An alternative method of nitrous oxide delivery into a minimal-flow circle breathing system

We have sought to define a way in which nitrous oxide can be safely and universally used at minimal to low flows by utilising a circle system with a controlled leak provided by a standard gas analyser sampling line and a fresh gas supply of 50% nitrous oxide in oxygen, entering from a trunk interposed between the ventilator and the circle system. Although preliminary calculations suggested that this arrangement was likely to work, it was found that 13 of 23 patients studied prospectively developed an inspired oxygen fraction below 0.3. We conclude that, although this arrangement provides a new means of introducing nitrous oxide into the circle breathing system, it does not appear inherently safer or more convenient than the conventional route.     

Isoflurane for removal of chest drains after cardiac surgery

Thirty-five patients who had undergone uncomplicated cardiac surgery were randomly allocated to receive either Entonox or isoflurane 0.25% in Entonox as inhalational analgesia for the removal of their two chest drains. The gases were presented premixed in high-pressure cylinders and were self-administered by means of a demand valve. The removal of the second drain was more painful than the first but that pain was better controlled by isoflurane 0.25% in Entonox than by Entonox alone.     

A porcine model for sequential assessments of cerebral haemodynamics and metabolism

We present a physiologically stable porcine model designed for sequential assessments of pharmacological effects on mean hemispheric cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) at sustained normocapnia. The dynamic influence of continuously administered fentanyl (0.040 mg.kg-1.h-1 i.v.), nitrous oxide (70%) and pancuronium (0.30 mg.kg-1.h-1 i.v.) on these variables was studied in eight normoventilated pigs. CBF was reliably assessable at 10-min intervals by clearance of intra-arterially injected 133Xe, monitored by an extracranial scintillation detector. CMRO2 was calculated from CBF and the simultaneously measured cerebral arteriovenous difference in blood oxygen content. The intracerebral distribution of a contrast medium injected into the external and internal carotid arteries was studied by angiography, and the cerebral venous outflow was investigated by measurements of the distribution of an intra-arterially administered non-diffusible tracer, [99mTc]pertechnetate, to the internal and external jugular veins. After a 3-h equilibration period, CBF and CMRO2 were determined on six occasions over a study period lasting 1 h 40 min. The mean ranges of these variables were 56-60 and 1.9-2.0 ml.100 g-1.min-1, respectively. We conclude that the model enables repeated assessments of CBF and CMRO2 under stable physiological background conditions and thus valid cerebral pharmacodynamic investigations of drugs given for anaesthesia.     

The effect of 2,4-diamino-6-hydroxy-pyrimidine on postburn Staphylococcus aureus sepsis in rats

GTP-cyclohydrolase I (GTP-CHI) is the first and rate-limiting enzyme for the de novo biosynthesis of biopterin. The present study was to observe the effect of 2,4-diamino-6-hydroxy-pyrimidine (DAHP),an inhibtor of GTP-CHI, on the development of postburn Staphylococcus aureus sepsis. Methods: 56 male Wistar rats were randomly divided into four groups as follows: normal control group (n= 10), scald control group(n= 10),pos tburn sepsis group (n= 20) and DA HP treatment group (n= 16). In the scald control group, rats were subjected to a 20% total body surface area (TBSA) Ⅲ° scald injury, then sacrificed at 24 hrs. In the postburn sepsis group (n=20), rats were inflicted with 20% TBSA Ⅲ° scald followed by Staphylococcus aureus challenge, and they were further divided into 2 and 6 hrs groups. In the DAHP treatment group (n= 16), animals were intraperitoneally injected with a dose of 1g/kg DAHP prior to Staphylococcus aureus challenge, and then further divided into 2, 6 hrs groups. Tissue samples from liver, kidneys, lungs and heart were collected to determine GTP-CHI, inducible nitric oxide synthase (iNOS) and tumor necrosis factor-α (TNF-α) mRNA expression. Meanwhile, biopterin and nitric oxide (NO) levels in these tissues were also measured. Results: After the scald injury followed by Staphylococcus aureus challenge, GTP-CHI mRNA expression and biopterin levels significantly elevated in various tissues such as liver, heart, kidneys and lungs, so did the values of iNOS mRNA expression and NO formation (P＜0.01). Pretreatment with DAHP could significantly reduce GTP-CHI/biopterin induction (P＜0. 05～0. 01), and the up-regulation of iNOS/NO was also suppressed. Furthermore, DAHP administration could also inhibit the gene expression of TNF-α. 2 hrs after septic challenge, TNF-α mRNA expression in liver, kidneys and lungs in DAHP-treated group were 35.7%, 37.3% and 33.0% of those in postburn septic group, respectively. Additionally, in animals without DAHP treatment, the 6-hour mortality was 55.6% (20/36), while it was only 25.0% in DAHP-treated animals (4/16, P=0. 08). Conclusions: Early treatment with DAHP might be a potential strategy to prevent the development of postburn Staphylococcal sepsis, which appears to be associated with down-regulation of biopterin and NO formation by DAHP.     

