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81.
Studying the effects of microgravity on cell differentiation will enhance our understanding of fundamental biology and is indispensable for a sustained space program. Rauscher murine erythroleukemic cells were chosen as a model system to study erythroid cell differentiation aboard the International Space Station because these cells undergo differentiation in response to the natural inducer, erythropoietin, as well as various chemical inducers. We have now developed a method to quantify hemoglobin in Rauscher cells after weeks of fixation and storage required for such space biology experiments. By exploiting the pseudoperoxidase activity of hemoglobin and by using reagents that yield a soluble chromophore that freely passes out of fixed cells, we developed a highly specific and sensitive assay applicable to cells fixed as long as 4 months. 相似文献
82.
大气细菌粒子浓度的时间分布特征及最佳采样时间的研究 总被引:4,自引:0,他引:4
用MF-45型和HTK-201型空气微生物采样器分别在北京、天津和沈阳三地观测了不同季节和一天中大气细菌粒子的浓度及其变化。结果表明:京、津二地春季大气细菌粒子浓度高,分别为2053个/m3和2556个/m3;夏季低,分别为995个/m3和1064个/m3。沈阳秋季大气细菌粒子浓度高,为10108个/m3;冬季低,为1294个/m3。一天中,大气细菌粒子浓度呈双峰型变化,6:00~7:00和18:00时大气细菌粒子浓度高,11:00~13:00和1:00~2:00时大气细菌粒子浓度低。根据大气细菌粒子浓度的季节变化和一天中大气细菌粒子浓度的时间分布特征,经过京、津、沈三地一天中分别12次、8次、6次和4次不同采样时间组合的大气细菌粒子浓度的数理统计分析,大气细菌粒子浓度的监测拟集中在一年冬、春、夏、秋四季的中间月份,即1月、4月、7月、10月进行;一天中采样8次的时间序列可为7:00、10:00、13:00、16:00、19:00、22:00、1:00、4:00一天采样4次的时间序列可为5:00、11:00、17:00、23:00。白天采样4次的时间序列可为春、秋季6:00、9:00、12:00、15:00? 相似文献
83.
84.
Ant nio F. Ambr sio Jo o O. Malva Ars lio P. Carvalho Caetana M. Carvalho 《European journal of pharmacology》1997,340(2-3):301-310
The effects of the adenosine A1 receptor agonist, N6-cyclopentyladenosine (CPA), on both the increase in intracellular free Ca2+ concentration ([Ca2+]i) and on the release of endogenous glutamate in rat hippocampal synaptosomes were studied. The inhibitory effect of CPA on the increase in [Ca2+]i stimulated with 4-aminopyridine was neutralized by the adenosine A1 receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). The inhibitory effect of CPA was greater in synaptosomes from the CA1 subregion than in whole hippocampal synaptosomes. The inhibitory effects of both CPA and of the Ca2+ channel blockers, ω-conotoxin GVIA, ω-conotoxin MVIIC or ω-conotoxin GVIA plus ω-conotoxin MVIIC, were greater than those caused by the Ca2+ channel blockers. The release of endogenous glutamate was inhibited by 41% by CPA. The inhibition observed when CPA and ω-conotoxin GVIA or CPA and ω-conotoxin MVIIC were present was also greater than the inhibition by the Ca2+ channel blockers alone. The presence of both ω-conotoxin GVIA and ω-conotoxin MVIIC did not completely inhibit the release of glutamate, and CPA significantly enhanced this inhibition. The membrane potential and the accumulation of []tetraphenylphosphonium of polarized or depolarized synaptosomes was not affected by CPA, suggesting that adenosine did not increase potassium conductances. The present results suggest that, in hippocampal glutamatergic nerve terminals, adenosine A1 receptor activation partly inhibits P/Q- and other non-identified types of Ca2+ channels. 相似文献
85.
反相高效液相色谱法测定血浆中氢溴酸右美沙芬浓度 总被引:8,自引:1,他引:7
本文报道采用反相高效液相色谱法测定人血浆中氢溴酸右美沙芬的浓度。采用YWG-C18H37分析柱,以乙腈-水-乙酸(50:49:1,三乙胺调节pH至4.3)为流动相,利多卡因作内标,在278nm波长处监测洗提液。本法简便,灵敏,专属性好,适用于氢溴酸右美沙芬血药浓度测定及药代动力学研究 。 相似文献
86.
Background Prosia gland in D2 (PGD2) is a very important mast cell product during the early-phase nasal allergic reaction. However, the quantification of PGD2 in nasal secretions has not yet been well established. Objective Quantitative determination of PGD2 in nasal secretions of atopic patients (n=17) after nasal allergen challenge (NAC) and in non-allergic healthy volunteers (n=10). Methods The nasal microsuction sampling technique was used to obtain the nasal secretions with an exactly known and minimally diluted volume. A sensitive and specific enzyme immunoassay was chosen to measure the more stable 11-methoxime derivative of PGD2. which was obtained after extraction in acelone/ethanol and conversion using methoxamine-HCl. The concentrations of PGD2 in nasal secretions obtained from 10 non-allergic healthy volunteers were used as reference values. Results There was no significant difference in the concentrations of PGD2 between men (median: 569pg/mL) and women (median: 407pg/mL), nor between the baseline concentrations from atopic patients (median: 410pg/mL) and non-allergic controls (median: 477 pg/mL). In the atopic patient group, PGD2 did not significantly increase during the entire sampling period after NAC. The absence of PGD2 response contrasted with the nasal symptoms manifested by sneezing, increased nasal airway resistance, and the significant increases of the concentrations of histamine, tryptase, and leukotriene C4 (LTC4) 5min after NAC. Conclusion This observation suggests that the measurement of PGD2 alone in the nasal secretions does not give reliable information on mast cell activation during a nasal allergic reaction. 相似文献
87.
