Evidence for lipid peroxidation by paraquat in the perfused rat lung

In order to evaluate the effect of paraquat on oxidative radical reactions in the lung, we studied MDA production and chemiluminescence (spontaneous and tBuOOH-induced) in the isolated rat lung. After 2 hr of perfusion with 3.0 mM paraquat, MDA content in lung homogenates was 16 +/- 7 nmol/gm dry weight higher than in control lungs (mean +/- S.E., n = 7, p less than 0.05 by paired test); during 30 min of perfusion, malondialdehyde efflux was 33 +/- 15 nmol/gm dry weight higher than in control perfusates (n = 6, p less than 0.05). Spontaneous chemiluminescence was not augmented by 2 hr of perfusion with concentrations of paraquat ranging from 0.75 to 6.0 mM. On the other hand, tBuOOH-induced chemiluminescence was 17% +/- 3 higher immediately after the addition of hydroperoxide and reached a 16% +/- 6 higher plateau for the paraquat-perfused lungs than for control lungs (n = 10, p less than 0.05). Spectral analysis of the light emitted during induced chemiluminescence demonstrated peak intensity between 630 and 730 nm for both control and paraquat-treated lungs. Increased MDA production and increased induced chemiluminescence indicate that perfusion with paraquat enhances lipid peroxidation in the isolated rat lung.     

Organ chemiluminescence: noninvasive assay for oxidative radical reactions.

In situ and perfused rat livers showed a spontaneous chemiluminescence of 7-12 counts/sec . cm2 (corresponding to 7-12 x 10(3) photons/sec . cm2); chemiluminescence was increased up to 30 times by infusion of exogenous hydroperoxides. The chemiluminescence of the perfused liver was oxygen dependent. Ethyl, t-butyl, and cumene hydroperoxides were almost equally effective in inducing light emission in the perfused liver. Glutathione release and chemiluminescence showed a parallel increase upon hydroperoxide supply to the perfused liver. A partial spectral analysis of the chemiluminescence of the perfused liver showed a predominance of red-light-emitting species, presumably arising from the singlet oxygen dimol-emission peaks. Many side reactions derived from the complex free radical sequence of lipid peroxidation could afford the chemistry leading to light emission, which represents only about 10(-14) of the utilization of peroxide.     

Team-based simulations for new surgeons: Does early and often make a difference?

Background

Current work hour restrictions and the expansion of requirements for surgery residents has led to decreased time on high-acuity rotations such as trauma and acute care surgery. In an effort to improve resident competency, we examined the efficacy of a new team-based trauma curriculum for postgraduate year 1 (PGY1) residents.

An intragenic deletion of the factor IX gene in a family with hemophilia B.

A family of seven patients severely afflicted with hemophilia B has been studied for their factor IX genes through the use of factor IX cDNA and genomic DNA probes. The patients had detectable (less than 10% of normal) factor IX antigen in urine and no detectable inhibitors in sera to factor IX protein. Based on the DNA hybridization analysis, these patients showed a partial intragenic deletion in their factor IX gene. The deletion included two exons (exons V and VI) coding for the amino acid sequence from number 85 to 195 of the factor IX protein. The deleted portion of the gene contained the entire factor IX activation peptide. The length of the deletion was estimated to be 10 +/- 0.3 kilobase pairs. This specific gene has been named FIXSeattle. In this family both the deletion and a Taq 1 restriction fragment length polymorphism can be used as a useful marker for accurate detection of female carriers of the deficient factor IX gene.     

Blood transfusion exposure does not influence survival in patients with carcinoma of the breast

There is abundant evidence of immune modulation induced by exposure to blood transfusions. Some studies have demonstrated a detrimental effect of transfusion on the recurrence of malignant disease and survival. We retrospectively studied the impact of blood transfusion exposure on 229 patients with breast cancer who were seen from July 1973 to September 1980, had at least 5 years' follow-up and had been randomized by therapy at the time of diagnosis. The patients were divided into four groups according to transfusion history: Group 1 (111 patients), no transfusion; Group 2 (34 patients), first transfusion after mastectomy; Group 3 (41 patients), first transfusion at mastectomy; and Group 4 (43 patients), first transfusion before mastectomy. All transfused patients received red cells or whole blood or both. At the time of analysis, 124 (54%) of the patients had died. Only Group 2 was statistically associated with decreased survival; recurrence of disease was 85 percent in this group, compared with 53 percent to 61 percent in the other three groups (p = 0.006, log-rank test). In general, Group 2 patients received transfusions because of recurrent disease. We conclude that transfusions before or at mastectomy are not associated with increased recurrence or reduced survival in patients with breast cancer.     

