Inhibition of MAP kinase activity moderates changes in expression and function of Cx32 but not claudin-1 during DNA synthesis in primary cultures of rat hepatocytes

The signal transduction pathways and activation of the MAP kinase or PI3 kinase signaling cascade regulate a variety of cellular processes, including proliferation and differentiation in hepatocytes. To elucidate the mechanisms of signal transmission required for the regulation of gap and tight junctions during DNA synthesis in rat hepatocytes, we determined changes of expression and function of gap and tight junctions of cells grown in primary culture, using inhibitors of signaling pathways for MAP kinase (PD98059) and PI3 kinase (LY294002). During the stimulation of DNA synthesis induced by epidermal growth factor (EGF), immunoreactivity and mRNAs of gap junction protein Cx32 and of tight junction protein claudin-1 markedly decreased with reduction of gap junctional intercellular communication (GJIC) and the fence function of tight junctions. In Western blots, whole-cell lysate of claudin-1 protein decreased and phosphorylated Cx32 protein in the insoluble fraction of Triton X-100 increased during the stimulation of DNA synthesis. During reinhibition of DNA synthesis, the changes of Cx32 and claudin-1 returned to control levels, as did both functions. In treatment with the inhibitors before DNA synthesis, PD98059 inhibited the changes of expression and function of Cx32, but not claudin-1, without inhibition of cell growth, whereas LY294002 completely inhibited cell growth. These findings indicate that the PI3 kinase pathway rather than the MAP kinase pathway plays an important role for EGF-induced proliferation of rat hepatocytes, and that changes of Cx32 in hepatocytes during the stimulation of DNA synthesis may be in part controlled through MAP kinase. Furthermore, Cx32, but not claudin-1, protein may be a target of activated MAP kinase in hepatocytes.     

Vp130, a chloroviral surface protein that interacts with the host Chlorella cell wall

A protein, Vp130, that interacts with the host cell wall was isolated from Chlorovirus CVK2. From its peptide sequence, the gene for Vp130 was identified on the PBCV-1 genomic sequence as an ORF combining A140R and A145R. In Vp130, the N-terminus was somehow modified and the C-terminus was occupied by 23-26 tandem repeats of a PAPK motif. In the internal region, Vp130 contained seven repeats of 70-73 amino acids, each copy of which was separated by PAPK sequences. This protein was well conserved among NC64A viruses. A recombinant rVp130N protein formed in Escherichia coli was shown not only to bind directly to the host cell wall in vitro but also to specifically bind to the host cells, as demonstrated by fluorescence microscopy. Because externally added rVp130N competed with CVK2 to bind to host cells, Vp130 is most likely to be a host-recognizing protein on the virion.     

XIdax, an inhibitor of the canonical Wnt pathway, is required for anterior neural structure formation in Xenopus.

Wnt signaling pathways are involved during various stages in the development of many species. In Xenopus, the accumulation of beta-catenin on the dorsal side of embryo is required for induction of the organizer, while the head structure formation requires inhibition of Wnt signaling. Here, we report a role for xIdax, a negative regulator of Wnt signaling. XIdax is expressed in neural tissues at the neurula stage, and in the restricted region of the tadpole brain. Ectopic expression of xIdax inhibits the target gene expression, suggesting that xIdax can inhibit canonical Wnt signaling. To examine the function of xIdax, a morpholino oligo for xIdax (xIdaxMO) was designed. An injection into an animal pole cell caused a loss of forebrain. The anterior neural marker expression is decreased in xIdaxMO-injected embryo, suggesting that xIdax is required for anterior neural development. Moreover, a negative regulator that acts downstream of xIdax rescued this defect. We propose that Idax functions are dependent on the canonical Wnt pathway and are crucial for the anterior neural development.     

The critical role of ocular-infiltrating macrophages in the development of choroidal neovascularization

Choroidal neovascularization (CNV) is directly related to visual loss in some eye diseases, such as age-related macular degeneration. Although several human histological studies have suggested the participation of macrophages in CNV formation, the precise mechanisms are still not fully understood. In this study, we elucidated the role of ocular-infiltrating macrophages in experimental CNV using CCR2 knockout (KO) mice, wild-type mice, and C57BL/6 (B6) mice. CCR2 is the receptor of monocyte chemoattractant protein-1, and the number of infiltrating macrophage and the area of CNV were significantly reduced in CCR2 KO mice. Enriched ocular-infiltrating macrophages from B6 mice actually showed angiogenic ability in a dorsal air sac assay. Moreover, their expression of class II, CD40, B7-1 and B7-2 molecules, and the mRNA for potential angiogenic factors, such as vascular endothelial growth factor, basic fibroblast growth factor, and tumor necrosis factor alpha, was also observed. Collectively, we conclude that ocular-infiltrating macrophages play an important role in CNV generation.     

