Muscle mitochondrial metabolism and calcium signaling impairment in patients treated with statins

The most common and problematic side effect of statins is myopathy. To date, the patho-physiological mechanisms of statin myotoxicity are still not clearly understood. In previous studies, we showed that acute application in vitro of simvastatin caused impairment of mitochondrial function and dysfunction of calcium homeostasis in human and rat healthy muscle samples. We thus evaluated in the present study, mitochondrial function and calcium signaling in muscles of patients treated with statins, who present or not muscle symptoms, by oxygraphy and recording of calcium sparks, respectively. Patients treated with statins showed impairment of mitochondrial respiration that involved mainly the complex I of the respiratory chain and altered frequency and amplitude of calcium sparks. The muscle problems observed in statin-treated patients appear thus to be related to impairment of mitochondrial function and muscle calcium homeostasis, confirming the results we previously reported in vitro.

[The rehabilitation cares at the lepers]

Leprosy elimination (<1/100 000) is almost reached all around the world, although, but disabled people are still a lot, and they need rehabilitation as soon as possible. The different lesions (neurological, dermatologic and joint) must be treated in order to protect from handicap. Physical rehabilitation medicine can help with a global and polyvalent coverage. Therapeutic education and reinsertion are an important part.

[Cephalometric study of the velocardiofacial syndrome: Impact of dysmorphosis on phonation]

INTRODUCTION

Velopharyngeal insufficiency is a frequent sign of the velocardiofacial syndrome (VCFS) but its origins are not well-documented. Our aim was to establish a correlation between this functional disorder and regional morphological anomalies.

PATIENTS AND METHODS

Twenty-seven of 36 patients presenting with VCFS could be included retrospectively. We measured cavum depth and velum length on lateral orthodontic X-rays, and assessed the relationship between these two measures. We compared these measures to those of reference populations. Postoperative phonation was assessed with an aerophonoscope.

RESULTS

The patients presented with a short velum and a deep cavum. Cranium base and upper cervical spine were malformed in 22 of the 27 patients. Seventeen of the 23 assessed patients (66%) improved their phonation after surgery.

DISCUSSION

Our data suggests that velopharyngeal insufficiency in VCFS could be the result of a more global craniospinal growth disorder the functional consequences of which remain unclear. The frequent association of morphological anomalies with mental retardation is probably responsible for the failure to normalize phonation.

Intramyocellular lipid accumulation is associated with permanent relocation ex vivo and in vitro of fatty acid translocase (FAT)/CD36 in obese patients

AIMS/HYPOTHESIS

Intramyocellular lipids (IMCL) accumulation is a classical feature of metabolic diseases. We hypothesised that IMCL accumulate mainly as a consequence of increased adiposity and independently of type 2 diabetes. To test this, we examined IMCL accumulation in two different models and four different populations of participants: muscle biopsies and primary human muscle cells derived from non-obese and obese participants with or without type 2 diabetes. The mechanism regulating IMCL accumulation was also studied.

METHODS

Muscle biopsies were obtained from ten non-obese and seven obese participants without type 2 diabetes, and from eight non-obese and eight obese type 2 diabetic patients. Mitochondrial respiration, citrate synthase activity and both AMP-activated protein kinase and acetyl-CoA carboxylase phosphorylation were measured in muscle tissue. Lipid accumulation in muscle and primary myotubes was estimated by Oil Red O staining and fatty acid translocase (FAT)/CD36 localisation by immunofluorescence.

RESULTS

Obesity and type 2 diabetes are independently characterised by skeletal muscle IMCL accumulation and permanent FAT/CD36 relocation. Mitochondrial function is not reduced in type 2 diabetes. IMCL accumulation was independent of type 2 diabetes in cultured myotubes and was correlated with obesity markers of the donor. In obese participants, membrane relocation of FAT/CD36 is a determinant of IMCL accumulation.

CONCLUSIONS/INTERPRETATION

In skeletal muscle, mitochondrial function is normal in type 2 diabetes, while IMCL accumulation is dependent upon obesity or type 2 diabetes and is related to sarcolemmal FAT/CD36 relocation. In cultured myotubes, IMCL content and FAT/CD36 relocation are independent of type 2 diabetes, suggesting that distinct factors in obesity and type 2 diabetes contribute to permanent FAT/CD36 relocation ex vivo.

Combined effects of hypoxia and endurance training on lipid metabolism in rat skeletal muscle

AIM

To determine whether endurance training can counterbalance the negative effects of hypoxia on mitochondrial phosphorylation and expression of the long chain mitochondrial fatty acid transporter muscle carnitine palmitoyl transferase 1 (mCPT-1).

METHODS

Male Wistar rats were exposed either to hypobaric hypoxia (at a simulated altitude of approximately 4000 m, PIO(2) approximately 90 mmHg) or to normoxia (sea level) for 5 weeks. In each environment, rats were randomly assigned to two groups. The trained group went through a 5-week endurance training programme. The control group remained sedentary for the same time period. Muscle fatty acid oxidation capacity was evaluated after the 5-week period on isolated mitochondria prepared from quadriceps muscles with the use of palmitoylcarnitine or pamitoylCoA + carnitine.

