血管紧张素转换酶2与心房颤动的关系

血管紧张素转换酶(ACE)2是肾素-血管紧张素系统的一个新成员,是迄今为止发现的第一个人类血管紧张素转换酶同族物。它可以水解血管紧张素Ⅱ(AngⅡ),生成血管紧张素(1-7),后者具有舒张血管和心脏保护功能。AngⅡ可促进心房颤动的发生和发展,ACE2则通过对AngⅡ的拮抗而在心房颤动过程中起到保护性的作用。     

血管紧张素转换酶2研究新进展

血管紧张素转换酶(ACE)是一种锌指金属蛋白酶,对肾素-血管紧张素系统(RAS)有关键调控作用.ACE 2主要分布在心脏、肾脏和睾丸,能水解血管紧张素(Ang)Ⅰ,产生Ang 1-9,还能水解RAS中的主要物质AngⅡ,产生具有血管扩张作用的Ang 1-7.研究表明ACE 2可能在RAS中扮演与ACE相反的角色,达到血管收缩和舒张之间的平衡,与高血压、心力衰竭及糖尿病肾病等关系密切.     

血管紧张素转换酶2及其转换产物对心血管系统的作用

新近发现一种血管紧张素转换酶(ACE)同类酶,命名为血管紧张素转换酶2(ACE2),此酶在结构、功能等方面与ACE有所 不同,其转换产物血管紧张素-(1-9)和血管紧张素-(1-7)在功能上与血管紧张素转换酶转换产物AngⅡ部分相拮抗。本文就此酶 及其产物的研究做一综述。     

血管紧张素转换酶2与心血管系统

血管紧张素转换酶2(ACE2)是2000年由国外学者发现的一个新的锌脂金属蛋白酶,对肾素-血管紧张素系统(RAS)具有关键性调控作用。主要由心脏、肾脏、睾丸的血管内皮细胞表达。因其内含有一个HEXXH锌结合体motif,并在这一结合体附近与血管紧张素转换酶(ACE)高度同源[1],故称ACE2或血管转换酶同源体(ACEH)。能水解血管紧张素Ⅰ(AngⅠ),产生AngⅠ-9,水解血管紧张素Ⅱ(AngⅡ),产生AngⅠ-7[2]。ACE2在RAS中的作用与ACE相反,保持血管的收缩与舒张平衡,与高血压、心力衰竭(心衰)及冠心病等相关。1 ACE2的生物学特性1.1 ACE2的结构及功…     

血管紧张素转换酶2研究进展

血管紧张素转换酶2是一种金属钛酶,它将血管紧张素I、血管紧张素Ⅱ分别水解为血管紧张素（1～9）及具有血管舒张、抗增殖的血管紧张素（1～7）。血管紧张素转换酶2参与了肾素-血管紧张素-醛固酮系统中多种肽的代谢过程,与高血压、肾脏疾病、糖尿病等发生相关,对心脏、肾脏有一定保护作用,进一步研究其参与保护的机制,有可能为心血管病治疗提供新的靶点。     

血管紧张素转换酶2在高血压发病机制中的角色

血管紧张素转换酶2是近来被发现肾素-血管紧张素-醛固酮系统中新的代谢酶,不同于血管紧张素转换酶的作用,血管紧张素转换酶2能对血压进行负向调节,对抗血管紧张素转换酶的作用。现对血管紧张素转换酶2的特性及与高血压发病机制中的角色进行综述。     

血管紧张素转换酶2研究进展

血管紧张素转换酶(ACE)是一种锌指金属蛋白酶,对肾素—血管紧张素系统(RAS)有关键调控作用。ACE2是最近在啮齿类动物和人类中发现的一种ACE相关的羧基肽酶,主要分布在心脏、肾脏和睾丸。ACE2能水解血管紧张素(Ang)Ⅰ,产生Ang-(1-9),还能水解RAS中的主要物质AngⅡ,产生具有血管扩张作用的Ang-(1-7)。很多研究表明,ACE2可能在RAS中扮演与ACE相反的角色,以达到血管收缩和舒张的平衡,并与高血压的发生关系密切。ACE2基因敲除小鼠的心功能受到损害。糖尿病肾病小鼠肾小管的ACE2水平明显下降,提高ACE2水平则可能预防糖尿病肾病的发生和进展。但ACE2的具体作用机制还需进一步研究。     

