Measurement of L-carnitine and acylcarnitines in body fluids and tissues in children and in adults

We have developed a reliable and validated radio-enzymatic method for the assay of L-carnitine and acylcarnitines, using a modification of existing methods. The sensitivity of the assay is 10 mumol/l using 10 microliters of plasma or urine. It is also suitable for measurements of carnitine in a 10 mg sample of liver or muscle obtained by percutaneous biopsy. The use of N-ethylmaleimide in the reaction mixture together with an excess of [1-14C]acetyl CoA ensures that the reaction proceeds to completion and a linear response is obtained. Using this method control ranges have been established for plasma and urine carnitine concentrations in healthy children and adults, and for the carnitine content of liver and muscle in adults. No significant difference was found between fasting and post-prandial plasma carnitine levels. An age-related increase was found in urinary total carnitine and acylcarnitine concentration throughout childhood. These data provide a reliable basis for studies of patients with abnormal carnitine and acylcarnitine metabolism, distribution and excretion.     

Activity of amikacin and ampicillin in succession and in combination

One strain each of Escherichia coli and Streptococcus faecalis were exposed to amikacin and ampicillin in combination as well as in succession. Exposure to ampicillin for 1 hr followed by amikacin for 3 or 4 hr had the greatest antibacterial activity when the antibiotics were applied in succession. The least effective exposures for both organisms were 1 hr to amikacin followed by 3 or 4 hr to ampicillin. Exposure to the antibiotics in combination each at 1 MIC had the overall greatest antibacterial activity. Simultaneous exposure to the antibiotic combination does not necessarily mean simultaneous activity of both ampicillin and amikacin on the E. coli. The cell wall autolytic activities produced by ampicillin are triggered within 10 min after physical contact with the bacteria. In contrast, amikacin requires at least 30 min after physical contact to manifest its activity on the ribosome. Although physical exposure to both antibiotics in the combination is simultaneous, the specific activity of each is in fact sequential, with ampicillin acting first. This explains the synergistic effect of the combination. It appears, therefore, that the synergistic or antagonistic affect of a drug combination is determined by the sequence and timing of the antibacterial manifestations of its components.     

纤维支气管镜在儿童咯血诊断与治疗中的应用

目的 评价纤维支气管镜术在儿童咯血病因诊断及治疗中的价值以及安全性.方法 应用用日本产Olympus BF 3c-40纤维支气管镜(最小外径3.6 mm)给58名咯血原因不明的患者行纤维支气管镜检查,并予镜下局部止血治疗.判断出血部位、观察病变情况和出血的原因、临床表现、其他辅助检查、治疗及转归等进行综合分析.结果 引起咯血的主要疾病为气管支气管、肺部的炎症24例(41.3%)、支气管内膜结核12例(20.7%)、支气管异物8例(13.7%)、特发性肺含铁血黄素沉着症7例(12.1%)、支气管扩张4例(6.9%)、心肺血管发育异常1例,原因不明2例.诊断阳性率为96.5%.镜下发现有活动性出血18例,镜下局部止血治疗后显效者10例,有效者8例,有效率为100%.术中并发短暂低氧血症(SaO2＜85%,＜20 s)15例,加大吸氧流量后均改善;术后发热3例均为低热,24 h后热退.结论 纤维支气管镜检查可明确出血部位及原因并可进行局部治疗,且安全的有效.     

Sites of in vivo extraction and interconversion of testosterone and androstenedione in dogs

The interconversion and extraction of testosterone and androstenedione across and within different tissues or areas have been studied by the constant infusion technique. The results were calculated using the (3)H/(14)C ratios and radioactive concentrations of testosterone and androstenedione obtained from afferent and efferent blood and tissues at equilibrium. In each tissue studied, the interconversion between testosterone and androstenedione inside the tissue was significantly higher than the corresponding interconversion across the tissue. The pulmonary contribution to the total interconversion between testosterone and androstenedione was far more important than that of any of the other tissues studied. The hepatic metabolic clearance rates of testosterone and androstenedione were not different from their metabolic clearance rates in the mesenteric area. The extraction of each of these compounds, although not negligible, was lower in the kidney and the femoral bed compared with the extraction in the liver and the mesenteric area. Finally, with the possible exception of the liver, testosterone and androstenedione were more completely metabolized when they originated from the cells than from afferent blood.The evaluation of these different tissue transfer constants provides more precise information concerning the relative importance of different sites in the metabolism of these interconverting hormones.     

