Changes in erythrocytic deformability and plasma viscosity in neonatal ictericia

Shape oscillations of single blood drops: applications to human blood and sickle cell disease

Sickle cell disease (SCD) is an inherited blood disorder associated with severe anemia, vessel occlusion, poor oxygen transport and organ failure. The presence of stiff and often sickle-shaped red blood cells is the hallmark of SCD and is believed to contribute to impaired blood rheology and organ damage. Most existing measurement techniques of blood and red blood cell physical properties require sample contact and/or large sample volume, which is problematic for pediatric patients. Acoustic levitation allows rheological measurements in a single drop of blood, simultaneously eliminating the need for both contact containment and manipulation of samples. The technique shows that the shape oscillation of blood drops is able to assess blood viscosity in normal and SCD blood and demonstrates an abnormally increased viscosity in SCD when compared with normal controls. Furthermore, the technique is sensitive enough to detect viscosity changes induced by hydroxyurea treatment, and their dependence on the total fetal hemoglobin content of the sample. Thus this technique may hold promise as a monitoring tool for assessing changes in blood rheology in sickle cell and other hematological diseases.

Changes of red blood cell rheology in newborns with congenital hypothyroidism during treatment

AIM

We aimed to evaluate the deformability characteristics of RBC and the affecting factors in newborns diagnosed with congenital hypothyroidism (CH) and to compare the outcomes after the L-thyroxin treatment.

PATIENTS AND METHODS

Enrolled subjects were divided into two subgroups as "patients" and age-matched healthy "controls". First blood samples were taken from all subjects for measuring elongation index (rEI) and osmotic fragility of RBC (OF), hematic and biochemical analytes affecting the RBC deformability in the neonatal age. All parameters were repeated a month after provided euthyroid state following the treatment in patients and age-matched healthy controls.

RESULTS

There was no difference between both groups in terms of complete blood count parameters and serum analytes (albumin, bilirubin and fibrinogen) except expected age-related changes in the first and second readings. Serum lipid/lipoprotein levels of both groups remained unchanged except triglyceride levels during the study period. The rEI of the patients were lower than that of controls in the first and second readings. The rEIs of the patients became increased, reaching (not equal) the levels of their controls during L-thyroxin treatment. Osmotic fragility of the patients was detected as lower than controls in the first and second readings, and became better during L-thyroxin treatment.

CONCLUSION

Our results indicate that some changes may occur on the hematic and biochemical analytes affecting the RBC deformability features. Neonates with CH have the worst rEI initially, but they reached the indices of the healthy infants thanks to L-thyroxin treatment. Also, their OF features have been improved by L-thyroxin.

Bilirubin toxicity to human erythrocytes: a review

Neonatal jaundice, a physiologic condition reflecting the interplay between developmentally modulated changes in bilirubin production and metabolism, affects virtually all newborn infants. Usually, it is an entirely benign process that is resolved at the end of the first week of life without treatment or sequelae. However, in a small percentage of neonates, unconjugated hyperbilirubinemia can pose a neurotoxic risk especially in the presence of aggravating conditions such as a diminished albumin binding capacity and/or affinity, acidosis, displacing drugs and prematurity. Although neuronal cells are considered the main target for unconjugated bilirubin (UCB) toxicity, circulating cells are also affected during neonatal hyperbilirubinemia. Moreover, the UCB ability to cause hemolysis shall further aggravate neonatal jaundice through a vicious circle. In this review, we summarize the most relevant data obtained by our group regarding UCB toxicity and the role of some risk factors for kernicterus. In order to improve the risk assessment of neurotoxicity it is essential to understand the underlying mechanisms of UCB pathophysiology.

Decreased deformability of donor red blood cells after intrauterine transfusion in the human fetus: possible reason for their reduced life span?

BACKGROUND

The life span of donor red blood cells (RBCs) is reduced in the fetus with Rh hemolytic disease. This may have resulted from donor or recipient factors.

STUDY DESIGN AND METHODS

Studied in vitro was the effect of gamma irradiation on hemolysis, methemo-globin (metHb), and lipid peroxidation of donor RBCs and the ability of fetal and adult plasma to protect irradiated RBCs from induced lipid peroxidation. Also studied in vivo were the effects after the time that donor RBCs reside in the fetus by measuring its lipid peroxidation, cholesterol-to-phospholipid ratios, and deformability of RBCs.

RESULTS

Irradiation barely increased hemolysis and metHb formation and did not increase lipid peroxidation. Plasma samples of D+ fetuses inhibited induced oxidative stress less than plasma samples of adults. Nevertheless, in vivo lipid peroxidation of the donor RBC membrane had not increased, whereas the molar cholesterol-to-phospholipid ratio increased from 1.08 +/- 0.11 to 1.38 +/- 0.12. It became identical to that of the fetal RBCs (1.44 +/- 0.12). Before transfusion, the deformability of the adult RBCs (elongation index, 0.578 +/- 0.013) was better than that of the fetal cells (elongation index, 0.494 +/- 0.027), but decreased to fetal levels after transfusion (elongation index, 0.518 +/- 0.039).

CONCLUSION

Irradiation of the RBCs and a reduced fetal antioxidant capacity do not lead to in vivo lipid peroxidation. The shorter life span of donor cells in the fetus probably results from a decreased deformability of the RBCs after transfusion, most likely owing to an increased cholesterol-to-phospholipid ratio.

Impairment of blood rheology by cholestatic jaundice in human beings

Bilirubin and bile acids may affect erythrocytes. We investigated blood viscosity and erythrocyte structure in patients with cholestatic jaundice ex vivo and studied the short-term effects of bilirubin and bile acids in vitro. Seventeen patients with cholestatic jaundice and controls were studied. Whole-blood viscosity (adjusted hematocrit 45%) at high (94.5 sec(-1)) and low (0.1 sec(-1)) shear rate and plasma viscosity were measured. Erythrocyte structure was assessed in wet preparations of fixed cells. In vitro whole blood was incubated with increasing concentrations of bilirubin (83% conjugated) and bile acids (cholic, lithocholic, deoxycholic, and chenodeoxycholic acid) and the abovementioned investigations were performed. In patients we observed increased whole-blood viscosity at high shear rate (5.82 +/- 0.69 vs 5.04+/- 0.27 mPa. sec, P =.0001), plasma viscosity (1.48 +/- 0.22 vs. 1.23 +/- 0.07 mPa. sec, P =.0004), and fibrinogen level (4.70 +/- 0.98 g/L vs 2.63 +/- 0.21 g/L, P < 0.001) were observed. The incubation of normal erythrocytes in patients' plasma confirmed an increase in blood viscosity at high shear rate. Erythrocytes from patients with jaundice demonstrated a slight degree of stomatocytic shape transformation (P <.0001). In vitro, bilirubin did not affect erythrocyte shape. Cholic and lithocholic acids caused a slight stomatocytic shape transformation, whereas deoxycholic acid and chenodeoxycholic acid influenced neither blood viscosity nor erythrocyte structure. Patients with cholestatic jaundice have increased whole-blood and plasma viscosity and slightly altered red blood cell shape, possibly the result of a combination of increased levels of bilirubin and bile acids plus an acute-phase reaction.