Ken Sharpe

Low testosterone levels are common and associated with insulin resistance in men with diabetes.

CONTEXT Low testosterone levels are common in men with type 2 diabetes and may be associated with insulin resistance. OBJECTIVE We investigated prevalence of testosterone deficiency and the relationship between testosterone and insulin resistance in a large cohort of men with type 2 and type 1 diabetes. DESIGN The study was a cross-sectional survey of 580 men with type 2 diabetes and 69 men with type 1 diabetes. A subgroup of 262 men with type 2 diabetes was then reassessed after a median of 6 months. RESULTS Forty-three percent of men with type 2 diabetes had a reduced total testosterone, and 57% had a reduced calculated free testosterone. Only 7% of men with type 1 diabetes had low total testosterone. By contrast, 20.3% of men with type 1 diabetes had low calculated free testosterone, similar to that observed in type 2 diabetes (age-body mass index adjusted odds ratio = 1.4; 95% confidence interval = 0.7-2.9). Low testosterone levels were independently associated with insulin resistance in men with type 1 diabetes as well as type 2 diabetes. Serial measurements also revealed an inverse relationship between changes in testosterone levels and insulin resistance. CONCLUSIONS Testosterone deficiency is common in men with diabetes, regardless of the type. Testosterone levels are partly influenced by insulin resistance, which may represent an important avenue for intervention, whereas the utility of testosterone replacement remains to be established in prospective trials.

Exponential random graph (p*) models for affiliation networks

Abstract Recent advances in Exponential Random Graph Models (ERGMs), or p ∗ models, include new specifications that give a much better chance of model convergence for large networks compared with the traditional Markov models. Simulation based MCMC maximum likelihood estimation techniques have been developed to replace the pseudolikelihood method. To date most work on ERGMs has focused on one-mode networks, with little done in the case of affiliation networks with two or more types of nodes. This paper proposes ERGMs for two-mode affiliation networks drawing on the recent advances for one-mode networks, including new two-mode specifications. We investigate features of the models by simulation, and compared the goodness of fit results obtained using the maximum likelihood and pseudolikelihood approaches. We introduce a new approach to goodness of fit for network models, using a heuristic based on Mahalanobis distance. The classic Southern Women data and Australian Interlocking Director data are used as examples to show that the ERGM with the newly specified statistics is a powerful tool for statistical analysis of affiliation networks.

A randomised trial of domiciliary, ambulatory oxygen in patients with COPD and dyspnoea but without resting hypoxaemia

Background Patients with chronic obstructive pulmonary disease (COPD) who are not severely hypoxaemic at rest may experience significant breathlessness on exertion, and ambulatory oxygen is often prescribed in this circumstance despite a lack of conclusive evidence for benefit. This study aimed to determine whether such patients benefit from domiciliary ambulatory oxygen and, if so, which factors may be associated with benefit. Methods This was a 12 week, parallel, double-blinded, randomised, placebo-controlled trial of cylinder air versus cylinder oxygen, provided at 6 l/min intranasally, for use during any activity provoking breathlessness. Patients underwent baseline measurements of arterial blood gases and lung function. Outcome measures assessed dyspnoea, health-related quality of life, mood disturbance, functional status and cylinder utilisation. Data were analysed on an intention-to-treat basis, p≤0.05. Results 143 subjects (44 female), mean±SD age 71.8±9.8 years, forced expiratory volume in 1 s (FEV1)1.16±0.51 lites, Pao2 9.5±1.1 kPa (71.4±8.5 mm Hg) were randomised, including 50 patients with exertional desaturation to ≤88%. No significant differences in any outcome were found between groups receiving air or oxygen. Statistically significant but clinically small improvements in dyspnoea and depression were observed in the whole study group over the 12 weeks of the study. Conclusion In breathless patients with COPD who do not have severe resting hypoxaemia, domiciliary ambulatory oxygen confers no benefits in terms of dyspnoea, quality of life or function. Exertional desaturation is not predictive of outcome. Intranasal gas (either air or oxygen) may provide a placebo benefit. Clinical trial number ACTRN12605000457640.

