Spatio-temporal selectivity of loss of colour and luminance contrast sensitivity with mutiple sclerosis and optic neuritis

Colour and luminance-contrast thresholds were measured in the presence of dynamic Random Luminance-contrast Masking (RLM) in individuals who had had past diagnoses of optic neuritis (ON) some of whom have progressed to a diagnosis of multiple sclerosis (MS). To explore the spatio-temporal selectivity of chromatic and luminance losses in MS/ON, thresholds were measured using three different sizes and modulation rates of the RLM displays: small checks modulating slowly, medium-sized checks with moderate modulation and large checks modulating rapidly. The colour of the chromatic stimuli used were specified in a cone-excitation space to measure relative impairments in red–green and blue–yellow chromatic channels. These observers showed chromatic thresholds along the L/(L + M) axis that were higher than those along the S-cone axis for all display sizes/modulation rates and both red-green and blue-yellow colour thresholds were higher than luminance-contrast thresholds. The principal change in thresholds with spatio-temporal changes in the display was a reduction in thresholds for L/(L + M) and S-cones with increasing check size and modulation rate. However, luminance contrast thresholds did not change with display size/rate. These results are consistent with MS/ON selectively affecting processing in colour pathways rather than in the magnocellular pathway, and that within the colour pathways neurones with opposed L- and M-cone inputs are more damaged than colour-opponent neurons with input from S-cones.

Does high-intensity resistance training maintain bone mass during moderate weight loss in older overweight adults with type 2 diabetes?

The aim was to investigate whether the addition of supervised high intensity progressive resistance training to a moderate weight loss program (RT+WLoss) could maintain bone mineral density (BMD) and lean mass compared to moderate weight loss (WLoss) alone in older overweight adults with type 2 diabetes. We also investigated whether any benefits derived from a supervised RT program could be sustained through an additional home-based program. This was a 12-month trial in which 36 sedentary, overweight adults aged 60 to 80 years with type 2 diabetes were randomized to either a supervised gymnasium-based RT+WLoss or WLoss program for 6 months (phase 1). Thereafter, all participants completed an additional 6-month home-based training without further dietary modification (phase 2). Total body and regional BMD and bone mineral content (BMC), fat mass (FM) and lean mass (LM) were assessed by DXA every 6 months. Diet, muscle strength (1-RM) and serum total testosterone, estradiol, SHBG, insulin and IGF-1 were measured every 3 months. No between group differences were detected for changes in any of the hormonal parameters at any measurement point. In phase 1, after 6 months of gymnasium-based training, weight and FM decreased similarly in both groups (P<0.01), but LM tended to increase in the RT+WLoss (n=16) relative to the WLoss (n=13) group [net difference (95% CI), 1.8% (0.2, 3.5), P<0.05]. Total body BMD and BMC remained unchanged in the RT+WLoss group, but decreased by 0.9 and 1.5%, respectively, in the WLoss group (interaction, P<0.05). Similar, though non-significant, changes were detected at the femoral neck and lumbar spine (L2-L4). In phase 2, after a further 6 months of home-based training, weight and FM increased significantly in both the RT+WLoss (n=14) and WLoss (n=12) group, but there were no significant changes in LM or total body or regional BMD or BMC in either group from 6 to 12 months. These results indicate that in older, overweight adults with type 2 diabetes, dietary modification should be combined with progressive resistance training to optimize the effects on body composition without having a negative effect on bone health.

Calcium- and vitamin D3 - fortified milk reduces bone loss at clinically relevant skeletal sites on llder men: a 2-year randomised controlled trial

In this 2-year randomized controlled study of 167 men >50 years of age, supplementation with calcium-vitamin D3-fortified milk providing an additional 1000 mg of calcium and 800 IU of vitamin D3 per day was effective for suppressing PTH and stopping or slowing bone loss at several clinically important skeletal sites at risk for fracture.

Introduction: Low dietary calcium and inadequate vitamin D stores have long been implicated in age-related bone loss and osteoporosis. The aim of this study was to assess the effects of calcium and vitamin D3 fortified milk on BMD in community living men >50 years of age.

