Heterogeneous phenotype of Hereditary Xerocytosis in association with PIEZO1 variants.

Hereditary Xerocytosis (HX) is an autosomal dominantly inherited congenital hemolytic anemia associated with erythrocyte dehydration due to decreased intracellular potassium content resulting in increased mean corpuscular hemoglobin concentration. The affected members of HX families show compensated anemia with splenomegaly, hemosiderosis, and perinatal edema but are in large part transfusion independent. Functional studies show a link between mutations in mechanosensitive ion channel, encoded by PIEZO1 gene and the HX. We identified new PIEZO1 variants that are likely pathogenic in three phenotypically characterized multi-generational HX Brazilian families. Interestingly, one missense variant of the PIEZO1 gene identified, p.E2494V was associated in trans with the previously reported most frequent pathogenic duplication p.E2496ELE. The three-dimensional structure of the human protein modeled using structural coordinates of the mouse Piezo1 solved by cryo-electron microscopy (Cryo-ME) showed that the two identified variants, p.M2007L and p.T2014I, are localized to an important mechanosensitive transmembrane domain suggesting a conformational mechanism for altered channel's gating. The p.E2496ELE variant identified alters the extension of helix α1 bringing it much closer to the beam affecting the position of it structure at the end of the pore.

Hb S-São Paulo: a new sickling hemoglobin with stable polymers and decreased oxygen affinity.

Hb S-São Paulo (SP) [HBB:c.20A>T p.Glu6Val; c.196A>G p.Lys65Glu] is a new double-mutant hemoglobin that was found in heterozygosis in an 18-month-old Brazilian male with moderate anemia. It behaves like Hb S in acid electrophoresis, isoelectric focusing and solubility testing but shows different behavior in alkaline electrophoresis, cation-exchange HPLC and RP-HPLC. The variant is slightly unstable, showed reduced oxygen affinity and also appeared to form polymers more stable than the Hb S. Molecular dynamics simulation suggests that the polymerization is favored by interfacial electrostatic interactions. This provides a plausible explanation for some of the reported experimental observations.

[Effects of recombinant human erythropoietin in preterm newborns with infectious diseases]. / Efeitos da eritropoetina recombinante humana em recém-nascidos pré-termo com doenças infecciosas.

OBJECTIVE: To study the effects of recombinant human erythropoietin (rHuEpo) in preterm newborns (PTNs) with serious infectious diseases. METHODS: A not randomized case-control study was carried out in 34 preterm newborns with diagnosis of serious infectious pathologies, gestational age up to 35 weeks, birth weight less than 1500 g and clinical stability. Newborns selected for treatment with rHuEpo received 400 U/kg erythropoietin ss, subcutaneously twice a week. Oral iron supplementation was initiated when the levels of serum ferritin were lower than 60 mcg/l. The study was continued for six weeks or until the patient was discharged from the hospital. Erythropoiesis, granulopoiesis, thrombocytopoiesis, the need for transfusions and the occurrence of new episodes of infectious disease were analyzed. RESULTS: In the treated group there was a significant increase in the number of reticulocytes, although there was no statistically significant difference between the groups with regard to the number or volume of transfusions. There was no significant difference in neutrophils and platelet values. CONCLUSION: The use of rHuEpo, 800 U/kg/week, in PTNs with infectious diseases was effective in inducing erythropoiesis, without significant changes in the number of neutrophils or platelets. This strategy, and the accurate control of the blood collected for laboratory exams, may be beneficial for prevention of the anemia in PTNs with serious infectious diseases.

Efeitos da eritropoetina recombinante humana em recém-nascidos pré-termo com doenças infecciosas / Effects of recombinant human erythropoietin in preterm newborns with infectious diseases

OBJETIVO: Analisar os efeitos da eritropoetina recombinante humana (rHuEpo) em recém-nascidos pré-termo com doenças infecciosas graves. MÉTODOS: Foi realizado um estudo controlado, não randomizado, em 34 recém-nascidos com diagnóstico de patologias infecciosas graves, peso de nascimento igual ou inferior a 1500 g, idade gestacional inferior a 35 semanas e estabilidade clínica. Os recém-nascidos designados para o tratamento com rHuEpo receberam a eritropoetina ß na dose de 400 UI/kg, duas vezes por semana, por via subcutânea. A suplementação oral com ferro foi iniciada quando os níveis de ferritina sérica foram inferiores a 60 mcg/L. O estudo foi realizado durante seis semanas ou até a alta hospitalar do paciente. Foram avaliados a eritropoese, o número de transfusões, o número de neutrófilos, a contagem de plaquetas e os episódios de novas infecções durante o tratamento com o hormônio. RESULTADOS: Houve aumento significativo do número de reticulócitos no grupo tratado; entretanto, não houve impacto sobre o número ou volume de transfusões. Não foram observadas alterações no número de neutrófilos ou plaquetas. CONCLUSÃO: O uso de rHuEpo em RNPT com doenças infecciosas, na dose de 800 UI/Kg/semana, foi efetivo para induzir eritropoese, sem ocorrerem alterações significativas sobre o número de neutrófilos ou plaquetas. Essa estratégia, associada ao controle rigoroso do volume de sangue retirado para exames, poderá ser benéfica na prevenção da anemia em RNPT com infecção grave.

OBJECTIVE: To study the effects of recombinant human erythropoietin (rHuEpo) in preterm newborns (PTNs) with serious infectious diseases. METHODS: A not randomized case-control study was carried out in 34 preterm newborns with diagnosis of serious infectious pathologies, gestational age up to 35 weeks, birth weight less than 1500 g and clinical stability. Newborns selected for treatment with rHuEpo received 400 U/kg erythropoietin ß, subcutaneously twice a week. Oral iron supplementation was initiated when the levels of serum ferritin were lower than 60 mcg/l. The study was continued for six weeks or until the patient was discharged from the hospital. Erythropoiesis, granulopoiesis, thrombocytopoiesis, the need for transfusions and the occurrence of new episodes of infectious disease were analyzed. RESULTS: In the treated group there was a significant increase in the number of reticulocytes, although there was no statistically significant difference between the groups with regard to the number or volume of transfusions. There was no significant difference in neutrophils and platelet values. CONCLUSION: The use of rHuEpo, 800 U/kg/week, in PTNs with infectious diseases was effective in inducing erythropoiesis, without significant changes in the number of neutrophils or platelets. This strategy, and the accurate control of the blood collected for laboratory exams, may be beneficial for prevention of the anemia in PTNs with serious infectious diseases.

Avaliaçäo do quociente das proteínas da membrana eritrocitária e da proteína 3 nas anemias esferocíticas / Red cell membrane proteins ratios in relation to band 3 in spherocytosis

As proteínas da membrana eritrocitária foram estudadas por meio de eletroforese de poliacrilamida (SDS-PAGE) em nove pacientes, utilizando-se o quociente de todas as bandas protéicas em relaçäo à banda 3; um grupo controle normal foi utilizado. O quociente espectrina/banda 3 dos pacientes com esferocitose foi baixo (p=0,0001), o que indica deficiência de espectrina. Foi também observado um aumento relativo geral das demais proteínas, em especial das bandas 4.1 e 4.5 (p=0,046 e p=0,0001, respectivamente), o que pode ser imputado à diminuiçäo da concentraçäo das espectrinas