Tyrosinase inhibitory activity of citrus essential oils

Thirteen kinds of citrus essential oils and their volatile flavor constituents were investigated for tyrosinase inhibitory activity. Eureka lemon, Lisbon lemon, Keraji, and Kiyookadaidai significantly inhibited the oxidation of L-dihydroxy phenylalanine (L-DOPA) by mushroom tyrosinase. Citral and myrcene among volatile flavor constituents of citrus essential oils exhibited tyrosinase inhibitory activities with Ki values of 0.318 and 2.38 mM, respectively. The inhibition kinetics analyzed by a Lineweaver-Burk plot indicated that citral is a noncompetitive inhibitor and myrcene is a competitive inhibitor. These results indicated that citral and myrcene are responsible for the tyrosinase inhibitory activity of citrus essential oils.     

Gene expressions of canine angiopoietin-1 and -2 in normal tissues and spontaneous tumours

The angiopoietin (Ang) family of proteins are central to the regulation of angiogenesis. The purposes of this study were to determine cDNA sequences of canine Ang-1 and Ang-2 and investigate their expressions in normal tissues and spontaneous tumours. The cDNA sequences of canine Ang-1 and Ang-2 were 1,494 and 1,488 bp, and the deduced amino acid sequences were 497 and 495 residues, respectively. The cDNA sequences of canine Ang-1 and Ang-2 showed high homology with those of the other mammalian species. Canine Ang-1 and Ang-2 mRNA were detectable in all 22 normal tissues and spontaneous tumours. Higher mRNA expression level of canine Ang-2 was demonstrated in mammary simple carcinomas, haemangiosarcoma and hepatocellular carcinoma in comparison with normal tissues.     

Inhibitory effects of Zingiber officinale Roscoe derived components on aldose reductase activity in vitro and in vivo

Ginger (Zingiber officinale Roscoe) continues to be used as an important cooking spice and herbal medicine around the world. Scientific research has gradually verified the antidiabetic effects of ginger. Especially gingerols, which are the major components of ginger, are known to improve diabetes including the effect of enhancement against insulin-sensitivity. Aldose reductase inhibitors have considerable potential for the treatment of diabetes, without increased risk of hypoglycemia. The assay for aldose reductase inhibitors in ginger led to the isolation of five active compounds including 2-(4-hydroxy-3-methoxyphenyl)ethanol (2) and 2-(4-hydroxy-3-methoxyphenyl)ethanoic acid (3). Compounds 2 and 3 were good inhibitors of recombinant human aldose reductase, with IC50 values of 19.2 +/- 1.9 and 18.5 +/- 1.1 microM, respectively. Furthermore, these compounds significantly suppressed not only sorbitol accumulation in human erythrocytes but also lens galactitol accumulation in 30% of galactose-fed cataract rat model. A structure-activity relationship study revealed that the applicable side alkyl chain length and the presence of a C3 OCH3 group in the aromatic ring are essential features for enzyme recognition and binding. These results suggested that it would contribute to the protection against or improvement of diabetic complications for a dietary supplement of ginger or its extract containing aldose reductase inhibitors.     

Expression of inhibins, activins, insulin-like growth factor-I and steroidogenic enzymes in the equine placenta

