Xwnt-11: a maternally expressed Xenopus wnt gene

We have isolated and characterized a novel Xenopus wnt gene, Xwnt-11, whose expression pattern and overexpression phenotype suggest that it may be important for dorsal-ventral axis formation. Xwnt-11 mRNA is present during oogenesis and embryonic development through swimming tadpole stages. Xwnt-11 mRNA is ubiquitous in early oocytes and is localized during mid-oogenesis. By late oocyte stages, Xwnt-11 mRNA is localized to the vegetal cortex, with some mRNA in the vegetal cytoplasm. After egg maturation, Xwnt-11 mRNA is released from the vegetal cortex and is found in the vegetal cytoplasm. This early pattern of Xwnt-11 mRNA localization is similar to another vegetally localized maternal mRNA, Vg1 (D. A. Melton (1987) Nature 328, 80–82). In the late blastula, Xwnt-11 mRNA is found at high levels in the dorsal marginal zone. As gastrulation proceeds, Xwnt-11 mRNA appears in the lateral and ventral marginal zone and, during tadpole stages, it is found in the somites and first branchial arch. Injection of Xwnt-11 mRNA into UV-ventralized embryos can substantially rescue the UV defect by inducing the formation of dorsal tissues. The rescued embryos develop somitic muscle and neural tube; however, they lack notochord and anterior head structures.

Xenopus axis formation: induction of goosecoid by injected Xwnt-8 and activin mRNAs

In this study, we compare the effects of three mRNAs-goosecoid, activin and Xwnt-8- that are able to induce partial or complete secondary axes when injected into Xenopus embryos. Xwnt-8 injection produces complete secondary axes including head structures whereas activin and goosecoid injection produce partial secondary axes at high frequency that lack head structures anterior to the auditory vesicle and often lack notochord. Xwnt-8 can activate goosecoid only in the deep marginal zone, i.e., in the region in which this organizer-specific homeobox gene is normally expressed on the dorsal side. Activin B mRNA, however, can turn on goosecoid in all regions of the embryo. We also tested the capacity of these gene products to restore axis formation in embryos in which the cortical rotation was blocked by UV irradiation. Whereas Xwnt-8 gives complete rescue of anterior structures, both goosecoid and activin give partial rescue. Rescued axes including hindbrain structures up to level of the auditory vesicle can be obtained at high frequency even in the absence of notochord structures. The possible functions of Wnt-like and activin-like signals and of the goosecoid homeobox gene, and their order of action in the formation of Spemann's organizer are discussed.

Metabolic stress induces a Wnt-dependent cancer stem cell-like state transition

Reciprocal interactions between cancer cells and the tumor microenvironment drive multiple clinically significant behaviors including dormancy, invasion, and metastasis as well as therapy resistance. These microenvironment-dependent phenotypes share typical characteristics with cancer stem cells (CSC). However, it is poorly understood how metabolic stress in the confined tumor microenvironment contributes to the emergence and maintenance of CSC-like phenotypes. Here, we demonstrate that chronic metabolic stress (CMS) in a long-term nutrient deprivation induces a Wnt-dependent phenoconversion of non-stem cancer cells toward stem-like state and this is reflected in the transcriptome analysis. Addition of Wnt3a as well as transfection of dominant-negative Tcf4 establishes an obligatory role for the Wnt pathway in the acquisition of CSC-like characteristics in response to metabolic stress. Furthermore, systematic characterization for multiple single cell-derived clones and negative enrichment of CD44+/ESA+ stem-like cancer cells, all of which recapitulate stem-like cancer characteristics, suggest stochastic adaptation rather than selection of pre-existing subclones. Finally, CMS in the tumor microenvironment can drive a CSC-like phenoconversion of non-stem cancer cells through stochastic state transition dependent on the Wnt pathway. These findings contribute to an understanding of the metabolic stress-driven dynamic transition of non-stem cancer cells to a stem-like state in the tumor metabolic microenvironment.

