Spermidine/spermine-N1-acetyltransferase activity in isoprenaline-stimulated rat salivary glands

In parotid, sublingual and submaxillary glands stimulated by continuous intravenous infusion of isoprenaline at various doses for 3 h, the concentrations of the polyamines putrescine, spermidine, spermine and N1-acetylspermidine as well as the activities of ornithine decarboxylase and spermidine/spermine-N1-acetyltransferase were determined. Ornithine decarboxylase is the enzyme that catalyses the formation of putrescine from ornithine. The most striking effect was observed in parotid glands. Here, the beta-adrenergic agonist increased the activity of spermidine/spermine-N1-acetyltransferase markedly, but only slightly (if at all) that of ornithine decarboxylase. It also increased the concentrations of N1-acetylspermidine and putrescine markedly. The result obtained in this gland indicates interconversion of higher polyamines to putrescine.     

Optimal heparin surface concentration and antithrombin binding capacity as evaluated with human non-anticoagulated blood in vitro

Contact between blood and a biomaterial surface takes place in many applications and is known to activate the coagulation and complement systems. Heparin surface coatings have been shown to reduce blood activation upon contact with artificial surfaces. To establish the optimal heparin surface concentration, blood was incubated in a tubing loop model at 37 degrees C. The tubing was coated with different surface concentrations of heparin and rotated at three different velocities. We demonstrate that the blood compatibility of a surface with regard to coagulation, complement, and platelet activation can be improved by increasing the heparin surface concentration in the 6-12 pmol antithrombin/cm2 concentration interval. The binding of factor H is not influenced by the increased heparin surface concentration, suggesting that this factor is not the primary regulator of complement on heparin surfaces. In addition, the heparin coating has no effect on the complement activation that occurs on gas surfaces in extracorporeal circuits.     

Ovarian hormone effects on 5-hydroxytryptamine(2A) and 5-hydroxytryptamine(2C) receptor mRNA expression in the ventral hippocampus and frontal cortex of female rats

Alterations in female gonadal hormones are associated with anxiety and mood changes. The aim of the present study was to determine influences of chronic gonadal hormone supplementation on 5-HT(2A) and 5-HT(2C) receptor mRNA levels in the ventral hippocampus and the frontal cerebral cortex. Ovariectomized adult female Sprague-Dawley rats (n=37) received implantation of subcutaneous pellets containing different dosages of 17beta-estradiol alone or in combination with progesterone, or placebo pellets, for 2 weeks. Serotonin receptor mRNA levels were analyzed by in situ hybridization in the ventral hippocampus and 5-HT(2A) receptor mRNA also in the frontal cortex. Estradiol treatment in combination with low-dose progesterone increased 5-HT(2A) receptor mRNA by 43% in the CA2 region of the ventral hippocampus, while estradiol combined with high-dose progesterone increased the expression of this gene by 84% in ventral CA1. 5-HT(2A) mRNA expression in the frontal cortex was not influenced by hormone manipulation. 5-HT(2C) receptor gene expression was in the ventral hippocampus decreased in the CA2, ventral CA1 and the subiculum subregions by high-dose estradiol treatment (8-20% decreases). Effects on mood by gonadal hormones can be mediated, at least partly, through influences on 5-HT(2A) and 5-HT(2C) receptor expression.     

c-Myc is essential for vasculogenesis and angiogenesis during development and tumor progression

c-Myc promotes cell growth and transformation by ill-defined mechanisms. c-myc(-/-) mice die by embryonic day 10.5 (E10.5) with defects in growth and in cardiac and neural development. Here we report that the lethality of c-myc(-/-) embryos is also associated with profound defects in vasculogenesis and primitive erythropoiesis. Furthermore, c-myc(-/-) embryonic stem (ES) and yolk sac cells are compromised in their differentiative and growth potential. These defects are intrinsic to c-Myc, and are in part associated with a requirement for c-Myc for the expression of vascular endothelial growth factor (VEGF), as VEGF can partially rescue these defects. However, c-Myc is also required for the proper expression of other angiogenic factors in ES and yolk sac cells, including angiopoietin-2, and the angiogenic inhibitors thrombospondin-1 and angiopoietin-1. Finally, c-myc(-/-) ES cells are dramatically impaired in their ability to form tumors in immune-compromised mice, and the small tumors that sometimes develop are poorly vascularized. Therefore, c-Myc function is also necessary for the angiogenic switch that is indispensable for the progression and metastasis of tumors. These findings support the model wherein c-Myc promotes cell growth and transformation, as well as vascular and hematopoietic development, by functioning as a master regulator of angiogenic factors.     

