Analysis using fluorescence polarization immunoassay for unbound teicoplanin concentration in serum

Objectives:  The aim of this study was to develop a simpler and more rapid analytical method for unbound teicoplanin in serum.
Methods:  A new analytical method was developed by modifying an existing fluorescence polarization immunoassay (FPIA) method. The validation of the developed FPIA method was compared in the quantification of unbound teicoplanin with that of the high-performance liquid chromatography (HPLC) method reported previously. The developed FPIA method was employed for the measurement of 36 clinical samples collected from patients with methicillin-resistant Staphylococcus aureus (MRSA) infection.
Results:  The limits of detection and quantification were 0·5 and 0·8 μg/mL, respectively. The recovery rate was 97·5–106·6%. The developed FPIA method showed better accuracy than the HPLC method. The within-run and interday reproducibility of the assay was good, with relative standard deviation values of 4·76–18·75% (within-run) and 5·68–13·95% (interday). Precision and accuracy of this method were within the acceptable limits defined in the US FDA Guidance for bioanalytical method validation. The correlation between the developed FPIA method and the HPLC method was good ( r ² = 0·87). A positive bias with the FPIA method was observed from the result of the Bland–Altman difference plot.
Conclusion:  We firmly believe that the present method is useful for the adjustment of teicoplanin dosages for patients under various conditions.     

Mechanized determination of the apparent unbound unconjugated bilirubin concentration in serum.

The peroxidase method for determining the apparent unbound bilirubin concentration in serum has been automated by use of a programmable, computer-directed spectrophotometer. This mechanized assay determines the total bilirubin concentration and apparent unbound bilirubin concentration in serum samples and titrates the serum with bilirubin to estimate the effect of increasing total bilirubin concentrations on the apparent unbound bilirubin concentration. The entire analysis requires 0.1 mL of serum and 4 min operation time, as compared with about 30 min for the manual method. The coefficients of variation for determination of the apparent unbound bilirubin concentration in bilirubin-enriched commercial control serum were 2.8% within-day and 5.6% between-day. Bilirubin--albumin binding in serum samples from infants with severe hyperbilirubinemia was analyzed by the manual peroxidase method, the automated peroxidase method, and Sephadex gel filtration. Good correlation was found among all three methods.     

Effect-site concentration of remifentanil for nasotracheal versus orotracheal intubation during target-controlled infusion of propofol

The concentration of remifentanil required for acceptable nasotracheal intubation in adults after target-controlled infusion (TCI) of propofol without neuromuscular blockade was compared with that required for orotracheal intubation. Twenty-five patients undergoing oral and maxillofacial surgery received nasotracheal intubation and 25 undergoing ear, nose and throat surgery received orotracheal intubation. Anaesthesia was induced with propofol TCI at a target effect-site concentration of 5.0 μg/ml. The 50% and 95% effective concentrations (EC(50) and EC(95), respectively) for remifentanil, calculated using isotonic regression, were 5.40 and 6.85 ng/ml, respectively, in the orotracheal group and 5.75 and 7.43 ng/ml in the nasotracheal group. The EC(50) (± SD) values for remifentanil, calculated using a modified Dixon's up-and-down method, were 6.08 ± 0.75 and 5.58 ± 0.75 ng/ml for nasotracheal and orotracheal intubation, respectively. Effect-site remifentanil concentrations did not differ significantly between the two groups of patients. Coadministration of propofol and remifentanil can provide acceptable conditions for nasotracheal intubation without neuromuscular blockade.     

