Oxidized proportion of muscle coenzyme Q10 increases with age in healthy children.

BACKGROUND: Coenzyme Q10 (CoQ10) is synthesized in most human tissues, with high concentration in the skeletal muscle. CoQ10 functions in the mitochondrial respiratory chain and serves as a potent liphophilic antioxidant in membranes. CoQ10 deficiency impairs mitochondrial ATP synthesis and increases oxidative stress. It has been suggested that plasma CoQ10 status is not a robust proxy for the diagnosis of CoQ10 deficiency. METHODS: We determined the concentration and redox-status of CoQ10 in plasma and muscle tissue from 140 healthy children (0.8-15.3 y) by high-performance liquid chromatography (HPLC) with electrochemical detection. RESULTS: There was no correlation between CoQ10 concentration or redox status between plasma and muscle tissue. Lipid-related CoQ10 plasma concentrations showed a negative correlation with age (Spearman's, P ≤ 0.02), but there was no significant age-related correlation for muscle concentration. In muscle tissue, we found a distinct shift in the redox status in favor of the oxidized proportion with increasing age (Spearman's, P ≤ 0.00001). Reference values for muscle CoQ10 concentration (40.5 ± 12.2 pmol/mg wet tissue) and CoQ10 redox status (46.8 ± 6.8% oxidized within total) were established for healthy children. CONCLUSION: The age-related redox shift in muscle tissue suggests changes in antioxidative defense during childhood. The reference values established here provide a necessary prerequisite for diagnosing early CoQ10 deficiency.

Ecdysone signaling at metamorphosis triggers apoptosis of Drosophila abdominal muscles.

One of the most dramatic examples of programmed cell death occurs during Drosophila metamorphosis, when most of the larval tissues are destroyed in a process termed histolysis. Much of our understanding of this process comes from analyses of salivary gland and midgut cell death. In contrast, relatively little is known about the degradation of the larval musculature. Here, we analyze the programmed destruction of the abdominal dorsal exterior oblique muscle (DEOM) which occurs during the first 24h of metamorphosis. We find that ecdysone signaling through Ecdysone receptor isoform B1 is required cell autonomously for the muscle death. Furthermore, we show that the orphan nuclear receptor FTZ-F1, opposed by another nuclear receptor, HR39, plays a critical role in the timing of DEOM histolysis. Finally, we show that unlike the histolysis of salivary gland and midgut, abdominal muscle death occurs by apoptosis, and does not require autophagy. Thus, there is no set rule as to the role of autophagy and apoptosis during Drosophila histolysis.

The x-ray crystal structure of mannose-binding lectin-associated serine proteinase-3 reveals the structural basis for enzyme inactivity associated with the Carnevale, Mingarelli, Malpuech, and Michels (3MC) syndrome.

The mannose-binding lectin associated-protease-3 (MASP-3) is a member of the lectin pathway of the complement system, a key component of human innate and active immunity. Mutations in MASP-3 have recently been found to be associated with Carnevale, Mingarelli, Malpuech, and Michels (3MC) syndrome, a severe developmental disorder manifested by cleft palate, intellectual disability, and skeletal abnormalities. However, the molecular basis for MASP-3 function remains to be understood. Here we characterize the substrate specificity of MASP-3 by screening against a combinatorial peptide substrate library. Through this approach, we successfully identified a peptide substrate that was 20-fold more efficiently cleaved than any other identified to date. Furthermore, we demonstrated that mutant forms of the enzyme associated with 3MC syndrome were completely inactive against this substrate. To address the structural basis for this defect, we determined the 2.6-Å structure of the zymogen form of the G666E mutant of MASP-3. These data reveal that the mutation disrupts the active site and perturbs the position of the catalytic serine residue. Together, these insights into the function of MASP-3 reveal how a mutation in this enzyme causes it to be inactive and thus contribute to the 3MC syndrome.

Mannan-binding lectin-associated serine protease (MASP)-1 is crucial for lectin pathway activation in human serum, whereas neither MASP-1 nor MASP-3 is required for alternative pathway function.

