Characterization of the p67phox gene: genomic organization and restriction fragment length polymorphism analysis for prenatal diagnosis in chronic granulomatous disease

The genetic defect in the p67phox-deficient form of chronic granulomatous disease (CGD) follows an autosomal recessive pattern of inheritance. When genomic DNA from normal individuals is digested with HindIII and probed with p67phox cDNA an allelic restriction fragment length polymorphism (RFLP) of 4.0 kb or 2.3 kb is detected. We cloned and characterized the p67phox gene using the cDNA and sequenced the exon/intron boundaries, mapping 16 exons on the 40-kb gene. The polymorphic region was then sequenced to identify the inheritance pattern of amniocentesis-derived fetal cells by genomic amplification. The proband, a 9-year-old female patient with p67phox-deficient CGD, and her phenotypically normal mother are homozygous for the RFLP marker, whereas the father and two brothers are heterozygous. The fetus was shown to be heterozygous as well, showing it had inherited at least one normal p67phox gene from the father and that it was predicted to have a normal phenotype. Cord blood samples at birth showed normal oxidative function. Amplification allows rapid detection of the inheritance pattern for fetal diagnosis in informative families. We report the genomic structure of p67phox and an amplification-based method for detection of the marker on chromosome 1q25, used here for prenatal diagnosis of CGD.     

Optic disc haemorrhages and vascular abnormalities in a glaucoma population

Purpose: To retrospectively examine the optic disc photographs of a glaucoma population for optic disc haemorrhages, vascular occlusions and vascular abnormalities. Methods: The optic disc photographs of 906 eyes of glaucoma and suspect glaucoma patients were examined. Optic disc photographs were taken annually, where possible, with the follow-up period varying between 1 and 14 years duration (mean, 2.89). Glaucoma patients are regularly reviewed every 4–6 months and glaucoma suspects every 1–2 years, depending on the ophthalmologist. Low-tension glaucoma patients were reviewed more frequently (mean, every 2.6 months). The results of the findings were compared to a control group of 39 subjects with a mean follow-up period of 7 years, using Fisher's exact test. Results: It was found that during the period under review, 7.4% (n= 67) of eyes had optic disc haemorrhages. The highest frequency of optic disc haemorrhages (37.5%) was found in the low tension glaucoma group (P= 0.0001) followed by 11.4% of primary open-angle glaucoma eyes (P= 0.03). In the normal group there were three eyes with optic disc haemorrhages and one with a disc collateral, which constitutes 5.1% vascular changes in this sub-group. Of the study eyes 2.8% had central retinal vein occlusions, 1.3% branch vein occlusion, 1.2% disc vessel abnormalities (loops) and 1.1% disc collaterals. Discrete nerve fibre layer haemorrhages and microaneurysms were found in 0.8% and 1.8% of eyes, respectively. Conclusions: A total of 16.8% of the eyes observed in this study had either disc haemorrhages or vascular changes. The underlying trend of vascular and haemorrhagic changes in glaucoma are demonstrated in this sample, which is in general agreement with previous studies. The high percentage of optic disc haemorrhages in low tension glaucoma is highlighted. The presence of microaneurysms and nerve fibre layer haemorrhages is interesting but of unknown significance.     