Quantitative analysis for soluble elastin in circulation and cell culture fluids using monoclonal antibody-based sandwich immunoassay

We have newly established 3 distinct murine monoclonal antibodies (MoAbs) against human soluble elastin by using chemically denatured immunogen isolated from human aorta; they are designated as HASG-2, HASG-30, and HASG-61-1. All of these MoAbs were highly reactive with soluble forms of native elastin in normal human serum. HASG-2 and HASG-61-1 MoAbs can recognize soluble bovine elastin as well as human antigen, but HASG-30 cannot. The sandwich enzyme-linked immunosorbent assay (ELISA) for human soluble elastin was developed with HASG-61-1 labeled with peroxidase and HASG-30 immobilized on the microplates. The circulating levels of soluble elastin in human healthy subjects (mean +/- SD; 42.9 +/- 19.9ng/mL; n = 85) could be measured with full accuracy and reproducibility, and gradually increased with aging. The positive correlation between the levels and ages was statistically significant (r = 0.581, p < 0.0001). In addition, we could also determine the concentration of tropoelastin secreted from cultured human dermal fibroblasts accurately by this ELISA. This simple assay can be utilized for the routine clinical laboratory screening of patients with arteriosclerotic vascular diseases or to accurately determine the concentrations of tropoelastin secreted from cultured human cells.     

Sensorless estimation of pressure head and flow of a continuous flow artificial heart based on input power and rotational speed

The present study has proposed a new method for estimating the pressure head (P(t)[mm Hg]) and flow (Q(t)[L/min]) of a centrifugal pump on the basis of voltage (V(t)[V]), current (I(t)[A]), and rotational speed (N(t)[k(rpm)]) of the DC motor for a pump without any additional sensors. In the proposed estimation method, two auto-regressive exogenous (ARX) models are employed. One ARX model has an output, P(t) or Q(t), and three inputs, VI(t) = V(t)I(t) and N(t) and the steady state gain (K) of the system from VI(t) to N(t). It can be assumed that K may include the information on viscosity of blood. The coefficient parameters of this ARX model are identified in an off-line fashion before implantation of the pump. After implantation, P(t) or Q(t) is estimated by the same ARX model with the already identified parameters. The other ARX model is used to identify Kon the basis of VI(t) and N(t) in an on-line fashion every time the viscosity of blood may change. In the experiment, a mock circulatory system consisting of a centrifugal pump and a reservoir with 37% glycerin or water was employed. The root mean square error between measured Q(t) and its estimate obtained from the proposed method was 1.66L/min. On the other hand, a different method based on a single ARX model with inputs of VI(t) and N(t), but without the additional input of K, yielded the corresponding estimation error of 2.22L/min. This means that the proposed method can reduce its estimation error by about 25% in comparison with a method that cannot cope with the change in blood viscosity.     

Marked induction of gelatinases,especially type B,in host fibroblasts by human ovarian cancer cells in athymic mice

Two human ovarian adenocarcinoma cell lines, MCAS-3 and OVISE-3 were found to secrete little of any type of gelatinase in tissue culture. However, when these cell lines were implanted subcutaneously into nude mice the cyst fluids from the resultant tumors contained gelatinase A and/or B. The enzyme activities, especially of gelatinase B, were much higher in the malignant MCAS-3 tumors than in those of the less malignant OVISE-3 tumor cells. To elucidate the origin of gelatinase B in cyst fluids of the MCAS-3 tumors, murine skin fibroblasts (MSF) were isolated from a subcutaneous tumor in a nude mouse and tested for their proteinase secretion in culture. MSF cells, which secreted some gelatinase A and gelatinase B, were induced to secrete high levels of both enzymes, especially gelatinase B, by co-cultivation with MCAS-3 cells. In addition, gelatinase A activity was induced by incubation of MSF cells with the conditioned medium of either MCAS-3 or OVISE-3 cells, whereas gelatinase B was induced only with that of MCAS-3. Although cytokines or growth factors such as IL-1 TGF-1, TNF- or EGF stimulated the secretion of gelatinases A and B from MSF cells, their effects on gelatinase B activity were far less than that of the MCAS-3 conditioned medium. These results indicate that the major part of gelatinase B activity in the cyst fluids of the ovarian tumors is secreted by host interstitial cells stimulated by tumor-derived humoral factors. Similar tumor cell-host cell interactions may be important in the production of various proteinases in other tumor types.     

