脑梗死后神经干细胞的活化和移植

脑梗死后,缺血核心神经细胞的死亡不可避免。成年哺乳动物脑室下层(SVZ)和海马齿状回颗粒下层(SGZ)等保持着神经发生。脑梗死可促进神经发生。存在于这些部位的神经干细胞(NSC)具有自我更新和多向分化潜能。近年来,NSC的激活和向梗死灶周围迁移等机制逐渐为人们所认识,采取适当的措施激活脑内自然的神经发生、移植外源性NSC治疗脑梗死的研究,给脑梗死后缺损组织结构和功能的修复带来了希望。     

神经干细胞与脑缺血

神经干细胞（NSC）在脑缺血时发生增殖，迁移和分化，以修复损伤的神经功能，NSC移植可用于防治脑缺血。     

缺血缺氧性脑损伤治疗的新方法——神经干细胞移植

神经干细胞（NSC）是一群较原始的，能自我更新并具有多种分化潜能的细胞，可分化成神经元，少突胶质细胞和星形细胞。在生理条件下，体现人的NSC通常保持静息状态；神经损伤后，内源性NSC可因微环境的改变而被激活，迁移和分化 。以替代损伤的细胞和重建神经环路；遗传修饰后，外源性NSC移植显示了很大的治疗潜力，为今后缺血缺氧性脑损伤的治疗提供了新的手段。     

缺血缺氧性脑损伤治疗的新方法--神经干细胞移植

神经干细胞(NSC)是一群较原始的、能自我更新并具有多种分化潜能的细胞,可分化成神经元、少突胶质细胞和星形细胞.在生理条件下,体内的NSC通常保持静息状态;神经损伤后,内源性NSC可因微环境的改变而被激活、迁移和分化,以替代损伤的细胞和重建神经环路;遗传修饰后,外源性NSC移植显示了很大的治疗潜力,为今后缺血缺氧性脑损伤的治疗提供了新的手段.     

神经干细胞与神经营养因子

神经干细胞（NSC）增殖是神经发育早期阶段的主要事件，在此阶段，NSC通过10—12次分裂进行增殖，为后期神经发生提供足够的细胞来源。此外，当脑组织受损时，内源性NSC也可增殖并分化，补偿缺失的神经细胞，部分修复神经功能。神经营养因子（NTF）是一类对神经元有特异性保护作用的内分泌多肽，它可促进体内、外培养神经元存活及突起生长。1952年Levi—Montalcini在研究鸡胚的神经发育过程中发现了神经生长因子（NGF），此后几十年，新的NTF不断被发现，并形成了NTF大家族。它们来源于靶细胞逆向营养神经元，促进和维持神经细胞生长、存活，修复神经细胞功能。在胚胎发育早期，NTF如碱性成纤维细胞生长因子（bFGF）、表皮生长因子（EGF）等能显著促进NSC的增殖与分化。     

BDNF基因修饰神经干细胞移植对脊髓损伤后红核神经元作用的实验研究

将20只SD大鼠随机分为假手术组、脊髓损伤组（SCI组），神经干细胞（NSC）组（NSC组）及脑源性神经营养因子（BDNF）基因修饰NSC组（BDNF组）各5只。假手术组仅行椎板切开术；余三组采用电控脊髓损伤打击装置致脊髓损伤模型，术后3d SCI组脊髓内注射生理盐水溶液5μl；NSC组注射NSC悬液5μl，BDNF组注射NSC-BDNF悬液5μl。术后观察各组行为学（BBB）评分和红核神经元存活情况。结果BDNF组BBB评分显著高于SCI组、NSC组．红核神经元数目均多于SCI组、NSC组（P均〈0．01）。提示BDNF基因修饰NSC移植对脊髓损伤后红核神经元有保护作用。     

