The Detection of Hamster Connexins: A Comparison of Expression Profiles with Wild-Type Mouse and the Cancer-Prone Min Mouse

The open reading frames of 17 connexins from Syrian hamster (using tissues) and 16 connexins from the Chinese hamster cell line V79, were fully (Cx30, Cx31, Cx37, Cx43 and Cx45) or partially sequenced. We have also detected, and partially sequenced, seven rat connexins that previously were unavailable. The expression of connexin genes was examined in some hamster organs and cultured hamster cells, and compared with wild-type mouse and the cancer-prone Min mouse. Although the expression patterns were similar for most organs and connexins in hamster and mouse, there were also some prominent differences (Cx29 and 30.3 in testis; Cx31.1 and 32 in eye; Cx46 in brain, kidney and testis; Cx47 in kidney). This suggests that some connexins have species-specific expression profiles. In contrast, there were minimal differences in expression profiles between wild type and Min mice. Species-specific expression profiles should be considered in attempts to make animal models of human connexin-associated diseases.     

Protein binding and stability of norepinephrine in human blood plasma. Involvement of prealbumin, alpha 1-acid glycoprotein and albumin

The binding of norepinephrine (NE) to plasma proteins of fresh human blood obtained from healthy volunteers was studied by ultrafiltration at different NE concentrations and incubation times at 37 degrees C. At 1.7 nM L-[3H]-NE binding was approximately 25%. The binding was rapid and was not influenced by the incubation time. [3H]-NE could be dissociated from its binding sites by acid precipitation and, after HPLC, showed to be unchanged NE. No difference in NE binding was found between plasma collected in EGTA-GSH or heparin solution. There was no degradation of NE when incubated in plasma at 37 degrees C for 10 h, even without the addition of antioxidants. Therefore, in the present study, binding represented interaction of unchanged NE with plasma proteins. The whole plasma binding was saturable over the range of 0.66 nM to 0.59 mM of NE. Scatchard plot of specific binding revealed high-affinity sites with a Kd of 5.4 nM and a Bmax of 3.9 fmoles.mg-1 protein, and low-affinity sites with a Kd of 2.7 microM and a Bmax of 3.3 pmoles.mg-1 protein. Electrophoretic characterization of NE-binding proteins showed that about 60% of bound NE was associated to albumin, and 20% to prealbumin. NE binding to pure human plasma proteins was also studied using ultrafiltration. Scatchard analyses revealed a single class of very high-affinity binding sites for prealbumin (Kd 4.9 nM), a single class of binding sites for alpha 1-acid glycoprotein (Kd 54 microM) and two classes of binding sites for albumin with high (Kd 1.7 microM) and low (Kd 0.8 mM) affinities respectively. The main results obtained in this study - a) reversibility of NE binding, b) stability of free and bound NE in plasma, c) involvement of the prealbumin as a specific binding protein - point out to a specific transport for NE in human blood plasma.     

Accumulation of the labdane diterpene Marrubiin in glandular trichome cells along the ontogeny of Marrubium vulgare plants

The content of the diterpene Marrubiin was assessed by GC-FID in leaves of Marrubium vulgare plants along their ontogeny. Maximum accumulation occurred just before flowering time and in fully expanded leaves. After feeding the plants with radio labeled [³H]-geranyl geranyl diphosphate, up to 70% of the radioactivity was recovered in HPLC-Rt coincidental with authentic Marrubiin, which was also characterized by GC-EIMS, thus confirming that the biosynthesis of Marrubiin proceeds through the 1-deoxy-D-xylulose-5-phosphate pathway. The major accumulation of radioactivity occurred in glandular trichome cells, and the product remained stable throughout.     

