Aligned electrospun polymer fibres for skeletal muscle regeneration.

Skeletal muscle repair is often overlooked in surgical procedures and in serious burn victims. Creating a tissue-engineered skeletal muscle would not only provide a grafting material for these clinical situations, but could also be used as a valuable true-to-life research tool into diseases affecting muscle tissue. Electrospinning of the elastomer PLGA produced aligned fibres that had the correct topology to provide contact guidance for myoblast elongation and alignment. In addition, the electrospun scaffold required no surface modifications or incorporation of biologic material for adhesion, elongation, and differentiation of C2C12 murine myoblasts.

Can quantitative capnometry differentiate between cardiac and obstructive causes of respiratory distress?

STUDY OBJECTIVE: To determine whether quantitative measurement of end-tidal carbon dioxide (ETCO2) can differentiate between cardiac and obstructive causes of respiratory distress. DESIGN: Prospective observational study. SETTING: Emergency department (ED) of a tertiary care hospital. PATIENTS: Adult patients who presented to the ED with moderate-to-severe dyspnea. Patients were excluded if they were unable to cooperate with the performance of peak expiratory flow rate (PEFR) or ETCO2 tests, were younger than 18 years of age, or had received prehospital intervention for their respiratory distress. INTERVENTIONS: Physicians obtained an ETCO2 level and PEFR prior to ED pharmacologic intervention. A hand-held capnometer with digital read-out was used to obtain the ETCO2 level. The patient's age, sex, initial vital signs, breath sounds and medication history, the presence or absence of diaphoresis and/or orthopnea, the duration of symptoms, the chest radiograph interpretation, and final diagnosis were also recorded. MEASUREMENTS AND RESULTS: Forty-two patients were eligible for inclusion in the analysis. The mean ETCO2 level was 31.1+/-9.4 mm Hg; the mean PEFR was 161.3+/-53.1 L/min. The ETCO2 levels for pulmonary edema/congestive heart failure (CHF) patients differed significantly from those of asthma/COPD patients (27.1+/-7.8 mm Hg vs 33.4+/-9.6 mm Hg; p=0.0375). However, no single ETCO2 level was found to be a reliable predictor of diagnosis. CONCLUSION: ETCO2 levels for pulmonary edema/CHF patients differ significantly from those of asthma/COPD patients. However, no single ETCO2 level reliably differentiates between the two disease processes.

Craniofacial osteoblast responses to polycaprolactone produced using a novel boron polymerisation technique and potassium fluoride post-treatment.

There is no ideal material for craniofacial bone repair at present. The aim of this study was to test the biocompatibility of polycaprolactone (PCL) synthesised by a novel method allowing control of molecular weight and degradation rate, with regard to it being used as matrix for a biodegradable composite for craniofacial bone repair. Human primary craniofacial cells were used, isolated from paediatric skull after surgery. Cell responses were analysed using various assays and antibody staining. Cells attached and spread on the PCL in a similar manner to the Thermanox controls as shown by phalloidin staining of F-actin. Cells maintained the osteoblast phenotype as demonstrated by alkaline phosphatase assay and antibody staining throughout the time points studied, up to 28 days. Cells proliferated on the PCL as shown by a DNA assay. Collagen-1 staining showed extensive production of a collagen-1 containing extracellular matrix, which was also shown to be mineralised by alizarin red staining. Short-term (up to 48 h) attachment studies and long-term (up to 28 days) expression of markers of the osteoblast phenotype have been demonstrated on the PCL. This new method of synthesising PCL shows biocompatibility characteristics that give it potential to be used for craniofacial bone repair.

Do pulse checks cause a significant delay in the initial defibrillation sequence?

