血气分析仪标准溶液定值器的研制

血气分析仪标准溶液定值器是基于Poiseuille定律研制。二氧化碳气体和空气中的氧气在仪器气体混合单元中充分、均匀混合成一定比例的气体，再和标准物质溶液混合，配制出血气分析仪检定用标准溶液。     

亚低温冬眠疗法治疗重度脑挫伤的临床研究

目的探讨亚低温冬眠疗法对重度脑挫伤病人的脑保护机理及临床疗效。方法46例重度脑挫伤患者(GCS≤8分)随机分为亚低温冬眠治疗组和常温治疗组。其中亚低温冬眠组22例,入院后4￣12h内行亚低温冬眠治疗,输液泵持续静脉点滴冬眠合剂,将肛温控制在32￣35℃,亚低温冬眠治疗4￣7d,同时检测颈动脉和颈静脉血气、电解质变化、血糖及生命体征等指标。常温组24例除未行亚低温冬眠治疗外,其余综合治疗及监测方法同亚低温冬眠组。两组病人均于伤后3个月根据GOS预后评分判定疗效。结果与常温组比较,亚低温冬眠治疗组脑氧耗明显降低,高血糖情况显著下降,生命体征及电解质等无明显差异,无严重并发症,死残率明显降低,预后显著改善。结论亚低温冬眠疗法具有显著的脑保护作用,临床应用于重度脑挫伤救治安全有效,无严重并发症。     

Effects of isoflurane on oxygenation during one-lung ventilation in pulmonary emphysema patients

Background: Hypoxic pulmonary vasoconstriction has an important role in human one-lung ventilation (OLV) in the lateral decubitus position under general anesthesia. During OLV, inhalational anesthesia may inhibit hypoxic pulmonary vasoconstriction and the decrease in arterial oxygenation. We studied the effect of isoflurane administration on arterial oxygen tension in chronic obstructive pulmonary disease patients.
Methods: Ten patients who had thoracoscopic laser ablation of bullous emphysema were studied. Patients received 2% isoflurane in oxygen from induction until the first 20 min of OLV in the lateral decubitus position, then were switched to 1% isoflurane lasting 20 min and next were switched to 0.5% isoflurane lasting 20 min. After each 20-min inhalation, pulmonary and hemodynamic parameters were measured. The given concentrations for isoflurane were merely vapor meter concentrations.
Results: PaO₂/FIO₂, Qs/Qt respiratory rate peak inspiratory pressure and PaCO₂ showed no significant changes at each point of isoflurane. Expiratory tidal volume significantly decreased (P<0.05) with 0.5% isoflurane compared to that with 2% isoflurane. Cardiac output, mean arterial pressure, mean pulmonary arterial pressure, systemic vascular resistance and pulmonary vascular resistance showed no significant changes at each point of isoflurane.
Conclusions: In patients with pulmonary emphysema, arterial oxygenation is not affected by low isoflurane concentration during OLV in the lateral decubitus position.     

复方天棘胶囊对老龄鼠血气影响的研究

本研究选用昆明种老龄鼠５０只，随机分为正常对照组、阳性对照组和复方天棘胶囊高、中、低剂量组；每组１０只。观察灌服复方天棘胶囊溶液对实验性老龄鼠血气的影响。结果表明，老龄鼠灌服２．０、１．０和０．５ｇ／ｋｇ体重复方天棘胶囊溶液及５．０ｇ／ｋｇ体重红参水煎液１０天后，复方天棘胶囊各剂量组均有不同程度的升高动脉血氧分压（ＰａＯ＿２）和血氧饱和度（ＳａＯ＿２）的作用；且随剂量的递增，ＰａＯ＿２和ＳａＯ＿２明显升高，其中高剂量组升高ＰａＯ＿２和ＳａＯ＿２的作用最为明显（Ｐ＜０．０１）；红本组ＳａＯ＿２也有明显升高（Ｐ＜０．０１）。提示复方天棘胶囊具有升高ＰａＯ＿２和ＳａＯ＿２的作用。     

Capillary Gas Chromatography and Thermionic N-P-Specific Detection of 13-Bis(2-chloroethyl)-l-nitrosourea (BCNU) or l-(2-Chloroethyl)-3-cyclohexyl-l-nitrosourea (CCNU) in Stability and Pharmacokinetic Studies

