RESUMO
Serpentine soils represent stressful habitats where plants have to cope with heavy metals, moisture limitation and low nutrient availability. We propose that facilitation is an important mechanism structuring plant communities under such stressful conditions. Facilitation has been shown to generate the spatial association of species, forming discrete vegetation patches of phylogenetically distant species. We measured these spatial and phylogenetic signatures left by facilitation in a serpentine plant community of central Cuba. Our results show that seedlings preferentially grow under plants of different species, and that adults are significantly aggregated into vegetation patches. In these patches, adults tend to co-occur with distant relatives, ultimately forming phylogenetically diverse neighbourhoods. We discuss possible mechanisms explaining how species adapted to serpentine areas may be acting as nurses, reducing the stressful conditions for the establishment of other species.
Assuntos
Plantas , Solo , Biodiversidade , Cuba , Filogenia , Poluentes do SoloRESUMO
BACKGROUND: Few studies that have assessed the effect of abbreviated oral N-acetylcysteine (NAC) regimens in radiocontrast-induced nephropathy (RCIN) yield mixed results. OBJECTIVE: To evaluate the renoprotective effect of high periprocedural oral doses (HPOD) of NAC in patients with chronic renal impairment undergoing a same-day angiography. METHODS: Sixty one patients with renal impaired function scheduled to undergo a same-day angiography were randomly assigned to NAC 1200 mg orally 3 hours before and 3 after the procedure, or a placebo. All patients received 0.9% saline intravenous. RCIN was defined as an increase in SCC > 0.5 mg/dl 48 hours after the procedure. RESULTS: The mean baseline SCC for all patients was 1.44 +/- 0.42 mg/dl. A significant difference in SCC change at 48 hours after the angiography was found (-0.07 mg/dl NAC, 0.09 mg/dl placebo, P = 0.04). RCIN occurred in 1 (3%) patient of NAC group and in 2 (7.1%) patients of placebo group (P = 0.59). Adverse effects were similar in both groups. CONCLUSIONS: In patients with mild renal impairment patients undergoing angiographic procedures, HPOD of NAC were more effective than placebo in preventing SCC change 48 hours. A non significant benefit in RCIN incidence was found.(AU)
Los escasos estudios que han evaluados los efectos de regimenes abreviados de Nacetilcisteína (NAC) oral en la nefropatía por contraste (NC) han encontrado resultados contrapuestos. OBJETIVO: Evaluar el efecto renoprotector de altas dosis orales periprocedimiento (ADOP) de NAC en pacientes con insuficiencia renal con angiografía programada el mismo día. MATERIAL y METODOS: Sesenta y un pacientes con insuficiencia renal y angiografía programada para el mismo día fueron asignados aleatoriamente a 1200 mg de NAC 3 horas previas y 3 horas posteriores al cateterismo o un placebo. Todos los pacientes recibieron hidratación endovenosa con solución salina al 0.9%. La NC se definió como el aumento en la creatinina sérica (CS) > 0.5 mg/dl a las 48 horas del procedimiento. RESULTADOS: La CS media en todos los pacientes fue 1.44: t 0.42 mg/dl. Se encontró una diferencia significativa entre ambos grupos en el cambio de CS a las 48 horas de la angiografía (-0.07 mg/dl NAC, 0.09 mg/dl placebo, P=0.04). La NC se presentó en 1 (3%) paciente del grupo NAC y en 2 (7.1 %) pacientes del grupo placebo (P=0.59). Los efectos adversos fueron similares en ambos grupos. CONCLUSION: En pacientes con insuficiencia renal leve sometidos a angiografía en el mismo día, las ADOP de NAC fueron más efectivas que el placebo en la prevención del cambio de CS a las 48 horas del procedimiento. Se encontró un beneficio no significativo en la incidencia de NC.(AU)
Assuntos
Idoso , Feminino , Humanos , Masculino , Acetilcisteína/uso terapêutico , Antioxidantes/uso terapêutico , Meios de Contraste/efeitos adversos , Falência Renal Crônica/prevenção & controle , Acetilcisteína/administração & dosagem , Administração Oral , Angiografia , Antioxidantes/administração & dosagem , Método Duplo-Cego , Falência Renal Crônica/induzido quimicamente , Estudos ProspectivosRESUMO
BACKGROUND: Few studies that have assessed the effect of abbreviated oral N-acetylcysteine (NAC) regimens in radiocontrast-induced nephropathy (RCIN) yield mixed results. OBJECTIVE: To evaluate the renoprotective effect of high periprocedural oral doses (HPOD) of NAC in patients with chronic renal impairment undergoing a same-day angiography. METHODS: Sixty one patients with renal impaired function scheduled to undergo a same-day angiography were randomly assigned to NAC 1200 mg orally 3 hours before and 3 after the procedure, or a placebo. All patients received 0.9% saline intravenous. RCIN was defined as an increase in SCC > 0.5 mg/dl 48 hours after the procedure. RESULTS: The mean baseline SCC for all patients was 1.44 +/- 0.42 mg/dl. A significant difference in SCC change at 48 hours after the angiography was found (-0.07 mg/dl NAC, 0.09 mg/dl placebo, P = 0.04). RCIN occurred in 1 (3%) patient of NAC group and in 2 (7.1%) patients of placebo group (P = 0.59). Adverse effects were similar in both groups. CONCLUSIONS: In patients with mild renal impairment patients undergoing angiographic procedures, HPOD of NAC were more effective than placebo in preventing SCC change 48 hours. A non significant benefit in RCIN incidence was found.
