Morning compared to afternoon school-based exercise on cognitive function in adolescents

PURPOSE

Adolescents may be less ready to learn in the mornings due to a propensity for waking up later. High-intensity interval exercise (HIIE) has been shown to acutely improve cognitive functioning in teenagers. This within-measures study explored whether the benefit of HIIE differs when delivered in the morning or afternoon.

METHODS

37 teenagers (19 boys, 13.7 ± 0.4 years) each completed 3 trials in school; morning HIIE (MORN), afternoon HIIE (AFTER) and a no-exercise control trial (CON). The HIIE involved 10x10 second sprints, interspersed by 50 s of walking. Cognitive function was assessed using a battery of computerised tasks four times over the course of the day.

RESULTS

Z scores for reaction time, but not proportion of correct responses, were improved 45 min post exercise in the MORN trial (P < 0.01, d = 0.47), and this improvement persisted until the third (P = 0.04, d = 0.34), but not final (P = 0.93, d = 0.01), time point. Global reaction time was not improved 45 min post exercise in the AFTER trial (P = 0.17, d = 0.20). Global reaction time was quicker 45 min post morning exercise compared to the same time point in CON (P = 0.02, d = 0.56) and AFTER (P = 0.01, d = 0.72).

CONCLUSION

HIIE may be more effectual in improving cognitive functioning when delivered in the morning.

The acute influence of amateur boxing on dynamic cerebral autoregulation and cerebrovascular reactivity to carbon dioxide

PURPOSE

The purpose of this study was to investigate the acute effect of head impacts, sustained over the course of three rounds of amateur boxing, on indices of cerebrovascular function.

METHODS

Eighteen university amateur boxers (six female) completed three experimental trials in a randomised order; (1) three rounds of boxing (BOX), (2) an equivalent bout of pad boxing (where no blows to the head were sustained; PAD), and (3) a time-matched seated control trial (CON). Indices of cerebrovascular function were determined immediately before and 45 min after each trial. Specifically, dynamic cerebral autoregulation (dCA) was determined by considering the relationship between changes in cerebral blood velocity and mean arterial pressure during 5 min of squat-stand manoeuvres at 0.05 and 0.10 Hz. Cerebrovascular reactivity was determined using serial breath holding and hyperventilation attempts.

RESULTS

Participants received an average of 40 ± 16 punches to the head during the BOX trial. Diastolic, mean and systolic dCA phase during squat stand manoeuvres at 0.05 Hz was lower after BOX compared to pre BOX (P ≤ 0.02, effect size (d) ≥ 0.74). No other alterations in dCA outcomes were observed at 0.05 or 0.10 Hz. The number of head impacts received during the BOX trial was associated with the change in systolic phase (r = 0.50, P = 0.03). No differences in cerebrovascular reactivity to breath holding or hyperventilation were observed.

CONCLUSIONS

A typical bout of amateur boxing (i.e., three rounds) can subtly alter cerebral pressure-flow dynamics, and the magnitude of this change may be related to head impact exposure.

Exercise intensity and the protection from postprandial vascular dysfunction in adolescents

Acute exercise transiently improves endothelial function and protects the vasculature from the deleterious effects of a high-fat meal (HFM). We sought to identify whether this response is dependent on exercise intensity in adolescents. Twenty adolescents (10 male, 14.3 ± 0.3 yr) completed three 1-day trials: 1) rest (CON); 2) 8 × 1 min cycling at 90% peak power with 75 s recovery [high-intensity interval exercise (HIIE)]; and 3) cycling at 90% of the gas exchange threshold [moderate-intensity exercise (MIE)] 1 h before consuming a HFM (1.50 g/kg fat). Macrovascular and microvascular endothelial function was assessed before and immediately after exercise and 3 h after the HFM by flow-mediated dilation (FMD) and laser Doppler imaging [peak reactive hyperemia (PRH)]. FMD and PRH increased 1 h after HIIE [P < 0.001, effect size (ES) = 1.20 and P = 0.048, ES = 0.56] but were unchanged after MIE. FMD and PRH were attenuated 3 h after the HFM in CON (P < 0.001, ES = 1.78 and P = 0.02, ES = 0.59). FMD remained greater 3 h after the HFM in HIIE compared with MIE (P < 0.001, ES = 1.47) and CON (P < 0.001, ES = 2.54), and in MIE compared with CON (P < 0.001, ES = 1.40). Compared with CON, PRH was greater 3 h after the HFM in HIIE (P = 0.02, ES = 0.71) and MIE (P = 0.02, ES = 0.84), with no differences between HIIE and MIE (P = 0.72, ES = 0.16). Plasma triacylglycerol concentration and total antioxidant status concentration were not different between trials. We conclude that exercise intensity plays an important role in protecting the vasculature from the deleterious effects of a HFM. Performing HIIE may provide superior vascular benefits than MIE in adolescent groups.

