The Influence of Plasma Treatment on the Corrosion and Biocompatibility of Magnesium

In our study, plasma surface modification was employed to tailor the surface properties of magnesium in terms of surface chemistry, topography, and wettability. For two sets of samples, the plasma treatment involved two steps using two different gases (hydrogen and oxygen), while one set of samples was treated with one step only using oxygen. X-ray photoelectron spectroscopy (XPS) was applied to determine the surface composition, oxidation state of the elements, and the thickness of the surface oxide layer on the Mg samples after different plasma treatments. The surface morphology was characterised using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The wettability was analysed by measuring the static water-contact angles and the corrosion was evaluated using potentiodynamic measurements. The interaction of the live cells with the differently modified Mg surfaces was evaluated in terms of biocompatibility using MG-63 cells (human bone osteosarcoma cells). We have shown that a plasma surface treatment significantly decreased the carbon content and the formation of a 15-20-nm-thick MgO layer was observed. This improves the corrosion resistance, while the biocompatibility was retained, compared to the untreated Mg. A plasma surface treatment is therefore an important step in the development of novel surfaces with improved corrosion resistance for magnesium in biomedical applications.

The effect of high intensity combined training on functional capacity, muscle strength, body composition, agility and dynamic balance in patients with coronary artery disease

Funding Acknowledgements

Type of funding sources: None.

Introduction

There is still controversy regarding the exercise characteristics that are more effective for improving peak oxygen uptake (VO2 peak), cardiac and metabolic function. High- intensity interval exercise training (HIIT) has been shown to elicit comparable and/or superior performance on endurance capacity (EC), ventricular function (VF) and quality of life. By other side, there is robust evidence that combined endurance and strength training is significantly more effective than endurance training only for improving EC, muscle mass and muscle strength.

There is no enough information if the combination of HIIT with high strength training (HST) could enhance the physical conditions of these patients.

Purpose

The purpose of our study was to analyze the combination of HIIT + HST and its effect on physical performance compared to different types of combined training: HIIT and MCT with low load resistance training (RT) and HIIT or MCT only.

Methods

We evaluated 140 male patients (p) with CAD documented by angiographic studies, clinically stables with medical treatment and sinus rhythm.

All of them performed a stress testing in treadmill without handrail support using a ramp protocol until maximal effort. VO2 peak (ml/kg/min) was measured indirectly through ACSM formula. We used YMCA´s method of estimating body fat with measurement of skinfolds in four sites (BF %), 30-second chair stand test (CST), 8-foot up and go test (FUGT), six-minute walk test (T6min) and one maximum repetition for quadriceps extension (1RMq) .Training intervention: p were randomly allocated to HIIT + RT (n=30), MCT + RT (n=30), HIIT (n=30), MCT (n=30) and HIIT + HST (n=20) during 3 month period of training.

HIIT: 4 x 4 (85-95% peak heart rate) and 60-70% during active breaks. (36 min)

MCT: 70-75% peak heart rate.(36 min)

RT: 40-50% 1RM for lower body with 12-15 repetitions in 2 sets

HST: ≥ 70% 1RM for lower body with low number of repetitions.

Statistical analysis: all data were analyzed using IBM SPSS V.24. Comparisons were performed by following one-way ANOVA(parametric distribution) with post-hoc Tuckey or Kruskal-Wallis(non parametric distribution). The level of statistical significance was P< 0.05.

Results

Analyzing values pretraining (PRE) vs. postraining (POST), VO2 peak increased significantly by 27,52% for HIIT + HST P< 0,03 vs. HIIT + RT- MCT + RT and MCT. A positive effect in HIIT + HST with FUGT P< 0,001 and CST P< 0,005 between group changes and favourable observations in relation to 1RMq (PRE 60,00 ± 9,07 vs. POST 73,00 ± 9,86) and %BF(PRE 26,60 ± 3,21 vs. POST 24,80 ± 3,72) compared to MCT and HIIT P < 0,05. We didn´t find statistical significant differences with both modalities of combined training (low workloads) and HIIT for T6min.

Conclusions

High intensity combined training (HIIT + HST) had an additional effect related to others aerobic and resistance exercises attributed to neuromuscular adaptations, increased power and muscle strength.

