Analysis of Dishevelled signalling pathways during Xenopus development

BACKGROUND: Recent studies have demonstrated that the Wnt, Frizzled and Notch proteins are involved in a variety of developmental processes in fly, worm, frog and mouse embryos. The Dishevelled (Dsh) protein is required for Drosophila cells to respond to Wingless, Notch and Frizzled signals, but the molecular mechanisms of its action are not well understood. Using the ability of a mutant form of the Xenopus homologue of Dsh (Xdsh) to block Wnt and Dsh signalling in a model system, this work attempts to clarify the role of the endogenous Xdsh during the early stages of vertebrate development. RESULTS: A mutant Xdsh (Xdd1) with an internal deletion of the conserved PDZ/DHR domain was constructed. Overexpression of Xdd1 mRNA in ventral blastomeres of Xenopus embryos strongly inhibited induction of secondary axes by the wild-type Xdsh and Xwnt8 mRNAs, but did not affect the axis-inducing ability of beta-catenin mRNA. These observations suggest that Xdd1 acts as a dominant-negative mutant. Dorsal expression of Xdd1 caused severe posterior truncations in the injected embryos, whereas wild-type Xdsh suppressed this phenotype. Xdd1 blocked convergent extension movements in ectodermal explants stimulated with mesoderm-inducing factors and in dorsal marginal zone explants, but did not affect mesoderm induction and differentiation. CONCLUSIONS: A vertebrate homologue of Dsh is a necessary component of Wnt signal transduction and functions upstream of beta-catenin. These findings also establish a requirement for the PDZ domain in signal transduction by Xdsh, and suggest that endogenous Xdsh controls morphogenetic movements in the embryo.     

Inhibitory effects of Hoe 140 on vasodilator responses to bradykinin in the mesenteric vascular bed of the cat

The effect of Hoe 140, a bradykinin B2 receptor antagonist, on vasodilator responses to bradykinin was investigated in the mesenteric vascular bed of the cat under constant flow conditions. Injections of bradykinin into the mesenteric vascular bed induced dose-related decreases in perfusion pressure which were reduced significantly following administration of Hoe 140 (D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]bradykinin) (100 micrograms/kg i.v.). The inhibitory effects of Hoe 140 were longer than 3 h in duration and vasodilator response to acetylcholine and S-nitroso-N-acetylpenicillamine and vasoconstrictor responses to norepinephrine, angiotensin II, and the thromboxane mimic, U46619 (9,11-dideoxy-11 alpha,9 alpha-epoxymethano-prostaglandin F2 alpha) were unchanged by the B2 receptor antagonist. Hoe 140 had little effect on baseline systemic arterial and mesenteric arterial perfusion pressures. These results suggest that Hoe 140 is a potent, highly selective, long-acting bradykinin B2 receptor antagonist with little agonistic activity in the mesenteric vascular bed of the cat.     

Structure and mechanical properties of a thermal-sprayed nickle-20wt.%chromium alloy

Powder of a nickel-chromium alloy (about 20 wt.% chromium) was low pressure plasma sprayed onto substrates which were cooled to various extents. As the maximum temperature of the sprayed deposit was increased up to approximately 1148–1235 K during spraying, the strength of the deposit, measured on tensile test pieces machined from the deposit, increased owing to the combined effects of precipitation strengthening and enhancement of adhesion between the flattened particles composing the deposit. It is proposed that an adequate rise in temperature of the deposit during spraying improves its strength more effectively than annealing a deposit held at low temperatures during spraying, as long as the heating temperature and the heating time of these two deposits are similar to each other.     

Multiple genotypes of mitochondrial DNA within a horse population from a small region in Yunnan Province of China

mtDNA genotypes of six domestic horses (three adult short horses whose heights are under 1 m and three common domestic horses) from a small region of 15 km2 in Malipo county of Yunnan province of China were investigated by the technique of restriction fragment length polymorphism (RFLP) with 16 restriction endonucleases which recognize 6-bp sequences. An average of 56 fragments for an individual was obtained. Unlike other domestic animals, this population of horses exhibits high mtDNA genetic diversity. Each of the six horses has a specific mtDNA genotype showing a pattern of multiple maternal origins, as suggested by fossil and literature records. We think the population of horses is an amazing seed-resource pool of horses and hence deserves to be paid more attention from the view of conservation genetics. However, it is also remarkable that we did not find any typical mtDNA genetic markers which would discriminate between short horses and common domestic horses.     

Optimal method of urgent decompression of the collecting system for obstruction and infection due to ureteral calculi

