共查询到20条相似文献，搜索用时 15 毫秒
1.
Tolerance induced by thymic epithelial grafts in birds 总被引：8，自引：0，他引：8
Grafts of the anterior limb bud introduced at embryonic day 4 between histoincompatible chick embryos were subject to chronic, mild rejection beginning from several weeks to several months after birth. In contrast, quail wing buds similarly grafted into chickens started to be rejected at the first or second week after birth and finally autoamputated. Embryonic thymus epithelium from donor quail (before it had been colonized by hemopoietic cells) was grafted into chicks. A chimeric thymic epithelial stroma was generated in which the lymphocytes of the chick acquired the capacity to recognize the grafted limb as self either permanently or for a protracted period of time. In such thymic chimeras the grafted wings were not rejected. 相似文献
2.
Neocortical transplants in the mammalian brain lack a blood-brain barrier to macromolecules 总被引：3，自引：0，他引：3
J M Rosenstein 《Science (New York, N.Y.)》1987,235(4790):772-774
In order to determine whether the blood-brain barrier was present in transplants of central nervous tissue, fetal neocortex, which already possesses blood-brain and blood-cerebrospinal fluid barriers to protein, was grafted into the undamaged fourth ventricle or directly into the neocortex of recipient rats. Horseradish peroxidase or a conjugated human immunoglobulin G-peroxidase molecule was systemically administered into the host. These proteins were detected within the cortical transplants within 2 minutes regardless of the age of the donor or postoperative time. At later times these compounds, which normally do not cross the blood-brain barrier, inundated the grafts and adjacent host brain and also entered the cerebrospinal fluid. Endogenous serum albumin detected immunocytochemically in untreated hosts had a comparable although less extensive distribution. Thus, transplants of fetal central nervous tissue have permanent barrier dysfunction, probably due to microvascular changes, and are not integrated physiologically within the host. Blood-borne compounds, either systemically administered or naturally occurring, which should never contact normal brain tissue, have direct access to these transplants and might affect neuronal function. 相似文献
3.
D E Redmond F Naftolin T J Collier C Leranth R J Robbins C D Sladek R H Roth J R Sladek 《Science (New York, N.Y.)》1988,242(4879):768-771
Studies in animals suggest that fetal neural grafts might restore lost neurological function in Parkinson's disease. In monkeys, such grafts survive for many months and reverse signs of parkinsonism, without attendant graft rejection. The successful and reliable application of a similar transplantation procedure to human patients, however, will require neural tissue obtained from human fetal cadavers, with demonstrated cellular identity, viability, and biological safety. In this report, human fetal neural tissue was successfully grafted into the brains of monkeys. Neural tissue was collected from human fetal cadavers after 9 to 12 weeks of gestation and cryopreserved in liquid nitrogen. Viability after up to 2 months of storage was demonstrated by cell culture and by transplantation into monkeys. Cryopreservation and storage of human fetal neural tissue would allow formation of a tissue bank. The stored cells could then be specifically tested to assure their cellular identity, viability, and bacteriological and virological safety before clinical use. The capacity to collect and maintain viable human fetal neural tissue would also facilitate research efforts to understand the development and function of the human brain and provide opportunities to study neurological diseases. 相似文献
4.
Biohybrid artificial pancreas: long-term implantation studies in diabetic, pancreatectomized dogs 总被引：5，自引：0，他引：5
S J Sullivan T Maki K M Borland M D Mahoney B A Solomon T E Muller A P Monaco W L Chick 《Science (New York, N.Y.)》1991,252(5006):718-721
Diabetic complications such as neuropathy, retinopathy, and renal and cardiovascular disease continue to pose major health risks for diabetic patients. Consequently, much effort has focused on approaches that could replace conventional insulin therapy and provide more precise regulation of blood glucose levels. The biohybrid perfused artificial pancreas was designed to incorporate islet tissue and a selectively permeable membrane that isolates this tissue from the immune system of the recipient. Biohybrid pancreas devices containing canine islet allografts were implanted in ten pancreatectomized dogs requiring 18 to 32 units of injected insulin daily. These implants resulted in good control of fasting glucose levels in six of these animals without further exogenous insulin for periods of up to 5 months. 相似文献
5.
Newly formed small lymphocytes with a short life-span in the blood are the only cells from thoracic duct lymph which accumulate in acutely inflamed tissue. This conclusion is drawn from studies in which rats with induced peritonieal exudates were injected intravenously with radioactively labeled thoracic duct cells. Radioactivity, originally vested in newly formed donor small lymphocytes, was found later in a small number of similar exudate cells. Small lymphocytes generated 10 days or more before the thoracic ducts were cannulated failed to localize in peritoneal exudates, although the cells moved in large numbers from the blood in to lymph nodes. 相似文献
6.