Evaluation of aprotinin and tranexamic acid in different in vitro and in vivo models of fibrinolysis, coagulation and thrombus formation

BACKGROUND: The serine protease inhibitor aprotinin and plasminogen inhibitor tranexamic acid are used in coronary artery bypass graft (CABG) surgery to reduce bleeding. Clinicians may consider these agents as readily substitutable regarding their pharmacological profiles. OBJECTIVE: These agents were evaluated in assays of hemostasis to elucidate their underlying mechanism(s) of action. METHODS: In human plasma, effects on both clot fibrinolysis and coagulation were spectrophotometrically quantified in vitro. Rat-tail bleeding and arteriovenous shunt thrombus formation models were conducted in vivo. RESULTS: Fibrinolysis was inhibited by aprotinin (IC(50), 0.16 +/- 0.02 micromol L(-1)) and tranexamic acid (IC(50), 24.1 +/-1.1 micromol L(-1)). In vivo, aprotinin dose-dependently reduced rat-tail bleeding time (minimal effective dose, 3 mg kg(-1) bolus plus 6 mg kg(-1 )h(-1) infusion); tranexamic acid reduced bleeding time (minimal effective dose, 100 mg kg(-1) h(-1)). In vitro, coagulation time was doubled by aprotinin at 3.2 +/- 0.2 micromol L(-1), while tranexamic acid showed no effect at concentrations up to 3 mmol L(-1). Aprotinin inhibited thrombus formation in vivo in a dose-dependent manner (minimal effective dose, 3 mg kg(-1) bolus plus 6 mg kg(-1) h(-1) infusion). Conversely, tranexamic acid dose-dependently increased thrombus formation and thrombus weight (minimal effective dose, 100 mg kg(-1 )h(-1) infusion). CONCLUSIONS: These data show that aprotinin and tranexamic acid have differential effects on hemostasis and are not necessarily substitutable with respect to mechanism of action. Although both agents have been shown to reduce bleeding in patients undergoing CABG, their divergent effects on thrombus formation observed in vitro and in vivo should be critically evaluated clinically.     

Noradrenaline and Adrenaline in Blood and Urine in a Case of Phaeochromocytoma

A case of phaeochromocytoma is described in which X-ray investigation and pharmacodynamical tests with tetraethyl-ammonium and Regitin were non-informative. The diagnosis was established by the increased excretion of catechols with the urine (1010–2400 μg noradrenaline and 16–19 μg adrenaline per 24-hour period).

Estimation of catechols in samples of the blood and of the urine from the same period showed an average blood level of 3.6 μg/100 ml noradrenaline and a corresponding urinary output of 110 μg per hour.

The high systolic and diastolic blood pressure, the electrocardiographic changes, the increased basal metabolic rate, the response to the glucose tolerance test, sweating, eosinopenia and fatigue are explained as symptoms and signs of hypernoradrenalinemia.

Biological estimation of the catechols in the tumor, which weighed 40 g, showed 590 μg/g noradrenaline and 12 μg/g adrenaline.

After operation the blood pressure and the level of the urinary catechols returned to normal.     

