Relationship between human development and disappearance of unusually large von Willebrand factor multimers from plasma

von Willebrand factor (vWF) multimers were examined in fetal, umbilical cord, and neonatal platelet-poor plasma (PPP) specimens. Sixty-five of 65 (100%) fetal PPP samples aged less than 35 weeks and seven of ten (70%) fetal samples aged greater than 35 weeks had unusually large vWF (ULvWF) multimers. Thirty of 46 (65%) cord PPP samples from neonates ranging in gestational age from 34 to 41 weeks had ULvWF. There was no significant relationship between either gestational age at time of delivery or birth weight and likelihood of finding ULvWF multimers in cord PPP samples. No maternal PPP sample contained ULvWF multimers. Serial heelstick samples from 16 preterm and term neonates were analyzed for 8 weeks. ULvWF multimers disappeared from the PPP of ten of the neonates during this time. The PPP of four neonates had vWF patterns similar to those in normal adult PPP throughout the sampling period. The ULvWF multimeric forms of fetal and neonatal PPP samples were similar to those constitutively released from endothelial cells. They were not as slowly migrating in a very porous 0.5% agarose gel system as the ULvWF multimers released from Weibel-Palade bodies in response to the calcium ionophore A23187. A vWF protomer was present in 97% of fetal samples, 83% of cord blood specimens, and 11% of neonatal heelstick samples, but was not found in any maternal sample. These results indicate that control mechanisms operative in older children and adults to prevent circulation of ULvWF multimers and vWF protomeric forms are normally acquired late in uterine life or during the neonatal period. ULvWF multimers, which are normal components of fetal, most cord, and some neonatal plasma samples, may contribute to in utero and postnatal hemostasis.     

Thrombospondin from activated platelets promotes sickle erythrocyte adherence to human microvascular endothelium under physiologic flow: a potential role for platelet activation in sickle cell vaso-occlusion

Adherence of erythrocytes to vascular endothelium likely contributes to the pathophysiology of episodic vascular occlusion in patients with sickle cell disease (SCD). In addition, coagulation activation has been reported in sickle patients during complications such as pain episodes. To test the hypothesis that platelet activation contributes to sickle erythrocyte binding, we investigated whether factors released from activated sickle platelets promote adherence of sickle erythrocytes to human microvascular endothelial cells (MEC) under flow conditions. Activated sickle platelet supernatant (ASPS) promoted high levels of sickle erythrocyte adherence to MEC (55.4 +/- 3.9 erythrocytes/mm2) but only moderate adherence of normal erythrocytes to MEC (14.1 +/- 0.7 erythrocytes/mm2). When MEC were incubated with an antibody (OKM5) against CD36 (a thrombospondin [TSP] receptor), platelet supernatant mediated sickle erythrocyte adherence was inhibited 86%, suggesting that TSP participated in the adherence. To further define the role of TSP in adherence, additional studies using purified TSP were performed. At a concentration of 0.2 micrograms/mL TSP in serum-free media (SFM), sickle erythrocyte adherence to MEC was 33.9 +/- 2.7 erythrocytes/mm2 and sixfold greater than either sickle erythrocyte adherence in the absence of TSP or normal erythrocyte adherence in the presence of TSP. Doubling the concentration of TSP to 0.4 micrograms/mL proportionally increased adherence of sickle erythrocytes. Incubation of MEC with OKM5 or anti-alpha v monoclonal antibodies inhibited TSP-mediated sickle erythrocyte adherence more than 95%. These data suggest that activated platelet release factors, including alpha-granule TSP, which promote receptor-mediated sickle erythrocyte adherence to microvascular endothelium. Such factors released during in vivo platelet activation could contribute to vaso-occlusive complications by promoting erythrocyte adherence and microvascular occlusion.     

Basic fibroblast growth factor promotes the proliferation of human megakaryocyte progenitor cells

