Rapid Mineralization of Electrospun Scaffolds for Bone Tissue Engineering

We investigated different techniques to enhance calcium phosphate mineral precipitation onto electrospun poly(_L-lactide) (PLLA) scaffolds when incubated in concentrated simulated body fluid (SBF), 10×SBF. The techniques included the use of vacuum, pre-treatment with 0.1 M NaOH and electrospinning gelatin/PLLA blends as means to increase overall mineral precipitation and distribution throughout the scaffolds. Mineral precipitation was evaluated using environmental scanning electron microscopy, energy dispersive spectroscopy mapping and the determination of the mineral weight percents. In addition we evaluated the effect of the techniques on mechanical properties, cellular attachment and cellular proliferation on scaffolds. Two treatments, pre-treatment with NaOH and incorporation of 10% gelatin into PLLA solution, both in combination with vacuum, resulted in significantly higher degrees of mineralization (16.55 and 15.14%, respectively) and better mineral distribution on surfaces and through the cross-sections after 2 h of exposure to 10×SBF. While both scaffold groups supported cell attachment and proliferation, 10% gelatin/PLLA scaffolds had significantly higher yield stress (1.73 vs 0.56 MPa) and elastic modulus (107 vs 44 MPa) than NaOH-pre-treated scaffolds.     

In Vitro Biocompatibility of New PVA-Based Hydrogels as Vitreous Body Substitutes

In order to synthesize injectable hydrogels suitable as vitreous body substitutes, a new method based on the use of trisodium trimetaphosphate (STMP) to cross-link PVA was recently proposed. Hydrogels with different molar ratios between STMP and PVA were realised. The aim of the present study was the evaluation of the biocompatibility of the different STMP/PVA hydrogels synthesised by analysing the effects of their in vitro interaction with cultures of mouse fibroblasts NIH3T3, primary human microvascular endothelial cells adult (HMVECad) and human lens cells. Cytotoxicity of hydrogels was first evaluated by analysing cell density and proliferation. Morphological and morphometric analysis of cell in contact with hydrogels was then performed using light microscopy and scanning electron microscopy, respectively. Moreover, cell adhesion and growth onto the hydrogels surface was evaluated and correlated to the amount of adsorbed proteins. At last, the biocompatibility of the sheared STMP/PVA 1:8 hydrogel was tested. The in vitro data of all the STMP/PVA hydrogels demonstrated their good biocompatibility, and indicated that the 1:8 sample was the most promising as vitreous body substitute.     

Rho GTPase protein expression and activation in murine monocytes/macrophages are not modulated by model biomaterial surfaces in serum-containing in vitro cultures

The Rho GTPase cellular signaling cascade was investigated in pro-monocyte and (monocyte-)macrophage cells by examining GTPase expression and activation in serum-containing cultures on model biomaterials. Abundance of Rho GDI and the Rho GTPase proteins RhoA, Cdc42 and Rac1 was determined in cells grown on tissue-culture polystyrene, polystyrene, poly-L-lactide and Teflon^® AF surfaces. Protein expression was compared based on cell maturity (pro-monocyte to monocyte to macrophage lineages) and by model surface chemistry: Rho proteins were present in the majority of macrophage cells tested on model surfaces suggesting that a pool of Rho proteins is readily available for signaling events in response to numerous activating cues, including biomaterials surface encounter. Rho GTPase activation profiles in these cell lines indicate active Cdc42 and Rho proteins in RAW 264.7, Rac1 and Rho in J774A.1, and Cdc42 and Rac1 in IC-21 cell lines, respectively. Collectively, these proteins are known to play critical roles in all actin-based cytoskeletal rearrangement necessary for cell adhesion, spreading and motility, and remain important to establishing cellular responses required for foreign body reactions in vivo. Differences in Rho GTPase protein expression levels based on cell sourcing (primary versus secondary-derived cell source), or as a function of surface chemistry were insignificant. Rho GTPase expression profiles varied between pro-monocytic non-adherent precursor cells and mature adherent monocyte/macrophage cells. The active GTP-bound forms of the Rho GTPase proteins were detected from monocyte-macrophage cell lines RAW 264.7 and J774A.1 on all polymer surfaces, suggesting that while these proteins are central to cell adhesive behavior, differences in surface chemistry are insufficient to differentially regulate GTPase activation in these cell types. Active Cdc42 was detected from cells cultured on the more-polar tissue-culture polystyrene and poly-L-lactide surfaces after several days, but absent from those grown on apolar polystyrene and Teflon^® AF, indicating some surface influence on this GTPase in serum-containing cultures.     

