Bioengineered human skeletal muscle capable of functional regeneration.

BACKGROUND: Skeletal muscle (SkM) regenerates following injury, replacing damaged tissue with high fidelity. However, in serious injuries, non-regenerative defects leave patients with loss of function, increased re-injury risk and often chronic pain. Progress in treating these non-regenerative defects has been slow, with advances only occurring where a comprehensive understanding of regeneration has been gained. Tissue engineering has allowed the development of bioengineered models of SkM which regenerate following injury to support research in regenerative physiology. To date, however, no studies have utilised human myogenic precursor cells (hMPCs) to closely mimic functional human regenerative physiology. RESULTS: Here we address some of the difficulties associated with cell number and hMPC mitogenicity using magnetic association cell sorting (MACS), for the marker CD56, and media supplementation with fibroblast growth factor 2 (FGF-2) and B-27 supplement. Cell sorting allowed extended expansion of myogenic cells and supplementation was shown to improve myogenesis within engineered tissues and force generation at maturity. In addition, these engineered human SkM regenerated following barium chloride (BaCl2) injury. Following injury, reductions in function (87.5%) and myotube number (33.3%) were observed, followed by a proliferative phase with increased MyoD+ cells and a subsequent recovery of function and myotube number. An expansion of the Pax7+ cell population was observed across recovery suggesting an ability to generate Pax7+ cells within the tissue, similar to the self-renewal of satellite cells seen in vivo. CONCLUSIONS: This work outlines an engineered human SkM capable of functional regeneration following injury, built upon an open source system adding to the pre-clinical testing toolbox to improve the understanding of basic regenerative physiology.

Inducing and Evaluating Skeletal Muscle Injury by Notexin and Barium Chloride.

Models of skeletal muscle injury in animal models are invaluable tools to assess muscle stem cell (MuSC)-mediated tissue repair. The optimization and comprehensive evaluation of these approaches have greatly improved our ability to assess MuSC regenerative potential. Here we describe the procedures for skeletal muscle injury with notexin and BaCl2 and assessment of the dynamics of tissue regeneration.

Comparison of standardized bariums with varying rheological parameters on swallowing kinematics in males.

This study measured dose-response of a range of commercially available liquid barium materials designed for use in videofluoroscopic oropharyngeal swallowing assessments, particularly as they relate to the necessity of adding a thickening agent for swallow safety. A group of 25 adult males representing various medical diagnoses consented to participate, with 16 qualifying to complete a videofluoroscopic swallowing assessment with liquid barium materials of three viscosities (nectar: 300 cP, thin honey: 1,500 cP, thick honey: 3,000 cP). Outcome measures included airway invasion (Penetration-Aspiration score), postswallow residue, and patient preference. Penetration-Aspiration and residue scores did not significantly differ between thin honey and thick honey bariums. Significantly more severe airway invasion was observed with nectar boluses than with two levels of honey boluses (p < 0.001). Significantly more residue was observed in the oral cavity (p < 0.002) and valleculae (p < 0.001) with thin and thick honey bariums than with nectar barium. Thin honey was rated as "easy" or "average" to drink by 67% of subjects, compared with 54% for thick honey. This study supports the use of thin honey barium over thick honey barium during videofluoroscopic swallowing assessments because the two honey bariums were comparable in terms of airway protection and postswallow residue in the oropharynx and the thin honey was preferred by patients.

An outbreak of granulomatous peritonitis caused by injectable selenium in a flock of Merino sheep.

During meat inspection, unusual pigmented lesions were found in the abdomens of 411 sheep from a flock raised in the Northern Tablelands of New South Wales. In each affected sheep there were multiple discrete, soft, yellow homogeneous plaques beneath the parietal peritoneum and extending into marginating facial planes of the diaphragm and body wall. Microscopically, the lesions consisted of focal granulomatous peritonitis with intracellular acicular refractile golden-brown crystals. Energy dispersive X-ray spectroscopy revealed intralesional barium and selenium, two components of an injectable selenium compound administered to the sheep 6-8 months prior, which contains the yellow pigment, iron oxide. The mechanism of subperitoneal deposition of the compound could not be confirmed, but is presumed to have involved intraperitoneal injection of barium selenate. Meat inspectors and diagnosticians should consider barium selenate injection-site granulomas as a possible explanation for yellow pigmented lesions, especially in livestock from selenium-deficient areas. Animal care providers should be aware that incorrect administration of barium selenate can result in losses from condemnation or downgrading of meat product.

Fires from the interaction of anesthetics with desiccated absorbent.

Rarely, fire and patient injury have resulted from the degradation of sevoflurane by desiccated carbon dioxide absorbent. Desiccated absorbent also can degrade desflurane and isoflurane, and in the present investigation we sought to determine whether a danger of fire also arose with their use in the presence of desiccated absorbent. Baralyme was desiccated by heating and directing a 10 L/min flow of oxygen through the absorbent. Approximately 1200 g of this desiccated absorbent was used to fill a standard absorber placed in a standard anesthetic circuit to which we directed a 6 L/min flow of oxygen containing 1.5 or 3.0 MAC desflurane, isoflurane, or sevoflurane. A 3-L reservoir bag served as a surrogate lung, and we ventilated this lung with a minute ventilation of 10 L/min. With desflurane or isoflurane, at both 1.5 MAC and 3.0 MAC, temperatures increased in 30 to 70 min to a peak of approximately 100 degrees C and then decreased. With 1.5 MAC sevoflurane (3.0 MAC was not studied), temperatures increased to over 200 degrees C, and in 2 of 5 studies, flames appeared in the anesthetic circuit. In a separate study, we found that concurrent delivery of carbon dioxide and desflurane did not increase peak temperatures. We conclude that the interaction of desflurane or isoflurane with desiccated absorbent is not likely to produce the conflagrations possible with sevoflurane.