Method of Optimizing Motor and Bit Performance for Maximum ROP

Abstract

Downhole motors are widely used to drill vertical, directional and horizontal wells in conjunction with Polycrystalline Diamond Compact (PDC) bits. When a bent housing Positive Displacement Motor (PDM) is oriented for slide drilling to manipulate a well's trajectory, the drill string does not rotate. Consequently, the rate of penetration (ROP) typically decreases. It is therefore important to optimize bottomhole assembly (BHA) performance in conjunction with PDC drill bits. This paper discusses how motor performance data, coupled with an ROP model, can predict the optimal weight-on-bit (WOB) required to derive maximum ROP for a given section of a hole to be drilled. This approach solves the ROP model and determines the ideal WOB with respect to any restrictions that PDM performance equations apply on it. Bit wear is included in the ROP model and an analysis is performed to optimize a given interval of wellbore. The optimization approach is illustrated with two examples for different formation types and one field case comparing the performance of two motors with PDC bits. The optimum WOB, maximum average ROP and differential pressure values are the outputs from the analysis. This analytical approach can be used to determine the optimum PDM/PDC bit combination to achieve maximum ROP through a wide range of operational conditions.

Introduction

Positive Displacement Motors (PDMs) have gained widespread use in vertical, directional and horizontal drilling applications. In directional and horizontal mode, bent housing PDMs are used to manipulate well trajectory (inclination and azimuth) to intersect bottomhole targets. Slide drilling occurs when the bend in the PDM is oriented in a certain direction. During slide drilling, the drill string does not rotate. In slide drilling mode, bit rotation is generated only from the motor as drilling fluid is pumped through the drill string. Drilling in this mode can significantly reduce ROP and increase well costs. Accordingly, overall performance of bit and motor combinations can have an extremely significant impact on drilling costs. In comparison to using a simple approach like mechanical specific energy (MSE) which is a relative 'local' value as a function of instantaneous operating parameters like WOB and RPM only(1), the approach herein can do a global bit run optimization in the pre-planning and follow-up phases, which include bit selection and detailed design parameters, bit wear throughout the bit run as a function of operating parameters and motor selection and performance. MSE does not consider any of these parameters and is not an overall 'global' ROP or $/m optimization tool.

In a PDM, the power section converts hydraulic energy of mud flow into mechanical rotary power ? the reverse action of the Moineau pump principle(2). Each PDM has a helical rotor assembled inside a helical stator. The rotor has one less spiral or lobe than the stator, which results in a continuous seal line between the two. Likewise, the length of helical pitch for the stator is greater than the rotor, which forms cavity spaces between them. These cavities move along the power section from the inlet to outlet by rotating the rotor.

Differential expression of IEG mRNA in rat brain following acute treatment with clozapine or haloperidol: a semi-quantitative RT-PCR study

Antipsychotic drugs have been shown to modulate immediate early gene (IEG) expression in rat brain regions that are associated with schizophrenia, which may be directly linked to their immediate therapeutic benefit. In this study, we analysed the expression profile of a series of IEGs (c-fos, c-jun, fra-1, Krox-20, Krox-24, arc, sgk-1, BDNF and NARP) in six rat brain regions (prefrontal cortex, hippocampus, striatum, nucleus accumbens, thalamus and cerebellum). Rats (n=5) were administered either clozapine (20 mg/kg i.p.), haloperidol (1 mg/kg i.p.) or the appropriate vehicle with pre-treatment times of 1, 6 and 24 h. IEG expression was analysed in these regions by Taqman RT-PCR. The spatial and temporal profile of IEG induction following antipsychotic drug treatment correlates with regions associated with the efficacy and side effect profile of each drug. In particular, sgk-1 expression levels after antipsychotic drug treatment may have predictive value when investigating the profile of a novel antipsychotic drug.