Materials and Methods: This was a 2-year randomized controlled study in which 167 men (mean age ± SD, 61.9 ± 7.7 years) were assigned to receive either 400 ml/day of reduced fat (1%) ultra-high temperature (UHT) milk containing 1000 mg of calcium plus 800 IU of vitamin D3 or to a control group receiving no additional milk. Primary endpoints were changes in BMD, serum 25(OH)D, and PTH.

Results: One hundred forty-nine men completed the study. Baseline characteristics between the groups were not different; mean dietary calcium and serum 25(OH)D levels were 941 ± 387 mg/day and 77 ± 23 nM, respectively. After 2 years, the mean percent change in BMD was 0.9-1.6% less in the milk supplementation compared with control group at the femoral neck, total hip, and ultradistal radius (range, p < 0.08 to p < 0.001 after adjusting for covariates). There was a greater increase in lumbar spine BMD in the milk supplementation group after 12 and 18 months (0.8-1.0%, p ≤ 0.05), but the between-group difference was not significant after 2 years (0.7%; 95% CI, −0.3, 1.7). Serum 25(OH)D increased and PTH decreased in the milk supplementation relative to control group after the first year (31% and −18%, respectively; both p < 0.001), and these differences remained after 2 years. Body weight remained unchanged in both groups at the completion of the study.

Conclusions: Supplementing the diet of men >50 years of age with reduced-fat calcium- and vitamin D3-enriched milk may represent a simple, nutritionally sound and cost-effective strategy to reduce age-related bone loss at several skeletal sites at risk for fracture in the elderly.

Negative affect as a mediator between body dissatisfaction and extreme weight loss and muscle gain behaviors

Negative affect has been found to mediate the relationship between body dissatisfaction and bulimia. However, it is unknown if this relationship also applies to disordered eating, excessive exercise and strategies to increase muscle for men or women. The aim of this study was to investigate whether negative and positive affect mediate the relationship between body dissatisfaction, and these body change strategies. Respondents were 93 men and 97 women (age range: 18-25 years), who completed measures of body dissatisfaction, positive and negative affect and body change strategies to lose weight or increase muscles. Body dissatisfaction was associated with strategies to lose weight, dietary restraint and bulimia for both genders. Negative affect mediated the relationship between dissatisfaction with muscles and strategies to lose weight, dietary restraint and bulimia for women only. The results confirm previous findings related to the association between negative affect and disordered eating for women. They also demonstrate the need to further investigate the impact of negative affect on body change strategies, particularly among men, and those strategies related to increasing muscles.

On the effect of path loss rates on the optimal receiver position in sensor networks

In this paper we examine the problem of finding an optimal position for a receiver node in a single-hop sensor network. The basic idea is to minimize the network energy consumption according to a particular network cost function. Our contribution is to simply show the effect of signal path loss rates and sensor weighting on the optimal receiver position.

Agricultural intensification and loss of matrix habitat over 23 years in the West Wimmera, south-eastern Australia

The global trend toward more intensive forms of agriculture is changing the nature of matrix habitat in agricultural areas. Removal of components of matrix habitat can affect native biota at the paddock and the landscape scale, particularly where intensification occurs over large areas. We identify the loss of paddock trees due to the proliferation of centre pivot irrigation in dryland farming areas as a potentially serious threat to the remnant biota of these areas. We used a region of south-eastern Australia as a case study to quantify land use change from grazing and dryland cropping to centre pivot irrigation over a 23-year period. We also estimated rates of paddock tree loss in 5 representative landscapes within the region over the same period. The total area affected by centre pivots increased from 0 ha in 1980 to nearly 9000 ha by 2005. Pivots were more likely to be established in areas which had originally been plains savannah and woodlands containing buloke (Allocasuarina luehmannii), a food source for an endangered bird. On average, 42% of paddock buloke trees present in 1982 were lost by 2005. In the two landscapes containing several centre pivots, the loss was 54% and 70%. This accelerated loss of important components of matrix habitat is likely to result in species declines and local extinctions. We recommend that measures to alleviate the likely negative impacts of matrix habitat loss on native biota be considered as part of regional planning strategies.

