Two-week, but not 1-week, hypoxic exposure enhances nitric oxide-mediated basal tone regulation in rat resistance pulmonary arteries

We measured internal diameter (ID) changes in resistance and conduit pulmonary arteries of 1- and 2-week hypoxic rats and normoxic control rats in response to nitric oxide synthase (NOS) inhibitors in vivo. At 2 weeks of hypoxic exposure, the ID reduction as a result of NOS inhibition was enhanced within the resistance arteries, but not at 1 week of hypoxia.     

Gain-of-function polymorphism in mouse and human Ltk: implications for the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus (SLE), a complex multigenic disease, is a typical antibody-mediated autoimmune disease characterized by production of autoantibodies against a variety of autoantigens and immune complex-type tissue inflammation, most prominently in the kidney. Evidence suggests that genetic factors predisposing to aberrant proliferation/maturation of self-reactive B cells initiate and propagate the disease. In SLE-prone New Zealand Black (NZB) mice and their F1 cross with New Zealand White (NZW) mice, B cell abnormalities can be ascribed mainly to self-reactive CD5+ B1 cells. Our genome-wide scans to search for susceptibility genes for aberrant activation of B1 cells in these mice showed evidence that the gene, Ltk, encoding leukocyte tyrosine kinase (LTK), is a possible candidate. LTK is a receptor-type protein tyrosine kinase, belonging to the insulin receptor superfamily, and is mainly expressed in B lymphocyte precursors and neuronal tissues. Sequence and functional analyses of the gene revealed that NZB has a gain-of-function polymorphism in the LTK kinase domain near YXXM, a binding motif of the p85 subunit of phosphatidylinositol 3-kinase (PI3K). SLE patients also had this type of Ltk polymorphism with a significantly higher frequency compared with the healthy controls. Our findings suggest that these polymorphic LTKs cause up-regulation of the PI3K pathway and possibly form one genetic component of susceptibility to abnormal proliferation of self-reactive B cells in SLE.     

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.     

Functional CD4+T cell subsets defined by expression of CD45RC and NTA260 antigens and age-associated polarization in murine lupus

Using two mAb, one specific to the alternative exon 6-dependentepitope of CD45 molecules(JH6.2) and one a natural thymocytotoxicautoantibody (NTA) with an unknown reactive epitope (NTA260),we subdivided splenic CD4⁺ T cells from 2-month-old BALB/c miceinto five phenotypically distinct subsets. CD45RC⁺NTA260^–(SI) cells were phenotypically analogous to CD4⁺ T cells predominatingin newborn mice and produced a significant amount of IL-2, butnot so IL-4, IL-10 or IFN- when stimulated with immobilizedanti-CD3 mAb in vitro. They appeared to consist mainly of naiveT_hP cells. The CD45RC⁺;NTA260⁺ (S II) subset also produced IL-2,but not other cytokines; however, the IL-2 levels produced weremuch higher than seen with the S I subset, thereby suggestingthe predominance of further maturated T_hP cells. The D45RC^–NTA260⁺(S III) subset mainly produced IL-4, IL-10, IFN- and less IL-2,and contained memory cells that helped the secondary antibodyresponse to a recall antigen, and hence contained T_h2 and probablya mixture of T_h0 and T_h1 cells. The CD45RC^–NTA260^–(S IV) subset was a poor responder to the immobilized anti-CD3mAb. The CD45RC^brightNTA260^dull(S V) subset consisted of a smallnumber of cells that were phenotypically analogous to activatedCD4⁺ T cells. While an age-associated decrease in the proportionof S I and less markedly in S II and in turn increase in S IIIsubsets of CD4⁺ T cells occurred in normal BALB/c mice, autoimmunedisease-prone (NZBxNZW)F₁ mice showed a marked age-associateddecrease in the proportion of not only S I, II but also IIIsubsets. As aged (NZBxNZW)F₁ mice carry CD4⁺ T helper cellsfor IgG anti-DNA antibody production, such age-associated polarizationto the S IV subset appears to be critical in the pathogeneslsof autoimmune disease in these mice.     

Modifying effects of 1'-acetoxychavicol acetate (ACA) and the novel synthetic retinoids Re-80, Am-580 and Am-55P in a two-stage carcinogenesis model in female rats

Effects of dietary administration of 1'-acetoxychavicol acetate (ACA) and the novel synthetic retinoids 4-[1-hydroxy-3-oxo-3-(5,6,7,8-tetrahydro-3-hydroxy-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl]benzoic acid (Re-80); 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carboxamido]benzoic acid (Am-580); and 6-[(3,5-di-tert-butylphenyl) carbamoyl]nicotinic acid (Am-55P) were examined using a two-stage rat carcinogenesis model. A total of 190 female SD rats was treated sequentially with 1,2-dimethylhydrazine (DMH, s.c.); 7,12-dimethylbenz(a)anthracene (DMBA, i.g.); and 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN, in the drinking water) during the first three weeks (DDD-initiation), and an additional 60 rats received the vehicle alone (non-initiation). One week after the completion of the initiation period, they were divided into nine groups and administrated Re-80 (at dose levels of 1.0 or 0.4 ppm), Am-580 (20 or 4 ppm), Am-55P (20 ppm), ACA (100 ppm), all-trans-retinoic acid (10 or 2 ppm) or no supplement in the diet for 33 weeks, until survivors were euthanatized at week 37 weeks. After DDD-initiation, all-trans-retinoic acid at the high dose delayed the development of mammary tumors. The multiplicity of colon tumors in the group fed Am-55P and the incidences of nephroblastomas with ACA or Am-580 were decreased as compared with the control values, but the other chemicals had no modifying effects on tumor development in any organs. Thus, among ACA and the novel synthetic retinoids tested, only Am-55P showed a weak inhibitory effect on a neoplasm of general interest under the present experimental conditions.     

