Putrescine differently influences the effect of salt stress on polyamine metabolism and ethylene synthesis in rice cultivars differing in salt resistance

Effects of salt stress on polyamine metabolism and ethylene production were examined in two rice (Oryza sativa L.) cultivars [I Kong Pao (IKP), salt sensitive; and Pokkali, salt resistant] grown for 5 d and 12 d in nutrient solution in the presence or absence of putrescine (1 mM) and 0, 50, and 100 mM NaCl. The salt-sensitive (IKP) and salt-resistant (Pokkali) cultivars differ not only in their mean levels of putrescine, but also in the physiological functions assumed by this molecule in stressed tissues. Salt stress increased the proportion of conjugated putrescine in salt-resistant Pokkali and decreased it in the salt-sensitive IKP, suggesting a possible protective function in response to NaCl. Activities of the enzymes ornithine decarboxylase (ODC; EC 4.1.1.17) and arginine decarboxylase (ADC; EC 4.1.1.19) involved in putrescine synthesis were higher in salt-resistant Pokkali than in salt-sensitive IKP. Both enzymes were involved in the response to salt stress. Salt stress also increased diamine oxidase (DAO; 1.4.3.6) and polyamine oxidase (PAO EC 1.5.3.11) activities in the roots of salt-resistant Pokkali and in the shoots of salt-sensitive IKP. Gene expression followed by reverse transcription-PCR suggested that putrescine could have a post-translational impact on genes coding for ADC (ADCa) and ODC (ODCa and ODCb) but could induce a transcriptional activation of genes coding for PAO (PAOb) mainly in the shoot of salt-stressed plants. The salt-resistant cultivar Pokkali produced higher amounts of ethylene than the salt-sensitive cultivar IKP, and exogenous putrescine increased ethylene synthesis in both cultivars, suggesting no direct antagonism between polyamine and ethylene pathways in rice

Disturbance of Glucose Homeostasis After Pediatric Cardiac Surgery

This study aimed to evaluate the time course of perioperative blood glucose levels of children undergoing cardiac surgery for congenital heart disease in relation to endogenous stress hormones, inflammatory mediators, and exogenous factors such as caloric intake and glucocorticoid use. The study prospectively included 49 children undergoing cardiac surgery. Blood glucose levels, hormonal alterations, and inflammatory responses were investigated before and at the end of surgery, then 12 and 24 h afterward. In general, blood glucose levels were highest at the end of surgery. Hyperglycemia, defined as a glucose level higher than 8.3 mmol/l (>150 mg/dl) was present in 52% of the children at the end of surgery. Spontaneous normalization of blood glucose occurred in 94% of the children within 24 h. During surgery, glucocorticoids were administered to 65% of the children, and this was the main factor associated with hyperglycemia at the end of surgery (determined by univariate analysis of variance). Hyperglycemia disappeared spontaneously without insulin therapy after 12–24 h for the majority of the children. Postoperative morbidity was low in the study group, so the presumed positive effects of glucocorticoids seemed to outweigh the adverse effects of iatrogenic hyperglycemia

Impairment of Rat Fetal Beta-Cell Development by Maternal Exposure to Dexamethasone during Different Time-Windows

Glucocorticoids (GCs) take part in the direct control of cell lineage during the late phase of pancreas development when endocrine and exocrine cell differentiation occurs. However, other tissues such as the vasculature exert a critical role before that phase. This study aims to investigate the consequences of overexposure to exogenous glucocorticoids during different time-windows of gestation for the development of the fetal endocrine pancreas