四肢关节专用低场强MRI评估对膝关节损伤的诊断价值

目的：分析四肢关节专用低场强MRI诊断膝关节损伤的临床应用价值。 方法：于2004-12/2005-10解放军总医院全军骨科研究所收治经手术、关节镜检查或临床证实的膝关节损伤患者40例（43个膝关节）。应用Atorscan0.2T永磁型四肢关节专用低场强磁共振机,对膝关节损伤的MRI表现进行分析。 结果：四肢关节专用低场强MRI对半月板、前交叉韧带、骨挫伤等均可作出正确诊断。 结论：四肢关节专用低场强MRI对膝关节损伤的综合诊断具有重要意义,是膝关节损伤较理想的一种非创伤性检查方法。     

Local and systemic delivery of a stable aspirin-triggered lipoxin prevents neutrophil recruitment in vivo

Aspirin (ASA) triggers a switch in the biosynthesis of lipid mediators, inhibiting prostanoid production and initiating 15-epi-lipoxin generation through the acetylation of cyclooxygenase II. These aspirin-triggered lipoxins (ATL) may mediate some of ASA's beneficial actions and therefore are of interest in the search for novel antiinflammatories that could manifest fewer unwanted side effects. Here, we report that design modifications to native ATL structure prolong its biostability in vivo. In mouse whole blood, ATL analogs protected at carbon 15 [15(R/S)-methyl-lipoxin A4 (ATLa1)] and the omega end [15-epi-16-(para-fluoro)-phenoxy-LXA4 (ATLa2)] were recoverable to approximately 90 and 100% at 3 hr, respectively, compared with a approximately 40% loss of native lipoxin A4. ATLa2 retains bioactivity and, at levels as low as approximately 24 nmol/mouse, potently inhibited tumor necrosis factor-alpha-induced leukocyte recruitment into the dorsal air pouch. Inhibition was evident by either local intra-air pouch delivery (approximately 77% inhibition) or systemic delivery by intravenous injection (approximately 85% inhibition) and proved more potent than local delivery of ASA. Rank order for inhibiting polymorphonuclear leukocyte infiltration was: ATLa2 (10 micrograms, i.v.) approximately ATLa2 (10 micrograms, local) approximately dexamethasone (10 micrograms, local) >ASA (1.0 mg, local). Applied topically to mouse ear skin, ATLa2 also inhibited polymorphonuclear leukocyte infiltration induced by leukotriene B4 (approximately 78% inhibition) or phorbol ester (approximately 49% inhibition), which initiates endogenous chemokine production. These results indicate that this fluorinated analog of natural aspirin-triggered lipoxin A4 is bioavailable by either local or systemic delivery routes and is a more potent and precise inhibitor of neutrophil accumulation than is ASA.     

Construction of a highly enriched marsupial Y chromosome-specific BAC sub-library using isolated Y chromosomes

The Y chromosome is perhaps the most interesting element of the mammalian genome but comparative analysis of the Y chromosome has been impeded by the difficulty of assembling a shotgun sequence of the Y. BAC-based sequencing has been successful for the human and chimpanzee Y but is difficult to do efficiently for an atypical mammalian model species (Skaletsky et al. 2003, Kuroki et al. 2006). We show how Y-specific sub-libraries can be efficiently constructed using DNA amplified from microdissected or flow-sorted Y chromosomes. A Bacterial Artificial Chromosome (BAC) library was constructed from the model marsupial, the tammar wallaby (Macropus eugenii). We screened this library for Y chromosome-derived BAC clones using DNA from both a microdissected Y chromosome and a flow-sorted Y chromosome in order to create a Y chromosome-specific sub-library. We expected that the tammar wallaby Y chromosome should detect ∼100 clones from the 2.2 times redundant library. The microdissected Y DNA detected 85 clones, 82% of which mapped to the Y chromosome and the flow-sorted Y DNA detected 71 clones, 48% of which mapped to the Y chromosome. Overall, this represented a ∼330-fold enrichment for Y chromosome clones. This presents an ideal method for the creation of highly enriched chromosome-specific sub-libraries suitable for BAC-based sequencing of the Y chromosome of any mammalian species.     

