Neuromuscular electrical stimulation improves skeletal muscle regeneration through satellite cell fusion with myofibers in healthy elderly subjects

The aim of this study was to determine whether neuromuscular electrical stimulation (NMES) affects skeletal muscle regeneration through a reduction of oxidative status in satellite cells of healthy elderly subjects. Satellite cells from the vastus lateralis skeletal muscle of 12 healthy elderly subjects before and after 8 wk of NMES were allowed to proliferate to provide myogenic populations of adult stem cells [myogenic precursor cells (MPCs)]. These MPCs were then investigated in terms of their proliferation, their basal cytoplasmic free Ca2+concentrations, and their expression of myogenic regulatory factors ( PAX3, PAX7, MYF5, MYOD, and MYOG) and micro-RNAs (miR-1, miR-133a/b, and miR-206). The oxidative status of these MPCs was evaluated through superoxide anion production and superoxide dismutase and glutathione peroxidase activities. On dissected single skeletal myofibers, the nuclei were counted to determine the myonuclear density, the fiber phenotype, cross-sectional area, and tension developed. The MPCs obtained after NMES showed increased proliferation rates along with increased cytoplasmic free Ca2+concentrations and gene expression of MYOD and MYOG on MPCs. Muscle-specific miR-1, miR-133a/b, and miR-206 were upregulated. This NMES significantly reduced superoxide anion production, along with a trend to reduction of superoxide dismutase activity. The NMES-dependent stimulation of muscle regeneration enhanced satellite cell fusion with mature skeletal fibers. NMES improved the regenerative capacity of skeletal muscle in elderly subjects. Accordingly, the skeletal muscle strength and mobility of NMES-stimulated elderly subjects significantly improved. NMES may thus be further considered for clinical or ageing populations.

NEW & NOTEWORTHY The neuromuscular electrical stimulation (NMES) effect on skeletal muscle regeneration was assessed in healthy elderly subjects for the first time. NMES improved the regenerative capacity of skeletal muscle through increased myogenic precursor cell proliferation and fusion with mature myofibers. The increased cytoplasmic free Ca2+concentration along with MYOD, MYOG, and micro-RNA upregulation could be related to reduced O2·−production, which, in turn, favors myogenic regeneration. Accordingly, the skeletal muscle strength of NMES-stimulated lower limbs of healthy elderly subjects improved along with their mobility.

Role of p66shc in skeletal muscle function

p66shc is a growth factor adaptor protein that contributes to mitochondrial ROS production. p66shc is involved in insulin signaling and its deletion exerts a protective effect against diet-induced obesity. In light of the role of skeletal muscle activity in the control of systemic metabolism and obesity, we investigated which is the contribution of p66shc in regulating muscle structure and function. Here, we show that p66shc^−/− muscles are undistinguishable from controls in terms of size, resistance to denervation-induced atrophy, and force. However, p66shc^−/− mice perform slightly better than wild type animals during repetitive downhill running. Analysis of the effects after placing mice on a high fat diet (HFD) regimen demonstrated that running distance is greatly reduced in obese wild type animals, but not in overweight-resistant p66shc^−/− mice. In addition, muscle force measured after exercise decreases upon HFD in wild type mice while p66shc^−/− animals are protected. Our data indicate that p66shc affect the response to damage of adult muscle in chow diet, and it determines the maintenance of muscle force and exercise performance upon a HFD regimen.

FoxO-dependent atrogenes vary among catabolic conditions and play a key role in muscle atrophy induced by hindlimb suspension

KEY POINTS

Muscle atrophy is a debilitating condition that affects a high percentage of the population with a negative impact on quality of life. Dissecting the molecular level of the atrophy process, and the similarities/dissimilarities among different catabolic conditions, is a necessary step for designing specific countermeasures to attenuate/prevent muscle loss. The FoxO family transcription factors represent one of the most important regulators of atrophy programme stimulating the expression of many atrophy-related genes. The findings of the present study clearly indicate that the signalling network controlling the atrophy programme is specific for each catabolic condition.