Determination of substituent distribution in cellulose ethers by means of a 13C NMR study on their acetylated derivatives, 4. O-methyl-O-hydroxyalkylcelluloses

A structural study on O-methyl-O-hydroxypropylcellulose (MHPC) and on O-methyl-O-hydroxyethylcellulose (MHEC) was performed by means of a ¹³C NMR analysis after acetylation of the unsubstituted hydroxyl groups at the anhydroglucose ring and those at the end of the substituents. The carbonyl signal of the acetyl group in acetylated MHPC and MHPC samples was found to be resolved into four peaks according to the location of the acetyl function either at the 2-, 3- and 6-position of an anhydroglucose unit or at the end of an oligo(oxyalkylene) substituent, allowing to determine the distribution of methyl and oligo(oxyalkylene) substituent groups. The methyl signal of the methoxy group in MHPC was also found to be sensitive to its position either at the anhydroglucose unit or at the end of the oligo(oxypropylene) substituent.     

Cytopathic astrovirus isolated from porcine acute gastroenteritis in an established cell line derived from porcine embryonic kidney.

A cytopathic astrovirus was isolated from pigs with acute diarrhea in an established cell line that was derived from porcine embryonic kidneys with the aid of trypsin. The virus showed a distinct cytopathic effect characterized by an enlargement of cells and the appearance of fine granules in the cytoplasm. Porcine astrovirus was shown to have an RNA genome, as determined by the effect of 5-iodo-2'-deoxyuridine on its replication, and five polypeptides with molecular masses of 13,000, 30,000, 31,000, 36,000, and 39,000 daltons; and it was shown to be stable to lipid solvents and heating at 50 degrees C for 30 min but somewhat labile to acid (pH 3.0). The buoyant density of the isolate determined in CsCl was 1.35 g/ml. Seroconversion to the virus was evident in the paired serum specimens obtained from pigs with diarrhea that were housed at the farm where the disease occurred. The neutralization test on serum specimens collected randomly from 128 adult pigs of eight herds revealed that 50 of the serum specimens were positive for antibody to porcine astrovirus, although there was considerable variation in the prevalence among herds, ranging from 0 to 83%. Hysterectomy-produced, colostrum-deprived, 4-day-old pigs developed mild diarrhea after oral exposure to porcine astrovirus propagated in the cell culture; and the virus was isolated again from diarrheal stool specimens.     

Characterization of spontaneous dermatitis in beige rats with IgE hyperproduction

BACKGROUND: Atopic dermatitis (AD) is a common skin disease characterized by chronic recurrent eczematous lesions, but its exact etiology and mechanism are unclear. We found that beige rats (DAbg/bg), a mutant model of Chediak-Higashi syndrome, develop skin lesions characterized by pruritus, excoriation, erosion and alopecia. We describe the beige rat and examine its possible usefulness as an AD model. METHODS: Beige rats of 4, 8, 13, 16, 26 and 52 weeks were used. Histological analysis of the skin was performed. Plasma IgE and cytokines were measured. Th1 and Th2 cytokines and RANTES mRNA expression of skin and lymph nodes were evaluated. Passive cutaneous anaphylaxis (PCA) reactions were examined, and maximization tests were conducted. RESULTS: Skin lesions begin to develop with increases in serum IgE levels and the expression of IL-4 mRNA in the lymph node and skin. Histologically, skin lesions are characterized by acanthosis, ulceration and inflammatory cell infiltration in the dermis. Inflammatory cells consist of CD3+, CD4+, ED1+, ED2+ and I-A+ mononuclear cells, eosinophils, degranulated mast cells and neutrophils accompanying interleukin (IL)-4, interferon (IFN)-gamma and RANTES mRNA expressions of the skin. Inflammatory cells are reduced during chronification with decreased expressions of IL-4, IFN-gamma and RANTES mRNA. In addition, the rats show a high sensitivity to PCA reactions and maximization tests. CONCLUSIONS: Our results show that some of the skin lesions of beige rats are morphologically similar to human AD, being characterized by inflammatory cell composition in the acute phase, and increased IgE and RANTES levels. However, the inflammatory process and cytokine expression pattern are different from those in human AD.     

Lack of synergism among DMAB, BOP, and MNU in induction of carcinomas of the rat ventral prostate.

The present experiment was undertaken to investigate possible synergism in induction of rat prostate tumor. F344 rats were repeatedly administered the prostate carcinogens 3,2'-dimethyl-4-aminobiphenyl (DMAB),N-nitrosobis(2-oxopropyl)amine(BOP), and N-methylnitrosourea (MNU) sequentially or together at times of hormonal castration induced regenerative cell proliferation of prostate epithelial cells. Group 1 animals received two 100 mg/kg doses of DMAB, two 20 mg/kg applications of BOP, and two times 15 mg/kg of MNU. Groups 2, 3, and 4, respectively, received each of the carcinogen treatment alone. Group 5 was given 6 applications of all three in combination, each at one-third the dose administered to the other groups. The results showed a clear synergism in enhanced tumor development in the colon but not in the prostate, in which the incidence of lesions induced by the three carcinogens was similar to that with DMAB alone.