The metalloproteinase ADAM‐12 regulates bronchial epithelial cell proliferation and apoptosis

Abstract. Objectives: The ADAMs (a disintegrin and metalloproteinase) enzymes compose a family of membrane‐bound proteins characterized by their multi‐domain structure and ADAM‐12 expression is elevated in human non‐small cell lung cancers. The aim of this study was to investigate the roles played by ADAM‐12 in critical steps of bronchial cell transformation during carcinogenesis. Materials and methods: To assess the role of ADAM‐12 in tumorigenicity, BEAS‐2B cells were transfected with a plasmid encoding human full‐length ADAM‐12 cDNA, and then the effects of ADAM‐12 overexpression on cell behaviour were explored. Treatment of clones with heparin‐binding epidermal growth factor (EGF)‐like growth factor (HB‐EGF) neutralizing antibodies as well as an EGFR inhibitor allowed the dissection of mechanisms regulating cell proliferation and apoptosis. Results: Overexpression of ADAM‐12 in BEAS‐2B cells promoted cell proliferation. ADAM‐12 overexpressing clones produced higher quantities of HB‐EGF in their culture medium which may rely on membrane‐bound HB‐EGF shedding by ADAM‐12. Targeting HB‐EGF activity with a neutralizing antibody abrogated enhanced cell proliferation in the ADAM‐12 overexpressing clones. In sharp contrast, targeting of amphiregulin, EGF or transforming growth factor‐α failed to influence cell proliferation; moreover, ADAM‐12 transfectants were resistant to etoposide‐induced apoptosis and the use of a neutralizing antibody against HB‐EGF activity restored rates of apoptosis to be similar to controls.Conclusions: ADAM‐12 contributes to enhancing HB‐EGF shedding from plasma membranes leading to increased cell proliferation and reduced apoptosis in this bronchial epithelial cell line.     

The formation of a test system for assessing the safety of different types of pertussis preparations: their cytotoxic action on mouse thymocytes in vitro

The test for the evaluation of the toxicity of different types of pertussis preparations as manifested by their in vitro influence on mouse thymic cells (T test) has been finally worked out. The use of the T test has made it possible to reveal the nonstandard character of the production lots of adsorbed diphtheria-pertussis-tetanus vaccines, both whole-cell vaccine and Japanese acellular vaccine. The degree of the in vitro damaging action of pertussis preparations on mouse thymic cells greatly depends on the residual content of Bordetella pertussis nontoxoidized toxin which, in contrast to B. pertussis lipopolysaccharide and filamentous hemagglutinin, produces pronounced cytotoxic action on mouse thymic cells.     

Genotype-specific interactions and the trade-off between host and parasite fitness

Background  

Evolution of parasite traits is inextricably linked to their hosts. For instance one common definition of parasite virulence is the reduction in host fitness due to infection. Thus, traits of infection must be viewed in both protagonists and may be under shared genetic and physiological control. We investigated these questions on the oomycete Hyaloperonospora arabidopsis (= parasitica), a natural pathogen of the Brassicaceae Arabidopsis thaliana.     

Stress-Reactivity of Lungs according to Metabolic Function Parameters at Different Stages of Postnatal Ontogenesis

Analysis of parameters of metabolic function of lungs with respect to lipid metabolism was performed in rats under conditions of acute experimental emotional-nociceptive stress. Study of the stress-sensitivity of lungs in the comparative-age aspect has shown different extent of changes of several parameters of lipid metabolism in pulmonary tissue in animals of different age. The results of the study demonstrate areactivity and high stress-stability of lungs with respect to surface-active properties, free-radical processes, and lipase activity in early postnatal ontogenesis.     

Inactivation of the postural asymmetry factor at the stage of compensation for the postural disorder induced by unilateral removal of the motor area

The peptide nature of the posture asymmetry factor (PAF) produced in the brain after unilateral removal of the motor region of the neocortex was established. The inactivation of PAF activity in the brain toward the end of the third week after the removal is due to PAF inactivation by the endogenous factor absent from the intact brain. The molecular weight of the inactivation factor exceeds 5.0 kD that makes it possible to separate it from the PAF by gel filtration on Sephadex G-25. The correlation was marked between the increasing activity of the PAF inactivation factor and the recovery of the initial symmetric functioning of the spinal centers during three weeks after unilateral damage to the CNS.