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PubMed1996

Preparation of glass ionomer cement using N-acryloyl-substituted amino acid monomers--evaluation of physical properties.

OBJECTIVES: The objectives of this study were (1) to develop polyacid formulations through the incorporation of amino acid-derived monomers with carboxylic acid groups at various distances away from the polymer backbone to allow for greater flexibility, less rigid ionic cluster formation and improved solubility, and (2) to test selected physical and handling properties of experimental ionomers with a conventional glass ionomer as a control. METHODS: The polycarboxylic acids prepared and used in glass ionomer formulation in this study included N-acryloylglutamic acid (AGA) and N-acryloyl-6-aminocaproic acid (AACA)- modified acrylic acid- ++itaconic acid copolymers, where the acrylic acid:itaconic acid:amino acid monomers were combined in different proportions. The characterization and purity of the monomers were determined by FTIR and their melting points. The characterization of synthesized polymers included molecular weight and relative viscosity determinations. The compressive strengths, diametral tensile strengths, flexural strengths and fracture toughness of the experimental ionomers and a commercially available ionomer (control) were measured after storage in water, at 37 degrees C for 1 h or 7 d. The working times and setting times of the experimental ionomers were compared to the control specimens. Separate analysis of variance and Tukey's tests were used to study the statistical significance of the physical strength parameters as a function of materials and storage times. RESULTS: Significant increases (p< 0.001) in diametral tensile, compressive, flexural strengths and fracture toughness were observed in the AGA co-polymers, while significant increases were observed in diametral and flexural strengths in the AACA co-polymers compared to the control Fuji II. The working and setting times of all except one experimental ionomer studied were comparable to the controls. SIGNIFICANCE: The use of amino acid-modified acrylic monomers to produce water soluble copolymers of acrylic-itaconic acid offers a new route of discovery to produce chemical-cured glass ionomers with improved physical properties. The spacer chain length, the hydrophobicity of the chains, the molecular weight and viscosity of the polymer all played important roles in determining the physical properties of the material.

Acrylates↗
PubMed2001

Effects of habitual physical activity on the resting metabolic rates and body compositions of women aged 35 to 50 years.

OBJECTIVE: To examine the effect habitual physical activity has on resting metabolic rate (RMR) and body composition (fat-free mass[FFM], fat mass, and percent body fat) in active compared to sedentary adult women. DESIGN: RMR was measured (by indirect calorimetry) twice after a 12-hour fast at the same point of the menstrual cycle and 48 hours after exercise. FFM, fat mass and percent body fat were measured using whole body air displacement plethysmography. Energy intake and expenditure were determined using 7-day weighed-food records and activity logs. SUBJECTS: Healthy, weight-stable premenopausal women aged 35 to 50 years classified as either active (approximately 9 hours per week of physical activity for 10 or more years) (n= 18) or sedentary (approximately 1 hour per week of physical activity) (n= 14). STATISTICAL ANALYSES: Analysis of covariance was used to investigate differences in mean RMR (kcal/day) between the groups adjusted for FFM, and independent t tests were used to determine differences in demographic, energy expenditure, and diet variables. RESULTS: Percent body fat and fat mass were lower (P<.0005) and RMR (adjusted for FFM) was significantly higher in the active women (P=.045) compared with sedentary controls. In the active and sedentary groups respectively, mean adjusted RMR was 1,510 kcal/day and 1,443 kcal/day, body fat was 18.9% and 28.8%, and fat mass was 11.1 kg and 18.8 kg. Groups were similar in body mass, FFM, body mass index, and age. Mean energy balance appeared to be more negative in the active group (P=.0059) due to significantly higher mean self-reported energy expenditures (P=.0001) and similar mean self-reported energy intakes (P=.52) compared with sedentary controls. These data indicate that active women who participate in habitual physical activity can maintain lower body fat and a higher RMR than sedentary controls with similar body mass, FFM, and body mass index. APPLICATIONS/CONCLUSIONS: This research supports and emphasizes the benefits of habitual physical activity in maintaining RMR and lower body fat levels in middle-aged women.

Adipose Tissue↗
PubMed2002

External mechanical work versus oxidative energy consumption ratio during a basketball field test.

