Search PubMed⌕ Search

Biomedical subjects

F Furukawa

Publications and source records attributed to F Furukawa.

At least 91 records · Page 5Linked to original sources

[A 13-week subchronic oral toxicity study of chlorophyll in F344 rats].

A 13-week subchronic toxicity study of chlorophyll (containing 40% oil) was performed in both sexes of F344 rats by feeding of CRF-1 powder diet containing 0, 0.18%, 0.55%, 1.66% and 5%, and vehicle (oil) alone. No animals died during the administration period and no changes in body weights and food intakes were found in any dosed groups. Some hematological, serum biochemical and histopathological changes were observed for the 5%-treated group, but these did not suggest obvious toxicity. These findings indicate that the treatment with 1.66% chlorophyll in diet for 13 weeks does not cause any changes in rats and the 5% feeding is not obviously toxic.

Animals↗

Failure of dietary alpha-difluoromethylornithine to inhibit gastric carcinogenesis in rats after 8 weeks of treatment with N-methyl-N'-nitro-N-nitrosoguanidine and sodium chloride.

The modifying effects of alpha-difluoromethylomithine (DFMO) on glandular stomach carcinogenesis after initiation with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and sodium chloride were investigated in male outbred Wistar rats. Animals were simultaneously given MNNG solution (100 ppm) as their drinking water and diet supplemented with 10% sodium chloride for 8 weeks, and administered DFMO (dietary levels of 2000 ppm or 500 ppm) and tap water for the following 70 weeks. The DFMO treatment did not show any tendency to inhibit the development of gastric adenocarcinomas. The incidences and multiplicities of atypical hyperplasias in the glandular stomachs were also comparable in all groups of rats given MNNG/sodium chloride. Neither gastric carcinomas nor atypical hyperplasias were observed without the carcinogen treatment. Thus, DFMO did not exert any inhibitory effects when given during the post-initiation phase of two-stage glandular stomach carcinogenesis in rats initiated with MNNG and sodium chloride for 8 weeks.

Adenocarcinoma↗

Human squamous-cell-carcinoma cell line (DJM-1) cells synthesize P-cadherin molecules via an elevation of extracellular calcium: calcium regulates P-cadherin-gene expression at the translational level via protein tyrosine phosphorylation.

Spatially-regulated P-cadherin expression is crucial for maintaining the normal epidermal architecture. P-cadherin expression in cutaneous squamous-cell carcinomas (SCC) is altered, and may participate in tumor progression. We therefore investigated how P-cadherin expression was regulated in a cultured cutaneous SCC cell line (DJM-1). At low calcium concentration (0.05 mM), DJM-1 cells expressed P-cadherin weakly in the cytoplasm. At a higher calcium concentration, P-cadherin was promptly translocated to the cell surface within 30 min, gradually increased on the cell surface for up to 48 hr, and was continuously expressed for at least 7 days. During this time course, the total amount of P-cadherin protein had increased, whereas the steady-state mRNA levels for P-cadherin had not changed. The inhibition of protein synthesis by cycloheximide, but not the inhibition of gene transcription by actinomycin-D, completely suppressed the expression of P-cadherin. The effect of calcium was inhibited by tyrphostins but not by H-7, cholera toxin, or dibutylic cyclic AMP. Increments in the extracellular calcium concentration did not mobilize the intracellular calcium pool, and were accompanied by the tyrosine phosphorylation of a 62-kDa protein. In addition, DJM-1 cells expressed mRNA for a calcium-sensing receptor originally demonstrated in the parathyroid gland. The results suggest an unique mechanism for regulating P-cadherin gene expression in DJM-1 cells by extracellular calcium, which stimulates the de novo synthesis of P-cadherin at the translational level through protein tyrosine phosphorylation.

Base Sequence↗

Comparative study on organ-specificity of tumorigenicity, mutagenicity and cell proliferative activity induced by dimethylnitrosamine in Big Blue mice.