Biomimetic Fabrication of Hydroxyapatite–Polysaccharide–Formate Dehydrogenase Composite Capsules for Efficient CO2 Conversion

In this study, a novel kind of hydroxyapatite–polysaccharide capsules was prepared through a bio-inspired process in simulated body fluid for efficient encapsulation of formate dehydrogenase. In this process, a thin alginate/chitosan film formed immediately around the capsules coupled with in situ precipitation of hydroxyapatite when alginate HPO₄ ^2?-stock solution droplets were added into chitosan Ca²⁺-stock solution. The biomineralization of hydroxyapatite was mimicked by the counter-diffusion system in which calcium ions and phosphate ions migrated into the alginate/chitosan film from opposite directions. Formation of capsule was confirmed by Zoom Stereo Microscopy, the surface morphology of the capsule was characterized by SEM, the surface element composition of capsules was analyzed by EDX and the pore size distribution of capsule shell was determined by BET. As compared to the free formate dehydrogenase, hydroxyapatite–polysaccharide–formate dehydrogenase composite capsules exhibited significantly higher activity and storage stability in a broader temperature and pH range when converting CO₂ to formic acid.     

The role of vitamin D in improving physical performance in the elderly

There is an ongoing debate over the role of serum 25(OH) vitamin D [25(OH)D] levels in maintaining or improving physical performance and muscle strength. Much of the controversy is because of the variability between studies in participants' characteristics, baseline serum 25(OH)D levels, and baseline physical functioning. The aim of this ancillary study conducted within a randomized controlled clinical trial was to investigate whether supplementation with 400 or 2000 IU vitamin D₃ daily for 6 months would improve measures of physical performance and muscle strength in a community‐dwelling elderly population aged 65 to 95 years. Those with the slowest gait speed improved their ability to do chair‐stand tests after vitamin D supplementation. This finding remained significant after controlling for potential confounding variables. There was also an inverse correlation between serum 25(OH)D levels and fat mass index (FMI) among women, suggesting that higher supplementation with vitamin D is needed as weight increases. The results of this study suggest that supplementation with vitamin D may be most beneficial in older populations who have low baseline physical functioning. © 2013 American Society for Bone and Mineral Research.     

Anthropometric measurements in male breast cancer

Background: 1% of breast cancers occur in men.The etiology is obscure. An elevated BMI has been postulated to be a cause. Methods: All male breast cancer patients operated from January 1990 to May 2001 were retrospectively reviewed. Relation between BMI and male breast cancer was examined. Results: 43 males underwent breast surgery for breast cancer during this period. 3 patients were excluded from the study because of other risk factors for breast cancer.The average BMI of 40 patients was 26.54 kg/m², which is mildly above the level for normal weight. Conclusions: Excessive adipose tissue may increase risk of male breast cancer.     

Patient Motivation for Bariatric Surgery: Characteristics and Impact on Outcomes

Background: Motivation for seeking obesity surgery has not been studied. The authors explored the patient's motivation for selecting surgery and examined for a relationship between primary motivating factors and weight outcomes. Methods: 208 (177F: 31M) unselected participants followed at least 1 year after Lap-Band? placement completed a short questionnaire. 6 statements were scored 1-6 from the most important through to the least important. Statements included appearance, embarrassment, medical conditions, health concerns, physical fitness and physical limitation. Any additional factors were also sought. Results: Mean age, weight and BMI before surgery were 41±10 years, 129±16 kg and 46±8 kg/m² respectively. Responses to appearance and embarrassment correlated strongly and were grouped together. Medical conditions and health concerns account for 52%, appearance and embarrassment for 32%, and poor physical fitness and physical limitation for 16% of first choices. Those who scored 1 for appearance or embarrassment (n=67) had a lower presenting BMI (44 kg/m², P=0.03) and all but 1 were female (P<0.001). This group reported more depressive symptoms, poorer mental quality of life and poorer body image preoperatively. Men were more likely than women to be motivated by medical problems (P=0.007). Subjects motivated by a medical condition were more likely to have hypertension or diabetes and less likely to smoke. This group tended to be older. Weight history did not influence motivation. The first choice of motivating factor was not associated with weight outcomes at 1-3 years following surgery. Conclusion: Health issues dominate the motivation for seeking surgery. Weight outcomes do not appear to be affected by the patient's primary motivating factor.     

