, clinical signs of fluid retention appeared by day 28, by which time cardiac output had fallen, and central pressures risen further. Atrial natriuretic factor peaked at around 14 d whereas plasma renin activity, arginine vasopressin, and noradrenaline tended to reach a plateau at about d 20 and then to show further increases as clinical signs of fluid retention appeared; this was most marked with plasma renin activity. Cessation of pacing at d 35 caused a rapid reversal (increase) of cardiac output but a more gradual reversal (decrease) of right heart pressures over 5 d; only wedge pressure returned to base line. Arginine vasopressin and plasma renin activity fell rapidly to around 40% of the final pacing levels and reached basal values after 8 h and 48 h respectively. Noradrenaline fell after 8 h and reached basal levels in 5 d. Atrial natriuretic factor fell quickly by 60% after 8 h but remained above basal levels for 5 d. At the end of pacing, body weight fell rapidly in conjunction with a large diuresis.

CONCLUSIONS

These findings are compatible with a major role of one or more of renin, vasopressin, and noradrenaline in the pathophysiology of the fluid retention of heart failure; the manifestations are not counteracted by the rise in atrial natriuretic factor.

The influence of prostaglandin E1 on systemic and pulmonary haemodynamics after aortic surgery

The influence of a peroperative prostaglandin E1 (PGE1) infusion on systemic and pulmonary haemodynamics in a porcine model of aortic surgery was studied. Twenty-four pigs were randomised to PGE1 (100 ng/kg/min) or 0.9% Saline as placebo. Haemaccel was then infused to maintain a central venous pressure (CVP) of greater than 4 less than 6 mmHg and pulmonary artery wedge pressure (PAWP) of greater than 3 less than 5 mmHg. Standardised aortic surgery consisted of midline laparotomy, small bowel exteriorisation, 1.5 h aortic clamping and 1 h shock before resuscitation. Serial measurements of blood pressure (BP), cardiac output (CO), pulmonary vascular resistance (PVR), pulmonary shunt (A-V shunt), and arterial PO2 (PaO2) were recorded during and three days after surgery. Volume loading with Haemaccel prevented a significant fall in initial BP on PGE1 at 95.1 +/- 48 mmHg compared to 102 +/- 4.9 mmHg in control animals with similar CO in the two groups. Following release of the aortic clamp all animals became profoundly hypotensive with BP falling to 74.6 +/- 3.0 and 68.7 +/- 3.2 mmHg for PGE1 and placebo respectively, but CO was protected in those animals receiving PGE1 at 1.92 +/- 0.04 compared to 1.67 +/- 0.1 L/min/m2 on placebo and remained significantly higher following resuscitation and three days later (P less than 0.05). PGE1 also reduced the marked rise in pulmonary vascular resistance to 922 +/- 84 dynes-s/cm5/m2 during shock in control animals to only 555 +/- 30 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Cost busters fair: increasing staff awareness of cost effective practice

Losses in excess of $1,000,000 from uncharged supplies, which were inadequately documented in the medical record, prompted the formation of a multidepartmental task force to attack the problem. A project, the Co$t Busters Fair, was planned and developed to target nurses, physicians, nursing assistants, and medical attendants. Goals of the fair were to increase awareness of factors affecting cost and to clarify misconceptions about charting practices.

Emetic food poisoning caused by Bacillus cereus

Symptoms of acute food poisoning developed in eight members of a group who ate lunch at a cafeteria. After brief incubation periods, all affected individuals complained of nausea and abdominal cramps. Four persons promptly experienced vomiting. None of those affected was found to have fever and all recovered with 48 hours. Epidemiologic investigation incriminated macaroni and cheese as a cause of the illness and samples of this food contained large numbers of Bacillus cereus. Previous outbreaks of B cereus emetic food poisoning have been associated with consumption of contaminated fried rice and may occur after ingestion of other foods.