BACKGROUND: A field test consisting of 5 continuous runs at the maximum speed possible, playing the ball, starting from the centre line to the basket with a final shot, was studied in order to obtain an index of mechanical work efficiency in basketball players (micro-index=Jmec/Joxy) and evaluate the correlation between micro-index and velocity, acceleration, mechanical power and lactacid anaerobic capacity, respectively. METHODS: Eight male basketball players were studied; Jmec was the external mechanical work output obtained by means of a video image analysis software which gave the potential and the kinetic translational energies of athletes running and jumping and their velocity, acceleration and mechanical power. By means of a telemetric device (Kosmed K4), for measuring O2 consumption ( VO2), we obtained oxidative work (Joxy). By using this device we also assessed the excess of CO2, which was considered an index of lactacid anaerobic capacity. RESULTS: Non-parametric Spearman statistics revealed a significant correlation between mu index and mean velocity (p<0.01, r=0.90), acceleration (p<0.05, r=0.78), mechanical power (p<0.05 r=0.76) and CO2 excess (p<0.01, r=0.95). Consequently athletes who had the best index of mechanical efficiency also had the best biomechanical quality and the greatest lactacid anaerobic capacity. CONCLUSIONS: This study strongly supports the hypothesis that in basketball anaerobic capacity is important in achieving high values of speed, acceleration, mechanical power and endurance velocity.

Acceleration↗
PubMed2005

The effectiveness of a comprehensive work hardening program as measured by lifting capacity, pain scales, and depression scores.

OBJECTIVE: The purpose of this pilot study was to examine the effectiveness of a four-week work rehabilitation program. METHOD: Investigators conducted a retrospective chart review of 312 clients participating in the Work Evaluation and Rehabilitation Clinic (WERC) Program from 1994-2000. Only 196 charts were sufficiently complete to be included in the study. Of these 196 prospective clients, 166 began the WERC program and 141 completed the program and were included in the database. Data were gathered from the initial history and evaluations conducted upon admission to the program and from the final evaluation conducted at the time of discharge. Demographic information was recorded. Data from the following assessments were collected: pre- and post-scores for subjective measures of pain using the Oswestry Back Pain Scale and a self-report of pain, the Beck Depression Inventory, the Waddell Sign, and pre- and post-scores of several physical performance tasks. RESULTS: Statistically significant post-test improvements were shown in all six outcome measures used in this study. A decrease in pain correlated with the Floor to Waist Lift test and with the Carrying An Object 20 Feet test. The percentage increase in Waddell's Sign correlated with a decrease in the Carrying An Object 20 Feet test. The Floor to Waist Lift test correlated with the Carrying an Object 20 Feet test. The Oswestry Test correlated with the Beck Depression Scale. There was no significant relationship found between diagnosis of back injury and Waddell's Sign, between either the Waddell's Sign and the Oswestry, or the Waddell's Sign and depression. A regression analysis revealed diagnosis, level of education, gender, and pre-injury work load as significant predictors of improvements made during the work program. CONCLUSION: The program was shown to be effective as measured by the post-test improvements in all 6 performance tests. Although more research is warranted into the effectiveness of treatment for clients with chronic pain, it appears that there is a relationship between pain and physical performance and pain and depression in clients completing a work hardening program.

Adult↗
PubMed2005

Relationships of EMG to effort in the trunk under isometric conditions: force-increasing and decreasing effects and temporal delays.