Population pharmacokinetics and pharmacogenetics of alcohol in Chinese and Indians in Singapore

What is known and Objective:  Interindividual variability in alcohol pharmacokinetics is influenced by a number of factors, including polymorphisms in genes mediating alcohol pharmacology, ethnicity, sex and body size. Several studies have evaluated the population pharmacokinetics of alcohol from breath alcohol measures. None of these studies, however, have evaluated ethnicity and alcohol‐metabolizing enzyme genotypes as covariates in their population pharmacokinetic modelling. We aimed to develop a population pharmacokinetic model using clinical and genetic factors and to identify covariates that influenced interindividual variability in alcohol clearance and volume of distribution. Methods:  Hundred and eighty healthy subjects (90 Chinese and 90 Indians; 45 males and 45 females from each ethnic group) ingested a vodka–orange juice mixture to simulate social drinking. Subjects were genotyped for the ADH1B (Arg48His), ALDH2 (Glu504Lys) and CYP2E1 (c.‐1293G>C and c.‐1053C>T) polymorphisms. A base pharmacokinetic model was developed using the nonmem software (NONMEM Project Group, University of California, San Francisco, San Francisco, CA, USA) to determine the alcohol clearance and volume of distribution. The model was extended to include covariates that influenced the between‐subject variability. Results and Discussion:  Body weight and sex significantly influenced absorption rate and volume of distribution of alcohol. Body weight and ADH1B Arg48His polymorphism significantly influenced alcohol clearance. The Michaelis–Menten elimination rate (V_max) was decreased by 10% in homozygous ADH1B*1/*1 subjects. Ethnicity was not determined to be a significant covariate in the final population pharmacokinetic model. What is new and Conclusion:  Gender and body weight were covariates that contributed most to explaining the observed interindividual alcohol pharmacokinetic variability. Of the four SNPs examined in this study, only ADH1B Arg48His polymorphism had a significant, though modest, effect on the pharmacokinetics of alcohol.     

Safety and efficacy of linezolid in 16 infants and children in Japan

Linezolid, an oxazolidinone antibiotic, exhibits a broad spectrum of activity against Gram-positive bacteria. It has been licensed for adult use in Japan since 2006 for MRSA infections, and has also been used off-label for pediatric patients. At our university hospital, a total of 16 infants and children (including one non-Japanese Asian) were administered linezolid owing to infection with multidrug-resistant Gram-positive bacteria, after consent had been provided. All patients had severe underlying diseases or indications for surgery. Eighty-eight percent of the causal microorganisms were methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant coagulase-negative Staphylococcus and all were sensitive to linezolid. Linezolid was administered because the antecedent anti-MRSA medications were ineffective or contraindicated, or intravenous-to-oral switch therapy was requested owing to cardiac or orthopedic surgical-site infections. The median duration of administration was 13 days (range 3-31 days). The overall efficacy was 91 % (10/11) in those for whom efficacy could be evaluated. Only two patients (both teen-aged) encountered linezolid-related adverse effects (13 %, 2/16). One patient showed elevation of liver enzymes (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]), requiring that administration be withdrawn, but enzyme levels returned to normal after the patient had been switched to vancomycin. The other patient showed transiently decreased platelet counts. Linezolid is considered generally safe and effective for children in Japan, especially for those who cannot use other anti-MRSA medications or those who require oral antibiotics for infections with multidrug-resistant Gram-positive bacteria.     

血浆与血清同型半胱氨酸在不同检测条件下比较及稳定性研究

目的分析同型半胱氨酸(Hcy)水平在血浆与血清中的差异及放置不同时间检测的稳定性。方法分别以EDTA-K2抗凝管和分离胶管收集42例健康体检人员血液,于即刻及放置3h后分离血浆及血清。选EDTA-K2抗凝管立即离心分离血浆后于室温放置1h、3h、6h及2-8℃24h;分离胶管放置30min待血液凝固后离心分离血清于室温放置1h、3h、6h及2-8℃24h,使用直接化学发光法检测同型半胱氨酸浓度。结果分离胶管取血放置30min后离心分离血清同型半胱氨酸浓度较即刻分离的血浆同型半胱氨酸浓度高13.24%,结果差异有统计学意义(P<0.05);取血放置3h后离心检测血清或血浆同型半胱氨酸浓度明显高于取血后即刻离心检测的同型半胱氨酸浓度,两者相差12.47%和12.56%,结果差异有统计学意义(P<0.05)。分离后血浆与血清在室温放置1h、3h、6h及2-8℃24h检测同型半胱氨酸浓度,结果差异均无统计学意义(P>0.05)。结论血清同型半胱氨酸水平明显高于血浆,分离血清或血浆前标本放置时间对检测同型半胱氨酸浓度有影响,分离后血浆或血清在2-8℃保存,24h内同型半胱氨酸检测结果差异无统计学意义。在临床工作中,应尽可能快速分离血浆标本进行同型半胱氨酸检测或分别设立血浆与血清同型半胱氨酸浓度的正常参考范围。     