ABSTRACT

Muscle atrophy is a complex process that is in common with many different catabolic diseases including disuse/inactivity and ageing. The signalling pathways that control the atrophy programme in the different disuse/inactivity conditions have not yet been completely dissected. The inhibition of FoxO is considered to only partially spare muscle mass after denervation. The present study aimed: (i) to determine the involvement of FoxOs in hindlimb suspension disuse model; (ii) to define whether the molecular events of protein breakdown are shared among different unloaded muscles; and finally (iii) to compare the data obtained in this model with another model of inactivity such as denervation. Both wild-type and muscle-specific FoxO1,3,4 knockout (FoxO1,3,4^-/- ) mice were unloaded for 3 and 14 days and muscles were characterized by functional, morphological, biochemical and molecular assays. The data obtained show that FoxOs are required for muscle loss and force drop during unloading. Moreover, we found that FoxO-dependent atrogenes vary in different unloaded muscles and that they diverge from denervation. The findings of the present study clearly indicate that the signalling network that controls the atrophy programme is specific for each catabolic condition.

The Regenerative Potential of Female Skeletal Muscle upon Hypobaric Hypoxic Exposure

Aim: The aim of this study was to determine whether a 14-day trekking expeditions, in high altitude hypoxic environment, triggers redox disturbance at the level of satellite cells (adult stem cells) in young women.

Methods: We collected muscle biopsies from Vastus Lateralis muscle for both single fiber analysis and satellite cells isolation. The samples collected before (PRE-Hypoxia) and after (POST-Hypoxia) the trekking in the Himalayas were compared. Satellite cells were investigated for oxidative stress (oxidant production, antioxidant enzyme activity, and lipid damage), mitochondrial potential variation, gene profile of HIF, and myogenic transcription factors (Pax7, MyoD, myogenin), and miRNA expression (miR-1, miR-133, miR-206).

Results: The nuclear domain analysis showed a significant fusion and consequent reduction of the Pax7⁺ satellite cells in the single mature fibers. The POST-Hypoxia myoblasts obtained by two out of six volunteers showed high superoxide anion production and lipid peroxidation along with impaired dismutase and catalase and mitochondrial potential. The transcription profile and miRNA expression were different for oxidized and non-oxidized cells.

Conclusions: The present study supports the phenomenon of hypobaric-hypoxia-induced oxidative stress and its role in the impairment of the regenerative capacity of satellite cells derived from the V. Lateralis muscle of young adult female subjects.

Protein Supplementation Does Not Further Increase Latissimus Dorsi Muscle Fiber Hypertrophy after Eight Weeks of Resistance Training in Novice Subjects, but Partially Counteracts the Fast-to-Slow Muscle Fiber Transition

The response to resistance training and protein supplementation in the latissimus dorsi muscle (LDM) has never been investigated. We investigated the effects of resistance training (RT) and protein supplementation on muscle mass, strength, and fiber characteristics of the LDM. Eighteen healthy young subjects were randomly assigned to a progressive eight-week RT program with a normal protein diet (NP) or high protein diet (HP) (NP 0.85 vs. HP 1.8 g of protein·kg⁻¹·day⁻¹). One repetition maximum tests, magnetic resonance imaging for cross-sectional muscle area (CSA), body composition, and single muscle fibers mechanical and phenotype characteristics were measured. RT induced a significant gain in strength (+17%, p < 0.0001), whole muscle CSA (p = 0.024), and single muscle fibers CSA (p < 0.05) of LDM in all subjects. Fiber isometric force increased in proportion to CSA (+22%, p < 0.005) and thus no change in specific tension occurred. A significant transition from 2X to 2A myosin expression was induced by training. The protein supplementation showed no significant effects on all measured outcomes except for a smaller reduction of 2X myosin expression. Our results suggest that in LDM protein supplementation does not further enhance RT-induced muscle fiber hypertrophy nor influence mechanic muscle fiber characteristics but partially counteracts the fast-to-slow fiber shift.

Expression and identification of 10 sarcomeric MyHC isoforms in human skeletal muscles of different embryological origin. Diversity and similarity in mammalian species

In the mammalian genome, among myosin heavy chain (MyHC) isoforms a family can be identified as sarcomeric based on their molecular structure which allows thick filament formation. In this study we aimed to assess the expression of the 10 sarcomeric isoforms in human skeletal muscles, adopting this species as a reference for comparison with all other mammalian species. To this aim, we set up the condition for quantitative Real Time PCR assay to detect and quantify MyHC mRNA expression in a wide variety of human muscles from somitic, presomitic and preotic origin. Specific patterns of expression of the following genes MYH1, MYH2, MYH3, MYH4, MYH6, MYH7, MYH8, MYH13, MYH14/7b and MYH15 were demonstrated in various muscle samples. On the same muscle samples which were analysed for mRNA expression, the corresponding MyHC proteins were studied with SDS PAGE and Western blot. The mRNA-protein comparison allowed the identification of 10 distinct proteins based on the electrophoretic migration rate. Three groups were formed based on the migration rate: fast migrating comprising beta/slow/1, alpha cardiac and fast 2B, slow migrating comprising fast 2X, fast 2A and two developmental isoforms (NEO and EMB), intermediate migrating comprising EO MyHC, slow B (product of MYH15), slow tonic (product of MYH14/7b). Of special interest was the demonstration of a protein band corresponding to 2B-MyHC in laryngeal muscles and the finding that all 10 isoforms are expressed in extraocular muscles. These latter muscles are the unique localization for extraocular, slow B (product of MYH15) and slow tonic (product of MYH14/7b).