PURPOSE: We compare the efficacy of percutaneous nephrostomy with retrograde ureteral catheterization for renal drainage in cases of obstruction and infection associated with ureteral calculi. MATERIALS AND METHODS: We randomized 42 consecutive patients presenting with obstructing ureteral calculi and clinical signs of infection (temperature greater than 38 C and/or white blood count greater than 17,000/mm.3) to drainage with percutaneous nephrostomy or retrograde ureteral catheterization. Preoperative patient and stone characteristics, procedural parameters, clinical outcomes and costs were assessed for each group. RESULTS: Urine cultures obtained at drainage were positive in 62.9% of percutaneous nephrostomy and 19.1% of retrograde ureteral catheterization patients. There was no significant difference in the time to treatment between the 2 groups. Procedural and fluoroscopy times were significantly shorter in the retrograde ureteral catheterization (32.7 and 5.1 minutes, respectively) compared with the percutaneous nephrostomy (49.2 and 7.7 minutes, respectively) group. One treatment failure occurred in the percutaneous nephrostomy group, which was successfully salvaged with retrograde ureteral catheterization. Time to normal temperature was 2.3 days in the percutaneous nephrostomy and 2.6 in the retrograde ureteral catheterization group, and time to normal white blood count was 2 days in the percutaneous nephrostomy and 1.7 days in the retrograde ureteral catheterization group (p not significant). Length of stay was 4.5 days in the percutaneous nephrostomy group compared with 3.2 days in the retrograde ureteral catheterization group (p not significant). Cost analysis revealed that retrograde ureteral catheterization was twice as costly as percutaneous nephrostomy. CONCLUSIONS: Retrograde ureteral catheterization and percutaneous nephrostomy effectively relieve obstruction and infection due to ureteral calculi. Neither modality demonstrated superiority in promoting a more rapid recovery after drainage. Percutaneous nephrostomy is less costly than retrograde ureteral catheterization. The decision of which mode of drainage to use may be based on logistical factors, surgeon preference and stone characteristics.     

Thiol-linked peroxidase activity of human ceruloplasmin

Human ceruloplasmin exhibited different antioxidant effects according to the electron donors in a metal-catalyzed oxidation system. Purified ceruloplasmin did not play a significant role in the protection of DNA strand breaks in the ascorbate/Fe3+/O2 system. However, when ascorbates were replaced with a thiol-reducing equivalent such as dithiothreitol, DNA strand breaks were significantly prevented by the same amount of ceruloplasmin. Ceruloplasmin did not catalyze the decomposition of H2O2 in the absence of reduced glutathione. On the contrary, ceruloplasmin showed a potent peroxidase ability to destroy H2O2 in the presence of reduced glutathione. In conclusion, the removal of H2O2 by human ceruloplasmin is not simply stoichiometric but thiol-dependent.     

Some improvements in the phase contrast microscope

Some considerations on the improvement of the image quality of the phase contrast microscope are presented. The significance of glare and image fidelity discussed theoretically and the dependence of image fidelity and contrast on the phase plate characteristics are investigated on the basis of images calculated for different parameters of the annular phase plate. This paper also describes an anti-reflection technique for the phase plate and demonstrates its effectiveness in the elimination of glare.     

Molecular cloning of the rat adipocyte hormone-sensitive cyclic GMP-inhibited cyclic nucleotide phosphodiesterase

Two distinct but related cGMP-inhibited cyclic nucleotide phosphodiesterase (cGI PDE) cDNAs were cloned from rat adipose tissue cDNA libraries. The open reading frame (3324 base pairs) of RcGIP1 encodes 1108 amino acids, including a hydrophobic membrane-associated domain in the NH2-terminal portion and, in the COOH-terminal portion, a putative catalytic domain conserved among all mammalian PDEs which is preceded by a putative regulatory domain that contains three consensus cAMP-dependent protein kinase phosphorylation sites and followed by a hydrophilic COOH-terminal domain. The carboxyl-terminal portion including the conserved domain was expressed as a glutathione S-transferase fusion protein and exhibited cAMP PDE activity which was inhibited by cilostamide, a specific cGI PDE inhibitor. RcGIP1 cDNA hybridizes strongly with RNA from isolated adipocytes, and its mRNA increases dramatically during differentiation of 3T3-L1 adipocytes. The deduced sequence of the second partial cDNA clone (RcGIP2 clone 53B) is highly homologous to the corresponding region of human cardiac cGI PDE cDNA. RcGIP2 cDNA hybridized strongly with rat cardiac tissue RNA and weakly if at all with RNA from rat adipocytes or 3T3-L1 fibroblasts or adipocytes. We suggest that RcGIP1 represents the hormone-sensitive, membrane-associated rat adipocyte cGI PDE and RcGIP2, a cGI PDE from vascular elements in rat adipose tissue.     

Comparison of thermophilic anaerobic digestion characteristics between single-phase and two-phase systems for kitchen garbage treatment

Lab-scale single-phase and two-phase thermophilic methane fermentation systems (SPS and TPS, respectively) were operated and fed with artificial kitchen waste. In both SPS and TPS, the highest methane recovery ratio of 90%, in terms of chemical oxygen demand by dichromate (CODcr), was observed at an organic loading rate (OLR) of 15 gCODcr/(l.d). The ratio of particle CODcr remaining to total CODcr in the influent was 0.1 and the ratio of NH(4)-N concentration to the input total nitrogen concentration was 0.5 in both SPS and TPS. However, the propionate concentration in the SPS reactor fluctuated largely and was 2 gCODcr/l higher than that in TPS, indicating less stable digestion. Regardless, efficient kitchen waste degradation can be accomplished in both SPS and TPS at an OLR of <20 gCODcr/(l.d), even though TPS may be more stable and easier to maintain. Bacillus coagulans predominated with an occupied ratio of approximately 90% in the acid fermentation reactor of TPS, and then a richer microbial community with a higher Shannon index value was maintained in the methane fermentation reactor of TPS than in the SPS reactor.