Extreme rainstorms drive exceptional organic carbon export from forested humid-tropical rivers in Puerto Rico.

Extreme rainfall events in the humid-tropical Luquillo Mountains, Puerto Rico export the bulk of suspended sediment and particulate organic carbon. Using 25 years of river carbon and suspended sediment data, which targeted hurricanes and other large rainstorms, we estimated biogenic particulate organic carbon yields of 65 ± 16 tC km-2 yr-1 for the Icacos and 17.7 ± 5.1 tC km-2 yr-1 for the Mameyes rivers. These granitic and volcaniclastic catchments function as substantial atmospheric carbon-dioxide sinks, largely through export of river biogenic particulate organic carbon during extreme rainstorms. Compared to other regions, these high biogenic particulate organic carbon yields are accompanied by lower suspended sediment yields. Accordingly, particulate organic carbon export from these catchments is underpredicted by previous yield relationships, which are derived mainly from catchments with easily erodible sedimentary rocks. Therefore, rivers that drain petrogenic-carbon-poor bedrock require separate accounting to estimate their contributions to the geological carbon cycle.

Natural attenuation of volatile organic compounds (VOCs) in the leachate plume of a municipal landfill: using alkylbenzenes as process probes.

More than 70 individual VOCs were identified in the leachate plume of a closed municipal landfill. Concentrations were low when compared with data published for other landfills, and total VOCs accounted for less than 0.1% of the total dissolved organic carbon. The VOC concentrations in the core of the anoxic leachate plume are variable, but in all cases they were found to be near or below detection limits within 200 m of the landfill. In contrast to the VOCs, the distributions of chloride ion, a conservative tracer, and nonvolatile dissolved organic carbon, indicate little dilution over the same distance. Thus, natural attenuation processes are effectively limiting migration of the VOC plume. The distribution of C2-3-benzenes, paired on the basis of their octanol-water partition coefficients and Henry's law constants, were systematically evaluated to assess the relative importance of volatilization, sorption, and biodegradation as attenuation mechanisms. Based on our data, biodegradation appears to be the process primarily responsible for the observed attenuation of VOCs at this site. We believe that the alkylbenzenes are powerful process probes that can and should be exploited in studies of natural attenuation in contaminated ground water systems.

Blood cells and plasma proteins of chickens fed a diet supplemented with (1-->3),(1-->6)-beta-D-glucan and enrofloxacin.

The effects of (1-->3),(1-->6)-beta-D-glucan from Saccharomyces cerevisiae and of the fluochinolone enrofloxacin were studied on red and white blood cells and plasma proteins of growing chickens up to the 35th day of life. The prominent findings within the leukocyte population on a per cent scale are: (i) increase of leukocyte count; increase of neutrophils and decrease of lymphocytes in the control and in the antibiotic group from day 17 to day 35; (ii) a minor decrease of neutrophils and no change of lymphocytes in the glucan group; (iii) the monocytes increase from 2.5 +/- 1.8% to 6.5 +/- 7.6% in the glucan group; (iv) the basophils increase in the control group and scale down in the other groups from day 17 to day 35. The total count of leukocytes increases in the controls and in the glucan group. The total protein content of blood plasma, beta-globulin and gamma-globulin increase and the albumin-globulin-ratio and alpha-globulin decline during chickens growth. These changes are most prominent in the glucan group. The haemoglobin concentration shows in all three dietary groups a highly significant increase from day 17 to day 35 by about 17 to 27 per cent; no changes are seen in packed cell volume and number of erythrocytes per litre blood.

Diclofenac concentrations in synovial fluid and plasma after cutaneous application in inflammatory and degenerative joint disease.

1. Ten patients with bilateral knee joint effusions were treated topically with a gel containing 1 g diclofenac/100 g (80 mg three times daily). They were randomized to receive diclofenac gel to one knee and a placebo gel preparation to the other knee. 2. Diclofenac was assayed in synovial fluid and blood plasma by GC/ECD as the pentafluorobenzyl-ester derivative. 3. Total concentrations of diclofenac in synovial fluid (day 4) were significantly higher in the diclofenac gel treated knee than in the contralateral placebo treated knee (25.5 +/- 3.6 ng ml-1 vs 21.6 +/- 2 ng ml-1; P less than 0.05). These concentrations were lower than total plasma drug concentrations (40.6 +/- 4.7 ng ml-1, n = 10, P less than 0.01). Unbound concentrations of diclofenac in synovial fluid from either the diclofenac gel treated or the placebo treated knee were not significantly different from each other or from plasma free concentrations (115 +/- 16 and 99 +/- 12 vs 108 +/- 19 pg ml-1). 4. Clinical parameters showed improvement of joint mobility and a small reduction of swelling (circumference) in both knees with time. However, the differences between knees were not significant. 5. We conclude that direct transport of diclofenac from the skin into the ipsilateral knee joint after cutaneous application is minimal. Distribution seems to be predominantly via the blood. Whether the observed improvements of clinical parameters were due to drug effects or to the spontaneous course of the underlying disease cannot be distinguished.

Qualitative testing for circulating immune complexes by use of zone electrophoresis on agarose.

On binding of antibody to antigen an immune complex is formed that has a net surface charge different from that of either of the two components. This, together with clonal restriction of the antibody response, gives rise to distinctive patterns that are readily apparent in stained agarose gels after routine zone electrophoresis. Most circulating immune complexes appear as a rectangular pattern, with well-defined edges, located in the gamma-region. The identity of the material responsible for these patterns has been established by three different experimental approaches: analysis of tetanus/anti-tetanus complexes formed in vitro, analysis of sera from rabbits with experimental immune complex disease, and analysis of human type II and type III cryoglobulins. Studies of reproducibility, interfering substances, and correlation with other assays for detecting immune complexes indicate that zone electrophoresis in agarose gel is a sensitive, highly specific technique for immune complex detection, of potential value as a screening tool.