Role of oxidants and antioxidants in atherosclerosis: results of in vitro and in vivo investigations

Both in vitro and in vivo studies have shown that oxidants are central in the development of atherosclerosis. Consequently, additional studies evaluated the protective effects of various natural and synthetic antioxidants, alone and in combination, with most studies focusing on alpha-tocopherol (vitamin E). Here, we summarize the role of oxidants in the pathomechanism of atherosclerosis. We also discuss epidemiological studies and others focused on the protective effect of vitamin E against atherosclerosis. Other antioxidants are also considered if they were included in studies involving vitamin E. The protective effect of antioxidants on atherosclerotic pathomechanisms has been confirmed in vitro, but only in some animal studies. Various epidemiological and observational studies have produced conflicting results on the protective effect of antioxidants. Most studies of primary or secondary prevention failed to show a protective effect. These conflicting results are biased by a number of factors, including differences between the study groups. Therefore, we describe these studies in detail.     

肿瘤微环境中外泌体在肿瘤发生发展中作用及机制

外泌体(exosomes)是直径在30~100 nm,内含RNA、脂质和蛋白质的纳米级囊泡,来源于细胞内溶酶体微粒内陷形成的多囊泡体,与细胞膜融合后释放到胞外,是肿瘤微环境中细胞间通讯和遗传物质的重要载体。肿瘤在发生、发展过程中可通过外泌体与肿瘤微环境中的免疫细胞、内皮细胞和肿瘤相关成纤维细胞之间相互作用从而促进肿瘤的进展,其携带蛋白质、脂质和核酸等内容物释放到细胞外随着体液运输改变肿瘤微环境、促进肿瘤细胞增殖、加快血管形成及促进癌症发展;肿瘤微环境是由肿瘤细胞、巨噬细胞、成纤维细胞及细胞外基质等共同构成的局部稳态环境,在癌症的发生、复发、转移和化疗耐药等过程中发挥重要的作用。本综述着重讨论外泌体的生物学特性及对肿瘤微环境的影响,为研究及诊断治疗肿瘤提供新的思路。     

Pharmacokinetics and tolerance of flunitrazepam in neonates and in infants.

OBJECTIVE: To study the pharmacokinetics of flunitrazepam (used for sedation in neonates and infants), to determine the influence of both gestational and postnatal age on the pharmacokinetic parameters, and to analyze the relationship between the hemodynamic parameters and flunitrazepam plasma concentration. METHODS: Flunitrazepam was infused for 20 minutes as a single dose (0.2 mg x kg(-1)) and as multiple doses (0.1 mg x kg(-1)). Six to eight 1-mL blood samples were collected per patient. Flunitrazepam plasma concentration was measured by gas chromatography-mass spectrometry. RESULTS: Thirty-one patients (25 neonates and six infants) were included in the study. Only three of them received multiple doses. After the single dose (n = 28), half-life was 22.6 +/- 7.3 hours, clearance was 0.15 +/- 0.14 L x kg x h(-1), and volume of distribution was 4.6 +/- 4.1 L x kg(-1) (mean +/- SD). Plasma clearance and volume of distribution significantly increased with postnatal age (P < .05), but no pharmacokinetic parameter varied significantly with gestational age. Diastolic blood pressure significantly decreased with increasing flunitrazepam plasma concentrations (P < .05). CONCLUSION: Postnatal age but not gestational age influenced flunitrazepam pharmacokinetic parameters in neonates and infants. Diastolic blood pressure was inversely correlated to flunitrazepam plasma concentration.     

