胰岛β细胞凋亡的分子机制

胰岛β细胞凋亡在糖尿病的发病中扮演重要角色,1、2型糖尿病β细胞凋亡的分子机制有所不同。在1型糖尿病中,胰岛β细胞主要通过死亡受体介导的信号转导途径及颗粒酶B途径发生凋亡,而在2型糖尿病中,线粒体途径是胰岛β细胞凋亡的主要信号转导途径。多种细胞因子通过激活核转录因子调节相应基因表达,进而调控胰岛β细胞的凋亡。     

β细胞凋亡与2型糖尿病

2型糖尿病β细胞凋亡增加.首先β细胞内胰淀素沉积,通过细胞膜毒性作用导致细胞凋亡.其次高血糖通过调节β细胞Bcl家族水平、白介素(IL)-1β/核因子-κB和己糖胺介导的路径,游离脂肪酸通过神经酰胺、Caspase、Bcl-2、过氧化物体增殖物活化受体介导的路径诱导β细胞凋亡.此外,高糖和游离脂肪酸还存在共同通路--氧化应激,且二者具有协同效应.了解2型糖尿病胰岛β细胞凋亡的机制,对深入认识糖尿病的发病机制和致病过程,更好地防治2型糖尿病具有重要意义.     

丝裂素活化蛋白激酶与1型糖尿病

丝裂素活化蛋白激酶（MAPK）参与了胰岛β细胞凋亡，很多细胞因子及应激刺激可激活MAPK信号转导通路，诱导胰岛β细胞凋亡。MAPK也可通过降低胰岛素样生长因子（IGF）水平而诱导胰岛β细胞凋亡，导致1型糖尿病的发生。探索MAPK信号转导通路在1型糖尿病发病中的作用，为预防1型糖尿病的发生提供新的理论基础。     

丝裂素活化蛋白激酶与1型糖尿病

丝裂素活化蛋白激酶 (MAPK)参与了胰岛 β细胞凋亡 ,很多细胞因子及应激刺激可激活MAPK信号转导通路 ,诱导胰岛β细胞凋亡。MAPK也可通过降低胰岛素样生长因子 (IGF)水平而诱导胰岛β细胞凋亡 ,导致 1型糖尿病的发生。探索MAPK信号转导通路在 1型糖尿病发病中的作用 ,为预防 1型糖尿病的发生提供新的理论基础     

硫氧还蛋白相互作用蛋白在糖尿病发病中的作用机制

<正>糖尿病分为1型和2型糖尿病,1型糖尿病系自身免疫性疾病,其胰岛受到巨噬细胞及T细胞所产生细胞因子、干扰素及肿瘤坏死因子(TNF)-α等作用后导致胰岛β细胞凋亡;而2型糖尿病与胰岛β细胞凋亡及胰岛素抵抗有关〔1³〕。β细胞减少可导致血糖增高;而长时间高血糖作用能促使β细胞群数量逐渐减少。高水平葡萄糖所导致的胰岛炎症、氧化应激、线     

高浓度游离脂肪酸对胰岛β细胞凋亡的影响及其机制的研究进展

高浓度游离脂肪酸可导致胰岛β细胞凋亡,与2型糖尿病发生发展密切相关.其机制可能与胰岛素受体底物、代谢中关键酶、氧化应激、内质网应激、Bcl-2家族、神经酰胺途径、Caspase家族、12-脂氧合酶、蛋白激酶B、G蛋白偶联受体等有关.研究游离脂肪酸对胰岛β细胞凋亡的影响有重要的临床意义.     

β细胞凋亡与2型糖尿病

2型糖尿病β细胞凋亡增加。首先β细胞内胰淀素沉积，通过细胞膜毒性作用导致细胞凋亡。其次高血糖通过调节β细胞Bcl家族水平、白介素(IL)-1β/核因子-κB和己糖胺介导的路径，游离脂肪酸通过神经酰胺、Caspase、Bcl-2、过氧化物体增殖物活化受体介导的路径诱导8细胞凋亡。此外，高糖和游离脂肪酸还存在共同通路——氧化应激，且二者具有协同效应。了解2型糖尿病胰岛β细胞凋亡的机制，对深入认识糖尿病的发病机制和致病过程，更好地防治2型糖尿病具有重要意义。     

脂毒性与β细胞凋亡

游离脂肪酸增加可导致脂毒性,使胰岛β细胞凋亡增加,与2型糖尿病发病密切相关。其机制可能与氧化应激、内质网应激、B细胞淋巴瘤蛋白家族、神经酰胺途径、Caspase家族、过氧化物酶体增殖物激活受体途径、胰岛素受体底物-2、12-脂氧合酶、蛋白激酶B途径、G蛋白偶联受体等有关。研究脂毒性与β细胞凋亡的关系有重要意义。     

PPARγ激动剂对胰岛β细胞脂毒性的干预作用

脂毒性是导致2型糖尿病胰岛β细胞功能衰竭的重要原因之一.脂毒性可通过多种途径、多种因素促进β细胞的功能障碍和凋亡,如神经酰胺途径、内质网应激等.如何防止或延缓胰岛β细胞功能衰竭,延缓2型糖尿病的发生、发展是重要的任务.目前研究发现,过氧化物酶体增殖物活化受体(PPAR)γ激活后会逆转胰岛β细胞的脂毒性,从而对胰岛β细胞发挥保护作用.其机制主要是减少β细胞凋亡、调节脂代谢相关基因的表达或直接调控胰岛素分泌相关因子的表达、拮抗游离脂肪酸引起的炎性反应等.     

β细胞凋亡与2型糖尿病

2型糖尿病 β细胞凋亡增加。首先 β细胞内胰淀素沉积 ,通过细胞膜毒性作用导致细胞凋亡。其次高血糖通过调节β细胞Βcl家族水平、白介素 (IL) 1β/核因子 κΒ和己糖胺介导的路径 ,游离脂肪酸通过神经酰胺、Caspase、Βcl 2、过氧化物体增殖物活化受体介导的路径诱导 β细胞凋亡。此外 ,高糖和游离脂肪酸还存在共同通路———氧化应激 ,且二者具有协同效应。了解 2型糖尿病胰岛 β细胞凋亡的机制 ,对深入认识糖尿病的发病机制和致病过程 ,更好地防治 2型糖尿病具有重要意义。     

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.