Correlation between maximum bite force and facial morphology in children

The correlation between maximum bite force and facial morphology was studied in 54 boys, 8 to 16 years old, and 66 girls, 7 to 17 years old. Bite force was measured at the first molars with a miniature bite force recorder. Facial morphology was evaluated on profile cephalograms. In addition, the number of teeth in contact in the intercuspal position was recorded with occlusal foils. In the girls, maximum bite force was correlated with the inclination of the mandible, the size of the gonial angle, and the ratio between posterior and anterior face heights. The correlations implied a large bite force with a small mandibular inclination and gonial angle, a large posterior face height in relation to the anterior face height, and a small bite force with the opposite facial characteristics. These correlations were nonexistent or weaker in boys. In both sexes, bite force was correlated with the number of occlusal contacts. Elimination of the influence of age and occlusal contact in the group of girls by the use of partial correlations reduced the correlation between bite force and facial morphology. A significant correlation with the size of the gonial angle remained, however, and the correlation with mandibular inclination was close to significance. In addition to the correlations found with facial morphology, the study clearly demonstrated the need to take gender and occlusal contacts into consideration in future studies of masticatory muscle function and strength in relation to facial morphology.     

Racial differences in muscle strength in disabled older women

This study examines racial differences in muscle strength, and associations of muscle strength to level of physical activity and severity of disability, among a community sample of 254 black and 665 white, moderately to severely disabled women aged 65 and older. Potential confounders that were adjusted for in the models included age, body weight and height, joint pain, number of chronic conditions, and socioeconomic status. Hand grip, hip flexion, and knee extension forces were measured using portable hand-held dynamometers in the participants' homes. Hand grip strength was measured as the maximal isometric force. Hip flexion and knee extension forces were measured as the greatest force the tester had to apply to break the isometric contraction. A declining strength gradient was observed with increasing severity of disability and for decreasing level of physical activity in both races. At equal levels of disability or physical activity, blacks had better hand grip and hip flexion strength, but knee extension strength did not differ by race. The greater hand grip and hip flexion strength found in black women may be related to their greater muscle mass and known racial differences in body dimensions. No consistent racial differences were observed in the relationship between physical activity and muscle strength, or muscle strength and disability, suggesting that the role of muscle strength in the disablement process does not differ between races. Physical activity and exercise programs may be feasible ways to prevent worsening of disability in blacks and whites.     

Associations between body condition and disease in cats

OBJECTIVE: To determine the association between body condition and disease in cats. DESIGN: Prospective study. SAMPLE POPULATION: Information on 1,457 cats without major illnesses from 27 veterinary hospitals in the northeastern United States. PROCEDURE: Cats that had body conditions determined from 1991 to 1992, using a set of 6 body condition silhouettes, had their health experiences and body conditions assessed for the subsequent 4.5 years. Cats were described by the following 6 body conditions: cachectic, lean, optimally lean, optimal weight, heavy, and obese. Data obtained from medical records and owner interviews were collected, using standard forms. Associations between body condition and specific diseases were analyzed. Findings in cats with body conditions other than optimal were compared with findings in cats with optimal body condition. RESULTS: Compared with optimal weight cats, heavy cats were 2.9 times as likely to be taken to veterinarians because of lameness not associated with cat bite abscesses. Obese cats were also 3.9 times as likely to develop diabetes mellitus, 2.3 times as likely to develop nonallergic skin conditions, and 4.9 times as likely to develop lameness requiring veterinary care. Cats considered thin (cachectic and lean) were 1.7 times as likely to be presented to veterinary hospitals for diarrhea. CLINICAL IMPLICATIONS: Results of this study substantiate reports of health risks associated with excess body weight in cats. Efforts to reduce weight in heavy and obese cats can lead to reduced risks of diabetes mellitus, lameness (presumably related to osteoarthritis and soft-tissue injuries), and skin problems unrelated to allergies. Cachectic and lean cats are more likely to have diarrhea that is not associated with a definitive diagnosis.     