Changes in intraocular pressure during surgery in the lateral decubitus position under sevoflurane and propofol anesthesia

Intraocular pressure (IOP) has been shown to change with body position. Several studies have shown that the lateral decubitus position (LDP) is associated with a significant increase in IOP in the dependent eye. However, whether anesthetic agents alter IOP in the LDP remains unclear. This study investigated the effect of sevoflurane and propofol anesthesia on IOP in the LDP. A total of 28 patients undergoing surgery in the LDP were included. Patients were randomly allocated to sevoflurane or propofol groups. IOP in both eyes was recorded and compared between groups at five time points: after anesthesia induction, after endotracheal intubation, at 5 min and 1 h after a positional change to the LDP, and 5 min after returning to the supine position. In the sevoflurane group, IOP was significantly increased in both dependent and non-dependent eyes 1 h after changing to the LDP. In the propofol group, IOP decreased in both dependent and non-dependent eyes after tracheal intubation, but did not increase after changing to the LDP. The number of patients in whom IOP increased to ≥28 mmHg was greater in the sevoflurane group than in the propofol group. Propofol may be better than sevoflurane for the maintenance of anesthesia in the LDP. Monitoring of IOP in the LDP might help avoid ophthalmic complications.     

Changes in red blood cell membrane phosphate concentration during blood bank storage

The change in red blood cell membrane phosphate concentration of standard CPD whole blood stored in Fenwal blood bags at 4 C was measured daily for two weeks. Membrane phosphate concentrations increased rapidly when stored pH fell to 6.95. At the same time, the rate of K+ leakage from the cells increased, and transport of inorganic phosphate across the membrane decreased. It is concluded that gross uptake of phosphorus by the red blood cell membrane during blood bank storage may be in part responsible for physical changes in the membrane.     

浅麻醉下犬脑组织对异丙酚的摄取及分布

目的 研究异丙酚浅麻醉时犬脑不同区域对药物的的摄取及分布情况，阐明异丙酚可能的中枢神经作用机制。方法 6条雄犬，在给予异丙酚静脉注射后，达到适当的麻醉深度后3min，取颈动脉和颈内静脉血并断头法将犬处死，解剖犬脑，分别在额叶、顶叶、颞叶、海马、扣带回、丘脑、中脑、桥脑、小脑等部位取标本。高效液相色谱－紫外线法测定血浆浓度及组织浓度。 结果 各个脑区药物浓度分布呈 桥脑＞中脑＞丘脑＞小脑＞扣带回＞额叶＞顶叶＞颞叶＞海马的趋势，动脉血药浓度明显高于脑组织药物浓度，而静脉血药浓度则低于脑组织药物浓度。结论 异丙酚在由动脉向脑组织的转运过程中存在延迟现象。 异丙酚麻醉时在中枢不同区域分布不同，其中脑干和丘脑最高，脑干和丘脑可能在异丙酚静脉麻醉中发挥着重要作用。     

脑出血大鼠急性期血浆及脑匀浆神经肽Y活性的变化

目的　观察大鼠脑出血急性期血浆及脑匀浆中神经肽 Y (NPY)活性的动态变化 ,探讨 NPY在脑出血脑损害中的作用。方法　 Wistar大鼠 70只 ,随机抽签法分为脑出血组及假手术对照组 ,每组各 35只 ;每组再按出血前及出血后 0 .5、6、12、2 4、4 8和 72 h分为 7个亚组 ,每亚组 5只。分别于各时间点测定血浆和血肿周边脑组织 NPY含量 ,并观察血肿病灶区的组织形态学病理改变。结果　脑出血后 6 h血浆和血肿周边脑组织 NPY的含量开始同步升高 ,并于 2 4 h达峰值 ,4 8h开始回落 ,但至 72 h时 NPY的含量仍显著高于出血前 (P<0 .0 5或 P<0 .0 1)。光镜和电镜下脑组织也发生相应的病理损害。结论　 NPY可能参与了脑出血的病理生理过程。     