Complex evolution of X and Y autosomal translocations in the giant mole-rat, Cryptomys mechowi (Bathyergidae)

Cross-species chromosome painting was used to determine homologous chromosomal regions between two species of mole-rat, the naked mole-rat, Heterocephalus glaber (2n = 60), and the giant mole-rat, Cryptomys mechowi (2n = 40), using flow-sorted painting probes representative of all but two of the H. glaber chromosomal complement. In total 43 homologous regions were identified in the C. mechowi genome. Eight H. glaber chromosomes are retained in toto in C. mechowi, and 13 produce two or more signals in this species. The most striking difference in the karyotypes of the two taxa concerns their sex chromosomes. The H. glaber painting probes identified a complex series of translocations that involved the fractionation of four autosomes and the subsequent translocation of segments to the sex chromosomes and to autosomal partners in the C. mechowi genome. An intercalary heterochromatic block (IHB) was detected in sex chromosomes of C. mechowi at the boundary with the translocated autosomal segment. We discuss the likely sequence of evolutionary events that has led to the contemporary composition of the C. mechowi sex chromosomes, and consider these in the light of prevailing views on the genesis of sex chromosomes in mammals.     

Secreted frizzled-related protein-4 reduces sodium–phosphate co-transporter abundance and activity in proximal tubule cells

The phosphatonin, secreted frizzled-related protein-4 (sFRP-4), induces phosphaturia and inhibits 25-hydroxyvitamin D 1-hydroxylase activity normally induced in response to hypophosphatemia. To determine the mechanism by which sFRP-4 alters renal phosphate (P_i) transport, we examined the effect of sFRP-4 on renal brush border membrane (BBMV) Na⁺-dependent P_i uptake, and the abundance and localization of the major Na⁺–P_i-IIa co-transporter in proximal tubules and opossum kidney (OK) cells. Infusion of sFRP-4 increased renal fractional excretion of P_i and decreased renal -catenin concentrations. The increase in renal P_i excretion with sFRP-4 infusion was associated with a 21.9±3.4% decrease in BBMV Na⁺-dependent P_i uptake (P<0.001) compared with a 39.5±2.1% inhibition of Na⁺-dependent P_i transport in renal BBMV induced by PTH (P<0.001). sFRP-4 infusion was associated with a 30.7±4.8% decrease in Na⁺–P_i-IIa co-transporter protein abundance (P<0.01) assessed by immunoblotting methods compared to a 45.4±8.8% decrease induced by PTH (P<0.001). In OK cells, sFRP-4 reduced surface expression of a heterologous Na⁺–P_i-IIa co-transporter. We conclude that sFRP-4 increases renal P_i excretion by reducing Na⁺–P_i-IIa transporter abundance in the brush border of the proximal tubule through enhanced internalization of the protein.     

Phylogenomics of the dog and fox family (Canidae,Carnivora) revealed by chromosome painting

Canid species (dogs and foxes) have highly rearranged karyotypes and thus represent a challenge for conventional comparative cytogenetic studies. Among them, the domestic dog is one of the best-mapped species in mammals, constituting an ideal reference genome for comparative genomic study. Here we report the results of genome-wide comparative mapping of dog chromosome-specific probes onto chromosomes of the dhole, fennec fox, and gray fox, as well as the mapping of red fox chromosome-specific probes onto chromosomes of the corsac fox. We also present an integrated comparative chromosome map between the species studied here and all canids studied previously. The integrated map demonstrates an extensive conservation of whole chromosome arms across different canid species. In addition, we have generated a comprehensive genome phylogeny for the Canidae on the basis of the chromosome rearrangements revealed by comparative painting. This genome phylogeny has provided new insights into the karyotypic relationships among the canids. Our results, together with published data, allow the formulation of a likely Canidae ancestral karyotype (CAK, 2n = 82), and reveal that at least 6–24 chromosomal fission/fusion events are needed to convert the CAK karyotype to that of the modern canids. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Comparative chromosome painting in Columbidae (Columbiformes) reinforces divergence in Passerea and Columbea

Pigeons and doves (Columbiformes) are one of the oldest and most diverse extant lineages of birds. However, the karyotype evolution within Columbiformes remains unclear. To delineate the synteny-conserved segments and karyotypic differences among four Columbidae species, we used chromosome painting from Gallus gallus (GGA, 2n?=?78) and Leucopternis albicollis (LAL, 2n?=?68). Besides that, a set of painting probes for the eared dove, Zenaida auriculata (ZAU, 2n?=?76), was generated from flow-sorted chromosomes. Chromosome painting with GGA and ZAU probes showed conservation of the first ten ancestral pairs in Z. auriculata, Columba livia, and Columbina picui, while in Leptotila verreauxi, fusion of the ancestral chromosomes 6 and 7 was observed. However, LAL probes revealed a complex reorganization of ancestral chromosome 1, involving paracentric and pericentric inversions. Because of the presence of similar intrachromosomal rearrangements in the chromosomes corresponding to GGA1q in the Columbidae and Passeriformes species but without a common origin, these results are consistent with the recent proposal of divergence within Neoaves (Passerea and Columbea). In addition, inversions in chromosome 2 were identified in C. picui and L. verreauxi. Thus, in four species of distinct genera of the Columbidae family, unique chromosomal rearrangements have occurred during karyotype evolution, confirming that despite conservation of the ancestral syntenic groups, these chromosomes have been modified by the occurrence of intrachromosomal rearrangements.     

