Application of a sensitive and specific reagent for the determination of serum iron to the Bayer DAX48.

We describe a modification of a previously described serum iron procedure applied to the Bayer DAX48 (Bayer Diagnostics, Tarrytown, NY) automated chemistry analyzer. The iron-ligand used in this assay, 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamine) phenol (nitro-PAPS), has a molar absorptivity of 94,000 L mol(-1) cm(-1), which is three to four times more sensitive than the more commonly used ligands. The increased sensitivity of the iron-ligand complex facilitates modification of a Ferene S method that requires a smaller sample volume while it maintains the precision of the assay. Because the reagent does not contain ascorbate, the "onboard" stability has been increased to more than 4 weeks. The reagent seems to be quite insensitive to icterus and hemolysis. Furthermore, the interference of turbidity caused by triglycerides, abnormal proteins, or fibrinogen, present in samples from patients undergoing anticoagulant therapy, seems to have been eliminated.

Aortic to right ventricular shunt for pulmonary atresia and intact ventricular septum.

Acute or chronic myocardial ischemia may develop in patients with pulmonary atresia with intact ventricular septum and right ventricular-dependent coronary circulation. In such cases an aorta to right ventricle shunt may be used to reverse this ischemia. This report summarizes our experience with the placement of an aortic to right ventricular shunt in 5 patients. The shunts were made of Gore-Tex and ranged from 4 mm to 8 mm. Associated procedures were bidirectional Glenn (n = 2) and Fontan (n = 2). All 5 patients survived the procedure with documented early graft patency and no evidence of ischemia.

Acute hemodynamic effects of adjustable atrial septal defect closure in the lateral tunnel Fontan procedure.

OBJECTIVES: This study evaluated the acute hemodynamic changes with atrial septal defect closure in the postoperative period in patients undergoing the Fontan procedure. BACKGROUND: The adjustable atrial septal defect is a modification of the Fontan procedure designed to improve cardiac output and reduce systemic venous hypertension during the postoperative period. Limited information is available on the effects of inter-atrial shunting on the physiology of direct cavopulmonary connection. METHODS: In 11 patients (aged 9 months to 14.5 years), the atrial septal defect was closed 8 h to 4.6 days (mean 1.7 days) postoperatively. Indications for closure included mean right atrial pressure < 15 mm Hg or arterial oxygen saturation < 80%, or both. RESULTS: Data presented are mean values +/- 1 SD. Mean right atrial pressure was 13.4 +/- 3.0 mm Hg on admission to the intensive care unit, 10.0 +/- 2.0 mm Hg (p = 0.02) immediately before closure and 11.4 +/- 2.8 mm Hg (p = 0.02) after closure. There was a significant decrease in cardiac output, as calculated from arteriovenous oxygen saturation difference (26 +/- 9%, p = 0.003), Doppler aortic flow (19 +/- 9%, p = 0.0002) and ventricular volumes by two-dimensional echocardiography (20 +/- 8%, p = 0.0001). Arterial oxygen saturation increased from 82 +/- 5% to 94 +/- 4% (p = 0.0001), and arteriovenous oxygen saturation difference increased from 25 +/- 8% to 33 +/- 9% (p = 0.0001). Systemic oxygen delivery decreased from 727 +/- 354 to 655 +/- 325 ml/min per m2 (p = 0.02). One patient required reopening of the atrial septal defect. CONCLUSIONS: These data demonstrate that a controlled right to left atrial shunt improves cardiac output and systemic oxygen delivery and facilitates the postoperative management of patients after the Fontan procedure. Atrial septal defect closure increases systemic saturation to normal values and prevents potential systemic embolization but significantly decreases oxygen delivery and might limit exercise tolerance.

Rapid screening method for polymorphism of group A apolipoproteins.

