DEXTROSE-, ADENOSINE- AND MAGNESIUM-INDUCED PROTECTIVE ACTIONS DURING ANOXIA AND REPERFUSION IN CANINE PURKINJE TISSUE

1. The effects of dextrose, magnesium (Mg) and adenosine on membrane potential and force of contraction were studied in driven and overdriven canine cardiac Purkinje tissue. 2. Dextrose (50 mmol/L) and adenosine (4–6 mmol/L) both showed protective action (the latter to a lesser extent) against simulated anoxia and reperfusion- induced arrhythmias, increased force of contraction transiently on reperfusion, and the former sustained the increase in force to a lower level as long as it was in the superfusing solution. 3. Dextrose (50 mmol/L) and Mg (5 mmol/L) restored overdrive- induced hyperpolarization during simulated anoxia. Adenosine was largely ineffective. 4. It was concluded that dextrose and adenosine (to a lesser extent) protect against arrhythmias by replenishing the critical intracellular pool of ATP which controls membrane transport of electrolytes such as K and Ca. Restoration of Na-K ATPase activity alone (as in the case of high Mg concentrations) is not sufficient to prevent arrhythmias.     

Adverse events associated with neonatal exchange transfusion in the 1990s

OBJECTIVE: To determine the rates of adverse events associated with neonatal exchange transfusions performed for hyperbilirubinemia. STUDY DESIGN: Retrospective chart review of 55 neonates who underwent 66 exchange transfusions at two perinatal centers in Cleveland between 1992 and 2002. Demographic data, causes of jaundice, details of exchange method, and adverse events occurring within one week of exchange were recorded. At the time of exchange, 62% of infants had other neonatal morbidities. Outcomes were stratified according to gestational ages < or =32 weeks, 33 to 36 weeks, and > or =37 weeks. RESULTS: Overall, 74% of exchanges were associated with an adverse event. The most common events were thrombocytopenia (44%), hypocalcemia (29%), and metabolic acidosis (24%), of which 69%, 74%, and 44%, respectively, required treatment. There were two serious adverse events, both in infants with other serious neonatal morbidities: seizures in one infant and the death of a critically ill preterm infant (body weight 731 g, gestational age 25 weeks). There were no cases of sepsis, necrotizing enterocolitis, or cardiac arrest. Adverse events were more frequent in exchanges done on preterm infants: < or =32 weeks (87%), 33 to 36 weeks (78%), and > or =37 weeks (67%), and in infants with other neonatal morbidity (79% vs 57%; P=.08). Controlling for neonatal morbidity, we found the odds of an adverse event were significantly higher when both umbilical venous and arterial catheters were used compared with other methods of exchange (88% vs 58%; OR, 5.17; 95% CI, 1.1, 34.2; P=.03). CONCLUSIONS: The majority of adverse events associated with exchange transfusion are laboratory abnormalities and are asymptomatic and treatable.     

THE EFFECT OF FEEDS OF DIFFERING COMPOSITION ON ENTERO-INSULAR HORMONE SECRETION IN THE FIRST HOURS OF LIFE IN HUMAN NEONATES

Abstract. Little is known on the enteral stimuli for gastro-intestinal hormone release in newborn infants. We have compared the effect of the first feed of human breast milk (5 ml/kg) or 10% dextrose (5 ml/kg) on blood glucose and plasma gastrin, enteroglucagon, Gastric Inhibitory polypeptide (GIP), pancreatic glucagon, and insulin in 21 full-term infants at 4–6 hours of age. The first feed of human milk caused a rise in blood glucose and plasma insulin, gastrin and enteroglucagon, but no change occurred in GIP or pancreatic glucagon. The 10% dextrose feed did not stimulate enteroglucagon release, although similar changes occurred in blood glucose and plasma insulin and gastrin. We conclude that the composition of the feed influences the pattern of gastro-intestinal hormone release during the first hours of life and that the entero-insular responses to feeding differ in the neonate and the adult.     

Interactions of IgM ABO antibodies and complement with methoxy-PEG-modified human RBCs

BACKGROUND: RBCs modified with cyanuric chloride activated methoxy-PEG (CmPEG; 5000 Da) are less immunogenic than untreated RBCs, and their use thus may reduce the risk of alloimmunization in chronically transfused patients. STUDY DESIGN AND METHODS: To further examine the potential utility of CmPEG-RBCs, the effects of derivatization on an arm of the immune system that plays an important role in transfusion rejection-the complement system--were determined. RESULTS: When CmPEG-RBCs were incubated in autologous or heterologous ABO-matched serum, no classical or alternative pathway consumption was found, no C3a was generated, no cell-bound C3b or C9 was detected, and no cell lysis occurred. Cell-bound complement regulation was normal for CmPEG-RBCs, as determined by acidified serum or reactive lysis assays. CmPEG-RBCs differed from control RBCs only when incubated in ABO-mismatched serum. In that case, CmPEG modification failed to protect against ABO antibody-dependent complement-mediated lysis. Indeed, cell lysis was actually enhanced at CmPEG concentrations >1.0 mM. CONCLUSION: The enhanced lysis of CmPEG-RBCs in ABO-mismatched serum correlated with increased IgM binding and C3a generation and elevated C3b and C9 membrane deposition. While PEG modification effectively blocks non-ABO antigens, these data show that ABO matching is still required. Once ABO-matched, these modified RBCs retain great potential for the prevention of alloimmunization.     

