Effect of diet, sex and age on fatty acid metabolism in broiler chickens : n-3 and n-6 PUFA

The PUFA metabolism in broiler chicken was studied through the whole body fatty acid balance method. Four dietary lipid sources (palm fat, Palm; soyabean oil, Soya; linseed oil, Lin; fish oil, Fish) were added at 3% to a basal diet containing 5% palm fat. Diets were fed to female and male birds from day 1 to either day 21 or day 42 of age. Birds fed the Lin diet showed a significantly higher 18 : 2n-6 accumulation compared with the other diets (85·2 v. 73·6% of net intake), whereas diet did not affect 18 : 3n-3 accumulation (mean 63% of net intake). Bioconversion of 18 : 2n-6 significantly decreased in the order Palm.> Lin > Soya > Fish (4·7, 3·9, 3·4 and 1% of net intake, respectively). The 18 : 3n-3 bioconversion on the Palm and Soya diets was similar and significantly higher than in broilers on the Lin diet (9·1 v. 5·8% of net intake). The β-oxidation of 18 : 2n-6 was significantly lower on the Lin diet than on the other diets (10·8 v. 23·3% of net intake), whereasβ-oxidation of 18 : 3n-3 was significantly higher on the Fish diet than on the other diets (41·5 v. 27·3% of net intake). Feeding fish oil suppressed apparent elongase and desaturase activity, whereas a higher dietary supply of 18 : 3n-3 and 18 : 2n-6 enhanced apparent elongation and desaturation activity on the PUFA involved in the n-3 and n-6 pathway, respectively. Accumulation of 18 : 2n-6 and 18 : 3n-3 increased andβ -oxidation decreased with age. Sex had a marginal effect on the PUFA metabolism.

Relationship between indices of adiposity obtained by peripheral quantitative computed tomography and dual-energy X-ray absorptiometry in pre-pubertal children

Background/Aim: The study investigated the relationship between indices of adiposity measured by peripheral quantitative computed tomography (pQCT) and dual-energy X-ray absorptiometry (DXA) in pre-pubertal children.

Subjects and methods: DXA-derived per cent body fat (%BF) was measured in 284 boys and 288 girls, aged 7–10 years. Cross-sections of the forearm (n=427) and lower leg (n=560) were obtained by pQCT to measure total cross-sectional area of the limb (Total CSA), Muscle CSA, Fat CSA, %Fat CSA (Fat CSA/Total CSA×100) and muscle density.

Results: Peripheral QCT-derived %Fat CSA in the forearm and lower leg correlated strongly with DXA-derived %BF (r=0.83–0.89, p<0.01) in both boys and girls. However, forearm and lower leg %Fat CSA were higher than whole body %BF by 5% and 10%, respectively. A better prediction of whole-body %BF was achieved by including %Fat CSA, muscle density and height into a hierarchical regression model. Using sex-specific regression equations, 87.7% of the boys and 83.7% of the girls had a predicted %BF within 3% units of the %BF obtained by DXA.

Conclusion: In pre-pubertal children, pQCT measures of adiposity are strongly associated with whole-body per cent body fat. This reproducible method could be an alternative technique to estimate body composition in this population.

Touching space : using motion capture and stereo projection to create a virtual haptics of dance

This paper describes the work of a group of artists in Australia who used real-time motion capture and 3D stereo projection to create a large-scale performance environment in which dancers seemed to "touch" the volume. This project re-versions Suzanne Langer's 1950s philosophy of dance as "virtual force" to realize the idea of a "virtual haptics" of dance that extends the dancer's physical agency literally across and through the surrounding spatial volume. The project presents a vision of interactive dance performance that "touches" space by visualizing kinematics as intentionality and agency. In doing so, we suggest the possibility of new kinds of human-computer interfaces that emphasize touch as embodied, nuanced agency that is mediated by the subtle qualities of whole-body movement, in addition to more goal-oriented, task-based gestures such as pointing or clicking.