The Oleofobization of Paper via Plasma Treatment

Cellulose is a promising biomass material suitable for high volume applications. Its potential lies in sustainability, which is becoming one of the leading trends in industry. However, there are certain drawbacks of cellulose materials which limit their use, especially their high wettability and low barrier properties, which can be overcome by applying thin coatings. Plasma technologies present a high potential for deposition of thin environmentally friendly and recyclable coatings. In this paper, two different plasma reactors were used for coating two types of cellulose-based substrates with hexamethyldisiloxane (HMDSO). The changes in surface characteristics were measured by atomic force microscopy (AFM), scanning electron microscopy (SEM), surface free energy and contact angles measurements, X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). Successful oleofobization was observed for an industrial scale reactor where pure HMDSO was used in the absence of oxygen.

Use of Plasma Technologies for Antibacterial Surface Properties of Metals

Bacterial infections of medical devices present severe problems connected with long-term antibiotic treatment, implant failure, and high hospital costs. Therefore, there are enormous demands for innovative techniques which would improve the surface properties of implantable materials. Plasma technologies present one of the compelling ways to improve metal's antibacterial activity; plasma treatment can significantly alter metal surfaces' physicochemical properties, such as surface chemistry, roughness, wettability, surface charge, and crystallinity, which all play an important role in the biological response of medical materials. Herein, the most common plasma treatment techniques like plasma spraying, plasma immersion ion implantation, plasma vapor deposition, and plasma electrolytic oxidation as well as novel approaches based on gaseous plasma treatment of surfaces are gathered and presented. The latest results of different surface modification approaches and their influence on metals' antibacterial surface properties are presented and critically discussed. The mechanisms involved in bactericidal effects of plasma-treated surfaces are discussed and novel results of surface modification of metal materials by highly reactive oxygen plasma are presented.

Affinity of Serum Albumin and Fibrinogen to Cellulose, Its Hydrophobic Derivatives and Blends

This work describes the preparation of spin-coated thin polymer films composed of cellulose (CE), ethyl cellulose (EC), and cellulose acetate (CA) in the form of bi- or mono-component coatings on sensors of a quartz crystal microbalance with dissipation monitoring (QCM-D). Depending on the composition and derivative, hydrophilicity can be varied resulting in materials with different surface properties. The surfaces of mono- and bi-component films were also analyzed by atomic force microscopy (AFM) and large differences in the morphologies were found comprising nano- to micrometer sized pores. Extended protein adsorption studies were performed by a QCM-D with 0.1 and 10 mg mL⁻¹ bovine serum albumin (BSA) and 0.1 and 1 mg mL⁻¹ fibrinogen from bovine plasma in phosphate buffered saline. Analysis of the mass of bound proteins was conducted by applying the Voigt model and a comparison was made with the Sauerbrey wet mass of the proteins for all films. The amount of deposited proteins could be influenced by the composition of the films. It is proposed that the observed effects can be exploited in biomaterial science and that they can be used to extent the applicability of bio-based polymer thin films composed of commercial cellulose derivatives.

Comparison of SF₆ and CF₄ Plasma Treatment for Surface Hydrophobization of PET Polymer

The fluorination of the polymer polyethylene terephthalate in plasma created from SF₆ or CF₄ gas at various pressures was investigated. The surface was analysed by X-ray photoelectron spectroscopy and water contact angle measurements, whereas the plasma was characterized by optical emission spectroscopy. The extent of the polymer surface fluorination was dependent on the pressure. Up to a threshold pressure, the amount of fluorine on the polymer surface and the surface hydrophobicity were similar, which was explained by the full dissociation of the SF₆ and CF₄ gases, leading to high concentrations of fluorine radicals in the plasma and thus causing the saturation of the polymer surface with fluorine functional groups. Above the threshold pressure, the amount of fluorine on the polymer surface significantly decreased, whereas the oxygen concentration increased, leading to the formation of the hydrophilic surface. This effect, which was more pronounced for the SF₆ plasma, was explained by the electronegativity of both gases.

Influence of various sterilization procedures on TiO2 nanotubes used for biomedical devices

Sterilization is the final surface treatment procedure of all implantable devices and is one of the key factors which have to be considered before implementation. Since different sterilization procedures for all implantable devices influence mechanical properties as well as biological response, the influence of different sterilization techniques on titanium nanotubes was studied. Commonly used sterilization techniques such as autoclaving, ultra-violet light sterilization, hydrogen peroxide plasma sterilization as well as the not so frequently used gaseous oxygen plasma sterilization were used. Three different nanotube diameters; 15 nm, 50 nm and 100 nm were employed to study the effects of various sterilization techniques. It was observed that autoclave sterilization resulted in destruction of nanotubular features on all three studied nanotube diameters, while UV-light and both kinds of plasma sterilization did not cause any significant morphological changes on the surfaces. Differences between the sterilization techniques employed influenced cytocompatibility, especially in the case of nanotubes with 100 nm diameter.

