Tenascin-C expression in human epidermal keratinocytes is regulated by inflammatory cytokines and a stress response pathway

Melanin pigments in lower vertebrates are often found in locations other than the skin, thus forming an extracutaneous pigmentary system of unknown function. The cellular and biochemical structure of this system is still poorly characterized. This paper deals with the ultrastructural and biochemical features of the melanogenic system of Xenopus laevis. Melanin containing cells were identified in the dorsal and ventral skin, and in the lung, spleen, liver and connective tissue surrounding blood vessels. The pigment cells in the skin and the lungs appeared to be typical melanocytes. The spleen contained isolated melanocyte-like cells, but most of the pigment cells present in this organ were associated with melanomacrophage centers. Conversely, the liver appeared devoid of melanocytes and only displayed melanomacrophage centers. Tyrosinase activity was found in all pigment-containing organs except the liver. All organs containing tyrosinase activity also displayed melanin formation potential from L-tyrosine. Therefore, tyrosine hydroxylase and melanin formation activities could be detected only in those organs containing typical melanocytes but not in locations such as the liver, where only melanomacrophages centers were found.     

Mice deficient for the secreted glycoprotein SPARC/osteonectin/BM40 develop normally but show severe age-onset cataract formation and disruption of the lens

SPARC (secreted protein acidic and rich in cysteine, also known as osteonectin/BM40) is a secreted Ca2+-binding glycoprotein that interacts with a range of extracellular matrix molecules, including collagen IV. It is widely expressed during embryogenesis, and in vitro studies have suggested roles in the regulation of cell adhesion and proliferation, and in the modulation of cytokine activity. In order to analyse the function of this protein in vivo, the endogenous Sparc locus was disrupted by homologous recombination in murine embryonic stem cells. SPARC-deficient mice (Sparctm1Cam) appear normal and fertile until around 6 months of age, when they develop severe eye pathology characterized by cataract formation and rupture of the lens capsule. The first sign of lens pathology occurs in the equatorial bow region where vacuoles gradually form within differentiating epithelial cells and fibre cells. The lens capsule, however, shows no qualitative changes in the major basal lamina proteins laminin, collagen IV, perlecan or entactin. These mice are an excellent resource for further studies on how SPARC affects cell behaviour in vivo.     

A lineal equation for the classification of progressive and hyperactive spermatozoa

Capacitation of spermatozoa, a complex sequence of events that render them able to fertilize the egg, is generally associated with a switch from lineal, progressive movement to a vigorous, non-progressive pattern characterized by starlike tracks, a process known as hyperactivation. Development of a method for the analysis of progressive and hyperactive tracks is thus important for the assessment of capacitation in biochemical, physiological and clinical studies. In this study, we have applied a two-step heuristic model to deduce a lineal equation that discriminates hyperactive from progressive spermatozoa. The kinetic parameters (curvilinear velocity (VCL), linearity (LIN), amplitude of lateral head displacement (ALH), straightness (STR), wobble (WOB), mean 'dance' (DAN) and velocity of the average path (VAP)) of ram spermatozoa were evaluated with a computerized motility analyzer, and classified one by one as progressive or hyperactive by the appearance of their tracks. In a first step, a discriminating plane was defined by minimizing the number of misclassified spermatozoa ('conflicting points'); then, the plane was adjusted by an iterative process to minimize the distance from conflicting points to it. The resulting plane showed a discriminating capacity of over 95% for both classes, higher than that achieved by setting a threshold value for the parameters taken separately or in group. When included in a standard semen analysis, application of the equation allowed a rapid assessment of the percentage of hyperactive spermatozoa. The method described, developed in ram spermatozoa, can be applied to different species for a variety of purposes.     

Preparation and properties of radioactive rhenium glass microspheres intended for in vivo radioembolization therapy

Cdc25 phosphatases activate the cell division kinases throughout the cell cycle. The 2.3 A structure of the human Cdc25A catalytic domain reveals a small alpha/beta domain with a fold unlike previously described phosphatase structures but identical to rhodanese, a sulfur-transfer protein. Only the active-site loop, containing the Cys-(X)5-Arg motif, shows similarity to the tyrosine phosphatases. In some crystals, the catalytic Cys-430 forms a disulfide bond with the invariant Cys-384, suggesting that Cdc25 may be self-inhibited during oxidative stress. Asp-383, previously proposed to be the general acid, instead serves a structural role, forming a conserved buried salt-bridge. We propose that Glu-431 may act as a general acid. Structure-based alignments suggest that the noncatalytic domain of the MAP kinase phosphatases will share this topology, as will ACR2, a eukaryotic arsenical resistance protein.     