Developmentally regulated excision of a 28-base-pair sequence from the Paramecium genome requires flanking DNA

The micronuclear DNA of Paramecium tetraurelia is estimated to contain over 50,000 short DNA elements that are precisely removed during the formation of the transcriptionally active macronucleus. Each internal eliminated sequence (IES) is bounded by 5'-TA-3' dinucleotide repeats, a feature common to some classes of DNA transposons. We have developed an in vivo assay to analyze these highly efficient and precise DNA excision events. The microinjection of a cloned IES into mating cells results in accurately spliced products, and the transformed cells maintain the injected DNA as extrachromosomal molecules. A series of deletions flanking one side of a 28-bp IES were constructed and analyzed with the in vivo assay. Whereas 72 bp of DNA flanking the eliminated region is sufficient for excision, lengths of 31 and 18 bp result in reduced excision and removal of all wild-type sequences adjacent to the TA results in complete failure of excision. In contrast, nucleotide mutations within the middle of the 28-bp IES do not prevent excision. The results are consistent with a functional role for perfect inverted repeats flanking the IES.

The bovine pericardial xenograft: III. Effect of uniaxial and sequential biaxial stress during fixation on the tensile viscoelastic properties of bovine pericardium

Our previous two articles have shown that glutaraldehyde-fixed bovine pericardium is nearly isotropic, whether fixed without constraints, with tethering, or with pressure. In this study, we have used uniaxial stress during fixation to produce bovine pericardial material with marked tensile anisotropy. Rectangular and cruciate pericardial samples have been mechanically examined after one of four treatments: (i) fixation under 88-kPa uniaxial stress, (ii) fixation under 176-kPa uniaxial stress, (iii) 3 h of 176-kPa uniaxial stress in saline followed by 24-h fixation under the same stress, (iv) fixation under 176-kPa uniaxial stress followed by a second fixation under 176-kPa stress in a direction normal to the first. Strips of material were cut at 0 degree, 30 degrees, 60 degrees, and 90 degrees to direction of the initial stress, and tested for response to cyclic loading, stress relaxation, plastic deformation, and fracture properties. Fixation under uniaxial stress produced anistropy similar to that seen in porcine aortic valve leaflets; however, the overall extensibility of the material depended on the applied stress and the aspect ratio of the stressed sample. While loading in saline produced no change, the sequential biaxial stressing produced a reduction in anisotropy, suggesting exposure of additional crosslinking sites. Uniaxial stress during fixation may be a useful method for construction of anisotropic heart valve leaflets.

Diffuse large B-cell lymphoma: A consensus practice statement from the Australasian Lymphoma Alliance

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma subtype, accounting for 30-40% of lymphoma diagnoses. Though aggressive, cure is achievable in approximately 60% of cases with primary chemo-immunotherapy, and in a further substantial minority by salvage therapy and autologous stem cell transplantation. Despite promising activity in early phase clinical trials, no intensified or novel treatment regimen has improved outcomes over R-CHOP21 in randomised studies. However, there remain several areas of controversy including the most appropriate prognostic markers, CNS prophylaxis and the optimal treatment for patients with high-risk disease. This position statement presents an evidence-based synthesis of the literature for application in Australasian practice. This article is protected by copyright. All rights reserved.

Association between endometriosis and risk of systemic lupus erythematosus

To examine the association between endometriosis and the risk of systemic lupus erythematosus (SLE), this nationwide, population-based, retrospective cohort study was conducted based on National Health Insurance Research Database in Taiwan. Endometriosis (N = 16,758) and non-endometriosis (N = 16,758) groups were identified by matching baseline characteristics and comorbidities. Student's t-tests and the Kaplan-Meier estimator were utilized to estimate the hazard ratio (HR) and cumulative probability of SLE in the two groups. The endometriosis group showed a significantly higher incidence density rate (0.3 vs. 0.1 per 1000 person-years) and hazard ratio in SLE group (adjusted HR [aHR], 2.37; 95% confidence interval [CI] 1.35-4.14) compared to the non-endometriosis group. Subgroup analysis revealed that patients with endometriosis between 30 and 45 years of age, or were non-steroidal anti-inflammatory drug users, or were hormonal medications-free participants, had higher risks of SLE. For patients with endometriosis, surgical intervention did not significantly impact on the risk of SLE. Our results demonstrated an increased risk of SLE in patients with endometriosis. Clinicians should be aware of this association when managing patients with endometriosis or SLE.

Diagnosis and management of primary central nervous system lymphoma: a Consensus Practice Statement from the Australasian Lymphoma Alliance

Primary central nervous system lymphoma is a clinicopathological disease entity that accounts for 1 % of all non-Hodgkin lymphoma (NHL). Advanced patient age, adverse disease biology and complexities of diagnosis and treatment render outcomes markedly inferior to systemic NHL. Despite this, an increasing evidence base including limited randomised controlled clinical trial data is informing optimal therapeutic strategies with methotrexate-based induction chemotherapy schedules and intensified consolidation in selected patients. This practice statement represents an evidence-based review of the literature and has been devised to assist healthcare professionals in the diagnosis and management of this disease. This article is protected by copyright. All rights reserved.