BDNF基因修饰神经干细胞移植对大鼠脊髓损伤后神经细胞凋亡的影响

采用电控大鼠脊髓损伤打击装置致大鼠脊髓损伤模型。将120只SD大鼠随机分为假手术组（Sham组）、脊髓损伤组（SCI组）、神经干细胞组（NSC组）、BDNF基因修饰神经干细胞组（NSC—BDNF组）。免疫组织化学法检测各组脊髓BDNF、Bax、Bcl-2的表达，流式细胞仪检测脊髓细胞凋亡率。结果 NSC—BDNF组BDNF免疫阳性细胞光密度值较NSC、SCI组明显增加（P〈0．05），表达时间及高峰延长；且Bcl-2蛋白表达较其他组在各时点均增高（P均〈0．05）。而Bax蛋白表达较其他组在各时点均降低（P均〈0．01）。凋亡率亦降低（P均〈0．01）。提示BDNF基因修饰NSC可在损伤脊髓内有效表达。且明显促进脊髓损伤后Bcl-2的高表达，抑制Bax的表达，从而降低神经细胞的凋亡率。     

缺血性中风后遗症神经功能重建的可能机制

中风后遗症是指中风病急性期经治疗缓解后遗留的偏瘫、失语、认知功能障碍等症状。传统观点认为，成年中枢神经系统（CNS）损伤后缺乏自身修复能力，因此认为，脑梗死后只有在急性期针对半暗带治疗才有价值，后遗症期即无治疗意义。但近年来研究证实，人及动物成年脑内有多处部位存在着自我更新和分化潜能的静息态神经干细胞（NSC），可参与修复缺损的神经功能。临床实践发现，有些缺血性中风患者即使在患病数年后，经治疗仍可出现功能恢复，即神经功能重建，但其机制尚不清楚。本文根据近年来最新的研究进展．从下调脑区激活、中枢神经再生、有效突触重建、神经影响因子和相关基因的调控等方面，综述缺血性卒中后遗症神经功能重建的可能机制。     

脑缺血后的神经和血管发生

成年脑内存在神经干细胞（NSC），脑缺血后室管膜，室下区和海马齿状回的NSC因微环境改变而被激活。并参与机体的损伤修复反应。同时，作为对缺血的另一种代偿反应，半暗带内的骨髓源性内皮细胞，脑血管内皮细胞增殖迁移，巨噬细胞浸润增加，并使新生血管形成，两个过程密切相关，共同完成缺血后的脑组织修复。     

银杏内酯B促进体外分化的神经干细胞神经突起生长的研究

目的：观察银杏内酯B（GKB）对体外分化的神经干细胞（NSC）神经突起生长的影响，并初步探讨其可能的机制。方法：用含不同浓度（20mg／L、40mg／L、60mg／L）GKB的分化培养基培养NSC，在不同时间点测量细胞突起的数量和长度，在第7天时应用免疫荧光染色法检测细胞因子信号转导抑制因子-2（SOCS2）表达。结果：（1）24h和3d时各GKB组NSC神经突起长度和数量均较对照组显著增加（P〈0．01）；40mg／L和60mg／LGKB组NSC神经突起数量和平均长度较20mg／LGKB组显著增加（P〈0．01），但两者之间无显著差异。（2）各GKB组和对照组3d时NSC神经突起长度比24h时显著增加（P〈0．01）；对照组3d时NSC神经突起数量与24h时无显著差异，而相同GKB组间NSC平均神经突起数量均显著增加（P〈0．01）。（3）各GKB组SOCS2免疫反应物平均吸光度分别为1．382、1．578和1．527，均显著高于对照组（1．134，P〈0．01）；40mg／L和60mg／LGKB组SOCS2免疫反应物平均吸光度显著高于20mg／LGKB组（P〈0．01），但40mg／LGKB组与60mg／LGKB组无显著差异。结论：GKB能够促进体外分化的NSC神经突起生长，表现为神经突起数量和长度增加；其作用机制可能与SOCS2表达上调有关。     

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.     

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.     

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.     

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.