实验性红细胞增多和慢性缺氧对右心室肥大的影响

为了研究红细胞增多对缺氧性肺动脉高压和右室肥大的影响,将大鼠分为四组:常氧对照组;单纯红细胞增多组;慢性缺氧组;慢性缺氧复合红细胞增多组。结果表明,单纯红细胞增多引起右室V_(max)、右室收缩压和右室重量指数增加。慢性缺氧不仅引起右室±dP/dt_(max)和V_(max)增加,还引起右室收缩压和右室重量指数增加。慢性缺氧复合红细胞增多进一步使右室收缩压和右室重量指数增加。此外,还出现左室重量指数增加。以上结果表明,红细胞增多在缺氧性肺动脉高压和右室肥大中起着重要作用。     

Peri‐ and postnatal rodent development of Hematide,an erythropoiesis‐stimulating agent

BACKGROUND: Aperi‐ and postnatal reproduction toxicity study was conducted in rats treated with Hematide, a synthetic PEGylated peptidic erythropoiesis stimulating agent (ESA). METHODS: Hematide, at IV doses of 0, 0.5, 3, and 15 mg/kg, was administered from implantation through lactation on gestation days (GDs) 5 and 18 and lactation day (LD) 13. RESULTS: Hematide induced pronounced polycythemia in all Hematide‐treated dams. On LDs 2 and 21, hemoglobin (Hgb) increases above control levels were 3.1, 5.2, and 5.0 g/dL and 4.1, 5.1, and 5.5 g/dL at the 0.5, 3, and 15 mg/kg/dose, respectively. There were no effects on parturition, lactation, or maternal behavior in the F0 generation female rats. A slight decrease in pup viability on postpartum days 2–4 and lower body weights and/or body weight gain for the F1 generation were associated with pronounced polycythemia and decreases in maternal body weight gain and/or food consumption at ≥3 mg/kg/dose. Hematide fetal exposure was negligible. No Hematide effect, other than on growth and survival, was noted on developmental, functional, mating, and fertility end points in the F1 generation rats, and no effect on litter or fetal parameters was observed in the F2 generation. The maternal no‐observed‐adverse‐effect level (NOAEL) for Hematide was 0.5 mg/kg, and the NOAEL for parturition and maternal behavior was 15 mg/kg. The NOAEL for F1 pup viability and growth was 0.5 mg/kg/dose. CONCLUSIONS: In conclusion, the Hematide‐associated adverse findings were attributed to exaggerated erythropoiesis (pronounced and prolonged polycythemia) resulting from administration of an ESA to pregnant animals. Birth Defects Res (Part B) 89:155–163, 2010. © 2010 Wiley‐Liss, Inc.     

Nitric oxide scavenging by cell-free hemoglobin may be a primary factor determining hypertension in polycythemic patients

Abstract

We tested the hypothesis that hypertension associated with polycythemia vera (PV) may be related to hemoglobin released from erythrocytes (cell-free hemoglobin, fHb). We assessed hematocrit, mean arterial pressure (MAP), blood viscosity, and the level of fHb and nitrite/nitrate (NO_x) in the plasma of 73 PV patients and 38 healthy controls. The effect of isovolemic erythrocytapheresis (ECP) on the considered parameters was also studied. From the whole group of PV patients a subset of subjects with normal (normotensive patients, n = 16) and elevated MAP (hypertensive patients, n = 57) can be subtracted.

It was found that in comparison with healthy controls, PV patients have significantly (p ≤ 0.01) elevated Hct (0.567 vs. 0.422), blood viscosity (5.45 vs. 3.56 cP), MAP (106.8 vs. 93.8 mmHg), plasma fHb (9.7 vs. 2.8 mg/dL), and NO_x levels (34.1 vs. 27.5 μM). Compared with normotensive patients, hypertensive PV patients demonstrated a higher rise in fHb (10.2 vs. 8.0) and plasma NO_x levels (35.8 vs. 31.0). In PV patients, fHb positively correlates with MAP (r = 0.489), NO_x levels (r = 0.461), hematocrit (r = 0.428), and viscosity (r = 0.393). Blood viscosity positively correlated with hematocrit (r = 0.894), but not with other considered parameters. In PV patients MAP poorly correlated with hematocrit, whereas the correlation between MAP and NO_x altered from ? 0.325 (healthy control) to + 0.268 (PV patients). ECP procedure was associated with a significant (p < 0.01) reduction of hematocrit, fHb, blood viscosity, and MAP. In the normotensive subgroup of PV patients the ECP procedure did not affect MAP. It can be concluded that accelerated scavenging of nitric oxide by fHb rather than high Hct may be a key factor determining the development of hypertension in PV patients.     

