‘Ammonia,lactate and blood gases – A user's guide’

Basic biochemical tests are frequently obtained in acutely unwell neonates and children, as well as in some elective situations. Correct interpretation can be invaluable in identifying rare inherited primary metabolic disorders, but secondary causes of hyperammonaemia, elevated blood lactate or blood gas derangement are more common and require appropriate treatment of the underlying cause. This Personal Practice guide provides an overview of these tests and their interpretation.     

微机判断血气的程序设计和临床应用

将肺心病、慢性肾炎等338例次的血气分析结果输入计算机,应用我们设计的多结果血气判断微机程序判断酸碱紊乱状态,其结果与人工综合判断结果完全相符。而单结果计算机判断和单纯人工判断的结果与人工综合判断结果的符合率分别为88.2％和87.3％。表明多结果计算机判断程序能有效地避免误判、漏判。     

Methionine-induced acidosis in the weanling rat

Whole body balances of non-metabolizable base (NB) were studied in weanling rats fed a cereal-based diet with or without added l -methionine. In response to l -methionine loading (2.5 mmol day^-1) the rats exhibited a significant reduction in rates of food intake (109 vs. 160 g per 8 days) and body growth (3 vs. 52 g per 8 days); fractional oxidation of absorbed dietary amino acid sulphur increased from 0.28 to 0.64; and mean urinary sulphate excretion increased from 2.3 to 14.8 mmol per 8 days. Mean rates of renal excretion of NB and filtered titratable organic acid decreased from 20 to ?11 mmol per 8 days and from 22 to 8 mmol per 8 days. Balances of calcium and NB remained at reference values despite a decrease in whole blood ‘base excess’ from ?1.0 to ?6.4 mmol 1–¹. The concentration of NB in plasma rose but slightly. It is concluded that L-methionine loading in the weanling rat leads to extracellular non-carbonic acidosis subject to renal compensation. This acidosis is due not to retention of H⁺ released by ionization of endogenous sulphuric acid but possibly to accumulation of (acid) organic metabolites of methionine which are efficiently conserved by the kidneys. The rise in sulphuric acid production leads to an adaptive decrease in fractional reabsorption of filtered sulphate. Even during inhibited growth, absorbed dietary NB is retained and deposited in the skeleton, probably as calcium carbonate.     

Synthesis and acid ionization constants of cyclic cystine peptides

Cyclic peptide disulfides of the general formula were synthesized from the corresponding peptide derivatives [Boc-Cys(Trt)(Gly)-_n-Cys(Trt)-OBu^t] by oxidation with iodine in methanol and by subsequent removal of the terminal groups with trifluoroacetic acid. Acid ionization constants of the obtained peptides were determined by potentiometric titration in aqueous KCl (0.1 mol/L) medium. All compounds have two dissociable hydrogens, corresponding to carboxyl (pK¹= 2.35–2.84) and to terminal amino group (pK₂= 5.61–6.93); pK₁, values show first an upward and then a downward trend with the increase in ring size; the opposite is true for pK₂, values. These trends could be tentatively attributed to the intramolecular salt bridge (-COO——-NH⁺₃-) formation.     

非水毛细管电泳法研究进展

非水毛细管电泳作为毛细管电泳法的重要分支已成为研究热点，近年来被广泛应用。综述了非水溶剂的特性及其分子间的相互作用。总结了非水毛细管电泳法中调节和增强选择性的方法和常用检测方法，以及近年来非水毛细管电泳法应用于生物样本代谢产物及药物等方面的研究进展，并展望了其广泛的应用前景。     

复方延胡索颗粒的制备、质控与初步戒毒作用的研究

目的：研究复方延胡索颗粒的制备、质量控制方法、观察该制剂对吗啡依赖鼠的治疗作用。方法：选用黄芪、延胡索、甘草、远志、酸枣仁、石菖蒲、芸香等七种中药组方制备复方延胡索颗粒,以有效部位部性物碱及有效成分四氢帕马丁的含量作为制备方法的筛选指标及复方延胡索颗粒制的质控指标。总生物碱的含量用非水电位滴定法测定,四氢帕马丁的含量以单波长反射锯齿式薄层扫描外标两点法测定,以该中药制剂治疗吗啡依赖性大鼠自然戒断模型体质量变化百分率作为初步戒毒作用的观察指标。结果：四氢帕马丁在1－6μg范围内线性关系良好（r=0.9992)其仪器精密度、同板精密度良好（RSD＜3．0％）,且在显色后0．5－6h内结果稳定,制剂的加样回收率约为975,复方延胡索颗粒中剂量组（0．6g/kg)和高剂量组（1．2g/kg)对吗啡依赖鼠的体质量下降可产生显治疗作用（P＜0．05,P＜0．01）。结论：本制剂一定剂量可有效控制吗啡身体依赖性大鼠戒断后的体质量下降,对吸毒可能有促进康复的作用。     

Chinese-made electrolytic detachable coil in the embolization of a dog aneurysmal model

