Characterization of autoantigenic epitopes on platelet glycoprotein IIb/IIIa using random peptide libraries

Most patients with chronic immune thrombocytopenic purpura (ITP) have autoantibodies directed against the glycoprotein (GP) IIb/IIIa complex. We have used a filamentous phage library that displays random linear hexapeptides to identify peptide sequences recognized by these autoantibodies. Plasma antibody eluates from two patients were used to select for phage displaying autoantibody-reactive peptides. From patient ITP-1 (known to have two distinct autoantibodies), we identified anti-GPIIb/IIIa antibody-specific phage encoding the peptide sequences Arg-Glu-Lys-Ala-Lys-Trp (REKAKW) and Pro-Val-Val-Trp-Lys-Asn (PVVWKN). Patient ITP-2 bound phage encoding the hexapeptide sequence Arg-Glu-Leu-Leu-Lys-Met. Each phage showed saturable dose-dependent binding to immobilized autoantibody, and binding could be blocked with purified GPIIb/IIIa. Patient ITP-1 autoantibody recognition of phage encoding REKAKW could be blocked with a synthetic peptide derived from the GPIIIa cytoplasmic tail; however, the PVVWKN was not. Using sequential overlapping peptides from the GPIIIa cytoplasmic region, an epitope for ITP-1 was localized to the sequence Arg-Ala-Arg-Ala-Lys-Trp (GPIIIa 734-739). Inhibition studies using synthetic peptides showed that phage REKAKW and PVVWKN were recognized by distinct autoantibodies from patient ITP-1. To determine whether individual patients with ITP possessed autoantibodies that recognize similar antigenic determinants on GPIIb/IIIa, the three phage were tested for binding to five other ITP patient autoantibodies. The phage encoding the peptide PVVWKN was found to bind ITP-1 and one other patient autoantibody. This result suggests that ITP patients recognize a limited number of shared epitopes.     

儿童癌症幸存者成年后的慢性疾病

由于治疗方法的进步,近80%的儿童和青少年癌症患者能够长期生存。在美国,约有270000例儿童癌症的幸存者,即每640名20至39岁成年人中就有一名幸存者。大量的幸存者有利于儿童癌症治疗后长期健康结果的研究。现在可以明确的是,化疗和放疗所致的儿童各器官系统损害在临床上可能潜伏多年。为了全面了解治疗儿童癌症而继发的健康问题,重要的是衡量三项长期结果:健康状况、死亡率和患病率。这三项中,关于前两项已有相当好的研究报道。在一项对20227例癌症5年生存者的回顾性分析中,Mertens等发现以下原因导致的超额死亡率具有统计学意义:继发癌症(…     

Premature or Just Small? Training Guatemalan Birth Attendants to Weigh and Assess Gestational Age of Newborns: An Analysis of Outcomes

We describe Guatemalan birth attendants’ identification of vulnerable newborns, their evaluation of gestational age and anthropometry, and the validity of the Capurro and New Ballard newborn gestational age assessment methods. We interviewed 49 birth attendants and trained 10 of these women to assess 63 newborns. The Capurro and Ballard methods were correlated (Spearman rho = .75, p < .001) and showed agreement (Bland-Altman plot, difference and bias, ?0.33 ± 1.3 weeks). Prematurity was estimated at 27% (Ballard) and 24% (Capurro); low birth weight (LBW) was 30%. Capurro provided a simplified, equivalent estimate of gestational age compared with New Ballard that could be used by birth attendants.     

Repeatability of near visual acuity measurement at high and low contrast

Purpose: The aim of this study was to determine the repeatability of high‐ and low‐contrast visual acuity (VA) measurements at near. Methods: Fifty‐five normal subjects were recruited. Inclusion criteria included visual acuity of at least 0.00 logarithm of minimum angle of resolution (logMAR) on each eye at distance. One eye was selected for this study, either the one with a better acuity or randomly chosen if there was no difference between the two eyes. Near VA was measured in a random order with the PolyU high‐contrast (PolyU‐HC), the PolyU low‐contrast (PolyU‐LC), the Precision high‐contrast (P‐HC) and the Precision low‐contrast (P‐LC) charts at 400 mm. Measurements were repeated after one to two weeks. Repeatability was presented using the 95% limits of agreement between visits. Results: The between‐visit repeatability was ±0.063 logMAR for high‐contrast and ±0.141 for low‐contrast using the PolyU charts. The between‐visit repeatability was ±0.120 logMAR for high‐contrast and ±0.110 for low‐contrast using the Precision charts. Seventeen subjects had high‐contrast VA better than ‐0.10 logMAR using Precision chart, which could not be measured by PolyU chart. The mean difference between high‐ and low‐contrast VA was 0.108 from the Precision charts (median difference of 0.10 or one line). Conclusions: The Precision charts could measure high‐contrast near VA to threshold level. Practitioners should be aware of a VA difference of more than one line in repetitive measurement, at both high and low contrast. A difference in near high‐ and low‐contrast VA of more than one line may warrant further investigation.     

