Screening for hypoglycemia at the bedside in the neonatal intensive care unit (NICU) with the Abbott PCx glucose meter

BACKGROUND: Point of care (POC) glucose meters are routinely used as a screening tool for hypoglycemia in a neonatal setting. Glucose meters however, lack the same accuracy as laboratory instruments for glucose measurement. In this study we investigated potential reasons for this inaccuracy and established a cut off value for confirmatory testing. METHODS: In this prospective study, all patients in the neonatal intensive care unit who had a plasma glucose test ordered were eligible to participate. Demographic information, sample collection information (nine variables) and a recent hematocrit value were recorded for each sample. Glucose measurements were taken at the bedside on the glucose meter (RN PCx) as well as in the laboratory on both the glucose meter (LAB PCx) and the laboratory analyzer (PG). Data were analyzed by simple and mixed-effects regression analysis and by analysis of a receiver operator characteristics (ROC) curve. RESULTS: There were 475 samples analyzed from 132 patients. RN PCx values were higher than PG values (mean = 4.9%), while LAB PCx results were lower (mean = -5.2%) than PG values. Only 31% of the difference between RN PCx – PG and 46% of the difference for LAB PCx – PG could be accounted for by the variables tested. The largest proportion of variance between PCx and PG measurements was explained by hematocrit (about 30%) with a greater effect seen at glucose concentrations ≤4.0 mmol/L (≤72 mg/dL)(48% and 40% for RN PCx and LAB PCx, respectively). The ROC analysis showed that for detection of all cases of hypoglycemia (PG < 2.6 mmol/L)(PG < 47 mg/dL) the PCx screening cut off value would need to be set at 3.8 mmol/L (68 mg/dL) requiring 20% of all samples to have confirmatory analysis by the laboratory method. CONCLUSION: The large difference between glucose results obtained by PCx glucose meter compared to the laboratory analyzer can be explained in part by hematocrit and low glucose concentration. These results emphasize that the glucose meter is useful only as a screening device for neonatal hypoglycemia and that a screening cut off value must be established

Synapsin II Is Involved in the Molecular Pathway of Lithium Treatment in Bipolar Disorder

Bipolar disorder (BD) is a debilitating psychiatric condition with a prevalence of 1–2% in the general population that is characterized by severe episodic shifts in mood ranging from depressive to manic episodes. One of the most common treatments is lithium (Li), with successful response in 30–60% of patients. Synapsin II (SYN2) is a neuronal phosphoprotein that we have previously identified as a possible candidate gene for the etiology of BD and/or response to Li treatment in a genome-wide linkage study focusing on BD patients characterized for excellent response to Li prophylaxis. In the present study we investigated the role of this gene in BD, particularly as it pertains to Li treatment. We investigated the effect of lithium treatment on the expression of SYN2 in lymphoblastoid cell lines from patients characterized as excellent Li-responders, non-responders, as well as non-psychiatric controls. Finally, we sought to determine if Li has a cell-type-specific effect on gene expression in neuronal-derived cell lines. In both in vitro models, we found SYN2 to be modulated by the presence of Li. By focusing on Li-responsive BD we have identified a potential mechanism for Li response in some patients

Drug-induced endocytosis of neonatal erythrocytes

The erythrocytes of the newborn infant have many properties that distinguish them from those of adults, and their membranes are also different from those of adult erythrocytes. We compared the ability of adult and neonatal RBCs to undergo endocytosis on exposure to drugs. Using a quantitative method, we showed that neonatal erythrocytes undergo a greater degree of endocytosis than do adult RBCs in response to primaquine, vinblastine, and chlorpromazine, and are sensitive to lower concentrations of the drugs. Some forms of drug-induced endocytosis are red cell age-dependent; when RBCs were separated by density gradient centrifugation, the membranes of the younger, less dense populations of both the neonatal and adult RBCs were capable of more extensive internalization than those of the denser, older RBCs. Neonatal RBCs of a given density undergo more endocytosis than do adult RBCs of the same density, suggesting that the membrane of the neonatal RBC is less stable and capable of more of the reorganization reflected in endocytosis than is the adult RBC membrane.</jats:p

Drug-induced endocytosis of neonatal erythrocytes

Abstract The erythrocytes of the newborn infant have many properties that distinguish them from those of adults, and their membranes are also different from those of adult erythrocytes. We compared the ability of adult and neonatal RBCs to undergo endocytosis on exposure to drugs. Using a quantitative method, we showed that neonatal erythrocytes undergo a greater degree of endocytosis than do adult RBCs in response to primaquine, vinblastine, and chlorpromazine, and are sensitive to lower concentrations of the drugs. Some forms of drug-induced endocytosis are red cell age-dependent; when RBCs were separated by density gradient centrifugation, the membranes of the younger, less dense populations of both the neonatal and adult RBCs were capable of more extensive internalization than those of the denser, older RBCs. Neonatal RBCs of a given density undergo more endocytosis than do adult RBCs of the same density, suggesting that the membrane of the neonatal RBC is less stable and capable of more of the reorganization reflected in endocytosis than is the adult RBC membrane.</jats:p

Myosin in adult and neonatal human erythrocyte membranes

The heavy chain of myosin can be detected in human red cell membranes by immunoblot analysis with antiplatelet myosin antibodies. Neonatal red cell membranes have more immunoreactive myosin than adult membranes. Membranes from young adult red cells contain more immunoreactive myosin than membranes from old adult red cells. In contrast, young and old neonatal red cells have equivalent mounts of myosin. Erythrocyte myosin is present in a membrane fraction enriched in integral membrane proteins but is not found in cytoskeletal preparations.</jats:p

Myosin in adult and neonatal human erythrocyte membranes

Abstract The heavy chain of myosin can be detected in human red cell membranes by immunoblot analysis with antiplatelet myosin antibodies. Neonatal red cell membranes have more immunoreactive myosin than adult membranes. Membranes from young adult red cells contain more immunoreactive myosin than membranes from old adult red cells. In contrast, young and old neonatal red cells have equivalent mounts of myosin. Erythrocyte myosin is present in a membrane fraction enriched in integral membrane proteins but is not found in cytoskeletal preparations.</jats:p