Objective To develop a Chinese-made electrolytic detachable coil (CEDC) that would allow patients to enjoy the benefit of electrolytic detachable coil without having to rely on the expensive Guglielmi detachable coil (GDC), and to test the safety and efficiency of CEDC. Methods Radiopacity of the marker of the CEDC was tested. The anti-strain force of coils and connection points were measured. In vitro and in vivo electrolyses were conducted. We produced 21 aneurysm models including lateral, bifurcation, and terminal aneurysm models, and embolized 18 models with CEDC. Results Radiopacity of the marker was satisfactory. Anti-strain of the coil and the connection point have shown the safety and efficiency of CEDC. Electrolysis in vitro and vivo, was similar to that of GDC. 83% of the aneurysm models were completely occluded. Coils were found to induce thrombosis in the aneurysm cavity, and could lead to a new endothelium over the entrance of the aneurysm, with organized tissue replacing thrombosis in 2 months. Conclusions CEDC is as efficient and safe as GDC. The marker, the ability to induce thrombosis inside the sac and the growth of new endothelium over the orifice are very satisfactory.     

Contractile force and resting tension in the presence of halothane and increased extracellular potassium or decreased extracellular pH in isolated guinea pig atria

To gain a better understanding of the direct actions of halothane on myocardial function in ischaemia, we studied the effects of increasing extracellular potassium concentration and decreasing extracellular pH (acidosis), alone or in combination with halothane, on the contractile force and resting tension in isolated atria. Guinea pig left atria were superfused with Tyrode’s solution and stimulated at 1 Hz. Isometric contractile force and resting tension were measured using a force displacement transducer. Perfusate potassium concentrations were increased from 5.4 mmol · L⁻¹ to either 8.1 mmol · L⁻¹ or 10.8 mmol · L⁻¹ by adding KCl to the standard Tyrode’s solution, and its pH was decreased from 7.4 to either 7.0 or 6.5 by decreasing bicarbonate. In standard Tyrode’s solution (potassium 5.4 mmol · L⁻¹, pH 7.4), halothane 0.5–2% reduced contractile force in a dose-dependent manner (P < 0.05); the effective concentration of halothane for 50% inhibition of contractile force (IC₅₀) was 1.3%. Both increasing extracellular potassium and decreasing extracellular pH decreased the contractile force in a potassium-or pH-dependent fashion. The negative inotropism of halothane (1%) was not altered by increasing potassium concentrations, whereas 1% halothane caused a greater decrease in contractile force at pH 6.5 than at pH 7.4. Halothane (1%) enhanced the acidosis (pH 6.5)-induced increases in resting tension. Arrhythmias were produced in one of eight preparations during acidosis, while four of eight preparations demonstrated arrhythmias during acidosis in the presence of halothane. These data suggest that acidosis and halothane may have a synergistic interaction on the contractile force and resting tension of the atria. The increase in resting tension observed during acidosis/ halothane conditions suggests than an increase in cytosolic calcium is associated with these synergistic interactions between acidosis and halothane. Pour mieux comprendre l’action direct de l’halothane sur la fonction myocardique pendant l’ischémie, nous avons étudié les effets de l’augmentation du potassium extracellulaire et de la diminution du pH extracellulaire (acidose), seuls ou en association avec l’halothane, sur la force contractile et la tension de repos d’oreillettes isolées. Des oreillettes gauches de cobaye furent perfusées avec une solution de Tyrode et stimulées à 1 Hz. La force contractile isométrique et la tension de repos ont été mesurées avec un transducteur de force de déplacement. Les concentrations de potassium perfusées ont été augmentées de 5,4 mmol · L⁻¹ à 8,1 mmol · L⁻¹ ou à 10,8 mmol · L⁻¹ par l’ajout de KCl à la solution standard de Tyrode, et son pH abaissé de 7,4 à 7,0 ou 6,5 par baisse des bicarbonates. Avec la solution standard de Tyrode (potassium 5,4 mmol · L⁻¹, pH 7,4), l’halothane (0.5–2%) diminue la force contractile proportionnellement à la dose (P < 0,05); la concentration efficace d’halothane requise pour produire une inhibition de 50% de la force contractile (IC_5O) a été de 1,3%. L’augmentation du potassium extracellulaire et la diminution du pH extracellulaire réduisent toutes les deux la force contractile proportionnellement au potassium ou au pH. L’inotropisme négatif de l’halothane (1%) n’est pas modifié par l’augmentation de la concentration de potassium alors que l’halothane produit une diminution plus importante de la force contractile à un pH de 6,5 que de 7,4. L’halothane (1%) exagère l’augmentation de la tension de repos induite par l’acidose (pH 6,5). Des arrythmies sont apparues sur une des huit préparations pendant l’acidose en présence d’halothane. Ces données suggèrent que l’acidose et l’halothane pourraient avoir une activité synergique sur le force contractile et la tension de repos des oreillettes. L’augmentation de la tension de repos observée pendant l’acidose combinée à l’halothane suggère l’association d’une augmentation du calcium cytosolique avec des interactions synergiques entre l’acidose et l’halothane.