This study was undertaken to determine if checking for a pulse between initial defibrillations causes a clinically significant delay in the administration of the defibrillations. Ten emergency department nurses and 10 emergency medicine resident physicians were timed delivering three successive defibrillations (200, 300 and 360 J) to a manikin under three randomly assigned scenarios: (1) without pulse checks; (2) with pulse checks performed by an assistant; and (3) with pulse checks performed by the participant. All participants performed the three defibrillation scenarios using three different models of defibrillators. Repeated measures analysis of variance was used to compare mean defibrillation times for the three scenarios. The mean time was 20.4 +/- 1.0 s for defibrillation without pulse checks; 20.2 +/- 1.2 s with pulse checks by an assistant and 22.0 +/- 2.0 s with pulse checks by the participant. There was a statistically significant difference between no pulse checks and pulse checks by the participant. No statistically significant difference was noted between no pulse checks and pulse checks by an assistant. We conclude that checking for a pulse does cause a statistically significant delay in the administration of defibrillations. This difference, however, is not likely to be clinically relevant.

Osteoblast attachment and mineralized nodule formation on rough and smooth 45S5 bioactive glass monoliths.

Human primary osteoblast responses to smooth and roughened bioactive glass of 45S5 (Bioglass trade mark ) composition (46.1% SiO(2), 26.9% CaO, 2.6% P(2)O(5), 24.4% Na(2)O) were analysed in vitro. The smooth and rough surfaces had R(a) values and peak to valley distances of 0.04, 4.397, 2.027, and 21.328 microm, respectively. Cell attachment and morphology was observed using phalloidin staining of the actin cytoskeleton and revealed significant differences between smooth and rough surfaces. Cells that were spiky in appearance on the rough compared to the smooth surface formed an organized actin matrix much later on the rough surface. Scanning electron microscopy revealed many cell filipodia extending from more rounded cell bodies on the rough surface. A significantly greater number of nodules on the rough surface was observed, and these were shown to mineralize when supplemented with beta-glycerophosphate and dexamethasone. Raman spectroscopy confirmed the presence of hydroxyapatite in the mineralized cultures showing a definite peak at 964 cm(-1). FTIR analysis showed hydroxyapatite formation occurred more rapidly on the rough surface. This study demonstrates that although initial cell morphology was less advanced on the roughened surface, the cells were able to form mineralized nodules in greater numbers. This may have implications to bone tissue engineering using bioactive glasses.

Long-term craniofacial osteoblast culture on a sodium phosphate and a calcium/sodium phosphate glass.

The aim of this study was to determine the characteristics of human craniofacial osteoblasts cultured on sodium phosphate glass and calcium-sodium phosphate glass in a long-term culture of up to 28 days. The characteristics studied were attachment, proliferation, alkaline phosphatase activity, collagen-1 production, and mineralization. A comparison of the degradation rate, measured by mass loss of the glasses, which are intended for use as a component of a novel degradable composite for craniofacial bone repair, was also performed. It was our hypothesis that the glass would be degradable with a change in degradation rate observed by calcium addition and support osteoblast proliferation and expression of the above characteristics. The inclusion of calcium into the reaction mixture significantly decreased the degradation rate, and it is suggested that the slower degradation is the result of pseudo crosslinking (ionic crosslinks rather than covalent bonding) of the polyphosphate chains by the calcium ions. Therefore, twice as many P-O bonds will need to be hydrolyzed for dissolution of the metal phosphate to occur, therefore greatly reducing the rate of hydrolysis. Osteoblasts were able to attach, spread, and proliferate in a manner comparable with the positive control, as shown by analysis of variance. Formation of a collagen-rich mineralized matrix was also observed. The results presented here suggest that a biocompatible soluble glass has been produced, which has potential to be included in a novel biodegradable craniofacial implant.

Osteoblast responses to tape-cast and sintered bioactive glass ceramics.

The advantage of tape-cast bioactive glasses lies in the manufacturing procedure, which allows the build-up of layers and, therefore, the production of complex shapes. This, therefore, has applications to tissue engineering, where specific shapes are required such as repair of craniofacial defects. The bioactivity of tape-cast discs sintered at temperatures ranging from 800 degrees C to 1000 degrees C and for 3 or 6 h was analyzed by FTIR. Tape-cast discs were used to culture primary human osteoblasts, and cell attachment, cell death, collagen production, nodule formation, and mineralization were studied. These responses were dependent upon Si and Na release profiles of the tape-cast discs, and development of the hydroxyapatite layer.

In vitro evaluation of novel bioactive composites based on Bioglass-filled polylactide foams for bone tissue engineering scaffolds.

