The impact of agricultural Best Management Practices on water quality in a North German lowland catchment.

Research on water quality degradation caused by point and diffuse source pollution plays an important role in protecting the environment sustainably. Implementation of Best Management Practices (BMPs) is a conventional approach for controlling and mitigating pollution from diffuse sources. The objectives of this study were to assess the long-term impact of point and diffuse source pollution on sediment and nutrient load in a lowland catchment using the ecohydrological model Soil and Water Assessment Tool (SWAT) and to evaluate the cost and effectiveness of BMPs for water quality improvement in the entire catchment. The study area, Kielstau catchment, is located in the North German lowlands. The water quality is not only influenced by the predominating agricultural land use in the catchment as cropland and pasture, but also by six municipal wastewater treatment plants. Diffuse entries as well as punctual entries from the wastewater treatment plants are implemented in the model set-up. Results from model simulations indicated that the SWAT model performed satisfactorily in simulating flow, sediment, and nutrient load in a daily time step. Two approaches to structural and nonstructural BMPs have been recommended in relation to cost and effectiveness of BMPs in this study. These BMPs include extensive land use management, grazing management practice, field buffer strip, and nutrient management plan. The results showed that BMPs would reduce fairly the average annual load for nitrate and total nitrogen by 8.6% to 20.5%. However, the implementation of BMPs does not have much impact on reduction in the average annual load of sediment and total phosphorus at the main catchment outlet. The results obtained by implementing those BMPs ranged from 0.8% to 4.9% and from 1.1% to 5.3% for sediment and total phosphorus load reduction, respectively. This study also reveals that reduction only in one type of BMP did not achieve the target value for water quality according to the European Water Framework Directive. The combination of BMPs improved considerably water quality in the Kielstau catchment, achieving a 53.9% and a 46.7% load reduction in nitrate and total nitrogen load, respectively, with annual implementation cost of 93,000 Euro.

Immunolocalization of aromatase and estrogen receptors in ram Leydig cells.

A microsomal enzyme, the cytochrome P450 aromatase, performs aromatization of androgens to estrogens. The site of this action has been detected by immunohistochemistry. Sexually immature and mature rams were the donors of testes. Leydig cells were isolated and cultured during 24 h or whole testes were used for cryosections. Both, cultured cells and sections were analysed immunocyto- or immunohistochemically. In adult ram, Leydig cells were the main site of an active aromatase as well as estrogen receptors. While in immature ram very weak or no activity was observed. Therefore, the localizations of immunoreactive aromatase and estrogen synthesis have been found as age-dependent.

Are ovine Leydig cells able to aromatize androgens?

The conversion of testosterone into oestradiol by ovine Leydig cells cultured in vitro was studied using the non-steroidal aromatase inhibitor CGS 16949A. Additionally, aromatase activity was detected by immunohistochemical staining of cultured Leydig cells or cryosections. The cells were obtained from testes of Polish Mountain rams 5-6 months old (immature) or 12-15 months old (mature). Leydig cells were cultured alone (controls) or incubated for 6 h in the presence of testosterone. Aromatase inhibitor was then added to the cultures which were incubated for a further 18 h. After a 24-h incubation period, testosterone and oestradiol secretion were determined by testing the culture medium using radioimmunological methods. The addition of testosterone to the culture medium enhanced oestradiol synthesis, suggesting that exogenous testosterone could also be aromatized to oestradiol by ovine Leydig cells in vitro. In the presence of CGS 16949A, the conversion of testosterone to oestradiol was significantly suppressed in a dose-dependent manner. All Leydig cells obtained from testes of mature rams and stained immunohistochemically were positive for aromatase, whereas Leydig cells from immature males were negative. The localization of immunoreactive aromatase appeared to be dependent on the age of the donor ram. It is suggested therefore, that mature Leydig cells in the ram are not only the site for testosterone synthesis, they are also capable of converting androgens into oestrogens.

Successful hemostasis during a major orthopedic operation by using recombinant activated factor VII in a patient with severe hemophilia A and a potent inhibitor.

The treatment of bleeding episodes and the provision of perioperative hemostasis in patients with hemophilia in whom coagulation factor inhibitors have developed are a major therapeutic challenge because ordinary replacement therapy is usually ineffective. Herein we report the use of recombinant activated factor VII (rFVIIa) in providing successful hemostasis in a patient with hemophilia A and a high-titer inhibitor to factor VIII during a major orthopedic operation. rFVIIa (102 micrograms/kg) was administered intravenously every 2 to 3 hours for a total of 9 days. No excessive bleeding occurred intraoperatively or postoperatively, and no adverse effects attributable to rFVIIa were observed. This surgical procedure probably represented a greater hemostatic challenge than any previously reported operation in which rFVIIa was used. Thus, this article adds considerably to the growing body of literature that suggests the safety and efficacy of rFVIIa in providing perioperative hemostasis and treating severe bleeding episodes in patients with hemophilia and inhibitors refractory to other treatment modalities.