An intratracheal instillation bioassay system for detection of lung toxicity due to fine particles in f344 rats

It is an urgent priority to establish in vivo bioassays for detection of hazards related to fine particles, which can be inhaled into deep lung tissue by humans. In order to establish an appropriate bioassay for detection of lung damage after particle inhalation, several experiments were performed in rats using quartz as a typical lung toxic particle. The results of pilot experiments suggest that Days 1 and 28 after intratracheal instillation of 2 mg of fine test particles in vehicle are most appropriate for detection of acute and subacute inflammatory changes, respectively. Furthermore, the BrdU incorporation on Day 1 and the iNOS level on Day 28 proved to be suitable end-point markers for this purpose. An examination of the toxicity of a series of particles was performed with the developed bioassay. Although some materials, including nanoparticles, demonstrated toxicity that was too strong for sensitive assessment, a ranking order could be clarified. The bioassay thus appears suitable for rapid hazard identification with a possible ranking of the toxicity of various particles at single concentrations.     

Ethanol Does Not Promote MeIQx-initiated Rat Colon Carcinogenesis Based on Evidence from Analysis of a Colon Cancer Surrogate Marker

Epidemiological studies suggest that alcohol consumption increases the risk of developing colorectal cancer. However, the data are confounded by numerous cosegregating variables. To cast further light on the relationships between alcohol intake and colon cancer development, 21-day-old male F344/DuCrj rats were fed 200 ppm 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) in their diet for 8 weeks and doses of 0, 0.1, 0.3, 1, 3, 10 and 20% of ethanol in their drinking water ad libitum for 16 weeks thereafter. The rats were sacrificed after 24 weeks of experiment, and aberrant crypt foci (ACF), surrogate lesions for colon cancer, were examined under a light microscope at low magnification. Ethanol was found not to affect the ACF formation at any dose compared with the initiated-controls. Furthermore, ethanol did not alter colon epithelial cell proliferation. These data, obtained by analysis of a colon cancer surrogate marker lesion, indicate that ethanol lacks promotion activity for MeIQx-initiated rat colon carcinogenesis.     

Relationship between growth and plasma concentrations of ghrelin and growth hormone in juvenile beagle dogs

Although the release of growth hormone (GH) is known to be regulated mainly by GH-releasing hormone (GHRH) and somatostatin (SRIF) secreted from the hypothalamus, ghrelin also may be involved in GH release during juvenile period. We have examined plasma concentrations of acylated ghrelin, desacyl ghrelin, and GH in juvenile beagle dogs. Plasma acylated and desacyl ghrelin levels changed through aging; however, there was no closely correlation between ghrelin, body weight and circulating GH levels during juvenile period. The increase in body weight was essentially linear until 8 months of age, whereas plasma GH concentrations exhibited bimodal peaks for the meanwhile. The results suggest that ghrelin may not play internal cueing in GH secretion in juvenile beagle dogs.     

Cytological events in tomato leaves inoculated with conidia of <Emphasis Type="Italic">Blumeria graminis</Emphasis> f. sp. <Emphasis Type="Italic">hordei</Emphasis> and <Emphasis Type="Italic">Oidium neolycopersici</Emphasis> KTP-01

Leaves of tomato and barley were inoculated with conidia of Blumeria graminis f. sp. hordei race 1 (R1) or Oidium neolycopersici (KTP-01) to observe cytological responses in search of resistance to powdery mildew. Both conidia formed appressoria at similar rates on tomato or barley leaves, indicating that no resistance was expressed during the prepenetration stage of these fungi. On R1-inoculated tomato leaves, appressoria penetrated the papillae, but subsequent haustorium formation was inhibited by hypersensitive necrosis in the invaded epidermal cells. On the other hand, KTP-01 (pathogenic to tomato leaves) successfully developed functional haustoria in epidermal cells to elongate secondary hyphae, although the hyphal elongation from some conidia was later suppressed by delayed hypersensitive necrosis in some haustorium-harboring epidermal cells. Thus, the present study indicated that the resistance of tomato to powdery mildew fungi was associated with a hypersensitive response in invaded epidermal cells but not the prevention of fungal penetration through host papilla.     

Inhibitory influence of inorganic salts on banana postharvest pathogens and preliminary application to control crown rot

Lasiodiplodia theobromae, Thielaviopsis paradoxa, Colletotrichum musae, C. gloeosporioides, Fusarium verticillioides, and F. oxysporum were screened in vitro for sensitivity to Na₂CO₃, NaHCO₃, CaCl₂, NaCl, and NaClO. The spore germination of all pathogens was completely inhibited by Na₂CO₃ 4g/l, NaClO 5g/l, and NaHCO₃, CaCl₂, and NaCl 6g/l each. Dipping the bananas for 10–15min in these concentrations reduced the incidence of crown rot (compared with the untreated fruits) 17 days after harvest in fruits treated with NaClO by 67%, with NaHCO₃ by 62%, with NaCl by 38%, and with CaCl₂ by 33%. Na₂CO₃-treated fruits had the same incidence of crown rot as untreated fruits.     