The cholestyramine-induced decrease of PYY postprandial response is negatively correlated with fat mass in obese women

Obese patients have decreased fasting and postprandial levels of peptide YY (PYY), an anorexigenic peptide produced by the L cells of the gastrointestinal mucosa. Fatty nutrients are the most powerful stimulus for PYY release. Cholestyramine, an anion exchanger which adsorbs bile salts, reduces digestion of lipids. The aim of the present study was to investigate the effects of cholestyramine or placebo on PYY secretion in obese women administered a high-fat meal [n=8; age: 30.9±2.7 years; BMI: 47.3±3.3 kg/m2]. Postprandial PYY levels in obese women given placebo significantly increased in plasma at 30, 60, 90, and 120 min after meal ingestion. Cholestyramine administration significantly reduced postprandial PYY response at 15, 30, and 60 min. Percent fat mass (FM%) was negatively correlated with the percent increment of plasma PYY concentrations induced by meal administration at 30 min; conversely, there was a positive correlation between FM% and the percent decrement of plasma PYY concentrations induced by cholestyramine at the same time interval. These correlations failed to reach statistical significance when related to BMI. This study implies that in the obese state the altered PYY response to food consumption is a consequence of a dysfunction of L cells, which become less sensitive to the positive feedback effect of lipids.

Prediction of resting energy expenditure in severely obese Italian males

The objectives of the present study were to develop and cross-validate new equations for predicting resting energy expenditure (PREE) in severely obese Italian males, and to compare their accuracy with those of the Harris-Benedict, WHO/ FAO/UNU, Huang, Owen, Mifflin, Livingston, Nelson, Bernstein, and Cunnimgham equations in order to predict resting energy expenditure (REE), using the Bland-Altman method. One hundred and sixty-four severely obese males [mean body mass index (BMI): 45.4 kg/m2; 50.2% fat mass), aged 20 to 65 yr participated in this study. REE was measured by indirect calorimetry and body composition by bioelectrical analysis. Equations were derived by stepwise multiple regression analysis using a calibration group and tested against the validation group. Two new specific equations, based on anthropometric [REE=Weight x 0.048 + Height x 4.655 - age x 0.020 - 3.605 (R2=0.68, SE=1.14 MJ/d)] or body composition parameters [REE=fat free mass (FFM) x 0.081 + fat mass (FM) x 0.049 - age x 0.019 - 2.194 (R2=0.65, SE=1.15 MJ/d)], were generated. Mean PREE were not different from the mean measured REE (MREE) (<1%, p<0.001), REE being predicted accurately (95-105% of MREE) in 66 and 62% of subjects, respectively. The Harris-Benedict, WHO/FAO/UNU, Huang and Owen equations showed mean differences lower than 5% and PREE was accurate in less than 30% of subjects. The Mifflin, Livingston, and Nelson equations showed a mean PREE underestimation >7% (p<0.001) and PREE was accurate in less than 25% of subjects. The Bernstein and Cunningham equations showed a greater PREE underestimation (>22%, p<0.001) in more than 85% of subjects. The new prediction equations allow an accurate estimation of REE in groups of severely obese males and result in lower mean differences and lower limits of agreement between PREE and MREE than the commonly used equations.

Postural instability of extremely obese individuals improves after a body weight reduction program entailing specific balance training

The purposes of this study were to compare postural stability between obese and lean subjects and to investigate the effect of a 3-week body weight reduction (BWR) program entailing specific balance training on postural stability of extremely obese patients. Time of balance maintenance and mean error on the medial-lateral direction at the trunk and lower limb level were assessed during a single limb stance on a movable platform in 19 non-obese and in 20 extremely obese individuals (age range: 20-40 yr). Time of balance maintenance was shorter (obese: 21.1+/-7.7 vs lean: 27.3+/-3.1 sec) and medial-lateral sway of the trunk was larger in obese (5.4+/-3.2 degrees) than in lean (3.2+/-1.1 degrees) subjects (p<0.05). Two subgroups of obese subjects were also tested after a BWR program (energy-restricted diet, moderate physical exercise, nutritional education and psychological counselling) combined with or without 6 sessions of specific balance training on a movable platform. BWR plus specific balance training enhanced time of balance maintenance (pre: 23.8+/-7.2 vs post: 30.0+/-0.0 sec) and reduced the trunk sway (5.2+/-2.8 degrees vs 2.6+/-0.9 degrees ) more than BWR alone (p<0.05). The present findings indicate that extremely obese individuals have inadequate postural stability (compared to their lean counterparts) that could however be improved by few sessions of specific balance training incorporated into a multidisciplinary BWR program. It was concluded that balance improvement is an important goal of rehabilitation, that would probably reduce the propensity of overweight individuals to fall while performing everyday activities.