Altitude training and haemoglobin mass from the optimised carbon monoxide rebreathing method determined by a meta-analysis

Objective To characterise the time course of changes in haemoglobin mass (Hbmass) in response to altitude exposure. Methods This meta-analysis uses raw data from 17 studies that used carbon monoxide rebreathing to determine Hbmass prealtitude, during altitude and postaltitude. Seven studies were classic altitude training, eight were live high train low (LHTL) and two mixed classic and LHTL. Separate linear-mixed models were fitted to the data from the 17 studies and the resultant estimates of the effects of altitude used in a random effects meta-analysis to obtain an overall estimate of the effect of altitude, with separate analyses during altitude and postaltitude. In addition, within-subject differences from the prealtitude phase for altitude participant and all the data on control participants were used to estimate the analytical SD. The ‘true’ between-subject response to altitude was estimated from the within-subject differences on altitude participants, between the prealtitude and during-altitude phases, together with the estimated analytical SD. Results During-altitude Hbmass was estimated to increase by ∼1.1%/100 h for LHTL and classic altitude. Postaltitude Hbmass was estimated to be 3.3% higher than prealtitude values for up to 20 days. The within-subject SD was constant at ∼2% for up to 7 days between observations, indicative of analytical error. A 95% prediction interval for the ‘true’ response of an athlete exposed to 300 h of altitude was estimated to be 1.1–6%. Conclusions Camps as short as 2 weeks of classic and LHTL altitude will quite likely increase Hbmass and most athletes can expect benefit.

Physique traits of lightweight rowers and their relationship to competitive success

Objectives: Physique traits and their relationship to competitive success were assessed amongst lightweight rowers competing at the 2003 Australian Rowing Championships. Methods: Full anthropometric profiles were collected from 107 lightweight rowers (n = 65 males, n = 45 females) competing in the Under 23 and Open age categories. Performance assessments were obtained for 66 of these rowers based on results in the single sculls events. The relationship between physique traits and competitive success was then determined. Results: Lower body fat (heat time estimate −8.4 s kg−1, p<0.01), greater total body mass (heat time estimate −4.4 s kg−1, p = 0.03), and muscle mass (heat time estimate −10.2 s kg−1, p<0.01) were associated with faster 2000 m heat times. Conclusions: The more successful lightweight rowers were those who had lower body fat and greater total muscle mass.

Detecting autologous blood transfusions: a comparison of three passport approaches and four blood markers.

Blood passport has been suggested as an indirect tool to detect various kinds of blood manipulations. Autologous blood transfusions are currently undetectable, and the objective of this study was to examine the sensitivities of different blood markers and blood passport approaches in order to determine the best approach to detect autologous blood transfusions. Twenty‐nine subjects were transfused with either one (n=8) or three (n=21) bags of autologous blood. Hemoglobin concentration ([Hb]), percentage of reticulocytes (%ret) and hemoglobin mass (Hbmass) were measured 1 day before reinfusion and six times after reinfusion. The sensitivity and specificity of a novel marker, Hbmr (based on Hbmass and %ret), was evaluated together with [Hb], Hbmass and OFF‐hr by different passport methods. Our novel Hbmr marker showed superior sensitivity in detecting the highest dosage of transfused blood, with OFF‐hr showing equal or superior sensitivities at lower dosages. Hbmr and OFF‐hr showed superior but equal sensitivities from 1 to 4 weeks after transfusion compared with [Hb] and Hbmass, with Hbmass being the only tenable prospect to detect acute transfusions. Because autologous blood transfusions can be an acute practice with blood withdrawal and reinfusion within a few days, Hbmass seems to be the only option for revealing this practice.

Effect of VDUs on the eyes: report of a 6-year epidemiological study.