颈动脉内中膜厚度与初诊2型糖尿病视网膜病变的关系

目的:研究发现,糖尿病视网膜病变和动脉粥样硬化终点事件相关。试验拟验证颈动脉内中膜厚度与初诊汉族2型糖尿病患者糖尿病视网膜病变相关危险因素的关系。方法:①试验对象:选择2006-06/2007-06本院住院的初诊2型糖尿病患者187例,男114例,女73例;平均年龄(51±14)岁;平均体质量指数(24.7±4.7)kg/m2。均符合1997年美国糖尿病协会的2型糖尿病诊断标准,排除既往已存在心血管疾病者。患者对治疗及试验均知情同意。根据眼底照相检查结果,将所有受检者分为糖尿病视网膜病变组及非糖尿病视网膜病变组进行统计分析。②试验方法及评估:所有患者询问一般情况,测量颈动脉内中膜厚度以及相关生化指标,对糖尿病视网膜病变相关因素进行单因素及多因素Logistic回归分析。结果:纳入2型糖尿病患者187例,均进入结果分析。单因素Logistic回归分析显示,高血压、糖尿病家族史、颈动脉内中膜厚度、尿白蛋白、低密度脂蛋白胆固醇与糖尿病视网膜病变发生呈显著正相关,多因素Logistic回归分析未见显效因素。结论:单因素回归分析中颈动脉内中膜厚度及其他4项指标与糖尿病视网膜病变相关,而多因素回归分析这些因素未进入主效基因模型。     

Critical need for pharmacologic treatment options in NAFLD: A pediatric perspective

Nonalcoholic fatty liver disease (NAFLD) affects up to 70% of children with obesity and has become the number one etiology for liver transplant in the United States. Early, effective intervention is critical to prevent disease progression into adulthood. Yet, it is seldom achieved through lifestyle modification alone. Thus, children must be included in NAFLD pharmacology trials, which, to date, continue to focus primarily on adult populations. This commentary serves as a call to action.

