Biogas production from the mechanically pretreated, liquid fraction of sorted organic municipal solid wastes.

The high liquid content in fruit and vegetable wastes makes it convenient to mechanically separate these wastes into mostly liquid and solid fractions by means of pretreatment. Then, the liquid fraction can be treated using a high-rate anaerobic biofilm reactor to produce biogas, simultaneously reducing the amount of solids that must be landfilled. In this work, the specific composition of municipal solid waste (MSW) in a public market was determined; then, the sorted organic fraction of municipal solid waste was treated mechanically to separate and characterize the mostly liquid and solid fractions. Then, the mesophilic anaerobic digestion for biogas production of the first fraction was evaluated. The anaerobic digestion resulted in a reduced hydraulic retention time of two days with high removal of chemical oxygen demand, that is, 88% on average, with the additional benefit of reducing the mass of the solids that had to be landfilled by about 80%.

Strategies for the startup of methanogenic inverse fluidized-bed reactors using colonized particles.

One of the inconveniences in the startup of methanogenic inverse fluidized-bed reactors (IFBRs) is the long period required for biofilm formation and stabilization of the system. Previous researchers have preferred to start up in batch mode to shorten stabilization times. Much less work has been done with continuous-mode startup for the IFBR configuration of reactors. In this study, we prepared two IFBRs with similar characteristics to compare startup times for batch- and continuous-operation modes. The reactors were inoculated with a small quantity of colonized particles and run for a period of 3 months, to establish the optimal startup strategy using synthetic media as a substrate (glucose as a source of carbon). After the startup stage, the continuous- and batch-mode reactors removed more than 80% of the chemical oxygen demand (COD) in 51 and 60 days of operation, respectively; however, at the end of the experiments, the continuous-mode reactor had more biomass attached to the support media than the batch-mode reactor. Both reactors developed fully covered support media, but only the continuous-mode reactor had methane yields close to the theoretical value that is typical of stable reactors. Then, a combined startup strategy was proposed, with industrial wastewater as the substrate, using a sequence of batch cycles followed by continuous operation, which allows stable operation at an organic loading rate of 20 g COD/L x d in 15 days. Using a fraction of colonized support as an inoculum presents advantages, with respect to previously reported strategies.

Rofecoxib, a specific cyclooxygenase-2 inhibitor, in primary dysmenorrhea: a randomized controlled trial.

OBJECTIVE: To determine whether rofecoxib is effective for treating primary dysmenorrhea and whether cyclooxygenase-2 is involved in the pathophysiology of primary dysmenorrhea. METHODS: A double-masked, randomized, placebo and active-comparator-controlled clinical trial including 127 subjects with histories of primary dysmenorrhea was conducted in an outpatient clinical research center. Subjects were randomly assigned to placebo, rofecoxib 25 or 50 mg followed by 25 mg every 24 hours as needed, or naproxen sodium 550 mg every 12 hours as needed for up to 3 days. Subjects took all four treatments in a balanced, complete-block, crossover design. Measurements included self-administered questionnaires of analgesic efficacy, spontaneous reports of adverse experiences, physical examinations, and laboratory safety tests. RESULTS: Rofecoxib 25 and 50 mg provided analgesic efficacy greater than placebo (P < or = .006) for the primary endpoint of total pain relief over the first 8 hours. For other efficacy endpoints (sum of the pain intensity difference over the first 8 hours, subject's global evaluation, peak pain relief, peak pain intensity difference, and time to remedication) both doses of rofecoxib were better than placebo (P < or = .006) and were not distinguishable from naproxen sodium for all efficacy endpoints. All treatments were well tolerated. CONCLUSION: Rofecoxib effectively treated primary dysmenorrhea, and cyclooxygenase-2-derived prostanoids play a role in the pathophysiology of primary dysmenorrhea.

Pruebas de tamizaje para la detección de errores congénitos del metabolismo / Screenin tests for inborn errors of metabolism

Existe un gran número de errores congénitos del metabolismo asociados a anormalidades clínicas entre las que destaca el retardo mental, y que pueden prevenirse si se detecta y aplica la terapia adecuada y portuna. En este trabajo se presentan los resultados obtenidos aplicando pruebas de tamizaje metabólico (PTM) en 1485 muestras de orina de pacientes de la consulta pediátrica del Hospital General de Zona No. 21 y Hospital Regional de Especialidades No. 25, así como de clínicas del IMSS en el área metropolitana de Monterrey, Nuevo León, a las cuales se les realizaron pruebas químicas cualitativas para la determinación de aminoácidos, mucopolisacáridos, ácidos orgánicos y azúcares, así como cromatográficas. En una segunda ocasión solamente 44.83 y 57.02 por ciento respectivamente, dieron nuevamente una prueba positiva, por lo que se sugiere que médico responsable debe de enviar una segunda muestra con información sobre factores que puedan influir en los resultados