Ticagrelor inhibits platelet–tumor cell interactions and metastasis in human and murine breast cancer

Activated platelets promote the proliferation and metastatic potential of cancer cells. Platelet activation is largely mediated through ADP engagement of purinergic P2Y12 receptors on platelets. We examined the potential of the reversible P2Y12 inhibitor ticagrelor, an agent used clinically to prevent cardiovascular and cerebrovascular events, to reduce tumor growth and metastasis. In vitro, MCF-7, MDA-MB-468, and MDA-MB-231 human mammary carcinoma cells exhibited decreased interaction with platelets treated with ticagrelor compared to untreated platelets. Prevention of tumor cell–platelet interactions through pretreatment of platelets with ticagrelor did not improve natural killer cell-mediated tumor cell killing of K562 myelogenous leukemia target cells. Additionally, ticagrelor had no effect on proliferation of 4T1 mouse mammary carcinoma cells co-cultured with platelets, or on primary 4T1 tumor growth. In an orthotopic 4T1 breast cancer model, ticagrelor (10 mg/kg), but not clopidogrel (10 mg/kg) or saline, resulted in reduced metastasis and improved survival. Ticagrelor treatment was associated with a marked reduction in tumor cell–platelet aggregates in the lungs at 10, 30 and 60 min post-intravenous inoculation. These findings suggest a role for P2Y12-mediated platelet activation in promoting metastasis, and provide support for the use of ticagrelor in the prevention of breast cancer spread.     

Controlled release of transforming growth factor-β3 from cartilage-extra-cellular-matrix-derived scaffolds to promote chondrogenesis of human-joint-tissue-derived stem cells

The objective of this study was to develop a scaffold derived from cartilaginous extracellular matrix (ECM) that could be used as a growth factor delivery system to promote chondrogenesis of stem cells. Dehydrothermal crosslinked scaffolds were fabricated using a slurry of homogenized porcine articular cartilage, which was then seeded with human infrapatellar-fat-pad-derived stem cells (FPSCs). It was found that these ECM-derived scaffolds promoted superior chondrogenesis of FPSCs when the constructs were additionally stimulated with transforming growth factor (TGF)-β3. Cell-mediated contraction of the scaffold was observed, which could be limited by the additional use of 1-ethyl-3-3dimethyl aminopropyl carbodiimide (EDAC) crosslinking without suppressing cartilage-specific matrix accumulation within the construct. To further validate the utility of the ECM-derived scaffold, we next compared its chondro-permissive properties to a biomimetic collagen–hyaluronic acid (HA) scaffold optimized for cartilage tissue engineering (TE) applications. The cartilage-ECM-derived scaffold supported at least comparable chondrogenesis to the collagen–HA scaffold, underwent less contraction and retained a greater proportion of synthesized sulfated glycosaminoglycans. Having developed a promising scaffold for TE, with superior chondrogenesis observed in the presence of exogenously supplied TGF-β3, the final phase of the study explored whether this scaffold could be used as a TGF-β3 delivery system to promote chondrogenesis of FPSCs. It was found that the majority of TGF-β3 that was loaded onto the scaffold was released in a controlled manner over the first 10 days of culture, with comparable long-term chondrogenesis observed in these TGF-β3-loaded constructs compared to scaffolds where the TGF-β3 was continuously added to the media. The results of this study support the use of cartilage-ECM-derived scaffolds as a growth factor delivery system for use in articular cartilage regeneration.     

Bleeding Disorders in Adolescents with Heavy Menstrual Bleeding: The Queensland Statewide Paediatric and Adolescent Gynaecology Service

Study Objective

Heavy menstrual bleeding (HMB) is a common gynecological complaint among young women with up to 40% having experienced HMB. Bleeding disorders are increasingly being recognized in adolescents and young adults with HMB. The aim of this study was to determine the prevalence of bleeding disorders in adolescents with HMB, among patients who presented to the Queensland Statewide Paediatric and Adolescent Gynaecology Service between July 2007 and July 2017.