天然冰片在小鼠组织内的GC—MS测定法和组织分布研究

目的：建立天然冰片在小鼠组织内含量测定的GC—MS法并进行组织分布研究，初步探索天然冰片的归经特征。方法：采用DB-5MS弹性毛细管色谱柱（0．25mm×30m×0．25μm）；电子轰击（E1）电离方式，轰击能量为70eV，倍增电压1100V；选择性离子检测（SIM），天然冰片m／z95，内标萘m／z128；小鼠组织样品用生理盐水匀浆后，加入萘作为内标，用正己烷振荡萃取，取上清液进样测定。组织分布研究以天然冰片的CMC—Na溶液给小鼠灌胃，在不同时间点分批处死小鼠后取各组织样本，经处理后用GC—MS法测定组织中的天然冰片含量。结果：本研究建立的天然冰片GC—MS测定方法，在22ng·mL^-1 -22μg·mL^-1范围内响应信号（Y）与天然冰片浓度（X）呈良好线性关系，Y=0．000486X＋0．00036，R^2=0．999（n=3），最低检测限为10ng·mL^-1，定量下限为22ng·mL^-1，日内精密度为3．72—6．11％，日间精密度为7．29～17．6％，相对回收率和提取回收率分别为85．95～107．93％和93．04～103．03％。组织分布研究结果表明，天然冰片分布于大部分组织，单个组织内天然冰片浓度随时间延长呈现多峰现象；天然冰片在肝脏内含量最高，在心、脑、肾等重要组织内的含量也较高。结论：本研究建立的GC—MS测定方法准确、可靠，可用于天然冰片在动物体内的定量分析；天然冰片在不同组织内的分布有明显差异，肝、肾、心、脑中分布含量较高；天然冰片的归经特征中有归心经的趋势。     

人工髋关节置换术后脂肪栓塞综合征的观察与护理

笔者报道人工髋关节置换术后脂肪栓塞综合征的护理措施认为重视氧饱和度及动脉血氧分压监测，注意观察中枢神经系统症状和呼吸系统症状，及时发现并纠止低氧血症，对不同的病人制定不同护理方案，严密观察病情，及时掌握病情变化：是护理的关键。     

[Ca^2＋]i change in hippocampal neurons influenced by preconditioning of etomidate fat emulsion following cerebral ischemia in rats

BACKGROUND: It is known that intravenous anesthetic etomidate fat emulsion has cerebral protection. Now many scholars focus on the research of its cerebral protection from molecular biology, but the mechanism of cerebral protection is still fully unclear. OBJECTIVE: To observe the influence of etomidate fat emulsion on the [Ca2+]i in hippocampal neurons during the transient cerebral ischemia injury in rats. DESIGN: Randomized controlled observation. SETTING: Weifang Medical College. MATERIALS: This study was carried out in the functional laboratory of Weifang Medical College between October 2005 and March 2006. Twenty-four male healthy Wistar rats, aged 3 to 4 months, were involved. Etomidate fat emulsion was provided by the limited company of En-hua Medical Bloc in Jiangsu Province (code of H20020511) and the other agents and materials were provided by Laboratory Center of Weifang Medical College. METHODS: The 24 Wistar rats were randomized into 3 groups: sham-operation group, model group and etomidate preconditioning group, with 8 rats in each. Rat models of transient cerebral ischemia injury were made by the ligation of bilateral carotid arteries combined with descending blood pressure in the latter two groups. Before ischemia (ligation of bilateral common carotid artery), rats in the etomidate preconditioning group were intraperitoneally injected with 12 mg/kg etomidate fat emulsion and then persistently intraperitoneally injected with etomidate fat emulsion at 1.0 mg/kg per minute. Rats in the model group were not administrated. Rats in the sham-operation group were only performed bilateral common carotid artery isolation. When rats were modeled, their brain tissues were quickly taken out and detected. MAIN OUTCOME MEASURES: Change of the fluorescence pixel value of the [Ca2+]i in each group by the laser scanning confocal microscope. RESULTS: Twenty-four rats were involved in the final analysis. Fluorescence pixel value in the sham-operation group was in the low level. Fluorescence pixel value in the model group was significantly higher than that in the sham-operation group (P < 0.01). Fluorescence pixel value in the etomidate preconditioning group was significantly lower than that in the model group (P < 0.01). CONCLUSION: The protection of etomidate fat emulsion to the transient cerebral ischemic injury in rats is associated with the inhibition to the increase of [Ca2+]i to some extent.     