重庆居民与流动人口结核病就诊及诊断的延迟因素：隐蔽性调查分析

目的:调查重庆居民及流动人口结核病就诊及诊断延迟情况,探索在其过程中存在的问题,分析问题产生的原因。方法:在重庆市主城区按照经济发展水平的不同选取了两个区Y和J,采用方便抽样的方法在Y区抽取了一家综合性医院的呼吸科门诊R,在J区抽取了一家综合性医院的一般基层门诊P,于2005-10-10/14和2005-10-17/21,采用隐蔽性观察法对门诊情况进行了观察,主要观察医生和患者的相关语言、行为,了解结核病就诊及诊断延迟情况。实验得到了利物浦大学热带医学院伦理委员会的许可,并通过了重庆市卫生局的批准。资料分析采用主题框架分析法。结果:重庆居民和流动人口都存在结核病就诊延迟的情况,主要与患者的经济状况、健康意识和社会支持等因素有关;医院在结核病的诊断方面具备基本的技术和条件,诊断延迟则主要与医务人员对结核病的意识和责任心有关;另外患者自身在诊疗过程中的中途退出现象不容忽视,也是导致延迟的一个重要因素。结论:一方面综合医院缺乏对结核病患者的管理措施和意识,对结核患者重治轻管,另一方面特殊人群的患者卫生保健支付能力差,缺乏相关结核病防控知识,应依据目前的形势对相关领域进行政策倾斜和调控,积极开展对人群行之有效的健康教育。     

Effect of calcium ion concentration on the ability of fibrinogen and von Willebrand factor to support the ADP-induced aggregation of human platelets

To investigate the suggestion that von Willebrand factor (vWf) can substitute for fibrinogen in supporting ADP-induced aggregation of human platelets, we studied platelet reactions in two media: (1) a high calcium medium, Tyrode-albumin solution containing calcium ions in the physiological range of 2 mmol/L, and (2) a low calcium medium, modified Tyrode-albumin solution from which calcium salt was omitted (calcium ion concentration approximately 20 mumol/L). In the high calcium medium vWf even at concentrations up to six times as high as physiological, showed little or no potentiation of ADP-induced platelet aggregation, whereas fibrinogen strongly potentiated reversible aggregation without thromboxane formation or release of granule contents. In the low calcium medium, either vWf or fibrinogen supported biphasic aggregation in response to ADP, with thromboxane formation and release of granule contents. Aspirin and the thromboxane receptor blocker BM 13.177 inhibited these secondary responses to von Willebrand factor, indicating that they require thromboxane A2 formation and feedback amplification by thromboxane A2. A monoclonal antibody, 10E5, to the platelet glycoprotein IIb/IIIa complex inhibited both primary and secondary aggregation. Although vWf supports ADP-induced aggregation when the concentration of ionized calcium is in the micromolar range, it does not support ADP-induced aggregation in the presence of a concentration of ionized calcium in the physiological range, indicating that vWf probably cannot substitute for fibrinogen in supporting ADP- induced aggregation in vivo.     

F reticulocyte response in sickle cell anemia treated with recombinant human erythropoietin: a double-blind study

Studies on baboons and preliminary observations in three patients with sickle cell anemia (SS) suggested that high doses of pulse administered recombinant human erythropoietin (rHuEPO) stimulate F-reticulocyte production. We now report on the administration of rHuEPO in a double- blind format to ascertain frequency of response and potential precipitation of side effects. Ten patients were enrolled, but one was discontinued due to the indication of a blood transfusion. Of the other nine, five received rHuEPO in escalating doses (from 400 to 1,500 U per kg twice daily [BID] per week), alternating with a placebo, in blinded fashion. The second group, consisting of four patients, followed an identical protocol (except starting dose was 1,000 U/Kg, BID per week) and were iron supplemented during treatment. The criterion of response was a transient doubling (as a minimum) of the steady-state F- reticulocyte level. We found that none of the five patients in the first group responded to rHuEPO, and two of them became iron deficient, as judged by a significant decrease in ferritin. Of the second group, four patients responded with F-reticulocyte increases. In three patients, open label administration of rHuEPO confirmed the effect. We observed seven painful episodes during this study, two during the EPO administration and five during the placebo arm. Three patients were phlebotomized because the hemoglobin level increased 1.5 g/dL more than steady-state levels. Of the six patients followed-up by percent dense cell determinations, one exhibited increased levels during periods of the treatment, whereas the other five showed no change. No anti-rHuEPO antibodies were detected. We conclude that rHuEPO can stimulate F- reticulocyte response in some patients with sickle cell anemia, without apparent negative clinical side effects. The state of iron stores may be critical. Whether higher doses of rHuEPO and/or a different regimen might induce sustained F cells and fetal hemoglobin increases remains to be determined.     

