Recherches sur les écosystemes des réserves biologiques de la Forêt de Fontainebleau. VII - Structure et fonctions des peuplements de houx (Ilex aquifolium L.)

Holly bushes form an important structural unit in some natural reserves of the Fontainebleau forest (60 km S.E. of Paris). Due to the high stem density of the holly, its great basal area and the longevity of its leaves (about two years), the biomass and the global productivity of the mature beech-oak forest are appreciably increased. This additional production brings about a large immobilisation and important turn-over of nutrients. Holly plays an important role as potassium accumulator and magnesium cycle accelerator. The leaf litter, falling alternately from holly and trees, is appreciably increased in volume and its mineral and nitrogen contents are enriched. During the first months following leaf drop, decomposition of the holly litter is very rapid. The actual evolution of holly populations tend to be extended by the peripheral formation of suckers and by seedlings. Under the bushes, deep shade and thick litter accumulation inhibit any regeneration. The progressive substitution of old oaks by beeches is unfavorable to holly. The presence of holly stands could represent a preterminal stage of this forest successio

Recherches sur les écosystèmes des réserves biologiques de la forêt de Fontainebleau. VII. Structure et fonctions des peuplements de houx (Ilex aquifolium L.)

Holly bushes form an important structural unit in some natural reserves of the Fontainebleau forest (60 km S.E. of Paris). Due to the high stem density of the holly, its great basal area and the longevity of its leaves (about two years), the biomass and the global productivity of the mature beech-oak forest are appreciably increased. This additional production brings about a large immobilisation and important turn-over of nutrients. Holly plays an important role as potassium accumulator and magnesium cycle accelerator. The leaf litter, falling alternately from holly and trees, is appreciably increased in volume and its mineral and nitrogen contents are enriched. During the first months following leaf drop, decomposition of the holly litter is very rapid. The actual evolution of holly populations tend to be extended by the peripheral formation of suckers and by seedlings. Under the bushes, deep shade and thick litter accumulation inhibit any regeneration. The progressive substitution of old oaks by beeches is unfavorable to holly. The presence of holly stands could represent a preterminal stage of this forest succession.Clabault G., Lemée G., Bichaut N., Legay B., Pontailler J.Y. Recherches sur les écosystèmes des réserves biologiques de la forêt de Fontainebleau. VII. Structure et fonctions des peuplements de houx (Ilex aquifolium L.). In: Revue d'Écologie (La Terre et La Vie), tome 34, n°3, 1980. pp. 317-334

Respective effects of end-expiratory and end-inspiratory pressures on alveolar recruitment in acute lung injury

Objective. A low tidal volume can induce alveolar derecruitment in patients with acute lung injury. This study was undertaken to evaluate whether this resulted mainly from the decrease in tidal volume per se or from the reduction in end-inspiratory plateau pressure and whether there is any benefit in raising the level of positive end-expiratory pressure (PEEP) while plateau pressure is kept constant. Design: Prospective crossover study. Setting: Medical intensive care unit of a university teaching hospital. Patients: Fifteen adult patients ventilated for acute lung injury (PaO2/FIO2, 158 +/- 34 mm Hg; lung injury score, 2.7 +/- 0.6). Interventions: Three combinations were tested: PEEP at the lower inflection point with 6 mL/kg tidal volume, PEEP at the lower inflection point with 10 mL/kg tidal volume, and high PEEP with tidal volume at 6 mL/kg, keeping the plateau pressure similar to the preceding condition. Measurements and Main Results: Pressure-volume curves at zero PEEP and at set PEEP were recorded, and recruitment was calculated as the volume difference between both curves for pressures ranging from 15 to 30 cm H2O. Arterial blood gases were measured for all patients. For a similar PEEP at the lower inflection point (10 +/- 3 cm H2O), tidal volume reduction (10 to 6 mL/kg) led to a significant derecruitment. A low tidal volume (6 mL/kg) with high PEEP (14 +/- 3 cm H2O), however, induced a significantly greater recruitment and a higher PaO2 than the two other strategies. Conclusion. At a given plateau pressure (i.e., similar end-inspiratory distension), lowering tidal volume and increasing PEEP increase recruitment and PaO2

Antiproliferative, antiandrogenic and cytotoxic effects of novel caffeic acid derivatives in LNCaP human androgen-dependent prostate cancer cells.

International audienceCaffeic acid and its naturally occurring derivative caffeic acid phenethyl ester (CAPE) have antiproliferative and cytotoxic properties in a variety of cancer cell lines without displaying significant toxicity toward healthy cells, and are considered to be potential anticancer agents. However, little is known about their effects on prostate cancer cells. We synthesized and evaluated the effects of caffeic acid, CAPE (2) and 18 synthetic derivatives on cell viability and androgen-dependent cell proliferation, subcellular localisation and expression of androgen receptor (AR) and secretion of prostate-specific antigen (PSA) in LNCaP human hormone-dependent prostate cancer cells. Several synthetic derivatives of CAPE were strong, concentration-dependent cytotoxic agents in LNCaP cells with IC50 values in the 6.8-26.6 μM range, potencies that were up to five-fold greater than that of CAPE (33.7±4.0 μM). A number of caffeic acid derivatives were inhibitors of androgen-stimulated LNCaP cell proliferation with concomitant inhibition of DHT-stimulated PSA secretion. Compound 24 was the most cytotoxic and antiproliferative caffeic acid derivative (IC50 values of 6.8±0.3 and 2.4±0.8 μM, respectively) inhibiting DHT-stimulated cell proliferation and PSA secretion statistically significantly at concentrations as low as 0.3 μM. Exposure to DHT increased cytoplasmic and nuclear AR levels and co-treatment with increasing concentrations of compound 24 or CAPE (2), notably, further increased these levels. In conclusion, a number of synthetic derivatives of caffeic acid are potent inhibitors of androgen-dependent prostate cancer cell proliferation and viability, acting, at least in part, via an antiandrogenic mechanism that involves increased nuclear accumulation of (presumably inactive) AR

Further progress towards a catalogue of all Arabidopsis genes: analysis of a set of 5000 non-redundant ESTs

International audienc