Assessment of fatigue in cancer and non-cancer patients and in healthy individuals

Fatigue is a very complex phenomenon. It has been described as a major distressing symptom in cancer patients. It is a multidimensional experience that focuses not only on biochemical or pathophysiological causes, but also involves psychological and behavioural aspects. Until today, measurement of fatigue has been a neglected topic in medicine and nursing and a nihilistic attitude still prevails. The lack of valid, reliable tools of measurement is one of the problems inhibiting further research. Only recently has quality- of-life research begun to acknowledge this phenomenon and include fatigue in assessment. In this study, fatigue was measured and explored in cancer patients non-cancer patients and in healthy individuals. A clear distinction evolved between healthy fatigue in healthy individuals and unhealthy fatigue in cancer patients, where the impact of fatigue was far more negative. Characteristic fatigue profiles underlined these findings. The new visual-analogue fatigue scale, to measure fatigue four times daily, proved to be very useful. Further research is needed to develop therapeutic strategies and to support the patients who have to cope with this distressing symptom.Presented as an invited lecture at the 4th International Symposium: Supportive Care in Cancer, St. Gallen, Switzerland, 24–27 February 1993     

Correlation of in vivo and in vitro functions of fresh and stored human platelets

BACKGROUND: Long-term storage of human platelets has been hindered by the loss of function of the platelets stored under current protocols. Novel preservation methods have encouraged examination of platelet function of cells preserved by cooling and freezing. The function of the platelets was assessed by using both in vitro assays and an in vivo rabbit bleeding model. STUDY DESIGN AND METHODS: Human platelets were stored in the presence or absence of 2 microM: cytochalasin B and 80 microM: EGTA/AM at 4 degrees C for 14 days or by freezing in the presence or absence of 5 percent DMSO. After the storage period, the platelets were resuspended in normal saline and infused into rabbits. Platelet function was assessed in vivo in a kidney bleeding model and in vitro by platelet-induced clot retraction and by platelet aggregation. RESULTS: Platelets stored at either 4 degrees C or -145 degrees C exhibited shorter survival times in the rabbit circulation than did fresh platelets. Platelets cooled to 4 degrees C, in both the presence or absence of cytochalasin B and EGTA/AM treatment, or frozen in the absence of DMSO were not effective in halting bleeding. However, frozen DMSO-treated platelets were as effective as fresh platelets in stopping bleeding. In vitro assays showed that cooled platelets treated with cytochalasin B and egtazic acid/AM and frozen DMSO-treated platelets retained 30 to 40 percent platelet function, while the cooled and frozen control samples exhibited no platelet-induced clot retraction. With thrombin as the agonist, only frozen DMSO-treated platelets exhibited a tendency to aggregate, although at only 22 percent of the aggregation function of fresh platelets. CONCLUSION: It is possible to freeze platelets and retain in vivo efficacy if the cryopreservative DMSO is included in the preparation. In vitro responses were greatly reduced by all of the storage protocols, but it may not be necessary to retain 100 percent in vitro function to have a platelet substitute or storage product that functions satisfactorily in vivo.     

C-反应蛋白及铁蛋白检测在判断胸腹水性质中的应用

目的探讨C-反应蛋白、铁蛋白检测在判断胸腹水性质中的价值。方法对100例胸腹水（渗出液75例、漏出液25例）患者,采用美国奥林帕斯AU-2700全自动生化分析仪进行C-反应蛋白测定,采用BACKMANCOULTER Access2全自动发光仪进行铁蛋白测定。结果漏出液中C-反应蛋白和铁蛋白的含量分别为（3.4±1.3）mg·L-1和（75.3±34.2）μg·L-1,渗出液中C-反应蛋白和铁蛋白的含量分别为（18.1±7.5）mg·L-1和（269.8±74.3）μg·L-1,渗出液中C-反应蛋白和铁蛋白的含量明显高于漏出液（均P〈0.01）。结论 C-反应蛋白与铁蛋白在渗出液与漏出液中的含量存在显著差异,其检测有助于鉴别渗出液和漏出液。