Pressure-flow studies: an evaluation of within-testing reproducibility--validity of the measured parameters

Growth and maturation during adolescence has not been well described in rural African populations, although it may represent the missing link between high levels of preschool stunting and nearly 'normal' adult heights. In 1995 the homes of subjects aged 10.3-17.5 years, living in a rural area of Senegal, were visited, and all adolescents present, 1527 boys and 1126 girls, were included in the analysis. A number of girls were absent because they worked in the capital city Dakar. Resident girls (n = 705) had significantly higher means than boys for all anthropometric variables (weight, body mass index, arm circumference and muscle arm circumference, triceps and subscapular skinfolds), except for height and head circumference. Girls who had just returned from seasonal migration to Dakar (n = 415) were, on average, 2 kg heavier, but not taller, than resident girls (p < 0.0001). The girls fell off in height from 11 to 13 years compared to the NCHS reference and then 'caught up' until the age of 17, while boys fell off during the entire age span. Mean age at menarche was estimated at 16.1 years (95% fiducial CI: 15.8-16.4) from status quo data by probit analysis. No significant difference was found between residents and migrants. Postmenarcheal girls had better nutritional status than premenarcheal girls in terms of height, weight, body mass index, percentage body fat and arm muscle circumference (p < 0.0001). In conclusion, puberty, as assessed by age at menarche, is delayed by about 3 years in this population, probably due to malnutrition.     

Urban-rural variations in health in The Netherlands: does selective migration play a part?

In the present study, we examined the genotypes distribution of Pvu II estrogen receptor (ER) gene polymorphism and its association to bone mass in Thai females. Subjects consisted of 134 Thai females 54 of whom were premenopausal and 80 were postmenopausal. Pvu II ER gene polymorphism was determined by PCR-RFLP. Capital P represents the absence of the restriction site while small p indicates the presence of the restriction site. Forty nine (36.6%) of the subjects had pp genotype, while 59 (44.0%) had Pp genotype and 26 (19.4%) had PP genotype. There was no significant difference in age, body weight, height and calcium intake in premenopausal women with different genotypes. The results including years since menopause were similar in postmenopausal women. When including ER gene genotypes, age, body weight, height and dietary calcium intake in a stepwise multiple regression model, it was found that besides body weight ER gene polymorphism was associated with bone mineral density (BMD) at AP spine (p < 0.05), lateral spine (p < 0.05) femoral neck (p < 0.05) and femoral trochanter (p < 0.05) with the pp genotype having the least BMD. ER gene polymorphism was the only factor associated with BMD at Ward's triangle, (p < 0.05) while only body weight was associated with BMD at distal and mid radius. There was no difference in serum intact osteocalcin (OC) concentrations among subjects with different genotypes. ER gene polymorphism was not related to BMD in postmenopausal women at any skeletal site. Similarly, serum intact OC levels were not different among postmenopausal women with different genotypes. We concluded that Pvu II estrogen receptor gene polymorphism is associated with bone mineral density in premenopausal women but not in postmenopausal women. Estrogen receptor gene polymorphism may have a modulatory role in calcium and bone metabolism during adolescence and young adulthood.     

Gender differences in body fat content are present well before puberty

To determine whether gender differences in body fat could be detected in prepubertal children using dual energy X-ray absorptiometry (DEXA), body composition was measured in 20 healthy boys aged 3-8 y matched for age, height and weight with 20 healthy girls. Although boys and girls did not differ in age, height, weight, body mass index (BMI) or bone mineral content, the boys had a lower percentage of body fat (13.5 +/- 5.1 vs 20.4 +/- 6.1%, P < 0.01), a lower fat mass (3.2 +/- 2.0 vs 4.9 +/- 3.1 kg, P < 0.01), and a higher bone-free lean tissue mass (18.6 +/- 4.3 vs 17.0 +/- 3.5 kg, P < 0.01) than the girls. Girls had approximately 50% more body fat than the boys. This is the first DEXA study to show that boys aged 3-8 y have less body fat than girls of similar age, height and weight. Thus, this technology demonstrates that significant gender differences in body composition are evident, well before the onset of puberty.     

Calf and disease factors affecting growth in female Holstein calves in Florida, USA

A prospective cohort study was undertaken to determine calf-level factors that affect performance (growth) between birth and 14 months of age in a convenience sample of approximately 3300 female Holstein calves born in 1991 on two large Florida dairy farms. Data collected on each calf at birth included farm of origin, birth date, weight, height at the pelvis, and serum total protein (a measure of colostral immunoglobulin absorption). Birth season was dichotomized into summer and winter using meteorological data collected by University of Florida Agricultural Research Stations. Data collected at approximately 6 and 14 months of age included age, weight, height at the pelvis, and height at the withers. Growth in weight and stature (height) was calculated for each growth period; growth period 1 (GP1) = birth to 6 months, and growth period 2 (GP2) = 6 to 14 months. Health data collected included data of initial treatment and number of treatments for the diseases diarrhea, omphalitis, septicemia, pneumonia and keratoconjunctivitis. After adjusting for disease occurrence, passive transfer of colostral immunoglobulins had no significant effect on body weight gain or pelvic height growth. Season of birth and occurrence of diarrhea, septicemia and respiratory disease were significant variables decreasing heifer growth (height and weight) in GP1. These variables plus farm, birth weight and exact age when '6 month' data were collected explained 20% and 31% of the variation in body weight gain and pelvic height growth, respectively, in GP1. The number of days treated for pneumonia before 6 months of age significantly decreased average daily weight gain in GP2 (P < 0.025), but did not affect stature growth. Treatment for pneumonia after 6 months of age did not significantly affect weight or height gain after age 6 months. Neither omphalitis nor keratoconjunctivitis explained variability in growth in either of the growth periods.     