Assessment of the bone status of Nigerian women by ultrasound and biochemical markers

Ultrasound analysis of the calcaneus and serum markers of bone turnover were used to examine the bone status of healthy Nigerian women who reside in an area of the world where dietary calcium intake is generally low and estrogen replacement therapy is not widely available. A total of 218 women (108 premenopausal and 110 postmenopausal) between the ages of 16 and 95 years were enrolled in the study. Broadband ultrasound attenuation (BUA) and speed of sound velocity (SOS) were measured and used to calculate the stiffness index (SI) of the calcaneus. In this cross-sectional study, the Nigerian women exhibited a marked age-dependent decline in SI that was defined by the regression equation SI = 105.9 - 6.62E-3 x Age2. SI was significantly correlated with age (r = -0.41, P < 0.001) and with serum NTx concentrations (r = -0.26, P < 0.001), but not with serum levels of bone-specific alkaline phosphatase (BSAP). Years since menopause was also significantly correlated with SI (r = 0.40, P < 0.001). A significant increase in serum NTx concentration occurred at least a decade before a significant decline in SI was evident. In the total study group, 24% of the women had T-scores indicative of osteopenia and 9% had T-scores indicative of osteoporosis, based on US reference data. Although the reported current incidence of fracture is low in women in sub-Saharan West Africa, these data show that after menopause Nigerian women have a decline in bone quality and increase in bone turnover similar to North American Caucasian women.

Solubilisation of a novel anticonvulsant binding site from pig cortical membranes

The present study describes the solubilisation of the novel anticonvulsant, SB-204269, binding site from pig cortical membranes. Throughout the study the binding of a close analogue of this compound, [125I]-SB-217644 (trans 6- Acetyl-4S-(3-iodobenzoylamino)-3,4-dihydro-2,2-dimethyl-2H-benzo[b ]pyran-3R-ol) was used to monitor the success of the solubilisation procedure. [125I]-SB-217644 was an ideal mechanistic tool for quantifying the binding to this novel anticonvulsant site, with a high specific activity and affinity (K(D) of 3 nmol/l). Optimum conditions for the solubilisation of this anticonvulsant binding site were investigated using a multifactorial experimental design to assess a large number of variables. Detergent type, detergent-protein ratio, absence of Mg2+ and temperature were deemed to be important factors. However, the increases observed in binding site specific activity were minimal compared with those achieved for yields. Maximum percentage yields of binding activity (25%) were achieved with a low concentration of the zwitterionic detergent, CHAPS, in the presence of a low protein concentration. This yield was further enhanced on combining mixtures of detergents. The highest recovery (37%) was achieved with a 50:50 (v:v; 1.5 x critical micelle concentration) mixture of the ionic detergent, sodium cholate, and the non-ionic detergent, MEGA-10. In summary, we report the successful solubilisation of a novel anticonvulsant binding site, identified by its selective affinity for SB-204269 and its analogues. The recovery of nearly 40% of the target binding sites from the starting material should provide a good starting point for the purification of this protein.

Neuron-specific localisation of the TR3 death receptor in Alzheimer's disease

Death receptors are associated with the homeostatic and pathologic induction of cell death. TR3 is a recently characterised member of the death receptor family that is expressed in the adult brain. In order to establish the role of TR3 in acute CNS disease and chronic neurodegeneration, we analysed brain regions from Alzheimer's disease (AD), stroke and neurotrauma patients, using a novel anti-peptide antibody generated to an exposed epitope in the extracellular domain of the receptor. We show a statistically significant increase in TR3 protein levels in AD brain samples but not in stroke, neurotrauma or control samples. The increase observed for TR3 was specific to neurons in regions associated with AD pathology. This is the first report describing the neuron-specific regulation of a death receptor in chronic disease and may indicate that a TR3 receptor-mediated signalling pathway is involved in AD-associated neuronal loss.