Highly porous poly(DL-lactic acid) (PDLLA) foams and Bioglass-filled PDLLA composite foams were characterized and evaluated in vitro as bone tissue engineering scaffolds. The hypothesis was that the combination of PDLLA with Bioglass in a porous structure would result in a bioresorbable and bioactive composite, capable of supporting osteoblast adhesion, spreading and viability. Composite and unfilled foams were incubated in simulated body fluid (SBF) at 37 degrees C to study the in vitro degradation of the polymer and to detect hydroxyapatite (HA) formation, which is a measure of the materials' in vitro bioactivity. HA was detected on all the composite samples after incubation in SBF for just 3 days. After 28 days immersion the foams filled with 40 wt % Bioglass developed a continuous layer of HA. The formation of HA for the 5 wt % Bioglass-filled foams was localized to the Bioglass particles. Cell culture studies using a commercially available (ECACC) human osteosarcoma cell line (MG-63) were conducted to assess the biocompatibility of the foams and cell attachment to the porous substrates. The osteoblast cell infiltration study showed that the cells were able to migrate through the porous network and colonize the deeper regions within the foam, indicating that the composition of the foams and the pore structures are able to support osteoblast attachment, spreading, and viability. Rapid formation of HA on the composites and the attachment of MG-63 cells within the porous network of the composite foams confirms the high in vitro bioactivity and biocompatibility of these materials and their potential to be used as scaffolds in bone tissue engineering and repair.

Controlled degradation and macrophage responses of a fluoride-treated polycaprolactone.

We have developed a new bone replacement material based on polycaprolactone (PCL), which can act as a suitable matrix for monomer transfer molding of degradable composites. A boron trifluoride catalyst with glycerol additive was used to produce PCL with a degradation rate that can be altered by treatment with fluoride ions. The effect of cations on the degradation of the polymer and macrophage cell responses are discussed. We found that treatment with fluoride ions reduced the degradation rate. No significant difference between these three fluorides was observed although a general trend was seen where KF-treated PCL appeared to degrade slower than NaF-treated PCL which was slower than NH(4)F-treated PCL. Variation in solubilities of the salts was observed where the K(+) cation had the highest solubility and the Na(+) cation had the lowest solubility, which suggests that NaF was able to degrade the polymer more efficiently than the other fluorides. No significant macrophage activation was observed after culture on the polymer surfaces as determined by peroxide and IL-1 beta release, whereas some activation occurred after culture in degradation products.

In vitro bioactivity of S520 glass fibers and initial assessment of osteoblast attachment.

Bioactive glass fibers are attractive materials for use as tissue-engineering scaffolds and as the reinforcing phase for resorbable bioactive composites. The bioactivity of S520 glass fibers (52.0 mol % SiO(2), 20.9 Na(2)O, 7.1 K(2)O, 18.0 CaO, and 2.0 P(2)O(5)) was evaluated in two media, simulated body fluid (SBF) and Dulbecco's modified Eagle's medium (DMEM), for up to 20 days at 37 degrees C. Hydroxyapatite formation was observed on S520 fiber surfaces after 5 h in SBF. After a 20-day immersion, a continuous hydroxyapatite layer was present on the surface of samples immersed in SBF as well as on those samples immersed in DMEM [fiber surface area to solution volume ratio (SA:V) of 0.10 cm(2)/mL]. Backscattered electron imaging and EDS analysis revealed that the hydroxyapatite layer formation was more extensive for samples immersed in SBF. Decreasing the SA:V ratio to 0.05 cm(2)/mL decreased the time required to form a continuous hydroxyapatite surface layer. ICP was used to reveal Si, Ca, and P release profiles in DMEM after the 1st h (15.1, 83.8, and 29.7 ppm, respectively) were similar to those concentrations previously determined to stimulate gene expression in osteoblasts in vitro (16.5, 83.3, and 30.4 ppm, respectively). The tensile strength of the 20-microm diameter fibers was 925 +/- 424 MPa. Primary human osteoblast attachment to the fiber surface was studied by using SEM, and mineralization was studied by using alizarin red staining. Osteoblast dorsal ruffles, cell projections, and lamellipodia were observed, and by 7 days, cells had proliferated to form monolayer areas as shown by SEM. At 14 days, nodule formation was observed, and these nodules stained positive for alizarin red, demonstrating Ca deposition and, therefore mineralization.