Three hundred forty million children worldwide are affected by overweight/obesity (https://www.who.int/end‐childhood‐obesity/publications/taking‐action‐childhood‐obesity‐report/en/). Without intervention, > 75% of these children will continue to gain excessive weight and become adults with obesity. ¹ Alarmingly, almost all adults with obesity (90%) develop comorbid nonalcoholic fatty liver disease (NAFLD), the leading etiology for liver transplant in the United States. ² Thus, effective, early life intervention is critical for children with obesity, up to 70% of whom already have comorbid NALFD by adolescence. ² Lifestyle modifications (e.g., diet and exercise) resulting in weight loss of as little as one kilogram can improve NAFLD in children. ³ However, overall adherence to lifestyle modification is low, with the exception of a few pediatric research studies that offer intense follow‐up ³ , ⁴ or comprehensive in‐home services. ⁴ As such, bariatric surgery is increasingly recognized as an option for weight reduction in children, but it is invasive and there is an unpredictable subset of patients who experience worsening liver fibrosis and NAFLD progression postsurgery. ⁵ This leaves a critical, unmet need for effective pharmacologic interventions in pediatric NAFLD.Currently, there are no approved medications for NAFLD; however, the landscape of potential therapeutic agents is evolving rapidly and showing promise, as highlighted in a comprehensive review by Attia et al. published in Clinical and Translational Science. ⁶ In addition to the many novel therapeutic agents discussed (e.g., obeticholic acid, fibroblast growth factor 19 and 21 analogues, thyroid hormone receptor‐β agonists, etc.), the authors briefly mention past therapeutic experiences with medications already on the market for other clinical indications. Although the adult experience with some of these medications was equivocal, it is important to note that some agents show promise for repurposing in pediatric NAFLD.One example is metformin, a drug already approved for the treatment of type 2 diabetes in children > 10 years of age. In a study of lifestyle modifications combined with either metformin or placebo in children with obesity and insulin resistance ± NAFLD, the metformin group demonstrated a significant decrease in NAFLD scores and NAFLD prevalence, whereas the placebo group experienced an increase from baseline for both. ⁷ Interestingly, when metformin was administered at lower doses in other pediatric trials, it demonstrated isolated improvement in histopathology features (e.g., hepatic ballooning), ⁸ but not in the overall histopathology NAFLD score, suggesting that metformin’s effect on NAFLD may be dose dependent. Therefore, further studies of metformin in the setting of pediatric NAFLD are indicated.Other drugs already approved for obesity‐related comorbidities may also be of interest for repurposing in pediatric NAFLD. Statins, cholesterol‐lowering agents prescribed to patients with obesity and hypercholesterolemia, have been shown to significantly improve hepatic function in patients with obesity and NAFLD ⁹ —presumably through anti‐inflammatory mechanisms in the liver. Although no data are available in pediatrics, in adults with NAFLD, statin therapy is well‐tolerated, with low frequency of hepatotoxicity similar to placebo, ⁹ making statins intriguing drug candidates to consider for the treatment of pediatric NAFLD. Secondary analyses of off‐target treatment effects of medications already prescribed to children with obesity (e.g., statins and metformin) may be helpful in uncovering important insights into therapeutic options for pediatric NAFLD treatment. Especially while best practices for expanding novel NAFLD therapeutics trials to pediatrics remain under development, as referenced in a recent draft guidance from the US Food and Drug Administration (https://www.fda.gov/media/119044/download).In our opinion, and the opinion of other experts, ¹⁰ inclusion of pediatric populations in adult NAFLD pharmacology trials is important and represents a strategy that has been successfully implemented in oncology trials. Yet, the majority of new NAFLD agents continue to be pursued more aggressively for adults than children. As illustrated in the review by Attia et al., ⁶ only 2 of the 17 therapeutic trials discussed included children. By excluding children, we are missing a critical opportunity for early intervention to prevent NAFLD progression from simple hepatic steatosis to more advanced disease (i.e., steatohepatitis, fibrosis, cirrhosis, hepatocellular carcinoma, and end‐stage liver failure). Our hope is that increased awareness of pediatric NAFLD prevalence, coupled with the National Institutes of Health policy for inclusion of research subjects across the lifespan (https://grants.nih.gov/policy/inclusion/lifespan.html), will encourage investigators to include pediatric patients in clinical trials of NAFLD therapeutics.Inclusion of children in pharmacology trials comes with its own set of unique challenges and nuances (e.g., ontogeny, age‐appropriate outcome measures, parental informed consent and informed assent of minors, etc.), beyond the scope of this commentary and as comprehensively reviewed in a pediatric tutorial guide by Shakhnovich et al. ¹¹ In addition, to facilitate inclusion of children specifically in pharmacology trials for NAFLD, NAFLD‐specific noninvasive biomarkers are urgently needed. The majority of studies reviewed by Attia et al. ⁶ relied on histopathology‐based assessment of NAFLD as a therapeutic outcome measure. However, liver biopsy is invasive and histopathology assessment is not always feasible or ethical in children, especially in the context of research. Alanine aminotransferase, the most commonly utilized clinical serum biomarker of liver injury is nonspecific for NAFLD. Therefore, several more‐specific biomarkers are currently under investigation; among them, serum bile acids. Total fasting and postprandial bile acids, and the ratios of conjugated and secondary bile acids, are consistently higher in the sera of adults with nonalcoholic hepatic steatosis, compared with healthy controls. ¹² Pediatric studies of bile acids lag behind, are sparse and inconsistent, and are needed to establish minimally invasive biomarkers of NAFLD for children.Recently, noninvasive liver imaging biomarkers have become more widely available, and it is encouraging to see these modalities incorporated into NAFLD therapeutics research, including four trials discussed by Attia et al. ⁶ Both ultrasound elastography and magnetic resonance elastography can quantify liver stiffness as a noninvasive surrogate for liver fibrosis. However, NAFLD presents a challenge to both techniques because elastography values are affected by both fat and fibrosis. Magnetic resonance proton density fat fraction (MR‐PDFF) can directly estimate hepatic fat content and allows clinicians and researchers to separate the individual contributions from fat vs. fibrosis to liver stiffness. However, MR‐PDFF is only available in specialized tertiary care centers and is expensive. Ultrasound techniques for fat quantification could offer a cheaper, more readily available alternative to MR‐PDFF and these techniques are likely to become widely available in the near future.Thus, the landscape of therapeutic pharmacology trials for NAFLD is rapidly evolving. The advent of noninvasive biomarkers for monitoring NAFLD treatment response offers promise and opportunity, especially for inclusion of pediatric patients in research. A concerted effort must be made to include children in NAFLD pharmacology trials, as NAFLD affects up to 70% of children with obesity, ² and early childhood intervention is key to minimize/reverse disease progression to end‐stage liver disease in adulthood.     

