Intracellular [Na+], Na+ pathways, and fluid transport in cultured bovine corneal endothelial cells

The mechanism of fluid transport across corneal endothelium remains unclear. We examine here the relative contributions of cellular mechanisms of Na+ transport and the homeostasis of intracellular [Na+] in cultured bovine corneal endothelial cells, and the influence of ambient Na+ and HCO3- on the deturgescence of rabbit cornea. Bovine corneal endothelial cells plated on glass coverslips were incubated for 60 min with 10 microm of the fluorescent Na+ indicator SBFI precursor in HCO3- HEPES (BH) Ringer's solution. After loading, cells were placed in a perfusion chamber. Indicator fluorescence (490 nm) was determined with a Chance-Legallais time-sharing fluorometer. Its voltage output was the ratio of the emissions excited at 340 and 380 nm. For calibration, cells were treated with gramicidin D. For fluid transport measurements, rabbit corneas were mounted in a Dikstein-Maurice chamber, and stromal thickness was measured with a specular microscope. The steady-state [Na+]i in BH was 14.36+/-0.38 mM (n = mean+/-s.e.). Upon exposure to Na+ -free BH solution (choline substituted), [Na+]i decreased to 1.81+/-0.20mM (n = 19). When going from Na+ -free plus 100 microm ouabain to BH plus ouabain, [Na+]i increased to 46.17+/-2.50 (n = 6) with a half time of 1.26+/-0.04 min; if 0.1 microm phenamil plus ouabain were present, it reached only 21.78+/-1.50mm. The exponential time constants (min-1) were: 0.56+/-0.04 for the Na+ pump; 0.39+/-0.01 for the phenamil sensitive Na+ channel; and 0.17+/-0.02 for the ouabain-phenamil-insensitive pathways. In HCO3- free medium (gluconate substituted), [Na+]i was 14.03+/-0.11mM; upon changing to BH medium, it increased to 30.77+/-0.74 mm. This last [Na+]i increase was inhibited 66% by 100 microm DIDS. Using BH medium, corneal thickness remained nearly constant, increasing at a rate of only 2.9+/-0.9 microm hr-1 during 3 hr. However, stromal thickness increased drastically (swelling rate 36.1+/-2.6 microm hr-1) in corneas superfused with BH plus 100 microm ouabain. Na+ -free, HCO3- free solution and 100 microm DIDS also led to increased corneal swelling rates (17.7+/-3.6, 14.4+/-1.6 and 14.9+/-1.2 microm hr-1, respectively). The present results are explained by the presence of a DIDS-inhibitable Na+-HCO3- cotransporter and an epithelial Na+ channel, both previously found in these cells. On the other hand, the quantitative picture presented here appears a novelty. The changes we observe are consistent with pump-driven rapid exchange of intracellular Na+, and recirculation of fully 70% of the Na+ pump flux via apical Na+ channels.     

The measurement of liver blood flow: a review of experimental and clinical methods

Changes in hepatic blood flow reflect adaptive responses of the liver to injury, regeneration, and the development of disease states. The measurement of hepatic blood flow is, however, technically challenging and although theoretically useful has not become routine in clinical work. The different techniques that have been developed for quantitative measurement of hepatic blood flow require careful interpretation of the results obtained but are frequently applied without careful considerations of their technical limitations. In particular, many noninvasive techniques depend on good hepatocellular function and are thus irrelevant under most clinical conditions. Many other potentially useful techniques are poorly validated and standardized and there is a need for further research into smethodology. This review summarizes the salient technical features of the different techniques for quantitative measurement of hepatic blood flow. The techniques are divided into invasive, minimally invasive, and noninvasive categories and the relevance of each technique to both routine clinical application or research is discussed.     

