Human periosteum cell osteogenic differentiation enhanced by ionic silicon release from porous amorphous silica fibrous scaffolds.

Current synthetic grafts for bone defect filling in the sinus can support new bone formation but lack the ability to stimulate or enhance osteogenic healing. To promote such healing, osteoblast progenitors such as human periosteum cells must undergo osteogenic differentiation. In this study, we tested the hypothesis that degradation of porous amorphous silica fibrous (PASF) scaffolds can enhance human periosteum cell osteogenic differentiation. Two types of PASF were prepared and evaluated according to their densities (PASF99, PASF98) with 99 and 98% porosity, respectively. Silicon (Si) ions were observed to rapidly release from both scaffolds within 24 h in vitro. PASF99 Si ion release rate was estimated to be nearly double that of PASF98 scaffolds. Mechanical tests revealed a lower compressive strength in PASF99 as compared with PASF98. Osteogenic expression analysis showed that PASF99 scaffolds enhanced the expression of activating transcription factor 4, alkaline phosphatase, and collagen (Col(I)α1, Col(I)α2). Scanning electron microscopy showed cellular and extracellular matrix (ECM) ingress into both scaffolds within 16 days and the formation of Ca-P precipitates within 85 days. In conclusion, this study demonstrated that PASF scaffolds enhance human periosteum cell osteogenic differentiation by releasing ionic Si, and structurally supporting cellular and ECM ingress.

Overview and recommendations for medical screening and diagnostic evaluation for postdeployment lung disease in returning US warfighters.

OBJECTIVE: To review inhalational exposures and respiratory disease risks in US military personnel deployed to Iraq and Afghanistan and to develop consensus recommendations for medical screening and diagnostic referral. METHODS: A Working Group of physicians and exposure scientists from academia and from the Departments of Defense and Veterans Affairs was convened in February 2010. RESULTS: Despite uncertainty about the number of people affected and risk factors for adverse pulmonary outcomes in this occupational setting, the Working Group recommended: (1) standardized approaches to pre- and postdeployment medical surveillance; (2) criteria for medical referral and diagnosis; and (3) case definitions for major deployment-related lung diseases. CONCLUSIONS: There is a need for targeted, practical medical surveillance for lung diseases and for a standardized diagnostic approach for all symptomatic deployed personnel.

The impact of incomplete vaccination schedules on the magnitude and duration of protective antigen-specific IgG responses in recipients of the US licensed anthrax vaccine.

Using a cross-sectional analysis design, we measured serum anti-protective antigen (PA) concentrations in individuals receiving six or fewer US licensed anthrax vaccinations. Samples were collected from 363 individuals with a mean of 29.6+/-8.42 months after their last vaccination (range 3-57 months). An enzyme-linked immunosorbent assay (ELISA) developed and validated by the Centers for Disease Control and Prevention (CDC) was used to evaluate the range and status of anthrax vaccine-induced serum antibody concentrations. A significant correlation (r=0.73, P< or =0.001) was found to exist between the number of vaccinations received and specific anti-PA immunoglobulin G (IgG) concentrations. We observed two discrete groups comprised of one to three doses (5.9-11.7 microg/ml) and four to six doses (26.2-30.2 microg/ml). These data indicate that anti-PA IgG is present at low but detectable levels after as few as two vaccinations (5.9+/-6.43 microg/ml). These findings may have significance for anthrax vaccine recipients who are unable to complete the primary or full regimen with this licensed product.

Evaluation of field dental equipment in a deployment environment.

Dental officers and technicians must have reliable, durable, well-performing field dental equipment to enable them to provide dental care to deployed troops in operational environments. Unfortunately, no organized program exists to test such equipment before its purchase and use in the field. This article presents the results of a project conducted by the Naval Institute for Dental and Biomedical Research and the Air Force Dental Evaluation and Consultation Service to evaluate commercially available field dental equipment through laboratory testing and clinical-user evaluations in theater. The purpose of this 2-year project was to identify the best-performing and most cost-effective field dental equipment for possible future procurement. Initial laboratory testing was performed at the Naval Institute for Dental and Biomedical Research, and the equipment was then shipped to Kuwait for in-theater environmental and clinical-user testing. A seven-member scientific team of military dental officers and technicians was deployed for 1 month to perform in-theater testing under regional environmental conditions and to coordinate clinical-user evaluations. The testing provided beneficial results by identifying equipment that performed properly and equipment that exhibited shortcomings serious enough to render it inadequate for operational use. It is recommended that the project serve as a model for future testing and evaluation of medical/dental equipment by all of the military services.

Interactions of the DNA intercalator acridine orange, with itself, with caffeine, and with double stranded DNA.

Caffeine (CAF) inhibits the intercalation of acridine orange (AO) into cellular DNA. Optical absorption and fluorescence spectroscopy were employed to determine the molecular interactions of AO with itself, with CAF, and with double stranded herring sperm DNA (dsDNA). AO dimerization was observed at concentrations >2 micromol. The sharp increase in fluorescence (lambda(em)=530 nm) at 5 micromol of AO was attributed to AO multimer formation. From 0.5 to 5.0 micromol, the AO self-association binding constant (K(assoc)) was determined to be 38620 mol(-1), however, the presence of 150 mmol NaCl increased K(assoc) to 118000 mol(-1) attributed to the charge neutralization. The K(assoc) for AO with CAF was confirmed to be 256 mol(-1). K(assoc) for the binding of AO with 20 micromol DNA ranged from, 32000 mol(-1) at 2 micromol AO, to approximately 3700 mol(-1) at 10 micromol AO, in the absence of NaCl. This AO concentration dependency of K(assoc) value with DNA was attributed to AO intercalation into dsDNA at high dsDNA/AO ratios, and electrostatic binding of AO to dsDNA at low AO ratios. The findings provide information used to explain fluorescence intensity values at lambda(em) at 530 nm from studies that combine AO, caffeine, and dsDNA.

Caffeine and other xanthines as cytochemical blockers and removers of heterocyclic DNA intercalators from chromatin.

Caffeine (CAF) and other xanthines non-covalently bind with the cationic fluorescent dye acridine orange (AO) and with other heterocyclic mutagens and carcinogens that are known to intercalate into double-stranded DNA (dsDNA). Fluorescence microscopy and spectrofluorometry studies were employed to test the ability of caffeine and certain other methyl substituted xanthines, with different binding affinities for AO, to inhibit and to reverse the intercalation of AO and other heterocyclic agents from intercalation with the DNA of nuclear chromatin of air-dried cells. Results indicated that xanthines with binding affinity for AO greater than 150 m(-1) block the AO molecule in a concentration dependent manner and comply with mass action kinetics. Thus CAF and other xanthines can be used to either inhibit intercalation of AO into nuclear DNA or to remove AO once intercalated into nuclear DNA. The interactions between other planar heterocyclics, xanthines, and nuclear chromatin dsDNA were also found to be non-covalent. Studies are needed to determine the ability of CAF and other xanthines to block and/or remove polyaromatic hydrocarbon (PAH) intercalators from the DNA of living cells.