Complications of a retrograde intubation in a trauma patient.

The authors report the case of an elder woman involved in a motor vehicle collision (MVC) requiring emergent intubation using the technique of retrograde intubation (RI). Since RI is a blind technique, potential complications arising from its use are numerous and may result in increased morbidity and mortality. Such was the case of this RI that involved incorrect placement of the endotracheal tube (ETT), resulting in suboptimal ventilation and increased morbidity. Additionally, this case illustrates how the failure to detect this error in multiple settings (ambulance, helicopter, emergency department) led to unnecessary and potentially deleterious procedures and significant delay in providing the basics of trauma care, oxygenation and ventilation. Although theoretical complications of RI have been addressed in the past, there have been very few published reports of actual complications. The emergency physician must be aware of difficult airways, options available to establish alternative airways, and methods to confirm appropriate placement of the ETT. The authors also discuss the indications, procedures, and complications involved in performing an RI.

Are emergency department patients at risk for herb-drug interactions?

OBJECTIVES: To determine the prevalence of herbal and/or dietary supplement use and identify patients at risk for herb-drug interactions. METHODS: A convenience sample of 944 patients were surveyed to determine the prevalence and types of supplements used. Patients with heart disease, diabetes, psychiatric disorders, and/or hypertension were assessed for potential interactions. RESULTS: One hundred thirty-five (14.3%) patients reported regular use. Of these, 79.3% were taking supplements concurrently with prescription medications, and 80.0% were administered medication(s) in the emergency department. Cardiac: 19.8% (n = 33) reported regular use, with four potential interactions. Hypertension: 20.3% (n = 54) reported regular use, with two potential interactions. Diabetes: 15.9% (n = 20) reported regular use, with no known interactions. Psychiatric: 15.9% (n = 10) reported regular use, with one potential interaction. CONCLUSIONS: Six patients were identified at risk for seven known herb-drug interactions. The prevalence of undisclosed herbal supplement use and lack of research on these supplements suggest that more patients may be at risk.

Exertional rhabdomyolysis in a body builder abusing anabolic androgenic steroids.

Rhabdomyolysis, or acute skeletal muscle destruction, may be accompanied by myoglobinaemia, myoglobinuria, and an elevated serum creatine kinase level. This disorder has many potential causes. In this article, the authors describe a case of rhabdomyolysis occurring after vigorous weight lifting by a man who was supplementing his weight-training programme with the intake of anabolic androgenic steroids dispensed to him by a colleague.

Do pulse checks delay semiautomatic defibrillation by EMT-defibrillators?

Advanced cardiac life support (ACLS) guidelines from the American Heart Association (AHA) now recommend not checking for a pulse between the initial three defibrillations for pulseless patients in ventricular tachycardia or fibrillation. The AHA asserts that checking for a pulse needlessly delays defibrillation. This study was undertaken to determine if pulse checks delay defibrillation by EMT-Defibrillators (EMT-Ds) using a semiautomatic defibrillator (SAED). Twenty-seven EMT-Ds demonstrated delivery of three successive defibrillations during two test scenarios: once with and once without pulse checks after the first and second defibrillations. The time from the first to third defibrillation was recorded. The mean time to deliver the defibrillations was 60.2 +/- 6.2 seconds with pulse checks and 57.5 +/- 4.6 seconds without pulse checks. The difference, 2.7 +/- 5.9 seconds, was statistically significant (P = 0.026). Pulse checks by EMT-Ds do delay administration of defibrillations, but consideration should be given to reinstating pulse checks as a part of the AHA guidelines, since this delay is of questionable clinical significance.

Determination of prehospital blood glucose: a prospective, controlled study.