Improved Mechanical and Corrosion Properties of Powder Metallurgy Austenitic, Ferritic, and Martensitic Stainless Steels by Liquid Phase Sintering

Powder metallurgy (PM) has been widely used to produce various steels in industry, mainly due to its capabilities for manufacturing nearly net-shaped products and mass production. To improve the performances of PM stainless steels, the roles of 0.6 wt% B additive in the microstructures, mechanical properties, and corrosion resistances of PM 304L austenitic, 410L ferritic, and 410 martensitic stainless steels were investigated. The results showed that adding 0.6 wt% B significantly improved the sintered densities of the three kinds of stainless steels due to the liquid phase sintering (LPS) phenomenon. The borides in 304L + 0.6B, 410L + 0.6B, and 410 + 0.6B were rich in B and Cr atoms but deficient in Fe, Ni, or C atoms, as analyzed by electron probe micro-analysis. Furthermore, the B additive contributed to the improved apparent hardness and corrosion resistance of PM stainless steels. In the 410L stainless steel, the 0.6 wt% B addition increased the corrosion voltage from -0.43 V_SCE to -0.24 V_SCE and reduced the corrosion current density from 2.27 × 10^-6 A/cm² to 1.93 × 10^-7 A/cm². The effects of several factors, namely: porosity; the generation of boride; the matrix/boride interfacial areas; Cr depletion; and the microstructure on the corrosion performances are discussed. The findings clearly indicate that porosity plays a predominant role in the corrosion resistances of PM austenitic, ferritic, and martensitic stainless steels.

The Effects of Heat Treatment on the Impact Toughness and Fracture of Selective Laser-Melted Corrax Maraging Stainless Steel

In additive manufacturing (AM) metallic materials, heat treatment (HT) is a common process for modifying the unstable and anisotropic microstructure. Selective laser melting (SLM) Corrax maraging stainless steel is a novel material that has been applied in mold materials with conformal cooling channels in industry. However, the influences of HTs on the various mechanical properties of SLM Corrax steels are still not fully clarified. The aim of this research was thus to clarify the effects of solution treatment (S) and integrated solution-aging treatment (SA) on the hardness and impact toughness of SLM Corrax maraging stainless steel. Furthermore, to identify the roles of building direction (BD) on the hardness and impact toughness, parallelly built (P) and vertically built (V) SLM Corrax steels were fabricated and compared. The microstructures were examined by X-ray diffraction, electron backscatter diffraction, and electron probe micro-analysis, and to observe the fracture surface, scanning electron microscopy was used. The results showed that both the impact energies and apparent hardnesses were dominated by the HT. S treatment simultaneously decreased the impact energies and apparent hardnesses. SA treatment increased the apparent hardnesses but decreased the impact energies. BD did not apparently affect either the hardness or the toughness. Furthermore, the percentage of austenite did not affect the impact energies of the various material conditions. In the SA condition, the apparent hardnesses of P and V specimens were 49.9 HRC and 49.3 HRC, respectively. The impact energies of SA-P and SA-V specimens were 20 J and 17 J, respectively. The low anisotropy of SA specimens in hardness and toughness can be attributed to the weak texture and is advantageous to the material's stability during service.

Embrittlement Due to Excess Heat Input into Friction Stir Processed 7075 Alloy

The grain size of high strength 7075 hot-rolled aluminum plates was refined by a friction stir process (FSP) to improve their mechanical properties. The results of the tensile ductility tests, which were conducted at various tool rotational speeds, in the friction stir zone indicate significant tensile ductility loss, which even resulted in a ductile-to-brittle transition (DBT). DBT depends on the tool rotational speed. Our 1450 rpm specimens showed large data fluctuation in the tensile ductility and the location of the fracture controlled the formation of friction stir induced bands (FSIB). The crack initiation site located at FSIB was due to the tool rotational speed (1670 rpm). A higher heat-input causes the formation of FSIB, which is accompanied with micro-voids. This contributes significantly to tensile cracking within the stir zone after the application of the aging treatment. This investigation aimed to determine the dominant factor causing tensile ductility loss at the stir zone, which is the major restriction preventing further applications.