Twelve-hour shift on ITU: a nursing evaluation

This paper describes the introduction and subsequent evaluation of a 12-h shift system in a large ITU in the northeast of UK. To date, only a small number of studies has evaluated nurses working the 12-h shifts in critical care areas. To evaluate the level of staff satisfaction, data were collected by means of a questionnaire involving 41 nurses, at 3 months following the introduction of the 12-h shifts. The responses from the evaluation advocated the continuation of 12-h shifts with alternative shift patterns for nurses who felt dissatisfied with the current system. Twelve-hour shifts can be seen as a flexible system for nurses working in intensive care and may assist with staff satisfaction and improving nurse recruitment and retention.     

The Rate and Extent of Oral Bioavailability versus the Rate and Extent of Oral Absorption: Clarification and Recommendation of Terminology

In the literature, the meanings of the terms oral absorption and oral bioavailability of drugs vary greatly. Absorption has been considered to take place at the mucosal membrane of the gastrointestinal (GI) tract. It has also been defined as the process from the site of drug administration to the site of measurement. In the latter definition, the extent of oral absorption depends on the extent of first-pass elimination in the gut wall and liver even though a drug may be completely absorbed from the GI tract. Moreover, these two terms have also been used interchangeably. Inconsistency in the definition of these two terms has led to varying interpretations of these terms among students, researchers and laymen, and such an inconsistency seems undesirable. Apparently because of these inconsistencies, improper correlations between the Caco-2 permeability or intestinal permeability and the oral bioavailability of drugs subject to extensive first-pass effect may have occurred. It is suggested that absorption be defined as movement of drug across the outer mucosal membranes of the GI tract, while bioavailability be defined as availability of drug to the general circulation or site of pharmacological actions. Since transit times (this may range from about 1 min to several hours) across enterocytes, liver, lungs, and the peripheral venous sampling tissue are virtually unknown for all drugs, this factor alone would favor the use of oral bioavailability rate rather than oral absorption rate in all routine studies.     

A Physiologically Based Pharmacokinetic Analysis of Capecitabine,a Triple Prodrug of 5-FU,in Humans: The Mechanism for Tumor-Selective Accumulation of 5-FU

Purpose. To identify the factors governing the dose-limiting toxicity in the gastrointestine (GI) and the antitumor activity after oral administration of capecitabine, a triple prodrug of 5-FU, in humans. Method. The enzyme kinetic parameters for each of the four enzymes involved in the activation of capecitabine to 5-FU and its elimination were measured experimentally in vitro to construct a physiologically based pharmacokinetic model. Sensitivity analysis for each parameter was performed to identify the parameters affecting tissue 5-FU concentrations. Results. The sensitivity analysis demonstrated that (i) the dihydropyrimidine dehydrogenase (DPD) activity in the liver largely determines the 5-FU AUC in the systemic circulation, (ii) the exposure of tumor tissue to 5-FU depends mainly on the activity of both thymidine phosphorylase (dThdPase) and DPD in the tumor tissues, as well as the blood flow rate in tumor tissues with saturation of DPD activity resulting in 5-FU accumulation, and (iii) the metabolic enzyme activity in the GI and the DPD activity in liver are the major determinants influencing exposure to 5-FU in the GI. The therapeutic index of capecitabine was found to be at least 17 times greater than that of other 5-FU-related anticancer agents, including doxifluridine, the prodrug of 5-FU, and 5-FU over their respective clinical dose ranges. Conclusions. It was revealed that the most important factors that determine the selective production of 5-FU in tumor tissue after capecitabine administration are tumor-specific activation by dThdPase, the nonlinear elimination of 5-FU by DPD in tumor tissue, and the blood flow rate in tumors.     

Racial variation in fasting and random homocysteine levels

Homocysteine (Hcy) levels have been shown to be a predeterminant of thrombotic diseases. We measured the Hcy levels of 50 blacks and 50 whites equally divided by gender to determine if there is a significant racial difference in either fasting or random Hcy levels. Dietary, medication, smoking, alcohol, past medical, educational, and occupational histories were obtained, and the body mass index calculated. Total serum fasting and random Hcy levels, B12, folate, BUN, creatinine, and lipid profiles were drawn from each participant. Analysis of the results showed that white males have the highest fasting Hcy levels, 10.5 microM/l, whereas random Hcy levels were not significantly different. Correlation between fasting and random Hcy levels was poor (R = 0.61). B12 levels in black subjects were significantly higher, 490.8 pg/ml, compared to whites, 382.8 pg/ml, P = 0.001, but contributed little to total Hcy levels (R(2) = 0.08). Folic acid levels, all within normal range, were not significantly different between the two racial groups and also did not appear to greatly affect Hcy levels (R(2) = 0.06). Our study demonstrates that, despite the genetic diversity of these two racial groups in the U.S., white males in this age group have higher fasting Hcy levels than black males, and white males, but not black males, have higher fasting homocysteine levels than females. This discrepancy in Hcy levels may reflect methylene-tetrahydrofolate reductase (MTHFR) enzyme polymorphisms, known to be higher in whites, rather than socioeconomic influences.     