STUDY OBJECTIVE: To determine if emergency medical personnel can effectively rule out hypoglycemia in the prehospital setting. DESIGN: During a 10-week period, emergency medical personnel determined the fingerstick glucose on all prehospital patients with altered mental status using the Chemstrip bG. Statistical comparisons were made to serum glucose levels performed by hospital laboratory personnel on blood samples obtained prior to glucose administration. A serum glucose level less than 60 mg/dL was considered a positive test for hypoglycemia. PARTICIPANTS: 170 consecutive patients with altered mental status (AMS) ranging in age from 13 to 90 years were enrolled. MEASUREMENTS AND MAIN RESULTS: Of these patients, 158 were normal or hyperglycemic, 12 were hypoglycemic, and one patient was hypoglycemic but had only a borderline negative fingerstick test. Thus, a sensitivity of 91.7% and a negative predictive value of 99.3% were obtained. The specificity was 92.4%, and positive predictive value was 47.8%. CONCLUSION: The Chemstrip bG may be used safely in the prehospital setting to rule out hypoglycemia.

Does the ambulance environment adversely affect the ability to perform oral endotracheal intubation?

OBJECTIVE: Oral endotracheal intubation (ETI) is the preferred method of controlling the airway in critically ill or injured patients. It was postulated that time could be saved if intubation was performed in the ambulance en route to the hospital. This study was designed to determine whether the ambulance environment adversely affected the ability of emergency medical technicians at the advanced-intermediate level (EMT-AI) to perform oral ETI. HYPOTHESIS: The restrictive environment of a moving ambulance would affect adversely the ability of EMT-AIs to perform ETI compared with a controlled setting. This would result in a significant increase in the time necessary to perform ETI in the ambulance compared with a controlled setting not complicated by restrictive space and motion. METHODS: Twenty on-duty EMT-AIs were recruited to volunteer for this prospective, nonrandomized, nonblinded trial. All participants performed three consecutive oral ETIs on an airway mannequin in two settings: 1) in the back of a moving ambulance; and 2) on a table in the rescue squad station. Of the participants, 10 performed the intubations in the ambulance first; the remainder performed the intubations at the station first. Time for intubation with the mannequin was recorded by stopwatch. The mean times for intubation in both settings were compared by Student's t-test (p < 0.05). RESULTS: All intubation attempts were successful. The mean time for intubation in the station was 13.0 +/- 3.4 seconds. The mean time in the ambulance setting was 13.2 +/- 5.3 seconds. There was no significant difference between the intubation times in the two settings (p = 0.88). CONCLUSION: The environment of a moving ambulance does not appear to hinder the ability of EMT-AIs to perform oral ETI in a laboratory setting with a mannequin model.

EMS knowledge and skills in rural North Carolina: a comparison with the National EMS Education and Practice Blueprint.

INTRODUCTION: Many state and local emergency medical services (EMS) systems may wish to modify provider levels and their scope of practice to align their systems with the recommendations of the National Emergency Medical Services Education and Practice Blueprint. To determine any changes that may be needed in a typical EMS system, the knowledge and skills of EMS providers in one rural area of North Carolina were compared with the knowledge and skills recommended in the National Emergency Medical Services Education and Practice Blueprint. METHODS: A survey listing 175 items of patient care-oriented knowledge and skills described in the National Emergency Medical Services Education and Practice Blueprint was developed. EMS providers from five rural eastern North Carolina counties were asked to identify on the survey those items of knowledge and skills they believed they possessed. The skills and knowledge selected by the respondents at the five different North Carolina levels of certification were compared with the knowledge and skills listed for comparable provider levels delineated by the National Emergency Medical Services Education and Practice Blueprint. The proportions of the recommended skills reported to be possessed by the respondents were compared to determine which North Carolina certification levels best correlate with the Blueprint. RESULTS: One hundred forty-five EMS providers completed the survey. The proportion of recommended skills and knowledge reported to be possessed by Emergency Medical Technicians (EMTs) ranked significantly lower than did the skills and knowledge reported to be possessed by respondents at other levels in five of the 10 Blueprint elements. The proportion of recommended skills and knowledge reported to be possessed by EMT-Defibrillator-level personnel ranked lower than did those reported to be possessed by respondents at other levels in seven of the 10 Blueprint elements. The proportion of recommended skills and knowledge reported to be possessed by EMT-Intermediates ranked lower than did those reported to be possessed by respondents at other levels in nine of the 10 Blueprint elements. The proportion of recommended skills and knowledge reported to be possessed by EMT-Advanced Intermediates ranked lower than were the skills and knowledge reported to be possessed by respondents at other levels in two of the 10 Blueprint elements. Finally, the proportion of recommended skills and knowledge reported to be possessed by EMT-Paramedics ranked lower than were those reported to be possessed by respondents at other levels in one of the 10 Blueprint elements. CONCLUSION: In North Carolina, combining the EMT and EMT-Defibrillator levels and eliminating the EMT-Intermediate level would create three levels of certification, which would be more consistent with levels recommended by the Blueprint. The results of this study should be considered in any effort to revise the levels of EMS certification in North Carolina and in planning the training curricula for bridging those levels. Other states may require similar action to align with the National Emergency Medical Services Education and Practice Blueprint.