Bone mineral density reference ranges for Australian men : Geelong Osteoporosis Study

Summary : A large population-based random sample of Australian white men was used to provide normative bone mineral density (BMD) data at multiple anatomical sites. The femoral neck BMD data are very similar to those obtained in USA non-Hispanic white males participating in the National Health and Nutrition Examination Survey III (NHANES III). The reference ranges will be suitable for similar populations.

Introduction : To provide normative BMD data for Australian men derived from a large population-based random sample.

Methods : An age-stratified random sample of men was recruited from the Australian electoral rolls (n = 1,467 aged 20–97 years). BMD was quantified at multiple sites using Lunar densitometers.

Results : Age-related differences in BMD were best predicted by linear relationships at the spine and hip and by quadratic functions at the whole body and forearm. At the spine, a small age-related increase in mean BMD was observed. Although in the subset with no spinal abnormalities, there was a decrease of 0.003 g/cm² per year from age 20. At the hip sites, mean BMD decreased at 0.001–0.006 g/cm² per year from age 20. At the forearm and whole body, BMD peaked at 41–47 years. Apart from a small difference in men greater than or equal to 80 years, the Australian femoral neck BMD data are not different to those obtained in USA non-Hispanic white males participating in NHANES III and were generally similar to those of large studies from Canada (CaMos) and Spain.

Conclusions : These data supply BMD reference ranges at multiple anatomical sites that will be applicable to white Australian men and similar populations such as USA non-Hispanic white men.

Serum leptin levels are associated with bone mass in nonobese women

Both serum leptin and bone mineral density are positively correlated with body fat, generating the hypothesis that leptin may be a systemic and/or local regulator of bone mass. We investigated 214 healthy, nonobese Australian women aged 20-91 yr. Bone mineral content, projected bone area, and body fat mass were measured by dual energy x-ray absorptiometry and fasting serum leptin levels by RIA. Associations between bone mineral content (adjusted for age, body weight, body fat mass, and bone area) and the natural logarithm of serum leptin concentrations were analyzed by multiple regression techniques. There was a significant positive association at the lateral spine, two proximal femur sites (Ward's triangle and trochanter), and whole body (partial r² = 0.019 to 0.036; all P < 0.05). Similar trends were observed at the femoral neck and posterior-anterior-spine. With bone mineral density the dependent variable (adjusted for age, body weight, and body fat mass), the association with the natural logarithm of leptin remained significant at the lateral spine (partial r² = 0.030; P = 0.011), was of borderline significance at the proximal femur sites (partial r² = 0.012 to 0.017; P = 0.058 to 0.120), and was not significant at the other sites. Our results demonstrate an association between serum leptin levels and bone mass consistent with the hypothesis that circulating leptin may play a role in regulating bone mass.

Behavioural and physical characteristics associated with vitamin D status in women

For most people in Australia, the primary source of vitamin D is casual exposure to sunlight. Hypovitaminosis D has been reported for high-risk populations, but little has been documented for women of all ages living in the community. Using cross-sectional data, we aimed to describe physical and behavioural characteristics associated with serum 25-hydroxyvitamin D (25OHD) for such women and to determine the association of serum 25OHD with hypertension and bone health. Serum 25OHD, parathyroid hormone (PTH), blood pressure, bone mineral density (BMD) and anthropometry were measured in a random sample of 861 women aged 20–92 years enrolled in the Geelong Osteoporosis Study, set in a temperate region at latitude 38–39°S. Lifestyle factors (including diet, smoking, medication use, socio-economic status, residence, education, occupation, and physical activity) were documented by questionnaire. In season-adjusted models for women aged 20–54 years, physical activity and living with a partner were independently and positively associated with serum 25OHD; associations with weight and waist–hip ratio were negative. Among older women, physical activity, vitamin D intake and urban dwelling were positively associated with serum 25OHD; age, weight and smoking were negative. Compared with the lowest tertile, those in the highest serum 25OHD tertile were less likely to have elevated serum PTH (adjusted OR = 0.25, 95% CI 0.16–0.41) and high blood pressure (adjusted OR = 0.40, 95% CI 0.22–0.72), and more likely to have normal hip and spine BMD (adjusted OR = 1.65, 95% CI 1.08–2.52). In multivariable models adjusting for season, age, weight (and height), BMD was associated with serum 25OHD at the spine, hip and whole body; no associations were detected at the forearm and no other characteristics were identified as confounders. Factors associated with high vitamin D status generally reflected healthy body habitus and active lifestyles. In contrast, excessive weight and smoking were associated with poorer vitamin D status. Women with high vitamin D were less likely to have elevated PTH, hypertension or bone deficits than women with poor levels.

