Inhalation of amyl nitrite and the measurement of left ventricular outflow velocity: studies in normal, young adults

Amyl nitrite inhalation is useful in the identification of patients with provocable left ventricular (LV) outflow tract obstruction. However, there are no prospective studies that assess the normal change in LV outflow velocity during this intervention. Eighteen normal subjects (mean age, 34+/-5 years; 9 men and 9 women) inhaled amyl nitrite during measurement of LV outflow velocity. Peak velocity increased from 109+/-16 cm/s to 144+/-24 cm/s (P<0.001). There were no significant gender differences in velocity measurements at baseline or at peak. Our study provides prospective data that may be useful when evaluating young adults for LV outflow tract obstruction with Doppler echocardiography during amyl nitrite inhalation.     

亚硝酸钠所致大鼠血清甲状腺激素的变化及维生素E和硒对其影响

给大白鼠喂饲克山病病区粮,并分别向病区粮加维生素 E 和硒,观察亚硝酸钠急性中毒情况下各组大鼠血清甲状腺激素的变化。结果表明,亚硝酸钠可干扰甲状腺正常功能,维生素 E 和硒可不同程度地减轻亚硝酸钠的这种毒性作用。提出除低硒外,亚硝酸盐过多及维生素 E 缺乏在克山病发病中可能有重要作用,需要重视。     

Endothelial Dysfunction in Patients with Noncomplicated and Complicated Hypertension

Endothelial dysfunction plays an important role in the pathogenesis of hypertension. Other risk factors of atherosclerosis also affect its development. The aim of the study was to assess nitric oxide metabolites concentration (nitrites and nitrates No_x) and endothelin (ET-1) in plasma and cyclic 3,5-guanosine monophosphate (cGMP) in 24 h-urine collection in patients with noncomplicated hypertension without risk factors of atherosclerosis and in hypertensive patients with coronary artery disease (CAD). Sixty-eight subjects were included in the study (44 men, 24 women), aged 47 ± 76 years, allotted into four groups: I – controls (18 clinically healthy subjects); II – 12 subjects with hypertension without risk factors of atherosclerosis; III – 16 subjects with hypertension and risk factors of atherosclerosis; and IV – 22 subjects with hypertension and CAD. Plasma NO_x concentration was determined using the Greiss method, plasma ET-1 by ELISA, and urine cGMP using the immunoenzymatic method. Plasma NO_x concentration was 14.00 ± 6.88 μmol/L in group I, in group II – 18.62 ± 5.84 μmol, in group III – 9.96 ± 4.72 μmol/L, and in group IV – 8.78 ± 3.72 μmol/L. Statistically significant differences were between groups I and III (p < 0.05) and I and IV (p < 0.04) and groups II and III (p < 0.01) and II and IV (p < 0.01). The concentration of cGMP in 24 h urine collection was in group I – 40 ± 24 pmol/L; in group II – 54 ± 41 pmol/L; in group III – 38 ± 32 pmol/L; and in group IV – 42 ± 36 pmol/L. There were no significant differences between the groups. Plasma ET-1 concentration was 3.86 ± 0.52 pg/mL in group I, in group II – 4.05 ± 0.71 pg/mL, in group III – 4.22 ± 0.79 pg/mL and in group IV – 4.38 ± 0.75 pg/mL. Statistically significant differences were between group I and III (p < 0.05), I and IV (p < 0.03), and between group II and IV (p < 0.04). Endothelial dysfunction was not found in hypertensive patients without a family history of cardiovascular diseases and without other risk factors of atherosclerosis. Deterioration of endothelial function was observed in patients with hypertension with risk factors of atherosclerosis. It was most pronounced in those with CAD.     

大蒜对氨基比林与亚硝酸钠在大鼠体内所致毒性的预防作用

给Wistar大鼠用氨基比林、亚硝酸钠均以30mg/kg体重的剂量灌胃。实验组于普通饲料中添加10％的生大蒜,阳性对照组饲以普通饲料。对两组大鼠平均每只给予氨基比林和亚硝酸钠的总量分别为171.9mg和167.7mg。实验组在35天实验期中全部存活(12/12),阳性对照组有1只死亡(1/10),2只于濒死时被处死(2/10)。前者血红蛋白含量高于后者(P<0.05),而血清转氨酶活性低于后者(P<0.01),病理检查发现肝脏病变发生率前者为67％(8/12),后者为100％(10/10),大蒜组动物肝脏病变程度显著较阳性对照组为轻,后者除肝脏病变外尚有肺及肾的出血现象。本研究证明,大蒜能阻断氨基比林和亚硝酸钠在大鼠体内形成二甲基亚硝胺,并对其所致的毒害有明显的预防作用。     