Pressure distribution and perceived comfort in casual footwear

The aim of this investigation was to establish the relationship between short-term perceived comfort and pressure distribution on the dorsal and plantar surfaces of the foot, while walking in a range of commercially available casual footwear. The study was carried out in the biomechanics laboratory of Manchester Metropolitan University using 15 male subjects without foot pathology. Perceived upper and plantar comfort were measured using a specially designed questionnaire, while dorsal and plantar pressure distributions were measured using a rectangular sensor pad recording at 30 Hz and a Mikro-EMED insole recording at 100 Hz respectively. Analysis of variance tests were used to determine differences in perceived comfort and pressure distribution between three pairs of shoes. The findings of this study suggest that an increase in total plantar force and force-time integral may relate to a decrease in perceived plantar comfort. For the three shoes examined in this study, overall peak plantar pressure, the pressure-time integral, and total plantar area did not appear to be linked to perceived plantar comfort. Findings for the shoe upper indicate that decreased dorsal forces and pressures may be related to decreased upper comfort. These findings suggest that the measurement of pressure distribution at the foot-shoe interface could be a useful tool in identifying the causes of discomfort in footwear.     

~(125)Ⅰ眼镜蛇毒及抗眼镜蛇毒血清在小白鼠体内分布的比较观察

用氯胺-T法125I标记眼镜蛇毒示踪液及抗眼镜蛇毒血清。小白鼠分二组，用125I-眼镜蛇毒、125I-抗眼镜蛇毒血清分别给小白鼠尾静脉注射，于注射后的不同时间测定血、颈部肌肉、肝、肺、肾、心等脏器放射性分布。结果发现：125I-眼镜蛇毒在肌肉及肝、肺等器官中于注射后2小时过高峰，在肾脏中浓度高，在脑未见放射性分布，抗眼镜蛇毒血清与眼镜蛇毒分布相似但在肌肉及肺脏有更高的分布。证明抗眼镜蛇毒血清能跟踪分布眼镜蛇毒。     

Reflection on the geographic distribution of multiple sclerosis in France

The geographic distribution of multiple sclerosis within the 95 Départements and the 21 Régions of France was defined from a 1986 nationwide prevalence series derived from questionnaires. This indicated a significant clustering of high frequency regions in the northeastern part of the country with most significantly low areas in the south and west. Distributions were similar to those for MS death rates by Département and Région for 1968–1977, indicating geographic stability over time; but there was also evidence of diffusion over time. The 1986 prevalence distribution was also compared with all published prevalence rates for communities of France. From all these resources we conclude that all of France falls within the "high frequency zone" for MS, that the nationwide prevalence rate is at least 50 per 100000 population, and that there is evidence of geographic clustering of the disease with temporal spread of the cluster.     

Exercise metabolism during 1 hour of treadmill walking while taking high and low doses of propranolol,metoprolol, or placebo

Aerobic exercise and beta-blocking drugs are regularly prescribed as treatment for hypertension and as a prophylactic for patients at risk from coronary heart disease and for those recovering from an infarct. Some beta blockers, particularly non-beta₁-selective drugs, may make exercise more difficult, possibly by interfering with substrate metabolism during exercise. This study examined the effects of low and high doses of a beta₁-selective blocker, metoprolol, and a nonselective beta blocker, propranolol, on exercise metabolism. The study involved 20 healthy subjects (10 men, 10 women) who walked on a treadmill at 50% of their maximal oxygen uptake for 1 h on five occasions, separated by 7 days. On each of the five occasions they received one of the following treatments, given in random order: placebo, metoprolol 50 mg, metoprolol 100 mg, propranolol 40 mg, or propranolol 80 mg, all taken twice daily. Fat oxidation, expressed as a percentage of total energy expenditure, was significantly lower than with placebo for all of the active treatments except metoprolol 50 mg (placebo: 42.7 ± 11.6%; metoprolol 50 mg: 38.7 ± 14.1%, p = NS; metoprolol 100 mg: 36.3 ± 13.7%, p = 0.05; propranolol 40 mg: 31.2 ± 9.3%, p = 0.01; propranolol 80 mg: 29.5 ± 10.9%, p = 0.01); and significantly lower with propranolol than with metoprolol (propranolol 40 mg: p = 0.0036; propranolol 80 mg: p = 0.01). Plasma ammonia concentration was significantly higher than with placebo with propranolol 40 mg, propranolol 80 mg, and metoprolol 100 mg (p = 0.01 for all); with metoprolol 50 mg, there was no difference from placebo (p = NS). Both beta blockers in this study reduced fat metabolism and increased perceived exertion to some degree. Additional inhibition of fat oxidation occurred with the nonselective drug, probably in intramuscular rather than adipose lipolysis, and was probably beta₂ mediated. The results of this study suggest that a selective beta blocker has less of an adverse effect on substrate metabolism than does a nonselective beta blocker. Beta₁-selective drugs may offer advantages in patients who undertake regular aerobic exercise.     