A microcapsule form of nitrofurantoin was prepared by a simple coacervation method with carboxymethylcellulose and aluminium sulfate. 33 factorial design was performed for three independent variables, namely, the particle size of the drug, the size of the microcapsules and the pH of the dissolution medium. The dissolution tests with the formulated microcapsules were carried out according to the United States Pharmacopeia XXII rotating basket method at pH 1.2, 5 and 7.5, which represent the pH of gastrointestinal fluids. Release data were examined kinetically and the ideal kinetic models were estimated and t
63.2 values obtained from RRSBW distribution were used in the factorial design experiment. The influence of the independent variables on the dissolution of nitrofurantoin microcapsules could be expressed as the pH of the dissolution medium > particle size of the microcapsule > particle size of nitrofurantoin. The other aim of this study was to evaluate microcapsule formulation in terms of the United States Pharmacopeia criteria with a minimum of experiments. Our findings suggest that dosage forms which comply with the pharmacopoeia criteria for dissolution can be prepared and selected by factorial design. 相似文献
88.
Eight adult cats of either sex were studied. The minimal alveolar concentration (MAC) for sevoflurane in the cats was found to be 2.58 ± 0.30% (mean ± SD). The ratios of MAC values between sevoflurane and halothane, enflurane and isoflurane in cats were very similar to those ratios found in humans and dogs. This observation suggests that the results of this study are correct and allows us to estimate unknown MAC values for sevoflurane in other species using known MAC values for other anesthetic agents.(Doi M, Yunoki H, Ikeda K: The minimum alveolar concentration of sevoflurane in cats. J Anesth 2: 113–114, 1988) 相似文献
89.
Robert H. Smallwood George W. Mihaly Richard A. Smallwood Denis J. Morgan 《Journal of pharmacokinetics and pharmacodynamics》1988,16(5):529-542
For substances eliminated from blood by the liver, the effect of a change in unbound fraction of drug (fu
b
)on steady state total (C
b
)and unbound (Cu
b
)blood concentrations has hitherto only been considered for the two limiting cases, i.e., at the upper and lower extremes of hepatic intrinsic clearance (CL
int
).For a substance of very low CL
int
,if fu
b
changes, C
t
will change and Cu
b
will remain constant, whereas if CL
int
isvery high, Cu
b
will change and C
b
will remain constant.The present study defines the effects of a change in fu
b
on C
b
and Cu
b
over the whole CL
int
range. Computer simulations were undertaken which predicted that, for a given change in fu
b
,absolute and relative changes in C
b
would decreasenonlinearly with increasing CL
int, twhile the relative change in Cu
b would increasewith CL
int
.The absolute change in Cub
would be independent of CL
int
.Significant changes in Cb and Cu
b would be observed at intermediate values of CL
int not just at the high and low extremes. These theoretical predictions were investigated experimentally in the isolated perfused rat liver by examining the effects of a change in fu
b of sodium taurocholate a substance with intermediate CL
int
(such that at fu
b
=0.27,hepatic extraction ratio=0.71) induced by concurrent administration of sodium oleate. Sodium 24-
14
C-taurocholate (specific activity 52 Ci/mmol) was infused into the reservoir in a recycling system at 30 mol/hr for 105 min (n=6). At 45 min a bolus dose of sodium oleate (50 mmol) was administered to the reservoir, followed by a constant infusion of 143 mmol/hr for 1 hr. Following the administration of oleate, taurocholate fu
b fell promptly by 55% (0.27–0.12). There was a relative increase of taurocholate C
b of 22.7% and a relative decrease in Cu
b of 45.4%, in accordance with the simulations (p<0.05). We conclude that important changes in unbound steady-state concentration, the pharmacologically active moiety, can occur upon changes in unbound fraction with compounds of intermediate hepatic intrinsic clearance.This study was supported by the National Health and Medical Research Council of Australia. 相似文献
90.
背景 目标范围内时间(TIR)作为血糖管理的新指标,与短期血糖波动相关,是否与长期血糖变异性相关尚不清楚。目的 探讨老年男性2型糖尿病患者TIR与长期随访期间糖化血红蛋白(HbA1c)变异系数、HbA1c变异性评分(HVS)的关系。方法 选取2007年1月至2011年1月在解放军总医院第二医学中心住院行动态血糖监测(CGM)的老年男性2型糖尿病患者200例,根据患者基线TIR水平,将其分为TIR≥85%组(n=141)和TIR<85%组(n=59)。对受试者随访观察(12.5±1.1)年,比较两组长期随访期间HbA1c变异系数和HVS。采用Pearson相关、多元线性回归分析TIR与HbA1c变异系数、HVS的关系。结果 TIR<85%组患者的长期HbA1c变异系数[(9.7±3.8)%比(8.2±4.5)%,P=0.028)]、HVS[(48.7±20.4)分比(32.5±20.8)分,P<0.001)]均明显高于TIR≥85%组。Pearson相关分析结果... 相似文献