鼠膀胱肿瘤原位模型构建的机制研究

目的 探讨硝酸银、盐酸、胰酶和酒精预处理构建鼠膀胱肿瘤的成瘤机制。 方法 24G静脉留置针插入膀胱，PBS冲洗后，将小鼠随机分为5组，每组6只：（1）酒精作用组：22%酒精0.1ml保留20分钟；（2）胰酶作用组：0.2%胰酶保留30分钟；（3）酸碱作用组：0.1mmol/L HCl 0.1ml作用15秒后，PBS冲洗，0.1mmol/L NaOH 0.1ml作用5秒，排空膀胱；（4）硝酸银作用组：0.15mol/L硝酸银保留10秒；（5）对照组：0.1ml生理盐水。术后1和24小时随机处死每组3只小鼠，摘取膀胱，HE染色观察膀胱粘膜病理变化；戊二醛固定，电镜下观察膀胱粘膜细胞微结构变化；甲苯胺蓝染色，观察膀胱粘膜固有层肥大细胞数目变化；过碘酸-希夫(PAS)染色，观察膀胱粘膜GAG层变化。40只小鼠应用前四组预处理因素处理膀胱后，建立膀胱癌原位模型，计算各组成瘤率。 结果 胰酶和酒精处理1小时后，局部上皮伞状细胞脱落，粘膜下层暴露；酸碱和硝酸银处理组大部粘膜完整性破坏，粘膜下层暴露较多，连续性中断；对照组和实验组间炎症细胞浸润均不表现出统计学差异。24小时后，胰酶和酒精组可见局部轻度水肿并充血，粘膜完整性恢复较好，细胞间见紧密连接；而酸碱和硝酸银组上皮粘膜薄厚不均一，仍可见部分脱落粘膜。 结论 利用硝酸银和酸碱预处理膀胱可作为鼠膀胱肿瘤原位模型构建的首选方法。     

Clinical and laboratory features of patients with myophosphorylase deficiency (McArdle disease)

Mutations of PYGM, the gene encoding human myophosphorylase, produce a metabolic myopathy characterised by exercise intolerance and, in some patients, myoglobinuria. To illustrate the clinical and laboratory features of myophosphorylase deficiency, we describe 10 patients diagnosed in Auckland, New Zealand, between 1989 and 2009. We review the clinical, biochemical, and histologic features and the results of mutation analysis. All patients reported exercise intolerance since childhood or the teenage years, starting within minutes of moderate or intense exertion. The “second wind” phenomenon, or myoglobinuria, were each reported in about half the patients. The serum creatine kinase concentration was elevated in all patients where this had been measured. Muscle biopsies revealed subsarcolemmal vacuolation and histochemical absence of myophosphorylase. Analysis of PYGM showed mutations in all alleles, most commonly Arg49Ter or Gly204Ser. One patient harbored a novel mutation, Pro488Arg, predicted to seriously disrupt the tertiary structure of the enzyme. Myophosphorylase deficiency produces a fairly uniform set of symptoms, and consistent elevation of the serum creatine kinase concentration. The diagnosis can be confirmed in most patients by mutation analysis using a blood sample.     

Snake venom Lys49 myotoxins: From phospholipases A2 to non-enzymatic membrane disruptors

Snake venoms often contain toxins that cause a rapid necrosis of skeletal muscle fibers, referred to as myotoxins. The most common among them are phospholipases A₂ (PLA₂s), enzymes that have two independent evolutionary origins in snake venoms. Within the group II PLA₂s found in viperid venoms, a particular subgroup emerged, in which the otherwise conserved Asp49 of their catalytic center is replaced by Lys49. These intriguing proteins, referred to as Lys49 myotoxins, lost the ability to catalyze phospholipid hydrolysis, but still induce myonecrosis by a non-enzymatic mechanism based on membrane permeabilization as the critical event. Such mechanism is only partially understood. This review briefly describes the general structural and functional characteristics of the Lys49 myotoxins, and summarizes four proposed models of their functional “toxic site”. Finally, it discusses some novel insights into their mode of action, in particular examining arguments and experimental observations that could shed light on the possible nature of their membrane target on skeletal muscle cells, which remains elusive.     

Increase in plasma aldosterone during prolonged captopril treatment

Plasma aldosterone concentration was measured in seven patients before and during long-term angiotensin II suppression with captopril. Plasma aldosterone decreased initially from 62 to 9 pg/ml (p <0.01) after 1 month of captopril administration. Thereafter, it began to increase and after 1 year reached a level of 163 pg/ml, which significantly (p <0.01) exceeded the pretreatment value. During long-term captopril therapy, plasma renin activity remained elevated and plasma angiotensin II concentration suppressed. The mechanism responsible for the late increase in plasma aldosterone during long-term angiotensin II suppression with captopril remains to be elucidated. Body weight decreased initially, parallel to plasma aldosterone decrease, but after 6 months increased again to reach its pretreatment level after 1 year. Nevertheless a sizable and lasting hypotensive effect was observed in all patients.