Los escasos estudios que han evaluados los efectos de regimenes abreviados de Nacetilcisteína (NAC) oral en la nefropatía por contraste (NC) han encontrado resultados contrapuestos. OBJETIVO: Evaluar el efecto renoprotector de altas dosis orales periprocedimiento (ADOP) de NAC en pacientes con insuficiencia renal con angiografía programada el mismo día. MATERIAL y METODOS: Sesenta y un pacientes con insuficiencia renal y angiografía programada para el mismo día fueron asignados aleatoriamente a 1200 mg de NAC 3 horas previas y 3 horas posteriores al cateterismo o un placebo. Todos los pacientes recibieron hidratación endovenosa con solución salina al 0.9%. La NC se definió como el aumento en la creatinina sérica (CS) > 0.5 mg/dl a las 48 horas del procedimiento. RESULTADOS: La CS media en todos los pacientes fue 1.44: t 0.42 mg/dl. Se encontró una diferencia significativa entre ambos grupos en el cambio de CS a las 48 horas de la angiografía (-0.07 mg/dl NAC, 0.09 mg/dl placebo, P=0.04). La NC se presentó en 1 (3%) paciente del grupo NAC y en 2 (7.1 %) pacientes del grupo placebo (P=0.59). Los efectos adversos fueron similares en ambos grupos. CONCLUSION: En pacientes con insuficiencia renal leve sometidos a angiografía en el mismo día, las ADOP de NAC fueron más efectivas que el placebo en la prevención del cambio de CS a las 48 horas del procedimiento. Se encontró un beneficio no significativo en la incidencia de NC.
Assuntos
Idoso , Feminino , Humanos , Masculino , Acetilcisteína/uso terapêutico , Antioxidantes/uso terapêutico , Falência Renal Crônica/prevenção & controle , Meios de Contraste/efeitos adversos , Administração Oral , Angiografia , Acetilcisteína/administração & dosagem , Antioxidantes/administração & dosagem , Método Duplo-Cego , Falência Renal Crônica/induzido quimicamente , Estudos ProspectivosRESUMO
A comparative study between an unburned evergreen sclerophyllousvegetation located in south-central Mexico under a wet-summer climate,with mediterranean regions was conducted in order to re-analyzevegetation and plant characters claimed to converge under mediterraneanclimates. The comparison considered floristic composition,plant-community structure, and plant characters as adaptations tomediterranean climates and analyzed them by means of a correspondenceanalysis, considering a tropical spiny shrubland as the external group.We made a species register of the number of species that resproutedafter a fire occurred in 1995 and a distribution map of the evergreensclerophyllous vegetation in Mexico (mexical) under nonmediterraneanclimates.The Tehuacán mexical does not differ from the evergreensclerophyllous areas of Chile, California, Australia, and theMediterranean Basin, according to a correspondence analysis, whichordinated the Tehuacán mexical closer to the mediterranean areasthan to the external group.All the vegetation and floristic characteristics of the mexical, aswell as its distribution along the rain-shadowed mountain parts ofMexico, support its origin in the Madrean-Tethyan hypothesis of Axelrod.Therefore, these results allow to expand the convergence paradigm of thechaparral under an integrative view, in which a general trend to ariditymight explain floristic and adaptive patterns detected in theseenvironments.