The role of exportin-t in selective nuclear export of mature tRNAs

Exportin-t (Xpo-t) is a vertebrate nuclear export receptor for tRNAs that binds tRNA cooperatively with GTP-loaded Ran. Xpo-t antibodies are shown to efficiently block tRNA export from Xenopus oocyte nuclei suggesting that it is responsible for at least the majority of tRNA export in these cells. We examine the mechanism by which Xpo-t-RanGTP specifically exports mature tRNAs rather than other forms of nuclear RNA, including tRNA precursors. Chemical and enzymatic footprinting together with phosphate modification interference reveals an extensive interaction between the backbone of the TPsiC and acceptor arms of tRNAPhe and Xpo-t-RanGTP. Analysis of mutant or precursor tRNA forms demonstrates that, aside from these recognition elements, accurate 5' and 3' end-processing of tRNA affects Xpo-t-RanGTP interaction and nuclear export, while aminoacylation is not essential. Intron-containing, end-processed, pre-tRNAs can be bound by Xpo-t-RanGTP and are rapidly exported from the nucleus if Xpo-t is present in excess. These results suggest that at least two mechanisms are involved in discrimination of pre-tRNAs and mature tRNAs prior to nuclear export.     

Effect of high irradiance and iron on volatile odour compounds in the cyanobacterium Microcystis aeruginosa

The cyanobacterium, Microcystis aeruginosa was exposed to direct sunlight for 3, 6 or 9 h in media containing either low or high concentrations of iron, in order to determine any effects on the composition of volatile odour compounds (VOCs) released under photooxidative conditions. The most abundant VOCs detected included aliphatic hydrocarbons (C15-C21), naphthalene and the terpenoid compounds, beta-cyclocitral, and beta-ionone. Exposure to sunlight and low iron concentrations resulted in a decrease in beta-cyclocitral, beta-ionone, heptadecane and the total VOCs concentration after 9 h with respect to the control cultures. Six VOCs detected in the low iron cells were not detected in any of the high iron cells. However, those VOCs present in the high iron cells, in general, occurred at higher concentrations than the equivalent low iron cells after exposure to the sunlight conditions. Consequently, it was concluded that exposure to both high irradiance and high iron concentrations influenced the VOCs composition in cyanobacteria and this was interpreted to represent a cellular change during the photooxidation-promoting conditions.     

The validity of the Tritrac-R3D activity monitor for the assessment of physical activity: II. Temporal relationships among objective assessments

Today the organ donor operation in brain dead donors is mostly projected as multiple organ procurement (MOP). Not only the kidneys, but heart and liver or additionally lungs and pancreas are removed in MOP. A good synchronization between the collaborating transplantation groups (thoracic and abdominal surgeon, urologist) is essential to prevent loss of an organ because of technical problems. In Germany urologists perform more than 40% of kidney transplantations. These urologic institutions perform the cadaver kidney retrievals and participate on MOP. If possible, an urologist experienced in renal transplantation should contribute to the care for quality of the kidneys. Since 1987 the transplant center of Bremen obtained 390 donor registrations. 202 organ donor operations have been performed (106 MOP and 96 exclusive kidney retrievals). 398 donor kidneys have been collected and 382 could be transplanted.     

High-dose therapy including carboplatin adjusted for renal function in patients with relapsed or refractory germ cell tumour: outcome and prognostic factors

Thirty-one consecutive patients with relapsed or refractory GCT received an HDT schedule including carboplatin, the dose of which was adjusted to measured glomerular filtration rate. There was one HDT-associated death (3%), due to acute renal failure. The 3-year probability of overall and disease-free survival for 21 patients with primary refractory disease or responsive relapse was 60% and 42%, respectively, while none of ten patients with refractory relapse have survived disease free.     

Fabricating abutment crowns for existing removable partial dentures using custom resin clasp analogs

A universal approach for fabricating abutment crowns for existing removable partial dentures is described. A replica (analog) of the clasp assembly is generated and transferred to a traditional working cast, which includes the abutment die. The analog is incorporated into the working cast as a removable component to allow the formation of the crown contours. The article reviews in detail the procedures required to transfer accurately all the essential components and information from the mouth to the working cast while allowing the patient uninterrupted use of the removable partial denture. Prestabilizing the removable partial denture, creating the analog impression, avoiding errors due to soft tissue components, forming a precise analog base, selecting materials, generating a rigid resin analog, and prescribing a path of insertion and withdrawal to the analog are described. The method replicates all types of clasps and can generate all types of fixed prosthodontic retainers to function harmoniously with the existing partial denture.