Isolation and characterisation of a novel angiotensin I-converting enzyme (ACE) inhibitory peptide from the algae protein waste

A hendeca-peptide with angiotensin I-converting enzyme (ACE) inhibitory activity was isolated from the pepsin hydrolysate of algae protein waste, a mass-produced industrial by-product of an algae essence from microalgae, Chlorella vulgaris. Edman degradation revealed its amino acid sequence to be Val-Glu-Cys-Tyr-Gly-Pro-Asn-Arg-Pro-Gln-Phe. Inhibitory kinetics revealed a non-competitive binding mode with IC₅₀ value against ACE of 29.6 μM, suggesting a potent amount of ACE inhibitory activity compared with other peptides from the microalgae protein hydrolysates which have a reported range between 11.4 and 315.3 μM. In addition, the purified hendeca-peptide completely retained its ACE inhibitory activity at a pH range of 2–10, temperatures of 40–100 °C, as well as after treatments in vitro by a gastrointestinal enzyme, thus indicating its heat- and pH-stability. The combination of the biochemical properties of this isolated hendeca-peptide and a cheap algae protein resource make an attractive alternative for producing a high value product for blood pressure regulation as well as water and fluid balance.     

Hypotensive effect of a sweetpotato protein digest in spontaneously hypertensive rats and purification of angiotensin I-converting enzyme inhibitory peptides

We have investigated angiotensin I-converting enzyme (ACE) inhibitory activity in an enzyme digest of sweetpotato protein, the antihypertensive effect of the digest in spontaneously hypertensive rats (SHR), and the identification of an ACE inhibitory peptide. Protein was prepared from squeezed juice of sweetpotato by isoelectric focusing precipitation. Three kinds of proteases were selected for effective protein digestion. The digest, sweetpotato peptide (SPP), exhibited strong ACE inhibitory activity (IC₅₀: 18.2 μg/ml). SPP was orally administered by gavage to SHR at a dose of 100 mg/kg or 500 mg/kg. The systolic blood pressure and the diastolic blood pressure were measured at 0 (before administration), 2, 4, 8, and 24 h after administration. A dose-dependent decrease in systolic blood pressure in SHR was observed after oral administration of SPP. Significant differences between SPP-administered rats and control rats were observed 4 and 8 h after administration in the 500 mg/kg-administered group and 8 h after administration in the 100 mg/kg-administered group. Diastolic blood pressure also decreased in the SPP-administered groups, although the difference between SPP-administered rats and control rats was not significant. These results suggest that SPP may be useful in the prevention or treatment of hypertension. Peptides with ACE inhibitory activity were purified from SPP by absorption chromatography and preparative HPLC using an ODS column. The amino acid sequences of isolated peptides were I-T-P, I-I-P, G-Q-Y and S-T-Y-Q-T; their ACE inhibitory activities (IC₅₀) were 9.5 μM, 80.8 μM, 52.3 μM and 300.4 μM, respectively. In conclusion, I-T-P is a novel, strong ACE inhibitory peptide.     

Effect of dietary selenium on the progression of heart failure in the ageing spontaneously hypertensive rat

Oxidative stress has been directly implicated in hypertension and myocardial remodelling, two pathologies fundamental to the development of chronic heart failure. Selenium (Se) can act directly and indirectly as an antioxidant and a lowered Se status leads to a higher risk of cardiovascular disease. This study examined the role of Se on the development of hypertension and subsequent progression to chronic heart failure in spontaneously hypertensive rats (SHR). Three dietary groups were studied: (i) Se‐free; (ii) normal Se (50 μg Se/kg food); and (iii) high Se (1000 μg Se/kg food). Systolic blood pressure and echocardiography were used to detect cardiac changes in vivo. At study end, cardiac tissues were assayed for glutathione peroxidase activity, thioredoxin reductase activity, and protein carbonyls. The major finding of this study was the high heart failure‐related mortality rate in SHRs fed an Se‐free diet (70%). Normal and high levels of dietary Se resulted in higher survival rates of 78 and 100%, respectively. Furthermore, high dietary Se was clearly associated with lower levels of cardiac oxidative damage and increased antioxidant expression, as well as a reduction in disease severity and mortality in the SHR.     

睡眠呼吸暂停综合征合并高血压与胰岛素抵抗的研究

目的观察OSAS合并高血压患者体内炎症水平和胰岛素抵抗的关系。方法用PSG检查确诊重度OSAS患者70例,其中40例合并高血压病。用全自动生化仪检测血清真胰岛素(FINS)、C肽、C反应蛋白、空腹血糖,用稳态模型(HOMA)计算IR指数和胰岛β细胞功能指数。结果OSAS合并高血压患者血清CRP、FINS、血清C肽、HOMA-IR和HOMA-islet均较单纯OSAS患者明显升高。结论OSAS患者的慢性炎症通过形成胰岛素抵抗,在OSAS合并高血压的过程中可能起重要作用。     