THE INTERACTION OF FRUCTOSE, DEXTROSE AND ETHANOL ON HUMAN PERFORMANCE

1. The effects of orally administered fructose (1.2 g.kg^?1) and dextrose (1.2 g.kg^?1) on the performance decrement induced by ethanol (1.0 g.kg^?1) in a series of perceptual, cognitive and motor tests were studied in twelve healthy, paid University student volunteers using a double-blind cross-over design. Ethanol was consumed at a constant rate over 20 min and the hexoses or placebo were given approximately 40 min later. 2. The peak blood ethanol concentration was attained earlier when the subjects also received either hexose than after placebo but although its rate of fall was unaffected, significantly lower ethanol concentrations were encountered in the hexose-treated groups in the latter part of the experiment. 3. In general, the subjects were impaired to a slightly lesser degree when they received a combination of hexose and ethanol than after ethanol alone. There were no differences between the effects of fructose and dextrose. 4. The results do not support contentions that fructose is able to accelerate a return to sobriety and observed differences between hexose and placebo-treated groups were attributed to an effect on the absorption of ethanol rather than its metabolism.     

Development of Means to Augment Peritoneal Urea Clearances: The Synergistic Effects of Combining High Dialysate Temperature and High Dialysate Flow Rates with Dextrose and Nitroprusside

By combining: a) nitroprusside (4.5 mg/L); b) dextrose concentration of 42.5 gm/L; c) dialysate temperature of 42°C and d) dialysate flow rates of 3.5 L/hour in seven uremic subjects on C APD, it was possible to increase peritoneal urea clearance up to 35.6 ± 3.8 ml/min/1.73 m² (range 30.3 to 42.2). This effect in six out of seven cases was associated with a fall in blood pressure and an increase in heart rate. This study is the first which deals with a combination of these factors and demonstrates that this approach is easy to handle, does not require the use of mechanical devices, and is available at any bedside.     

IL-13 attenuates early local CXCL2-dependent neutrophil recruitment for Candida albicans clearance during a severe murine systemic infection

To investigate the role of IL-13 during a severe systemic Candida albicans infection, BALB/c control and IL-13^?/? mice were examined for colony forming units (CFU) in the kidneys and survival days after intravenous infection. Proinflammatory mediators and cell recruitment into the tissue were measured by quantitative real-time PCR, a multiple ELISA system, and morphological cell differentiation. The IL-13^-/- group exhibited a lower CFU number in the kidneys at 4 days and survived longer than the control mice, which was accompanied by significantly higher expression of C-X-C motif ligand 2 (CXCL2), IFN-γ, and polymorphonuclear neutrophils (PMNs) in the infected kidneys. By contrast, the expression of transforming growth factor β (TGF-β) and IL-17?A on day 10 were significantly higher in the control mice than in the IL-13^-/- group. When using an intratracheal infection model, the IL-13^-/- group recruited a greater number of PMNs in 6?h, with rapidly increased CXCL2 in the alveolar space. In vitro testing with cultured bone-marrow-derived cells demonstrated rapid CXCL2 mRNA upregulation at 3?h after contact with C. albicans, which decreased with recombinant IL-13 pretreatment, whereas rIL-13 retained TGF-β upregulation. In a murine model of Candida systemic infection, preexistent IL-13 limits both the rapid CXCL2 elevation and PMN aggregation in the target organ to suppress inflammatory mediators, which also attenuates local pathogen clearance within four days.     

Maintenance fluids in prehospital care: Crystalloid versus dextrose solutions—Is there a difference?

D₅W is the maintenance fluid often used in prehospital care when transporting patients with cardiac or central nervous system processes. However, there is evidence that dextrose solutions are potentially harmful, and that suggests isotonic crystalloid solutions are the preferred maintenance fluid in treating emergent patients regardless of their underlying disease. Dextrose solutions may exacerbate cellular ischemic damage and they cannot be used to resuscitate hypotensive patients. Crystalloids do not cause fluid overload when used at maintenance rates and are effective resuscitative agents in managing hypotention: The use of a single crystalloid solution in the prehospital environment would simplify equipment stocking and management protocols, minimize cost, and would not have an adverse impact on patient care.