丙泊酚效应室靶控输注用于患心血管疾病老年人胃镜结肠镜联合检查的临床观察

目的 观察效应室靶控（TCI）丙泊酚用于患心血管疾病老年患者胃肠镜检查的效果和安全性.方法 合并一种以上心血管疾病的拟行择期胃镜＋结肠镜检查的患者40例（年龄60-80岁）,分为TCI组和TIVA组（n=20）,分别以效应室浓度2.5 μg/ml靶控输注和1-1.5 mg/kg初始量＋5 mg/kg/h恒速输注丙泊酚.记录术中循环情况,苏醒时间,并发症,丙泊酚用量和患者满意度.结果 两组患者均顺利完成检查,TCI组术中循环波动幅度小,用药量少,术中体动、低氧等并发症少,两组患者在苏醒时间上无差异,而均未出现术后恶心呕吐和术中知晓.TCI组的苏醒时效应室浓度为0.96±0.23μg/ml.结论 Ce=2.5 μg/ml的效应室靶控模式输注丙泊酚用于合并心血管疾病老年患者胃镜＋肠镜联合检查麻醉效果确切,维持剂量少,安全有效.     

The influence of sevoflurane on the bispectral index, regional cerebral oxygen saturation, and propofol concentration during propofol/N2O anesthesia

Objective This study was undertaken to investigate the influence of sevoflurane on the bispectral index (BIS), regional cerebral oxygen saturation (rSO₂), and serum propofol concentration during propofol/N₂O anesthesia. This study tested the hypothesis that sevoflurane affect BIS values, rSO₂, and the pharmacokinetics of propofol during propofol/ N₂O anesthesia.Methods General anesthesia was administered to 15 ASA I-II patients with a continuous infusion of propofol to maintain a BIS value of 45 ± 5. After recording baseline values, patients were assigned to receive sevoflurane (2.0%, 20 min). BIS values, rSO₂ using near-infrared spectroscopy, and hemodynamic parameters were recorded for 60 min. Cardiac output (CO) and stroke volume (SV) were evaluated using impedance cardiograph methods. Propofol concentration was determined using high-performance liquid chromatography.Results Sevoflurane (2.0%, 20 min) decreased the BIS score from 47.4 ± 8.2 to 27.3 ± 5.9 (P < 0.01, n = 15) without affecting rSO₂. Sevoflurane decreased systolic blood pressure from 112.1 ± 14.0 mmHg to 96.5 ± 13.2 mmHg (P < 0.001, n = 15) without affecting heart rate. Both CO and SV were significantly decreased during sevoflurane application. Propofol concentration was increased from 2.71 ± 0.51 μg/ml to 3.30 ± 0.57 μg/ml (P < 0.05) after sevoflurane application, and was returned to baseline after sevoflurane washout.Conclusions We have shown that sevoflurane decreases BIS values during propofol/N₂O anesthesia without affecting rSO₂ and that this change is accompanied by an increase in serum propofol concentration. Changes in propofol concentration may be due to, at least in part, hemodynamic changes such as decreased CO produced by sevoflurane.A part of the present study was presented at the Annual Meeting of the American Society of Anesthesiologists, October 23–27, 2004 in Las Vegas, Nevada, USA.Nishikawa K, Kanemaru Y, Hagiwara R, Goto F. The influence of sevoflurane on the bispectral index, regional cerebral oxygen saturation, and propofol concentration during propofol/N₂O anesthesia.     

浅麻醉下犬脑组织对异丙酚的摄取及其分布

目的:研究异丙酚浅麻醉时在犬脑不同区域的摄取及分布。方法:6条成年雄犬,静脉注射异丙酚4.5mg/kg,达到有效麻醉深度后3min,取颈内动脉和颈内静脉血并断头法将犬处死,解剖犬脑,分别取额叶、顶叶、颞叶、海马、扣带回、丘脑、中脑、桥脑、小脑组织。高效液相色谱-紫外线法测定血浆浓度及组织浓度。结果:各个脑区药物浓度分布呈桥脑>中脑>丘脑>小脑>扣带回>额叶>颞叶>顶叶>海马的趋势,动脉血药浓度明显高于静脉血药浓度。结论:异丙酚浅麻醉时在犬脑不同区域分布不同,其中以脑干和丘脑最高,可能在异丙酚静脉麻醉中发挥着重要作用。     