Basic fibroblast growth factor (bFGF), a multifunctional growth factor produced by bone marrow stromal cells, is known to be a potent modulator of hematopoiesis. Because bFGF is present in both human megakaryocytes (MKs) and platelets, we have hypothesized that this growth factor might affect human megakaryocytopoiesis. To test this hypothesis, either low density bone marrow (BM) cells (LDBM), a human BM subpopulation (CD34+ DR+) enriched for the colony-forming unit megakaryocyte (CFU-MK) or a BM subpopulation (CD34+ DR-) enriched for the more primitive burst-forming unit megakaryocyte (BFU-MK) were assayed in the presence of this growth factor. The effect of bFGF on MK colony formation differed according to the cell population assayed. bFGF alone had on MK colony-stimulating activity (MK-CSA) when either CD34+ DR+ or CD34+ DR- BM cells were cloned, but exhibited MK-CSA equivalent to that of interleukin-3 (IL-3) when LDBM cells were used as the target cell population. The MK-CSA of bFGF was inhibited by the addition of neutralizing antisera to either IL-3 and/or granulocyte- macrophage colony-stimulating factor (GM-CSF) but not IL-6. The addition of excess amounts of either IL-3 or GM-CSF to cultures containing bFGF plus anti-IL-3 or anti-GM-CSF reversed the inhibition by the corresponding antisera. The addition of bFGF and IL-3 to assays containing CD34+ DR+ or CD34+ DR- cells increased the size of both CFU- MK- and BFU-MK-derived colonies, respectively, when compared with assays containing IL-3 alone. This increase in MK colony size mediated by bFGF was not affected by addition of either an anti-GM-CSF or anti- IL-6 neutralizing antisera. When LDBM cells were assayed, bFGF alone increased CFU-MK-derived colony size when compared with control values. However, this potentiation of MK colony size by bFGF could be reversed by the addition of either anti-IL-3 or anti-GM-CSF but not anti-IL-6 antisera. In addition, the effects of bFGF and IL-3 on the size of MK colonies cloned from LDBM were not additive. These results suggest that bFGF affects human megakaryocytopoiesis by directly promoting MK progenitor cell proliferation and stimulating BM accessory cells to release growth factor(s) with MK-CSA, such as IL-3 and GM-CSF. We conclude that bFGF, likely produced by cellular components of the BM microenvironment, plays an important role in the control of human megakaryocytopoiesis.     

Treatment of Diamond-Blackfan anemia with recombinant human interleukin- 3 [see comments]

This report describes the response of eighteen Diamond-Blackfan anemia (DBA) patients to recombinant human interleukin-3 (rhIL-3). rhIL-3 was administered subcutaneously once daily on an escalating dose schedule (0.5 to 10 micrograms/kg/d). The rhIL-3 dose was escalated every 21 days until erythroid response was attained, grade III or IV nonhematologic toxicity was observed, or the maximum rhIL-3 dose was reached. Four patients experienced clinically significant erythroid responses. Two of the responders were steroid-dependent and transfusion- independent, while two were steroid-independent and transfusion- dependent. Baseline clinical or laboratory parameters, in particular in vitro bone marrow erythroid progenitor assays, were not useful in predicting rhIL-3 response. rhIL-3 administered at 5 to 10 micrograms/kg/d was associated with an increase in total white blood cell count, secondary to increases in neutrophils, eosinophils, and lymphocytes. Patients experienced a dose-dependent elevation in absolute eosinophils across the entire dose range. Two of the responding patients remain on maintenance rhIL-3, without diminution of effect at 244 and 370 + days. rhIL-3 was discontinued in the other two responders, because of the development of deep venous thrombi.     

A primary care register for impaired glucose handling (IGH): impact on cardiometabolic profile

ObjectiveDiet and exercise reduce the incidence of diabetes in high-risk individuals as does Metformin, although less dramatically. Here we evaluated if lifestyle and pharmacological intervention, for people at risk of diabetes, resulted in an improvement in their cardiometabolic risk profile.Research design/methodsIn a primary care based study, 92 individuals screened opportunistically and identified to have impaired glucose handling were offered detailed lifestyle advice, at 6 monthly intervals, with targeting of cardiovascular risk factors. Duration of follow-up was 4 years. The relation between fasting and 2 h glucose with different cardio-metabolic risk factors over time was assessed using multi-level modeling.ResultsThere was no significant weight reduction. At 24 months, mean fasting glucose level (6.4 mmol/L (95% CI 6.0–6.8)) was slightly lower than at baseline (6.6 mM (95% CI: 6.4–6.9), F = 3.67; p < 0.001). For men and women combined, systolic blood pressure (mean difference = ?6 mmHg, p = 0.013), total cholesterol (?0.66 mmol/L, p < 0.0001) and triglycerides (?0.13 mmol/L, p = 0.133) fell, whilst HDL-cholesterol (0.12 mmol/L, p = 0.047) rose. Diabetes developed in 18/92 participants during follow-up (up to 4 years).Five per cent of participants were started on Metformin, 88.5% on lipid lowering agents and 85.4% on anti-hypertensive agents. After adjusting for age, sex and BMI, 2 h glucose was independently and negatively associated with HDL-cholesterol (β = ?2.17, p = 0.041), and positively with systolic BP (β = 0.24, p = 0.004, per 5 mmHg).ConclusionsTargeted intervention had an effective role in improving lipid and BP profile in individuals with impaired glucose handling, with limited impact on glycaemia and no impact on weight. More work needs be done to evaluate the potential benefit of insulin sensitizing agents in this setting.     