Chemoprevention of heterocyclic amine-induced mammary carcinogenesis in rats

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is one of the most prevalent carcinogenic heterocyclic amines in the environment, targeting the colon, prostate, pancreas, and mammary gland in rodents. Chemopreventive effects of synthetic and naturally occurring compounds on PhIP-induced rat mammary carcinogenesis were investigated in a series of experiments. In a PhIP feeding model, groups of 20-21 female F344 rats each, were treated with 0.02% PhIP alone or PhIP plus 0.5% 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), 1% green tea catechins, 1% alpha-tocopherol, 0.1% ellagic acid, or 1% chlorophyllin, each in the diet, or 0.1% caffeine in drinking water for 52 weeks. To assess the mechanism of HTHQ and caffeine inhibition of PhIP-induced carcinogenesis, effects of these compound on the in vitro metabolic activation of PhIP were examined in the presence of S9 mix. In the next series of experiments, the PhIP intragastric dose model was applied to allow separate investigation of the effects of chemicals during the initiation and postinitiation periods. In these experiments, female Sprague-Dawley rats were given eight intragastric doses of 100 mg/kg body weight during the first 4-8 weeks for initiation. Either during initiation or after initiation, or only after initiation, animals were treated with either corn or perilla oil at doses of 5 and 20%, conjugated fatty acid derived from safflower oil (CFA-S) or perilla oil (CFA-P) at a dose of 1%, arctiin at doses of 0.02 and 0.2% in the diet, or sodium nitrite (NaNO(2)) at a dose of 0.2% in drinking water. In the PhIP feeding model, administration of PhIP alone for 52 weeks induced adenocarcinomas in 40% of rats, but the incidence was remarkably reduced to 5% by the simultaneous treatment with 0.5% HTHQ, a strong lipophilic phenolic antioxidant, or to 10% by 0.1% caffeine. Administration of 1% chlorophyllin exerted similar, albeit weaker, effects. alpha-Tocopherol at a dose of 0.5% only reduced the multiplicity of carcinomas, and 1% green tea catechins only the mean size of mammary tumors. In a metabolic activation study of PhIP, HTHQ and caffeine clearly inhibited the formation of metabolites. In the PhIP gastric dose model, among the naturally occurring compounds examined, a plant lignan arctiin, perilla oil, which contains a large amount of n-6 alpha-linolenic acid, and CFA-S or CFA-P inhibited mammary tumor development, particularly in the postinitiation period, although a clear dose response was not observed. Treatment with 0.2% NaNO(2) in the initiation period was found to lower the volume of mammary tumors. The present results indicate that a number of compounds may be candidate chemopreventive agents against PhIP-induced mammary carcinogenesis, acting through different mechanisms and depending on the stage of carcinogenesis.     

Alterations of 3-nitrotyrosine concentration in the cerebrospinal fluid during aging and in patients with Alzheimer's disease

To investigate the significance of nitric oxide (NO)-mediated neuron death in aging and Alzheimer's disease (AD), the 3-nitrotyrosine concentration in the cerebrospinal fluid (CSF) was investigated in neurologically normal controls and patients with AD. The 3-nitrotyrosine concentration and the 3-nitrotyrosine/tyrosine ratio significantly increased with advancing age, whereas the tyrosine concentration was unaltered. In patients with AD, the 3-nitrotyrosine concentration and the 3-nitrotyrosine/tyrosine ratio increased significantly (>six-fold) compared with controls of similar age, and increased significantly with decreasing cognitive functions, whereas the tyrosine concentration did not change. These findings suggest that an activation of tyrosine nitration, increase in nitrated tyrosine-containing proteins, and/or its degradation may be involved in brain aging and play an important role in the pathogenesis of AD.     

Bilateral diffuse nephroblastomatosis, pancortical type. A case report with immunohistochemical investigations

A variation of Perlman's syndrome of the pancortical type is reported in a male neonate whose parents were cousins. The patient was the product of a 35-week pregnancy, the Apgar score was 3, and the patient died of respiratory failure one hour and 12 minutes after delivery. Autopsy revealed bilateral diffuse nephroblastomatosis, pancortical type, associated with malformations (usually facial), congenital anomalies of the heart, hepatosplenomegaly, pancreatic islet cell hyperplasia, bilateral cryptorchidism, and hyperflexibility of the left knee joint. Renal immunohistochemical investigations revealed positive bindings with peanut and soybean agglutinins and epithelial membrane antigen along the luminal surface of the epithelium in the moderately differentiated tubules, but not in blastoma or primitive epithelium.