Heavy metal and phosphorus content of fractions from manure treatment and incineration.

Alternative uses of pig manure are being considered, including separation and eventual incineration of the solid fraction to produce energy and ash. The efficiency of a screw press, a decanting centrifuge and chemical treatment in transferring N, P and heavy metals from slurry to a solid fraction were compared. Chemical treatment by coagulants and flocculants removed heavy metals most efficiently; they were transferred to the solid fraction in the order Zn > Cu > Cd by all three types of equipment. With centrifugation the heavy metal load on land where the solid fraction was applied was very low, whereas on land where the liquid fraction was applied it was only slightly less than that from un-separated manure. Conversely, chemical treatment resulted in a heavy metal load similar to that from un-separated manure with the solid fraction, while with the liquid fraction it was reduced to 20% of that from un-separated manure. Incineration of the solid fraction produces bottom ash and fly ash containing high levels of P. Most of the P and less than 10% of Cd is present in the bottom ash, producing an ash low in Cd content and a fly ash high in Cd. However, Cu and Ni tend to accumulate in the bottom ash. Chemical extraction procedures revealed that P-availability was high in all liquid and solid fractions except the bottom ash from incineration where approximately 80% of the P was transformed into a form of apatite. Since more bottom ash than fly ash is being formed, significant amounts of P may be immobilized by incineration of solid fractions.

The relationship between desmopressin treatment and voiding pattern in children.

OBJECTIVE: To collect data on voiding patterns at baseline (no treatment) and during short-term desmopressin treatment, with special reference to the functional and the mean bladder capacity. PATIENTS AND METHODS: The study included 120 children (aged 6-16 years) with monosymptomatic nocturnal enuresis. While at home they recorded their fluid intake and diuresis in two separate periods, i.e. 2 weeks as a baseline registration and another 2 weeks during desmopressin titration. On four study days the children recorded the time and volume of all voids and of fluid intake. From the diaries their functional and mean bladder capacities, 24-h diuresis and day/night ratio of diuresis were determined. RESULTS: The mean 24-h diuresis was significantly lower during short-term desmopressin treatment. In most of the enuretics the mean day/night ratio increased on desmopressin treatment. The mean functional and mean bladder capacities were unaffected by desmopressin. Those not responding had bladder capacities of approximately 100 mL less than full responders. Regardless of response, practically all the enuretics in the study had a smaller functional bladder capacity than expected for their age. Among responders the morning void was significantly larger than the following voids during the day, and among non-responders the fourth void was significantly larger than the previous voids in the day. Desmopressin treatment did not influence these volumes significantly. CONCLUSIONS: Short-term desmopressin treatment does not affect functional and mean bladder capacity; 24-h urine production was reduced significantly (P<0.01) during desmopressin treatment.

Intra-individual variability in nighttime urine production and functional bladder capacity estimated by home recordings in patients with nocturnal enuresis.

PURPOSE: We evaluated the intra-individual variability and reproducibility of nighttime urine production on wet nights and functional bladder capacity estimated by long-term home recordings of monosymptomatic nocturnal enuresis. In particular, the intention was to evaluate the validity of 1 versus 2 weeks of recording when estimating urine volume on wet nights and 1 versus 2 weekends of recording when estimating functional bladder capacity. MATERIALS AND METHODS: We analyzed 120, 2-week home recordings of nighttime urine volume from patients with monosymptomatic nocturnal enuresis 6 to 16 years old (mean age 9.1) with at least 3 wet nights per week. Most patients were nonresponders or partial responders to desmopressin. Nighttime urine volume was estimated by weighing diapers before and after sleep, and measuring morning urine volume. Of the home recordings 62 included frequency volume charts for 2 weekends, which were evaluated for functional bladder capacity defined as the largest voided volume observed. RESULTS: No significant overall week-to-week differences were observed in average urine volume on wet nights and functional bladder capacity. There was a large intra-individual variability in all measured variables, which was most pronounced for functional bladder capacity and least pronounced for urine volume on wet nights. With regard to repeatability, the limits of agreement of urine volume on wet nights were -32% and 36% (95% confidence interval) as opposed to -54% and 48% for functional bladder capacity. CONCLUSIONS: In this study intra-individual week-to-week estimates of average urine volume on wet nights demonstrated acceptable variability and repeatability in contrast to functional bladder capacity. A reliable estimate of urine volume on wet nights could be obtained by 7 nights of home recording, whereas 4 days of daytime recording were necessary when estimating functional bladder capacity. Similar studies of patients who respond to desmopressin are needed.

Ocular fluorescein kinetics before and after vitrectomy on swine.

PURPOSE: To study the quantitative effects of vitrectomy on fluorescein transport kinetics across the ocular barriers. METHODS: Thirty-six domestic swine were used in this study. Twenty anesthetized swine were given a standardized fluorescein intravenous injection immediately after unilateral vitrectomy. This was followed by one single central sample aspiration from the vitreous and the anterior chamber of both eyes in individual animals at increasing intervals up to 24 h after the injection. Fluorescein concentrations in the samples were determined by high-pressure liquid chromatography (HPLC). Eight swine underwent unilateral vitrectomy followed by anterior chamber and vitreous fluorophotometry on both eyes 1 month later. The fluorescein concentrations determined using this method were followed for 24 h. Similar examinations were performed in a control group of eight swine that did not undergo vitrectomy. Anterior chamber, vitreous, and plasma fluorescein concentration/time courses were analyzed kinetically by iterative nonlinear regression analysis. RESULTS: The barrier surrounding the anterior chamber of the eye was immediately impaired after vitrectomy, as evidenced by an increased area under the fluorescein concentration versus time curve, but the transport kinetics were restored within 1 month after surgery. The blood-retinal barrier was, however, persistently altered following vitrectomy. Transport rate and extent of drug penetration into the vitreous were increased, while drug elimination from the vitreous remained unchanged. CONCLUSION: Vitrectomy led to persistent kinetic fluorescein transport changes in the blood-retinal barrier resulting in faster and increased drug penetration to the vitreous, whereas similar alterations in the anterior chamber barrier transport were only transitory.