Recently, we have shown that dimethylnitrosamine (DMN) treatments increase lacI mutant frequency in the liver, kidney and lung but not in other organs, and also enhance cell proliferation only in the bronchial epithelia. In the present study, organ specificity of tumorigenicity induced by DMN was compared to those of lacI mutation and cell proliferation in Big Blue mice. Male 8-week-old Big Blue mice were treated with daily i.p. injections of 1 or 10 mg/kg DMN for 5 days, or a single i.p. injection of 5 or 10 mg/kg DMN. Except for the 10 mg/kg x 5 DMN group, all animals survived until 78 weeks after the first treatment of DMN. In the present study, the induction of cell proliferation in the bronchial epithelia was confirmed in a dose-dependent manner. At the termination of 78 weeks, it was histopathologically shown that the DMN-treated mice developed liver cell tumor in three out of seven (43%) of the 5 mg/kg group, renal tubule dysplasia in three out of seven (43%) of the 1 mg/kg x 5 group, and duodenal adenocarcinoma in one of seven (14%) of the 1 mg/kg x 5 group, although no neoplastic or preneoplastic lesions were found in the control mice. Because non-transgenic C57BL/6 mice are resistant to developing spontaneous liver cell and duodenal tumors, it was speculated that even these low doses of DMN could be sufficient to initiate target cells. Our results thus suggest that organ specificity of tumorigenicity by DMN is in favorable agreement with that of lacI mutation but not with possibly temporal cell proliferation induced by DMN.

Animals↗

Roles of E- and P-cadherin in the human skin.

The Ca(2+)-dependent cell-cell adhesion molecules, termed cadherins, are subdivided into several subclasses. E (epithelial)- and P (placental)-cadherins are involved in the selective adhesion of epidermal cells. E-cadherin is expressed on the cell surfaces of all epidermal layers and P-cadherin is expressed only on the surfaces of basal cells. Ultrastructural studies have shown that E-cadherin is distributed on the plasma membranes of keratinocytes with a condensation in the intercellular space of the desmosomes. During human skin development P-cadherin expression is spatiotemporally controlled and closely related to the segregation of basal layers as well as to the arrangement of epidermal cells into eccrine ducts. In human skin diseases E-cadherin expression is markedly reduced on the acantholytic cells of tissues in pemphigus and Darier's disease. Cell adhesion molecules are now considered to play a significant role in the cellular connections of cancer and metastatic cells. Reduced expression of E-cadherin on invasive neoplastic cells has been demonstrated for cancers of the stomach, liver, breast, and several other organs. This reduced or unstable expression of E- and P-cadherin is observed in squamous cell carcinoma, malignant melanoma, and Paget's disease, but cadherin expression is conserved in basal cell carcinoma. Keratinocytes cultured in high calcium produce much more intense immunofluorescence of intercellular E- and P-cadherin than those cells grown in low calcium. E-cadherins on the plasma membrane of the keratinocytes are shifted to desmosomes under physiological conditions, and therein may express an adhesion function in association with other desmosomal cadherins. Soluble E-cadherins in sera are elevated in various skin diseases including bullous pemphigoid, pemphigus vulgaris, and psoriasis, but not in patients with burns. Markedly high levels in soluble E-cadherin are demonstrated in patients with metastatic cancers.

Cadherins↗

Spontaneous hair follicle cycling may influence the development of murine contact photosensitivity by modulating keratinocyte cytokine production.

The development of murine contact hypersensitivity is influenced by hair follicle cycling. Here, we have examined hair cycle-associated fluctuations of murine contact photosensitivity (CPS) to tetrachlorosalicylanilide (TCSA) and its immunologic mechanism(s). When the CPS outcome was monitored in correlation with their spontaneous, synchronized hair cycling, mice aged 8 and 14 weeks, with most of their hair follicles in telogen, exhibited strong CPS responses, whereas 4-, 11-, and 16-week-old mice with a predominance of anagen follicles in a large area of their integument exhibited lower responses. This suggests that the development of CPS is inhibited in mice with anagen hair follicles. Antigen-specific, T-cell receptor V beta 7+ suppressor T cells, which are recognized to down-regulate the CPS response to TCSA, were not generated in sensitized anagen mice. Culture supernatants of epidermal cells derived from mice with anagen hair follicles contained factor(s) that suppress in vivo the development of CPS. It was found that levels of mRNA for tumor necrosis factor alpha (TNF alpha) were markedly decreased in epidermal cells from early anagen to telogen mice, whereas message for IL-1 receptor antagonist (IL-1ra) was transcribed increasingly during this hair cycling. These findings suggest that altered keratinocyte production of these cytokines is involved in mediating the anagen-associated depression of CPS.

