正交实验设计优化石墨炉原子吸收法测定尿锰实验条件的探讨

目的选择石墨炉原子吸收光谱法测定尿中锰的最佳实验条件,建立尿中锰的测定方法。方法应用L16（4^4）正交表安排石墨炉原子吸收光谱法测定尿锰时的灰化温度、灰化时间、原子化温度和原子化时间并进行实验,优化各项仪器操作参数,考察灰化温度、原子化温度及各项分析性能指标,包括准确度、精密度、检出限、特征质量,建立测定尿中锰的方法。结果石墨炉原子吸收光谱法测定尿锰的最佳条件：是灰化温度和原子化温度分别为1300和2400℃,灰化时间和原子化时间分别为8和12S。分别测定高中低加标样的相对标准偏差RSD值（n=6）在2．12％～5．98％之间,样品加标回收率在96．7％-99．6％之间,检出限为0．17斗g／L,特征质量为1．78pg。结论利用正交实验设计优化实验条件可以提高工作质量和效率,所建立的分析方法准确、灵敏、简便,完全符合尿中锰的测定要求。     

A comparative study of validated spectrophotometric and TLC- spectrodensitometric methods for the determination of sodium cromoglicate and fluorometholone in ophthalmic solution

The determination of sodium cromoglicate (SCG) and fluorometholone (FLU) in ophthalmic solution was developed by simple, sensitive and precise methods. Three spectrophotometric methods were applied: absorptivity factor (a-Factor method), absorption factor (AFM) and mean centering of ratio spectra (MCR). The linearity ranges of SCG were found to be (2.5–35 μg/mL) for (a-Factor method) and (MCR); while for (AFM), it was found to be (7.5–50 μg/mL). The linearity ranges of FLU were found to be (4–16 μg/mL) for (a-Factor method) and (AFM); while for (MCR), it was found to be (2–16 μg/mL). The mean percentage recoveries/RSD for SCG were found to be 100.31/0.90, 100.23/0.57 and 100.43/1.21; while for FLU, they were found to be 100.11/0.56, 99.97/0.35 and 99.94/0.88 using (a-Factor method), (AFM) and (MCR), respectively. A TLC-spectrodensitometric method was developed by separation of SCG and FLU on silica gel 60 F₂₅₄ using chloroform:methanol:toluene:triethylamine in the ratio of (5:2:4:1 v/v/v/v) as developing system, followed by spectrodensitometric measurement of the bands at 241 nm. The linearity ranges and the mean percentage recoveries/RSD were found to be (0.4–4.4 μg/band), 100.24/1.44 and (0.2–1.6 μg/band), 99.95/1.50 for SCG and FLU, respectively. A comparative study was conducted between the proposed methods to discuss the advantage of each method. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for the determination of SCG and FLU in their laboratory prepared mixtures and commercial ophthalmic solution in the presence of benzalkonium chloride as a preservative. These methods could be an alternative to different HPLC techniques in quality control laboratories lacking the required facilities for those expensive techniques.     

Time to Relief of Episodic Symptoms of Gastro-Oesophageal Reflux Disease: A Crossover Comparison of Single Doses of the Effervescent and Standard Formulations of Ranitidine

Background: The length of time until symptom relief and the consistency of response are important aspects of the management of episodes of gastro-oesophageal reflux disease (GORD). Methods: In an open, randomized, crossover study 98 patients treated 3 episodes of GORD with ranitidine effervescent formulation and 3 with ranitidine standard formulation. The patients filled in a diary card during the 1st h after each study medication. Satisfaction with the formulations and the formulation of choice were determined at the end of the study. Results: A higher percentage of episodes with acceptable symptom relief (82.4% versus 73.1%; P = 0.024) and a shorter time to acceptable symptom relief (27 min versus 36 min; P < 0.001) were achieved with the effervescent formulation. Sixty-five per cent preferred the effervescent formulation (P < 0.01). Conclusions: An increased consistency of response and a more rapid symptom relief were achieved with treatment with the ranitidine effervescent formulation, indicating it may be more appropriate for on-demand treatment in patients with episodes of GORD.     

Design and Characterisation of a Tissue Phantom System for Optical Diagnostics

We present an optical phantom system especially suited to investigating the generation and transport of laser-induced fluorescence in biological tissues. The phantom system consists of micrometre-sized particles of aluminium oxide, iron and coloured resin dispersed in a solid, transparent host (polyorganosiloxane), from which mechanically stable samples can be made. Mie theory is applied to predict the radiation transport parameters from the optical properties of the isolated components. The predictions are in good agreement with the results of integrating sphere measurements. The radiation transport parameters of the samples are reproducible and temporally stable. Received for publication 4 June 1997; accepted following revision 8 November 1997.     