Depsides as non-redox inhibitors of leukotriene B(4) biosynthesis and HaCaT cell growth, 2. Novel analogues of obtusatic acid

Aseries of obtusatic acid analogues has been synthesized and evaluated as inhibitors of leukotriene B(4) (LTB(4)) biosynthesis and as antiproliferative agents. The 4-O-benzylated and the 4-O-demethylated congeners were the most potent inhibitors of LTB(4) production of the depside class of compounds, with IC(50) values in the submicromolar range. Furthermore, these compounds do not function as redox-based inhibitors because they were not reactive against a stable free radical, 2,2-diphenyl-1-picrylhydrazyl, and did not produce appreciable amounts of deoxyribose degradation as a measure of their potency to generate hydroxyl radicals. Some obtusatic acid congeners were also potent inhibitors of keratinocyte growth. Growth inhibition was not mediated by damage to the cell membrane, as the activity of lactate dehydrogenase released from the cytoplasm was in the control range.     

Dofetilide for Atrial Arrhythmias in Congenital Heart Disease: A Multicenter Study

Background: Very little is known about use of the class III antiarrhythmic dofetilide in patients with congenital heart disease (CHD).
Methods: A multicenter retrospective review of experience with dofetilide in CHD patients was undertaken.
Results: Twenty adults with CHD and refractory atrial arrhythmias were treated with dofetilide at four institutions over a 7-year period. Three (15%) experienced adverse effects during in-hospital initiation of dofetilide (two with torsade de pointes, one with excessive QTc prolongation) and were not continued on this therapy. The remaining 17 were discharged taking dofetilide, with either resolved or improved arrhythmia. One was lost to follow-up. Five subsequently discontinued dofetilide due to waning effectiveness, manifest by recurrence of their arrhythmias. Eleven (55%) remained on dofetilide at most recent visit, with a median follow-up of nearly 1 year. Seven of these 11, or 35% of the CHD patients originally started on dofetilide, experienced a complete resolution of their arrhythmia. The remaining four had breakthrough episodes of atrial arrhythmia, but remained on dofetilide. No patient experienced torsade de pointes after the in-hospital initiation period.
Conclusions: Used appropriately, dofetilide appears to be a viable adjunct to catheter-based ablation and alternative pharmacological approaches for the treatment of atrial arrhythmias in adult patients with congenital heart disease.     

Stenosis of the vena cava: preliminary assessment of treatment with expandable metallic stents

To test the ability of Gianturco expandable metallic stents to dilate and maintain patency in stenotic venae cavae, stenosis of the inferior vena cava was created in seven mongrel dogs by the percutaneous injection of absolute ethanol into the paravascular retroperitoneal space. Gianturco stents, placed across the stenotic segment, resulted in successful dilatation with improved hemodynamics in four dogs. The stents failed to dilate an occluded vena cava in one dog; in the remaining dogs, stent placement was complicated by early migration and occlusion. Gianturco stents were placed in two patients, one with superior vena cava syndrome and one with retroperitoneal fibrosis that obstructed the inferior vena cava, and resulted in immediate relief of presenting symptoms. These results should be viewed cautiously, but further investigation into the clinical use of the stents is indicated, especially for patients for whom other treatments are difficult.     

Precise intraoperative location of gastrointestinal bleeding with a hand-held counter. Work in progress

The nuclear medicine bleeding scan is frequently insufficient to locate sites of bleeding precisely, in spite of its great sensitivity. A small, hand-held Geiger-Müller counter, placed directly on exposed intestine in the operating room, enables precise location of the probable bleeding site. In three patients, the technique allowed a minimal amount of intestine to be resected, distinguished between large- and small-intestinal hemorrhage, and eliminated other foci as sites of bleeding.