血管紧张素转换酶2与高血压

血管紧张素转换酶2与血管紧张素转换酶一样参与肾素-血管紧张素系统中血管紧张素的代谢。它通过将血管紧张素Ⅱ水解成血管紧张素1-7对抗血管紧张素转换酶-血管紧张素Ⅱ代谢轴,是平衡肾素-血管紧张素系统内部调节的另一血管紧张素代谢通路。这种系统的内部调节在调节心血管系统活动中起重要作用,其平衡的破坏与高血压等相关疾病的发生发展密切相关,通过调节血管紧张素2来治疗高血压及其并发症可能是本世纪高血压治疗学上的新靶点。     

由血管紧张素(1-7)重新认识RAS系统

对血管紧张素 (1- 7)的研究使我们对肾素 -血管紧张素系统 (RAS)有了更全面的认识。血管紧张素 (1-7)通过特异性的受体发挥生理作用。血管紧张素Ⅰ和血管紧张素Ⅱ经过特异的肽链内切酶变为血管紧张素 (1 -7) ,再经血管紧张素转换酶作用降解为无活性的血管紧张素 (1- 5 )。血管紧张素 (1- 7)具有抗增殖、扩张血管、抗氧化应激及促进纤溶的作用。     

血管紧张素转换酶2对心血管系统疾病影响的研究进展

<正>肾素-血管紧张素系统(RAS)在心血管功能的调解中发挥重要作用。血管紧张素(Ang)Ⅰ是Ang原在肾素的作用下水解而成的,而具有生物活性的AngⅡ是AngⅠ在血管紧张素转换酶(ACE)的催化作用下生成,具有收缩血管、水钠潴留等一系列生物学活性,是RAS中最重要的物质之一。随着人们对RAS的不断深入研究发现,ACE2作为ACE的同系物,可以催化AngⅡ生成具有舒张血管、抗炎、抗纤维化、抗细胞增殖等多种生物学活性的物质Ang1～7。Clar     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.     

Response of rat pineal melatonin to calcium, magnesium, and lithium is circadian stage dependent

Abstract: Herein we documented the response of pineal melatonin production to electrolytes known to be effective on pineal function in view of a possible circadian stage dependence. We studied the release of melatonin by perifused rat pineal glands at 2 different circadian stages corresponding to the middle of the light and dark periods, i.e., respectively, 7 and 19 HALO (Hours After Light Onset, L:D = 12:12). The initial efflux rates were, as expected, much higher in the perifusates of glands removed from rats sacrificed during the dark phase than of those removed during the light phase. After 3 hr of perifusion, melatonin release reached similar levels which were found constant up to the 8th hr of perifusion, whatever the circadian stage. Perifusion of the glands with physiological concentrations for the rat of calcium (5.2 mmol/1) and magnesium (1.34 mmol/1) resulted in a stimulatory effect on the pineal glands removed from rats sacrificed in the middle of the dark period (19 HALO), whereas no effects were observed on the pineal glands removed from rats sacrificed during the light (7 HALO). Lithium (0.28 and 0.55 mmol/1) was ineffective on melatonin release in pineal glands removed 7 and 19 HALO. Our results show differences in the initial efflux rates of melatonin and in the response of perifused pineal glands to calcium and magnesium according to the circadian stage.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Presence of immunoreactive growth hormone and prolactin in the ovine pineal gland