β-blockers reduce bone resorption marker in early postmenopausal women

Background: There is evidence to suggest that β-blockers used in the management of cardiovascular disease may also modulate bone metabolism and reduce bone fragility.

Aim: The study aimed to determine the association between β-blocker use, serum markers of bone turnover and bone loss in early postmenopausal women.

Subjects and methods: In this observational study, we evaluated β-blocker exposure in association with serum levels of C-telopeptide and bone-specific alkaline phosphatase, and rates of bone loss. β-blocker use, concomitant therapy and lifestyle were documented for 197 women (50–59 years), 175 of whom had changes in whole body bone mineral density monitored over a 2–year period.

Results: Twenty-four β-blocker users were identified at baseline. After controlling for concomitant use of hormone therapy, C-telopeptide levels were 6.7% lower among β-blocker users (p = 0.02). No association was detected between bone-specific alkaline phosphatase and β-blocker use. Analysis of 15 β-blocker users and 152 non-users identified 2 years post-baseline showed that levels of C-telopeptide but not bone-specific alkaline phosphatase were predictors of adjusted rates of bone loss (p = 0.008 and p>0.05, respectively). Adjusted rates of bone loss were −0.001 ± 0.026 g cm−2 over 2 years for the users and −0.004 ± 0.025 g cm−2 over 2 years for non-users, but this difference was not significant.

Conclusion: β-blockers might suppress bone resorption with relative preservation of bone formation. A study with greater power is required to determine whether β-blocker use is associated with lower rates of bone loss.

Antioxidant vitamin supplements and markers of bone turnover in a community sample of nonsmoking women

Background: Whereas several epidemiological studies suggest that low dietary intake of vitamins C and E is linked to increased hip fracture in smokers and antioxidants (dietary and endogenous) are reduced in elderly osteoporotic women, none has demonstrated an effect of supplemental antioxidants on bone turnover.

Methods: In an observational study of 533 randomly selected women, we investigated the associations among the use of antioxidant supplements, vitamins C and E, serum levels of biochemical markers of bone turnover (C-telopeptide [CTx] and bone-specific alkaline phosphatase [BSAP]), and whole body bone mineral density (BMD).

Results: Twenty-two women were identified as current users of supplemental vitamin C or E. Duration of antioxidant supplement use was negatively associated with age-adjusted and weight-adjusted serum CTx, such that mean CTx levels (natural log transformed) were 0.022 units lower for each year of exposure. No significant differences were detected for adjusted serum BSAP or whole body BMD.

Conclusions: Our results suggest that antioxidant vitamin E or C supplements may suppress bone resorption in nonsmoking postmenopausal women. Coupling of bone formation and resorption may explain the absence of an effect on bone formation markers, given evidence of enhanced effects of antioxidants on osteoblast differentiation; this warrants further investigation. This work adds to the growing body of evidence that antioxidants may play a role in preventing osteoporosis.

Statin use, bone mineral density, and fracture risk: Geelong Osteoporosis Study

Background Recent data suggest that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) decrease fracture risk and increase bone mineral density (BMD).

