Enhancement of acellular biomineralization, dental pulp stem cell migration, and differentiation by hybrid fibrin gelatin scaffolds.

OBJECTIVE: The current in vitro study aims to evaluate cross-linked hydrogels with and without the addition of fibrin that could potentially be used in endodontic regeneration as a scaffold material. METHODS: Synthesis of gelatin/fibrin scaffold, and performing nanoscale characterization using cryo-electron microscopy, dynamic rheology, and XRF for structure property relations; plating dental pulp stem cells and determining mineralization, migration, and differentiation using rt-PCR, XRF, and Raman spectroscopy. RESULTS: Cryo electron imaging shows gelatin and fibrin, when gelled separately to form classical rectangular cross-linked networks, where the modulus scales inversely with the cube root of the mesh size. When gelled together, a network with a fundamentally different structure is formed, which has higher ductility and when placed as a scaffold in osteogenic media, produces twice the mineral content. Immunofluorescence, RT-PCR and Rahman Spectroscopy indicate that the hybrid gel enhances cell migration, induces odontogenic differentiation of dental pulp stem cells, and promotes formation of dentin. SIGNIFICANCE: The mechanical properties of the hybrid gel scaffold enhance in-migration of stem cells and subsequent differentiation, which are critical for regenerative procedures. Under acellular conditions, placement of the hybrid gel enhances biomineralization, which would strengthen the root if used as a scaffold for endodontic regeneration. Our in vitro findings are consistent with previous in vivo studies which show improved mineralization when bleeding is induced into the canal, given that fibrin is a primary component in blood clotting. Therefore, insertion of the hybrid gelatin-fibrin scaffold could enable more reproducible and consistent outcomes if used for regenerative endodontic treatment (RET).

Mortality in captive baboons with seizures: a new model for SUDEP?

Because the baboon is a model of primary generalized epilepsy, we were interested in mortality of captive animals with a history of witnessed seizures. Causes of natural death were investigated in 46 seizure baboons (SZ) and 78 nonepileptic controls (CTL), all of which underwent a complete pathologic examination at the Southwest Foundation for Biomedical Research (SFBR) in San Antonio. SZ animals died at a younger age than the control baboons (p < 0.001). Almost all epileptic baboons that died suddenly without an apparent cause (SZ-UKN), had pulmonary congestion or edema without evidence of trauma, systemic illness, or heart disease, compared to nine controls (12%) (p < 0.001), most of which demonstrated evidence of a concurrent illness. Serosanguineous bronchial secretions were found in 15 SZ-UKN baboons (58%), but in only three controls (4%) (p < 0.001). Chronic multifocal fibrotic changes in myocardium were noted in only three (12%) of SZ-UKN baboons and one control baboon. Based upon these results, untreated seizures appear to reduce the life expectancy of captive baboons. Sudden unexpected death in epilepsy (SUDEP) may be a common cause of natural death in epileptic baboons.

Chest tube placement in children during extracorporeal membrane oxygenation (ECMO).

BACKGROUND: Pleural collections of air and fluid are frequent in infants and children treated with extracorporeal membrane oxygenation (ECMO). In this anticoagulated population, chest tube placement is potentially hazardous, and catastrophic hemorrhage has been reported. We sought to define the risks associated with chest tube placement in a large population of children managed with ECMO. METHODS: The records of 189 consecutive children managed with ECMO at two children's hospitals were reviewed. Demographics, indications for ECMO, and ECMO courses were reviewed. In particular, the occurrence of pleural collections and the frequency and technique of chest tube placement were evaluated. The incidence of complications and mortality were determined. RESULTS: The median age of the subjects was 2days. The overall mortality was 26.5%. A pneumothorax was found in 19 (10.1%), a pleural effusion in 26 (13.8%), and a hemothorax in 2 (1.0%). A chest tube was placed in 27 (19 by a needle-guide wire technique and 8 by cut-down). Major bleeding complications occurred in 6 subjects (22%). CONCLUSIONS: There was a significant incidence of major bleeding complications and death in subjects in whom chest tubes were placed. The placement of a chest tube during ECMO should be done only if it is likely to improve pump flow or promote weaning of support.