Age Factors↗

Enhancing effects of captafol on the development of GST-P-positive liver cell foci in a medium-term bioassay, and protection by L-cysteine of the enhancement in rats.

The modifying effects of captafol and protective effects of L-cysteine on the development of glutathione S-transferase placental form-positive (GST-P +) foci of the liver and expression of proliferating cell nuclear antigen (PCNA) in the kidney were investigated in a medium-term bioassay using D-galactosamine (DGA) in rats. Male 6-week-old F344 rats were initially given a single i.p. injection (200 mg/kg) of diethylnitrosamine (DEN) and after 2 weeks on basal diet, received two i.p. injections of DGA (300 mg/kg) at the ends of weeks 2 and 5, and were fed a diet supplemented with test chemicals for weeks 3-8. Animals in group 1 were given 1500 ppm captafol in the diet, while group 2 received 1500 ppm captafol in diet as well as 1500 ppm L-cysteine in drinking water, animals in control group being given basal diet alone. Positive results regarding increased numbers and areas of GST-P + liver cell foci were obtained in rats treated with captafol alone. On the other hand, significant reduction by L-cysteine in the areas of GST-P + liver cell foci initiated by DEN and promoted by captafol was observed. In addition, the PCNA-labelling indices of renal tubule cells were elevated in rats treated with captafol alone and significantly reduced in rats treated simultaneously with L-cysteine. The protocol used in the present study therefore allowed the in vivo determination of promoting effects of captafol and inhibitory influence of L-cysteine by analyzing GST-P + foci in the livers as marker lesions, within a relatively short period of 8 weeks. Thus, this bioassay protocol could have applicability as a new in vivo assay system for the screening of hepatic carcinogenic or anti-carcinogenic agents.

Animals↗

T-cell proliferation to superantigen-releasing Staphylococcus aureus by MHC class II-bearing keratinocytes under protection from bacterial cytolysin.

Skin colonization with Staphylococcus aureus may exacerbate skin disorders by activation of lesional T cells with release of superantigens. Although T cells are effectively stimulated by staphylococcal superantigens in the presence of epidermal accessory cells, it remains to be elucidated whether in vivo cutaneous colonization with S. aureus can activate T cells. We examined how T cells are stimulated in the presence of keratinocytes by mitomycin C (MMC)-treated S. aureus that are unable to propagate but retain their ability to produce superantigens. Peripheral blood mononuclear cells (PBMCs) proliferated well in response to MMC-treated superantigen-producing S. aureus and bacterial supernatants. When purified T cells were cultured with MMC-treated S. aureus or supernatant in the presence of interferon-gamma-pre-treated keratinocytes, the supernatant, but not MMC-treated S. aureus, stimulated T cells. MMC-treated S. aureus had a cytotoxic effect on keratinocytes. Furthermore, keratinocytes were highly susceptible to alpha-toxin compared with monocytes and B cells functioning as accessory cells in PBMCs. This suggests that a lack of response of T cells to S. aureus plus keratinocytes is due to damage of superantigen-presenting function of keratinocytes by cytolysin. The activity of alpha-toxin was much less stable than that of superantigen during incubation. Given that S. aureus-colonized skin provides circumstances in which viable keratinocytes are exposed to superantigens but not to active cytolysin(s), skin-infiltrating T cells may be effectively stimulated by S. aureus.

Adult↗

Altered permeability and disordered cutaneous immunoregulatory function in mice with acute barrier disruption.