Comparison of thrombin and ristocetin in the interaction between von Willebrand factor and platelets

It is known that the antibiotic ristocetin exposes the platelet membrane receptor for factor VIII/von Willebrand glycoprotein (FVIII/vWF). Recent reports suggest that low concentrations of thrombin also cause platelet membrane receptors to become available for FVIII/vWF. As a consequence, the suspicion has been raised that thrombin provides similar or equivalent activity in vivo to that observed for ristocetin under in vitro conditions. In this study, we quantitated the extent to which thrombin promotes the binding of FVII/vWF to platelets and determined whether or not this interaction initiates or complements platelet aggregation. With ristocetin present, the amount of 125I-FVIII/vWF that became platelet-bound correlated closely with the onset, rate, and extent of platelet aggregation. In contrast, at every thrombin concentration tested, the amount of 125I- FVIII/vWF that specifically bound to platelets was about 6% of that observed with ristocetin. Significantly, FVIII/vWF did not augment the rate of aggregation of platelets in response to thrombin or initiate platelet aggregation when subaggregating doses of thrombin were used. These observations indicate that the minimal association that occurs between FVIII/vWF and the platelet membrane in the presence of thrombin does not correlate with platelet aggregation and therefore is not analogous to the effects of ristocetin. Whether the low level of binding relates to another process, such as platelet-endothelial interactions, remains unknown.     

The inhibitory effects of exogenous arachidonic acid on rabbit platelet aggregation and the release reaction

Although arachidonic acid causes rabbit platelet aggregation and the release of granule contents in suspensions of washed platelets when used in concentrations of approximately 50-300 microM, higher concentrations (500 microM) cause neither aggregation nor release. Suspensions of platelets from rabbits wee exposed to arachidonic acid (250 microM) for 15 min, allowed to recover in the presence of PGE1 for 30 min, washed, and resuspended; in some experiments, the platelets were treated with aspirin before being exposed to arachidonic acid. Aggregation of platelets pretreated with arachidonic acid was inhibited in response to ADP; this effect was greater with the non-aspirin- treated platelets and persisted for at least 4 hr after resuspension. The association of 125I-fibrinogen with the platelets as a result of ADP stimulation was also inhibited. Aggregation and release of granule contents in response to collagen and low concentrations of thrombin was inhibited, but the inhibition could be overcome by higher concentrations. Thrombin induced further release of granule contents from platelets exposed to arachidonic acid without pretreatment with aspirin. Platelets that had been exposed to arachidonic acid, either with or without pretreatment with aspirin, did not aggregate or undergo further release upon stimulation with arachidonic acid after they were washed and resuspended. Inhibition of the lipoxygenase pathway with eicosatetraynoic acid (ETYA) or nordihydroguaiaretic acid (NDGA) did not affect the inhibition caused by arachidonic acid, so it is unlikely that a product of this pathway is responsible for the inhibition. Mixing experiments indicated that the pretreated platelets did not form a thromboxane-A2-like activity, and that they were unresponsive to aggregation and release induced by products formed from arachidonic acid. Experiments with 3H-arachidonic acid showed that after 45 min of incubation with platelets, only 1.1% of the 3H-arachidonic acid remained as free arachidonic acid in the platelets. Although cyclic-AMP was slightly increased 1 min after the addition of arachidonic acid, the cyclic-AMP concentration was the same as that of control platelets after the platelets were washed and resuspended, indicating that increased cyclic-AMP is not likely to be responsible for the persistent inhibitory effect. Thus, the inhibitory effect of pretreatment with arachidonic acid is a general effect on responses to a variety of aggregating agents that act through different mechanisms, and the inhibition is not related to thromboxane-A2 formation. The possibility of membrane perturbation resulting in the unavailability of receptors may explain the persistent inhibitory effect, but the responsible reactions have not been identified.