Effect of a weight-loss program on mental stress-induced cardiovascular responses and recovery

Objective: We assessed the effect of weight loss on blood pressure (BP) and pulse rate during rest, psychological stress, and recovery after stress.

Methods: Two groups of men completed two mental stress tests 12 wk apart. The control group continued their usual diet, whereas the weight-loss group underwent a dietary weight-loss program in which they were randomized to a high-fruit/vegetable and low-fat dairy diet or a low-fat diet.

Results: Fifty-five men with a baseline BP of 125.9 ± 6.9/83.6 ± 7.1 mmHg (mean ± SD) completed the study (weight-loss group, n = 28; control group, n = 27). The weight-loss group lost weight (mean ± SEM, −4.3 ± 0.3 versus +0.4 ± 0.4 kg, P = 0.001) compared with controls and had a significant decrease in resting systolic BP (SBP; −2.0 ± 1.1% versus +2.0 ± 1.1%, P < 0.05). There was a greater decrease in SBP (P < 0.05) and pulse rate (P < 0.05) at all time points during the stress test in the weight loss compared with the control group. At week 12, SBP in 23 (82%) subjects in the weight-loss group and 24 (89%) in the control group returned to resting levels, with recovering levels in the weight-loss group returning to resting levels 6.1 ± 2.6 min earlier than in the control group (P < 0.05). There was an overall greater decrease in diastolic BP (DBP; P < 0.05) and DBP during recovery up to 27 min after stress (P < 0.05) in the high-fruit/vegetable and low-fat dairy diet group (n = 14) compared with the low-fat diet group (n = 14).

Conclusion: A 5% loss of weight decreased BP during rest and returned SBP to resting levels faster, thus decreasing the period of increased BP as a result of mental stress, which is likely to lower the risk of cardiovascular disease in the long term.

Determination of synephrine in weight-loss products using high performance liquid chromatography with acidic potassium permanganate chemiluminescence detection

Adrenergic amines found in extracts of Citrus aurantium (bitter orange) evoke analytically useful chemiluminescence with acidic potassium permanganate in the presence of polyphosphates. From corrected chemiluminescence spectra, the wavelength of maximum intensity for these reactions was 680 ± 5 nm and, using flow injection analysis methodology, limits of detection for synephrine, octopamine, tyramine and hordenine were found to be between 1 × 10⁻⁹ and 1 × 10⁻⁸ M. We have applied this method of detection to the rapid determination of synephrine in dietary supplements using monolithic column chromatography.

Upregulation of peroxisome proliferator-activated receptor gamma coactivator gene (PGC1A) during weight loss is related to insulin sensitivity but not to energy expenditure

Aims/hypothesis We investigated whether skeletal muscle peroxisome proliferator-activated receptor gamma coactivator-1 (PGC1A; also known as PPARGC1A) and its target mitofusin-2 (MFN2), as well as carnitine palmitoyltransferase-1 (CPT1; also known as carnitine palmitoyltransferase 1A [liver] [CPT1A]) and uncoupling protein (UCP)3, are involved in the improvement of insulin resistance and/or in the modification of energy expenditure during surgically induced massive weight loss.
Materials and methods Seventeen morbidly obese women (mean BMI: 45.9 ± 4 kg/m2) were investigated before, and 3 and 12 months after, Roux-en-Y gastric bypass (RYGB). We evaluated insulin sensitivity by the euglycaemic–hyperinsulinaemic clamp, energy expenditure and substrate oxidation by indirect calorimetry, and muscle mRNA expression by PCR.
Results Post-operatively, PGC1A was enhanced at 3 (p = 0.02) and 12 months (p = 0.03) as was MFN2 (p = 0.008 and p = 0.03 at 3 and 12 months respectively), whereas UCP3 was reduced (p = 0.03) at 12 months. CPT1 did not change. The expression of PGC1A and MFN2 were strongly (p < 0.0001) related. Insulin sensitivity, which increased after surgery (p = 0.002 at 3, p = 0.003 at 12 months), was significantly related to PGC1A and MFN2, but only MFN2 showed an independent influence in a multiple regression analysis. Energy expenditure was reduced at 3 months post-operatively (p = 0.001 vs before RYGB), remaining unchanged thereafter until 12 months. CPT1 and UCP3 were not significantly related to the modifications of energy expenditure or of lipid oxidation rate.
Conclusions/interpretation Weight loss upregulates PGC1A, which in turn stimulates MFN2 expression. MFN2 expression significantly and independently contributes to the improvement of insulin sensitivity. UCP3 and CPT1 do not seem to influence energy expenditure after RYGB.