Peroxisome proliferator-activated receptor-gamma agonist, rosiglitazone, protects against nephropathy and pancreatic islet abnormalities in Zucker fatty rats

Rosiglitazone (BRL 49653), a peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist and potent insulin action-enhancing agent, was given in the diet (50 micromol/kg of diet) to male Zucker rats ages 6-7 weeks for 9 months (prevention group). In this treatment mode, rosiglitazone prolonged the time to onset of proteinuria from 3 to 6 months and markedly reduced the rate of its subsequent progression. Progression was also retarded when treatment was commenced (intervention group) after proteinuria had become established (4 months; ages 24-25 weeks). In either treatment mode, rosiglitazone normalized urinary N-acetyl-beta-D-glucosaminidase activity, a marker for renal proximal tubular damage, and ameliorated the rise in systolic blood pressure that occurred coincidentally with the development of proteinuria in Zucker fatty control rats. The renal protective action of rosiglitazone was verified morphologically. Thus in the prevention group there was an absence of the various indexes of chronic nephropathy that were prominent in the Zucker fatty control group, namely, glomerulosclerosis, dilated tubules containing proteinaceous casts, a loss of functional microvilli on the tubular epithelium, and varying degrees of chronic interstitial nephritis. An intermediate pathology was observed in the intervention group. Also, pancreatic islet hyperplasia, ultrastructural evidence of beta-cell work hypertrophy, and derangement of alpha-cell distribution within the islet were prominent features of Zucker fatty control rats, but these adaptive changes were ameliorated (intervention group) or prevented (prevention group) by rosiglitazone treatment. These data demonstrate that treatment of Zucker fatty rats with rosiglitazone produced substantial protection over a prolonged period against the development and progression of renal injury and the adaptive changes to pancreatic islet morphology caused by sustained hyperinsulinemia.

Estimation of the partitioning characteristics of drugs: a comparison of a large and diverse drug series utilizing chromatographic and electrophoretic methodology

1-Octanol-water log P values for a large number of standards and bioactive molecules have been correlated to the logarithm of the corresponding capacity factors determined by reversed-phase high-performance liquid chromatography, using a novel dynamically coated phase, containing phosphatidylcholine. Similarly a correlation was also obtained for log P and capacity factors determined by micellar electrokinetic capillary chromatography (MECC), involving the use of phosphatidylcholine--bile acid mixed micelles in the separation buffer. Statistical analysis of data obtained via both methods has shown that either method will give reliable log P predictions, although MECC is generally more useful for neutral and basic compounds. It is recommended that, as both methods can easily be set up in an analytical laboratory, their combined use provides rapid methodology for the confident estimation of hydrophobicity, as measured by log P for the widest diversity of chemical structures.

Sensitization of human atrial 5-HT4 receptors by chronic beta-blocker treatment

BACKGROUND

Chronic treatment of patients with beta-blockers induces beta 2-adrenergic receptor hyperresponsiveness in atrium and sinoatrial node. To investigate whether other atrial Gs protein-coupled receptors also become hyperresponsive after chronic treatment with beta-blockers, we investigated 5-HT4 receptors in tissues and myocytes, which mediate serotonin-evoked increases of both contractile force and cAMP levels.

METHODS AND RESULTS

Isolated right atrial strips from patients who had been chronically treated or not treated with a beta-blocker were set up to contract. In tissues from beta-blocker-treated patients (n = 27), the maximum inotropic response to serotonin was 56 +/- 3% (mean +/- SEM) of the effect elicited by (-)-isoproterenol (200 mumol/L) compared with a response of 19 +/- 6% in tissues from non-beta-blocker-treated patients (n = 13) (P < .001). The responsiveness of the tissues to Ca2+ was unchanged by chronic beta-blocker treatment. Serotonin (1 and 10 mumol/L) increased tissue cAMP levels, the increase with 10 mumol/L being significantly greater (P < .05) in tissues from beta-blocker-treated (n = 9) than in non-beta-blocker-treated (n = 7) patients. In paced atrial myocytes, serotonin caused concentration-dependent increases in contraction. Myocytes obtained from atria of beta-blocker-treated patients were more sensitive (P < .01) to the effects of serotonin (-log EC50, 7.9 +/- 0.2 mol/L; n = 12) than myocytes obtained from non-beta-blocker-treated patients (-log EC50, 7.3 +/- 0.2 mol/L, n = 12). Chronic beta-blocker treatment had no effect on forskolin-evoked myocyte responses. Carbachol (1 mumol/L) suppressed the effects of both serotonin (n = 6) and (-)-isoproterenol (n = 6) in the same atrial myocyte.