RESULTS

Chronic hypoxia decreased basal (V(0), -31% with pamitoylCoA + carnitine and -21% with palmitoylcarnitine, P < 0.05) and maximal (V(max), -31% with pamitoylCoA + carnitine, P < 0.05) respiration rates, hydroxyacylCoA dehydrogenase activity (-48%, P < 0.05), mCPT-1 activity index (-34%, P < 0.05) and mCPT-1 protein content (-34%, P < 0.05). Five weeks of endurance training in hypoxia brought V(0), mCPT-1 activity index and mCPT-1 protein content values back to sedentary normoxic levels. Moreover, in the group trained in hypoxia, V(max) reached a higher level than in the group that maintained a sedentary lifestyle in normoxia (24.2 nmol O(2). min(-1) . mg(-1) for hypoxic training vs. 19.9 nmol O(2) . min(-1) . mg(-1) for normoxic sedentarity, P < 0.05).

CONCLUSION

Endurance training can attenuate chronic hypoxia-induced impairments in mitochondrial fatty acid oxidation. This training effect seems mostly mediated by mCPT-1 activity rather than by mCPT-1 content.

Cost-sparing effect of twice-weekly targeted endurance training in type 2 diabetics: a one-year controlled randomized trial

OBJECTIVE

We evaluated the effects of targeted, moderate endurance training on healthcare cost, body composition and fitness in type 2 diabetes patients routinely followed within the French healthcare system.

DESIGN AND METHODS

A total of 25 type 2 diabetic patients was randomly assigned to one of two groups: 13 underwent a training programme (eight sessions, followed by training twice a week for 30-45 minutes at home at the level of the ventilatory threshold [V(T)]); and 12 received their usual routine treatment. Both groups were followed for one year to evaluate healthcare costs, exercise effectiveness and a six-minute walking test.

RESULTS

The training prevented loss of maximum aerobic capacity, which decreased slightly in the untrained group (P=0.014), and resulted in a higher maximum power output (P=0.041) and six-minute walking distance (P=0.020). The Voorrips activity score correlated with both V(O2max) (r=0.422, P<0.05) and six-minute walking distance (r=0.446, P<0.05). Changes in V(O2max) were negatively correlated with changes in body weight (r=0.608, P<0.01). Training decreased the insulin-resistance index (HOMA-IR) by 26% (P<0.05). Changes in percentages of fat were correlated to changes in waist circumference (r=0.436, P<0.05). The total healthcare cost was reduced by 50% in the trained group (euro 1.65+/-1 per day versus euro 3.00+/-1.47 per day in the untrained group; P<0.02) due to fewer hospitalizations (P=0.05) and less use of sulphonylureas (P<0.05).

CONCLUSION

Endurance training at V(T) level prevented the decline in aerobic working capacity seen in untrained diabetics over the study period, and resulted in a marked reduction in healthcare costs due to less treatments and fewer hospitalizations.

Exercise calorimetry in sedentary patients: procedures based on short 3 min steps underestimate carbohydrate oxidation and overestimate lipid oxidation

OBJECTIVES

Among exercise calorimetry tests designed for calculating the respective part of carbohydrates and lipids oxidized at exercise, some use 6 min steps and others use 3 min steps. Is this last method, which has been validated in healthy subjects, still accurate in very sedentary patients, who need more time to reach a steady state in respiratory gas exchanges?

METHODS

We compared data obtained with calorimetry (RER and indicators of substrate oxidation) performed on the 2nd-3rd min and the 5th-6th min of each step of a protocol using four 6-min submaximal steps in 17 sedentary subjects (mean age: 51 years) including seven type 2 diabetics and six obese persons.

RESULTS

Respiratory exchange ratio (RER) measured with the 3 min steps procedure are well correlated with the 6 min procedure in sedentary patients (r=0.928). However, a Bland-Altman analysis indicated an average underestimation of RER with 3 min steps (-0.0138). Moreover, we observed an average underestimation of carbohydrate oxidation rates of 70.1 mg/min with the 3 min steps procedure. On the contrary, as to lipid oxidation, we measured an average overestimation of 16.2 mg/min. Furthermore, carbohydrate and lipid oxidation rates measured with the 3 min steps procedure are well correlated with the 6 min steps procedure. Moreover, there was an average overestimation of the point at cross over with 3 min steps (+3.29 Watts). For lipox max point (power at which the increase in lipid oxidation induced by the increasing workload reaches a maximum), we observed an average underestimation with 3 min steps (-1.88 Watt). Although the differences between respectively mean values in cross over point and lipox max point between the two protocols are weak, a Bland-Altman analysis indicated more relevant discrepancies in many subjects between the two protocols.

CONCLUSION

In very sedentary patients undergoing such tests for targeting exercise prescription, the 3-min procedure appears to be too short for performing an accurate calorimetry and we rather recommend the protocol using 6-min steps.

