Circulating microRNAs as potential biomarkers of aerobic exercise capacity

Purpose microRNAs (miRs) are crucial intracellular mediators of various biological processes, also affecting the cardiovascular system. Recently, it has been shown that miRs circulate extracellularly in the bloodstream and that such circulating miRs change in response to physical activity. Therefore, the purpose of the current study was to investigate heart/muscle specific and inflammation related miRs in plasma of individuals before, directly after, and 24 h after a marathon run and to analyze their relation to conventional biochemical, cardiovascular, and performance indexes. Male endurance athletes (n =14) were recruited for the study after performing a battery of cardiac functional tests. Blood samples were collected before, directly after, and 24 h after a public marathon run. miR-1, miR-133, miR-206, miR-499, miR-208b, miR-21, and miR-155 were measured using individual Taqman assays and normalized to Caenorhabditis elegans miR-39 (cel-39) spike-in control. Moreover, soluble cardiac, inflammatory, and muscle damage markers were determined. As a result, skeletal- and heart muscle-specific miRs showed a significant increase after the marathon. The strongest increase was observed for miR-206. Twenty-four hours after the run, only miR-499 and miR-208b were returned to preexercise levels, whereas the others were still enhanced. In contrast, miR-21 and -155 were not affected by exercise. miR-1, -133a, and -206 correlated to aerobic performance parameters such as maximum oxygen uptake (V̇o_2max) and running speed at individual anaerobic lactate threshold (V_IAS). miR-1 showed a moderate negative correlation with fractional shortening, whereas miR-133a was positively related to the thickness of intraventricular septum. None of the miRs correlated with cardiac injury markers such as troponin T, troponin I, and pro-brain natriuretic peptide. In conclusion, these findings suggest a potential role for muscle- and heart-specific miRs in cardiovascular adaptation processes after endurance exercise. Moreover, the specific correlation of miR-1, -133a, and -206 to performance parameters indicated their potential role as biomarkers of aerobic capacity.

Supplementing healthy rats with a high-niacin dose has no effect on muscle fiber distribution and muscle metabolic phenotype

PURPOSE

It was recently shown that niacin prevents the obesity-induced type I to type II fiber switching in skeletal muscle of obese rats and favors the development of a more oxidative metabolic phenotype and thereby increases whole body utilization of fatty acids. Whether niacin also causes type II to type I fiber switching in skeletal muscle of healthy rats has not been investigated yet. Thus, the present study aimed to investigate whether niacin supplementation influences fiber distribution and metabolic phenotype of different skeletal muscles with a distinct type I-to-type II fiber ratio in healthy rats.

METHODS

Twenty-four male, 10-week-old Sprague-Dawley rats were randomly assigned into two groups of 12 rats each and fed either a control diet with 30 mg supplemented niacin/kg diet (control group) or a high-niacin diet with 780 mg supplemented niacin/kg diet (high-niacin group).

RESULTS

After 27 days of treatment, the percentage number of type I fibers in rectus femoris, gastrocnemius, and tibialis anterior muscles was 5-10% greater in the niacin group than in the control group, but did not differ between groups in soleus and vastus intermedius muscles. Transcript levels of genes encoding transcription factors regulating fiber switching, fiber-specific myosin heavy chain isoforms, and proteins involved in fatty acid utilization, oxidative phosphorylation, and angiogenesis did not differ between groups.

CONCLUSIONS

The results show that niacin has only negligible effects on fiber distribution and its regulation as well as the metabolic phenotype of skeletal muscle in healthy rats.

