The adaptability of red blood cells.

The most important function of red blood cells (RBCs) is the carrying of oxygen, but they are also involved in inflammatory processes and during coagulation. RBCs are extremely deformable and elastic, as they are exposed to shear forces as they travel through the vascular system. In inflammatory conditions, and in the presence of hydroxyl radicals, RBCs loose their discoid shape. Here, ultrastructure of RBCs is studied using a scanning electron microscope, and we determine how fast changes in healthy individuals are noted after exposure to iron and glucose. We compare shape changes in these experiments to RBCs from diabetic and hemochromatosis patients (wild type, as well as hereditary hemochromatosis with mutations H63D/H63D, C282Y/C282Y, H63D/C282Y, C282Y/wild type and H63D/wild type). Thrombin is also added to whole blood exposed to iron, glucose and blood from diabetes and hemochromatosis patients. RBCs are easily deformed to a pointed shape in smears, and, with the addition of thrombin they are entrapped in the fibrin mesh of dense matted fibrin deposits. This entrapping causes severe shape changes due to the pressure of the fibrin onto the stressed cells. The most important observation of the current research is therefore how fast RBC can adapt in a changed environment and that the pressure of fibrin fibers may trap the RBC tightly in the resulting clot.

Simultaneous determination of aminomethylbenzoic acid, cefminox sodium and etamsylate in human urine by capillary electrophoresis.

A sensitive and selective capillary electrophoresis method is developed, for the first time, for effective separation and simultaneous determination of aminomethylbezoic acid (PAMBA), cefminox sodium (CMNX) and etamsylate (ETM). The electrophoresis conditions were investigated and optimized. A 25 mM phosphate solution (pH 8.5) was used as a buffer and the peak area was determined with UV detection at 216 nm wavelength under 18 kV separation voltage. Under optimal conditions, the three drugs can be separated effectively. Good linearity was achieved in 3.13-150 microg/mL for PAMBA, 6.25-150 microg/mL for CMNX and 3.13-150 microg/mL for ETM, with the correlation coefficients of >0.999. The limit of detection (LOD) for PAMBA, CMNX and ETM was 1.04, 2.08 and 1.04 microg/mL, respectively. Their recoveries in human urine were in the range from 90.2% to 101% with the RSD (n=5) of 0.7-3.1%. The proposed method is simple, rapid and accurate, and provides the sensitivity and linearity necessary for analysis of the test drugs in human urine at clinically relevant concentrations.

Urinary aprotinin as a predictor of acute kidney injury after cardiac surgery in children receiving aprotinin therapy.

Proteomic analysis has revealed potential early biomarkers of acute kidney injury (AKI) in children undergoing cardiopulmonary bypass (CPB), the most prominent one with a mass-to-charge ratio of 6.4 kDa. The objective of this study was to identify this protein and test its utility as a biomarker of AKI. Trypsin-digested protein bands were analyzed by tandem mass spectrometry (MS/MS) to identify the protein in urine samples. Surface-enhanced laser desorption/ionization time-of-flight analysis and a functional activity assay were performed to quantify urinary levels in a pilot study of 106 pediatric patients undergoing CPB. The protein was identified as aprotinin. Urinary aprotinin levels 2 h after initiation of CPB were predictive of AKI (for functional assay: 92% sensitivity, 96% specificity, area under the curve of 0.98). By multivariate analysis, the urinary aprotinin level 2 h after CPB was an independent predictor of AKI (beta = 0.001, P < 0.0001). The 2 h urinary aprotinin level correlated with serum creatinine, duration of AKI, and length of hospital stay. We concluded that urinary aprotinin levels 2 h after initiation of CPB predict the development of AKI and adverse clinical outcomes.

What happens to hemostatic agents in contact with urine? An in vitro study.