BACKGROUND: Electromyograms are used in increasingly sophisticated biomechanical analyses to estimate forces within the trunk to prevent and evaluate painful spinal conditions. However, even under nominally isometric conditions the relationship between EMG and effort is complex. This study quantified influences of pulling direction, increasing versus decreasing effort and electromechanical delay on the EMG/effort relationships for principal lower trunk muscle groups in isometric pulling tasks, to determine whether the observed differences between increasing versus decreasing effort relationships were consistent with electromechanical delay or activation differences. METHODS: Twenty-three healthy subjects (15 male, 8 female; mean age 32 years; mean bodymass 74.5 kg) each stood in an apparatus to stabilize the pelvis and performed ramped isometric efforts with a harness around the thorax connected to each of a series of five anchor points on the wall, for angles of pull at each 45 degrees increment from 0 degrees to 180 degrees to the anterior direction. A load cell recorded the generated force for a 5 s timed increase up to a voluntary maximum, a 1s 'dwell', and a 5 s relaxation back to zero effort. EMG signals were recorded via electrodes (surface, except indwelling for multifidus) from right and left rectus abdominis, internal and external obliques, longissimus, iliocostalis and L2 and L4 level multifidus. EMG signals were rectified with a 250 ms root-mean-square moving average filter. Effort-increasing and effort-decreasing sections of recordings were analyzed separately. FINDINGS: The EMG/effort relationship had a statistically significantly greater gradient as the effort was increasing than when decreasing for 28 of 70 muscle-angle permutations. This difference in gradient was found to explain a significant part of the apparent lag between effort generated and EMG signal that averaged between 261 and 658 ms before and between 31 and 196 ms for different muscles after the slope difference was taken into account. INTERPRETATION: The findings were consistent with the notion that the motor unit recruitment differs in increasing versus decreasing isometric efforts, probably because of a small stretching of the muscle as its tension increases. The residual temporal delay was thought to represent electromechanical delay.

Adaptation, Physiological↗
PubMed1998

Test equating: what, why, how?

The purpose of this paper is to introduce test equating, including its concept, needs, and methods, to the field of physical education and exercise science. Both traditional and item response theory (IRT) equating methods, along with data collection designs, were described in detail, and the advantages and disadvantages of these methods were also introduced. In addition, equating errors and evaluation criteria, sample size, and related computer programs were introduced. Using an existing data set of sit-up tests, a test-equating application was illustrated through a step-by-step example. As a result, two sit-up tests were equated onto a common scale, and equating accuracy was evaluated using both equating and cross-validation samples. Finally, benefits and potential applications of test equating in assessing motor functions and skills, as well as future research challenges, were described.

Data Collection↗
PubMed2005

Quantum criticality and universal scaling of a quantum antiferromagnet.

Quantum effects dominate the behaviour of many diverse materials. Of particular current interest are those systems in the vicinity of a quantum critical point (QCP). Their physical properties are predicted to reflect those of the nearby QCP with universal features independent of the microscopic details. The prototypical QCP is the Luttinger liquid (LL), which is of relevance to many quasi-one-dimensional materials. The magnetic material KCuF3 realizes an array of weakly coupled spin chains (or LLs) and thus lies close to but not exactly at the LL quantum critical point. By using inelastic neutron scattering we have collected a complete data set of the magnetic correlations of KCuF3 as a function of momentum, energy and temperature. The LL description is found to be valid over an extensive range of these parameters, and departures from this behaviour at high and low energies and temperatures are identified and explained.

Magnetics↗
PubMed1989

Effects of pre-motion electromyographic silent period on dynamic force exertion during a rapid ballistic movement in man.

The effects of pre-motion silent period (PSP) on dynamic force exertion were studied in ten healthy subjects performing ballistic elbow extensions. The experiments were designed to evaluate the significance of mean differences between the averaged dynamic force curves of two groups: PSP-presence groups and PSP-absence groups. The presence of PSP was judged quantitatively and automatically by means of a newly developed method using statistical analysis. The results indicated that there were two effects of PSP on dynamic force exertion: one was a reducing effect, observed prior to the movement; the other was a reinforcing effect, observed in the first part of the ballistic movement. The duration of the reinforcement was significantly correlated with the duration of the reducing effect of PSP. The findings suggested that the reinforcement of dynamic force may be produced by the pre-stretch of agonistic muscles caused by prior force reduction due to PSP occurrence. The fact that PSP plays an important role in dynamic force exertion suggests that PSP may be incorporated in the central motor control system designed to interrupt the background activity, to stretch the agonist and to reinforce the dynamic force.

Adult↗
PubMed1982

A statistical analysis of the spectral moments used in EMG tests of endurance.