Common loon eggs as indicators of methylmercury availability in North America

Increased anthropogenic mercury (Hg) deposition since pre-industrial times, and subsequent transformation of inorganic Hg to methylmercury (MeHg) in aquatic environments, has created areas in North America where Hg poses a relatively high risk to wildlife, especially long-lived, piscivorous species. From 1995 to 2001, we opportunistically collected 577 eggs abandoned by Common Loons from eight states. Egg-Hg concentrations ranged from 0.07 to 4.42 µg/g (ww) or 0.10 to 19.40 µg/g (dw). Mercury was higher in eastern than in western North America. Female blood-Hg concentrations strongly correlated with those of eggs from the same territory even though the mean intraclutch Hg difference was 25%. In New England, egg volume declined significantly as egg-Hg concentrations increased. Fertility was not related to egg-Hg concentrations. Based on existing literature and this study's findings, egg-Hg risk levels were established and applied to our US data set and an existing Canadian data set. Regionally, we found the greatest risk levels in northeastern North America. With few exceptions, loon eggs are suitable indicators of methylmercury availability on lakes with territorial pairs.     

The validity of self-reported leisure time physical activity,and its relationship to serum cholesterol,blood pressure and body mass index. A population based study of 332,182 men and women aged 40-42 years

The importance of leisure time physical activity as a health indicator became more obvious after the results of large prospective studies were published. The validity of these results depends upon both the selection of the active individuals and to what extent self-reported physical activity reflects the individual's true activity. The purpose of this paper is to describe the changes in self-reported physical activity, and to assess the relation between this variable and other biological risk factors such as blood lipids, blood pressure and body mass index (BMI). This report also aims at corroborating the validity of self-reported physical activity by assessing the consistency of the associations between these biological risk factors and physical activity during a 25-years period. The basis for this analysis is a long lasting observational study with a questionnaire as the most important research instrument, in addition to physiological and biological factors such as BMI, blood pressure and blood lipids. The study population consists of 332,182 individuals, aged 40–42 from different counties in Norway who were invited to participate in health survey during 1974–1999. The objectives of this study are (1) to describe changes in self-reported physical activity from 1974 to 1999; (2) to assess the relation between physical activity and the biological variables; and (3) to corroborate the validity of the variable physical activity by assessing the consistency of the above analysis. The results of the analyses of association between decade of birth and self-reported physical activity show that physical activity among 40-aged individuals decreased during 1974–1999. This trend is stronger among the men. Multivariate analyses revealed differences in BMI and serum cholesterol between levels of self-reported physical activity, gender, smoking habits and decade of birth. The explained percentage of the total variance ranged from 6% for BMI to 7% for serum cholesterol. The similar shape of serum cholesterol and BMI according to physical activity indicates that the validity of self-reported physical activity has remained stable over these 25 years. Furthermore, the analysis of covariance showed that the slopes relating year of birth and serum cholesterol and BMI are parallel for self-reported physical activity thus the validity of the variable is confirmed.     

Prognostic importance of survivin in breast cancer

Survivin is a member of the inhibitor of apoptosis (IAP) family, and is also involved in the regulation of cell division. Survivin is widely expressed in foetal tissues and in human cancers, but generally not in normal adult tissue. This study examined the expression of surviving protein in a series of 293 cases of invasive primary breast carcinoma. Survivin immunoreactivity was assessed using two different polyclonal antibodies, and evaluated semiquantitatively according to the percentage of cells demonstrating distinct nuclear and/or diffuse cytoplasmic staining. Overall, 60% of tumours were positive for survivin: 31% demonstrated nuclear staining only, 13% cytoplasmic only, and 16% of tumour cells demonstrated both nuclear and cytoplasmic staining. Statistical analysis revealed that survivin expression was independent of patient's age, tumour size, histological grade, nodal status, and oestrogen receptor status. In multivariate analysis, nuclear survivin expression was a significant independent prognostic indicator of favourable outcome both in relapse-free and overall survival (P<0.001 and P=0.01, respectively). In conclusion, our results show that survivin is frequently overexpressed in primary breast cancer. Nuclear expression is most common and is an independent prognostic indicator of good prognosis.     

