Intraoperative dextrose rate during exploratory laparotomies in neonates and the incidence of postoperative hyperglycemia: A retrospective observational study.

INTRODUCTION: Compared with the older pediatric population, neonates have greater perioperative morbidity and mortality. Difficulty with glucose regulation may be a contributing modifiable risk factor during perioperative anesthetic management. To mitigate the risk of hyperglycemia in neonates, some providers empirically halve the preoperative rate of dextrose-containing infusions during surgery. AIM: To assess the association between halving the preoperative maintenance dextrose rate and postoperative euglycemia in neonatal intensive care unit patients undergoing exploratory laparotomies. METHODS: Neonatal intensive care unit patients who underwent exploratory laparotomy under general anesthesia from 1/1/2014 to 11/21/2019 were included in this analysis. Hyperglycemia and hypoglycemia were defined as >150 mg/dL and <46 mg/dL. A calculated dextrose ratio was utilized to categorize patients into full and half intraoperative dextrose rate cohorts. Univariate analyses were performed with Fisher's exact test, the Wilcoxon rank sum test, or Spearman's correlation. Multivariable analyses with regression models were conducted after graphical evaluation of a predetermined set of independent variables. RESULTS: 107 patients were included in the full dextrose rate cohort and 96 patients in the half dextrose rate cohort with postoperative hyperglycemia occurring in 47 and 28 patients, respectively. On univariate analysis, halving the preoperative dextrose rate was associated with decreased postoperative hyperglycemia (odds ratio: 0.53; 95% CI: 0.28-0.98, P = 0.041). This association continued in the regression model (adjusted odds ratio: 0.49; 95% CI: 0.25-0.80, P = 0.008) after controlling for preoperative dextrose rate, preoperative serum glucose, preoperative pH, surgical duration, postmenstrual age at surgery, and the presence of necrotizing enterocolitis. Only one patient was hypoglycemic postoperatively, and they were in the full dextrose cohort. CONCLUSION: Halving of preoperative dextrose rates intraoperatively during exploratory laparotomy in neonatal intensive care unit patients was associated with a decreased risk of postoperative hyperglycemia without substantially increasing the occurrence of postoperative hypoglycemia. The practice of halving preoperative dextrose rates may be an effective empirical approach for intraoperative glucose management in the high-risk neonatal population when blood glucose monitoring is challenging.

The mechanism of transcriptional activation by the topologically DNA-linked sliding clamp of bacteriophage T4.

Three viral proteins participate directly in transcription of bacteriophage T4 late genes: the sigma-family protein gp55 provides promoter recognition, gp33 is the co-activator, and gp45 is the activator of transcription; gp33 also represses transcription in the absence of gp45. Transcriptional activation by gp45, the toroidal sliding clamp of the T4 DNA polymerase holoenzyme, requires assembly at primer-template junctions by its clamp loader. The mechanism of transcriptional activation has been analyzed by examining rates of formation of open promoter complexes. The basal gp55-RNA polymerase holoenzyme is only weakly held in its initially formed closed promoter complex, which subsequently opens very slowly. Activation ( approximately 320-fold in this work) increases affinity in the closed complex and accelerates promoter opening. Promoter opening by gp55 is also thermo-irreversible: the T4 late promoter does not open at 0 degrees C, but once opened at 30 degrees C remains open upon shift to the lower temperature. At a hybrid promoter for sigma(70) and gp55-holoenzymes, only gp55 confers thermo-irreversibility of promoter opening. Interaction of gp45 with a C-terminal epitope of gp33 is essential for the co-activator function of gp33.

General anesthetic actions on GABA(A) receptors.

General anesthetic drugs interact with many receptors in the nervous system, but only a handful of these interactions are critical for producing anesthesia. Over the last 20 years, neuropharmacologists have revealed that one of the most important target sites for general anesthetics is the GABA(A) receptor. In this review we will discuss what is known about anesthetic - GABA(A) receptor interactions.