In this study, the expression patterns of inhibins, activins, insulin-like growth factor-I (IGF-I) and steroidogenic enzymes in equine placentae recovered during the latter two-thirds of gestation were examined. Concentrations of inhibin A and inhibin pro-alphaC in endometrial and fetal placental tissue homogenates were very low during the period examined, whereas these tissues contained high concentrations of activin A. In both maternal endometrial and fetal placental tissues, activin A levels decreased as pregnancy progressed. Expression of inhibin alpha-subunit was not observed in the placenta using either immunohistochemistry or in situ hybridization. Inhibin/activin betaA-subunit and its mRNA were confined to maternal endometrial glands, whereas immunopositive betaB-subunit was not detected in either endometrial glands or microcotyledons. Cytochrome P450 side chain cleavage enzyme was detected by immunohistochemistry in both endometrial glands and microcotyledons, whereas cytochrome P450 17alpha-hydroxylase/lyase was absent in these tissues. Immunopositive signals for 3beta-hydroxysteroid dehydrogenase and cytochrome P450 aromatase were localized in microcotyledons but not in endometrial glands. Immunohistochemistry revealed that IGF-I was highly expressed in microcotyledons around Day 130, and decreased as pregnancy progressed. Changes in the expression of IGF-I were correlated with the number of PCNA positive cells in the placenta. The present study demonstrated the presence and localized the site of expression of activin, IGF-I and steroidogenic enzymes in equine placental tissues during the latter two-thirds of gestation; the results suggest that activin and IGF-I may be involved in the regulation of placental development.     

Histopathological characteristics of Ito cells and Kupffer cells in the feline liver

The histopathological characteristics of Ito cells and Kupffer cells were investigated in the liver of 21 cats (age range: 6 months -18 years) autopsied in our laboratory during 2003. Immunohistochemical examinations were performed using antibodies against lysozyme, desmin and alpha-smooth muscle actin. No Kupffer cells reacted with the antibody against lysozyme. However, macrophages in the lung and spleen showed a positive reaction with the antibody. This finding suggests a possibility that the amount of lysozyme in the Kupffer cells of feline liver is comparatively small. On the other hand, large vacuole-laden cells were observed in the hepatic perisinusoid of some feline cases, and these cells showed a positive reaction with antibodies against desmin and alpha-smooth muscle actin. These cells could be Ito cells with large lipid vacuoles. This conclusion was supported by electron microscopic observation and oil red O staining. However, no such large vacuole-laden perisinusoidal cells were detected in the liver of young cats less than 2 years old. The present study revealed the histopathological features of Kupffer cells and Ito cells in the feline liver.     

Ex vivo tissue discrimination by visible and near-infrared spectra with chemometrics

The risk of infections from zoonotic pathogens of tissues and/or tissue-derived products has been increasing. One preventive approach in reducing infection risk is tissue decontamination, where selection and screening of highly infectious tissues are strictly followed. Therefore, the development of reliable analytical methods for rapid tissue discrimination is essentially important. In the present study, a procedure has been developed for intact tissue discrimination on the basis of multivariate analysis of visible and near-infrared (Vis-NIR) spectra of certain tissues such as brain, liver, kidney and testis of mice without any pretreatment. Transmittance spectra in the 600- to 1000-nm regions were subjected to a principal component analysis (PCA), and leave-out cross-validation was employed to develop multivariate models for tissue discrimination. The plot of PCA scores against Vis-NIR spectra of brains, kidneys, livers and testes from 11 mice portrayed reliable tissue discrimination. This result suggests that Vis-NIR spectroscopy combined with chemometrics analysis may provide a potentially useful approach for rapid non-destructive discrimination of tissues.     

In vitro and in vivo developmental ability of oocytes derived from porcine primordial follicles xenografted into nude mice

We evaluated the developmental ability of oocytes in porcine primordial follicles xenografted into nude mice. Ovarian tissues from 20-day-old piglets, in which most of the follicles were primordial, were transplanted under the kidney capsules of ovariectomized nude mice. Forty-nine to 89 days after grafting (mean +/- SEM, 66.9 +/- 1.9 days; n = 64), the host mice showed the presence of cornified epithelial cells in their vaginal smears for the first time. The mice were then treated with 4 IU of equine chorionic gonadotropin (eCG) 60 days after first detection of vaginal cornification. Oocytes were collected from the host mice 48 h after treatment with eCG, and then matured. The maturation rates, based on the incidence of first polar body, ranged from 25.1% to 42.5%. They were then fertilized in vitro and cultured in vitro for 6 days, or transferred into estrous-synchronized recipients and recovered after 6 days. On Day 6 of culture, 15.4% of the matured oocytes had cleaved to the 2- to 8-cell stage. However, neither the embryos cultured in vitro nor those transferred and recovered developed to advanced embryonic stages, such as morulae or blastocysts. This result suggests that the developmental ability of xenografted oocytes is insufficient, even after in vitro maturation. Further strategies, such as improvement of hormonal treatment for host mice, are required to enable oocytes in xenografted ovarian tissues to acquire the cytoplasmic maturation necessary for embryonic development.     