Implantation of genetically engineered fibroblasts into mice: implications for gene therapy 总被引：7，自引：0，他引：7
R F Selden M J Skoskiewicz K B Howie P S Russell H M Goodman 《Science (New York, N.Y.)》1987,236(4802):714-718
In a variety of human genetic diseases, replacement of the absent or defective protein provides significant therapeutic benefits. As a model for a somatic cell gene therapy system, cultured murine fibroblasts were transfected with a human growth hormone (hGH) fusion gene and cells from one of the resulting clonal lines were subsequently implanted into various locations in mice. Such implants synthesized and secreted hGH, which was detectable in the serum. The function of the implants depended on their location and size, and on the histocompatibility of the donor cells with their recipients. The expression of hGH could be modified by addition of regulatory effectors, and, with appropriate immunosuppression, the implants survived for more than 3 months. This approach to gene therapy, here termed "transkaryotic implantation," is potentially applicable to many genetic diseases in that the transfected cell line can be extensively characterized prior to implantation, several anatomical sites are suitable for implantation, and regulated expression of the gene of therapeutic interest can be obtained. 相似文献
7.
The drug, 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP), depletes striatal dopamine levels in primates and certain rodents, including mice, and produces parkinsonian-like symptoms in humans and nonhuman primates. To investigate the consequences of grafting adrenal medullary tissue into the brain of a rodent model of Parkinson's disease, a piece of adult mouse adrenal medulla was grafted unilaterally into mouse striatum 1 week after MPTP treatment. This MPTP treatment resulted in the virtual disappearance of tyrosine hydroxylase-immunoreactive fibers and severely depleted striatal dopamine levels. At 2, 4, and 6 weeks after grafting, dense tyrosine hydroxylase-immunoreactive fibers were observed in the grafted striatum, while only sparse fibers were seen in the contralateral striatum. In all cases, tyrosine hydroxylase-immunoreactive fibers appeared to be from the host rather than from the grafts, which survived poorly. These observations suggest that, in mice, adrenal medullary grafts exert a neurotrophic action in the host brain to enhance recovery of dopaminergic neurons. This effect may be relevant to the symptomatic recovery in Parkinson's disease patients who have received adrenal medullary grafts. 相似文献
8.
本试验以具无融合生殖特性的4 年生湖北海棠实生树为试材, 以1 年生实生苗和4 年生成年芽嫁接树作为4 年生实生树的童区和成年区的对照。从空间角度对不同高度位置叶片的解剖结构进行研究。结果显示:多年生实生树叶片的解剖结构随叶位上升, 逐由阴性结构转变为阳性结构, 其叶片厚度、栅栏组织和海绵组织厚度, 细胞形状指数等均随叶片位置高度上升而增加。单位刻度内的栅栏组织细胞排列数却不随高度而发生变化, 且在成年芽嫁接树与实生树之间也无差异。成年芽嫁接树叶片的海绵组织厚度不随高度而发生变化, 但细胞形状指数、叶片和栅栏组织厚度等与多年生实生树具相同变化趋势, 也具有由阴性结构向阳性结构转变的特点。解剖结构特征不宜作阶段转变的指标。 相似文献
9.
Identification and characterization of the protein encoded by the human N-myc oncogene 总被引：22，自引：0，他引：22
D J Slamon T C Boone R C Seeger D E Keith V Chazin H C Lee L M Souza 《Science (New York, N.Y.)》1986,232(4751):768-772
The human N-myc gene is related to the c-myc proto-oncogene, and has been shown to have transforming potential in vitro. Many studies have reported amplification of N-myc in human neuroblastoma and retinoblastoma cell lines. In primary tumors, amplification of the gene was found to correlate directly with behavior of the tumor. Specific restriction fragments of a partial complementary DNA clone of N-myc from LA-N-5 human neuroblastoma cells were placed into a bacterial expression vector for the purpose of producing antigens representative of the N-myc protein. Rabbits immunized with these antigens produced antisera that recognized a protein of 62-64 kilodaltons in neuroblastoma cells. By several criteria, this protein appears to be part of the same proto-oncogene family as the c-myc protein. Moreover, the antisera to fragments of this protein were capable of histochemically identifying malignant cells in clinical specimens. 相似文献
10.
