Creatine supplementation prevents acute strength loss induced by concurrent exercise

Purpose

To investigate the effect of creatine (CR) supplementation on the acute interference induced by aerobic exercise on subsequent maximum dynamic strength (1RM) and strength endurance (SE, total number of repetitions) performance.

Methods

Thirty-two recreationally strength-trained men were submitted to a graded exercise test to determine maximal oxygen consumption (VO_2max: 41.56 ± 5.24 ml kg^?1 min^?1), anaerobic threshold velocity (AT_v: 8.3 ± 1.18 km h^?1), and baseline performance (control) on the 1RM and SE (4 × 80 % 1RM to failure) tests. After the control tests, participants were randomly assigned to either a CR (20 g day^?1 for 7 days followed by 5 g day^?1 throughout the study) or a placebo (PL-dextrose) group, and then completed 4 experimental sessions, consisting of a 5-km run on a treadmill either continuously (90 % AT_v) or intermittently (1:1 min at vVO_2max) followed by either a leg- or bench-press SE/1RM test.

Results

CR was able to maintain the leg-press SE performance after the intermittent aerobic exercise when compared with C (p > 0.05). On the other hand, the PL group showed a significant decrease in leg-press SE (p ≤ 0.05). CR supplementation significantly increased bench-press SE after both aerobic exercise modes, while the bench-press SE was not affected by either mode of aerobic exercise in the PL group. Although small increases in 1RM were observed after either continuous (bench press and leg press) or intermittent (bench press) aerobic exercise in the CR group, they were within the range of variability of the measurement. The PL group only maintained their 1RM.

Conclusions

In conclusion, the acute interference effect on strength performance observed in concurrent exercise may be counteracted by CR supplementation.     

Systems Medicine: from molecular features and models to the clinic in COPD

Background and hypothesis

Chronic Obstructive Pulmonary Disease (COPD) patients are characterized by heterogeneous clinical manifestations and patterns of disease progression. Two major factors that can be used to identify COPD subtypes are muscle dysfunction/wasting and co-morbidity patterns. We hypothesized that COPD heterogeneity is in part the result of complex interactions between several genes and pathways. We explored the possibility of using a Systems Medicine approach to identify such pathways, as well as to generate predictive computational models that may be used in clinic practice.

Objective and method

Our overarching goal is to generate clinically applicable predictive models that characterize COPD heterogeneity through a Systems Medicine approach. To this end we have developed a general framework, consisting of three steps/objectives: (1) feature identification, (2) model generation and statistical validation, and (3) application and validation of the predictive models in the clinical scenario. We used muscle dysfunction and co-morbidity as test cases for this framework.

Results

In the study of muscle wasting we identified relevant features (genes) by a network analysis and generated predictive models that integrate mechanistic and probabilistic models. This allowed us to characterize muscle wasting as a general de-regulation of pathway interactions. In the co-morbidity analysis we identified relevant features (genes/pathways) by the integration of gene-disease and disease-disease associations. We further present a detailed characterization of co-morbidities in COPD patients that was implemented into a predictive model. In both use cases we were able to achieve predictive modeling but we also identified several key challenges, the most pressing being the validation and implementation into actual clinical practice.

Conclusions

The results confirm the potential of the Systems Medicine approach to study complex diseases and generate clinically relevant predictive models. Our study also highlights important obstacles and bottlenecks for such approaches (e.g. data availability and normalization of frameworks among others) and suggests specific proposals to overcome them.

     

Serum Leptin and Skeletal Differences between Obese and Non-Obese Patients with Chronic Obstructive Pulmonary Disease

ObjectiveChronic obstructive pulmonary disease (COPD) affects body composition, adipokine secretion, and skeletal integrity. The aim was to determine the association between leptin, body mass (BM) and body composition parameters - fat mass (FM) and fat mass index (FMI), lean tissue mass (LTM), lean tissue mass index (LTMI) and bone mineral density (BMD) in 67 male COPD patients.MethodsBM, body composition and biochemical indicators were measured or calculated using standard methods. Data were analyzed according to groups: non-obese (N = 48, BMI 21.0-29.9 kg/m²) and obese (N = 19, BMI ≥ 30.0 kg/m²).ResultsIn the non-obese group statistically significant correlations were observed: negative ones of age with most BMD T scores, positive ones of BMI with all T scores, FM, FMI, LTMI and leptin, of FMI with leptin and all T scores, and of LTMI with most T scores. In the obese group also statistically significant correlations were found: positive ones of BMI with FMI, LTM, leptin and T scores (trochanter, total hip); of FMI with leptin; and of leptin with total hip T score.ConclusionA positive relationship between FMI and BMD was found only in non-obese but not in obese COPD patients. Leptin concentration was associated positively with the total hip T score only in obese COPD patients, suggesting its protective role on the skeleton of obese COPD patients.Key Words: Body mass, Body mass index, Fat mass, Fat mass index, Lean tissue mass, Lean tissue mass index, 25-OH vitamin D, Leptin, Bone mineral density     

Tobacco use and smoking cessation among third‐year dental students in southern Brazil

