A method for calculating the mean absorption time of drugs undergoing reversible and first-pass metabolism

A method has been derived for calculating the mean absorption time of an oral drug and its interconversion metabolite which is generated from the drug systemically and presystemically. The method evolves from the convolution integral and requires plasma AUC and AUMC values after separate intravenous administration of the drug and its interconversion metabolite and oral administration of the drug. It can also be used to calculate the mean input time of a drug undergoing reversible metabolism and administered by any other extravascular route. Results of a simulation study using both errorless and errant data indicate that, when the absorption rate constant of a drug or its interconversion metabolite is not much larger than the apparent elimination rate constant, the proposed method performs satisfactorily. However, when the absorption rate constant of a drug or its interconversion metabolite is much larger than the apparent elimination rate constant, the proposed method appears to be inaccurate.     

可逆性胆碱酯酶抑制剂的研究:2-氧化-1,3,2-二氧磷杂环己烷类化合物的合成

本文报道2-氧化-1,3,2-二氧磷杂环己烷类衍生物的合成,希望寻找效果较好的可逆性胆碱酯酶抑制剂。初步药理实验证明,所合成的大部分化合物具有一定的抑制乙酰胆碱酯酶的作用,且毒性较低。通过对中间体Ⅱ进行质谱分析,发现该类化合物中大部分存在M-57碎片离子峰,利用高分辨质谱和亚稳离子测定,确定了该碎片离子的生成过程。     

Rest thallium-201 myocardial perfusion imaging in a patient with leukaemic infiltration of the heart

Despite the high incidence of leukaemic infiltration of the heart, only 8 cases of atrioventricular block due to leukaemia have been reported in the literature. Improvement in the heart block associated with disappearance of the leukaemic infiltrate has not been reported. A rest thallium-201 study was used in a 65-year-old man to demonstrate leukaemic infiltration of the heart which was associated with complete heart block. After chemotherapy, when the tumour burden was reduced and the leukaemia in remission, his heart block resolved, and a follow-up thallium scan was normal. Offprint requests to: A.C. Civelek     

Reversible inactivation of macaque frontal eye field

 The macaque frontal eye field (FEF) is involved in the generation of saccadic eye movements and fixations. To better understand the role of the FEF, we reversibly inactivated a portion of it while a monkey made saccades and fixations in response to visual stimuli. Lidocaine was infused into a FEF and neural inactivation was monitored with a nearby microelectrode. We used two saccadic tasks. In the delay task, a target was presented and then extinguished, but the monkey was not allowed to make a saccade to its location until a cue to move was given. In the step task, the monkey was allowed to look at a target as soon as it appeared. During FEF inactivation, monkeys were severely impaired at making saccades to locations of extinguished contralateral targets in the delay task. They were similarly impaired at making saccades to locations of contralateral targets in the step task if the target was flashed for ≤100 ms, such that it was gone before the saccade was initiated. Deficits included increases in saccadic latency, increases in saccadic error, and increases in the frequency of trials in which a saccade was not made. We varied the initial fixation location and found that the impairment specifically affected contraversive saccades rather than affecting all saccades made into head-centered contralateral space. Monkeys were impaired only slightly at making saccades to contralateral targets in the step task if the target duration was 1000 ms, such that the target was present during the saccade: latency increased, but increases in saccadic error were mild and increases in the frequency of trials in which a saccade was not made were insignificant. During FEF inactivation there usually was a direct correlation between the latency and the error of saccades made in response to contralateral targets. In the delay task, FEF inactivation increased the frequency of making premature saccades to ipsilateral targets. FEF inactivation had inconsistent and mild effects on saccadic peak velocity. FEF inactivation caused impairments in the ability to fixate lights steadily in contralateral space. FEF inactivation always caused an ipsiversive deviation of the eyes in darkness. In summary, our results suggest that the FEF plays major roles in (1) generating contraversive saccades to locations of extinguished or flashed targets, (2) maintaining contralateral fixations, and (3) suppressing inappropriate ipsiversive saccades. Received: 2 February 1996 / Accepted: 26 February 1997     

准分子激光原位角膜磨镶术后并发角膜瓣移位的原因分析及护理对策

原位角膜磨镶术(laser in situ kemtomileus,LASIK)是当今国际眼科界最常见的屈光角膜手术.随着LASIK手术越来越多地应用于临床,角膜瓣的并发症随之而来.文献报道[1],LASIK术后并发症发生率为3.4％～11.8％,而术中有关角膜瓣的发生率为0.5％～2％.角膜瓣一旦发生移位,会影响手术效果和视力恢复,须立即处理,否则后果严重[2].我们回顾性分析1 720例LASIK术后15例发生角膜瓣移位的患者资料,并对其护理策略进行探讨.     

Nelarabine-associated reversible Guillain-Barré–like syndrome or myelopathy in an adult patient with primary refractory T-lymphoblastic lymphoma

Nelarabine is a purine analogue used for the treatment of patients with relapsed or refractory T-cell acute lymphoblastic leukemia and T-cell lymphoblastic lymphoma mainly as a bridge to stem cell transplantation. The water-soluble prodrug of 9-beta-D-arabinofuranosyl guanine (Ara-G) is phosphorylated within leukemic cells to form ara-G triphosphate (ara-GTP), which terminates DNA chain elongation, resulting in cell death. The drug received accelerated approval by the US Food and Drug Administration (FDA) on October 2005 based on the induction of complete remissions in 2 phase II trials. In these trials, neurologic toxicity was mainly presented as peripheral neuropathy and, since, is a commonly reported side effect of the drug. However, cases of severe grade III, IV, or even fatal neurotoxicity as well as cases of ascending myelopathy have also been reported with most of these cases being irreversible. In this article, we report a reversible grade IV Guillain-Barré–like case of a patient with primary refractory T-cell lymphoblastic lymphoma treated with nelarabine. Guillain-Barré-like syndrome in this patient coexisted with toxic myelopathy which affected the whole spine. The pathogenetic mechanisms and genetic predisposition for nelarabine-associated neurotoxicity is still unknown. The role of the immune system and the patient’s genetic background are under investigation along with considerations on the right treatment of the syndrome. Gaining a better understanding in the contributing mechanisms will help us to recognize individuals in danger for neurotoxicity and will lead to the prompt treatment of this complication. Yet, it can be concluded from the present case and literature review that high-dose cytarabine regimens and intrathecal installations should be avoided in close time proximity with nelarabine treatment, as they could enhance neurotoxicity.