变应性鼻炎患者血清一氧化氮水平变化及临床意义

目的 :通过 5 6例变应性鼻炎患者血清一氧化氮 (NO)浓度的观察 ,研究内源性NO水平的变化与变应性鼻炎病理过程的关系及其临床意义。方法 :血清NO水平采用硝酸还原酶比色法测定。结果 :变应性鼻炎组血清NO水平显著高于正常对照组 (q =2 7.2 3,P <0 .0 1)及慢性鼻炎组 (q =15 .2 3,P<0 .0 1)。慢性鼻炎组与正常对照组血清NO浓度差异无显著性 (q =1.89,P >0 .0 5 )。结论 :变应性鼻炎患者血清中NO水平显著高于正常对照组及慢性鼻炎组 ,提示NO在变应性鼻炎的发病过程中可能起重要作用 ,对其机理的研究为变应性鼻炎的治疗提供新的方法。     

实验性减压病兔血清NO和SOD的含量变化及其意义

目的　探讨一氧化氮 (NO)和超氧化物歧化酶 (SOD)含量在减压病发病过程中的变化及其在发病机制中的意义。方法　将 16只实验兔放入加压舱中 ,于 5 min内用压缩空气加压至 0 .5 MPa,停留 6 0 min,然后于 5 m in内再减至常压。分别于进舱前、出舱后即刻和出舱后 2 4 h,应用心内穿刺方法采血 2 m l,分离血清 ,避免溶血。应用硝酸还原法和改良亚硝酸法分别及时测定血清 NO含量和 SOD活性。结果　 (1)血清中 NO含量在减压出舱后即刻 [(112 .73± 15 .74 ) μm ol/ L]及出舱后 2 4 h[(117.6 0±16 .0 7) μm ol/ L],与进舱前自身对照 [(85 .33± 12 .6 8) μmol/ L]比较 ,明显增高 (P<0 .0 1)。 (2 )血清中SOD活性在出舱后即刻 [(6 5 .97± 16 .5 2 ) NU/ ml]与出舱后 2 4 h[(6 3.0 1± 16 .10 ) NU/ m l],与进舱前[(85 .84± 16 .6 8) NU/ ml]比较 ,均明显降低 (P<0 .0 5 )。结论　 NO含量的增加和 SOD活性的降低可导致自由基生成增加 ,这可能在减压病的继发性损伤中起着重要作用。     

乙醇毒染大鼠睾丸总抗氧化能力、一氧化氮和一氧化氮合酶的变化与生殖细胞凋亡的关系

目的:探讨饮酒大鼠睾丸总抗氧化能力(T-AOC)、一氧化氮(NO)含量和一氧化氮合酶(NOS)活性的变化与生殖细胞凋亡的关系。方法:20只成年健康SD雄性大鼠随机均分为对照组和实验组,实验组和对照组分别用50%的乙醇溶液和蒸馏水按10 m l/kg每晚灌胃1次连续26 d(两个生精周期)后,用硝酸还原酶法测定睾丸组织中NO含量;用化学比色法测定其T-AOC和NOS活性;原位缺口末端标记(TUNEL)法检测生殖细胞凋亡指数(AI)的变化。结果:与对照组相比,实验组生殖细胞AI增加(P<0.01);睾丸组织T-AOC极显著下降(P<0.01),而NO含量明显上升(P<0.01)、NOS活性显著增强(P<0.01)。结论:大量饮酒能诱导生殖细胞凋亡增加,NOS活性增强导致NO的过量产生及T-AOC的显著下降是其重要原因。     