Disposition of 14C-dapoxetine in rats: Complementary experiments with whole-body autoradiographic and tissue dissection techniques

Tissue distribution studies, utilizing whole-body autoradiography and organ dissection techniques, were conducted in male Fischer 344 rats following the oral administration of ¹⁴C-dapoxetine HCl, a potent serotonin reuptake inhibitor. The preliminary study using whole-body autoradiography proved invaluable in locating radioactivity in an organ not usually harvested in a tissue distribution study, namely the preputial gland. Selected organs, based on whole-body autoradiography findings, were dissected from rats and analyzed for radiocarbon content by liquid scintillation counting and for parent drug and N-dealkylated metabolites by extraction and HPLC analysis. Highest concentrations of radiocarbon were observed in the organs of absorption and elimination (ileum, cecum, stomach, duodenum, liver, colon, and kidney) but notable quantities were observed in the lung and preputial and Harderian glands. Most tissues had returned to background radioactive levels 72 h after dosing but persistent concentrations of radiocarbon were present in the preputial gland and liver one week after the single dose of ¹⁴C-dapoxetine. Analysis by HPLC demonstrated the presence of parent drug and N-desmethyl metabolite (nor-dapoxetine) in those organs examined; however, the majority of the radioactivity remained unidentified.     

Na+ currents near and away from endplates on human fast and slow twitch muscle fibers

Fast and slow twitch muscle fibers have distinct contractile properties. Here we determined that membrane excitability also varies with fiber type. Na⁺ currents (I_NA) were studied with the loose-patch voltage clamp technique on 29 histochemically classified human intercostal skeletal muscle fibers at the endplate border and <200 μm from the endplate (extrajunctional). Fast and slow twitch fibers showed slow inactivation of endplate border and extrajunctional I_NA and had increased I_NA at the endplate border compared to extrajunctional membrane. The voltage dependencies of I_NA were similar on the endplate border and extrajunctional membrane, which suggests thatboth regions have physiclogically similar channels. Fast twitch fibers had larger I_NA on the endplate border and extrajunctional membrane and manifest fast and slow inactivation of I_NA at more negative potentials than slow twitch fibers. For normal muscle, the differences between I_NA on fast and slow twitch fibers might: (1) enable fast twitch fibers to operate at high firing frequencies for brief periods; and (2) enable slow twitch fibers to operate at low firing frequencies for prolonged times. Disorders of skeletal membrane excitability, such as the periodic paralyses and myotonias, may impact fast and slow twitch fibers differently due to the distinctive Na⁺ channel properties of each fiber type. © 1993 John Wiley & Sons, Inc.     

Fat metabolism and its response to infusion of insulin and glucose in patients with advanced chronic obstructive pulmonary disease

Summary. In order to investigate fat metabolism and the regulation of lipolysis and blood fuel metabolites by insulin, nine patients with chronic obstructive pulmonary disease (COPD) with chronic hypoxaemia and seven healthy control subjects of similar age were investigated by determination of the turnover rate of free fatty acids (TOR), using 1-¹⁴C-oleic acid as a tracer, and arterial concentrations of FFA, glycerol and 3-hydroxybutyrate. The measurements were performed in the basal state and during insulin and glucose infusion, aiming at euglycaemia at insulin levels of 50 and 100 mU l^-1. The subjects' ages were 64±2.7 and 66±1.1 (mean±SEM) years in the COPD and control groups, respectively. TOR was 0.73±0.06 and 0.52±0.02 mmol min^-1 (P<0.05) in the basal state, 0.33±0.04 and 0.30±0.02 at an insulin level of 50 mU I^-1 and 0.32±0.08 and 0.24±0.02 at an insulin level of 100 mU I^-1, in the COPD and control groups, respectively. Arterial FFA concentration was 0.98±0.08 and 0.75±0.06 mmol 1^-1 (P<0.05) in the basal state in the COPD and control groups, respectively. During the clamp, the decrease in FFA mirrored that in TOR. The results show that the state of lipolysis is increased in severe COPD patients with chronic hypoxaemia. Furthermore, the results suggest a reduced effect of insulin in lipolysis.