In vivo and in vitro T-cell-activating ability of murine epidermal cells (EC) was investigated in acutely barrier-disrupted skin by extraction of epidermal lipids with acetone or removal of corneocytes by tape stripping. Contact sensitivity (CS) to 2,4-dinitrofluorobenzene (DNFB) and picryl chloride (PCl) and contact photosensitivity (CPS) to tetrachlorosalicylanilide (TCSA) were significantly augmented when challenged or sensitized at sites treated with acetone 24 h before, compared with the intact skin. CS to DNFB was also enhanced by tape stripping, but not by water rubbing, suggesting that physical stress or a toxic effect of acetone was not responsible for the augmentation. Semi-quantification of TCSA-EC photoadducts showed markedly increased permeability of hapten in the epidermis 24 h after acetone treatment. Bioactive IL-1alpha was more pronounced in barrier-disrupted than in intact skin. Lymph node T cells from PCl-sensitized mice proliferated significantly more in a hapten-specific and co-stimulatory molecule-dependent manner in response to trinitrophenylated (TNP) EC from acetone-treated skin than to those from untreated skin. Immunofluorescence staining of epidermal sheets and flow cytometric analysis of dispersed EC showed that subpopulations of Langerhans cells (LC) in acetone-rubbed or tape-stripped skin expressed major histocompatibility complex class II CD54 and CD86 molecules at levels higher than the rest of LC and LC from water-treated or untreated epidermis. Therefore, not only increased permeability of hapten through the epidermis but also altered immune functions of EC potentiate T-cell activation in acute barrier disruption. Such augmentation of immune reactivity may be critical to elimination of environmental noxious agents that penetrate easily into the barrier-disrupted epidermis.

Acetone↗

Evaluation of soluble cell adhesion molecules in atopic dermatitis.

Recent studies have indicated the importance of cell adhesion molecules (CAMs) between the vascular endothelium and activated leukocytes in various inflammatory skin diseases. Soluble forms of CAMs (sCAMs) have also been detected in sera from such diseases. In order to elucidate the role of the soluble forms in skin inflammation, we determined the serum levels of E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) in patients with atopic dermatitis (AD). Using an enzyme-linked immunosorbent assay, we quantified sCAMs levels in 21 patients with atopic dermatitis and in 16 healthy controls. In severe AD patients, levels of these three types of sCAMs were markedly elevated. sE-selectin was significantly elevated in severe AD over the levels in mild AD. A positive correlation with individual clinical activity was found for changes in the sE-selectin and sVCAM-1 levels. sE-selectin levels were correlated with the serum IgE levels and the number of eosinophils. The sVCAM-1 level was also significantly correlated with the number of monocytes. Among these three molecules, sE-selectin appeared to be the most sensitive clinical parameter in monitoring the clinical course of AD patients.

Adolescent↗

Mechanistic insights into chemopreventive effects of phenethyl isothiocyanate in N-nitrosobis(2-oxopropyl)amine-treated hamsters.

The influence of phenethyl isothiocyanate (PEITC) on cell kinetics in the target organs of N-nitrosobis(2-oxopropyl)amine (BOP) tumorigenicity and on xenobiotic-metabolizing enzymes was investigated in hamsters. Female 5-week-old Syrian hamsters were given a single s.c. dose of 0, 20 or 50 mg/kg of BOP 2 h after receiving PEITC by gavage at a dose of 0, 100 or 250 mumol/animal (0, 16.3 or 40.8 mg/animal). Six and 22 h after the BOP administration, hamsters were killed and tissues were sampled. Proliferating cell nuclear antigen immunohistochemistry demonstrated significant reduction (P < 0.05-0.001) by PEITC of the labeling indices in the pancreatic acini and ducts, bronchioles, and renal tubules of the BOP-treated animals in a dose-dependent manner. In the lungs, the PEITC pretreatment significantly (P < 0.001) reduced the O6-methyldeoxyguanosine levels as compared to the BOP-alone value. Immunoblot analysis of liver cytochrome P450 isoenzymes showed CYP 2B1 to be mainly involved in the metabolic activation of BOP. PEITC significantly (P < 0.05) inhibited the induction of several isoenzymes, including CYP 2B1, while lowering the hepatic glutathione S-transferase activity as well as glutathione levels, regardless of BOP administration. Our results thus suggest that PEITC exerts its chemopreventive activity against BOP initiation of carcinogenesis in hamsters by decreasing cell turnover and DNA methylation in the target organs, and by influencing hepatic xenobiotic-metabolizing phase I enzymes, although the relationship, if any, of the latter with the former events remains to be investigated.

Animals↗

Animal models of cutaneous lupus erythematosus and lupus erythematosus photosensitivity.

