Nitrogen starvation for lipid accumulation in the microalga species Desmodesmus sp.

Recently, to obtain lipids from microalgae has been the object of extensive research, since it is viewed as a promising feedstock for biodiesel production, especially when compared with crops such as soybean and sunflower, in terms of theoretical performance. The reduction of nutrient availability in culture media, especially nitrogen, stresses the microorganisms and affects cell growth, thus inducing lipid accumulation. This is an interesting step in biodiesel feedstock obtention from microalgae and should be better understood. In this study, four levels of nitrogen concentration in the BG-11 culture medium were evaluated in the growth of the chlorophycean microalga Desmodesmus sp. Both cell growth and lipid content were monitored over 7 days of cultivation, which yielded a final cell density of 33 × 10(6) cells mL(-1) with an initial NaNO3 concentration of 750 mg L(-1) in the medium and a maximum lipid content of 23 % with total nitrogen starvation. It was observed that the microalgae presented high lipid accumulation in the fourth day of cultivation with nitrogen starvation, although with moderate cell growth.

Influence of mycophenolic acid and FK-506 on human platelet activation in vitro.

BACKGROUND/AIM: FK-506 (FK) and mycophenolic acid (MPA) are immunosuppressive agents used in kidney transplant recipients. Their effect on posttransplant thromboembolic complications is either controversial (FK) or has not been described (MPA). Thromboembolic events are among the consequences of platelet hyperaggregability which can be identified by measuring platelet aggregation. The aim of this study was to evaluate the in vitro effects of MPA and FK upon platelet activation in healthy subjects. METHODS: Platelet-rich plasma from healthy volunteers (n = 18) was incubated with FK (70 ng/ml), FK vehicle, and MPA (30 microg/ml) before platelet aggregation was induced by the platelet agonists adenosine diphosphate (2 and 5 microM) and collagen 0.5 and 1.0 microg/ml). Aggregation was measured by recording the optical density. RESULTS: MPA resulted in a significant decrease in the platelet response to collagen (1.0 microg/ml) in platelet-rich plasma, whereas FK significantly increased platelet aggregation in response to collagen (0.5 microg/ml). The vehicle of FK had no influence on platelet aggregation with either agonist. CONCLUSIONS: The decreased platelet-activating response following preincubation with MPA may favor its use in kidney transplant recipients to reduce thromboembolic events. The FK-induced enhancement of platelet aggregation shown in vitro may lead to thromboembolic complications in transplant recipients.

Long-term clinical course and histopathologic scoring in acute crescentic glomerulonephritis.

If nontreated or misdiagnosed, acute crescentic glomerulonephritis, clinically defined as rapidly progressive glomerulonephritis (RPGN), may led to end-stage renal failure (ESRD) within a short time. Histologically, it is characterized by accumulation of inflammatory cells in combination with proliferation of epithelial cells in the glomerulus. According to the proposed immunopathogenic classification by Couser (7), predominantly the immunopathogenic type III without immune deposits often represents the renal manifestation of a systemic vasculitic disease, for example, polyarteriitis or Wegener's granulomatosis. Having investigated 75 patients with acute crescentic glomerulonephritis in respect to their long-term results, we conclude that an early histopathologic diagnosis by using an activity and chronicity score system may not only be a predictor for renal prognosis but also be a valid supposition for differentiated immunosuppressive therapy in supplement to the clinical data on renal function. A therapeutic advantage of a plasmapheresis therapy additionally to the immunosuppressive therapy could not be proven.