Abstract: The use of antisera raised against bovine growth hormone (GH) and ovine prolactin (PRL) enabled the detection of related immunoreactive (ir) sequences of proteins in ovine pineal tissue. The isolation of PRL-like ir-material was accomplished using a 0.25 M ammonium sulphate (pH 5.5) extraction followed by ethanol precipitation, whereas the resulting 2.0 M ammonium sulphate (pH 7.0) precipitate contained a GH-like immunoreactivity. Gel chromatography of the GH-like immunoreactivity (Sephadex G-100) indicated the presence of several GH-like fragments ranging in the M_r range of 7,000 to 55,000. Analyses of the PRL-like ir-material found in pineal tissue on HPLC using a TSK 545-DEAE column led to the resolution into a single peak of immunoreactivity. A single peak of activity was also observed following chromatofocusing and hydrophobic interaction chromatography of the ir-peak from the TSK 545-DEAE column. The PRL-like ir-material inhibited the binding of [¹²⁵I]ovine PRL-S14 to anti-ovine PRL antibodies without showing an affinity for binding to anti-rat PRL or anti-bovine GH antibodies. Scatchard analysis of the binding of pineal PRL-like ir-material and pituitary ovine PRL-S14 to liver membranes from day-20 pregnant rats revealed similar affinity constants (K_a of 4.7 ± 0.2 × 10⁹ M^-1). In addition, the replication of Nb 2 Node rat lymphoma cells was stimulated by pineal PRL-like ir-material, an effect known to be specific for lactogenic hormones. The pineal PRL-like immunoreactivity appeared on sodium dodecyl sulfate polyacrylamide gels as a single major band of M_r 24,000. The functional status of PRL-and GH-like ir-material in the ovine pineal remains to be determined, but evidence is presented that the overall protein synthesis rate of the rat pineal responded to circulating concentrations of PRL.     

Microbiology of human immunodeficiency virus anorectal disease

PURPOSE: Individuals who are seropositive for the human immunodeficiency virus are at high risk for opportunistic infection and anorectal disorders. Little prospective information is available regarding anorectal pathogens in these patients. METHODS: One hundred sixty-three HIV-seropositive patients presented to the colorectal clinic between 1989 and 1992. Forty-seven (29 percent) patients were thought to have an infectious process and were prospectively studied using a standardized multiculture protocol. RESULTS: Mean age was 33 (range, 19–59) years. All were male; high-risk behavior accounted for 87 percent of HIV transmissions. Presenting complaints included anorectal pain (79 percent), pus per anum (28 percent), and blood per anum (26 percent). Examination revealed perianal tenderness (60 percent), condyloma (38 percent), perianal ulcers (38 percent), and anal fissures (34 percent). Sixty-six sets of cultures were performed; 28 patients had one set, 15 had two sets, and 4 had three sets. Thirty-two of these 47 patients (68 percent) had positive cultures including herpes (50 percent), cytomegalovirus (25 percent),Neisseria gonorrhoeae (16 percent), chlamydia (16 percent), acidfast bacilli (2 percent), and others (9 percent). Six of 32 patients with positive cultures had more than one organism cultured. Sixteen (50 percent) patients with positive cultures were treated medically, 8 (25 percent) were treated surgically and 8 (25 percent) were treated with both modalities. Sixty-one procedures were performed on 17 patients for condylomata. Eighteen patients had 20 procedures for abscesses, 50 percent of whom had positive cultures for other than common bowel flora; all improved. Fourteen patients underwent 33 procedures for perianal fistulas.Mycobacterium fortuitum was cultured from one patient who required 13 procedures for abscesses and fistulas. Forty-five (96 percent) patients were followed for an average of 12.5 months ±2.9 SEM (range, 1–94 months). Symptoms were improved or resolved in 22 of 32 (69 percent) patients with positive cultures and in 11 of 13 (84 percent) with negative cultures. CONCLUSIONS: Specific pathogens may often be identified in human immunodeficiency virus-seropositive patients with anorectal disorders if aggressively sought. Although patients without specific pathogens identified may be expected to improve with planned empiric treatment, positive identification allows more directed therapy.