Methods This cross-sectional study is set in southeastern Australia. We evaluated the association between statin use, fracture risk, and BMD in 1375 women (573 with incident fractures and 802 without incident fracture, all drawn from the same community). Fractures were identified radiologically. Medication use and lifestyle factors were documented by questionnaire.

Results Unadjusted odds ratio for fracture associated with statin use was 0.40 (95% confidence interval [CI], 0.23-0.71). Adjusting for BMD at the femoral neck, spine, and whole body increased the odds ratio to 0.45 (95% CI, 0.25-0.80), 0.42 (95% CI, 0.24-0.75), and 0.43 (95% CI, 0.24-0.78), respectively. Adjusting for age, weight, concurrent medications, and lifestyle factors had no substantial effect on the odds ratio for fracture. Statin use was associated with a 3% greater adjusted BMD at the femoral neck (P = .08), and BMD tended to be greater at the spine and whole body but did not achieve statistical significance.

Conclusion The substantial 60% reduction in fracture risk associated with statin use is greater than would be expected from increases in BMD alone.

Geelong Osteoporosis Study Health Database

The database contains the following clinical, questionnaire and socio-demographic data suitable for cross-sectional and longitudinal analyses:
-Body composition: dual-energy x-ray absorptiometry (DXA) measures of the lumbar spine (posterior-anterior projection), proximal femur, whole body and forearm (ultradistal forearm and distal 33%)
-Other clinical assessments: body weight, height, arm span, waist and hip circumferences, blood pressure, visual acuity, muscle strength, functional reach test and timed ‘up-&-go’ test.
-Mental health: Major axis psychiatric disorders diagnosed using a Structured Clinical Interview.
-Blood and urine collections: blood and urine collected after an overnight fast.
-Questionnaires: exposure to disease, use of medications and supplements, diet, mobility, physical activity, sleep, sun exposure, falls and fractures, alcohol and tobacco use, reproductive history, family history of fractures and disease, quality of life, pain, anxiety and depression.
-Socio-demographics: Country of birth, ethnicity, marital status, education, housing and employment status, occupation, socioeconomic Index for Areas (SEIFA) scores.

Fish oil replacement in rainbow trout diets and total dietary PUFA content : II) Effects on fatty acid metabolism and in vivo fatty acid bioconversion

This study aimed to gain a better understanding of the metabolic fate of dietary fatty acids in rainbow trout, with a specific focus on the effect of varying total C18 PUFA level. Fish were fed a control fish oil based diet or one of five experimental fish oil deprived diets formulated with a constant 1/1 ratio of 18:3n-3/18:2n-6 and varying total C18 PUFA levels for a period of 7 weeks. The transcriptional changes of the Δ-6 desaturase and elongase enzymes in direct comparison to in vivo fatty acid bioconversion, estimated using the whole-body fatty acid balance method, were analysed. The main findings were that i) the efficiency of Δ-6 desaturase was negatively affected by C18 PUFA availability, but the total apparent in vivo enzyme activity was directly proportional to C18 PUFA substrate availability; ii) Δ-6 desaturase had a greater affinity towards n-3PUFA than n-6PUFA; iii) excessive C18 PUFA substrate availability could limit the availability of Δ-6 desaturase to act on C24 fatty acid; iv) the elimination of dietary n-3LC-PUFA (enzyme products) up-regulated the transcription rate of Δ-6 desaturase; but v) the total apparent in vivo enzyme activity was directly and positively affected by substrate availability, and not product presence/absence nor the extent of the enzyme transcription rate.