Effect of somatic parameters on Frank's electrocardiogram in childhood

Correlations were computed between 123 different electrocardiographic variables and constitutional parameters of 179 children aged seven to fourteen years using the Frank system. The constitutional parameters consisted of age, body weight, height, chest circumference and deviation from ideal weight related to height. The corrected orthogonal Ecg was automatically measured by a CD 3300 computer using the program of Pipberger. The results show that the greatest number of statistically significant correlations exist between Ecg variables and body height. In contrast to expectations, age takes only the second rank. Normal values of the Frank Ecg should be related to height not to age, at least in the studied age group.     

Anticipatory load torques produced by voluntary movements.

The stability of an object held between the finger and thumb depends on friction developed by grip force, normal to the contact surfaces, to overcome tangential load force. Previous research has shown that in lifting an object, grip force rises with the increase in gravitational load force as the hand takes the weight and that in moving an object, grip force is adjusted to meet movement-induced inertial load force. Those results demonstrated the anticipatory nature of coordination of grip force with load force. Whether grip force anticipates load torque was studied in this research. When participants were constrained to use grasp points where the grasp axis was manifestly distant from object center of mass, it was found that they made grip force adjustments in anticipation of load torques that tended to destabilize an object as a result of lifting or moving it. These adjustments imply use of information about object center of mass in movement planning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Total body studies in normal British women using dual energy X-ray absorptiometry

We report dual energy X-ray absorptiometry (DXA) studies of total body bone mineral and body composition performed in 111 normal caucasian women (aged 42-61). Conventional DXA scans of the lumbar spine and femoral neck were also obtained and each woman completed a detailed questionnaire. Significant correlations were found between total body BMD and BMD in the lumbar spine (r = 0.76) and femoral neck (r = 0.72). We present reference range data for BMD in the total body and in seven subregions of the skeleton. Multiple linear regressions of total body BMD and BMC on weight, height and age showed that the inclusion of height compared with weight and age alone was not statistically significant. The dependence of total body BMD on weight and age was: total body BMD (g cm-2) = 1.043 + 0.0042 x weight (kg) - 0.0039 x age (years) (R = 0.46, SEE = 0.074 g cm2). Body mass derived from DXA scans correlated well with weight measured on scales (r = 0.996, SEE = 0.77 kg). Body composition measurements agreed closely with % body fat estimated from skinfold measurements (r = 0.93), body fat mass estimated from a predictive equation based on weight, height and age (r = 0.91) and % body fat estimated from a predictive equation based on body mass index (r = 0.76). Study precision gave coefficients of variation of 0.6% for total body BMD and 0.7% for % body fat.     

Prenatal monitoring of ornithine transcarbamoylase deficiency in two families by DNA analysis

This study examined the variation in weight, height and body mass index of 1048 mothers living in a rural area of Bangladesh in relation to age, education, number of previous pregnancies, number of dead children, religion, family type, family size, and amount of land owned by the household. Multiple regression analysis revealed a positive relationship of education with all three variables. Moslem mothers were on average in better condition than Hindus. The number of dead children showed a negative relationship with height, weight and body mass index.     

Size at birth, maternal nutritional status in pregnancy, and blood pressure at age 17: population based analysis

OBJECTIVE: To assess the effect of size at birth, maternal nutrition, and body mass index on blood pressure in late adolescence. DESIGN: Population based analysis of birth weight corrected for gestational age, mother's weight before pregnancy and weight gain in pregnancy, obtained from the Jerusalem perinatal study, and blood pressure and body mass index at age 17, available from military draft records. SETTING: Jerusalem, Israel. SUBJECTS: 10,883 subjects (6684 men and 4199 women) born in Jerusalem during 1974-6 and subsequently drafted to the army. MAIN OUTCOME MEASURES: Systolic and diastolic blood pressures measured at age 17 and their correlation with birth weight, size at birth, mother's body mass index and weight gain during pregnancy, and height and weight at age 17. RESULTS: Systolic and diastolic blood pressures were significantly and positively correlated with body weight, height, body mass index at age 17, and with mother's body weight and body mass index before pregnancy, but not with birth weight or mother's weight gain in pregnancy. CONCLUSION: Variables reflecting poor intrauterine nutrition, including low maternal body mass index before pregnancy, poor maternal weight gain in pregnancy, and being born small for gestational age, were not associated with a higher blood pressure in late adolescence.     