The lectin pathway of complement is an important component of innate immunity. Its activation has been thought to occur via recognition of pathogens by mannan-binding lectin (MBL) or ficolins in complex with MBL-associated serine protease (MASP)-2, followed by MASP-2 autoactivation and cleavage of C4 and C2 generating the C3 convertase. MASP-1 and MASP-3 are related proteases found in similar complexes. MASP-1 has been shown to aid MASP-2 convertase generation by auxiliary C2 cleavage. In mice, MASP-1 and MASP-3 have been reported to be central also to alternative pathway function through activation of profactor D and factor B. In this study, we present functional studies based on a patient harboring a nonsense mutation in the common part of the MASP1 gene and hence deficient in both MASP-1 and MASP-3. Surprisingly, we find that the alternative pathway in this patient functions normally, and is unaffected by reconstitution with MASP-1 and MASP-3. Conversely, we find that the patient has a nonfunctional lectin pathway, which can be restored by MASP-1, implying that this component is crucial for complement activation. We show that, although MASP-2 is able to autoactivate under artificial conditions, MASP-1 dramatically increases lectin pathway activity at physiological conditions through direct activation of MASP-2. We further demonstrate that MASP-1 and MASP-2 can associate in the same MBL complex, and that such cocomplexes are found in serum, providing a scenario for transactivation of MASP-2. Hence, in functional terms, it appears that MASP-1 and MASP-2 act in a manner analogous to that of C1r and C1s of the classical pathway.

Induction of diaphragmatic nitric oxide synthase after endotoxin administration in rats: role on diaphragmatic contractile dysfunction.

Nitric oxide (NO), a free radical that is negatively inotropic in the heart and skeletal muscle, is produced in large amounts during sepsis by an NO synthase inducible (iNOS) by LPS and/or cytokines. The aim of this study was to examine iNOS induction in the rat diaphragm after Escherichia Coli LPS inoculation (1.6 mg/kg i.p.), and its involvement in diaphragmatic contractile dysfunction. Inducible NOS protein and activity could be detected in the diaphragm as early as 6 h after LPS inoculation. 6 and 12 h after LPS, iNOS was expressed in inflammatory cells infiltrating the perivascular spaces of the diaphragm, whereas 12 and 24 h after LPS it was expressed in skeletal muscle fibers. Inducible NOS was also expressed in the left ventricular myocardium, whereas no expression was observed in the abdominal, intercostal, and peripheral skeletal muscles. Diaphragmatic force was significantly decreased 12 and 24 h after LPS. This decrease was prevented by inhibition of iNOS induction by dexamethasone or by inhibition of iNOS activity by N(G)-methyl-L-arginine. We conclude that iNOS was induced in the diaphragm after E. Coli LPS inoculation in rats, being involved in the decreased muscular force.

The effect of aging on anaerobic and aerobic enzyme activities in human skeletal muscle.

The effect of aging on metabolic enzyme activity remains controversial, possibly due to physical activity differences. We examined the effect of aging on the enzyme activity for anaerobic and aerobic pathways in nonweight-bearing human skeletal muscle from relatively sedentary males. The muscle obliquus internus abdominis was analyzed for anaerobic (creatine kinase, adenylate kinase, and lactate dehydrogenase) and aerobic (2-oxoglutarate dehydrogenase and carnitine palmitoyltransferase) enzyme activities in two groups: middle-aged (29-54 years) and older (61-74 years) adults. All enzyme activities were lower in older versus middle-aged adults when results were expressed as muscle wet weight (p <.05). When activity was expressed relative to the protein content, only lactate dehydrogenase remained significantly lower in older versus middle-aged adults (p <.001). In conclusion, some of the reduction in muscle performance in older adults may be due to lower activity of the anaerobic and aerobic enzymes as well as protein content, not solely due to a decrease in physical activity.

Stromelysin-1 (matrix metalloproteinase-3) and tissue inhibitor of metalloproteinase-3 are overexpressed in the wall of abdominal aortic aneurysms.