Beneficial effects of human serum albumin on stability and functionality of alginate microcapsules fabricated in different ways.

A key engineering challenge in designing microcapsules made from biocompatible alginate is maintaining adequate exchange of nutrients and oxygen between the entrapped cells and the environment, while simultaneously avoiding swelling and subsequent failure of the microcapsule. Approval for the use of alginate in pharmaceutical and/or biomedical applications also strictly requires that the components of the microcapsule material must meet the safety criteria of the ASTM and FDA. Incorporation of foetal calf serum (FCS) into the microcapsules for stabilization is not in accordance with the guidelines affirmed by these organizations. FCS should be substituted by microcapsule-stabilizing additives that are medically approved. In this communication, it is shown that 10% FCS can be replaced by 1% human serum albumin (i.e. by an agent for which medical approval is granted) without compromising effects on long-term in vitro stability. Furthermore, it is demonstrated that human serum albumin (HSA) significantly enhances cell survival and, particularly, insulin secretion of encapsulated rat islets over a time period of 3 weeks when incubated in culture medium. Thus, HSA-stabilized microcapsules made from UHV(Lam) alginate are apparently a promising system for immunoisolation of cells, particularly when alginate is cross-linked by injection of BaCl(2) crystals into the alginate droplets. Slight adjustments of the alginate concentration can tailor the microcapsule permeability to the released therapeutic factor.

Dietary fecal tagging as a cleansing method before CT colonography: initial results polyp detection and patient acceptance.

PURPOSE: To compare reduced colonic cleansing based on dietary fecal tagging (FT) with standard (non-FT) colonic cleansing with regard to patient acceptance, sensitivity, and specificity. MATERIALS AND METHODS: In 50 patients (FT group), FT was performed by means of diet, magnesium citrate, and a barium suspension. In another 50 patients (non-FT group), preparation was based on polyethylene glycol administration. All patients underwent conventional colonoscopy after computed tomographic (CT) colonography. Sensitivity and specificity for polyp detection were calculated by using conventional colonography as the reference standard. At CT colonography, fecal residue was evaluated. Patients were interviewed to determine discomfort, side effects, sleep quality, final opinion on examination comfort, and whether they would be reluctant to undergo the same examination again. RESULTS: FT left more fecal residue but improved differentiation from polyps (FT specificity, 88% [30 of 34 patients]; non-FT, 77% [23 of 30 patients]). Sensitivities were comparable: FT, 88% (14 of 16 patients); non-FT, 85% (17 of 20 patients). FT significantly reduced discomfort, side effects, and sleep disturbance, and resulted in an improved final opinion of how comfortable the examination was (P <.05). Although FT improved patient willingness to repeat the examination, this improvement was not statistically significant (P >.05). CONCLUSION: FT offers the patient a well-tolerated preparation and improves specificity, with improved differentiation of polyps from residual stool.

Alcohol-induced vascular damage of brain is ameliorated by administration of magnesium.

Ethanol ingestion can cause irreversible neuronal and vascular damage in the brain and stroke-like events. Using an intact in vivo rat brain (pial) model, TV image-intensification, cultured cerebral vascular muscle cells, digital-image analysis, and a novel Mg2+ ion-selective electrode to measure extracellular ionized Mg2+, studies were designed to determine whether: 1) perivascular or systemic administration (i.v. or intra-arterial) of magnesium aspartate HCI (MgA) exert vasodilator effects on arterioles (65-130 microm o.d.) and venules (60-135 microm); 2) nonvasodilator doses of MgA could modify vascular spasms induced by BaCl2 and ethanol; 3) nonvasodilator doses of MgA could ameliorate or prevent the cerebral vascular damage induced by high doses of ethanol; and 4) ethanol depletes cerebral vascular muscle of intracellular Mg ions ([Mg2+]i). Perivascular application of MgA (0.01-100 micromol) produced dose-dependent vasodilatation of cerebral arterioles and venules; arterioles yielded greater vasodilator responses compared to venules. Nonvasodilator doses of Mg (1.0, 4.0 micromol/min), administered i.v. or intra-arterially, into a branch of the internal carotid artery, prevented: 1) the spasmogenic actions of ethanol and Ba2+; and 2) the vasculotoxic actions (rupture of postcapillary venules and focal hemorrhages) of ethanol. In addition, ethanol depleted cerebral vascular muscle cells of [Mg2+]i; blood levels of ionized Mg2+ rose after IP ethanol. Despite the fact that systemic infusion of low nonvasodilator doses did not result in dilatation of the pial arterioles and venules, plasma total and ionized Mg rose 18-230%, depending upon dose of MgA and time of plasma sampling. These data support the idea that Mg2+ can act as a local vasodilator on brain microvessels and possess antispasmodic properties on brain arterioles and venules. In addition, our results indicate that Mg may possess some unique cerebral vascular protective properties against the vasculotoxic effects of ethanol. Lastly, these findings suggest ethanol-induced cerebrovasospasm and vascular damage appear to be associated with a rapid loss of [Mg2+]i from cerebral vascular muscle cells.