Use of calcium or calcuim in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis

Background:  Whether calcium supplementation can reduce osteoporotic fractures is uncertain. We did a meta-analysis to include all the randomised trials in which calcium, or calcium in combination with vitamin D, was used to prevent fracture and osteoporotic bone loss.

Methods:  We identified 29 randomised trials (n=63 897) using electronic databases, supplemented by a hand-search of reference lists, review articles, and conference abstracts. All randomised trials that recruited people aged 50 years or older were eligible. The main outcomes were fractures of all types and percentage change of bone-mineral density from baseline. Data were pooled by use of a random-effect model.

Findings:  In trials that reported fracture as an outcome (17 trials, n=52 625), treatment was associated with a 12% risk reduction in fractures of all types (risk ratio 0·88, 95% CI 0·83–0·95; p=0·0004). In trials that reported bone-mineral density as an outcome (23 trials, n=41 419), the treatment was associated with a reduced rate of bone loss of 0·54% (0·35–0·73; p<0·0001) at the hip and 1·19% (0·76–1·61%; p<0·0001) in the spine. The fracture risk reduction was significantly greater (24%) in trials in which the compliance rate was high (p<0·0001). The treatment effect was better with calcium doses of 1200 mg or more than with doses less than 1200 mg (0·80 vs 0·94; p=0·006), and with vitamin D doses of 800 IU or more than with doses less than 800 IU (0·84 vs 0·87; p=0·03).

Interpretation:  Evidence supports the use of calcium, or calcium in combination with vitamin D supplementation, in the preventive treatment of osteoporosis in people aged 50 years or older. For best therapeutic effect, we recommend minimum doses of 1200 mg of calcium, and 800 IU of vitamin D (for combined calcium plus vitamin D supplementation).

Dissecting obesogenic behaviours: the development and application of a test battery for targeting prescription for weight loss

There are limited practical tools to help clinicians or public health workers manage obesity in their patients. We have previously developed a scanning technique for diagnosing environments leading to obesity (Analysis Grid for Environments/Elements Leading to Obesity). Here we describe the development of a tool for identifying behaviours in an individual most likely to lead to obesity. A questionnaire battery of five tests called the DAB-Q (Diet, Activity and Behaviour Questionnaire) was developed, piloted and internally validated with overweight women from a commercial weight loss programme. Outcome from the tests, which are available free on the Internet, provides clinicians with a simple, effective and time-saving tool for ranking foods, drinks and activities likely to be most effectively targeted for weight loss in an individual. This is based on total scores derived from measures of frequency, potential for change and potency of each item as a potential contributor to overweight.

Framing the discourses of harm and loss: a case study of power relations, mobile phones, and children in Australia

The current penetration of mobile phones in Australia is 92% and it records one of the world’s highest rates of ownership among children under 18. The paper reviews the literature on mobile phones and Australian children and examines the various discourses dominating the public debates; the systematic frames used in these discourses; and whose interests are served in the process. The frames discussed fall under the optimistic (gains); pessimistic (losses, costs or harms); pluralistic (technology per se is neutral but how it is used matters); historical development (skills learnt and the importance of using mobiles); futuristic predictions (promises and dangers for the future); current uses (connectivity, convergence and interactivity); and the techno-realist view (as a mixed blessing) views of technology. Taking the critical perspective and borrowing from Joshua Meyrowitz, the paper illustrates how mobile phones have eroded parental power over how, when, where and with whom their children communicate, surpassing adult supervision, intervention or knowledge, while at the same time, becoming a ‘digital leash’ for parents to re-establish their control an d an ‘umbilical cord’ for their off spring to remain connect! ed with parents, at all times.