Fine mapping and genetic heterogeneity in the pure form of autosomal dominant familial spastic paraplegia

We evaluated seven families segregating pure, autosomal dominant familial spastic paraplegia (SPG) for linkage to four recently identified SPG loci on chromosomes 2q (1), 8q (2), 12q (3), and 19q (4). These families were previously shown to be unlinked to SPG loci on chromosomes 2p, 14q, and 15q. Two families demonstrated linkage to the new loci. One family (family 3) showed significant evidence for linkage to chromosome 12q, peaking at D12S1691 (maximum lod=3.22). Haplotype analysis of family 3 did not identify any recombinants among affected individuals in the 12q candidate region. Family 5 yielded a peak lod score of 2.02 at marker D19S868 and excluded linkage to other known SPG loci. Haplotype analysis of family 5 revealed several crossovers in affected individuals, thereby potentially narrowing the SPG12 candidate region to a 5-cM region between markers D19S868 and D19S220. Three of the families definitively excluded all four loci examined, providing evidence for further genetic heterogeneity of pure, autosomal dominant SPG. In conclusion, these data confirm the presence of SPG10 (chromosome 12), potentially reduce the minimum candidate region for SPG12 (chromosome 19q), and suggest there is at least one additional autosomal dominant SPG locus. Electronic Publication     

支气管哮喘患者白细胞介素12、免疫球蛋白E及内皮素1的水平测定及意义

支气管哮喘是临床常见的呼吸道疾病，是呼吸道慢性变态反应性炎症性疾病。气道慢性变态反应性由多种炎性细胞、炎性介质和细胞因子共同参与，检测哮喘患者自细胞介素（interleukin，IL）-12、免疫球蛋白E（immunoglobulin—E，Ig—E）及内皮素1（endothelin-1，ET-1）水平，以探讨三者在支气管哮喘不同病程中的作用。     

关于正确处理公立医院积累与分配关系的几点思考

公立医院持续健康发展的重要一环就是科学把握积累与分配的关系。公立医院需要通过积累扩大再生产,但同样需要按生产要素进行合理分配。积累与分配比例应为业务收支结余(不含人员经费和修购基金)的4∶6,潍坊市的做法为这一"黄金分割"提供了实证。     

胰岛素、地塞米松和米非司酮对PC12细胞合成和分泌儿茶酚胺的影响及机制探究

目的：考察胰岛素、地塞米松及米非司酮对PC12细胞合成和分泌儿茶酚胺的影响。方法：常规培养及用100 nmol/L的胰岛素（造成胰岛素抵抗模型）培养PC12细胞24小时,单用及合用胰岛素、地塞米松和米非司酮作用于PC12细胞24小时,用荧光检测法检测缓冲液及裂解液中儿茶酚胺的含量。结果：在正常组和模型组中,高浓度的胰岛素（≥100 nmol/L）和地塞米松（≥3μmol/L）单用时,PC12细胞的儿茶酚胺合成和分泌均显著增加（P〈0.01）,而米非司酮单用对PC12细胞的儿茶酚胺合成和分泌无显著影响;胰岛素与地塞米松合用时,随地塞米松浓度的增加,PC12细胞的儿茶酚胺的分泌增加,且当地塞米松浓度高于3μmol/L时,PC12细胞的儿茶酚胺分泌量与不加用地塞米松相比有显著性差异（P〈0.01）;胰岛素、地塞米松和米非司酮合用时,随米非司酮浓度的增加,PC12细胞的儿茶酚胺分泌逐渐减少。在模型组中,胰岛素、地塞米松和米非司酮单用及合用对胞内儿茶酚胺含量均无明显影响。结论：胰岛素和糖皮质激素可显著增加儿茶酚胺的合成和分泌,米非司酮则能抑制这种增强效应。     

Mechanism of apoptosis induced by copper in PC12 cells

Copper, an essential trace element, induces apoptosis in mammalian cells. However, the precise mechanism of copper-induced apoptosis is still unclear. In this study, to determine the apoptotic pathway initiated by copper treatment, apoptotic factors such as Bax, Bad and Bcl-2, and the caspase family in PC12 cells treated with copper were measured by Western blot and RT-PCR analyses. The expression of Bax, Bad, cytochrome c and caspases 3 and 9 were increased by copper treatment. From these results, two pathways for copper-induced apoptosis were suggested. At first, an increase of Bax induces the release of cytochrome c from the mitochondria into the cytoplasm owing to binding to apoptotic activating caspase 9 leading to the activation of caspases 3. In the other pathway an increase of Bax and reactive oxygen species activates the release of AIF from the mitochondria. The AIF induces apoptosis via a caspase-independent pathway.