Abnormalities of platelet aggregation in chronic myeloproliferative disorders

A large variety of platelet dysfunctions has been described in chronic myeloproliferative disorders. These abnormalities may be due to deficiency of platelet granules, arahidonic acid metabolism defects or platelet membrane glycoproteins abnormalities. In this study we intend to detect the incidence of platelet function defects in 76 patients with various types of chronic myeloproliferative disorders. The platelet activity was studied in vitro by measuring platelet aggregation in response to ADP, epinephrine, collagen, arachidonic acid and ristocetin. These results were subsequently correlated with bleeding time and clinical aspects (bleeding or thrombosis). We found complex changes in platelet response with all agonists, in varied proportions. These abnormalities include absent, decreased or abnormal platelet aggregation response. In a few cases we found a markedly decreased, almost absent platelet response to all agonists while in some patients a normal platelet aggregation was noted. The correlation between these results and template bleeding time, thrombotic or hemorrhagic events and the type of diseases was difficult to establish and sometimes conflictual. Despite this fact, we consider that investigating platelet aggregation may be useful not only for the assesment of the hemostatic balance in chronic myeloproliferative disorders but also for a better insight into cell abnormalities occuring in these pathologic conditions.     

Atpif1基因对K562细胞血红蛋白合成的影响*

目的:探讨线粒体三磷酸腺苷酶抑制因子-1(Atpif1)对血红蛋白合成的影响。方法:首先,将K562细胞分为低氧实验组、常氧对照组,低氧实验组采用O₂浓度为2%,分别培养24 h,48 h,72 h后收集两组细胞,通过细胞增殖-毒性检测试剂盒(CCK8)法检测细胞的活性,流式细胞仪检测低氧对细胞凋亡的影响,通过氯化血红素诱导K562细胞,检测低氧对血红蛋白合成的影响,qRT-PCR检测Atpif1,核因子(NF-κB),delta-氨基酮戊酸合成酶2(Alas2)基因的转录表达。然后,将K562细胞置于低氧培养箱培养并分为空白组,阴性对照组和si-Atpif1三组。转染siRNA,沉默Atpif1基因,观察血红蛋白合成和NF-κB、Alas2基因mRNA水平变化。结果:与常氧对照组相比,低氧实验组K562细胞活性降低、凋亡增加,血红蛋白含量增加(P＜0.05)。Atpif1、Alas2、NF-κB的mRNA表达水平上调(P＜0.05)。与空白对照组和阴性对照组相比,si-Atpif1组血红蛋白含量均有减少(P＜0.05),同时NF-κB、Alas2的mRNA水平也出现下调(P＜0.05)。结论:Atpif1基因参与调控血红蛋白合成,探究其在高原红细胞增多症(HAPC)发生中的作用,可以为防治HAPC提供新的思路和治疗靶点。     

茶多酚对大鼠慢性缺氧损伤保护的实验研究

大鼠在高原环境模拟舱内间断缺氧及注射CoCl2溶液以建立红细胞增多症模型,实验分4组：平原组、慢性缺氧组、高剂量TP＋慢性缺氧组、低剂量TP＋慢性缺氧组,研究茶多酚对慢性缺氧诱导的大鼠红细胞增多症及心肌缺氧损伤的影响．结果显示,茶多酚能够显著抑制缺氧大鼠的红细胞数、血红蛋白和红细胞压积的增加,降低骨髓增生程度,减小缺氧大鼠心室重量指数,增加缺氧大鼠Hermannnwillson指数,同时经茶多酚处萼的缺氧大鼠心肌损伤程度较单纯缺氧组轻．提示,茶多酚对大鼠红细胞增多症有一定的预防作用,同时茶多酚还能减轻慢性缺氧对大鼠的心肌损伤程度．     