Over the past decade, the most exciting and important finding in SLE-prone mice is the discovery of Fas/Fas ligand systems in the pathogenesis of autoimmune phenomena. A human model for murine lpr/gld disease has also been reported recently. Furthermore, as shown in Table 2, studies on Ig variable region genes, TCR genes and MHC class II genes have given us much information concerning human and murine SLE. With respect to cytokines, IL-2 deficiency and the key role of IL-6 have been found in SLE-prone mouse strains, and Th2 cytokine production has been demonstrated to play a more pathogenic role than Th1 cytokine production in human and murine SLE except for MRL/pr mice. TGF is also very intriguing because TGF-beta knockout mice show SLE-like autoantibodies and Sjögren syndrome-like lymphoproliferation. Apart from these basic scientific investigations, there are also many promising and practical therapeutic approaches. In particular, treatments with anti-CD4 antibody and murine CTLA4Ig which bound B7 and blocked binding of CD28 to B7 are outstanding. However, it remains obscure whether such new approaches are effective for the skin lesions of SLE-prone mice, although some immunosuppressive agents such as FK506, cyclosporin and Chinese herbal medicines have been evaluated to determine their selective effects on the skin lesions of MRL/lpr mice. Needless to say, mouse models are not identical, but similar, to human diseases. However, they are important in the search for the underlying pathogenesis of autoimmune diseases on the basis of careful evaluation of the similarities and differences between human diseases and these models. If such studies are steadily performed, then inbred or experimental models will become more promising tools for the investigation of cutaneous lupus erythematosus.

Animals↗

Subacute and chronic prurigo effectively treated with recombination interferon-gamma: implications for participation of Th2 cells in the pathogenesis of prurigo.

Subacute and chronic prurigo is notoriously resistant to usual therapies. Four of five patients with a subacute or chronic form of prurigo responded well to daily intravenous injections of recombinant interferon-gamma (rIFN-gamma) (0.25-2 x 10(6) Japan Reference Unit (JRU; 1 JRU roughly corresponds to 4 NIH units) daily, for 10-14 days). In one patient examined, the dermal portion of lesional skin before the treatment contained considerable amounts of mRNA for interleukin (IL)-4, IL-5, and IL-10, indicative of infiltration of Th2 cells. Furthermore, the administration of rIFN-gamma selectively down-regulated mRNA for Th2 cytokines, IL-4 and IL-10 in peripheral blood mononuclear cells. These findings suggest that Th2 cells play a pathogenic role in these types of prurigo and that rIFN-gamma exerts its efficacy by inhibiting Th2 cells. Our pilot study suggests that the systemic administration of rIFN-gamma is a therapeutic alternative for the treatment of recalcitrant prurigo.

Adult↗

Thrombin and trypsin induce granulocyte-macrophage colony-stimulating factor and interleukin-6 gene expression in cultured normal human keratinocytes.

We studied the effects of serine proteases on cytokine gene expression by cultured normal human keratinocytes. In resting keratinocytes, steady-state mRNA levels for interleukins IL-1 alpha, IL-1 beta, IL-7, and IL-8, transforming growth factors alpha and beta, and tumor necrosis alpha were sufficient to be detected by our reverse transcriptase-polymerase clozin reaction method. Incubation of keratinocytes with 25 nM trypsin or 1 unit/ml thrombin for 24 hr selectively upregulated mRNA levels for granulocyte-macrophage colony-stimulating factor (GM-CSF) and Il-6 to detectable levels. Keratinocytes secreted GM-CSF and IL-6 protein in response to these proteases. Monensin did not inhibit the gene expression for the cytokines, thereby excluding the possibility of intervention by secreted molecules. Aprotinin and argatroban inhibited the effects of the proteases. SFLLRN and SLIGRL, tethered ligand receptor peptides for thrombin receptor and for proteinase-activated receptor 2 (PAR-2), respectively, duplicated the effects of the proteases on keratinocytes, which expressed mRNA for both receptors. Trypsin increased tyrosine phosphorylated proteins and intracellular free calcium concentrations. Tyrphostin, pertussis toxin, or H-7 suppressed trypsin- and thrombin-induced GM-CSF gene expression. Our results demonstrate that the serine proteases activate thrombin receptors and PAR-2 on keratinocytes, triggering intracellular signaling and then inducing the synthesis of GM-CSF. We speculate that serine proteases modulate the course of physiological and pathological processes in the skin by stimulating keratinocytes to produce the cytokines.