利用基因枪技术转化小麦、玉米的研究 总被引：2，自引：0，他引：2
采用国产JQ－700型基因枪,以含Bt基因的质粒pHB101为供体,轰击小麦、玉米愈伤组织,轰击后的愈伤组织经潮霉素抗性筛选后,获得32株小麦再生苗,14株玉米抗性植株。以a－32P－dCTP标记的PHB101质粒为探针,对小麦抗性植株进行点杂交印渍检测,发现有15株小苗显示阳性信号,且其中有一株的后代对田间蚜虫及锈病的抗性较好。玉米再生植株种植田间后在其后代中选出一抗玉米螟的稳定株系,尚需进一步的分子验证和饲虫实验。 相似文献
11.
Pathogenesis of a local graft versus host reaction: immunogenicity of circulating host leukocytes 总被引：12，自引：0，他引：12
A local invasive-destructive reaction typical of that seen in allograft rejection occurs when Lewis rat spleen cells are inoculated under the capsule of Lewis kidney freshly grafted into F(1) hybrid hosts. Thus the donor lymphoid cells can be immunogenically stimulated by circulating host leukocytes and the interaction of these two cell populations results in nonspecific damage to kidney parenchyma. The results indicate that passenger leukocytes in organ allografts may be important immunogenic agents. 相似文献
12.
目的观察小陷胸汤对小鼠及大鼠血液中、脑组织中5-HT(5-羟色胺)、GABA(r-氨基丁酸)镇静安神作用的影响。方法将50只KM种小鼠随机分为空白组、地西泮组、小陷胸汤高、中、低剂量组,灌胃7 d,观察各组小鼠的睡眠时间;将32只大鼠随机分为空白组、地西泮组、小陷胸汤组、小陷胸汤加地西泮组,于造模第8天开始,各组分别以不同药物连续灌胃8 d后,测定血液和脑组织中5-HT和GABA浓度。结果对小陷胸汤小鼠中剂量组与空白组平均睡眠持续时间比较差异有统计学意义(P<0.05)。小陷胸汤组大鼠与空白组血液和脑组织中GABA及5-HT浓度比较差异有统计学意义(P<0.05)。结论小陷胸汤能够对小鼠和大鼠产生镇静安神作用,其作用机制可能与提高5-HT、GABA的浓度有关。 相似文献
13.
Kodama S Kühtreiber W Fujimura S Dale EA Faustman DL 《Science (New York, N.Y.)》2003,302(5648):1223-1227
Nonobese diabetic (NOD) mice are a model for type 1 diabetes in humans. Treatment of NOD mice with end-stage disease by injection of donor splenocytes and complete Freund's adjuvant eliminates autoimmunity and permanently restores normoglycemia. The return of endogenous insulin secretion is accompanied by the reappearance of pancreatic beta cells. We now show that live donor male or labeled splenocytes administered to diabetic NOD females contain cells that rapidly differentiate into islet and ductal epithelial cells within the pancreas. Treatment with irradiated splenocytes is also followed by islet regeneration, but at a slower rate. The islets generated in both instances are persistent, functional, and apparent in all NOD hosts with permanent disease reversal. 相似文献
14.
The type and fate of mononuclear cells of guinea pigs hypersensitive to tuberculin were studied by means of purified protein derivative labeled with I(125) and mononuclear cells labeled with tritiated thymidine. Purified protein derivative labeled with I(125) was taken up in vitro by lymphocytes and neutrophils from animals that were either sensitive or nonsensitive to tuberculin, but it was bound more frequently by the cells of sensitive animals. Passive transfer of tuberculin hypersensitivity by means of lymphocytes labeled with tritiated thymidine indicated that significant numbers of radioactive cells migrated to the site where the skin was tested with purified protein derivative only when the test was made immediately after transfusion. Although skin reactions from tests made with purified protein derivative 24 hours after transfusion were comparable to those from tests made immediately, the number of labeled cells at the sites of the later tests was not consistently larger than it was in controls (Histoplasmin reactions). Thus transfused tuberculin-sensitive cells are neither always attracted to the sites of the test with purified protein derivative nor are they required in large numbers at the site for a positive reaction to develop. 相似文献
15.
Brain grafts reduce motor abnormalities produced by destruction of nigrostriatal dopamine system 总被引：27，自引：0，他引：27
M J Perlow W J Freed B J Hoffer A Seiger L Olson R J Wyatt 《Science (New York, N.Y.)》1979,204(4393):643-647
In order to determine if brain tissue grafts can provide functional input to recipient central nervous system tissue, fetal rat dopamine-containg neurons were implanted adjacent to the caudate nucleus of adult recipients whose endogenous dopaminergic input had been destroyed. The grafts showed good survival and axonal outgrowth. Motor abnormalities, which had been induced by the destruction of the endogenous dopaminergic input to the caudate, were significantly reduced after grafting of the fetal brain tissue. These data suggest that such implants may be potentially useful in reversing deficits after circumscribed destruction of brain tissue. 相似文献
16.