CONCLUSIONS

Chronic treatment of patients with beta-blockers causes atrial 5-HT4 receptor inotropic hyperresponsiveness and enhanced serotonin-evoked increases in cAMP levels. This may be due to modified cross talk between 5-HT4 receptors, beta-adrenergic receptors, and muscarinic receptors.

Effects of electrocardiograph frequency filters on P-QRS-T amplitudes of the feline electrocardiogram

OBJECTIVE--To determine whether standard manual frequency filters in the ON and OFF settings affected P-QRS-T voltages, discover whether recorded P-QRS-T voltages vary between commercial electrocardiographs, assess effects of frequency filters on base-line artifact, and evaluate ECG frequency content by high-fidelity recordings subjected to digital filters with variable frequencies. DESIGN--Sequential 10-lead ECG were recorded in 30 cats, using 3 commercial electrocardiographs to assess effects of manual frequency filters on the P-QRS-T wave forms. Three clinically normal cats were evaluated for ECG frequency content. ANIMALS--Thirty cats (13 with hypertrophic cardiomyopathy; 4 with restrictive cardiomyopathy; 3 hyperthyroid; 1 with ventricular septal defect; 1 with aortic stenosis; and 8 with no detectable cardiovascular disease). Three additional clinically normal cats were studied for effects of frequency filters on the ECG frequency content. PROCEDURES--Ten-lead ECG were recorded on each cat by use of 3 commercial electrocardiographs sequentially. For each machine, a recording was made with manual filters ON, immediately followed by a recording with manual filters OFF. High-fidelity lead-II ECG recordings were made with filters set with their rolloff frequency at 0.1 Hz and 3.0 kHz; output voltage (0.2 mV/V) was fed to an analog-to-digital converter, then to attendant software, which sampled the signal at 6 kHz with a 12-bit sampler, and were digitally filtered at various corner frequencies. RESULTS--Voltages recorded by all 3 electrocardiographs were greatest when filters were OFF (most prominent on R- and S-wave voltages). In all recorded leads, R-wave voltage was significantly greater when filters were OFF than ON. Comparison of voltages indicated significant (P < 0.05) differences between R-wave voltages recorded in all leads with manual filters ON, but not with filters OFF. With filters ON, each electrocardiograph produced a smaller percentage of recordings with moderate to severe baseline artifact than with filters OFF. R-Wave amplitudes of high-fidelity lead-II ECG were significantly decreased with digital filters set at corner frequencies < 150 Hz. CONCLUSIONS--Significant (P < 0.05) voltage attenuation was recorded by each of the 3 commercial electrocardiographs when frequency filters were ON, compared with OFF. Comparison of waveform voltages among electrocardiographs with filters ON indicated significant variation in R-wave amplitudes in all leads. With manual filters ON, each electrocardiograph recorded a smaller percentage of recordings with baseline artifact than with filters OFF. Substantial frequency components > or = 150 Hz are present in the feline ECG waveform. Thus, filters with frequencies < 150 Hz markedly attenuate the feline R wave. CLINICAL RELEVANCE--Attenuation of feline ECG signals occurs with use of commercial electrocardiographs and varies greatly between manufacturers. This is attributable largely to internal manual frequency filters. These consequences may be important when applying standard feline reference values or when equivocal voltage measurements are recorded.

Cholesterol lowering and bile acid excretion in the hamster with cholestyramine treatment

Cholestyramine was administered to hamsters at 6 doses in the diet for 1 week. Plasma cholesterol, LDL + VLDL cholesterol and HDL cholesterol were measured after this period. Bile acid excretion was measured in faeces collected over the final 24 h of the experiment. A dose-response curve for each parameter measured was constructed using data from individual hamsters. For the bile acid and the cholesterol measurements a maximum response was observed at the highest doses. A correlation between the bile acids excreted over 24 h and the LDL + VLDL cholesterol showed that the maximum effect of cholestyramine on lowering plasma and lipoprotein cholesterol occurred at a submaximal excretion level of bile acids. Comparison of the efficiency of cholestyramine in reducing plasma cholesterol in the hamster with limited data in the dog and in man suggest that a greater lowering of plasma cholesterol is achieved in the dog and in man for an equivalent increase in bile acid excretion caused by the sequestrant. As is already known, cholestyramine treatment caused an increase in hepatic cholesterol 7 alpha-hydroxylase and HMG-CoA reductase activity. Interestingly in this study the novel observation was made that the bile acid sequestrant reduced the activity of hepatic acyl-CoA: cholesterol acyltransferase.

