F Roze | Search PubMed

PubMed1999

[In Process Citation]

The soil dynamics of old-fields, characterized by the early establishment of broom (Cytisus scoparius L.), is analysed in the Breton bocage. The role of former land use practices is estimated by comparing two similar plant successions, post cultivation and post pasture. Different variables (organic matter, mineral N content, microbial biomass, total microbial activity and mineralization) are measured within the soil layer disturbed by farming (between -5 and -25 cm). One year after abandonment, the parameters taken into account show similar values for both series. After 8 years, in broom thickets, the two soil series are characterized by an increase in microbial activity, organic matter and mineral N contents. However, the post cultivation thicket differed by higher N content and mineralization rate than the post pasture thicket, but also by a smaller microbial biomass. It appears that, if the development of similar vegetational communities promotes the same kind of soil dynamics, the former land use practices significantly modify this evolution, for at least the first 8 years following abandonment.

Journal Article↗

PubMed1990

[Consequences of hyperglycemia on glucose and nitrogen metabolism in liver cirrhosis. A study using a hyperglycemic clamp].

To study the consequences of hyperglycemia on glucose and nitrogen metabolism in cirrhosis, an hyperglycemic clamp was performed in 5 cirrhotic patients and 5 normal controls during two subsequent periods of 90 min, at 7.78 and then at 13.89 mmol/l. In the first period, glucose infusion and metabolic clearance rates were decreased in cirrhotics vs controls (p less than 0.05). In the second period, this difference between the two groups disappeared because of a more important enhancement in cirrhotics. Baseline plasma C peptide levels and those during hyperglycemia were the same during hyperglycemia in both groups, but plasma insulin level rose more in cirrhotics (p less than 0.05). Baseline insulin secretion following IV glucagon was reduced in cirrhotics vs controls (p less than 0.05), but became normal in the hyperglycemic state. Plasma glucagon levels were enhanced at all times in cirrhotics vs controls (p less than 0.01), but dropped more in cirrhotics vs controls (p less than 0.05). Insulin responsiveness, defined as the "glucose consumption: plasma insulin concentration" ratio was reduced in cirrhotics at 7.78 mmol/l (p less than 0.01), but was the same in both groups at 13.80 mmol/l because of a more important enhancement in cirrhotics, reflecting an improvement of insulin action probably at the post-receptor level and of non-insulin-mediated glucose transport. Hyperglycemia induced a drop in plasma concentration and muscular release of all aminoacids, excepted alanine, between the basal state and the end of the study. Aminoacid concentration rose only in cirrhotics, without any change in muscular output. In the same time, blood ammonia level rose only in cirrhotics, without reduction of muscular uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