Body composition in normal black women: the four-compartment model

The four-compartment model of body composition was studied in 112 healthy black women to develop normative data to be used to assess deviations in illness. Each compartment was measured by an independent method: tritiated water dilution, prompt-gamma neutron activation analysis (for nitrogen), inelastic neutron scattering (for carbon) and dual energy x-ray absorptiometry (for calcium). The mean age of the population was 43.2 years. Race was self-declared. The mean values for the four compartments were [kg SE] protein: 9.6 (0.07); mineral 3.0 (0.03); fat 24.2 (0.70); and water 33.1 (0.29). Each of the compartments changed significantly with age (P < .0001). There were declines in total body water, mineral, and protein, whereas fat increased linearly with age. Linear regressions performed on pre- and postmenopausal women showed a significant difference only for the mineral compartment. Various models were fit to the data to adjust for body size and age. The equation y = age + height + weight fits the data as well as the other models. Equations and graphs were developed to assess each compartment using this linear model and may be used to assess the body composition status of healthy and ill black women. Although black women tended to be heavier than white women, after controlling for differences in body weight (and age) black women had a greater mass of protein, mineral, and water and a similar fat store. These differences, while statistically significant, were not of great magnitude. This was a cross-sectional study and suspected trends with aging must be confirmed by a longitudinal study.     

Wrist action affects precision grip force

When moving objects with a precision grip, fingertip forces normal to the object surface (grip force) change in parallel with forces tangential to the object (load force). We investigated whether voluntary wrist actions can affect grip force independent of load force, because the extrinsic finger muscles cross the wrist. Grip force increased with wrist angular speed during wrist motion in the horizontal plane, and was much larger than the increased tangential load at the fingertips or the reaction forces from linear acceleration of the test object. During wrist flexion the index finger muscles in the hand and forearm increased myoelectric activity; during wrist extension this myoelectric activity increased little, or decreased for some subjects. The grip force maxima coincided with wrist acceleration maxima, and grip force remained elevated when subjects held the wrist in extreme flexion or extension. Likewise, during isometric wrist actions the grip force increased even though the fingertip loads remained constant. A grip force "pulse" developed that increased with wrist force rate, followed by a static grip force while the wrist force was sustained. Subjects could not suppress the grip force pulse when provided visual feedback of their grip force. We conclude that the extrinsic hand muscles can be recruited to assist the intended wrist action, yielding higher grip-load ratios than those employed with the wrist at rest. This added drive to hand muscles overcame any loss in muscle force while the extrinsic finger flexors shortened during wrist flexion motion. During wrist extension motion grip force increases apparently occurred from eccentric contraction of the extrinsic finger flexors. The coactivation of hand closing muscles with other wrist muscles also may result in part from a general motor facilitation, because grip force increased during isometric knee extension. However, these increases were related weakly to the knee force. The observed muscle coactivation, from all sources, may contribute to grasp stability. For example, when transporting grasped objects, upper limb accelerations simultaneously produce inertial torques at the wrist that must be resisted, and inertial loads at the fingertips from the object that must be offset by increased grip force. The muscle coactivation described here would cause similarly timed pulses in the wrist force and grip force. However, grip-load coupling from this mechanism would not contribute much to grasp stability when small wrist forces are required, such as for slow movements or when the object's total resistive load is small.     

The Troms? Study: body height, body mass index and fractures

Tall persons suffer more hip fractures than shorter persons, and high body mass index is associated with fewer hip and forearm fractures. We have studied the association between body height, body mass index and all non-vertebral fractures in a large, prospective, population-based study. The middle-aged population of Troms?, Norway, was invited to surveys in 1979/80, 1986/87 and 1994/95 (The Troms? Study). Of 16,676 invited to the first two surveys, 12,270 attended both times (74%). Height and weight were measured without shoes at the surveys, and all non-vertebral fractures in the period 1988-1995 were registered (922 persons with fractures) and verified by radiography. The risk of a low-energy fracture was found to be positively associated with increasing body height and with decreasing body mass index. Furthermore, men who had gained weight had a lower risk of hip fractures, and women who had gained weight had a lower risk of fractures in the lower extremities. High body height is thus a risk factor for fractures, and 1 in 4 low-energy fractures among women today might be ascribed to the increase in average stature since the turn of the century. Low body mass index is associated with a higher risk of fractures, but the association is probably too weak to have any clinical relevance in this age category.     