Benefits of a year-long workplace weight loss program on cardiovascular risk factors

Objective: To assess the effectiveness of a year-long workplace weight loss program in reducing risk factors of coronary heart disease.

Design: A randomised, controlled study of low fat (25% of dietary energy) diet- and/or moderate exercise-induced weight loss interventions in free-living, middle-aged men. Compliance was monitored from food and activity diaries at monthly blood pressure measurement sessions. Blood was sampled and body composition determined from dual energy X-ray absorptiometry before and after 12 months.

Subjects and setting: Fifty-eight overweight men (mean [+ or -] SD age: 43.4 [+ or -] 5.7 years; BMI 29.0 [+ or -] 2.6 kg/[m.sup.2]), recruited from a national corporation, were instructed into diet (n = 18) exercise (a 21) or control (n = 19) groups over 12 months; 16 control subjects combined diet and exercise (n = 16) for the subsequent 12 months.

Main outcome measures: At 12 months, weight, total and regional fat and lean mass, dietary energy and percentage dietary fat intake, physical activity indices, systolic and diastolic blood pressure, serum insulin, blood lipids and lipoproteins.

Statistical analyses: Differences between groups were tested using analysis of variance with Scheffe post hoc test. Differences between pre- and post-intervention variables were tested using Students' paired t-tests. Pearson's correlation coefficient and univariate linear regression identified association between dependent variables, multiple stepwise regression identified specific predictors.

Results: Weight loss with either diet or exercise resulted in a reduction in systolic blood pressure (-3.3 [+ or -] 1.7%), diastolic blood pressure (-4.8 [+ or -] 1.3%) and LDL cholesterol (-3.9 [+ or -] 2.8%), a rise in HDL cholesterol (+10.0 [+ or -] 3.8%) and a change in the LDL/HDL ratio (-8.9 [+ or -] 3.5%). Abdominal fat loss (-26.8 [+ or -] 3.6% after diet; -16.6 [+ or -] 4.5% after exercise; -21.0 [+ or -] 4.7% after diet and exercise) was the strongest predictor of change in blood pressure: twenty percent abdominal fat loss predicted a percentage fall of 2.4 [+ or -] 0.05% in systolic blood pressure and 5.4 [+ or -] 0.07% in diastolic blood pressure. Greater abdominal fat loss was associated with the greatest decrease in serum insulin (P < 0.05).

Conclusion: Modest changes in diet and exercise effected by a low cost workplace-based education program achieved weight loss, loss of abdominal fat, reduced blood pressure and serum insulin and improved blood lipid concentrations. (Nutr Diet 2002;59:87-96)

Sustained weight loss in obese subjects has benefits that are independent of attained weight

Objective: To explore the hypothesis that sustained weight loss in severely obese patients may have benefits that are independent of their attained BMI. Research Methods and Procedures: We conducted a comparison of two weight-stable groups with BMI in the 30 to 35 kg/m2 range. Subjects (n = 79) were selected obese patients 3 years after laparoscopic adjustable gastric band surgery, and controls (n = 79) were obese patients seeking weight loss therapy. Subjects were selected in a de-identified manner from our database to best match the control group. A range of clinical, biochemical, and questionnaire measures were obtained to assess obesity-related health status Results: Subjects maintained a mean weight loss of 32.8 plusminus 18 kg after surgery. The weight loss subjects had significantly lower fasting plasma glucose, insulin, and triglyceride concentrations, along with higher high-density lipoprotein-cholesterol levels and better indirect measures of insulin sensitivity when compared with controls (p < 0.05 for all). In addition, aminotransferase levels, neutrophil counts, and globulin levels were also significantly lower in weight loss subjects. All differences in laboratory variables remained significant after controlling for BMI. The subjects also reported better health-related quality of life, fewer symptoms of depression, and greater satisfaction with their appearance than controls. Discussion: These findings suggest that the post-weight loss state conveys benefits that are greater than predicted by the attained BMI. These findings may have important implications regarding the expectations of weight loss therapy, and mechanisms for this effect should be carefully sought.