Niacin supplementation induces type II to type I muscle fiber transition in skeletal muscle of sheep

Background

It was recently shown that niacin supplementation counteracts the obesity-induced muscle fiber transition from oxidative type I to glycolytic type II and increases the number of type I fibers in skeletal muscle of obese Zucker rats. These effects were likely mediated by the induction of key regulators of fiber transition, PPARδ (encoded by PPARD), PGC-1α (encoded by PPARGC1A) and PGC-1β (encoded by PPARGC1B), leading to type II to type I fiber transition and upregulation of genes involved in oxidative metabolism. The aim of the present study was to investigate whether niacin administration also influences fiber distribution and the metabolic phenotype of different muscles [M. longissimus dorsi (LD), M. semimembranosus (SM), M. semitendinosus (ST)] in sheep as a model for ruminants. For this purpose, 16 male, 11 wk old Rhoen sheep were randomly allocated to two groups of 8 sheep each administered either no (control group) or 1 g niacin per day (niacin group) for 4 wk.

Results

After 4 wk, the percentage number of type I fibers in LD, SM and ST muscles was greater in the niacin group, whereas the percentage number of type II fibers was less in niacin group than in the control group (P < 0.05). The mRNA levels of PPARGC1A, PPARGC1B, and PPARD and the relative mRNA levels of genes involved in mitochondrial fatty acid uptake (CPT1B, SLC25A20), tricarboxylic acid cycle (SDHA), mitochondrial respiratory chain (COX5A, COX6A1), and angiogenesis (VEGFA) in LD, SM and ST muscles were greater (P < 0.05) or tended to be greater (P < 0.15) in the niacin group than in the control group.

Conclusions

The study shows that niacin supplementation induces muscle fiber transition from type II to type I, and thereby an oxidative metabolic phenotype of skeletal muscle in sheep as a model for ruminants. The enhanced capacity of skeletal muscle to utilize fatty acids in ruminants might be particularly useful during metabolic states in which fatty acids are excessively mobilized from adipose tissue, such as during the early lactating period in high producing cows.

Functional and muscular adaptations in an experimental model for isometric strength training in mice

Exercise training induces muscular adaptations that are highly specific to the type of exercise. For a systematic study of the differentiated exercise adaptations on a molecular level mouse models have been used successfully. The aim of the current study was to develop a suitable mouse model of isometric strength exercise training characterized by specific adaptations known from strength training. C57BL/6 mice performed an isometric strength training (ST) for 10 weeks 5 days/week. Additionally, either a sedentary control group (CT) or a regular endurance training group (ET) groups were used as controls. Performance capacity was determined by maximum holding time (MHT) and treadmill spirometry, respectively. Furthermore, muscle fiber types and diameter, muscular concentration of phosphofructokinase 1 (PFK), succinate dehydrogenase (SDHa), and glucose transporter type 4 (GLUT4) were determined. In a further approach, the effect of ST on glucose intolerance was tested in diabetic mice. In mice of the ST group we observed an increase of MHT in isometric strength tests, a type II fiber hypertrophy, and an increased GLUT4 protein content in the membrane fraction. In contrast, in mice of the ET group an increase of VO_2max, a shift to oxidative muscle fiber type and an increase of oxidative enzyme content was measured. Furthermore strength training was effective in reducing glucose intolerance in mice fed a high fat diet. An effective murine strength training model was developed and evaluated, which revealed marked differences in adaptations known from endurance training. This approach seems also suitable to test for therapeutical effects of strength training.

Niacin supplementation increases the number of oxidative type I fibers in skeletal muscle of growing pigs

Background

A recent study showed that niacin supplementation counteracts the obesity-induced muscle fiber switching from oxidative type I to glycolytic type II and increases the number of type I fibers in skeletal muscle of obese Zucker rats. These effects were likely mediated by the induction of key regulators of fiber transition, PGC-1α and PGC-1β, leading to muscle fiber switching and up-regulation of genes involved in mitochondrial fatty acid import and oxidation, citrate cycle, oxidative phosphorylation, mitochondrial biogenesis. The aim of the present study was to investigate whether niacin supplementation causes type II to type I muscle and changes the metabolic phenotype of skeletal muscles in growing pigs.

