Magnesium inhibits the hypertensive but not the cardiotonic actions of low-dose epinephrine

Intravenous magnesium supplementation is often used to control cardiac arrhythmias and coronary artery vasospasm resulting from disturbances of magnesium homeostasis after coronary artery bypass surgery. Many such patients also require inotropic drug support of depressed myocardial function. However, increased serum magnesium concentrations directly depress cardiac contractility in animals and may interfere with catecholamine actions. To determine whether small intravenous doses of magnesium sulfate (MgSO4) interfere with the cardiotonic actions of epinephrine, we examined the hemodynamic effects of MgSO4 and epinephrine infusion in 17 cardiac surgical patients on their 1st postoperative day in a prospective, controlled study. In 11 patients, infusion of MgSO4 (7-mg.kg-1 bolus followed by 10 mg.kg-1.h-1 as a continuous infusion) increased serum magnesium concentrations by 44% (mean +/- standard error of the mean [SEM] of 0.8 +/- 0.1 to 1.2 +/- 0.1 mM; P less than 0.01) but had no significant effect on heart rate; mean arterial, central venous, or pulmonary arterial occlusion pressures; or cardiac output. Epinephrine infusion (30 ng.kg-1.min-1) significantly increased cardiac index (2.7 +/- 0.1 to 3.1 +/- 0.21.min-1.m-2; P less than 0.05); this effect was not altered by MgSO4 administration (n = 11). However, MgSO4 significantly blunted epinephrine's hypertensive action and prevented a significant increase in mean arterial pressure during concurrent MgSO4-epinephrine administration. Six placebo control patients were given two sequential infusions of epinephrine separated by a placebo infusion to rule out an effect of time on the hemodynamic response to epinephrine. Mean arterial pressure and cardiac index responses to epinephrine were identical before and after placebo infusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

兔眼视网膜厚度的光学相干断层扫描测量与组织学检查的相关性研究

目的 探讨兔眼视网膜厚度的光学相干断层扫描(optical coherence tomography,OCT)检测与组织学检查结果的相关性。 方法 采用OCT对16只兔眼视网膜进行扫描,然后对相应部位的视网膜作组织切片检查。OCT成像截面采用人工辅助(需要检查者对反射界面进行人工定位)和电脑自动测量两种方法进行分析。 结果 两种OCT检查法测得的视网膜厚度与组织学检查结果有良 好的相关性。OCT人工辅助检查法(γ＝0.84,P＜0.001)较电脑自动测量方法(γ＝0.66,P＜0.01)的相关性略好。前者测量的误差范围( 95%可信限)较小,在－2．99～5.13μm之间,而后者则高达11.09μm。 结论 OCT能准确定量检测兔眼视网膜厚度;部分OCT成像截面可能因电脑机械测量而产生误差,通过人眼识别给予矫正后能提高检查的准确性。 （中华眼底病杂志,2000,16：71-138）     

要使查寻科技期刊论文方便快捷I.应考虑的诸方面

只有查寻到论文出处,才能见到论文,然而,期刊中的论文查寻常因作者提供的资料含糊不全或编辑和出版者提供的信息不够充分而遇到困难。因此,编辑和出版者有必要为他们期刊中的论文查寻提供方便——他们应遵循某些基本规则。这些规则主要与一种期刊作为一个整体的外观、一期期刊的外观以及每篇论文特别是论文首页的外观有关。对于应考虑的最重要的诸方面都作了阐述。     

21世纪的编辑人才素质与培养

21世纪科技期刊编辑工作具有新的特点,而读者的心理与行为也将有巨大的变化,对编辑人才素质提出了更高的要求,探讨编辑人才的培养是当前编辑出版界关注的热点。创设优良的成长环境,让编辑学会扮演好自己的角色,建立起适宜的“压任务”和“担担子”的激励机制,培养出合格的编辑人才,才能适应21世纪对编辑工作的需要。     

科技编辑突出重点方法初探

对科技编辑突出重点方法的内容、方法论意义、理论依据及其在编辑活动的实际应用进行初步探讨。科技编辑突出重点方法渗透于从选题、组稿、审读、加工、出版、发行到经营管理的各个环节,将其合理应用,对于提高编辑工作效率是十分有益的。     

科技期刊插图形态结构及布局的审美分析

准确、精美的插图不仅能起到活跃和美化版面的作用,还可以引发读者的阅读审美兴趣,从而使科技期刊真正能发挥它的科学指导作用。本文通过对科技期刊插图的审美分析,认为插图的形态结构及平面布局是影响其审美效果的关键。     

Effect of chain length on absorption of biologically active peptides from the gastrointestinal tract.