Polymorphism of apolipoproteins AI and AII (apo AI and apo AII) can be easily investigated in plasma by a simple method involving a 30-min incubation of EDTA plasma in the presence of urea, dithiothreitol, and Nonidet P-40 followed by subsequent isoelectric focusing (IEF). The sample (2 microL) was applied to an ultrathin flat acrylamide gel of pH range 4-6, and focused using a Bio-Rad Mini IEF Cell for 1.5 h at a maximum of 500 V. Coomassie Blue R-250 was used to visualize the apolipoproteins. To verify the identity of the different apolipoproteins after IEF, the gel was immunofixed directly with anti-apo AI, or immunoblotted on polyvinylidene difluoride (PVDF) membrane using monospecific antibodies to apo AI and apo AII and an anti-immunoglobulin-alkaline phosphatase conjugate. High-density lipoprotein (HDL) was used as a standard for Apo AI variants. Employing these techniques, human plasma apo AI was resolved into one major band (apo AI0, pI 5.54), and four minor bands identified as apo AI+2 (pI 5.75), apo AI+1 (pI 5.66), apo AI-1 (pI 5.45), and apo AI-2 (pI 5.34). Apo AII was resolved into one major isoprotein designated as apo AII0 (pI 4.87), and two minor isoforms apo AII+1 and apo AII-1 which focused at pIs of 5.18 and 4.58, respectively. The results showed that these methods can be used to identify apo AI and AII isoforms without prior ultracentrifugation to isolate the HDL. The entire procedure, including IEF, fixation (chemical or immunofixation), and staining, can be accomplished in 5 h compared to 2 days using previously reported technique.(ABSTRACT TRUNCATED AT 250 WORDS)

A simple micromethod for rapid assessment of the distribution of apolipoprotein C isoforms in very-low-density lipoprotein.

A simple and rapid isoelectric focusing method for quantifying Apo C isoforms of triglyceride-rich lipoprotein was developed. The very-low-density lipoprotein (VLDL) was isolated from 100 microL of EDTA plasma using a Beckman Airfuge ultracentrifuge. The delipidated VLDL was applied to an ultrathin flat acrylamide gel, and focused using a Bio-Rad Mini IEF Cell, for 1.5 h at a maximum of 500 V. Apo CII and Apo CIII in VLDL were resolved into four major bands, CIII0 (PI 4.91), CII (PI 4.78), CIII1 (PI 4.72), and CIII2 (PI 4.53). The method demonstrated within-run and between-run CVs of 2.7% to 11.9% and 4.4% to 12.2%, respectively. The relative percentage of C apoproteins and the ratio of CII to CIII found in VLDL from plasma of normal, chronic renal failure, and hyperlipidemic subjects agreed with previously published data.

Nifedipine: effects on fetal and maternal hemodynamics in pregnant sheep.

We investigated the effects of nifedipine, a calcium entry blocker, on the fetal and maternal circulation. Nifedipine was administered intravenously for 30 minutes to chronically instrumented pregnant ewes. Infusion of 5 micrograms.kg-1.min-1 resulted in a 30% to 50% increase in total and regional fetal cerebral blood flow to the brain stem, watershed, and subcortical regions (p less than 0.05), without a significant change in fetal oxygenation or cardiac output. Infusion of 10 micrograms.kg-1.min-1 decreased uterine blood flow by 21% (p less than 0.001) and fetal arterial oxygen content by 15% (p less than 0.01), with no further increase in fetal cerebral blood flow. Maternal arterial pressure decreased and heart rate increased (p less than 0.001) without variation of arterial blood gases. Significant plasma levels of nifedipine were detected in the fetal and maternal circulations. In view of the potential adverse effects on the fetus, further studies are needed before nifedipine is considered for use in human pregnancy.

Thoracic duct lymph flow: a comparative study in newborn and adult sheep.

To understand better developmental changes in body fluid dynamics, we studied thoracic duct lymph flow in 9 newborn and 5 adult sheep. The experiments were carried out under general anaesthesia following bilateral ligation of the renal vessels and ureters. After a 30 min control period, we administered three successive 5-min intravenous infusions of isotonic saline equivalent to 2% of body weight each, at 30-min intervals. The average basal lymph flow rate was 0.157 +/- 0.033 (SEM) ml.min-1.kg-1 and 0.046 +/- 0.018 ml.min-1.kg-1 in newborns and adults respectively (p less than 0.05). Fluid overloading resulted into similar intravascular retentions at the end of each 30-min period in both groups although the increase in lymph flow was repeatedly more than three times higher in the newborns. The more pronounced lymph flow response in the newborns could not be accounted for only on the basis of a difference in capillary filtration. We speculate that interstitial forces and/or the lymphatic pumping activity play a greater role in facilitating fluid movements in the newborn lamb than in the adult ewe. Overall, the higher capacity of the newborn to eliminate excess interstitial fluid constitutes a significant factor in the body's defense against oedema.