An expedient, rapid, and sensitive capillary gas chromatographic method for the analysis of l,3-bis(2-chloroethyl)-l-nitrosourea (BCNU) or l-(2-chloroethyl)-3-cyclohexyl-l-nitrosourea (CCNU) in plasma is described. Separation of the underivatized nitrosourea compounds was performed on a 0.33-mm-i.d., 25-m fused-silica, SE-30 capillary column, and detection was carried out using a thermionic N–P-specific detector. The compounds were extracted from plasma with benzene with a yield of >87%. The assay was linear in the ranges of 0.001 to 0.5 and 0.5 to 25 µg/ml for CCNU or 0.003 to 0.50 and 0.5 to 25 µg/ml for BCNU, with correlation coefficients from 0.9914 to 0.9999 and coefficients of variation (CV) of <3.3%. Other antineoplastic agents did not interfere in the assay. The method was employed to study the pharmacokinetics of BCNU in rabbits. The plasma concentration-time curves were fit to a two-compartment model with a mean (SE) , , and total-body clearance of 2.898 (0.913) hr^–1, 0.1228 (0.0179) hr^–1, and 7.211 (2.862) liters/hr · kg, respectively. Further, the stability of BCNU and CCNU in solution was examined at different temperatures. Both compounds were stable in benzene or acetone (4 to 37°C) but labile in plasma even if refrigerated. The apparent rate constants for degradation of BCNU and CCNU were 0.09921 and 0.02853 hr^–1 at 4°C and 5.998 and 2.553 hr^–1 at 37°C, respectively.     

Determination of tryptamine in rat brain by gas chromatography-mass spectrometry

Tryptamine (TA) occurs in trace levels in the brain, but its role in the central nervous system is not clear. However, there is evidence that TA may be a neuromodulator since it binds to specific binding sites in the brain. TA was measured as a diheptafluorobutyryl derivative in rat whole brain by capillary gas chromatography—mass spectrometry using negative chemical ionization (NCI) and single ion monitoring (SIM). d₄-TA was used as the internal standard. The ions m/z 532 and m/z 536 were monitored to identify TA and d₄-TA, respectively and to calculate the concentration of TA in rat whole brain which was found to be 0.19 ± 0.08 ng g⁻¹ (n = 8). The results confirm the earlier TA concentrations measured by GC—MS using positive electron impact ionization. However, NCI improved the signal/noise ratio of the method increasing its sensitivity for TA.     

Monoamine oxidase inhibition as a sequel of hydrogen sulfide intoxication: increases in brain catecholamine and 5-hydroxytryptamine levels

Administration of sodium hydrosulfide (NaHS), an alkali salt of hydrogen sulfide (H₂S) at doses of 10 and 30 mg/kg, corresponding to sublethal and lethal doses (0.66 and 2.0 X LD₅₀) resulted in significant increases in regional catecholamine levels of the rat brain only after the dose of 2.0 × LD₅₀ of NaHS. Whereas the cortex and the cerebellum showed little or no change in catecholamine content, the hippocampus, striatum and brainstem all showed increases in noradrenaline and adrenaline. Additional analysis also showed that brainstem dopamine and 5-hydroxytryptamine levels (5-HT) increased as well. In vitro testing of sulfide for inhibition of monoamine oxidase (MAO) activity showed the anion to be inhibitory with an IC₅₀ of 39.1±3.6 M. Inhibition of MAO activity ex vivo could be demonstrated at a dose of 100 mg/kg but not at the lower dose of 30 mg/kg NaHS. Inhibition of enzyme activity could not be demonstrated at this lower dose, possibly due to the well known rapid intramitochondrial metabolism of sulfide. Correlation of synaptosomal and mitochondrial sulfide levels with enzyme inhibition data suggests that inhibition of MAO may be an important contributing factor to the mechanism(s) underlying loss of central respiratory drive after fatal intoxication with H₂S.     

A reevaluation of the status of cholesterol in erythrocytes infected by Plasmodium knowlesi and P. falciparum

The cholesterol synthesis of rhesus monkey erythrocytes parasitized by Plasmodium knowlesi and human erythrocytes infected by P. falciparum, as measured by incorporation of [1-¹⁴C]acetate and ³H₂O, was almost undetectable, concordant with very low levels of measurable 3-hydroxy-3-methyl glutaryl-CoA reductase activity. In addition, both types of infected cells exchanged cholesterol with the plasma at the same rate as uninfected cells. The data do not exclude the possibility of cholesterol transfer from uninfected to infected cells.     

Asymmetric and Axisymmetric Constant Curvature Liquid-Gas Interfaces in Pulmonary Airways

Airway closure and gas trapping can occur during lung deflation and inflation when fluid menisci form across the lumina of respiratory passageways. Previous analyses of the behavior of liquid in airways have assumed that the airway is completely wetted or that the contact angle of the liquid-gas interface with the airway wall is 0, and thus that the airway fluid forms an axisymmetric surface. However, some investigators have suggested that liquid in the airways is discontinuous and that contact angles can be as high as 67. In this study we consider the characteristics of constant curvature surfaces that could form a stable liquid-gas interface in a cylindrical airway. Our analysis suggests that, for small liquid volumes, asymmetric droplets are more likely to form than axisymmetric toroids. In addition, if the fluid contact angle is greater than 13, asymmetric droplets can sustain larger liquid volumes than axisymmetric toroids before collapsing to form menisci. These results suggest that (1) fluid formations other than axisymmetric toroids could occur in the airways; and (2) the analysis of the behavior of fluids and the development of liquid menisci within the lungs should include the potential role of asymmetric droplets.