目的探讨以明胶和京尼平粘合自体颗粒骨修复新西兰大白兔桡骨缺损的效果,为临床应用提供依据。方法取24只新西兰大白兔制成双侧前臂桡骨中段骨缺损模型,并将切除的骨质磨成颗粒骨,随机分为A、B、C、D4组,每组为6只,A组为空白组不填充任何材料;B组单纯填充明胶、京尼平;C组单纯植入400mg自体颗粒骨;D组填充明胶、京尼平＋200mg自体颗粒骨。各组术后2．4、8周时各处死动物兔2只,取材检测,通过观察大体标本、X线片、组织学检查评估骨缺损修复能力。结果在术后各时期,A、B组骨缺损模型均无骨愈合迹象,形成陈旧性骨缺损。术后C、D组均有良好的骨修复效果,但D组在防止颗粒骨移位流失、骨融合程度、新骨形成量、骨塑形改建方面优于C组。结论明胶、京尼平具有粘合自体颗粒骨修复骨缺损的能力。 相似文献
17.
Migration and differentiation of cerebral cortical neurons after transplantation into the brains of ferrets 总被引：4，自引：0，他引：4
S K McConnell 《Science (New York, N.Y.)》1985,229(4719):1268-1271
Cells from the cerebral proliferative zones of newborn ferrets were labeled with tritiated thymidine and a fluorescent dye and were transplanted as a single-cell suspension into the occipital region of newborn ferrets. The transplanted cells became thoroughly integrated into the host environment: many cells migrated through the intermediate zone and into the cortical plate, where they developed as pyramidal neurons. Other transplanted cells came to resemble glial cells. After 1 to 2 months most transplanted neurons had taken up residence in layer 2 + 3, the normal destination of neurons generated on postnatal days 1 and 2. Thus the sequence of morphological differentiation and the eventual laminar position of the isochronically transplanted neurons closely paralleled that of their normal host counterparts. 相似文献
18.
Labeled putrescine as a probe in brain tumors 总被引：1，自引：0，他引：1
N Volkow S S Goldman E S Flamm H Cravioto A P Wolf J D Brodie 《Science (New York, N.Y.)》1983,221(4611):673-675
The polyamine metabolism of transplanted N-nitrosomethylurea-derived rat glioma was determined with radiolabeled putrescine used as a marker for malignancy. The uptake of putrescine in vivo was complete within 5 minutes and was specific for tumor tissue. The conversion of putrescine to spermine and other metabolites by the tumor was rapid, in contrast to the case for adjacent normal brain. These results suggest that putrescine labeled with carbon-11 may be used as a positron-emission tomographic tracer for the selective metabolic imaging of brain tumor and may be used in an appropriate model as a marker for tumor growth rate. 相似文献
19.
探讨骨髓间充质干细胞(MSCs)移植对大鼠脑缺血的修复和治疗.体外分离培养大鼠MSCs,以Hoeschst33342标记,移植到大脑中动脉梗塞(MCAO)模型的大鼠体内,分别设立缺血1 d和缺血7 dMSCs移植组与缺血对照组,对各组大鼠进行神经功能损害严重程度评分(NSS)及大脑组织切片观察比较.结果发现,缺血1 d MSCs移植组大鼠NSS评分低于另外两组,差异显著(P＜0.05),大脑组织结构清晰、完整,胶质瘢痕少;缺血7 d MSCs移植组与对照组无明显差异(P＞0.05).故缺血早期进行MSCs移植,大鼠神经功能恢复情况明显.MSCs在损伤后的脑组织内能够存活并且分化为神经元、胶质细胞等,对动物神经损伤后组织重建及功能恢复有一定的治疗作用. 相似文献
20.
Immunohistochemistry of adenosine deaminase: implications for adenosine neurotransmission 总被引：11，自引：0，他引：11
Immunohistochemical analysis of adenosine deaminase in rat brain revealed an extensive plexus of adenosine deaminase-containing neurons in the basal hypothalamus. These neurons converged on and were most numerous in three major centers, namely, the tuberal, caudal, and postmammillary caudal magnocellular nuclei. Most other brain regions were devoid of cells containing adenosine deaminase. Some adenosine deaminase-containing neurons were retrogradely labeled with the fluorescent dye fast blue when the dye was injected into the frontal cortex and striatum. Specific populations of neurons having high levels of adenosine deaminase may release adenosine as a neurotransmitter. 相似文献