Aprotinin↗

Wells' syndrome: a pathogenic role for circulating CD4+CD7- T cells expressing interleukin-5 mRNA.

Wells' syndrome, or eosinophilic cellulitis, is a rare dermatosis characterized histologically by a dermal infiltrate of eosinophils, lymphocytes and histiocytes between collagen bundles and amorphous or granular eosinophilic deposits on collagen, constituting flame figures. We report a 54-year-old woman with eosinophilic cellulitis whose peripheral blood showed a marked eosinophilia and a high proportion of CD4+CD7- cells before treatment. Reverse transcriptase-polymerase chain reaction revealed that CD4+CD7- cells, but neither CD4+CD7+ nor CD4-CD8+ cells, in the circulating mononuclear cells expressed mRNA for interleukin (IL)-5, the major cytokine involved in eosinophilia. The proportion of CD4+CD7- cells decreased, and expression of mRNA for IL-5 disappeared in the peripheral blood, when the disease was treated by the administration of intravenous recombinant interferon-gamma. These findings suggest that circulating CD4+CD7- T cells play a pivotal role in the pathogenesis of eosinophilic cellulitis by producing IL-5.

Antigens, CD7↗

[Effects of 16-week dietary administration of 2-amino-3,8-dimethylimidazo[4, 5-f]quinoxaline in rats].

2-Amino-3,8-dimethylimidazo[4, 5-f]quinoxaline (MeIQx), a heterocyclic amine found in cooked meats, is carcinogenic in mice and rats at high doses. In order to examine the toxicity including preneoplastic changes at the lower doses, a total of 170 male Fischer 344 rats were administered MeIQx for 16 weeks at a dose of 100, 10, 1, 0.1, 0.01, 0.001 ppm or 0 ppm in the diet. The numbers of GST-P positive foci and BrdU-labeling indices in the liver were significantly increased by the dietary administration of 10 ppm and 1 ppm or more of MeIQx respectively, when compared with the basal diet-fed control rats. Aberrant cry p tfoci (ACF) were also significantly increased in the 100 ppm MeIQx group as compared to the control value. No histopathological changes indicating obvious toxicity of MeIQx were observed in the major organs other than the liver and large intestine. In conclusion, our results clearly indicate that MeIQx selectively targets the liver and large intestine of rats as organs for the toxicity, but dose not affect the other major organs at low doses.

Animals↗

Reappraisal of eight representative carcinogenic and non-carcinogenic compounds in a new medium-term rat liver bioassay using D-galactosamine.

The carcinogenic potential of eight different compounds was assayed in a new medium-term carcinogenicity bioassay using D-galactosamine (DGA) as a non-surgical method to induce regeneration in place of partial hepatectomy (PH). Male rats were initially given a single i.p. injection (200 mg/kg) of diethylnitrosamine (DEN) and after 2 weeks on basal diet, received two i.p. injections of DGA (300 mg/kg) at the end of weeks 2 and 5. They were treated with one of the test compounds aflatoxin B1, benzo[a]pyrene, diethylstilbestrol, urethane, sodium saccharin, bucetin, D-mannitol and sodium chloride in the diet or basal diet alone for weeks 3-8. Carcinogenic potential was assessed by comparing the numbers and areas per cm2 of glutathione S-transferase placental form-positive (GST-P+) foci in the livers of treated animals with those of the control animals given DEN/DGA alone. Positive estimations of carcinogenicity were obtained for the hepatocarcinogens aflatoxin B1, diethylstilbestrol or urethane, and for the non-liver carcinogen benzo[a]pyrene. Negative values were shown in rats treated with the non-carcinogens, D-mannitol and sodium chloride. The two other non-liver carcinogens sodium saccharin and bucetin, also did not exert positive effects in the system. The present data are consistent with findings in previous medium-term bioassays using PH. Our results thus confirm that the present bioassay protocol with repeated administration of DGA instead of PH may offer a new and sensitive non-invasive method to screen large numbers of environmental carcinogens.

Animals↗