Variability in absorption lag time of pyridoxal phosphate under fasting and pre- and post-meal conditions

Inter-individual variations in the absorption lag time of pyridoxal phosphate were determined after administration of an enteric-coated tablet (EC) or a plain capsule (PC) to 113 healthy volunteers under fasting, pre-meal, and post-meal conditions. The absorption lag time of pyridoxal phosphate was assessed from the urinary excretion of 4-pyridoxic acid after administration of EC and PC. Significantly larger lag times after administration of both formulations were observed under post-meal conditions than under pre-meal conditions (0.477 ± 0.315 h versus 0.081 ± 0.086 h for PC and 1.995 ± 1.345 h versus 1.064 ± 1.327 h for EC), indicating that the mean gastric emptying rates of both a solution and a tablet were delayed after food intake. The lag time for PC showed little inter-individual variation with (0–1.2 h) or without food (0–0. 25 h), whereas that for EC showed markedly large inter-individual variation, from 0.25 to 2.63 h (median, 1.5 h) in the fasting condition, from 0.25 to > 5.5 h (median 0.25 h) under pre-meal conditions, and from 0.25 to > 5.5 h (median 1.25 h) under post-meal conditions. The effect of food on the gastric emptying rate of a solution appears to be almost uniform, whereas that for a tablet is so unpredictable that a reliable absorption rate for an enteric-coated tablet cannot be expected, particularly under pre- and post-meal conditions.     

水稻耐盐机理的研究：Ⅱ,不同基因型愈伤组织耐盐性比较

氯化钠胁迫对水稻愈伤组织的生长有明显的影响。表现为存活率下降、生长量减少以及干/鲜值增加等。然而用上述指标进行比较,具有植株水平耐盐性差异的不同基因型,愈伤组织之间却没有显著差异,表明植株水平的耐盐程度与愈伤组织的耐盐程度之间没有直接联系。在氯化钠胁迫的情况下,耐盐基因型愈伤组织的K~+含量低于盐敏感基因型,而前者的Na~+和Cl~-含量却略高于后者。这种趋势与植株水平不一致,暗示了愈伤组织水平对无机离子的吸收可能具有与植株水平不同的机制。     

Simulated parametric studies in optical imaging of tumors through temporal log-slope difference mapping

Numerical studies are conducted to evaluate the noninvasive imaging method of temporal log-slope difference mapping (TLSDM). Emphasis is placed on the parametric examination of tumor's size, enhanced absorption contrast ratio, and embedment depth on the imaging quality and accuracy. It is found that the imaging quality and accuracy are predominantly determined by the tumor size and its embedment depth. The TLSDM method can detect a small tumor of 10 mm in size when the tumor is embedded at a shallow depth down to 10 mm. With decreasing tumor size and/or increasing embedment depth, both image quality and accuracy worsen. The imaging method requires the enhanced absorption contrast ratio be 20:1 or above.     

Lymphatic and portal venous transport of alpha-tocopherol and cholesterol

The absorption of ³H-α-tocopherol was studied in rats after intraduodenal administration in micellar solutions. Net absorption from mixed micelles in lymph fistula rats was 66%, but only 42% appeared in lymph and 3% was excreted in urine. Administration of ³H-α-tocopherol in taurocholate micelles reduced both the rate of absorption into lymph and the proportion carried in chylomicrons. In studies with lymph and bile duct cannulated rats, up to 8% of the radioactivity was excreted in bile, irrespective of whether the cannula was in the mesenteric or thoracic lymph duct. These findings suggested that radioactivity was being absorbed via the portal vein, which was confirmed by demonstrating a higher concentration in portal than in aortic plasma. Radioactivity in plasma partly consisted of polar metabolites, in contrast to lymph where over 90% was free α-tocopherol. In parallel experiments with ¹⁴C-cholesterol, significant amounts of radioactivity were excreted in bile and the ratio of portal: aortic radioactivity again suggested absorption via the portal route. The majority of ¹⁴C-cholesterol in portal plasma was free sterol, in contrast to lymph where it was mainly esterified. These results suggest that small amounts of both α-tocopherol and free cholesterol can be transported from the intestine via the portal vein, although under normal circumstances absorption of both compounds occurs mainly via the lymphatic pathway.     

地域、个人卫生及肠道功能对CAPD患者腹膜炎发生率的影响

目的探讨地域、个人卫生状况及肠道功能对持续性非卧床腹膜透析（CAPD）患者并发感染性腹膜炎的影响。方法选取2008～2014年在本院行腹膜透析置管术的CAPD患者133例,按腹膜炎诊断标准,分为腹膜炎组和非腹膜炎两组,记录CAPD患者一般资料（性别、年龄、居住地、文化程度、原发病等）,个人卫生,腹泻便秘等情况,分析这些因素与感染性腹膜炎之间的关系。结果两组患者长期居住地比较差异具有统计学意义（P＜0．05）,而两组患者性别、年龄、身高、体质量、体质量指数、文化程度、原发病、是否合并糖尿病相比较差异无统计学意义（ P ＞0．05）。对两组患者资料采用二分类 Logistic回归分析,结果表示地域（乡镇及农村）[OR＝5．876, P ＝0．000]、个人卫生中洗手[O R＝5．596, P ＝0．009]与刷牙[O R＝4．865, P ＝0．003]、腹泻[O R＝5．744,P ＝0．006]及便秘[OR＝2．332,P ＝0．016]是腹膜炎发生的影响因素。结论地域、个人卫生、腹泻便秘是腹膜炎发生的影响因素,在临床工作中应加强乡镇及农村患者对腹膜炎的预防意识,重视对腹膜透析患者的卫生教育,以减少腹膜透析相关性腹膜炎的发生。