Ghrelin secretion in severely obese subjects before and after a 3-week integrated body mass reduction program

Ghrelin, the endogenous ligand of GH-secretagogue receptors, has been implicated in the regulation of feeding behavior and energy balance. Aim of the study was to investigate ghrelin levels in fasting conditions and after a standard meal test in obese subjects before and after a 3-week integrated body weight reduction (BWR) program (consisting of energy-restricted diet, exercise training, psychological counselling and nutritional education). Weight, height, fat mass, fat free mass (by impedentiometry), circulating ghrelin, insulin and leptin levels were evaluated in 10 obese subjects (3 male, 7 female; mean age: 35 +/- 9.3 yr; body mass index BMI: 45.2 +/- 10.6 kg/m2) before and after weight reduction. At baseline, obese subjects showed significantly lower ghrelin levels than controls, which were negatively correlated with BMI, weight, insulin and leptin levels. Fasting ghrelin levels were not modified by standard meal test in obese subjects (from 110.8 +/- 69.7 to 91.8 +/- 70.2 pmol/l p=ns), while a significant reduction was observed in controls (from 352.4 +/- 176.7 to 199.0 +/- 105.2 pmol/l; p<0.01). After a 3-week integrated BWR program obese subjects significantly reduced weight, BMI and leptin levels, while no significant changes were found both in fasting ghrelin and in ghrelin response after the meal. In conclusion, 5% weight loss obtained after a short-term period of integrated BWR program is not sufficient to normalize fasting ghrelin levels nor to restore the normal ghrelin suppression after a meal in severely obese subjects.

Effects of non-specific vs individualized exercise training protocols on aerobic, anaerobic and strength performance in severely obese subjects during a short-term body mass reduction program

The purpose of the present study was to compare aerobic, anaerobic and strength performance changes induced by two short-term (3-week) body mass reduction programs based on the same low-calory diet (1200-1500 kcal/day), nutritional education and psychological counseling, but entailing different exercise training protocols. An individualized, low-volume and moderate-intensity exercise training (IET) was contrasted with a non-specific, high-volume, low-intensity exercise training (NET). Thirty obese in-patients (12 males, 18 females; mean age +/- SD: 33.9 +/- 9.4 yr, range: 19-51yr; mean BMI: 40.5 +/- 3.8 kg/m2, range: 35.3-51.4 kg/m2) were randomly divided in two gender-matched groups of 15 subjects each undergoing a different exercise training protocol. Maximum oxygen uptake (VO2max) determined with a submaximal indirect test on a bicycle ergometer, lower limb maximum power output (W(max)) determined with the jumping method, global motor capabilities determined by analysis of locomotor pattern during a short (8 m) running, maximum strength (1-RM) of upper and lower limb muscle groups determined with isotonic machines were tested before and after the program. Adherence to an individual exercise activity and maintenance of body weight (bw) loss were evaluated with a telephonic interview 6 months after the completion of the program. In both groups a significant (p < 0.001) and comparable weight loss was observed (IET: -4.27%; NET: -4.17%). In both groups VO2max and W(max) increased significantly (p < 0.05-0.001) when expressed relatively to body mass, while in absolute terms they were significantly (p < 0.001) improved only in IET group. 1-RM in all tested muscle groups was significantly increased in both IET and NET subjects (p < 0.001-0.01), but improvements were significantly greater in IET as compared with NET (p < 0.05-0.001). The analysis of locomotor pattern during the short running indicated that IET subjects significantly improved their global motor capabilities (p < 0.05-0.001), while no change was observed in NET group. After 6 months, IET subjects reported a level of spontaneously chosen physical activity significantly higher (p < 0.05) than NET subjects, displaying a trend of further decrease in bw. It was concluded that, although no difference in bw loss was appreciated between the two studied groups and significant improvements were found also in subjects performing NET protocol, the IET protocol offers better overall results in terms of muscle performance and physical fitness, with a possibly stronger motivation to subsequent exercise activity.

