Current advances concerning the most cited metal ions doped bioceramics and silicate-based bioactive glasses for bone tissue engineering

Studies related to biomaterials that stimulate the repair of living tissue have increased considerably, improving the quality of many people's lives that require surgery due to traumatic accidents, bone diseases, bone defects, and reconstructions. Among these biomaterials, bioceramics and bioactive glasses (BGs) have proved to be suitable for coating materials, cement, scaffolds, and nanoparticles, once they present good biocompatibility and degradability, able to generate osteoconduction on the surrounding tissue. However, the role of biomaterials in hard tissue engineering is not restricted to a structural replacement or for guiding tissue regeneration. Nowadays, it is expected that biomaterials develop a multifunctional role when implanted, orchestrating the process of tissue regeneration and providing to the body the capacity to heal itself. In this way, the incorporation of specific metal ions in bioceramics and BGs structure, including magnesium, silver, strontium, lithium, copper, iron, zinc, cobalt, and manganese are currently receiving enhanced interest as biomaterials for biomedical applications. When an ion is incorporated into the bioceramic structure, a new category of material is created, which has several unique properties that overcome the disadvantages of primitive material and favors its use in different biomedical applications. The doping can enhance handling properties, angiogenic and osteogenic performance, and antimicrobial activity. Therefore, this review aims to summarize the effect of selected metal ion dopants into bioceramics and silicate-based BGs in bone tissue engineering. Furthermore, new applications for doped bioceramics and BGs are highlighted, including cancer treatment and drug delivery.     

Recent Biophysical Issues About the Preparation of Solute-Filled Lipid Vesicles

Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations.     

Electrospun microporous gelatin–polycaprolactone blend tubular scaffold as a potential vascular biomaterial

The work reported involved the fabrication of an electrospun tubular conduit of a gelatin and polycaprolactone (PCL) blend as an adventitia‐equivalent construct. Gelatin was included as the matrix for increased biocompatibility with the addition of PCL for durability. This is contrary to most of the literature available for biomaterials based on blends of gelatin and PCL where PCL is the major matrix. The work includes the assiduous selection of key electrospinning parameters to obtain smooth bead‐free fibres with a narrow distribution of pore size and fibre diameter. Few reports elucidate the optimization of all electrospinning parameters to fabricate tubular conduits with a focus on obtaining homogeneous pores and fibres. This stepwise investigation would be unique for the fabrication of gelatin–PCL electrospun tubular constructs. The fabricated microfibrous gelatin–PCL constructs had pores of size ca 50–100 μm reportedly conducive for cell infiltration. The measured value of surface roughness of 57.99 ± 17.4 nm is reported to be favourable for protein adhesion and cell adhesion. The elastic modulus was observed to be similar to that of the tunica adventitia of the native artery. Preliminary in vitro and in vivo biocompatibility tests suggest safe applicability as a biomaterial. Minimal cytotoxicity was observed using MTT assay. Subcutaneous implantation of the scaffold demonstrated acute inflammation which decreased by day 15. The findings of this study could enable the fabrication of smooth bead‐free microfibrous gelatin–PCL tubular construct as viable biomaterial which can be included in a bilayer or a trilayer scaffold for vascular tissue engineering. © 2019 Society of Chemical Industry     

An application of chemometric techniques to analyze the effects of the wave function modifications on the intermolecular stretching frequencies of the hydrogen-bonded complexes

Factorial design and principal component models are used to determine how ab initio H-bond stretching frequencies depend on characteristics of the molecular orbital wave functions of acetylene–HX, ethylene–HX and cyclopropane–HX π-type hydrogen complexes with X=F, Cl, CN, NC and CCH. The results obtained for the three sets of complexes show that factorial design and principal component analyses complement each other. Factorial design calculations clearly show that these frequencies are affected mostly by inclusion of electron correlation on the calculation level. On average, their values are increased by about 25 cm⁻¹ due to a change from the Hartree–Fock (HF) to Möller–Plesset 2 (MP2) level. Valence, diffuse and polarization main effects as well as valence–diffuse, diffuse–correlation and polarization–correlation interaction effects are also important to better describe a factorial model to the H-bond stretching frequencies of these hydrogen complexes. This simplified model has been successful in reproducing the complete ab initio results, which correspond to two hundred and forty calculations. Principal component analyses applied only to hydrogen-bonded complexes whose experimental frequencies are known, has revealed that the six-dimensional original space can be accurately represented by a bidimensional space defined by two principal components. Its graphical representation reveals that the experimental intermolecular stretching frequencies are in closest agreement with the MP2/6–31+G and MP2/6–311+G ab initio results.     