OBJECTIVES: Protein digestion generates many peptides in the gut lumen. Some of these peptides possess biological effects when tested using in vitro systems. It is clear that dipeptides and tripeptides can be absorbed intact from the gastrointestinal tract. However, the fate of larger peptides and small proteins remains unclear. Equally unclear are the biologic potencies of absorbed peptides and the quantity of peptide that must be administered into the gut to produce a biologic effect. Thus, the purpose of this study was to determine the effect of amino acid chain length on the ability of enterally administered peptides to produce biologic effects. METHODS: Small bowel feeding tubes, jugular catheters, and arterial lines were placed into adult male Sprague-Dawley rats. Rats were administered intravenous (50 microg) and enteral (125 and 500 microg) thyrotropin-releasing hormone (TRH, a tripeptide), intravenous (100 microg) and enteral (100 and 500 microg) luteinizing hormone-releasing hormone (LHRH, a decapeptide), and intravenous (0.5 mg) and enteral (0.5 and 25 mg) insulin (a 51-amino acid polypeptide). The quantity of peptide administered represented less than 0.5% of a rat's normal daily protein intake. The biologic effect of TRH, LHRH, and insulin were assessed using thyroid-stimulating hormone (TSH) response, follicle-stimulating hormone (FSH) response, and glucose. We also measured serum levels of insulin in the rats following enteral insulin administration. RESULTS: The results indicate that enteral TRH (125 and 500 microg) produced the same TSH response as intravenous TRH. The response to 500 microg enteral LHRH was 50% of the response to intravenous LHRH and the response to 25 mg enteral insulin was 30% of the response to 0.5 mg intravenous insulin. Serum insulin levels increased significantly following both 0.5 and 25 mg enteral insulin. CONCLUSIONS: These results support the concept that small (di- and tripeptides) and large (10-51 amino acids) peptides generated in the diet can be absorbed intact through the intestines and produce biologic effects at the tissue level. The potency of the enterally administered peptides decreases as the chain length increases. We postulate that absorbed dietary peptides play a role in the modulation of organ function and disease progression.     

透明细胞性肾细胞癌在不同组织学分类中的比较研究

比较2004年WHO肾细胞癌组织学分类标准与1997年WHO及更早的分类标准的异同,总结常见的诊断差异及可能原因,纠正及更新对肾细胞癌的传统病理分类的观念。方法:收集天津医科大学肿瘤医院2004年2月至2008年2月间,根治性肾切除术后病理诊断为透明性肾细胞癌249例,按2004年WHO肾癌组织学分类标准重新分类,并收集相关临床资料进行分析。结果:原分类法的249例透明细胞癌,经重新分类后,发现透明细胞癌176例,乳头状肾细胞癌42例,嫌色细胞癌5例,多房性囊性肾细胞癌3例,混合型肾细胞癌23例（透明细胞癌+乳头状肾细胞癌21例,乳头状肾细胞癌+嫌色性肾细胞癌2例）。结论:部分乳头状肾细胞癌与嫌色肾细胞癌过去易被诊断为透明细胞癌,两者具有相似的胞浆特点,及对其组织学特点认识不清是其主要原因;中国人乳头状肾细胞癌的发病率与国外相近,且其亚型的分类及诊断有待进一步的研究。      

药物对TNF诱导的牛脑微血管平滑肌细胞增值的拮抗作用

研究表明,肿瘤坏死因子(TNH)在50～5000U·mL^-1范围内呈剂量依赖性地诱导牛脑微血管平滑肌细胞增殖,TNF与该细胞培养24h时,即可明显刺激细胞增殖,48h时达最大刺激效应。欧芹素乙(imperatorin,Imp),异欧芹素乙(iso-imperatorin,Isi)在浓度为10^-6～10^-4mol·L^-1时,均可剂量依赖性地拮抗TNF诱导该细胞增殖。6-(α,α-二苯基乙酰哌嗪基苯基)-4,5-二氢-5-甲基-3(2H)哒嗪酮,6-(α-苯基乙酰哌嗪基苯基)-4,5-二氢-5-甲基-3(2H)哒嗪酮,则只在低浓度(10^-6mol·L^-1)时拮抗TNF诱导该细胞的增殖。     

Innate immunity of surfactant protein A and D in urinary tract infection with uropathogenic Escherichia coli

Objective To investigate the role of surfactant protein (SP) - A and SP - D in urinary tract infection mouse model, and evaluate the effects of SP-A and SP-D absence on urinary tract infection. Methods SP-A and SP-D double knockout (SP-A/D KO) mice were made. SP-A/D KO and wild-type (WT) C57BL/6 female mice were used for this study. The expression of SP-A and SP-D in kidney was detected by immunohistochemistry (IHC). The levels of p - p38 and p38 protein in kidneys were measured by Western blotting. Uropathogenic Escherichia coli or buffer was delivered into the bladder of female mice. At 24 and 48 h after inoculation, CFU of Escherichia coli in the kidney and urine of the treated and control mice were measured. Histological, cellular and molecular analysis were performed by several methods of H/E staining, IHC and Western blotting. The effects of SP-A and SP-D on bacterial growth were studied in vitro. Results SP-A and SP-D in kidney were located in the proximal tubules and collecting tubules. Compared with WT mice, infected SP - A/D KO mice with UPEC had higher CFU in kidneys and urine at 24 h and 48 h, increased inflammatory cells infiltration in kidneys（P＜0.05）. Compared with WT mice, SP - A/D KO mice had higher p38 MAPK phosphorylation levels in kidneys（P＜0.05）. Growth of Escherichia coli was greatly inhibited by both SP-A and SP-D（P＜0.05）. Conclusions Both SP-A and SP-D are expressed in kidney. SP-A and SP-D can attenuate UTI induced by UPEC which may be through inhibiting bacterial growth and modulating renal inflammation.