Results

25 male, 11 wk old crossbred pigs (Danzucht x Pietrain) with an average body weight of 32.8 ± 1.3 (mean ± SD) kg were randomly allocated to two groups of 12 (control group) and 13 pigs (niacin group) which were fed either a control diet or a diet supplemented with 750 mg niacin/kg diet. After 3 wk, the percentage number of type I fibers in three different muscles (M. longissismus dorsi, M. quadriceps femoris, M. gastrocnemius) was greater in the niacin group and the percentage number of type II fibers was lower in the niacin group than in the control group (P < 0.05). The mRNA levels of PGC-1β and genes involved in mitochondrial fatty acid catabolism (CACT, FATP1, OCTN2), citrate cycle (SDHA), oxidative phosphorylation (COX4/1, COX6A1), and thermogenesis (UCP3) in M. longissimus dorsi were greater in the niacin group than in the control group (P < 0.05).

Conclusions

The study demonstrates that niacin supplementation induces type II to type I muscle fiber switching, and thereby an oxidative metabolic phenotype of skeletal muscle in pigs. Given that oxidative muscle types tend to develop dark, firm and dry pork in response to intense physical activity and/or high psychological stress levels preslaughter, a niacin-induced change in the muscle´s fiber type distribution may influence meat quality of pigs.

The new 2012 German recommendations for treating rheumatoid arthritis : differences compared to the European standpoint

The German Society for Rheumatology recently published guidelines for the sequential therapy of rheumatoid arthritis (RA). These recommendations were developed as a transition from the 2010 EULAR (EUropean League Against Rheumatism) recommendations to the national clinical practice and are based on an updated systematic literature research and expert discussion. While most EULAR recommendations have remained unchanged, some were modified based on new evidence from randomized, controlled trials, current clinical practice, or national drug approval status. The guidelines also include a treatment algorithm for sequential therapy of RA with disease-modifying agents including biologics.

Carnitine supplementation to obese Zucker rats prevents obesity-induced type II to type I muscle fiber transition and favors an oxidative phenotype of skeletal muscle

BACKGROUND

In the present study, we tested the hypothesis that carnitine supplementation counteracts obesity-induced muscle fiber transition from type I to type II.

METHODS

24 obese Zucker rats were randomly divided into two groups of 12 rats each (obese control, obese carnitine) and 12 lean Zucker rats were selected for lean control group. A control diet was given to both control groups and a carnitine supplemented diet (3 g/kg diet) was given to obese carnitine group for 4 wk. Components of the muscle fiber transformation in skeletal muscle were examined.

RESULTS

The plasma level of carnitine were lower in the obese control group compared to the lean control group and higher in the obese carnitine group than in the other groups (P < 0.05). Plasma concentrations of triglycerides and non-esterified fatty acids were increased in obese animals compared to lean animals and the obese carnitine group had lower level compared to the obese control group (P < 0.05). The obese carnitine group had an increased number of type I muscle fibers and higher mRNA levels of type I fiber-specific myosin heavy chain, regulators of muscle fiber transition and of genes involved in carnitine uptake, fatty acid transport, β-oxidation, angiogenesis, tricarboxylic acid cycle and thermo genesis in M. rectus femoris compared to the other groups (P < 0.05).

CONCLUSION

The results demonstrate that carnitine supplementation to obese Zucker a rat counteracts the obesity-induced muscle fiber transition and restores the muscle oxidative metabolic phenotype. Carnitine supplementation is supposed to be beneficial for the treatment of elevated levels of plasma lipids during obesity or diabetes.

Location-dependent value of pelvic MRI in the preoperative diagnosis of endometriosis

OBJECTIVES

To investigate the value of magnetic resonance imaging (MRI) in the preoperative diagnosis of specific anatomical locations of endometriosis.

