RESUMEN
PURPOSE: This manuscript describes the value of and proposal for a high-level architectural framework for a Public Health Grid (PHGrid), which the authors feel has the capability to afford the public health community a robust technology infrastructure for secure and timely data, information, and knowledge exchange, not only within the public health domain, but between public health and the overall health care system. METHODS: The CDC facilitated multiple Proof-of-Concept (PoC) projects, leveraging an open-source-based software development methodology, to test four hypotheses with regard to this high-level framework. The outcomes of the four PoCs in combination with the use of the Federal Enterprise Architecture Framework (FEAF) and the newly emerging Federal Segment Architecture Methodology (FSAM) was used to develop and refine a high-level architectural framework for a Public Health Grid infrastructure. RESULTS: The authors were successful in documenting a robust high-level architectural framework for a PHGrid. The documentation generated provided a level of granularity needed to validate the proposal, and included examples of both information standards and services to be implemented. Both the results of the PoCs as well as feedback from selected public health partners were used to develop the granular documentation. CONCLUSIONS: A robust high-level cohesive architectural framework for a Public Health Grid (PHGrid) has been successfully articulated, with its feasibility demonstrated via multiple PoCs. In order to successfully implement this framework for a Public Health Grid, the authors recommend moving forward with a three-pronged approach focusing on interoperability and standards, streamlining the PHGrid infrastructure, and developing robust and high-impact public health services.
Asunto(s)
Centers for Disease Control and Prevention, U.S./organización & administración , Difusión de la Información/métodos , Internet/organización & administración , Objetivos Organizacionales , Administración en Salud Pública/métodos , Estados UnidosRESUMEN
This study investigates the histomorphologic and functional effects of external-beam irradiation on peripheral nerve regeneration in the rat model. All animals received a 1.5-cm interposition isogeneic nerve graft to the right posterior tibial nerve. Group 1 animals served as controls and Groups 2 and 3 received fractionated postoperative irradiation doses of 66 and 106 Gy, respectively. All animals were evaluated for functional recovery with monthly walking-track analysis. At the end of 8 months, the animals were sacrificed and segments of the grafted and distal nerve were harvested for histomorphologic analysis. A statistically significantly fewer number of axons were found in the distal segment of the irradiated specimens, compared to controls. There was no significant difference in the nerve-fiber density of the grafted or distal segments, compared to controls. Functional evaluation by walking-track analysis showed no difference between the irradiated groups and controls over the length of the study. These results suggest that acute nerve grafting of nerve defects in the face of planned postoperative irradiation is safe.
Asunto(s)
Regeneración Nerviosa/efectos de la radiación , Radioterapia de Alta Energía/métodos , Nervio Tibial/efectos de la radiación , Animales , Femenino , Estudios de Seguimiento , Masculino , Periodo Posoperatorio , Pronóstico , Dosis de Radiación , Ratas , Ratas Sprague-Dawley , Valores de Referencia , Nervio Tibial/fisiología , Nervio Tibial/cirugía , Trasplante de Tejidos/métodosRESUMEN
We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve, long bone, intestine, or blood vessel.
Asunto(s)
Materiales Biocompatibles/química , Regeneración Tisular Dirigida/métodos , Ácido Láctico/química , Ácido Poliglicólico/química , Polímeros/química , Rastreo Diferencial de Calorimetría , Fenómenos Químicos , Química Física , Regeneración Tisular Dirigida/instrumentación , Microscopía Electrónica de Rastreo , Tamaño de la Partícula , Poliésteres , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Porosidad , TemperaturaRESUMEN
The purpose of this study was to evaluate the effects of preoperative external cobalt60 beam irradiation on nerve regeneration. Ninety 250-g male Sprague-Dawley rats were studied. Peripheral nerve regeneration was measured by walking track analysis and histomorphology of the proximal, grafted, and distal nerve segments. Ninety animals were randomly assigned to one of five treatment groups, receiving a total fractionated dose of 30, 50, 70, and 90 Gy. Each animal received a 15-mm interposition nerve graft into the right posterior tibial nerve 6 weeks following completion of radiation therapy. The left leg served as a control. The remaining 10 animals received a nerve isograft subjected to a single dose of 30 Gy prior to placement (group 5). Walking track analysis was performed monthly through 8 months. At the conclusion of 120 and 240 days, sections of the proximal, grafted, and distal nerve were harvested, stained, and examined histomorphologically. Evaluation of the print length index demonstrated no statistical difference between our previously established nonirradiated controls, the irradiated groups, and the irradiated isograft group (group 5). The total number of axons per square millimeter was significantly decreased in the distal segment of all irradiated groups when compared with the controls. No statistical difference in number of axons per square millimeter was noted in the irradiated isograft group. Furthermore, no statistical difference was noted in the nerve fiber density between the control group, the preoperative irradiated groups, or the irradiated isograft group (group 5). Despite the reduction in myelinated regenerating fibers, no reduction in function was observed as measured by walking track analysis. Thus, immediate reconstruction of peripheral nerve defects in the face of preoperative irradiation may not be contraindicated.
Asunto(s)
Radioisótopos de Cobalto , Regeneración Nerviosa/efectos de la radiación , Nervio Tibial/fisiología , Nervio Tibial/efectos de la radiación , Animales , Miembro Posterior , Masculino , Cuidados Preoperatorios , Dosis de Radiación , Distribución Aleatoria , Ratas , Ratas Sprague-Dawley , Nervio Tibial/cirugíaRESUMEN
OBJECTIVE: To examine a possible relationship between prophylactic antibiotic therapy (PAT) and the development of Clostridium difficile toxin (CDT) positivity. DESIGN: Retrospective case-control study. SETTING: Tertiary care medical center in New York, NY. PATIENTS: A total of 357 patients, admitted from November 1992 to April 1994, with positive. CDT assays. Of these, 23 patients (6%) received only PAT for elective surgical procedures. Thirty-nine patients were matched as controls for age, sex, and surgical procedure. MAIN OUTCOME MEASURES: Both CDT positivity and inappropriate use of PAT. RESULTS: Appropriate PAT was used in 26 (42%) of 62 patients (17% cases, 56% controls). The Mantel-Haenszel estimator for the summary odds ratio for the development of CDT positivity from inappropriate use of PAT was 5.1 (95% confidence interval, 1.10 to 23.64). Main duration between the operation and the final antibiotic dose was significantly longer in the CDT-positive group compared with the control group (3.1 vs 1.7 days, P < .05). The length of hospital stay was significantly longer in the CDT-positive group compared with the control group (16.5 vs 10.2 days, P < .05). CONCLUSIONS: The prolonged use of PAT in elective surgical cases increases the risk of developing CDT positivity. The appropriate use of PAT could significantly reduce health costs by eliminating unnecessary doses of antibiotics, by decreasing the rate of CDT positivity, and by shortening the hospital stay. Restrictive policies may need to be implemented to prevent further antibiotic misuse.