Synthesis and characterization of a hybrid (chitosan-g-glycidyl methacrylate)-xanthan hydrogel.

This work reports the synthesis and characterization of a new material obtained by mixing the hybrid natural-synthetic chitosan-g-glycidyl methacrylate (CTS-g-GMA) biopolymer and xanthan gum (X). All materials were characterized by infrared spectroscopy (FTIR), X-ray diffraction, and thermal analysis (DSC and TGA) and the results were contrasted with those of the precursor materials. The swelling index of the hydrogels decreases when the GMA mass percentage increases. The X-ray diffraction patterns show that the hybrid hydrogels are amorphous in contrast to chitosan (CTS), which is semi-crystalline. FTIR analysis confirms the existence of physical interactions among constituents. Rheological properties, η, G', and G", were determined as a function of flow allowing one to conclude that (CTS-g-GMA)-X behaves as physical hydrogel. Additionally, we report viability of fibroblasts when cultured onto the synthesized hydrogels. This study shows that these hydrogels support cell viability and have potential for use in biomedical engineering applications.

Gel-cast glass-ceramic tissue scaffolds of controlled architecture produced via stereolithography of moulds.

Two glass-ceramic scaffolds with a simple cubic structure of 500 µm square ligaments and square channels of width 400 or 600 µm have been fabricated by gel-casting into moulds produced by stereolithography, followed by mould removal, polymer burnout and sintering. The scaffolds have crushing strengths of 41 ± 14 and 17 ± 5 Mpa, respectively. Using a method of assembling discrete slices of scaffold, we are able to study cell behaviour within a scaffold by disassembly. Both scaffold structures were seeded with primary human osteoblasts and these penetrate, adhere, spread and proliferate on the scaffold structure. The larger channel diameter scaffold shows a greater cell population (despite its smaller surface area) and more pronounced production of ECM components (collagen and mineralization) with increased time in culture. Studies of sectioned scaffolds show that cell density and ECM production decrease with depth and that the difference between the two scaffold architectures is maintained.

The Chemical and Physical Properties of Poly(ε-caprolactone) Scaffolds Functionalised with Poly(vinyl phosphonic acid-co-acrylic acid).

There is a clinical need for a synthetic alternative to bone graft substitute (BGS) derived from demineralised bone matrix. We report the electrospinning of Poly(ε-caprolactone) (PCL) to form a 3-dimensional scaffold for use as a synthetic BGS. Additionally, we have used Poly(vinyl phosphonic acid-co-acrylic acid) (PVPA) to improve bone formation. Fibres were formed using a 10% w/v PCL/acetone solution. Infrared spectroscopy confirmed that the electrospinning process had no effect on the functional groups present in the resulting structure. The electrospun scaffolds were coated with PVPA (PCL/PVPA), and characterised. The stability of the PVPA coating after immersion in culture medium was assessed over 21 days. There was rapid release of the coating until day 2, after which the coating became stable. The wettability of the PCL scaffolds improved significantly, from 123.3 ± 10.8° to 43.3 ± 1.2° after functionalisation with PVPA. The compressive strength of the PCL/PVPA scaffolds (72 MPa) was significantly higher to that of the PCL scaffold (14 MPa), and an intermediate between trabecular and cortical bone (7 MPa and 170 MPa, resp.). The study has demonstrated that the PCL/PVPA scaffold has the desired chemical and biomechanical characteristics required for a material designed to be used as a BGS.