颈椎椎后肌肉组织中肌膜Na^＋-K^＋-ATP酶活性与颈椎病

目的:探讨颈椎椎后肌肉组织Na -K -ATP酶活性变化与颈椎病的关系。资料来源:应用计算机检索PubMed1988-01/2004-12相关骨骼肌损伤与肌组织Na -K -ATP酶关系的文献,检索词“Na -K pump,Na -K -ATPase,muscle”,限定文献语言种类为English。同时计算机检索CNKI1990-01/2005-12相关Na -K -ATP酶与骨骼肌损伤的关系及颈椎病发病病因的文献,检索词“Na -K -ATP酶,骨骼肌,颈椎病病因”,限定文献语言种类为中文。资料选择:对资料进行初审,选取包括Na -K -ATP酶与肌组织损伤关系的文献,开始查找全文。纳入标准:Na -K -ATP酶活性变化与骨骼肌损伤密切相关的文献研究。排除标准:重复研究,Meta分析类文章。资料提炼:共检索到939篇关于Na -K -ATP酶与骨骼肌损伤相关方面的文献,最终纳入20篇符合标准的文献。资料综合:众多研究表明,Na 、K 与骨骼肌的兴奋、收缩、疲劳有密切关系,而Na -K -ATP酶又是调节细胞内外Na 、K 浓度必不可少的高分子蛋白,也就是说,骨骼肌一系列活动均离不开Na -K -ATP酶,Na -K -ATP酶活性变化与骨骼肌损伤是相互影响的。而强迫屈颈体位作为颈椎病发病的危险因素之一,可使颈椎椎后肌肉Na -K -ATP酶活性降低,酶活性降低致使肌细胞损伤,并最终导致骨骼肌损伤而发病。结论:以颈椎椎后肌肉酶活性的变化来阐释中医药对颈椎病确切疗效的相关研究未见,这有待于进一步研究,以充分展示中医药在颈椎病等相关疾病中的治疗优势。     

肿瘤干细胞的研究与进展

目的:作为"种子细胞"的肿瘤干细胞对研究肿瘤发生及其临床治疗具有重要意义。总结近年来肿瘤干细胞的研究进展,对肿瘤干细胞的概念、特性及应用进行综述。资料来源:应用计算机检索Medline数据库1980-01/2006-12期间的相关文章,检索词为"cancer stem cells",限定文章语言种类为English。资料选择:对资料进行初审,并查看每篇文献后的引文。纳入标准:肿瘤干细胞的研究进展及临床价值。排除标准:重复研究。资料提炼:共收集到106篇相关文献,30篇文献符合纳入标准,排除的76篇文献为内容陈旧或重复。符合纳入标准的30篇文献中,分别涉及肿瘤干细胞的定义及来源、研究进展、临床治疗价值等内容。资料综合:肿瘤干细胞具有分裂增殖、自我更新以及分化成其他细胞的能力,目前已证实其存在于白血病、乳腺癌、脑癌、前列腺肿瘤等肿瘤组织中。目前的抗肿瘤治疗方法主要针对的是大多数已经分化的肿瘤细胞,而不能影响到肿瘤干细胞,即治标不治本。肿瘤的复发、转移以及耐药等特征都很可能与肿瘤干细胞有关,因此肿瘤治疗的关键应是针对肿瘤干细胞进行灭杀,又要保护正常干细胞,但此两种细胞表型极为相似,故应找到更为特异的靶点。结论:肿瘤干细胞不仅已经从血液系统的恶性肿瘤中成功分离出来,在大量实体瘤中也证实了肿瘤干细胞的存在,其耐药机制之一是表达一种或多种药物运载蛋白,对于肿瘤的发生及治疗提供了更多的思路和方向。