STUDY DESIGN

Between July 2008 and April 2011, 152 women (mean age 33.5 ± 6.1 years) with clinical and sonographic suspicion of endometriosis underwent pelvic MRI using T2 and unenhanced T1 sequences with and without fat saturation. Two radiologists interpreted the following regions by consensus according to a standardized protocol: ovaries, vagina, pouch of Douglas, rectosigmoid colon, uterosacral ligament (USL), bladder, peritoneum, and other pelvic regions. The results of MRI were retrospectively correlated with the laparoscopic and histopathologic findings. The main outcome parameters, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, positive likelihood ratio (LR+) and the negative likelihood ratio (LR-), were determined.

RESULTS

Sensitivity, specificity, PPV, NPV, accuracy, positive and the negative likelihood ratio were 87.6%, 84.6%, 94.3%, 70.2%, 86.8%, 5.69 and 0.15 for the pouch of Douglas (vagina: 81.4%, 81.7%, 79.2%, 83.8%, 81.6%, 4.45, 0.23; rectosigmoid colon: 80.2%, 77.5%, 80.2%, 77.5%, 78.9%, 3.56, 0.25; USL: 77.5%, 68.2%, 77.5%, 68.2%, 73.7%, 2.44, 0.33; ovaries: 86.3%, 73.6%, 78.4%, 82.8%, 80.3%, 3.27, 0.19; urinary bladder: 81.0%, 94.7%, 70.8%, 96.9%, 92.8%, 15.15, 0.20; peritoneum: 35.3%, 88.1%, 60.0%, 73.0%, 70.4%, 2.97, 0.73). All endometriotic implants at other localization were detected (abdominal wall in 4, groin in one patient).

CONCLUSIONS

The value of MRI in preoperative diagnosis of endometriosis is dependent on the location of endometriosis. The highest accuracy was found in bladder endometriosis and the lowest in peritoneal endometriosis.

Supplementing obese Zucker rats with niacin induces the transition of glycolytic to oxidative skeletal muscle fibers

In the present study, we tested the hypothesis that niacin increases the oxidative capacity of muscle by increasing the oxidative type I muscle fiber content. Twenty-four obese Zucker rats were assigned to 2 groups of 12 rats that were fed either a control diet (O group) or a diet supplemented with 750 mg/kg diet niacin (O+N group) for 4 wk. In addition, one group of lean rats (L group) was included in the experiment and fed the control diet for 4 wk. Plasma and liver concentrations of TG were markedly greater in obese groups than in the L group but markedly lower in the O+N group than in the O group (P < 0.05). Rats of the O+N group had a higher percentage of oxidative type I fibers and higher mRNA levels of genes encoding regulators of muscle fiber composition (Ppard, Ppargc1a, Ppargc1b), angiogenic factors (Vegfa, Vegfb), and genes involved in fatty acid utilization (Cpt1b, Slc25a20, Slc22a4, Slc22a5, Slc27a1) and oxidative phosphorylation (Cox4i1, Cox6a2) and a higher activity of the mitochondrial oxidative enzyme succinate dehydrogenase in muscle than rats of the O and L groups (P < 0.05). These niacin-induced changes in muscle metabolic phenotype are indicative of an increased capacity of muscle for oxidative utilization of fatty acids and are likely mediated by the upregulation of Ppard, Ppargc1a, and Ppargc1b, which are key regulators of muscle fiber composition, mitochondrial biogenesis, angiogenesis, and genes involved in fatty acid catabolism and oxidative phosphorylation. The increased utilization of fatty acids by muscle might contribute to the strong TG-lowering effect of niacin treatment.

[Systematic literature research for S1 guidelines on sequential medical treatment of rheumatoid arthritis]

BACKGROUND

On behalf of the German association of Rheumatology national experts developed guidelines for the medical treatment of rheumatoid arthritis (RA) based on the EULAR recommendations for the management of RA published in 2010. Current evidence was provided with an update of the systematic literature review (SLR). The methods and results of the SLR are presented in this article.