[Late diagnosis of a McArdle disease's case (type V glycogenosis)]

McArdle's disease is a metabolic myopathy characterized by a myophosphorylase deficiency resulting in an inability to degrade glycogen stores. We report the case of a 48 years old patient who complained since adolescence of rest and exercise myalgias and presented a chronic increased plasma creatine kinase activity. First, a maximal exercise test was performed. This test demonstrated a quasi lack of rise of respiratory exchange ratio and of blood lactate, possibly due to a glycogenolytic/glycolytic pathway deficiency. Second, a biopsy of vastus lateralis muscle was performed using Bergström needle. As expected, the analysis of mitochondrial function was normal. The in vitro screening test of the glycogenolysis/glycolysis pathway showed a lack of lactate production in presence of glycogen substrate. The study of muscular metabolism of glycogen revealed a glycogen accumulation and a decrease of active and total phosphorylase activities. These data allowed us to diagnose a type V glycogenosis, or McArdle's disease. The patient appeared heterozygous for the most frequent mutation (p.R50X).

Effects of a Supplementation during Exercise and Recovery

The present study was designed to investigate whether a protein hydrolysate enriched in branched chain amino acids and antioxidants, trace and mineral elements, and vitamins would affect performance and fatigue. Eighteen sportsmen underwent testing before and after 28 days supplementation with either treatment in protein hydrolysate or placebo. Testing included exhaustive aerobic and anaerobic exercises with determination of blood lactate concentration through exercise and recovery and antioxidant status, but also measurements of maximal oxidative capacity (V. (max)) and citrate synthase activity (CS) from a resting muscle biopsy. Protein hydrolysate resulted in a significant decrease in fatigue indices, without affecting performances. A significant increase in enzymatic antioxidant and a decrease in oxidative damage were observed at rest after treatment but not with a placebo. Decrease in maximal blood lactate and improvement of blood lactate removal were only observed after protein hydrolysate treatment. Furthermore, CS increased significantly, whereas no change was observed in V. (max). In conclusion, this protein hydrolysate treatment induced adaptations that may promote a decrease in fatigue during exercises, potentially explained by changes in parameters used to represent oxidative damage and antioxidant status at rest and changes in lactate metabolism.

Metabolic training: new paradigms of exercise training for metabolic diseases with exercise calorimetry targeting individuals

For patients with metabolic diseases, as with other diseases, exercise training is a fully recognized therapy. Such training helps obese patients stabilize weight after slimming. For patients with type 2 diabetics, it is both a prevention and a glucose-lowering treatment and reduces health care costs. We propose a targeted training for individuals at the level of maximal lipid oxidation (LIPOXmax) with a protocol of exercise calorimetry (four 6-min workloads) based on Brooks and Mercier's crossover concept. Calorimetric interpretation of gas exchange at the fifth and sixth minutes of each stage shows a bell-shaped curve for lipid oxidation that peaks at LIPOXmax, a point that varies considerably among individuals. As well, glucose oxidation is a linear function of power (carbohydrate cost of the watt). Such a calculation predicts fairly actual lipid oxidation over 45 min at the same level. Other protocols, with 3-min workloads used in sports medicine, are not reliable for patients with metabolic diseases. For obese adults and teenagers, as well as those with type 2 diabetes, 2 months' training at the LIPOXmax (three sessions at 45 min per week) results in a net loss of fat mass, with preserved fat-free mass, and increased ability to oxidize lipids. At the end of this period, training can be "re-targeted" to be more effective and, possibly, associated with other strategies with stronger exercise intensities. Therefore, metabolic training is a viable option for patients with metabolic diseases, but the full concept is still evolving. However, the major challenge remains to transform inactive individuals into active ones.

X-Y-autosome translocation, chromosome compaction, NOR expression and heterochromatin insulation in the Scarabaeid beetle Dynastes hercules hercules

The karyotype of the giant beetle Dynastes hercules hercules is composed of only 16 autosomes and large sex chromosomes. Meiotic studies in the males showed that a large part of the sex chromosomes undergo synapsis at pachynema similarly to autosomes, demonstrating that both derived from an autosome-gonosome translocation. Therefore, karyotype formula is 18,neoXY. The heterochromatisation of the neoX short arm at pachynema indicates that it corresponds to the ancestral X. It carries the nucleolar organizer region (NOR) in its proximal part, which is undercondensed, especially in male mitotic and meiotic cells. In female mitotic cells, both NOR staining and undercondensation were more difficult to observe in the neoX short arms. In somatic interphase nuclei, NOR expression strongly varies with the sex. Two separated compact groups of silver dots were observed in female nuclei, while a single dispersed and large group of silver deposit exists in the males. Both the lower condensation and the higher NOR expression of the single neoX of the males, compared to each of the two neoXs of the females, is interpreted to be a consequence of dosage compensation, a mechanism not yet described in Coleoptera. In mammals as well as in Coleoptera, the carriers of gonosome-autosome translocations not exhibiting deleterious phenotypes show constitutive heterochromatin at the autosome-gonosome junction. Thus, heterochromatin may play an important universal role by clearly separating chromosome segments with different regulations of gene expression, such as inactivation or dosage compensation of the X chromosome on the one side and a conventional autosomal structure on the other side.