S-nitrosoglutathione-containing hydrogel accelerates rat cutaneous wound repair

BACKGROUND: Nitric oxide (NO) plays a key role in wound repair and S-nitrosothiols like S-nitrosoglutathione (GSNO) are well known NO donors. METHODS: Animals were separated in two groups and submitted to excisional wounds on the dorsal surface at the first day. GSNO (100 microm)-containing hydrogels were topically applied on the wound bed in the GSNO group, daily, during the first 4 days. Control group was topically treated with hydrogel without GSNO for the same period. Wound contraction and re-epithelialization were measured. Animals were sacrificed 21 days after wounding. Samples of lesion and normal tissue were formalin-fixed, paraffin embedded for histological analysis. RESULTS: Wound contraction, measured 14 and 21 days after wounding, was greater in the GSNO group than in the control group (P<0.05 for both). The re-epithelialized wound area, measured 14 days after wounding, was higher in the GSNO group than in the control group (P<0.05). A higher amount of inflammatory cells was observed in superficial and deep areas of the granulation tissue of the control group compared to the GSNO group. Twenty-one days after wounding, thin red-yellow collagen fibers arranged perpendicularly to the surface were found in the granulation tissue of the control group, whereas in the GSNO-treated group collagen fibers were thicker and arranged parallel to the surface. Increased number of mast cells was observed in the GSNO group compared with that in the control group. Vascularization and myofibroblast distribution were similar in both groups. CONCLUSION: Topical application of GSNO-containing hydrogel during the early phases of rat cutaneous wound repair accelerates wound closure and re-epithelialization and affects granulation tissue organization.     

尼莫地平对阿尔茨海默病大鼠脑组织NO、NOS含量及行为学的影响

目的：探讨尼莫地平对阿尔茨海默病（AD）大鼠脑组织一氧化氮(NO)、一氧化氮合酶（NOS）浓度及行为学改变的影响。方法：SD大鼠30只，随机分为空白对照组,AD模型组和尼莫地平组，采用大鼠脑组织立体定位微量注射技术，尼莫地平组和AD模型组用鹅膏蕈氨酸（IBO）1μl(5μg)损毁大鼠双侧迈内特基底核（nbM）建立AD动物模型，空白对照组以0.1mol/L pH7.4PB液代替IBO。尼莫地平组给予尼莫地平0.5mg/kg，空白对照组和AD模型组以生理盐水代替尼莫地平，连续灌胃60d，每d2次，每次2ml。做迷宫试验及跳台试验测学习记忆能力，然后将大鼠断头处死，分离海马及大脑皮质，分别检测NO,NOS含量。结果：AD模型组较空白对照组学习记忆能力显著降低，海马及大脑皮质NO,NOS含量显著升高，尼莫地平较AD模型组学习记忆能力显著升高，海马及大脑皮质NO、NOS含量显著降低。结论：用IBO损毁大鼠双侧nbM可建立AD动物模型，尼莫地平可显著改变AD模型大鼠的学习记忆能力，降低海马及大脑皮质NO、NOS含量。     

一氧化氮及一氧化氮合酶在遗传性癫痫易感大鼠惊厥发作中的作用

目的：探讨一氧化氮、一氧化氮合酶在遗传癫痫易感大鼠惊厥发作中的变化及作用。方法：选择惊厥评分在30－40的P77PMC大鼠35只，均分A－G7组，A组为对照组、G组预先30min腹腔注射一氧化氮合酶抑制剂L－NAME，分别于铃声刺激致惊后0．5、1、2、4,12h断头处死，取出脑组织分离双侧大脑皮层、海马等组织匀浆，测定一氧化氮及一氧化氮合酶，分别统计并进行t检验。结果：惊厥后0．5－1h皮层、海马一氧化氮、一氧化氮合酶逐渐升高，2h达峰值，4－12h恢复正常，应用L－NAME后，一氧化氮、一氧化氮合酶升高被抑制，但大鼠惊厥评分增高并致1例惊厥后死亡和明显延长惊厥持续时间。结论：惊厥后大鼠体内一氧化氮、一氧化氮合酶合成增加，给予合成酶抑制后能明显下降，但能加重惊厥程度和延长持续时间，提示一氧化氮于惊厥后升高，可能作为内源性抑制性性质，在惊厥发作自行终止机制中具有重要作用。