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1.
The mitochondrial genome of Aspergillus nidulans contains several group-I introns. Each one has been assayed for its ability to self-splice in vitro in the absence of proteins.
The intron from the apocytochrome b gene is unusual among subgroup IB4 introns in being able to self-splice, unlike a similar
intron from Saccharomyces cerevisiae. The first intron in the cytochrome oxidase subunit-1 gene self-splices but only correctly completes the first step of splicing;
cryptic 3′ splice-sites are recognized instead and these are also used at a low frequency in vivo. The highly homologous intron
from Podospora anserina completes both steps in vitro. The remaining introns do not self-splice. The correlation between subgroup category, the likely
presence of specific tertiary interactions, and self-splicing activity is discussed.
Received: 16 May / 25 August 1997 相似文献
2.
黑柴胡中新三萜皂甙的结构鉴定 总被引:3,自引:0,他引:3
从黑柴胡(Bupleurum smithii Wolff)根中分离出10个化合物,均为首次由该植物中获得。其中二个新三萜皂甙,即柴胡皂甙k和l(saikosaponin k and l),其结构经紫外、红外、核磁共振氢谱,碳谱和质谱等波谱测定和解析,分别确定为3β,16β,23,28-四羟基齐墩果烷-11,13(18)-二烯-3-O-β-D-吡喃木糖基-(1→2)-β-D-吡喃葡萄糖基-(1→3)-β-D-吡喃呋糖甙和3β,16α,23,28,30-五羟基齐墩果烷-11,13(18)-二烯-3-O-β-D-吡喃葡萄糖基-(1→3)-β-D-吡喃呋糖甙。 相似文献
3.
Calcineurin B1 is essential for positive but not negative selection during thymocyte development 总被引:6,自引:0,他引:6
During development, discrete cell fates often result from variation in the intensity of a particular signal. The mechanisms underlying these seemingly analog-to-digital switches are not understood. In developing T lymphocytes, low-intensity signals through the antigen receptor result in positive selection while more intense signals give rise to negative selection. By deleting the genetic locus encoding the regulatory B1 subunit of calcineurin specifically in thymocytes, we found an absolute requirement for calcineurin in positive selection. In contrast, calcineurin activity was dispensable in several models of negative selection. Unexpectedly, we found that removal of calcineurin activity from thymocytes results in inefficient ERK activation at the double-positive stage of thymocyte development, when selection occurs. These studies clarify the mechanism by which graded signals are converted to discrete outcomes in T cell development and further indicate that the developmental roles of calcineurin likely contribute to immunosuppression by calcineurin inhibitors. 相似文献
4.
5.
Traditionally, radiology has been conceived as a support department providing patient scanning services to the other clinical
departments in a hospital. However, recent advancements in networking technology and related information systems such as picture
archiving and communication system (PACS) and radiology information system (RIS) provide new opportunities for inventing different
types of diagnostic imaging businesses such as teleradiology. In this article, we examined the business processes of currently
operating imaging centers and proposed a prototype of an information system that can facilitate their workflows in a more
efficient way. The principal component of our proposed system is a report management module built on extensible markup language
(XML) technologies that allows much flexibility and convenience for both imaging technicians and radiologists. 相似文献
6.
In this report, we describe the identification of a human leucocyte antigen-A*11 (HLA-A*11) nucleotide sequence variant, a new HLA-A*1120 by using sequence-based typing (SBT). The new allele was detected during routine HLA typing by high-resolution SBT. Allele A*1120 showed one nucleotide difference with A*110101 at codon 152 (GCG-->GAG) resulting in an amino acid change from alanine to glutamate. Residue 152 is located on alpha(2)-helix of HLA class I molecule and involved in peptide binding by constructing E pocket of peptide-binding groove, implying that the change of the residue 152 would affect the binding affinity of peptides to A*1120 allele. 相似文献
7.