开胸手术异丙酚血药浓度与脑电和心率变异的相关性研究

目的　探讨异丙酚静脉麻醉血药浓度与脑电和心率变异的相关性。方法　选择 10例开胸手术患者行异丙酚静脉麻醉复合胸段硬膜外阻滞。应用高效液相色谱法测定术中和术后不同时相患者异丙酚的血清浓度 ,记录数量化脑电图和心率变异的变化。结果　在插管、切皮和关胸时脑电BIS和SEF值均显著低于麻醉前 (P <0 0 5或 P <0 0 1)。心率变异Tp值在切皮和关胸时显著低于麻醉前 (P<0 0 1)。术后 15min内脑电BIS值与异丙酚血清浓度呈高度负相关 ,心率变异TP值与异丙酚血清浓度呈中度负相关。结论　BIS可作为判断静脉麻醉深度的指标 ,Tp则为参考指标。     

一氧化氮在颅脑损伤手术麻醉期间含量变化及异丙酚的保护作用

目的 探讨急性颅脑损伤（ACI） 患者围术血浆一氧化氮（NO）、一氧化氮合成酶（NOS）、氧自由基（OFR）、脂质过氧化物（LPO）、内皮素（ET）、降钙素基因相关肽（CGRP）含量变化及新型静脉麻醉剂异丙酚（Pro）对其影响。方法 ACI患者40例,根据麻醉方法不同随机分为观察组（异丙酚组）和对照组（α-羟基丁酸钠组）。观察麻醉诱导前、开颅手术去骨瓣后1、3、6、12、24hNOS/NO(分别用T0－T5表示）;麻醉诱导前、开颅手术后1、3hOFR/LPO`ET/CGRP的水平变化。结果 研究发现术前患者血中NO、NOS均高 于正常对照组,其中NOS显著增高;血中OFR、LPO、ET显著高于正常对照组。与对照组相比异丙酚组NO、NOS自妈至经科（T0－T5）呈降低趋势。NOS于开颅手术后1h(T1)达到正常水平,NO于T2时也达到正常水平。FOR、LPO、ET呈显著降低趋势且于T2时达到正常水平。CGRP呈持续升高。结论 ACI患者术前就存在OFR代谢紊乱及NO／NOS、ET／CGRP间含量失衡,开颅手术可导致继发性脑缺血再灌注损害。临床麻醉剂量的Pro具有非选择性NOS抑制剂、OFR清除剂、ET拮抗剂特性,并能提高CGRP水平,具有多途径、多位点脑保护剂特性。     

丙泊酚不同靶浓度靶控输注用于老年患者结肠镜检查的临床观察

目的 比较丙泊酚不同靶浓度靶控输注在老年患者结肠镜检查中的麻醉效果及不良反应。方法 64例行无痛结肠镜检查的老年患者随机分为3组：A组（n=22）、B组（n=22）、C组（n=20）。3组患者丙泊酚血浆靶浓度分别设置为4、5和6μg／mL。分别记录3组患者入室时、插镜时、停止注药时、睁眼时的SpO2、BP、HR．和BIS值，开始注药到镜检开始时间（T1）、开始注药到停止注药时间（T2）、镜检时间（T3）、停止注药到睁眼时间（T4），诱导量（D1），总用药量（D2），并记录不良反应。结果 C组插镜时和停止注药时的MBP低于其他两组（P〈0.05）；T1时间C组明显缩短（P〈0.05），C组丙泊酚的诱导量高于其他两组（P〈0．05），不良反应发生率亦较高。结论该研究表明，丙泊酚4.5μg／mL血浆靶浓度用于老年患者结肠镜检查较为适宜，不良反应发生率较低。     

Cardiac arrhythmia during propofol sedation

Recent articles have described the increasing frequency of use of propofol as a sedating agent in the ED, and praise the safety profile of propofol when used in this manner. We describe a patient who developed torsade de pointes followed by ventricular fibrillation while undergoing propofol sedation for closed reduction of a mid‐shaft fracture of the tibia and fibula. Possible reasons for the event are discussed, and suggestions are made for areas of further research.     