BACKGROUND: Atherosclerosis is implicated in the pathogenesis of abdominal aortic aneurysm (AAA) but more often causes aortic occlusive disease (AOD). The matrix metalloproteinases (MMPs) degrade extracellular matrix and may play a central role in the pathogenesis of AAA. The aim of this study was to examine differences in the patterns of MMP and MMP inhibitor expression between AAA and AOD. METHODS AND RESULTS: The expression of mRNA for 14 MMPs and 4 tissue inhibitors of metalloproteinases (TIMPs) was estimated in samples of aortic wall from 8 patients with AAA and 8 with AOD using the reverse-transcriptase polymerase chain reaction with a synthetic multicompetitor standard. AAA wall expressed significantly more stromelysin-1 (MMP-3) (mean log(10) ratio [copy enzyme cDNA/copy GAPDH cDNA], -1.9; range, -3.3 to -0.7) than the AOD wall (mean, 4; range, -5.7 to -2.4), P<0.005. TIMP-3 expression was significantly higher in AAA (mean, -1.7; range, -2.9 to -1.0) than AOD (mean, -3.6; range, -5.7 to -1.8), P<0.01. Expression of 8 other MMPs (1, 2, 7, 9, 11, 12, 14, and 17) was detected and was similar in AAA and AOD. Expression of the remaining 5 MMPs (-8, -10, -13, -15, and -16) was not detected in any of the samples. CONCLUSIONS: Both AAA and AOD walls express similar levels of a wide range of MMPs, including cell membrane-bound MT-MMPs. Stromelysin-1 (MMP-3) and TIMP-3 were, however, over expressed in the AAA samples and may be involved aneurysm pathogenesis. Stromelysin-1 could provide a target for pharmacological inhibition.

Role of TIMP-2 in fascia transversalis on development of inguinal hernias.

The exact reason for the development of inguinal hernia has not been completely determined. However, it is known that the fascia transversalis (FT) is one of the structures preventing development of hernias. In the etiology of the inguinal hernia, disorders in collagen metabolism have been proposed, and the role of metalloproteinases in remodeling the collagen has recently been of great importance. We could not encounter any study where the role of metalloproteinase inhibitors was evaluated in inguinal hernia. We obtained samples of FT from patients with direct and indirect hernia and used an immunohistochemical method to determine tissue inhibitor of metalloproteinase-2 (TIMP-2) expression. In the study group, samples of FT were taken during the operation from 45 patients, of which 35 were indirect and 10 were direct inguinal hernias. In the control group, samples of FT from various abdominal incisions were also taken from 45 patients with no hernia and operated upon for another pathology. TIMP-2 scores of a direct inguinal hernia were significantly less than those of the control group. However, no difference has been found between the TIMP-2 scores of an indirect inguinal hernia and those of the control group. Decreased TIMP-2 scores in patients with a direct inguinal hernia, compared with both the indirect inguinal hernia group and the control group, explain the reason for the increase in matrix metalloproteinase-2 (MMP-2) that has been proposed in some studies. Therefore, it can be expressed that a decreased activity of TIMP-2 plays a role in inguinal hernia development.

Increased protein kinase C theta in skeletal muscle of diabetic patients.

In this study we have investigated whether protein kinase C (PKC) protein and activity are increased in skeletal muscle of human diabetic patients. The protein content of different PKC isoforms (beta, Theta, epsilon, delta, mu, and zeta) in the particulate fraction was measured, using Western analysis, in human rectus abdominus skeletal muscle from obese (hyperinsulinemic, normoglycemic) and obese diabetic (hyperinsulinemic, hyperglycemic) subjects. PKC Theta protein content was significantly higher in the particulate fraction of muscle from diabetic patients compared with the nondiabetic controls. PKC Theta was immunoprecipitated and its activity was measured in muscle from diabetic and nondiabetic controls. There was a significant increase in PKC Theta activity in muscle from diabetic patients compared with muscle from nondiabetic controls. Therefore, both PKC Theta protein content and activity were significantly increased in the particulate fraction in muscle from diabetic patients, suggesting the involvement of this isoform in diabetes. Most of the PKC Theta protein was found in the cytosol. There was no change in cytosolic PKC Theta protein content in muscle from diabetic patients compared with muscle from nondiabetic controls. Thus, the increase in particulate-associated PKC Theta was likely due to translocation and activation rather than an increase in protein mass.

Fiber architecture of canine abdominal muscles.