新型农村合作医疗常规评价指标体系的研究

采用专家咨询法、离散趋势法和指标聚类法等3种方法,并采用单选和联合筛选的办法,从34项初选指标中选出了比较符合实际的13项指标,并采用等效性检验验证了13项指标的代表性,组成评价体系。建议在实际工作中模拟试用这13项指标,并根据具体情况再行调整。     

血清生化指标对胆源性胰腺炎的诊断意义

目的探讨血清生化指标的改变对诊断胆源性胰腺炎的临床意义。方法将107例急性胰腺炎患者分为胆源性及非胆源性胰腺炎两组,并对其血清生化指标TBIL、DBIL、ALT、AST、ALP、r-GT的改变进行回顾性分析。结果胆源性胰腺炎组生化指标异常升高的改变显著高于非胆源性胰腺炎组（P〈0.01）。结论血清TBIL、DBIL、ALT、AST、ALP、r-GT的异常升高对急性胆源性胰腺炎诊断有重要的参考意义。     

茯苓甘草复方合剂对铝染毒小鼠生化指标影响的实验研究

目的研究茯苓甘草复方合剂对铝染毒小鼠生化指标的影响。方法用氯化铝水溶液给小白鼠灌胃3个月,复制染毒模型,然后分为治疗组、染毒组(染毒不治疗组),另设正常组(不染毒,作正常对照)。治疗组用茯苓甘草复方合剂灌胃治疗。实验结束,取血清、大脑组织测定生化指标。结果正常组、治疗组、染毒组乙酰胆碱酯酶(AchE)活力分别是:(0.74±0.18)I U/mg、(0.88±0.13)I U/mg、(1.36±0.18)I U/mg,染毒组明显高于其余2组(P<0.01);实验前、后测Hb结果分别是:(158.42±11.84)g/L、(163.40±7.85)g/L、(161.80±10.02)g/L、(144.16±5.44)g/L、(142.77±23.50)g/L、(128.81±15.90)g/L,染毒组实验结束明显降低(P<0.01);尿素氮(BUN)分别是(7.14±1.51)mmol/L、(8.62±3.53)mmol/L、(10.47±3.29)mmol/L,染毒组明显高于正常组(P<0.05)。结论铝染毒小鼠大脑AchE活力和BUN明显升高,Hb明显降低,而治疗组有明显恢复。     

Cellular Pharmacokinetics: Effects of Cytoplasmic Diffusion and Binding on Organ Transit Time Distribution

Distribution between well-stirred compartments is the classical paradigm in pharmacokinetics. Also in capillary–issue exchange modeling a barrier-limited approach is mostly adopted. As a consequence of tissue binding, however, drug distribution cannot be regarded as instantaneous even at the cellular level and the distribution process consists of at least two components: transmembrane exchange and cytoplasmic transport. Two concepts have been proposed for the cytoplasmic distribution process of hydrophobic or amphipathic molecules, (i) slowing of diffusion due to instantaneous binding to immobile cellular structures and (ii) slow binding after instantaneous distribution throughout the cytosol. The purpose of this study was to develop a general approach for comparing both models using a stochastic model of intra- and extravascular drug distribution. Criteria for model discrimination are developed using the first three central moments (mean, variance, and skewness) of the cellular residence time and organ transit time distribution, respectively. After matching the models for the relative dispersion the remaining differences in relative skewness are predicted, discussing the relative roles of membrane permeability, cellular binding and cytoplasmic transport. It is shown under which conditions the models are indistinguishable on the basis of venous organ outflow concentration–time curves. The relative dispersion of cellular residence times is introduced as a model-independent measure of cytoplasmic equilibration kinetics, which indicates whether diffusion through the cytoplasm is rate limiting. If differences in outflow curve shapes (their relative skewness) cannot be detected, independent information on binding and/or diffusion kinetics is necessary to avoid model misspecification. The method is applied to previously published hepatic outflow data of enalaprilat, triiodothyronine, and diclofenac. It provides a general framework for the modeling of cellular pharmacokinetics.     

全血质控物开启后温度和时间对测定结果的影响

[目的 ]观察全血质控物开启后温度和时间对测定结果的影响 .[方法 ]用全自动血球计数仪K 4 50 0检测 ,对结果进行了t检验 .[结果 ]全血质控物开启后于 4℃冰箱 4 8h与原定值比较 ,差异无显著性 .室温 2 5℃ 12h以上时差异有显著性 .[结论 ]常规工作中打开启用全血质控物后 ,放置室温 6h内时可以重复使用 ,但最好加盖置于 4℃冰箱内 .