The aim of the present cross‐sectional study was to assess tobacco use and smoking cessation among third‐year dental students in southern Brazil. The Global Health Professions Student Survey questionnaire was used in eight dental schools in Rio Grande do Sul state, Brazil. Of the 663 eligible students, 576 (87%) participated. The prevalence of current smoking was 19.1% [95% confidence interval (CI): 12.9–25.3%], and 61.6% (95% CI: 54.9–68.3%) of students reported having smoked at least once in their lifetime. The prevalence of dental students who had smoked ≥100 cigarettes in their lifetime was 17.1% (95% CI: 12.5–21.7%). Being frequently exposed to other smokers at home or in other places (second‐hand smoke) increased the likelihood of current smoking by two‐ to threefold. Approximately 6.1% (95% CI: 3.5–8.7%) of the students reported that they currently wanted to stop smoking and 7.5% (95% CI: 5.3–9.6%) had tried to stop smoking in the last year. Friends and family were the most frequent sources of help or counselling, and only a limited proportion of students received help from health professionals. Tobacco use and exposure to second‐hand smoking is widespread among dental students in southern Brazil. Smoking‐cessation initiatives targeting health care students are urgently needed.     

Is There a Positive Effect of Smoking Cessation on Periodontal Health? A Systematic Review

Background: Although the detrimental effects of tobacco on the periodontal tissues have been reported extensively, little is known about the potential beneficial effect of smoking cessation on periodontal health. The aim of this systematic review is to evaluate the effect of smoking cessation on periodontitis progression and response to periodontal therapy. Methods: Two independent reviewers completed the review process through title (n = 118), abstract (n = 24), and whole‐paper selection (n = 5). Sources include Medline and EMBASE databases (up to December 2012) and a reference list of selected studies. Prospective studies comparing progression rates of periodontitis between smokers and quitters and clinical trials evaluating the effect of smoking‐cessation programs, alone or in combination with periodontal treatment, were included. At least 1 year of follow‐up was required for inclusion. Results: Of 331 potentially relevant publications, five studies fulfilled the inclusion criteria. Because of heterogeneity of the studies, a meta‐analysis could not be performed. One study reported that the progression of clinical attachment loss (AL) ≥3 mm during a 6‐year period was approximately three times higher among smokers than quitters (P <0.001). Two studies (10 and 20 years of follow‐up) observed a decrease in radiographic bone loss of ≈30% among quitters when compared with smokers. Among individuals receiving non‐surgical periodontal treatment, quitters were more likely to have periodontal probing depth reductions (P <0.05) than non‐quitters/oscillators. No differences in AL were observed. Conclusion: Based on the limited available evidence, smoking cessation seems to have a positive influence on periodontitis occurrence and periodontal healing.     

Colorectal cancer morbidity in Poland and Japan in the years 1999–2006 – a comparison

Introduction

The frequency of colorectal cancer (CRC) is dependent on sex and age. The illness more often affects men than women, and a considerable increase in morbidity is noted after 65 years of age. The aim of the study was to assess the influence of various risk factors on CRC morbidity, statistical data from countries varied in cultural, socioeconomic and biological terms need to be studied. Poland and Japan can serve as examples of such contrasts.

Material and methods

The basis for the analysis of CRC morbidity was statistical data from Poland and Japan gathered in the period 1999–2006. They were expressed in absolute numbers and were related to the total morbidity, as well as morbidity according to sex and age.

Results

In the years 1999–2006, the total morbidity in Japan was on average 2.3 times higher than in Poland. The value was 2.5 times higher among men and 2.1 times among women when compared to Poland. In both countries morbidity is closely related to age and it reaches a peak between 65 and 74 years of age. Although the change in morbidity over the period was the same for Poland and Japan, there are considerable differences concerning the sex of the patients.

Conclusions

There is a substantial increase in CRC morbidity in both countries, especially among elderly people, which may point to the predominant influence of environmental factors and population aging in both countries. The much higher increase in morbidity among Polish men when compared to Polish women, not observed in the Japanese population, requires further study.     

Enzymatic activity of type 1 iodothyronine deiodinase in selected liver tumors

Introduction

Type 1 iodothyronine deiodinase (D1) converts thyroxin (T4) into tri-iodothyronine (T3). Strong evidence indicates that thyroid hormone metabolism is disturbed in neoplasms such as thyroid and breast cancer. However, there is limited data concerning the function of the D1 enzyme in liver tumors. We aimed to estimate the enzymatic activity of D1 in two different common liver tumors.

Material and methods

We obtained 20 tumor samples from patients who had undergone a liver resection. Of the tissue samples, there were 13 benign lesions of focal nodular hyperplasia (FNH) and 7 malignant lesions of hepatocellular carcinomas (HCC). The D1 activity was assessed by measuring the amount of radioactive iodine released in reaction to D1-catalysed deiodination. Groups were compared by the Mann-Whitney non-parametrical test for independent trials, and the Kruskal Wallis test.

Results

The enzymatic activity of D1 was not significantly altered in the FNH group (median = 536 fmol/mg of protein/min; p = 0.972) and HCC group (367 fmol/mg; p = 0.128) when compared to matched normal liver parenchyma controls (546 fmol/mg and 556 fmol/mg, respectively).

Conclusions

Liver parenchyma expresses high levels of D1. The results clearly revealed that D1 activity was not significantly different between benign and malignant tumors (FNH and HCC) compared to healthy liver parenchyma cells.