One thousand, three hundred and sixteen office workers [692 visual display unit (VDU) users, 624 controls in the first year] were examined once each year over a 6-year period to establish whether or not VDU work was a factor in the occurrence of visual symptoms, ocular abnormalities, or ocular disease. Statistical analysis showed that although there were differences between VDU users and nonusers in the amount of myopia, the prevalence of some symptoms, and the prevalence of signs of fundal or vitreal disease, the differences were small and there were no clear trends or patterns to lend convincing support to the hypothesis that VDU work may be a risk factor. There were no significant differences in the prevalence and incidence of cataract.

Caffeine restriction: effect on mild hypertension.

OBJECTIVE--To determine the effects on blood pressure of modifying dietary caffeine intake in patients with mild and borderline hypertension by monitoring ambulatory and clinic blood pressure. DESIGN--Four way, randomised, crossover trial of four consecutive two week dietary regimens: normal diet, caffeine free diet alone, caffeine free diet with decaffeinated instant coffee, caffeine free diet with caffeinated instant coffee (instant coffee phases conducted double blind). SETTING--Hospital hypertension clinic, Scotland. PATIENTS--52 patients (23 men; aged 26-67 years) with untreated borderline or mild hypertension (diastolic blood pressure 90-105 mm Hg) who normally drank a minimum of three cups of coffee daily. MAIN OUTCOME MEASURES--Mean ambulatory blood pressure over 24 hours; mean morning, daytime, and night time ambulatory blood pressure; sitting clinic blood pressure at 1700; plasma caffeine concentration at 1700 on the last day of each regimen. RESULTS--Mean 24 hour ambulatory blood pressure was not different between regimens. There was no difference in blood pressure variability between regimens. During the caffeine free diet alone morning ambulatory diastolic blood pressure was higher (2.8 mm Hg) than during the caffeine free diet with caffeinated coffee. Mean sitting clinic systolic blood pressure was higher at 1700 (4.7 mm Hg) with a caffeine free diet than with the caffeine free diet with caffeinated coffee (p less than 0.05). Dietary compliance as assessed by plasma caffeine concentration was excellent. There was no significant correlation between plasma caffeine concentration and blood pressure. CONCLUSIONS--Drinking caffeinated instant coffee over a two week period does not adversely influence blood pressure in patients with borderline or mild hypertension; abstinence is of no benefit.

Low testosterone and anaemia in men with type 2 diabetes

Objective  Anaemia is frequently found in patients with diabetes, in whom it is associated with increased morbidity and mortality. Low testosterone levels are also common in men with type 2 diabetes. We hypothesized that low testosterone levels are also associated with anaemia in men with type 2 diabetes, over the effects of chronic kidney disease.

Pilot Study of Remote Telemonitoring in COPD

BACKGROUND Remote in-home monitoring (RM) of symptoms and physiological variables may allow early detection and treatment of exacerbations of chronic obstructive pulmonary disease (COPD). It is unclear whether RM improves patient outcomes or healthcare resource utilization. This study determined whether RM is feasible in patients with COPD and if RM reduces hospital admissions or length of stay (LOS) or improves health-related quality of life (HRQOL). SUBJECTS AND METHODS Forty-four patients were randomized to standard best practice care (SBP) (n=22) or SBP+RM (n=22). RM involved daily recording of physiological variables, symptoms, and medication usage. RESULTS There were no differences (mean±SD, SBP versus SBP+RM) in age (68±8 versus 70±9 years), gender (male:female 10:12 in both groups), or previous computer familiarity (59% versus 50%) between groups. The SBP group had a lower forced expiratory volume in 1 s (0.66±0.24 versus 0.91±0.34 L, p<0.01) and more current smokers (six versus none, p<0.05). There were no differences in number of COPD-related admissions/year (1.5±1.8 versus 1.3±1.7, p=0.76), COPD-related LOS days/year (15.6±19.4 versus 11.4±19.6, p=0.66), total admissions/year (2.2±2.1 versus 2.0±2.3, p=0.86), total LOS days/year (22.1±29.9 versus 21.6±30.4, p=0.88), or HRQOL between the two groups. CONCLUSIONS The addition of RM to SBP was feasible but did not reduce healthcare utilization or improve quality of life in this group of patients already receiving comprehensive respiratory care.