Kim D Hur DY Kim YS Lee K Lee Y Cho D Kang JS Kim YI Hahm E Yang Y Yoon S Kim S Lee WB Park HY Kim YB Hwang YI Chang KY Lee WJ 《Human immunology》2002,63(7):576-587
Burkitt lymphoma (BL) is a tumor with the characteristics of germinal center B cells. We previously reported that the CM1 (centrocyte/-blast marker 1) molecule is expressed only in germinal center B cells, specifically, in a subpopulation of centroblasts and centrocytes. In the present study, we investigated the apoptosis induced by anti-CM1 in the Ramos and Raji human BL cell lines. The Ramos is protected from apoptosis by the crosslinking of sIgM and the calcium ionophore by the ligation of CD40 with anti-CD40 monoclonal antibodies (mAb) or soluble CD40 ligand (sCD40L). In this investigation on the effect of CM1 on apoptosis in BL cell lines, we found that cellular signaling by CM1 induces apoptosis and decreases cell viability, in BL cell lines cultured for 24 hours with protein-G agarose beads conjugated anti-CM1 mAb. Stimulation by CD40 ligated with sCD40L protected Raji cells from CM1-induced apoptosis, but did not protect Ramos cells. Furthermore, after anti-CM1 mAb stimulation, CD95 expression was upregulated and CD40 expression was unaltered or slightly decreased in Ramos cells, whereas CD95 was downregulated and CD40 was slightly upregulated in Raji cells. The engagement of CD40 by sCD40L enhanced CD95 expression, but the level of CM1 expression was unchanged in Ramos. However, sCD40L downregulated both CD95 and CM1 expression in Raji. In addition, the caspase-8 specific inhibitor blocked CM1-induced apoptosis in Ramos cells, but not in Raji cells. Increased mitochondrial membrane permeabilization was observed only in Raji cells. Moreover, the effector caspase inhibitor, z-DEVD, blocked CM1-mediated apoptosis in both cell lines. We found that CM1-induced apoptosis is achieved via different initiation pathways, which are cell-type dependent. 相似文献
8.
Yu Seong Hyeon Hur Young Hoe Hwang Eu Chang Kim Myung Soo Chung Ho Seok Lee Byung Chan Heo Suk Hee Choi Chan Hwang Jun Eul Bae Woo Kyun Jung Seung Il Kwon Dong Deuk 《International urology and nephrology》2021,53(1):69-75
International Urology and Nephrology - Multidetector computed tomographic urography (MDCTU) is not yet sufficient to be used in the clinical staging of upper tract urothelial carcinoma (UTUC). This... 相似文献
9.
BackgroundTertiary hyperparathyroidism associated with end-stage renal disease is characterized by progression from secondary hyperparathyroidism to an autonomous overproduction of parathyroid hormone that leads to adverse health outcomes. Rates of parathyroidectomy (PTX) have decreased with the use of calcimimetics. Optimal timing of PTX in relation to kidney transplant remains controversial. We aimed to identify the most cost-effective strategy for patients with tertiary hyperparathyroidism undergoing kidney transplant.MethodsWe constructed a patient level state transition microsimulation to compare 3 management schemes: cinacalcet with kidney transplant, cinacalcet with PTX before kidney transplant, or cinacalcet with PTX after kidney transplant. Our base case was a 55-year-old on dialysis with tertiary hyperparathyroidism awaiting kidney transplant. Outcomes, including quality-adjusted life years, surgical complications, and mortality, were extracted from the literature, and costs were estimated using Medicare reimbursement data.ResultsOur base case analysis demonstrated that cinacalcet with PTX before kidney transplant was dominant, with a lesser cost of $399,287 and greater quality-adjusted life years of 10.3 vs $497,813 for cinacalcet with PTX after kidney transplant (quality-adjusted life years 9.4) and $643,929 for cinacalcet with kidney transplant (quality-adjusted life years 7.4).ConclusionCinacalcet alone with kidney transplant is the least cost-effective strategy. Patients with end-stage renal disease-related tertiary hyperparathyroidism should be referred for PTX, and it is most cost-effective if performed prior to kidney transplant. 相似文献