During respiration, abdominal muscles experience loads, not only in the muscle-fiber direction but also transverse to the fibers. We wondered whether the abdominal muscles exhibit a fiber architecture that is similar to the diaphragm muscle, and, therefore, we chose two adjacent muscles: the internal oblique (IO), with about the same muscle length as the diaphragm, and the transverse abdominis (TA), which is twice as long as the diaphragm. First, we used acetylcholinesterase staining to examine the distribution of neuromuscular junctions on both surfaces of the TA and IO muscles in six dogs. A maximum of four irregular bands of neuromuscular junctions crossed the IO, and as many as six bands crossed the TA, which is consistent with a discontinuous fiber architecture. In six additional dogs, we examined fiber architecture of these muscles by microdissecting 103 fascicles from the IO and 139 from the TA. Each fascicle contained between 20 and 30 muscle fibers. The mean length of nonspanning fibers (NSF) ranged from 2.8 +/- 0.3 cm in the IO to 4.3 +/- 0.5 cm in the TA, and the mean length of spanning fibers ranged from 4.3 +/- 0.5 cm in the IO to 7.6 +/- 1.4 cm in the TA. NSF accounted for 89.6 +/- 1.5% of all fibers dissected from the IO and 99.1 +/- 0.2% of all fibers dissected from the TA. The percentage of NSF with both ends tapered was 6.2 +/- 1.0 and 41.0 +/- 2.3% for IO and TA, respectively. These data show that fiber architecture in either IO or TA is discontinuous, with much more short-tapered fibers in the TA than in the IO. When abdominal muscles are submaximally activated, as during both normal expiration and maximal expiratory efforts, muscle force could be transmitted to the cell membrane and to the extracellular intramuscular connective tissue by shear linkage, presumably via structural transmembrane proteins.

Role of nitric oxide in vasodilation in upstream muscle during intermittent pneumatic compression.

This study investigated the dosage effects of nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on intermittent pneumatic compression (IPC)-induced vasodilation in uncompressed upstream muscle and the effects of IPC on endothelial NOS (eNOS) expression in upstream muscle. After L-NMMA infusion, mean arterial pressure increased by 5% from baseline (99.5 +/- 18.7 mmHg; P < 0.05). Heart rate and respiratory rate were not significantly affected. One-hour IPC application on legs induced a 10% dilation from baseline in 10- to 20-microm arterioles and a 10-20% dilation in 21- to 40 microm arterioles and 41- to 70-microm arteries in uncompressed cremaster muscle. IPC-induced vasodilation was dose dependently reduced, abolished, or even reversed by concurrently infused L-NMMA. Moreover, expression of eNOS mRNA in uncompressed cremaster muscle was upregulated to 2 and 2.5 times normal at the end of 1- and 5-h IPC on legs, respectively, and the expression of eNOS protein was upregulated to 1.8 times normal. These increases returned to baseline level after cessation of IPC. The results suggest that eNOS plays an important role in regulating the microcirculation in upstream muscle during IPC.

Radioimmunoassay of creatine kinase: studies on the skeletal muscle and cardiac muscle enzyme (MM and MB isoenzymes) in serum and neuromuscular tissues.

A radioimmunoassay, specific for the isoenzymes of creatine kinase containing the M subunit of the enzyme (MM and MB creatine kinase), was employed to determine total creatine kinase concentrations in serum and neuromuscular tissues independently of the state of activity of the enzyme. This technique provides a method for the detection of inactive enzyme, which could be produced by inhibitors of the enzyme or by mutations involving the active site of the enzyme. A series of experiments were carried out to compare the amount of creatine kinase in various samples as assessed by normal enzyme kinetic procedures and by radioimmunoassay. The two techniques yielded equivalent results in all situations tested. Samples included serum from normal subjects and subjects with genetic and acquired diseases of muscle and also extracts from skeletal and cardiac muscle. Small quantities of immunoreactive enzyme were found in nervous tissue and assessed in terms of the incidence of the M subunit.

Lipoprotein-lipase activity in subcutaneous, adipose tissue in healthy subjects: variation of activity in a population of 60-year-old men.

The lipoprotein-lipase activity (LPLA) in the abdominal, subcutaneous, adipose tissue was studied in a random sample (n = 69) of 60-year-old men. A new method for the quantification of LPLA was applied. The mean value was 67 mU/g when expressed per gram (wet weight) of adipose tissue. Several subjects within the lower part of the range of adipose-tissue LPLA values had low concentrations of serum-triglycerides (S-TG). There was no correlation between the LPLA and S-TG concentrations in the fasting state. Among the 69 subjects, four had newly detected diabetes mellitus and had significantly lower LPLA in the adipose tissue than the control group. The fat-cell size and the LPLA per gram of adipose tissue were not correlated. Thus, obesity without diabetes mellitus does not imply a low LPLA concentration in adipose tissue. The variation of the concentration of adipose-tissue LPLA in the fasting state in this population was explained only to a minor extent by the variation of S-insulin and blood-glucose parameters, when analysed statistically by a stepwise multiple-regression technique.