高血压及药物治疗对飞行员认知功能的影响

目的探讨高血压及药物治疗对飞行员认知功能的影响。方法对13名无并发症的高血压飞行员和10名经降血压药物治疗后血压恢复正常的飞行员,进行闪光融合频率、多项反应时、空间位置记忆广度、注意力集中能力、警戒性等认知功能测试,并与年龄相近的13名健康飞行员对照。结果高血压组闪光融合频率、注意力集中能力、空间位置记忆广度分值均明显低于对照组（P〈0.05、P〈0.01和P〈0.01）,多项反应时中红、黄绿反应时间明显慢于对照组（P〈0.01）,警戒性作业总错误率明显高于对照组（P〈0.01）。高血压治疗组与高血压组均有统计学差异（P〈0.05、P〈0.01）。结论患高血压病飞行员有不同程度的认知功能减退,在飞行人员医学鉴定时应予重视。     

增益指数检测在高血压健康管理中的应用

目的研究桡动脉反射波增益指数（Augmentation Index,AI）水平与高血压患者心脏舒张功能、肾脏功能之间关系,探讨AI水平变化在高血压健康管理评价中的作用。方法对符合入选条件的105例高血压患者进行桡AI、proBNP水平测定、肾脏功能测定及超声心动图检查,并进行相关分析,绘制AI的受试者特征曲线并评价其在心脏舒张功能不全中的作用。结果proBNP水平升高组患者AI水平明显增加,而肾功能减退组患者AI水平相应增加,proBNP与AI正向相关,相关系数0．3697（P=0．003）。肌酐清除率与AI水平之间存在负相关,相关系数为-0．348（P〈0．05）。受试者工作特征曲线提示以AI诊断舒张功能不全的最佳临界值为85．5,该点灵敏度0．909,特异度0．889。结论桡动脉AI水平变化反映高血压患者心脏舒张功能状态的变化,亦能体现高血压肾脏功能状态的改变,可作为高血压健康管理的动态随访无创性指标.     

早期经鼻气管插管对高血压脑出血患者微创治疗后肺部感染的影响

目的研究早期经鼻气管插管对高血压脑出血患者微创治疗术后肺部感染发生率、ICU治疗时间的影响。方法选取58例2007年9月-2009年5月间于我院急诊科就诊并拟行微创治疗的高血压幕上型脑出血患者。根据GCS评分分层后进行随机分组,处理组于就诊时予以早期经鼻气管插管经人工鼻吸氧,对照组予以鼻导管或面罩吸氧,观察术后72h肺炎并发症发生率及ICU治疗时间,研究数据选取Fisher确切概率法及成组t检验方法进行统计分析。结果不管在GCS评分13～15分或6～12分的高血压脑出血患者中,早期插管组与对照组在术后肺炎发生率方面的差异无统计学意义(GCS13～15:21.4%vs35.7%,P=0.6776;GCS6～12:60%vs80%,P=0.2678),但在ICU治疗时间方面早期插管组较对照组明显缩短,两者间差异具有显著统计学意义(GCS13～15:4.9dvs6.9d;GCS6～12:8.2dvs10.3d,P<0.01)。结论对于高血压脑出血拟行微创治疗的患者行早期经鼻气管插管可明显减轻术后肺部并发症,减少ICU治疗时间,减轻患者经济负担,促进康复。     

乳果糖对门脉高压大鼠肠粘膜屏障功能保护作用的研究

目的探讨乳果糖对肝硬化门脉高压大鼠肠粘膜屏障功能的保护作用。方法50只雄性SD大鼠皮下注射50%CCl4橄榄油溶液,制造门脉高压模型。造模后存活大鼠随机分为:(1)治疗组;(2)对照组;(3)模型组。治疗组即乳果糖组,灌服乳果糖5mL/kg,每日2次,直至大鼠排稀便(共10d);对照组仅灌服葡萄糖水。11d后处死取全血及肝、脾、肾、和肠系膜淋巴结组织匀浆后作细菌培养,测细菌易位率;采用改良的偶氮基质显色法行内毒素测定;取回肠粘膜组织行HE、Masson染色和超微病理的观察研究;采用免疫组织化学方法测定回肠末端紧密连接蛋白(occludin)表达水平。结果治疗组细菌易位发生率较对照组和模型组均明显降低(P<0.05);与模型组、对照组比较,治疗组肝功能显著改善(P<0.01);治疗组血清内毒素水平(0.20±0.08)Eu/mL亦明显低于对照组、模型组之(0.33±0.06)Eu/mL、(0.44±0.07)Eu/mL(P<0.01);紧密连接蛋白的表达,治疗组与对照组、模型组比较,亦具有显著性差异(P<0.01)。结论口服乳果糖可以改善肠道屏障功能,减少门脉高压大鼠肠道菌群易位,减轻内毒素血症,从而一定程度上...     

肌肉介导心钠素基因对L-NNA高血压大鼠的作用

用重组人心钠素基因真核表达质粒ｐｃＤＮＡ３／ＡＮＦ，通过基因缝线转移至Ｌ－ＮＮＡ高血压大鼠股四头肌，发现可明显降低Ｌ－ＮＮＡ引起的高血压，并产生明显的利钠利尿作用。提示肌肉介导心钠素基因，作为一种ＤＮＡ药物治疗高血压，可能具有潜在应用价值。