Effect of age on pentylenetetrazol-kindling and kindling-induced impairments of learning performance

PURPOSE: To assess the effects of age, gender, race, and body size on infrarenal aortic diameter (IAD) and to determine expected values for IAD on the basis of these factors. METHODS: Veterans aged 50 to 79 years at 15 Department of Veterans Affairs medical centers were invited to undergo ultrasound measurement of IAD and complete a pre-screening questionnaire. We report here on 69,905 subjects who had no previous history of abdominal aortic aneurysm (AAA) and no ultrasound evidence of AAA (defined as IAD > or = 3.0 cm). RESULTS: Although age, gender, black race, height, weight, body mass index, and body surface area were associated with IAD by multivariate linear regression (all p < 0.001), the effects were small. Female sex was associated with a 0.14 cm reduction in IAD and black race with a 0.01 cm increase in IAD. A 0.1 cm change in IAD was associated with large changes in the independent variables: 29 years in age, 19 cm or 40 cm in height, 35 kg in weight, 11 kg/m2 in body mass index, and 0.35 m2 in body surface area. Nearly all height-weight groups were within 0.1 cm of the gender means, and the unadjusted gender means differed by only 0.23 cm. The variation among medical centers had more influence on IAD than did the combination of age, gender, race, and body size. CONCLUSIONS: Age, gender, race, and body size have statistically significant but small effects on IAD. Use of these parameters to define AAA may not offer sufficient advantage over simpler definitions (such as an IAD > or = 3.0 cm) to be warranted.     

Doing more with less

We performed spirometry on 333 healthy Bhutanese men and women at Thimpu. Prediction equations were derived using age and height as regression coefficients. Age had a significant negative correlation while both height and weight had positive linear correlation with spirometric indices. The relationship of weight with FVC was explained largely on the basis of the "muscularity" effect of weight. Bhutanese have lower ventilatory parameters than the Europeans and the North Indians. The difference is likely to be ethnic in origin.     

型钢矫直机自然咬入条件分析及安装高度的确定

矫直咬入影响轧件能否顺利进入矫直机并矫直。本文分析了钢板矫直时的力学模型,得到矫直自然咬入条件,并由矫直时超前接触现象建立了稳定矫直时的力学平衡方程。针对型钢矫直特点,指出型钢矫直咬入条件同钢板类似。结合型钢矫直机的工况,给出矫直多品种多规格型钢时矫直机最优安装高度的计算方法。应用实例表明,矫直自然咬入条件能够反映矫直咬入实际情况,指导矫直机的安装。     

False-positive diagnosis of adrenal pheochromocytoma on iodine-123-MIBG scan

OBJECTIVE: To study the relationship between percent body fat and body mass index (BMI) in two different ethnic groups (Indonesians and Caucasians) in order to evaluate the validity of the BMI cut-off points for obesity. DESIGN: Cross-sectional study. SUBJECTS: Not specially selected populations living in southern Sumatra (Palembang, Indonesia) and Caucasian Dutch living in Wageningen. MEASUREMENTS: Body weight, body height, body fat by deuterium oxide dilution and skinfold thickness. RESULTS: Body fat could be well predicted by body mass index (BMI) and sex in the Indonesians and by BMI, sex and age in the Dutch with a prediction error of 3.6 and 3.3% for the two populations respectively. Although the body mass index in the Indonesian group was about 2 kg/m2 lower compared to the Dutch, the amount of body fat was 3% points higher. Because of small differences between the groups in age, weight and height the differences in body fat were corrected for this (ANOVA). Indonesians having the same weight, height, age and sex have generally 4.8% points more body fat compared to Dutch. Indonesians having the same % BF, age and sex have generally a 2.9 kg/m2 lower BMI compared to the Dutch. CONCLUSIONS: The results show that the relationship between % BF and BMI is different between Indonesians and Dutch Caucasians. If obesity is regarded as an excess of body fat and not as an excess of weight (increased BMI), the cut-off points for obesity in Indonesia based on the BMI should be 27 kg/m2 instead of 30 kg/m2.