MATERIALS AND METHODS

An update of the EULAR SLR for the medical treatment of RA was performed from January 2009 to August 2011. The SLR assessed all controlled studies dealing with the outcome in clinical aspects, function and structure of disease modifying treatment of RA.

RESULTS

Out of 6,869 screened publications, 138 articles and 56 abstracts were considered in the development of the German guidelines on the treatment of RA. A modified set of recommendations was approved in a consensus of national experts.

CONCLUSION

A systematic literature research provided current evidence for the German recommendations on the sequential medical treatment of RA.

PTPIP51: a new interaction partner of the insulin receptor and PKA in adipose tissue

AIMS

Our previous experiments revealed an association of PTPIP51 (protein tyrosine phosphatase interacting protein 51) with the insulin signalling pathway through PTP1B and 14-3-3beta. We aimed to clarify the role of PTPIP51 in adipocyte metabolism.

METHODS

Four groups of ten C57Bl/6 mice each were used. Two groups were fed a standard diet; two groups were fed a high-fat diet. Two groups (one high-fat diet and one standard diet) were submitted to endurance training, while the remaining two groups served as untrained control groups. After ten weeks, we measured glucose tolerance of the mice. Adipose tissue samples were analyzed by immunofluorescence and Duolink proximity ligation assay to quantify interactions of PTPIP51 with either insulin receptor (IR) or PKA.

RESULTS

PTPIP51 and the IR and PTPIP51 and PKA, respectively, were colocalized in all groups. Standard diet animals that were submitted to endurance training showed low PTPIP51-IR and PTPIP51-PKA interactions. The interaction levels of both the IR and PKA differed between the feeding and training groups.

CONCLUSION

PTPIP51 might serve as a linking protein in adipocyte metabolism by connecting the IR-triggered lipogenesis with the PKA-dependent lipolysis. PTPIP51 interacts with both proteins, therefore being a potential gateway for the cooperation of both pathways.

[Immunoadsorption in thrombangiitis obliterans: a promising therapeutic option: results of a consecutive patient cohort treated in clinical routine care]

BACKGROUND

Thrombangiitis obliterans or Buerger's disease is a segmental inflammatory disease affecting small and medium-sized veins and arteries, which most often affects young smokers leading to thrombophlebitis and acral ischaemic syndromes, inducing high amputation rates. Based on positive results of a former pilot study we report on our results of immunoadsorption (IA) in clinical routine care, where IA was offered as a treatment option.

PATIENTS AND METHODS

The uncontrolled course of 12 consecutive TAO-patients treated by IA on a series of 5 consecutive days was observed. Follow-up period was 14.1 (ranging from 1-26) months.

RESULTS

Eight patients were treated with one, four patients completed 2 IA-series. In 9 patients an early onset and lasting clinical improvement and an improvement of ischaemia was noted. The intake of pain-relievers (especially opioids) sank drastically. Eight patients returned to work. Retrospectively, in two out of three treatment failures the correct diagnosis of TAO was questionable.

CONCLUSION

IA seems to be a promising treatment option for patients suffering from TAO which should be further evaluated in controlled clinical trials.

