The range of minimum provoking doses in hazelnut-allergic patients as determined by double-blind, placebo-controlled food challenges

BACKGROUND: The risk for allergic reactions depends on the sensitivity of individuals and the quantities of offending food ingested. The sensitivity varies among allergic individuals, as does the threshold dose of a food allergen capable of inducing an allergic reaction. OBJECTIVE: This study aimed at determining the distribution of minimum provoking doses of hazelnut in a hazelnut-allergic population. METHODS: Thirty-one patients with a history of hazelnut-related allergic symptoms, a positive skin prick test to hazelnut and/or an elevated specific IgE level, were included. Double-blind, placebo-controlled food challenges (DBPCFC) were performed with seven increasing doses of dried hazelnut (1 mg to 1 g hazelnut protein) randomly interspersed with seven placebo doses. RESULTS: Twenty-nine patients had a positive challenge. Itching of the oral cavity and/or lips was the first symptom in all cases. Additional gastrointestinal symptoms were reported in five patients and difficulty in swallowing in one patient. Lip swelling was observed in two patients, followed by generalized urticaria in one of these. Threshold doses for eliciting subjective reactions varied from a dose of 1 mg up to 100 mg hazelnut protein (equivalent to 6.4-640 mg hazelnut meal). Extrapolation of the dose-response curve showed that 50% of our hazelnut-allergic population will suffer from an allergic reaction after ingestion of 6 mg (95% CI, 2-11 mg) of hazelnut protein. Objective symptoms were observed in two patients after 1 and 1,000 mg, respectively. CONCLUSION: DBPCFCs demonstrated threshold doses in half of the hazelnut-allergic patients similar to doses previously described to be hidden in consumer products. This stresses the need for careful labelling and strategies to prevent and detect contamination of food products with hazelnut residues.     

Prediction of steady state bioequivalence relationships using single dose data II-nonlinear kinetics

Two nonlinear pharmacokinetic models were simulated to investigate the relationship between single and multiple dose bioequivalency parameters for drugs such as phenytoin and propranolol which exhibit either saturable elimination kinetics or a capacity limited first pass effect. Mean Tmax, Cmax and area under the plasma-concentration time curve values from 0 to infinity (AUC 0-infinity) were compared after a single and multiple dose(s) of a test or reference drug. The aim was to determine if there were systematic changes in the limits of the single dose confidence interval at steady state that would limit the usefulness of confidence intervals following a single dose in accurately predicting bioavailability following multiple dosing. The 90 per cent confidence interval expressed as a percentage of the reference mean for Tmax, Cmax, and AUC 0-infinity showed model dependent changes from single to multiple dosing in response to the level of data error and changes in absorption. Changes in clearance also seemed to have a marked effect on the observed limits of the single and multiple dose confidence intervals especially for Cmax which showed a characteristic change in the intervals as a function of the clearance ratio. The model used to describe phenytoin had confidence intervals for Cmax and AUC 0-infinity from single to multiple dosing that were similar to that seen for the experimental data. However, the model predictions for Tmax confidence intervals following single and multiple dosing was at variance with the experimental data for formulations A and B.     

小剂量低LET辐射对人淋巴细胞SCE的影响

本文用磷酸盐Giemsa法观察了小剂量X射线照射对人离体外周血淋巴细胞SCE的影响。其结果照射组各剂量点均不明显地高于对照组,证实了SCE对电离辐射不敏感,说明染色体结构畸变和SCE的发生是彼此独立的两个不同事件。     

电子直线加速器照射对NIH 3T3细胞的细胞周期及凋亡的影响

目的 探讨电子直线加速器照射对细胞周期及细胞凋亡的影响。方法 采用直线加速器对NIH 3T3细胞进行照射，观察细胞周期及细胞凋亡的改变情况；同时测定损伤前后p53蛋白的表达情况。结果 照射后细胞凋亡数增加，p53蛋白表达量上升。结论 电子直线加速器照射损伤可诱导细胞凋亡。     

E838等抗放药对放射损伤防治作用的比较

目的；比较研究E838，WR－2721，盐酸胱胺和炔雌醇等对放射损伤的防治作用及其相互之间的协同作用关系。方法：采用小鼠腹腔注射或灌胃的方法在致伤前或／和致伤后按常用量给药，观察30d存活率，死亡动物平活日和保护系数K的差异。结果：（1）致伤前预防给药，上述4种药物均明显提高了放射损伤的存活率，并延长了死亡动物的平均存活日，其中以E838和WR2721效果最佳；（2）致伤后给药则仅E838和茜草显示了治疗效果；（3）联合用药实验显示所研究的5种配伍用药方式均有较好的防治效果，但以WR2721（防）＋E838（治）效果最好。结论：E838和WR2721与其它抗放药相比具有较理想的辐射防护作用，且E838还有一定的治疗作用,两者合理配伍使用可发挥协同的作用效果。     

The Treatment of Low Grade Cerebral Astrocytomas by Radiotherapy in Queensland

The records of 108 adult patients with supratentorial low grade astrocytoma presenting between 1/1/80 and 31/12/87 were examined for the following factors which might affect survival: patient age, extent of surgical resection, site of tumour, tumour grade, radiation field size and radiation dose. Univariate analysis showed that patient age, field size and radiation dose were significant prognostic factors, but with multivariate analysis only patient age and radiation field size were significant independent variables. It is possible that field size is a proxy variable for tumour size.     

Prediction of steady-state bioequivalence relationships using single dose data I-linear kinetics

Simulated data using a linear one- and two-compartment body model with different absorption characteristics were used to evaluate the ability of single dose bioavailability data to predict the relationships that exist at steady state. This was done by comparing the confidence intervals obtained from single and multiple dose data sets for the parameters of Tmax, Cmax, and area under the curve from time zero to infinity (AUC0-infinity). As a consequence of Tmax and Cmax decreasing and increasing from single to multiple dosing regimens, the confidence intervals for these parameters reflected these changes. The 90 per cent confidence interval expressed as a percentage of the reference mean increased or decreased for Tmax dependent upon the ratio of Ka test/Ka reference, and decreased for Cmax while the interval for AUC0-infinity exhibited no predictable pattern and appeared to be influenced by the amount of error in the data set. Alteration of either the dosing interval or the fraction absorbed did not affect the pattern of change in the confidence intervals for Tmax and Cmax, but the latter did result in a decrease in the interval for AUC0-infinity. Analysis of the confidence intervals for Tmax, Cmax and AUC0-infinity in bioequivalency studies for quinidine gluconate and procainamide hydrochloride following administration of single and multiple doses to different subjects appeared to be consistent with the patterns observed for the simulated data sets.     

优化CT扫描参数,降低患者辐射剂量

CT检查中如何有效减少辐射剂量,保护患者,同时保证图像质量,作为从事放射的工作人员应该充分认识。本文从CT检查辐射剂量、优化参数及降低CT检查辐射剂量的途径等方面加以综述。     

非放射科护理人员医用放射线防护知识调查分析

目的：调查非放射科护理人员对医用放射线防护知识的掌握程度，并比较不同学历护理人员之间的差异，为提高临床护理人员的防护意识、制定具体防护措施提供理论依据。方法：采用自行设计的问卷对100名非放射科护理人员进行问卷调查．结果：非放射科护理人员对医用放射线防护知识缺乏，不同学历护理人员之间存在差异具有非常显著性（P〈0．05）。结论：对非放射科护理人员进行放射线防护知识普及势在必行，对保护患者及护理人员自身健康具有重要意义。