EMG and bandlimited noise (BLN) signals of comparable spectra were processed to compute the centroid and median frequencies and the high/low ratio for different record lengths, signal amplitudes, and noise bandwidths. The spectral moments of EMG and BLN showed similar statistical properties, independent of record length and amplitude. The signal-to-noise ratios of the moments increased with record length. Relatively short records were sufficient to obtain low coefficients of variations especially for the centroid, which was the most stable and sensitive to changes in the underlying spectra. The high/low ratio was the least stable moment. A change of 10 and 3.9% in the centroid over successive records of overall duration of 8 and 10 s, respectively, was just sufficient to detect a spectral shift at the P less than 0.05 level. The equivalent percents for the high/low ratio were 66 and 32.5, respectively. These thresholds of significance were related to time constants of equivalent exponential trends in the spectra used to study fatigue. This relationship makes the results of the present study applicable to a wide variety of EMG tests of endurance.

Electromyography↗
PubMed1992

Joint impairment and hand function in the elderly.

OBJECTIVE: To test the contribution of joint impairment to observed hand function (grip strength and Williams Test) in the elderly, using a multivariate model. DESIGN: Cross-sectional observational data (baseline data from an ongoing longitudinal study). SUBJECTS: Five hundred forty-one persons over age 60, including continuing care retirement community (n = 222), homebound (n = 72), and ambulatory (n = 247) respondents. Mean age at assessment 76.7, (SD = 9.0). MEASUREMENT: Independent variables included sociodemographics, physician measures of upper joint impairment, an index of comorbidities derived from physical examination or chart abstract, self-assessed arthritis pain, depression, and anxiety. The dependent variables included grip strength and a modified Williams Test [Williams Test (M)]. MAIN RESULTS: The multiple regression explained 59% (Adjusted R2 = .59) of the variance in grip strength, with joint impairment accounting for a change in R2 of .07. Upper joint impairment and grip strength accounted for 3% and 5%, respectively, of the variance in the Williams Test (M) (total amount of explained variance = 45%). CONCLUSIONS: Demographics explain most of the variance in grip strength and performance on the Williams Test (M). Controlling for demographics, musculoskeletal disease represented by joint impairment is associated with diminished grip strength. Reduced grip strength is associated with poorer performance on the Williams Test (M).

Activities of Daily Living↗
PubMed2005

mus309 mutation, defective in DNA double-strand break repair, affects intergenic but not intragenic meiotic recombination in Drosophila melanogaster.

The effect was investigated of the hypomorphic DNA double-strand break repair, notably synthesis-dependent strand annealing, deficient mutation mus309 on the third chromosome of Drosophila melanogaster on intergenic and intragenic meiotic recombination in the X chromosome. The results showed that the mutation significantly increases the frequency of intergenic crossing over in two of three gene intervals of the X chromosome studied. Interestingly the increase was most prevalent in the tip of the X chromosome where crossovers normally are least frequent per physical map unit length. In particular crossing over interference was also affected, indicating that the effect of the mus309 mutation involves preconditions of crossing over but not the event of crossing over itself. On the other hand, the results also show that most probably the mutation does not have any effect on intragenic recombination, i.e. gene conversion. These results are fully consistent with the present molecular models of meiotic crossing over initiated by double-strand breaks of DNA followed by formation of a single-end-invasion intermediate, or D-loop, which is subsequently processed to generate either crossover or non-crossover products involving formation of a double Holliday junction. In particular the results suggest that the mus309 gene is involved in resolution of the D-loop, thereby affecting the choice between double-strand-break repair (DSBR) and synthesis-dependent strand annealing (SDSA) pathways of meiotic recombination.

Animals↗
PubMed1998

Effects of HEMA on water evaporation from water-HEMA mixtures.

OBJECTIVES: The aims of this research were: (1) to determine the relative rates of evaporation of water and HEMA, and (2) to determine the effects of increasing concentrations of HEMA on the rate of evaporation of water from water and HEMA mixtures. METHODS: Ten microliters of each solution (100% H2O, 75% H2O-25% HEMA, 50% H2O-50% HEMA, 25% HEMA, 100% HEMA) were placed on the pan of a thermogravimetric analysis instrument held at 37 degrees C. The rate of spontaneous weight loss was measured as a function of time and relative humidity (RH) and compared statistically using ANOVA and Scheffé F test. RESULTS: The rate of evaporation of pure water was 32-fold higher than that of 100% HEMA. Addition of HEMA to water lowered the rate of evaporation of water from the water-HEMA mixtures in a manner that was proportional to its effect on lowering the vapor pressure of water (p < 0.05 comparing 50% HEMA with 75% HEMA). The rate of evaporation of water from water-HEMA mixtures was higher (p < 0.05) when the ambient gas was at 0% RH than when it was at 51% RH. SIGNIFICANCE: The results indicate that as water evaporates from water-HEMA mixtures, the concentration of HEMA rises because it is relatively non-volatile. This rise in HEMA concentration lowers the vapor pressure of water making it more difficult to remove the last amounts of water. This residual water may interfere with polymerization of adhesive monomers, thereby lowering the quality of the hybrid layer.