Live animal performance, carcass traits, and meat palatability of calf- and yearling-fed cloned steers

Two groups of Brangus steers produced by nuclear transplantation cloning were used in parallel studies investigating the impact of calf- and yearling-feeding. The first group (n = 8) were fed as calves (CF; n = 4) or yearlings (YF; n = 4) to a constant age end point of 16 mo. The second group (n = 10) were fed as calves (CF; n = 5) or yearlings (YF; n = 5) to a constant live weight end point (530 kg). When slaughtered at the same age, CF and YF steers did not differ (P > .05) in feedlot ADG, but the CF steers were heavier and had higher dressing percentages, numeric yield grades, and quality grades (P < .05). Top loin steaks from the groups of steers did not differ (P > .05) in palatability traits. When fed to a constant live weight, the YF steers gained more rapidly (P < .05) and had lower (P < .05) numeric yield grades than did CF steers. Again CF steers had higher (P < .05) dressing percentages. There was no difference (P > .05) between the treatments in carcass quality grade or meat palatability characteristics. Thus, when finished to a constant weight end point, YF steers gained more rapidly, with no adverse effects on carcass quality grade or palatability traits; however, CF steers consistently produced higher dressing percentages, largely due to greater external fatness.     

Longitudinal weight changes, length of survival, and energy requirements of long-term care residents with dementia

OBJECTIVE: We hypothesized that institutionalized patients with dementia, who frequently have feeding problems and require supervised and assisted feeding, would lose more weight during their residency than nondemented, independently functioning residents and have compromised survival. To test this hypothesis, we examined the survival and longitudinal changes in weight of two cohorts of institutionalized residents with dementia and compared these cohorts with a cohort of nondemented residents. We also measured the resting energy expenditures of a subset of the subjects with dementia as an indicator of their energy needs. DESIGN: A longitudinal cohort study with retrospective baseline chart review and subsequent follow-up of monthly weights and mortality over 4 years. SETTING: A 725-bed long-term care institution with specified levels of care. SUBJECTS: Two cohorts of residents with dementia, one consisting of subjects who required total care throughout their institutional stay (n = 31) and another group who did not initially require total care (n = 48); these were compared with a cohort with normal mentation who were functionally independent in their daily activities (n = 26). The total number of subjects was 105. MEASUREMENTS: Demographics, medical problems, and medications by chart review; functional and mental status evaluations; longitudinal monthly weights and mortality for the 48-month study period; and resting energy expenditures by indirect calorimetry. MAIN RESULTS: Residents with dementia had lower weights on admission and throughout their stay than nondemented, independently functioning residents, and they were more likely to have a weight loss of 10 lbs or more at some point during the 4-year study period. However, their mean weights did not change during the study period. The mean survival from admission of those demented residents who died was more than 3 years. Resting energy expenditures of women residents with advanced dementia were 12% lower than predicted from the Harris Benedict equations. CONCLUSION: Dementia is not necessarily associated with unremitting weight loss during institutionalization despite the frequent occurrence of feeding difficulties and temporary weight loss. This may be caused partly by the lower than expected resting energy expenditures and, hence, energy needs of affected residents as their dementia progresses. Demented residents weighed significantly less than nondemented, independently functioning residents throughout their institutional stay. Nevertheless, nursing staff are able to maintain weight and survival for extended periods even in very impaired residents.     

Preparation and characterization of chitosan‐based dispersions

Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry