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排序方式: 共有95条查询结果,搜索用时 31 毫秒
61.
62.
高寒牧区中华羊茅人工草地退化演替的数量特征研究 总被引:22,自引:4,他引:18
对中华羊茅人工草地退化演替数量特征的研究表明,植物群落组分种的数量、丰富度指数、多样性指数和均匀度指数均随演替的进程而增加,生态优势度指数呈下降趋势。对25个组分种的重要值、生态位宽度及生态位重叠值计测的结果表明,一些阔叶杂草(如细叶亚菊、西伯利亚蓼等)是退化演替过程中入侵人工草地的先锋植物,比其他杂类草具有较大的生态位宽度值,其重要值在演替过程中呈逐年上升趋势。以中华羊茅为其中一个组分种的植物种对间的生态位重叠值,在大多数情况下小于两种阔叶杂草种对间的生态位重叠值。阔叶杂草入侵是导致人工草地退化的一个重要影响因素。 相似文献
63.
Seki T Shimokawa N Iizuka H Takagishi K Koibuchi N 《Molecular and cellular biochemistry》2008,312(1-2):193-199
Scoliosis is a condition that involves an abnormal curvature and deformity of the spinal vertebrae. The genetic background
and key gene for congenital scoliosis in humans are still poorly understood. Ishibashi rats (ISR) have congenital malformation
of the lumbar vertebrae leading to kyphoscoliosis similar to that seen in humans. To understand the pathogenesis of congenital
scoliosis, we have studied the abnormality of vertebral formation and the associated gene expression in ISR. Almost all ISR
showed kyphosis or scoliosis of the lumbar vertebrae. In ISR with severe kyphosis, some vertebral disks were missing and some
vertebral bodies were fused. Of the ISR, 27% showed hemi-lumbarization of lumbar and sacral vertebrae. Homeotic transformation
of the first sacral vertebra into the seventh lumbar vertebra and the resultant loss of the fourth sacral vertebra were seen
in half of the ISR. We also found unilateral fusions and deformities of primary ossification centers of the lumbar vertebral
column in fetal ISR. Moreover, we observed that the expression levels of Hox10 and Hox11 paralogs in lumbo-sacral transitional areas of ISR were extremely low compared with those of normal rats. These results
suggest that fusion of primary ossification centers in lumbar vertebrae in the embryonic period causes scoliosis and kyphosis
and that Hox genes are involved in the occurrence of homeotic transformation in lumbo-sacral vertebrae of congenital kyphoscoliotic ISR. 相似文献
64.
Human bone-marrow-derived mesenchymal stem cells: biological characteristics and potential role in therapy of degenerative diseases 总被引:5,自引:0,他引:5
Mesenchymal stem cells (MSC) are a group of cells present in bone-marrow stroma and the stroma of various organs with the
capacity for mesoderm-like cell differentiation into, for example, osteoblasts, adipocytes, and chondrocytes. MSC are being
introduced in the clinic for the treatment of a variety of clinical conditions. The aim of this review is to provide an update
regarding the biology of MSC, their identification and culture, and mechanisms controlling their proliferation and differentiation.
We also review the current status of their clinical use. Areas in which research is needed to enhance the clinical use of
MSC are emphasized.
This work was supported by grants from the Danish Medical Research Council, Danish Center for Stem Cell Research, and Novo
Nordisk Foundation. 相似文献
65.
66.
探讨雌激素受体(ER)在绝经后女性退变性腰椎滑脱软骨终板内的表达及其意义。方法:用RT-PCR方法检测绝经后女性退变性腰椎滑脱(DS)患者的与女性腰椎管狭窄患者(SS)患者的软骨终板内雌激素受体mRNA的表达;Western blot方法检测绝经后女性退变性腰椎滑脱(DS)患者的与女性腰椎管狭窄患者(SS)患者的软骨终板内雌激素受体蛋白质的表达;用免疫组织化学法(Envision法)检测绝经后女性退变性腰椎滑脱(DS)患者的与女性腰椎管狭窄患者(SS)患者的软骨终板内雌激素受体的分布和表达;分析雌激素、雌激素受体和退变性腰椎滑脱之间的关系。结果:软骨终板中雌激素受体mRNA的表达量在绝经后女性退变性腰椎滑脱患者中较女性腰椎管狭窄患者(SS)明显下调(P<0.05);绝经后女性退变性腰椎滑脱患者的软骨终板中雌激素受体蛋白质的表达量较女性腰椎管狭窄患者(SS)明显下调(P<0.05);免疫组织化学结果显示雌激素受体在绝经后女性退变性腰椎滑脱(DS)的软骨终板中仅少量表达,在绝经后女性腰椎管狭窄患者(SS)的软骨终板中表达量较强。结论:绝经后女性退行性腰椎滑脱患者软骨终板中雌激素受体表达量较绝经后女性腰椎管狭窄患者显著下调,可能是引起绝经后女性退行性腰椎不稳高发的原因之一。 相似文献
67.
Distribution of lactate dehydrogenase in healthy and degenerative canine stifle joint cartilage 总被引:1,自引:1,他引:0
Walter EL Spreng D Schmöckel H Schawalder P Tschudi P Friess AE Stoffel MH 《Histochemistry and cell biology》2007,128(1):7-18
In dogs, degenerative joint diseases (DJD) have been shown to be associated with increased lactate dehydrogenase (LDH) activity
in the synovial fluid. The goal of this study was to examine healthy and degenerative stifle joints in order to clarify the
origin of LDH in synovial fluid. In order to assess the distribution of LDH, cartilage samples from healthy and degenerative
knee joints were investigated by means of light and transmission electron microscopy in conjunction with immunolabeling and
enzyme cytochemistry. Morphological analysis confirmed DJD. All techniques used corroborated the presence of LDH in chondrocytes
and in the interterritorial matrix of healthy and degenerative stifle joints. Although enzymatic activity of LDH was clearly
demonstrated in the territorial matrix by means of the tetrazolium–formazan reaction, immunolabeling for LDH was missing in
this region. With respect to the distribution of LDH in the interterritorial matrix, a striking decrease from superficial
to deeper layers was present in healthy dogs but was missing in affected joints. These results support the contention that
LDH in synovial fluid of degenerative joints originates from cartilage. Therefore, we suggest that (1) LDH is transferred
from chondrocytes to ECM in both healthy dogs and dogs with degenerative joint disease and that (2) in degenerative joints,
LDH is released from chondrocytes and the ECM into synovial fluid through abrasion of cartilage as well as through enhanced
diffusion as a result of increased water content and degradation of collagen. 相似文献
68.
Maria Teresa Valenti Michela Serena Luca Dalle Carbonare Donato Zipeto 《World journal of stem cells》2019,11(11):937-956
The identification of new and even more precise technologies for modifying and manipulating the genome has been a challenge since the discovery of the DNA double helix. The ability to modify selectively specific genes provides a powerful tool for characterizing gene functions, performing gene therapy, correcting specific genetic mutations, eradicating diseases, engineering cells and organisms to achieve new and different functions and obtaining transgenic animals as models for studying specific diseases. Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology has recently revolutionized genome engineering. The application of this new technology to stem cell research allows disease models to be developed to explore new therapeutic tools. The possibility of translating new systems of molecular knowledge to clinical research is particularly appealing for addressing degenerative diseases. In this review, we describe several applications of CRISPR/Cas9 to stem cells related to degenerative diseases. In addition, we address the challenges and future perspectives regarding the use of CRISPR/Cas9 as an important technology in the medical sciences. 相似文献
69.
Zheng Li Jianqing Ma Jiaqi Bi Haiwei Guo Matthew T. V. Chan William K. K. Wu Zhanyong Wu Jianxiong Shen 《Journal of cellular physiology》2019,234(10):17896-17904
Air pollution exposure has been increasing extensively and there are evidence suggesting that exposure to air pollution during pregnancy can lead to congenital defects in the offspring. Recent findings suggested that microRNAs (miRNAs) might play important roles in the pathogenesis of developmental defects. However, the miRNAs profile pattern in the air pollution-exposed embryos remains unknown. RNA sequencing was performed to determine the differentially expressed miRNAs in the rat embryos (gestation day 9) with or without air pollution exposure. The potential functions and the associated mechanisms of these differentially expressed miRNAs were determined using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) analyses. The regulatory networks of mRNA–miRNA interactions were also reconstructed. As compared with the control group, a total of 291 miRNAs were differentially expressed in the rat embryos from the air pollution-exposed group, in which 204 and 87 miRNAs were significantly downregulated and upregulated, respectively. These miRNAs were predicted to deregulate mitotic spindle organization, cellular respiration, glycolate metabolism, and proteasome. Extensive regulation of target genes by miR-346, miR-504, miR-214-3p and miR-1224 was also predicted. Our results suggested that miRNAs may play crucial roles in the pathogenesis of air pollution-induced congenital spinal defects through deregulating multiple biological processes. 相似文献
70.