Respiratory pattern in awake rats : effects of motor activity and of alerting stimuli

Our aim was to assess the impact of motor activity and of arousing stimuli on respiratory rate in the awake rats. The study was performed in male adult Sprague–Dawley (SD, n = 5) and Hooded Wistar (HW, n = 5) rats instrumented for ECG telemetry. Respiratory rate was recorded using whole-body plethysmograph, with a piezoelectric sensor attached for the simultaneous assessment of motor activity. All motor activity was found to be associated with an immediate increase in respiratory rate that remained elevated for the whole duration of movement; this was reflected by: i) bimodal distribution of respiratory intervals (modes for slow peak: 336 ± 19 and 532 ± 80 ms for HW and SD, p < 0.05; modes for fast peak 128 ± 6 and 132 ± 7 ms for HW and SD, NS); and ii) a tight correlation between total movement time and total time of tachypnoea, with an R2 ranging 0.96–0.99 (n = 10, p < 0001). The extent of motor-related tachypnoea was significantly correlated with the intensity of associated movement. Mild alerting stimuli produced stereotyped tachypnoeic responses, without affecting heart rate: tapping the chamber raised respiratory rate from 117 ± 7 to 430 ± 15 cpm; sudden side move — from 134 ± 13 to 487 ± 16 cpm, and turning on lights — from 136 ± 12 to 507 ± 14 cpm (n = 10; p < 0.01 for all; no inter-strain differences). We conclude that: i) sniffing is an integral part of the generalized arousal response and does not depend on the modality of sensory stimuli; ii) tachypnoea is a sensitive index of arousal; and iii) respiratory rate is tightly correlated with motor activity.

Effect of heat stress on glucose kinetics during exercise

To identify the mechanism underlying the exaggerated hyperglycemia during exercise in the heat, six trained men were studied during 40 min of cycling exercise at a workload requiring 65% peak pulmonary oxygen uptake (V˙o 2 peak) on two occasions at least 1 wk apart. On one occasion, the ambient temperature was 20°C [control (Con)], whereas on the other, it was 40°C [high temperature (HT)]. Rates of glucose appearance and disappearance were measured by using a primed continuous infusion of [6,6-2H]glucose. No differences in oxygen uptake during exercise were observed between trials. After 40 min of exercise, heart rate, rectal temperature, respiratory exchange ratio, and plasma lactate were all higher in HT compared with Con (P < 0.05). Plasma glucose levels were similar at rest (Con, 4.54 ± 0.19 mmol/l; HT, 4.81 ± 0.19 mmol/l) but increased to a greater extent during exercise in HT (6.96 ± 0.16) compared with Con (5.45 ± 0.18;P < 0.05). This was the result of a higher glucose rate of appearance in HT during the last 30 min of exercise. In contrast, the glucose rate of disappearance and metabolic clearance rate were not different at any time point during exercise. Plasma catecholamines were higher after 10 and 40 min of exercise in HT compared with Con (P < 0.05), whereas plasma glucagon, cortisol, and growth hormone were higher in HT after 40 min. These results indicate that the hyperglycemia observed during exercise in the heat is caused by an increase in liver glucose output without any change in whole body glucose utilization.

Effects of Dietary Vitamin B6 Supplementation on Fillet Fatty Acid Composition and Fatty Acid Metabolism of Rainbow Trout Fed Vegetable Oil Based Diets

Fish oil replacement in aquaculture feeds results in major modifications to the fatty acid makeup of cultured fish. Therefore, in vivo fatty acid biosynthesis has been a topic of considerable research interest. Evidence suggests that pyridoxine (vitamin B₆) plays a role in fatty acid metabolism, and in particular, the biosynthesis of LC-PUFA has been demonstrated in mammals. However, there is little information on the effects of dietary pyridoxine availability in fish fed diets lacking LC-PUFA. This study demonstrates a relationship between dietary pyridoxine supplementation and fatty acid metabolism in rainbow trout. In particular, the dietary pyridoxine level was shown to modulate and positively stimulate the activity of the fatty acid elongase and Δ-6 and Δ-5 desaturase enzymes, deduced by the whole-body fatty acid balance method. This activity was insufficient to compensate for a diet lacking in LC-PUFA but does highlight potential strategies to maximize this activity in cultured fish, especially when fish oil is replaced with vegetable oils.