Hemochromatosis,<Emphasis Type="Italic"> HFE</Emphasis> C282Y Homozygosity,and Bariatric Surgery: Report of Three Cases

Background: Iron absorption is decreased in some individuals who have undergone bariatric surgery. Methods: We evaluated measures of iron metabolism and therapeutic phlebotomy in 3 adults with hemochromatosis and HFE C282Y homozygosity who underwent bariatric surgery. Results: 1 male and 1 female had surgery before diagnosis of hemochromatosis (jejuno-ileal bypass and Roux-en-Y gastric bypass, respectively); neither had iron overload. Another man was treated with serial phlebotomy to induce iron depletion; later, he underwent Roux-en-Y gastric bypass. His maintenance phlebotomy requirement for hemochromatosis decreased substantially (on average ~1 unit each 71 days before surgery, and ~1 unit each 173 days after surgery). None of these patients developed iron deficiency, and none took supplemental iron. Conclusions: Iron absorption is decreased in some patients with hemochromatosis and HFE C282Y homozygosity after bariatric surgery, but their risk of developing iron deficiency may be diminished.     

Clinical Predictors of Sleep Apnea in Patients Undergoing Bariatric Surgery

Background: Sleep apnea is a frequent and unappreciated condition of morbidly obese patients. If unrecognized it could lead to significant postoperative complications. A clinical tool to assess the severity of sleep apnea is not available.We prospectively determined whether the Epworth Sleepiness Scale (ESS) or body mass index (BMI) predict the severity of sleep apnea in morbidly obese patients. Methods: 66 consecutive patients evaluated for bariatric surgery from June to November 1999 were examined and prospectively administered a health questionnaire including the ESS. Patients with an ESS ≥ 6 were referred for polysomnography with calculation of Respiratory Disturbance Index (RDI). Sleep apnea was graded as mild (RDI 6-20), moderate (RDI 21-40) and severe (RDI>40). Clinical variables such as BMI and ESS score were compared using regression analysis. Data are mean ± SEM. Results: 4 men and 23 women (27/66) who scored >6 on the ESS completed a sleep study. Mean ESS was 13 ± 4.5. Sleep apnea was mild in 13 patients, moderate in 7, severe in 6, and absent in 1. Mean age was 43 ± 9.5 years. BMI was 52 ± 10 kg/m². Linear regression analysis did not demonstrate correlation between ESS score and severity of sleep apnea (r²=0.03, p>0.05). Multiple regression analysis demonstrated no correlation between BMI, patient snoring, and RDI score. Conclusions: Sleep apnea is frequent in candidates screened for bariatric surgery. ESS is a useful tool to investigate daytime sleepiness and other manifestations of sleep apnea. However, the ESS does not predict the severity of sleep apnea. Clinical suspicion of sleep apnea should prompt polysomnography.     

Obesity Correlates with Gastroesophageal Reflux

Thirty morbidly obese patients presenting forbariatric surgery were evaluated for symptomatic andobjective evidence of gastroesophageal reflux. Sixteenpatients had heartburn while 14 were asymptomatic. All underwent esophageal function testing;manometry was performed in all patients, pH monitoringin 28. Patients with esophageal pH < 4 for more than5% of observed time weighed more than those with normal acid exposure, 165.2 vs 129.8 kg (P <0.01), and had significantly higher body mass indices,56.5 vs 48.3 kg/m² (P < 0.05). Similarly,morbidly obese patients with abnormal reflux scores weighed significantly more and hadgreater body mass indices than patients with normalscores (P < 0.05). Lower esophageal sphincterpressure was higher in patients with normal esophagealacid exposure than in those with abnormal findings,15.5 vs 12.5 mm Hg (P < 0.05). This studydemonstrates a correlation between both weight and bodymass index with gastroesophageal reflux.