心脏康复:心血管疾病二级预防的标准治疗(第二部分)

关于心脏康复是心血管疾病二级预防标准治疗的综述,第一部分我们已经阐述了心脏康复的概念、核心构成和益处,现将讨论心脏康复的实施方法、克服心脏康复实施过程中障碍的途径,以及其未来的发展方向。     

心脏康复:心血管疾病二级预防的标准治疗(第一部分)

尽管心血管疾病的诊断和急性事件的治疗得到了高度重视,但针对减少心血管事件反复再发的继续治疗即二级预防却没有得到应有的关注。过去的15年,心脏康复已经逐渐成为心血管疾病二级预防的一项标准治疗,持续不断的证据显示了心脏康复改善生活质量的诸多益处,在世界范围内心脏康复已经被包含在心血管疾病诊疗的临床实践指南中。尽管如此心脏康复并没有被充分应用,尤其在发展中国家。本综述主要描述心脏康复的基本概念、核心构成和相关益处。     

Type 1 diabetes in Cheshire: cardiometabolic risk factor trends (2004-2009)

AimsIn the context of changes in the last 10 years in treatment strategies for type 1 diabetes we evaluated longitudinal trends in cardiometabolic risk factor profiles in a population from North-West England.MethodsWe retrospectively examined longitudinal case records for the period for 291 adult patients followed up between 2004 and 2009 (age range 16–85). Data search was performed through the EMIS^® software provider using data held in primary care.ResultsLongitudinal analysis of individually followed patients indicated a mean 0.4% reduction in HbA1c from 8.3% (67 mmol/mol) at baseline (p = 0.002). The proportion of patients with an HbA1c ≥10% (86 mmol/mol) at baseline had a significant reduction over time from 14.0% to 9.5% (χ² = 9.4, p = 0.002). BMI remained unchanged (28.3 vs 28.4 kg/m²). However total cholesterol fell by 12.5% from 4.8 mM to 4.2 mM, (p < 0.0001) with a corresponding 23% reduction in LDL-cholesterol from 3.0 mm to 2.3 mM (p < 0.0001). There was a significant fall in diastolic BP (78–74 mmHg, p = 0.0016). In a mixed longitudinal regression model, HbA1c was associated with LDL-C (β = 0.28, p < 0.001) and age (β = 0.02, p = 0.001), independent of BMI, gender and systolic BP.DiscussionIn spite of intensive work to improve glycaemic control in type 1 diabetes, mean HbA1c remains above target for many people in our area, highlighting the difficulty of achieving glycaemic targets in type 1 diabetes. The significant reduction in diastolic BP, LDL and total cholesterol may have long-term benefit in cardiovascular event rate reduction.     

Discontinuation of Mycobacterium avium complex prophylaxis in patients with antiretroviral therapy-induced increases in CD4+ cell count. A randomized, double-blind, placebo-controlled trial. AIDS Clinical Trials Group 362 Study Team

BACKGROUND: Patients infected with HIV who experience increases in CD4(+) cell counts are at reduced risk for opportunistic infections. However, the safety of discontinuing prophylaxis against Mycobacterium avium complex has been uncertain. OBJECTIVE: To compare the rate of M. avium complex infection in patients with increased CD4(+) cell counts who receive azithromycin and those receiving placebo. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: 29 university-based clinical centers in the United States. PARTICIPANTS: 643 HIV-1-infected patients with a previous CD4(+) cell count less than 0.05 x 10(9) cells/L and a sustained increase to greater than 0.10 x 10(9) cells/L during antiretroviral therapy. INTERVENTION: Azithromycin, 1200 mg once weekly (n = 321), or matching placebo (n = 322). MEASUREMENTS: Mycobacterium avium complex cultures, CD4(+) cell counts, and clinical evaluations for AIDS-defining illnesses and bacterial infections were done every 8 weeks. Plasma HIV-1 RNA levels were measured at 16-week intervals. RESULTS: During follow-up (median, 16 months), 2 cases of M. avium complex infection were reported among the 321 patients assigned to placebo (incidence rate, 0.5 event per 100 person-years [95% CI, 0.06 to 1.83 events per 100 person-years]) compared with no cases among the 322 patients assigned to azithromycin (CI, 0 to 0.92 events per 100 person-years), resulting in a treatment difference of 0.5 event per 100 person-years (CI, -0.20 to 1.21 events per 100 person-years) for placebo versus azithromycin. Both cases were atypical in that M. avium complex was localized to the vertebral spine. Patients receiving azithromycin were more likely than those receiving placebo to discontinue treatment with the study drug permanently because of adverse events (8% vs. 2%; hazard ratio, 0.24 [CI, 0.10 to 0.57]). CONCLUSIONS: Prophylaxis against Mycobacterium avium complex can safely be withdrawn or withheld in adults with HIV infection who experience increases in CD4(+) cell count while receiving antiretroviral therapy.