Greater loss in muscle mass and function but smaller metabolic alterations in older compared with younger men following 2 wk of bed rest and recovery

This investigation aimed to compare the response of young and older adult men to bed rest (BR) and subsequent rehabilitation (R). Sixteen older (OM, age 55-65 yr) and seven young (YM, age 18-30 yr) men were exposed to a 14-day period of BR followed by 14 days of R. Quadriceps muscle volume (QVOL), force (QF), and explosive power (QP) of leg extensors; single-fiber isometric force (Fo); peak aerobic power (V̇o2peak); gait stride length; and three metabolic parameters, Matsuda index of insulin sensitivity, postprandial lipid curve, and homocysteine plasma level, were measured before and after BR and after R. Following BR, QVOL was smaller in OM (-8.3%) than in YM (-5.7%,P= 0.031); QF (-13.2%,P= 0.001), QP (-12.3%,P= 0.001), and gait stride length (-9.9%,P= 0.002) were smaller only in OM. Fo was significantly smaller in both YM (-32.0%) and OM (-16.4%) without significant differences between groups. V̇o2peakdecreased more in OM (-15.3%) than in YM (-7.6%,P< 0.001). Instead, the Matsuda index fell to a greater extent in YM than in OM (-46.0% vs. -19.8%, respectively,P= 0.003), whereas increases in postprandial lipid curve (+47.2%,P= 0.013) and homocysteine concentration (+26.3%,P= 0.027) were observed only in YM. Importantly, after R, the recovery of several parameters, among them QVOL, QP, and V̇o2peak, was not complete in OM, whereas Fo did not recover in either age group. The results show that the effect of inactivity on muscle mass and function is greater in OM, whereas metabolic alterations are greater in YM. Furthermore, these findings show that the recovery of preinactivity conditions is slower in OM.

Protein supplementation increases postexercise plasma myostatin concentration after 8 weeks of resistance training in young physically active subjects

Myostatin (MSTN) is a negative regulator of muscle growth even if some studies have shown a counterintuitive positive correlation between MSTN and muscle mass (MM). Our aim was to investigate the influence of 2 months of resistance training (RT) and diets with different protein contents on plasma MSTN, interleukin 1 beta (IL-1β), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and insulin-like growth factor 1 (IGF-1). Eighteen healthy volunteers were randomly divided in two groups: high protein (HP) and normal protein (NP) groups. Different protein diet contents were 1.8 and 0.85 g of protein·kg bw(-1)·day(-1) for HP and NP, respectively. Subjects underwent 8 weeks of standardized progressive RT. MSTN, IGF-1, IL-1β, IL-6, and TNF-α were analyzed before and after the first and the last training sessions. Lean body mass, MM, upper-limb muscle area, and strength were measured. Plasma MSTN showed a significant increase (P<.001) after the last training in the HP group compared with NP group and with starting value. IGF-1 plasma concentration showed a positive correlation with MSTN in HP after the last training (r(2)=0.6456; P=.0295). No significant differences were found between NP and HP for IL-1β, IL-6, TNF-α, and strength and MM or area. These findings suggest a "paradoxical" postexercise increase of plasma MSTN after 8 weeks of RT and HP diets. This MSTN elevation correlates positively with IGF-1 plasma level. This double increase of opposite (catabolic/anabolic) mediators could explain the substantial overlapping of MM increases in the two groups.

In vivo and in vitro evidence that intrinsic upper- and lower-limb skeletal muscle function is unaffected by ageing and disuse in oldest-old humans

AIM

To parse out the impact of advanced ageing and disuse on skeletal muscle function, we utilized both in vivo and in vitro techniques to comprehensively assess upper- and lower-limb muscle contractile properties in 8 young (YG; 25 ± 6 years) and 8 oldest-old mobile (OM; 87 ± 5 years) and 8 immobile (OI; 88 ± 4 years) women.