Analysis of Variance↗
PubMed2002

The development and testing of APTA Clinical Performance Instruments. American Physical Therapy Association.

BACKGROUND AND PURPOSE: The purposes of this article are to describe the process of developing the physical therapist (PT) and physical therapist assistant (PTA) Clinical Performance Instruments (CPIs) and to present the available information on the psychometric properties of each instrument. SUBJECTS: Two hundred seventeen PTA students and 282 PT students participated in the pilot studies of the CPIs, and 181 PTA students and 319 PT students participated in field studies. METHODS: To construct each instrument, content was first gathered from a variety of instruments and American Physical Therapy Association documents related to PT and PTA practice and education. Data compiled during the pilot and field study phases of the project led to the construction of the fourth (final) versions of the CPIs, which although not studied are currently in use. RESULTS: Intraclass correlation coefficients (ICC [2,1]) measuring the interrater reliability of the CPI total score were good (ICC=.87) for the PT total score and moderate (ICC=.77) for the PTA total score. Construct validity was supported by the substantial differences in mean CPI score for students completing first as compared with final clinical experiences, by the correlation between CPI item scores and total days of clinical experience, and by the lack of correlation with the Social Skills Inventory score. DISCUSSION AND CONCLUSION: Sale of the fourth (final) versions of the PT CPI occurred in November 1997 and of the PTA CPI in March 1998. Data based on psychometric evaluation of the final version have not yet been collected and reported. In the task force's opinion, the third drafts can provide reliable and valid measurements of PT or PTA student clinical performance. The fourth versions were based on this iteration.

Data Interpretation, Statistical↗
PubMed2006

Hemorheologic effects of low intensity endurance training in sedentary patients suffering from the metabolic syndrome.

Hemorheologic effects of exercise training ("hemorheologic fitness") are very different according to the mode and the intensity of this training. We previously reported that low intensity endurance training in sedentary patients suffering from the metabolic syndrome sumultaneously improved blood rheology, body composition and lipid oxidation at exercise. We aimed at analyzing the link among these improvements in 24 patients submitted to a 2 months targeted training designed for increasing exercise lipid oxidation. Variations of whole blood viscosity at high shear rate (etab 1000 s(-1)) were explained here by two statistically independent determinants: hematocrit and red cell rigidity. etab decreased in 16 subjects, but increased in 8, due to a rise in hematocrit. Changes in RBC rigidity appeared to reflect weight loss and decrease in LDL cholesterol. Plasma viscosity was related to cholesterol and its training-induced changes are related to those of VO2 max ) but not to lipid oxidation. Red cell aggregability (Myrenne) reflected both the circulating lipids (Chol, HDL and LDL) and the ability to oxidize lipids at exercise. Factors associated to a post-training decrease in aggregability (M1) were weight loss and more precisely decrease in fat mass, improvement in lipid oxidation, rise in HDL-Chol, and decrease in fibrinogen. On the whole the major determinant of hemorheologic improvement was an increase in cardiorespiratory fitness (VO2 max ), correlated with a decrease in plasma viscosity, rather than an improvement in lipid metabolism, although RBC aggregability and deformability exhibited clear relationships with lipid metabolism. For which reason Hct increased in 30% of the patients during this kind of training remains unclear.

Aged↗
PubMed2004

Comparison of risk factors for colon and rectal cancer.