Effects of a 3-week integrated body weight reduction program on leptin levels and body composition in severe obese subjects

The effects of short-term (3 weeks) integrated body weight reduction (BWR) program (including energy-restricted diet, aerobic and strength exercise (5 days/week), nutritional education and psychological counseling) on plasma leptin levels and body composition were investigated in 54 morbidly obese patients (38 females/16 males; mean BMI +/- SE: 41.8 +/- 0.1 kg/m2, range 35-58 kg/m2; mean age: 29.8 +/- 1.0 yr, age range: 18-46 yr). The BWR program induced a significant (p < 0.001) weight loss (BMI reduction: -4.8%) and a significant modification in body composition, consisting in a fat mass (FM) decrease (-7.0 +/- 0.4%, p < 0.001) with a concomitant fat-free (FFM) mass increase (1.8 +/- 0.3%, p < 0.001). On average, plasma leptin levels decreased significantly both in males (from 19.4 +/- 2.6 ng/ml to 11.6 +/- 1.3 ng/ml, p < 0.001) and in females (from 41.1 +/- 3.6 ng/ml to 29.9 +/- 3.0 ng/ml, p < 0.001). Both before and after weight loss, leptin levels were positively correlated (p < 0.001) with BMI and percent fat mass (FM) values. Weight changes after the BWR program were negatively correlated with baseline leptin concentrations both in absolute terms and expressed per unit FM. In conclusion, a short-term diet plus aerobic/strength training effectively induces body composition changes and reduces plasma leptin levels. Body FM reduction appears to be not the unique determinant of leptin levels regulation and the degree of leptin over-expression may negatively affect weight loss in morbidly obese patients.

Effects of 12 months rhGH treatment on bone and collagen turnover in children with constitutional growth delay

Serum bone Gla protein (BGP), marker of osteoblast function, serum carboxyterminal cross-linked telopeptide of type I collagen (ICTP) and urinary free deoxypyridinoline (DPD), markers of bone resorption, and the aminoterminal propeptide of type III procollagen (PIIINP), marker of type III collagen turnover, were determined in eight prepubertal children (8 males, age range 7-9.6 yr, Tanner stage I) with constitutional growth delay (CGD), before and after 6-12 months of treatment with rhGH (Saizen, Serono, 0.6 IU/kg/week, s.c.). Serum BGP (mean+/-SD: 15.4+/-1.7 ng/ml), ICTP (9.4+/-1.6 ng/ml) and urinary DPD/creatinine (11.3+/-1.7 nmol/mmol) levels were significantly lower (p<0.02, p<0.0001 and p<0.02, respectively) in children with CGD than in healthy age-matched controls (BGP: 18.9+/-3.6 ng/ml, ICTP: 14.3+/-2.6 ng/ml, DPD: 20.7+/-10.0 nmol/mmol), while PIIINP levels of patients were similar to those recorded in controls (6.3+/-0.7 vs 6.7+/-2.3 ng/ml, respectively). Serum BGP, urinary free DPD/creatinine and PIIINP levels significantly increased after 6 (BGP: 20.9+/-2.1 ng/ml, p<0.0001; DPD/creatinine: 16.3+/-3.6 nmol/mmol, p<0.001; PIIINP: 8.1+/-1.6 ng/ml, p<0.005) and 12 months (BGP: 19.2+/-2.0 ng/ml, p<0.0001; DPD/creatinine: 19.7+/-5.1 nmol/mmol, p<0.001; PIIINP: 8.8+/-1.9 ng/ml, p<0.002) of GH treatment. Serum ICTP levels did not significantly change after 6 months (10.6+/-2.1 ng/ml), while a significant increase (p<0.002) was evident after 12 months of therapy (13.6+/-1.3 ng/ml). Our study shows that BGP, ICTP and DPD/creatinine levels are significantly reduced in children with CGD, thus indicating the presence of low bone turnover in this form of short stature. Since GH treatment is able to reactivate bone remodeling and increase collagen synthesis, it is tempting to speculate that a partial GH-IGF-I defect (i.e. locally at bone level) might be one of the factors involved in determining the biochemical alterations of bone metabolism found in this clinical condition.