Fibrodysplasia ossificans progressiva-like condition in a cat

Fibrodysplasia ossificans progressiva (FOP)-like condition was diagnosed in a Japanese domestic cat with stiffness, marked atrophy of the muscles, and limited mobility of all joints in both the pelvic limbs. Etretinate, a retinoid, was used for medical management; however, no improvement in the clinical signs was observed. Inheritance of the disorder has not yet been demonstrated. Furthermore, the clinical signs and histopathological findings of feline FOP-like condition in the present case differed from those of the previously reported cases.     

Comparison of cell populations derived from canine olfactory bulb and olfactory mucosal cultures

OBJECTIVE: To evaluate the numbers and proportions of olfactory ensheathing cells (OECs) in cell cultures derived from the olfactory bulb (OB) and olfactory mucosa of dogs. ANIMALS: 7 dogs. PROCEDURES: OB tissue and olfactory mucosa from the nasal cavity and frontal sinus were obtained from euthanatized dogs and prepared for cell culture. At 7, 14, and 21 days of culture in vitro, numbers and proportions of OECs, astrocytes, and fibroblasts were determined via immunocytochemistry. Antibody against the low-affinity nerve growth factor receptor p75 was used to identify OECs, antibody against glial fibrillary acidic protein was used to identify astrocytes, and antibody against fibronectin was used to identify fibroblasts. RESULTS: Cultured OECs derived from the olfactory mucosa of the nasal cavity and frontal sinus had similar characteristics. However, whereas OECs in the OB cell cultures constituted approximately 50% of the cells at 7 days and approximately 75% at 21 days the proportion of OECs in cultures derived from both mucosal types was much lower, with approximately 40% OECs at 7 days and approximately 25% at 21 days. Analysis of OEC numbers revealed that these changes were accompanied by corresponding decreases and increases in the population of cells with fibronectin receptors. CONCLUSIONS AND CLINICAL RELEVANCE: Although olfactory mucosal cell cultures yielded a sufficient number of OECs for spinal cord transplantation procedures in dogs, modification of culture conditions would be required to ensure that the derived cell population contained a sufficient proportion of OECs.     

Green-odour compounds have antifungal activity against the rice blast fungus <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis>

Four green-odour compounds—trans-2-hexenal, cis-3-hexenol, n-hexanal, and cis-3-hexenal—were applied (0.85 μg ml⁻¹ as vapour) to rice plants in laboratory conditions to observe their biological activity against the phytopathogenic fungus Maganporthe oryzae, which causes rice blast disease worldwide. Two compounds, trans-2-hexenal and cis-3-hexenal, showed remarkable disease suppression efficacy (99.7% and 100% suppression, respectively), while n-hexanal had moderate (86.5%) and cis-3-hexenol had weak (20.8%) disease-suppressing effects. Pre-application and post-application of trans-2-hexenal or cis-3-hexenal had slight effects on blast incidence, suggesting that these compounds had direct effects to suppress M. oryzae infection. In fact, trans-2-hexenal and cis-3-hexenal exhibited a growth suppression effect on M. oryzae. Interestingly, these two compounds inhibited appressorium formation at lower concentrations than the growth suppression. Studies on the hypersensitive response (HR)-like reaction and plant β-1,3-glucanase activity in rice plant confirmed that induced resistance was not the major factor involved in the disease suppression mechanism. Results of this study conclusively showed that trans-2-hexenal and cis-3-hexenal possess potent inhibitory activities against the growth and the appressorium formation of M. oryzae and could be used as antifungal agents to significantly reduce M. oryzae infections in rice.