高原红细胞增多症患者红细胞二磷酸甘油酸和氧亲和力变化的探讨

在海拔４３００ｍ地区,对１８名移居汉族、２４名世居藏族和２１名高原红细胞增多症（ＨＡＰＣ）患者测定了２,３—二磷酸甘油酸（２,３—ＤＰＧ）和肺通气功能,并进行了血气分析。结果显示：ＨＡＰＣ患者的全血和红细胞内２,３—ＤＰ６浓度均显著高于健康组,但世居、移居健康组之间无明显差异。ＨＡＰＣ组的红细胞２,３—ＤＰＧ和Ｐｄｏ＿２呈显著负相关（ｒ＝—０．７７１,Ｐ＜０．０１）,而在健康组无显著相关（ｒ＝—０．２６,Ｐ＞０．０５）。ＨＡＰＣ组与健康组相比,ｐＨ、Ｐａｏ＿２和Ｓａｏ＿２降低,Ｐａｃｏ＿２和肺泡动脉氧分压差增高。ＨＡＰＣ病人Ｐ＿（５０）为３．７５±０．６６ｋＰａ,健康组为３．４０±０．１２ｋＰａ（Ｐ＜０．０５）,Ｐ＿（５０）与２,３－ＤＰＧ呈正相关（ｒ＝０．５９２,Ｐ＜０．０５）。ＨＡＰＣ组最大呼气中段流量和５０％肺活量最大呼气量明显低于健康组（Ｐ＜０．０１）。本研究提示：①ＨＡＰＣ患者的低氧血症可能与血中２,３－ＤＰＧ浓度过高有关;②轻度肺功能异常亦可促使红细胞进一步增多。     

Molecular drug targets in myeloproliferative neoplasms: mutant ABL1, JAK2, MPL, KIT, PDGFRA, PDGFRB and FGFR1

Therapeutically validated oncoproteins in myeloproliferative neoplasms (MPN) include BCR-ABL1 and rearranged PDGFR proteins. The latter are products of intra- ( e.g. FIP1L1-PDGFRA) or inter-chromosomal ( e.g. ETV6-PDGFRB ) gene fusions. BCR-ABL1 is associated with chronic myelogenous leukaemia (CML) and mutant PDGFR with an MPN phenotype characterized by eosinophilia and in addition, in case of FIP1L1-PDGFRA, bone marrow mastocytosis. These genotype-phenotype associations have been effectively exploited in the development of highly accurate diagnostic assays and molecular targeted therapy. It is hoped that the same will happen in other MPN with specific genetic alterations: polycythemia vera ( JAK2 V617F and other JAK2 mutations), essential thrombocythemia ( JAK2 V617F and MPL5 15 mutations), primary myelofibrosis ( JAK2 V617F and MPL515 mutations), systemic mastocytosis ( KIT D816V and other KIT mutations) and stem cell leukaemia/lymphoma ( ZNF198-FGFR1 and other FGFR1 fusion genes). The current review discusses the above-listed mutant molecules in the context of their value as drug targets.     

Quantitative Proteomics Reveals the Effects of Resveratrol on High‐Altitude Polycythemia Treatment

High‐altitude polycythemia (HAPC) is a common plateau chronic disease in which red blood cells are compensatory hyperproliferative due to high altitude hypoxic environment. HAPC severely affects the physical and mental health of populations on the plateau. However, the pathogenesis and treatment of HAPC has been rarely investigated. Here, the hypoxia‐induced HAPC model of rat is established, in which hemoglobin concentration significantly increases and platelets clearly decrease. The effect of resveratrol upon hypoxia enables HAPC remission and makes hemoglobin and platelet tend to a normal level. Furthermore, quantitative proteomics is applied to investigate the plasma proteome variation and the underlying molecular regulation during HAPC occurrence and treatment with resveratrol. Hypoxia promotes erythrocyte developing and differentiating and disrupts cytoskeleton organization. Notably, the resveratrol administration reverses the proteome change pattern due to hypoxia and contributes to plateau adaption. Quantitative verification of differentially expressed proteins confirms the roles of resveratrol in HAPC. Resveratrol is expected to be useful for HAPC treatment.