The effects of chronically increased intra-abdominal pressure on the rabbit diaphragm.

BACKGROUND: Diaphragmatic muscular remodeling is caused by various conditions and was mainly studied in pulmonary pathologies and chronic alterations of intra-thoracic pressure. We investigate the effect of the chronically increased intra-abdominal pressure (IAP) on the diaphragm by morphological and biochemical analysis. METHODS: Thirty rabbits were divided into control and study groups. IAP was increased in group B to 12 mmHg for 2 months. The left hemidiaphragm underwent morphological, while the right underwent biochemical analysis. RESULTS: In H&E, all fibers were normal. ATPase analysis demonstrated that type I fibers show no differences between groups. Type ΙΙ(Α) were decreased (p = 0.016) while type ΙΙ(Β/X) fibers were increased (p = 0.025) in group B. Fibers with resistance to fatigue were decreased in group B (p = 0.024). In group B, biochemical activity for glutathione reductase (p = 0.004), glutathione peroxidase (p = 0.021), protein carbonylation (0.029), lipid peroxidation (p = 0.005), and balance of preoxidative-antioxidative factors (p = 0.006) was increased. CONCLUSIONS: Chronically increased IAP induces alterations to the rabbit diaphragm. Adaptation, equivalent to strenuous contraction, transforms the diaphragm to be functionally more efficient toward workload but makes it vulnerable against oxidative stress.

Crude lipoxygenase from pig muscle: partial characterization and interactions of temperature, NaCl and pH on its activity.

Crude lipoxygenase (LOX) was extracted from fresh pig bacon belly and studied of partial characteristics. The interactions of temperature, sodium chloride (NaCl) and pH on LOX activity were investigated by response surface methodology (RSM). Kinetic studies indicated that the Michaelis constant (K(m)) and maximum velocity (V(max)) for LOX activity using linoleic acid as substrate were 68 µM and 0.26 U/min at 20°C, respectively. The optimal conditions for this reaction were: substrate concentration 3.47 mM, reaction temperature 39°C and pH ≧9.0. The NaCl critical value for LOX activity was 3.0% (w/w) at 20°C, above which the LOX activity began to decrease. Temperature had significant interactions (p<0.05) with NaCl and pH. The temperature critical value decreased with NaCl content increasing, while increased with pH increasing. These indicated that LOX activity and enzyme-catalyzed lipid oxidation in dry-cured meat products could be regulated by controlling process factors during the processing.

[Enzymatic study of muscle fibers of the antero-lateral wall of the abdomen in man: functional interpretation]. / Etude enzymatique des fibres des muscles de la paroi antéro-latérale de l'abdomen chez l'homme: interprétation fonctionnelle.

After a recall of muscular histo-enzymology, the authors expose the results of an analysis of the antero-lateral muscles of the abdomen. They establish a predominance of the muscular fibers, type I, that are tonic as compared with the muscular fibers, type II, that are phasic. Thus the role of support and of maintenance of the intra-peritoneal pressure by these muscles is confirmed. The tonic characteristic is also important for the functional reeducation and the electrotherapy of the abdominal wall.

Histochemical types and sizes of fibers in the rectus abdominis muscle of guinea pig: adaptive response to pregnancy.

Effects of pregnancy stimulation upon histochemically assessed myofibrillar ATPase and muscle fiber diameters were analysed in the rectus abdominis (RA) muscle of guinea pig. Samples of the muscle were taken at 30, 40, 50, 60, and 70 days of pregnancy and compared with samples of the same muscle taken from nonpregnant guinea pigs. Changes in muscle fiber proportions were noted through the course of pregnancy. Starting from 50 days of gestation an increase in type I fibers and a decrease in type IIB fibers were noted. Increase in muscle fiber diameters was also observed in type I, IIA, and IIB fibers. In addition, the RA muscle of the male guinea pig was compared with that of the female guinea pig and showed more type IIA and less type IIB fibers and all the three fiber types were larger than those of the female.