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Increased adhesive events between the blood vessel endothelium and red and white cells play a central role in the initiation of vasoocclusive crisis in sickle cell disease (SCD). Soluble VCAM-1 levels are increased in the plasma of sickle cell patients and may be reduced during hydroxyurea (HU) therapy. Reports regarding any changes in soluble ICAM-1 (sICAM-1) levels in sickle cell patients, however, are conflicting, and as yet no beneficial effect of HU upon levels has been observed. Thus, we sought to thoroughly investigate changes in sICAM-1 levels in SCD patients and the effect of HU therapy (20-30 mg/kg/day). Plasma sVCAM-1 levels were significantly higher in steady-state SCD patients than in normal controls (766 ± 86 ng/mL vs. 325 ± 38 ng/mL, respectively, P < 0.0001). sVCAM-1 levels were decreased in patients on HU therapy (543 ± 69 ng/mL) compared to those not taking HU; however, this difference was not significant. Plasma sICAM-1 levels were significantly increased in steady-state SCD patients compared to normal individuals (285 ± 20 ng/mL vs. 202 ± 16 ng/mL, respectively, P = 0.002), and HU therapy significantly reduced sICAM-1 levels in patients (217 ± 12, P = 0.027) to levels approaching those of healthy individuals. sVCAM-1 levels inversely correlated with fetal hemoglobin levels in SCD patients, while a nonsignificant inverse trend was observed between sICAM-1 levels and fetal hemoglobin. In conclusion, plasma sICAM-1 levels were significantly increased in SCD patients, and this increase was reversed by hydroxyurea therapy, possibly reflecting reduced endothelial activation in patients taking HU. Such an event may benefit patients by reducing adhesive interactions between white cells and the endothelium. Am.

Summary Activation of soluble guanylate cyclase (sGC) has been reported to up‐regulate γ‐globin gene transcription in erythroid cell lines and primary erythroblasts. sGC is activated by nitric oxide (NO), subsequently catalysing the conversion of guanosine triphosphate to cyclic guanosine monophosphate (cGMP), which mediates various physiological responses. To study the importance of this mechanism in the erythroid cells of sickle cell patients, cGMP levels were measured in the red blood cells (RBC) of normal individuals, steady‐state sickle cell patients (SS) and SS patients on hydroxyurea (HU) therapy (SS + HU). cGMP levels were found to be significantly higher in RBC of SS patients (SS RBC) than in RBC of normal individuals, and were further increased in RBC of SS + HU patients. cGMP levels correlated with fetal haemoglobin (HbF) levels in SS/SS + HU patients, but not with reticulocyte count. Furthermore, NO‐stimulated sGC activity, following incubation of cells with a NO donor, was significantly greater in SS RBC than in normal RBC. These results demonstrate, for the first time, an increased metabolism of NO mediated by sGC in the SS RBC, which is further increased by hydroxyurea. Augmentation of cGMP levels by NO in erythroid cells may constitute a mechanism for induction of HbF and other erythrocyte functions and represent a possible therapeutic target for treatment of sickle cell disease.

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This study aimed to evaluate the effects of glycated hemoglobin (HbA ) on flow-mediated dilation, intima-media thickness, pulse wave velocity, and left ventricular mass index in patients with resistant hypertension (RHTN) comparing RHTN-controlled diabetes mellitus and RHTN-uncontrolled type 2 diabetes mellitus. Two groups were formed: HbA <7.0% (RHTN-controlled diabetes mellitus: n = 98) and HbA ≥7.0% (RHTN-uncontrolled diabetes mellitus: n = 122). Intima-media thickness and flow-mediated dilation were measured by high-resolution ultrasound, left ventricular mass index by echocardiography, and arterial stiffness by carotid-femoral pulse wave velocity. No differences in blood pressure levels were found between the groups but body mass index was higher in patients with RHTN-uncontrolled diabetes mellitus. Endothelial dysfunction and arterial stiffness were worse in patients with RHTN-uncontrolled diabetes mellitus. Intima-media thickness and left ventricular mass index measurements were similar between the groups. After adjustments, multiple linear regression analyses showed that HbA was an independent predictor of flow-mediated dilation and pulse wave velocity in all patients with RHTN. In conclusion, HbA may predict the grade of arterial stiffness and endothelial dysfunction in patients with RHTN, and superimposed uncontrolled diabetes mellitus implicates further impairment of vascular function.

Sickle cell disease (SCD) is a prevalent genetic disorder that includes sickle cell anemia (hemoglobin SS), hemoglobin SC, and hemoglobin Sb-thalassemia. Patients with SCD present with a defective activation of the alternate pathway of the complement system that increases the risk of capsulate bacteria infection and failure to eliminate antigens, predisposing these patients to autoimmune diseases. The authors describe three patients with SCD that developed systemic lupus erythematosus (SLE). In all patients, SLE diagnosis was delayed because symptoms were initially attributable to SCD. Physicians should be alerted to the possible development of SLE in patients with SCD to not delay the diagnosis and start appropriate treatment.