METHODS

In vivo, maximal voluntary contraction (MVC), electrically evoked resting twitch force (RT), and physiological cross-sectional area (PCSA) of the quadriceps and elbow flexors were assessed. Muscle biopsies of the vastus lateralis and biceps brachii facilitated the in vitro assessment of single fibre-specific tension (Po).

RESULTS

In vivo, compared to the young, both the OM and OI exhibited a more pronounced loss of MVC in the lower limb [OM (-60%) and OI (-75%)] than the upper limb (OM = -51%; OI = -47%). Taking into account the reduction in muscle PCSA (OM = -10%; OI = -18%), only evident in the lower limb, by calculating voluntary muscle-specific force, the lower limb of the OI (-40%) was more compromised than the OM (-13%). However, in vivo, RT in both upper and lower limbs (approx. 9.8 N m cm(-2) ) and Po (approx. 123 mN mm(-2) ), assessed in vitro, implies preserved intrinsic contractile function in all muscles of the oldest-old and were well correlated (r = 0.81).

CONCLUSION

These findings suggest that in the oldest-old, neither advanced ageing nor disuse, per se, impacts intrinsic skeletal muscle function, as assessed in vitro. However, in vivo, muscle function is attenuated by age and exacerbated by disuse, implicating factors other than skeletal muscle, such as neuromuscular control, in this diminution of function.

Highly transparent poly(2-ethyl-2-oxazoline)-TiO2 nanocomposite coatings for the conservation of matte painted artworks

A nanocomposite coating based on TiO₂ nanoparticles and poly(2-ethyl-2-oxazoline) is used as consolidant of matte paintings (such as temperas), by exploiting bulk scattering phenomenon to mimic the surface diffusive properties of the painted surface.

Deletion of small ankyrin 1 (sAnk1) isoforms results in structural and functional alterations in aging skeletal muscle fibers

Muscle-specific ankyrins 1 (sAnk1) are a group of small ankyrin 1 isoforms, of which sAnk1.5 is the most abundant. sAnk1 are localized in the sarcoplasmic reticulum (SR) membrane from where they interact with obscurin, a myofibrillar protein. This interaction appears to contribute to stabilize the SR close to the myofibrils. Here we report the structural and functional characterization of skeletal muscles from sAnk1 knockout mice (KO). Deletion of sAnk1 did not change the expression and localization of SR proteins in 4- to 6-mo-old sAnk1 KO mice. Structurally, the main modification observed in skeletal muscles of adult sAnk1 KO mice (4-6 mo of age) was the reduction of SR volume at the sarcomere A band level. With increasing age (at 12-15 mo of age) extensor digitorum longus (EDL) skeletal muscles of sAnk1 KO mice develop prematurely large tubular aggregates, whereas diaphragm undergoes significant structural damage. Parallel functional studies revealed specific changes in the contractile performance of muscles from sAnk1 KO mice and a reduced exercise tolerance in an endurance test on treadmill compared with control mice. Moreover, reduced Qγ charge and L-type Ca(2+) current, which are indexes of affected excitation-contraction coupling, were observed in diaphragm fibers from 12- to 15-mo-old mice, but not in other skeletal muscles from sAnk1 KO mice. Altogether, these findings show that the ablation of sAnk1, by altering the organization of the SR, renders skeletal muscles susceptible to undergo structural and functional alterations more evident with age, and point to an important contribution of sAnk1 to the maintenance of the longitudinal SR architecture.

A mutation in the CASQ1 gene causes a vacuolar myopathy with accumulation of sarcoplasmic reticulum protein aggregates

A missense mutation in the calsequestrin-1 gene (CASQ1) was found in a group of patients with a myopathy characterized by weakness, fatigue, and the presence of large vacuoles containing characteristic inclusions resulting from the aggregation of sarcoplasmic reticulum (SR) proteins. The mutation affects a conserved aspartic acid in position 244 (p.Asp244Gly) located in one of the high-affinity Ca(2+) -binding sites of CASQ1 and alters the kinetics of Ca(2+) release in muscle fibers. Expression of the mutated CASQ1 protein in COS-7 cells showed a markedly reduced ability in forming elongated polymers, whereas both in cultured myotubes and in in vivo mouse fibers induced the formation of electron-dense SR vacuoles containing aggregates of the mutant CASQ1 protein that resemble those observed in muscle biopsies of patients. Altogether, these results support the view that a single missense mutation in the CASQ1 gene causes the formation of abnormal SR vacuoles containing aggregates of CASQ1, and other SR proteins, results in altered Ca(2+) release in skeletal muscle fibers, and, hence, is responsible for the clinical phenotype observed in these patients.