Granulomatous slack skin: clonal rearrangement of the T-cell receptor beta gene is evidence for the lymphoproliferative nature of a cutaneous elastolytic disorder

Granulomatous slack skin (GSS) is characterized by the slow evolution of bulky, erythematous skin folds that have a granulomatous histology, and show destruction of dermal elastic tissue. Several cases have been putatively associated with Hodgkin's disease, and histologic similarities to mycosis fungoides have also been noted. We examined tissue from 3 cases of GSS to determine whether the condition was inflammatory or lymphoproliferative in nature. We found an abnormal, monomorphous T-helper cell immunophenotype, and in all 3 cases, clonal rearrangement of the T-cell receptor beta gene. We conclude that GSS is an indolent cutaneous T-cell lymphoma associated with granulomatous inflammation that mediates elastolysis, producing a distinctive clinical appearance.

The immunoglobulin octanucleotide: independent activity and selective interaction with enhancers

The thymidine kinase (tk) promoter of herpes simplex virus includes an octanucleotide sequence motif (ATTTGCAT) that is also an essential component of immunoglobulin kappa gene promoters. In the absence of an enhancer, tk promoter derivatives that contain this element support a higher rate of transcription than those that lack it. The action of the kappa enhancer augments that of the octanucleotide in B lymphoid cells; when both elements are present, tk promoter activity is increased by more than an order of magnitude. In contrast, the presence of the octanucleotide in this promoter markedly reduces its response to a nonimmunoglobulin enhancer. These results suggest that the octanucleotide may mediate a selective interaction among promoters and enhancers.

Ferritin content in human cancerous and noncancerous colonic tissue

Tumor tissue samples from 25 patients with adenocarcinoma of the colon, twelve related samples of normal colons as well as five serum specimens from the same patients were analyzed for ferritin. The average ferritin content of the tumor tissue was 788 ng/mcp with a range of 47-1,745 ng/mcp. The average ferritin content of normal colon mucosa was 115 ng/mcp with a range of 32-230 ng/mcp. Two specimens of metastatic colon cancer taken from the retroperitoneal space and liver, respectively, contained 3,867 and 2,827 ng/mcp of ferritin. The ferritin content of the tumor tissue was higher than that of the normal colon in 8 of 9 patients who had specimens obtained from both sites. The amount of ferritin found in tumor tissue was independent of sex, age, and the site of the original tumor. This study shows that the ferritin content of colon neoplasms is elevated and indicates that the tumor tissue may be the direct source of elevated serum levels of ferritin previously observed in cancer patients.

Stage IB adenocarcinoma of the cervix: metastatic potential and patterns of dissemination

The metastatic potential patterns of dissemination have been investigated in 150 patients with Stage 1B adenocarcinoma of the cervix treated during a 20-year period from 1956 to 1977. All cases with the exception of one were treated with a combination of intracavitary radium implants followed by a radical surgical procedure with pelvic lymph node dissection. It was found that the incidence of pelvic metastases and distant recurrences and the survival rates were the same as in previously published reports for squamous cell carcinomas treated in the same manner. In one respect adenocarcinomas showed a significant difference when compared with squamous cell cancers: The incidence of residual tumor in the hysterectomy specimens after intracavitary treatment was much higher (30% versus 11%). This is considered a strong argument for surgical treatment of patients with early stages of adenocarcinoma of the cervix.

Hereford Hospital Prescribing Study: Description and Usefulness1

The mode of operation of a computer-based information system designed to link information about drug usage to diagnostic data is described. Details of the cost of this system are given. It is shown that the running costs are approximately £20 000 per year. Examples are given of the uses made of the data collected.

The effects of a single dose of 7,12-dimethylbenz(a)-anthracene on the epidermis and hair follicles of mice, with notes on concurrent changes in the ovaries and adrenals

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