BACKGROUND AND PURPOSE: As the indications for topical hemostatic agents increase in urology, the question arises: what happens to these agents when they enter the urinary collecting system? To answer this question, we performed a series of in-vitro experiments mixing three hemostatic agents with normal and sanguineous urine. MATERIALS AND METHODS: Four commercially available topical hemostatic products: oxidized regenerated cellulose (Surgicel; Ethicon, Somerville, NJ), fibrin sealant (Tisseel VH Kit; Baxter Health Care Corporation, Irvine, CA), gelatin matrix hemostatic sealant (FloSeal; Baxter Health Care), and polyethylene glycol (CoSeal; Cohesion Technologies, Palo Alto, CA) were studied. Human urine (10 mL) was added to samples of each substance; this was done in triplicate. The 12 sample tubes were then capped and placed on a tube shaker at slow speed and 37 degrees C. Observations regarding consistency of the material were made at 6, 12, 24, 48, 72, 96, and 120 hours (5 days). Gelatin matrix hemostatic sealant was further tested in urine with various amounts of blood or blood clot; observations were again recorded out to 5 days. RESULTS: Surgicel maintained its solid form when it initially came in contact with urine, but over a period of 5 days, it transformed into a mucoid substance with visible free-floating fibers. It did not dissolve completely in urine within 5 days. Gelatin matrix was immediately transformed by urine into a fine colloidal suspension that did not change over the 5 days of the study. Fibrin glue, after mixing of the two components (fibrinogen and thrombin) directly in the urine, and polyethylene glycol immediately formed a solid clot at the bottom of the test tube on contact with the urine. When the mixture of fibrin sealant was allowed to form for 15 minutes and then added to urine, it again maintained a solid form. After 72 hours, the fibrin glue became a semisolid gelatinous plug. On analysis at 5 days, the fibrin sealant clot had transformed into a cohesive mucoid gel, and the polyethylene glycol clot had not changed. The gelatin matrix hemostatic sealant, when in contact with blood or blood clot, appeared to either become part of a clot or to remain in a colloidal suspension. At 5 days, all clots had dissolved to fine particulate suspensions, and the gelatin matrix appeared as a fine suspension. CONCLUSION: Fibrin glue and oxidized regenerated cellulose maintain a solid form when initially placed in direct contact with urine and then assume a semisolid gelatinous state, which is still present at 5 days. Polyethylene glycol forms a solid clot initially and does not change after 5 days. Only hemostatic gelatin matrix remained as a fine particulate suspension in both normal and sanguineous urine. The implications of these findings with regard to sealing the renal parenchyma or small violations of the collecting system after percutaneous or laparoscopic surgery await in-vivo testing.

Pharmacokinetics and antidiuretic effect of intravenous administration of desmopressin in orally overhydrated male volunteers.

In order to study the antidiuretic activity of desmopressin in healthy human subjects, a study design has previously been used with subjects orally hydrated. The objective of the present study was to investigate the pharmacokinetics and the antidiuretic activity of desmopressin administered as an intravenous infusion to eight orally hydrated male volunteers. After initial ingestion of water corresponding to 15 ml.kg-1 body weight, the overhydration was maintained by replacing the urinary fluid loss by drinking-water. Desmopressin (4 micrograms) was administered intravenously over 10 min. 1.5 hr after the start of the hydration procedure. Blood was sampled and urine was collected at intervals throughout the study day (9.5 hr). The terminal half-life of elimination (t1/2,) of desmopressin was calculated to be 2.97 +/- 0.24 (S.E.M.) hr while the clearance was 1.77 +/- 0.10 ml.min.-1.kg-1 and the volume of distribution at steady state was 373 +/- 30 ml.kg-1. The infusion caused a marked and long-lasting reduction of the urine flow rate. Four hr after the start of the infusion the mean urine osmolality was 909 +/- 46 mOsm.kg-1.

Neurobehavioral effects of low-level methanol vapor exposure in healthy human volunteers.

Methanol-powered vehicles are being introduced in the United States as a solution to air pollution. This study assessed whether acute exposure to methanol vapor at the current industrial threshold limit value of 200 ppm for 4 hr has adverse effects on human neurobehavioral performance. Twenty-six healthy subjects (15 men, 11 women; ages 26-51 years) were exposed to methanol or water vapor for 4 hr while seated in a chamber. The subjects served as their own controls in a randomized, double-blind study design. The variables assessed were serum and urine methanol and formate levels; visual performance (color discrimination and contrast sensitivity); and neurophysiological (auditory evoked potentials) and neurobehavioral performances. Exposure to methanol increased serum concentrations and urinary excretions of methanol, but did not affect formate levels. Overall visual, neurophysiological, and neurobehavioral test outcomes were not significantly affected, unless certain between-subject variables are considered. Slight effects on P-300 amplitude and Symbol Digit testing were noted. We conclude that acute exposure of healthy people to low concentrations of methanol had little effect on these measures of neurobehavioral performance.