Exercise delays neutrophil apoptosis by a G-CSF-dependent mechanism

The aim of the study was to determine whether exercise affects neutrophil apoptosis and to characterize the underlying mechanisms. Using annexin V labeling, neutrophil apoptosis was measured using flow cytometry after various bouts of exercise (marathon run, concentric/eccentric treadmill exercise, moderate/intensive resistance training) and in vitro conditions. Similarly, apoptosis-related markers as death receptors/ligands and mitochondrial membrane potential were detected. Furthermore, concentrations of intracellular free calcium and glutathione were measured using spectrofluorometry. After both marathon run and intensive laboratory exercise tests, neutrophil apoptosis was delayed. Furthermore, neutrophils mitochondrial membrane potential and death receptor/ligand expression were not affected by exercise. Apoptosis delay was accompanied under some exercise conditions by enhanced intracellular calcium transients and decreased glutathione levels. A delay of spontaneous apoptosis in vitro could be induced by incubation of neutrophils in postexercise serum. Heating of postexercise serum abolished the apoptosis delaying effect. In vitro stimulation of resting neutrophils with granulocyte-colony-stimulating factor (G-CSF) and C-reactive protein resulted in apoptosis delay too. Addition of anti-G-CSF antibody to postexercise serum was also effective in reversing its apoptosis-delaying effect. Exercise-induced mobilization of neutrophils is associated with a delay of apoptosis. This fundamental process seems to maintain exercise-induced neutrophilia and to contribute to the alerting and activation of the nonadaptive immune system known from other inflammatory conditions. An important extracellular trigger of apoptosis delay during exercise conditions seems to be G-CSF; intracellular processes may include calcium and redox signaling.

Microvessel proliferation by co-expression of endothelial nestin and Ki-67 is associated with a basal-like phenotype and aggressive features in breast cancer

BACKGROUND

To quantify tumour angiogenesis, microvessel density (MVD) has been widely used. We here present a novel angiogenesis marker, microvessel proliferation (MVP), based on dual immunohistochemical staining of nestin and Ki-67. Immature endothelial cells express nestin, and when co-expressed with the proliferation marker Ki-67, the number of proliferating immature blood vessels can be measured.

MATERIALS AND METHODS

Microvessel proliferation was evaluated in 178 breast cancer samples and estimated by vascular proliferation index (VPI), the ratio between the number of vessels containing proliferating endothelial cells and the total number of immature vessels.

RESULTS

High VPI was strongly associated with several markers of aggressive breast cancer, such as negative oestrogen receptor (ER) status (p = 0.003), high tumour cell proliferation by Ki-67 (p = 0.004), high p53 expression (p = 0.001), and five profiles for the basal-like phenotype (odds ratios (OR); range 3.4-6.3). Also, high VPI was significantly associated with interval detected breast cancer compared with screening detected lesions (p < 0.0005), and adverse outcome in univariate and multivariate survival analysis (p = 0.034 and p = 0.022, respectively).

CONCLUSION

Microvessel proliferation is a novel marker of ongoing angiogenesis and was associated with aggressive tumour features, basal-like phenotypes, interval presentation, and prognosis in this series of breast cancer.

Coil embolization for treatment of vascular complications after nephron-sparing surgery

Nephron-sparing surgery (NSS) is a standard surgical treatment for small renal tumors. We report four patients (aged 35-79 years) with vascular complications within 6 days to 3 months after open NSS. Three patients developed acute symptoms, whereas one was asymptomatic. Computed tomography (CT) in the arterial and venous phase of contrast enhancement was performed for diagnosis, followed by angiography. CT demonstrated a perirenal hematoma in three and an arterial pseudoaneurysm in two cases. Unlike CT, digital subtraction angiography confirmed an arterial pseudoaneurysm in all cases and additionally found an arteriovenous fistula in three. In all cases, angiography-guided coil embolization successfully treated the vascular pathology, while preserving renal function. Clinicians should understand the diagnosis and management of this complication of NSS.

[Early and advanced rheumatoid arthritis. Diagnosis and state of the art therapy strategy]

The diagnosis of rheumatoid arthritis (RA) is often based on classification criteria. In 2010 ACR and EULAR presented new classification criteria for RA which allow patients with a high risk for persistent, chronic and erosive arthritis and therefore fulfill the current definition of RA, to be defined. Therapy of RA should be initiated as early as possible. Methotrexate remains the first-line therapy of RA. In patients showing insufficient response of RA, biological agents have been demonstrated to be an effective second-line therapy. It is essential to define and follow an individual treatment target to obtain remission or low disease activity. This target should be reassessed regularly and treatment should be correspondingly adapted to achieve the target.