Influence of the ORM1 phenotypes on serum unbound concentration and protein binding of quinidine

BACKGROUND: Only unbound or free drug in plasma can be transported to its site of action. The fraction of unbound drug in plasma varies widely for highly bound drugs among individuals. The genetic polymorphism of orosomucoid (ORM) could be related to the interindividual variability in plasma binding of basic drugs, as ORM is the transport protein for these drugs in plasma. The ORM is a major binding protein in plasma for various basic drugs and is coded by two loci, ORM1 and ORM2, which are closely linked on chromosome 9q31-->34.1. ORM1 locus is highly polymorphic and the ORM2 locus is monomorphic in most population. METHODS: Twenty-eight healthy volunteers were selected with three ORM1 phenotypes, containing homozygotes ORM1 F1 (n=10) and ORM1 S (n=8), and heterozygote ORM1 F1S (n=10), identified by isoelectric focusing on polyacrylamide gels followed immunoblotting after desialylation of sera. After a single oral dose of quinidine 200 mg, serum total (HPLC) and unbound concentrations in ultrafiltrate (ultrafiltration/HPLC) were determined, and the pharmacokinetic parameters and protein binding rate were calculated. RESULTS: Serum concentrations of ORM (553.8-573.2 mg/l) and albumin proteins (57.5-58.4 mg/l) were similar in the three groups (P>0.05). Unbound quinidine concentration in ORM1 F1 phenotype subjects was higher than that in ORM1 S and ORM1 F1S phenotype; the free drug percentage for the subjects with ORM1 F1 phenotype (19.79%) was twice as high as that with ORM1 S phenotype (10.96%) (P<0.01) at 24 h after administration of oral quinidine when the state of disposition equilibrium occurred. The elimination t(1/2) values and the other pharmacokinetic parameters of quinidine were not affected by the different ORM1 phenotypes. CONCLUSIONS: Different ORM1 phenotypes may affect the disposition of quinidine, a basic drug, rather than its hepatic metabolism and elimination. The functional heterogeneity of ORM1 could be responsible for the differences in plasma binding of quinidine. Therefore, monitoring of the unbound quinidine concentration would be important for the patients with different ORM1 phenotypes who are treated with quinidine.     

Influence of the unbound concentration of cefonicid on its renal elimination in isolated perfused rat kidneys.

The effect of variations in plasma protein binding on the renal excretion of cefonicid was assessed by using isolated perfused rat kidneys. Cefonicid exhibits preferential binding ex vivo to human serum albumin (HSA), as opposed to bovine serum albumin (BSA), and is eliminated mainly by tubular secretion, a process that was reported to be dependent on the total drug concentration. This contradicts previous studies with antimicrobial compounds and other drugs of low renal extraction in which the unbound drug concentration was shown to be the driving force for carrier-mediated tubular transport. To clarify this discrepancy, we performed perfusion studies by using 6% BSA at initial concentrations of 200 micrograms/ml (n = 6) and 20 micrograms/ml (n = 9) and in a combination of 4% BSA plus 2% HSA at initial concentrations of 200 micrograms/ml (n = 4). The excretion ratio [ER = CLR/(fu x GFR)] of cefonicid decreased with increasing unbound concentrations, whereas no apparent relationship with the total concentration was evident. At similar total concentrations of cefonicid, the renal clearance remained unchanged; the secretion clearance increased significantly in the 4% BSA-2% HSA experiments, reflecting the reduced unbound fraction and unbound drug concentration of cefonicid. The excretion ratio data were compatible with a model in which Michaelis-Menten kinetics were required to describe active transport and secretion was dependent on the unbound cefonicid concentration. As a result, changes in plasma protein binding as a result of drug interactions or disease states could significantly influence the tubular transport capability of compounds with low renal extraction.