Effect of hyperbaric oxygenation and gemcitabine on apoptosis of pancreatic ductal tumor cells in vitro

BACKGROUND

Gemcitabine is first-line therapy for advanced pancreatic ductal adenocarcinoma (PDAC) with a poor survival and response rate. Hyperbaric oxygenation (HBO) enhances delivery of oxygen to hypoxic tumor cells and increases their susceptibility to cytotoxic effects of chemotherapy. We hypothesized that the anticancer activity of gemcitabine (GEM) may be enhanced if tumor cells are placed in an oxygen-rich environment. The present study evaluated the effects of gemcitabine, HBO and their combination on apoptosis of tumor cells.

MATERIALS AND METHODS

PANC-1 and AsPc-1 PDAC tumor cell lines were used. Cultured tumor cells were treated with GEM at its growth-inhibitory concentration (IC50) and HBO at 2.5 ATA for 90 min or a combination of both (HBO then GEM and GEM then HBO). Twenty-four hours later, apoptotic cells in each group were analyzed and the apoptotic index (AI) was calculated.

RESULTS

PANC-1 cell line: HBO alone had no effect on AI: 6.5 ± 0.1 vs. 5.9 ± 0.1. HBO before and after gemcitabine did not further increase AI: 8.2 ± 0.1 (HBO-GEM), 8.5 ± 0.1 (GEM-HBO) vs. 8.1 ± 0.1 (GEM). The combination of HBO and gemcitabine significantly increased AI: 10.7 ± 0.02 (p<0.001 vs. all groups). AsPc-1 cell line: HBO-alone had no effect on AI: 5.9 ± 0.1 vs. 5.9 ± 0.1. HBO before and after gemcitabine did not further increase AI: 8.2 ± 0.1 (HBO-GEM), 8.4 ± 0.1 (GEM-HBO) vs. 8.0 ± 0.1 (GEM). The combination of HBO and gemcitabine significantly increased AI: 9.7 ± 0.1 (p<0.001 vs. all groups).

CONCLUSION

HBO-alone, whether administered before and after gemcitabine has no effect on apoptosis of PDAC cells in vitro. HBO significantly enhanced gemcitabine-induced apoptosis when administered during gemcitabine. Our findings suggest that the time window would be critical for using HBO as adjuvant to chemotherapy.

Mitochondrial Ca2+-handling in fast skeletal muscle fibers from wild type and calsequestrin-null mice

Mitochondrial calcium handling and its relation with calcium released from sarcoplasmic reticulum (SR) in muscle tissue are subject of lively debate. In this study we aimed to clarify how the SR determines mitochondrial calcium handling using dCASQ-null mice which lack both isoforms of the major Ca²⁺-binding protein inside SR, calsequestrin. Mitochondrial free Ca²⁺-concentration ([Ca²⁺]_mito) was determined by means of a genetically targeted ratiometric FRET-based probe. Electron microscopy revealed a highly significant increase in intermyofibrillar mitochondria (+55%) and augmented coupling (+12%) between Ca²⁺ release units of the SR and mitochondria in dCASQ-null vs. WT fibers. Significant differences in the baseline [Ca²⁺]_mito were observed between quiescent WT and dCASQ-null fibers, but not in the resting cytosolic Ca²⁺ concentration. The rise in [Ca²⁺]_mito during electrical stimulation occurred in 20−30 ms, while the decline during and after stimulation was governed by 4 rate constants of approximately 40, 1.6, 0.2 and 0.03 s⁻¹. Accordingly, frequency-dependent increase in [Ca²⁺]_mito occurred during sustained contractions. In dCASQ-null fibers the increases in [Ca²⁺]_mito were less pronounced than in WT fibers and even lower when extracellular calcium was removed. The amplitude and duration of [Ca²⁺]_mito transients were increased by inhibition of mitochondrial Na⁺/Ca²⁺ exchanger (mNCX). These results provide direct evidence for fast Ca²⁺ accumulation inside the mitochondria, involvement of the mNCX in mitochondrial Ca²⁺-handling and a dependence of mitochondrial Ca²⁺-handling on intracellular (SR) and external Ca²⁺ stores in fast skeletal muscle fibers. dCASQ-null mice represent a model for malignant hyperthermia. The differences in structure and in mitochondrial function observed relative to WT may represent compensatory mechanisms for the disease-related reduction of calcium storage capacity of the SR and/or SR Ca²⁺-leakage.