DNA microarray technique for detection and identification of seven flaviviruses pathogenic for man

A flavivirus microarray was developed for detection and identification of yellow fever (YF), West Nile, Japanese encephalitis (JE), and the dengue 1-4 viruses, which are causing severe human disease all over the world. The microarray was based on 500-nucleotide probe fragments from five different parts of the seven viral genomes. A low-stringent amplification method targeting the corresponding regions of the viral genomic RNA was developed and combined with hybridization to the microarray for detection and identification. For distinction of the generated virus-specific fluorescence-patterns a fitting analysis procedure was adapted. The method was verified as functional for all seven flaviviruses and the strategy for the amplification, combined with the long probes, provided a high tolerance for smaller genetic variability, most suitable for these rapidly changing RNA viruses. A potentially high detection and identification capacity was proven on diverged strains of West Nile and dengue viruses. The lower limit for detection was equivalent, or better, when compared to routinely used RT-PCR methods. The performance of the method was verified on human patient samples containing dengue viruses, or normal human serum spiked with YF or JE viruses. The results demonstrated the ability of the flavivirus microarray to screen simultaneously a sample for several viruses in parallel, in combination with a good lower limit of detection.     

COMPLEXITY OF THE BOVINE MHC CLASS-II SPECIFICITY DW3 AS DEFINED BY ALLOANTISERA

Alloantisera related to the bovine major histocompatibility complex (MHC) class-II specificity Dw3 were investigated by cross-absorption experiments and by application of the monoclonal antibody-specific immobilization of lymphocyte antigen assay (MAILA). The absorption study revealed antibodies specific for an antigenic determinant shared by all Ds03 (Dw3)-positive animals, and several other antibody populations recognizing the locally defined specificites Ds10, Ds11 and Ds15, that are closely associated with Ds03. The results of the MAILA-assay indicate that the Ds03 specificity is probably encoded by DQ, whereas specificities Ds10 and Ds11 are more closely associated with DR molecules. The data presented here provide the first evidence that bovine DR and DQ specificities can be identified separately by serological methods using alloimmune antisera.     

Decreased inducibility of TNF expression in lipid-loaded macrophages

Background  

Inflammation and immune responses are considered to be very important in the pathogenesis of atherosclerosis. Lipid accumulation in macrophages of the arterial intima is a characteristic feature of atherosclerosis which can influence the inflammatory potential of macrophages. We studied the effects of lipid loading on the regulation of TNF expression in human monocyte-derived macrophages.     

Defense of the ansatz for dynamical hierarchies

Gross and McMullin [Artificial Life, 7, 355-365] criticize the conclusions of our article on dynamical hierarchies [Artificial Life, 7, 329-353]. In this note we respond to their criticisms. After clarifying our ansatz, we argue that the simulations presented by Gross and McMullin present no evidence against the ansatz, in part because their simulations use a different simulation framework, and in part because their simulations are no less complex than ours. We also clarify why the micelles in our simulations are third-order emergent structures, and why we emphasize realism in our simulation.     

Diffusive-convective mass transfer rates for solutes present on both sides of a dialyzer membrane

The transport (J) of waste products across dialyzer membranes is known to be proportional to the blood inlet concentration (Cbi) according to J = KCbi, where K is the clearance. For solutes present on both sides of the membrane, like sodium chloride, it has been shown that under certain conditions the transport rate will depend linearly also upon the dialysis fluid inlet concentration Cdi according to J = KbCbi -KdCdi. Kb and Kd are generalized clearances, which depend upon flow rates and membrane permeability but are independent of the concentrations. We have extended the results of Ross et al. in three ways. First, they only considered ultrafiltration (UF) that is equally distributed along the dialyzer. This is an unrealistic assumption, especially in hemodiafiltration and hemofiltration treatments with large UF rates (Quf) leading to large pressure drops along the dialyzer. Our approach allows for an arbitrary UF distribution. Second, it was possible to incorporate the more realistic model of Villaroel et al. for the local combination of diffusion and convection. Finally, we allow an arbitrary distribution of blood among the different fibers. All of these results are valid in both cocurrent and countercurrent configurations. With a sieving coefficient of 1, a good approximation for small solutes, we were also able to show that Kd = Kb - Quf, irrespective of the UF distribution along the dialyzer. This is an important result that, for example, provides a theoretical foundation for allowing a nonzero Quf in conductivity based clearance measurements.