预防给药对大鼠硫化氢吸入中毒肺脂质过氧化和抗氧化系统的影响

本文观察了DMAP、NaNO_2、VE、地塞米松、山莨菪碱对大鼠H_2S吸入中毒所致的肺脂质过氧化和天然抗氧化系统改变的预防作用。测定了H_2S中毒后6、12h肺组织及支气管肺泡灌洗液中的MDA,肺SOD,GSH和VE的含量。结果表明,给药组MDA含量显著低于中毒组,其中DMAP,VE和NaNO_2等组的MDA含量与正常无差异(但BALF中VE组,NaNO_2组含量高于正常对照水平,P<0.01)。各组SOD活性增强,GSH、VE的含量增加。上述结果提示这些药物均能在不同程度上降低H_2S中毒时肺自由基的含量。从而减轻因自由基含量升高而引起的肺损伤。提示DMAP,VE,NaNO_2,地塞米松,山莨菪碱等药对大鼠H_2S吸入中毒有预防作用,其中以DMAP,VE,NaNO_2的效果相对较好。     

体外刺玫果汁清除亚硝酸钠及阻断二甲基亚硝胺合成的效果

刺攻果汁和抗坏血酸对亚硝酸钠均具有清除作用,其量与清除率之间存在显著的相关关系(r=0.96和r=0.99),在阻断二甲基亚硝胺合成实验中,刺玫果汁量与阻断率之间也存在相关关系(r=0.88)。两种实验结果表明,刺玫果汁具有明显的清除亚硝酸钠和阻断亚硝胺合成的作用,其主要活性成分可能是抗坏血酸之外的物质。亚硝酸钠清除率和亚硝胺合成的阻断率之间呈正相关(r=0.94),从而认为以亚硝酸钠的清除实验结果可估计亚硝胶合成的阻断程度。     

济宁市售蔬菜中硝酸盐和亚硝酸盐含量分析

对济宁市售８类２７种蔬菜中硝酸盐、亚硝酸盐含量的测定的结果表明：不同种类的蔬菜中硝酸盐的含量差别很大（１４０．６～２７６２．５ｍｇ／ｋｇ），亚硝酸盐的含量在新鲜蔬菜中很低，（０．２０～２．８５ｍｇ／ｋｇ）     

盐酸二甲胺和亚硝酸钠诱发大鼠腺胃粘膜癌前病变

给Ｗｉｓｔａｒ大鼠自由饮用０．０６％盐酸二甲胺和亚硝酸钠的混合水溶液共５６周，大鼠腺胃粘膜肠上皮化生的发生率为８８．９％（４０／４５），其中硫酸粘液阳性肠上皮化生占５５．０％（２２／４０）；轻、中、重度异型增生的发生率分别为４４．５％（２０／４５）、３３．３％（１５／４５）和２２．２％（１０／４５）；胃粘膜腺体囊状扩张的检出率为２８．９％（１３／４５）；无胃腺癌发生。研究结果表明，二甲基亚硝胺的前体物二甲胺和亚硝酸盐能诱发大鼠腺胃粘膜癌前病变，可能为胃癌的病因之一。     

茶叶清除自来水中亚硝酸根方法的研究

生活饮用水（自来水）因供水管长途输送和细菌的作用受到污染，生成对人体极有害的亚硝酸根（ＮＯ－２），每升自来水含有ＮＯ－２０．１０～２．０ｍｇ。实验证明用煮沸的方法不能除去ＮＯ－２。本研究选用茶叶清除自来水中ＮＯ－２，茶叶是一种天然抗氧化剂，它含有抗坏血酸，儿茶素等多种抗氧化剂成分。饮茶能有效地清除饮水中ＮＯ－２，方法简单，效果明显，是一种理想的ＮＯ－２清除方法。     

Methaemoglobin Reduction and NADH-Dependent Methaemoglobin Reductase Activity Following DNBP- and Nitrite Induced Methaemoglobinemia in Sheep

Abstract Haemoglobin, methaemoglobin, and NADH-methaemoglobin reductase were investigated in sheep blood after intraruminal administration of DNBP and sodium nitrite at doses of 45 and 75 mg/kg b. wt., respectively. The sheep suffered from methaemoglobinemia at maximum levels of 5.5–7.5 g MetHb/100 ml blood after about 3 hours. The nitrite-induced methaemoglobinemias were normalized during the first 12 hours, while the DNBP-induced methaemoglobinemias lasted for 2–3 days or more. DNBP also caused serious haemolyses in the sheep after 1–2 days, and two of these animals died. The normal level of methaemoglobin reductase in 10 sheep was 3.3 ± 0.31 units. Nitrite had only a moderate and temporary effect on the reductase enzyme activity, while DNBP had a progressive and almost complete inhibitory effect on the enzyme.