S1P2 receptor promotes mouse skeletal muscle regeneration

Sphingosine 1-phosphate is a bioactive lipid that modulates skeletal muscle growth through its interaction with specific receptors localized in the cell membrane of muscle fibers and satellite cells. This study analyzes the role of S1P2 receptor during in vivo regeneration of soleus muscle in two models of S1P2 deficiency: the S1P2-null mouse and wild-type mice systemically treated with the S1P2 receptor antagonist JTE-013. To stimulate regeneration, muscle degeneration was induced by injecting into soleus muscle the myotoxic drug notexin. Both ablation of S1P2 receptor and its functional inactivation delayed regeneration of soleus muscle. The exogenous supplementation of S1P or its removal, by a specific antibody, two conditions known to stimulate or inhibit, respectively, soleus muscle regeneration, were without effects when the S1P2 receptor was absent or inactive. The delayed regeneration was associated with a lower level of myogenin, a muscle differentiation marker, and reduced phosphorylation of Akt, a key marker of muscle growth. Consistently, silencing of S1P2 receptor abrogated the pro-myogenic action of S1P in satellite cells, paralleled by low levels of the myogenic transcription factor myogenin. The study indicates that S1P2 receptor plays a key role in the early phases of muscle regeneration by sustaining differentiation and growth of new-forming myofibers.

Inflammation in muscular dystrophy and the beneficial effects of non-steroidal anti-inflammatory drugs

INTRODUCTION

Glucocorticoids are the only drugs available for the treatment of Duchenne muscular dystrophy (DMD), but it is unclear whether their efficacy is dependent on their anti-inflammatory activity.

METHODS

To address this issue, mdx mice were treated daily with methylprednisolone and non-steroidal anti-inflammatory drugs (NSAIDs: aspirin, ibuprofen, parecoxib).

RESULTS

NSAID treatment was effective in ameliorating muscle morphology and reducing macrophage infiltration and necrosis. The percentage of regenerating myofibers was not modified by the treatments. The drugs were effective in reducing COX-2 expression and inflammatory cytokines, but they did not affect utrophin levels. The effects of the treatments on contractile performance were analyzed. Isometric tension did not differ in treated and untreated muscle, but the resistance to fatigue was decreased by treatment with methylprednisolone and aspirin.

CONCLUSIONS

NSAIDs have a beneficial effect on mdx muscle morphology, pointing to a crucial role of inflammation in the progression of DMD.

Degradation of nitrocellulose-based paint by Desulfovibrio desulfuricans ATCC 13541

Nitrocellulose is one of the most commonly used compounds in ammunition and paint industries and its recalcitrance to degradation has a negative impact on human health and the environment. In this study the capability of Desulfovibrio desulfuricans ATCC 13541 to degrade nitrocellulose as binder in paint was assayed for the first time. Nitrocellulose-based paint degradation was followed by monitoring the variation in nitrate, nitrite and ammonium content in the culture medium using Ultraviolet-Visible spectroscopy. At the same time cell counts and ATP assay were performed to estimate bacterial density and activity in all samples. Infrared spectroscopy and colorimetric measurements of paint samples were performed to assess chemical and colour changes due to the microbial action. Microscope observations of nitrocellulose-based paint samples demonstrated the capability of the bacterium to adhere to the paint surface and change the paint adhesive characteristics. Finally, preliminary studies of nitrocellulose degradation pathway were conducted by assaying nitrate- and nitrite reductases activity in D. desulfuricans grown in presence or in absence of paint. We found that D. desulfuricans ATCC 13541 is able to transform nitrocellulose as paint binder and we hypothesised ammonification as degradation pathway. The results suggest that D. desulfuricans ATCC 13541 is a good candidate as a nitrocellulose-degrading bacterium.

Nutrition and acne: therapeutic potential of ketogenic diets

The influence of nutrition on skin health is a growing research area but the findings of various studies on the effect of diet on the development of acne have often been contradictory. The general opinion among researchers has oscillated between two different, opposing positions: that diet either is or is not a key factor for acne development. This review examines the evidence supporting an influence of various dietary components on the development of acne particularly focusing on the role played by carbohydrates. The physiological and biochemical effects of the ketogenic diet are examined from this perspective and mechanisms will be proposed via which this type of diet could have a role in the treatment of acne.