Predictors of colorectal cancer have been extensively studied with some evidence suggesting that risk factors vary by subsite. Using data from 2 prospective cohort studies, we examined established risk factors to determine whether they were differentially associated with colon and rectal cancer. Our study population included 87,733 women from the Nurses' Health Study (NHS) and 46,632 men from the Health Professionals Follow Up Study (HPFS). Exposure information was collected via biennial questionnaires (dietary variables were collected every 4 years). During the follow-up period (NHS: 1980 to May 31, 2000; HPFS: 1986 to January 31, 2000), we identified 1,139 cases of colon cancer and 339 cases of rectal cancer. We used pooled logistic regression to estimate multivariate relative risks for the 2 outcomes separately and then used polytomous logistic regression to compare these estimates. In the combined cohort, age, gender, family history of colon or rectal cancer, height, body mass index, physical activity, folate, intake of beef, pork or lamb as a main dish, intake of processed meat and alcohol were significantly associated with colon cancer risk. However, only age and sex were associated with rectal cancer. In a stepwise polytomous logistic regression procedure, family history and physical activity were associated with statistically significant different relative risks of colon and rectal cancer. Our findings support previous suggestions that family history and physical activity are not strong contributors to the etiology of rectal cancer. Future investigations of colon or rectal cancer should take into consideration risk factor differences by subsite.

Adult↗
PubMed2003

[Compliance with gluten free diet, physical development and bone mineral status in patients with celiac disease].

OBJECTIVES: The aim of the study was the assessment of the influence of a gluten free diet on physical development and bone mineral density (BMD) in patients with celiac disease. MATERIALS & METHODS: 59 patients (40 girls, 19 boys) aged 10-20 years with celiac disease, diagnosed according to ESPGAN criteria were included in the study. Patients were divided in 3 groups: 1--strict gluten free diet, II--not entirely compliant i.e. faults in gluten free diet 1-2 times per week, III--gluten free diet not followed or frequent faults. Daily calcium (Ca) intake and physical activity was assessed. BMD of the lumbar spine L2-L4 was measured by dual-energy-X-ray absorptiometry with LUNAR DPX-IQ. Physical development was assessed by anthropometric measurements: growth and weight. RESULTS: Gluten free diet was strictly followed by 16 (27%) patients (group I), group II consisted of 23 (39%) patients. Diet was not followed by 20 (34%) patients. Thirty five (59%) patients had low Ca intake and they made up the majority of the patients in every group. High physical activity declared 35 (59%) patients. No statistically significant differences in BMD were found between group I and II. BMD was lower in group III in comparison to group I (p = 0.01) and group II (p = 0.003). BMD was higher in patients with high Ca intake (p = 0.002). Physical activity had no significant influence on BMD. There was no statistically significant difference in physical development between groups. CONCLUSIONS: Majority of the patients with celiac disease did not strictly follow gluten free diet. Poor compliance to the diet had no significant influence on physical development. BMD was lower in patients who were not compliant to the gluten free diet, occasional faults in the diet had no influence on the BMD.

Absorptiometry, Photon↗
PubMed2003

Sport and home physical activity are independently associated with bone density.

PURPOSE: To study the relations between four domains of physical activity-sport, home, work, and active living-and bone mineral density (BMD). METHODS: Baseline data from African-American (N = 544), Caucasian (N= 1044), Chinese (N= 230), and Japanese (N= 239) participants, aged 42-52 yr, from the study of Women's Health Across the Nation were analyzed. BMD was measured with Hologic 2000 or 4500A densitometers. Physical activity was assessed with the Kaiser Physical Activity Scale, which rates each domain of activity between 1 (low) and 5 (high). Multiply adjusted linear regression models were used to estimate the relations between each activity domain and BMD. RESULTS: The mean and median values of sport, home, work, and active living each approximated the midpoint of the scale and did not differ substantially among ethnic groups. Scores for each domain of activity were not highly correlated, with r values ranging between -0.03 and 0.33. Independent of age, body mass index, ethnic group, alcohol use, dietary calcium, smoking, menopause status, SWAN site, and other domains of physical activity, higher sport activity was statistically significantly associated with greater BMD at the lumbar spine (P= 0.008), femoral neck (P= 0.0002), and total hip (P< 0.0001). More home physical activity was associated with higher BMD at the spine (P= 0.049) and femoral neck (P= 0.008). Neither work physical activity nor active living was related to BMD at any bone site. CONCLUSIONS: These results highlight the need to consider domain-specific physical activity in relation to health outcomes in women.

Adult↗