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in tissue engineering, endochondral ossification (EO) is often replicated by chondrogenically differentiating mesenchymal stromal cells (MSCs) in vitro and achieving bone formation through in vivo implantation. The resulting marrow-containing bone constructs are promising as a treatment for bone defects. However, limited bone formation capacity has prevented them from reaching their full potential. This is further complicated since it is not fully understood how this bone formation is achieved. Acellular grafts derived from chondrogenically differentiated MSCs can initiate bone formation; however, which component within these decellularised matrices contribute to bone formation has yet to be determined. Collagen type X (COLX), a hypertrophy-associated collagen found within these constructs, is involved in matrix organisation, calcium binding and matrix vesicle compartmentalisation. However, the importance of COLX during tissue-engineered chondrogenesis and subsequent bone formation is unknown. The present study investigated the importance of COLX by shRNA-mediated gene silencing in primary MSCs. A significant knock-down of COLX disrupted the production of extracellular matrix key components and the secretion profile of chondrogenically differentiated MSCs. Following in vivo implantation, disrupted bone formation in knock-down constructs was observed. The importance of COLX was confirmed during both chondrogenic differentiation and subsequent EO in this tissue engineered setting.

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Endochondral ossification (EO) is the process by which the long bones of the body form and has proven to be a promising method in tissue engineering for achieving cell-mediated bone formation. The present review centred on state-of-the-art research pertaining to mesenchymal stem cells (MSCs)-mediated endochondral bone formation, focusing on the role of donor cells, extracellular matrix and host immune cells during tissue-engineered bone formation. Possible research avenues to improve graft outcome and bone output were highlighted, as well as emerging research that, when applied to tissue-engineered bone grafts, offers new promise for improving the likelihood of such grafts transition from bench to bedside.

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With limited autologous and donor bone graft availability, there is an increasing need for alternative graft substitutes. We have previously shown that chondrogenically priming mesenchymal stem cell (MSC) pellets for 28 d in vitro will reproducibly result in endochondral bone formation after in vivo implantation. However, pellet priming time for clinical applications is quite extensive. A micropellet (µpellet)-fibrin construct was developed and coupled, with a shorter priming period, determined by an in vitro time course experiment. In vitro data showed expression of chondrogenic genes and matrix production after 7 d of chondrogenic priming, indicating that briefer priming could possibly be used to induce bone formation in vivo. 7 and 28 d primed pellet, pellet-fibrin and µpellet-fibrin constructs were cultured for in vitro analysis and implanted subcutaneously for 8 weeks into nude mice. µpellet-fibrin constructs, cultured in vitro for 7 or 28 d, produced comparable bone to standard pellets in vivo. MSC-mediated bone formation was achieved following only 7 d of in vitro priming. Bone formation in vivo appeared to be influenced by overall matrix production pre-implantation. Given this short priming time and the injectable nature of the µpellet-fibrin constructs, this approach might be further developed as an injectable bone substitute, leading to a minimally-invasive treatment option, which would allow for tailored filling of bone defects.

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As the main immunocytes lining pulmonary alveoli, alveolar macrophages (AM) are critical to the maintenance of immune hemostasis of the lung. This study examined the capacity of AM obtained from healthy individuals in comparison with autologous blood monocytes (MN) to produce transforming growth factor-beta 1 (TGF-beta), a pivotal molecule in regulation of immune responses and in promotion of fibrosis. AM produced negligible TGF-beta in response to LPS at both 24 and 72 h of culture. In contrast, LPS induced significant levels of TGF-beta in MN cultures (79.5 +/- 35 pg/ml in AM vs 890 +/- 162 pg/ml in MN, p less than 0.001, at 24 h). AM also produced significantly less TGF-beta than MN in response to phorbol ester and Con A. By northern blot analysis, constitutive expression of TGF-beta mRNA was lower in AM than MN at the time of isolation and after 24 h of culture. Lower expression of steady state TGF-beta message was not due to a more rapid decay of its mRNA in AM. Furthermore, TGF-beta mRNA expression was up-regulated by rTGF-beta in MN but was not induced in AM. In contrast to TGF-beta, LPS-stimulated AM produced sixfold higher levels of TGF-alpha at 24 h than MN (p less than 0.01). Production of IL-10 by LPS-stimulated AM was sixfold lower than MN (p less than 0.005) at 24 h of culture, but was comparable with MN at 72 h. Both 10-day cultured monocytes and peritoneal macrophages also had reduced capacity to produce TGF-beta. Therefore, the inability to produce TGF-beta may be a feature of more differentiated mononuclear phagocytes. In health, the reduced expression of TGF-beta by AM and the intact ability to produce TGF-alpha and IL-10 may favor a timely and regulated host response to inhaled pathogens while limiting potentially deleterious inflammatory responses.

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Power Doppler ultrasound is a color-coded Doppler ultrasound method based on the strength of the Doppler shift signal. The sensitivity for slow flow was tested with different flow phantoms. The lowest detectable velocity was 0.04 cm/s in a water- or oil-filled tank at an angle of 45 degrees and 0.24 cm/s in an oil medium at an angle of 86 degrees. The pulse repetition frequency (PRF) was 100 kHz at the lowest detectable velocities, the acquisition time depended mostly on the attenuation of the medium. The new method depended very little on the angle of insonation. Under ideal conditions detectable flow velocities are within the range of mean capillary flow velocity.

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Luxatio erecta, or inferior shoulder dislocation, is a rare form of shoulder dislocation. The case of a patient presenting with bilateral luxatio erecta, which was initially felt by EMS personnel to be an hysterical reaction, is discussed. An awareness of this rare entity, the potential-associated musculoskeletal and neurovascular injuries, and the proper treatment are essential for emergency physicians.

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When recombinant-DNA-derived methionyl growth hormone (met-GH) became available for patients resuming treatment, we were able to compare dose intervals in 47 prepubertal children with growth hormone deficiency. Patients were randomly assigned to one or three doses weekly or to daily injections for a total dosage of 0.3 mg/kg weekly. If the patient's annual growth failed to increase more than 2 cm above baseline, the dose interval was changed from weekly to three times a week or from three times a week to daily. In the second year of the study, all patients received daily injections. Despite a mean duration of previous treatment with growth hormone of more than 3 years, daily injections in 16 patients throughout the first year of the study resulted in a mean growth velocity (9.6 +/- 2.4 cm) comparable to that in newly treated patients given met-GH three times weekly in other trials. Administration by daily injection was more effective than injection three times per week (P less than .05) in 13 patients (7.9 +/- 2.1 cm) or once a week in four patients (7.7 +/- 1.2 cm). Second year growth velocities in 21 patients who had received once-a-week or three-times-a-week injections the first year of the study, increased significantly with a change to daily injection (7.7 +/- 2.2 vs 8.8 +/- 1.9 cm) (P less than .05).

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Failure to develop a proper routine for complete examination and documentation of the injured hand may result in the inability to make the proper diagnosis. Less than optimal treatment may result. Ultimately, the end result is unnecessary functional loss and, frequently, medical-legal difficulties. Initial emergency department management of acute hand is reviewed: recognition of surgical emergencies, proper initial treatment of tendon and nerve injuries, splinting, and record keeping are emphasized.

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