Role of in Situ Natural Organic Matter in Mobilizing As during Microbial Reduction of FeIII-Mineral-Bearing Aquifer Sediments from Hanoi (Vietnam).

Natural organic matter (NOM) can contribute to arsenic (As) mobilization as an electron donor for microbially-mediated reductive dissolution of As-bearing Fe(III) (oxyhydr)oxides. However, to investigate this process, instead of using NOM, most laboratory studies used simple fatty acids or sugars, often at relatively high concentrations. To investigate the role of relevant C sources, we therefore extracted in situ NOM from the upper aquitard (clayey silt) and lower sandy aquifer sediments in Van Phuc (Hanoi area, Vietnam), characterized its composition, and used 100-day microcosm experiments to determine the effect of in situ OM on Fe(III) mineral reduction, As mobilization, and microbial community composition. We found that OM extracted from the clayey silt (OMC) aquitard resembles young, not fully degraded plant-related material, while OM from the sandy sediments (OMS) is more bioavailable and related to microbial biomass. Although all microcosms were amended with the same amount of C (12 mg C/L), the extent of Fe(III) reduction after 100 days was the highest with acetate/lactate (43 ± 3.5% of total Fe present in the sediments) followed by OMS (28 ± 0.3%) and OMC (19 ± 0.8%). Initial Fe(III) reduction rates were also higher with acetate/lactate (0.53 mg Fe(II) in 6 days) than with OMS and OMC (0.18 and 0.08 mg Fe(II) in 6 days, respectively). Although initially more dissolved As was detected in the acetate/lactate setups, after 100 days, higher concentrations of As (8.3 ± 0.3 and 8.8 ± 0.8 µg As/L) were reached in OMC and OMS, respectively, compared to acetate/lactate-amended setups (6.3 ± 0.7 µg As/L). 16S rRNA amplicon sequence analyses revealed that acetate/lactate mainly enriched Geobacter, while in situ OM supported growth and activity of a more diverse microbial community. Our results suggest that although the in situ NOM is less efficient in stimulating microbial Fe(III) reduction than highly bioavailable acetate/lactate, it ultimately has the potential to mobilize the same amount or even more As.

Nitric oxide inhibits vascular bioactivation of glyceryl trinitrate: a novel mechanism to explain preferential venodilation of organic nitrates.

Organic nitrates undergo enzymatic metabolization in the vasculature to release the active compound nitric oxide (NO). The resulting preferential venodilation has been suggested to be related to the vascular bioactivation process of organic nitrates because sodium nitroprusside, which is bioactivated differently, is not venoselective. We sought to determine whether NO has an influence on vascular bioconversion of organic nitrates because endogenous endothelial production of NO is smaller in veins than in arteries. Rings of porcine coronary arteries were subjected to radioactive glyceryl trinitrate (GTN) after preincubation with defined amounts of NO. The vascular content of GTN and the dinitrates (GDNs) 1,2-GDN and 1,3-GDN then was quantified. NO (3 microM, 30 min) significantly impaired bioactivation of GTN as indicated by a 30-50% reduction in the accumulation of 1,2-GDN and 1,3-GDN, whereas unchanged GTN was increased. Incubation with NO also reduced the stimulated specific activity of soluble guanylate cyclase isolated from human platelets. Its specific activity was reduced from 2.6 +/- 0.2 to 2.1 +/- 0.13 nmol of cGMP/mg/min. Relaxation studies with rings of porcine coronary arteries showed that NO-induced inhibition of vascular GTN metabolism and cGMP accumulation decreased the vasodilator potency of GTN by 10-fold. Further experiments showed that the duration of NO treatment is more important for this effect than the concentration of NO. We suggest that NO can inhibit vascular bioactivation of organic nitrates and might slightly desensitize soluble guanylate cyclase. The preferential venodilation induced by organic nitrates might be the result of the comparably low production of endogenous NO in veins.

A self-assessment of Wisconsin prehospital provider needs.

INTRODUCTION: The pressures facing emergency medical services (EMS) in Wisconsin and their effects on the delivery of prehospital emergency medical care were not known by the Wisconsin EMS Board. In an effort to assess these pressures and the needs of the emergency medical services in the State as perceived by the services, the Board undertook a survey of the EMS providers in Wisconsin. METHODS: A survey instrument was developed and approved by the EMS Board and distributed to all of the licensed emergency medical services in Wisconsin. RESULTS: Of the 453 survey instruments distributed, 323 (71.3%) were completed and returned. Intermediate- and paramedic-level services were more likely to respond than were the basic services, but 235 (72.8%) of the respondents identified their service levels as basic. In addition to providing information about the service characteristics, each responding service also rated the importance of their perceived needs. Lack of medical direction was perceived as the greatest need by all levels of service. However, the second greatest area of need for basic and intermediate services related to difficulty in recruiting new staff. For paramedic services, the second greatest need was associated with dispatching. When comparing services by rural versus urban, difficulty in recruiting new staff and collecting ambulance fees were seen as second and third to lack of a medical director by rural services, whereas urban services noted local training to be in the top three. In the assessment of educational needs, patient-care issues dominated. A review of written comments also demonstrated a difference between rural and urban services, but both noted Medicare and Medicaid reimbursement issues more commonly than any other problem. CONCLUSIONS: In the restructuring of health care, it will be important to consider the various needs of prehospital providers and recognize that such needs may be unique to the providers' location and level of service.

An assessment of prehospital provider needs in Wisconsin.

The Emergency Medical Systems Advisory Board assessed via questionnaire the needs of Wisconsin prehospital providers. Overall, 323 out of 453 (71.3%) of the services responded to the query. Intermediate and paramedic services were more likely to respond than those prehospital providers offering basic services. Of the respondents, however, 235 (72.8%) identified their service as basic. In addition to providing information about service characteristics, each responding provider also rated its perceived needs. All prehospital providers, regardless of service level, ranked "lack of medical director" as the issue of greatest concern. Continuing on, intermediate and basic providers rated difficulty in recruiting new staff as the second greatest need. Paramedic providers, however, identified dispatching as their second greatest need. Rural providers rated difficulty in recruiting new staff and difficulty in collecting ambulance fees as their second and third greatest needs, respectively. Urban providers, meanwhile, indicated difficulty in collecting ambulance fees and access to local training as the second and third top needs, respectively. With the proposed new curriculum for basic EMT services, the needs for local medical direction will be even greater.