Morphological analysis of corneal opacity in Shiba dog with GM1 gangliosidosis

GM1 gangliosidosis is one of the inherited metabolic lysosomal storage disorders characterized by neurological symptoms caused by beta-galactosidase deficiency and consequent accumulation of GM1 ganglioside in neuronal cells. Shiba dogs affected with GM1 gangliosidosis have been found to suffer from corneal opacity. In our morphological analysis, keratocyte enlargement was induced by abnormal intracellular accumulation of neutral carbohydrates, resulting in the loss of normal arrangement of collagen fibrils in the opaque cornea was found to be associated with the disorder. We therefore conclude that corneal opacity in this Shiba dog with GM1 gangliosidosis may be caused by neutral carbohydrate accumulation in lysosomes, swelling and dysfunction of keratocytes, and subsequent irregular arrangement of collagen fibrils in the corneal proper substance.     

Forestry expansion and land-use patterns in the Nelson Region,New Zealand

The expansion of plantation forestry in New Zealandduring the last century has altered the landscape and will continue to do so in the future. The implementation of recent resource management policy, the 1991 Resource Management Act (RMA), will also influence the impact of future plantation expansion on the landscape. It is necessary to analyze current land-use patterns in order to predict effects on future landscapes. This study analyzed the current land-use patterns of the Nelson region by examining the relationship between land-use and site conditions and by characterizing the distribution pattern of land-use depending on distance from the city. The distribution pattern was considered from an economic perspective, based on the Barlowe’s model of land use distribution. The relationship between the current land-use pattern and previous land management policy was also examined using the Land Use Capability. Consequently, in addition to the physical attributes of the land, the influence of land-use management policy was obvious. Thus the RMA will undoubtedly influence land-use changes in the future. It is therefore necessary to understand the factors determining changes in land-use patterns in conjunction with the district plan of the RMA to predict future changes in land-use.This revised version was published online in May 2005 with corrections to the Cover Date.     

Discoloration induced by Raffaelea quercivora isolates in Quercus serrata logs and its relation to phylogeny: a comparison among isolates with and without the Japanese oak wilt incidence including outside of Japan

Japanese oak wilt (JOW) has been prevalent in Japan since the late 1980s. Infections of the fungus, Raffaelea quercivora Kubono et Shin. Ito, which is transmitted by an ambrosia beetle [Platypus quercivorus (Murayama)], can cause JOW. Although R. quercivora, P. quercivorus, and oak trees are distributed in other Asia–Pacific countries, the incidence of JOW has not been reported outside Japan. In this study, we collected R. quercivora isolates from 5 Asian countries, including Japan, and compared their ability to induce sapwood discoloration by inoculating Q. serrata logs. The tangential widths of the discoloration in sapwoods inoculated with non-Japanese isolates were equivalent to or greater than those of the 2 Japanese isolates. This indicates that a lack of JOW incidence outside Japan is not because of the lowered ability of R. quercivora to spread discoloration compared with the Japanese isolates. Statistical analyses of the relationship between discoloration and phylogeny based on DNA sequences of actin and chitin synthase showed that the discoloration width was independent of phylogenetic relatedness among the isolates. To discuss why the occurrence of JOW has not been reported outside Japan, further studies (e.g., on host susceptibility and P. quercivorus aggression) throughout Asia are needed.     

A Spontaneous Oligodendroglioma in the Lumbar Portion of the Spinal Cord in a Young BrlHan:WIST@Jcl (GALAS) Rat

Oligodendroglioma is a rare tumor originating from oligodendrocytes found mainly in the cerebrum in aged rats. Only a few reports have shown spontaneous occurrence of this tumor in the spinal cord, and no report has mentioned its occurrence in young rats. We encountered a case of spontaneous oligodendroglioma in the lumbar portion of the spinal cord in a young (9 weeks old) female BrlHan:WIST@Jcl (GALAS) rat. Here we report the detailed histopathological and immunohistochemical characteristics of this case. No clinical signs, no gross lesions at necropsy, and no specific changes in hematology or blood biochemistry were observed. The tumor was located in the dorsal funiculus in the lumbar portion of the spinal cord and widely spread to the dorsal root nerve. The neoplastic cells showed a sheet-like growth pattern and had small round nuclei, clear cytoplasm and distinct cell borders that resulted in a honeycomb pattern. No mitotic figures or other histological lesions were observed. The neoplastic cells were positively stained for Olig2 and PCNA. The present case was considered to be a low-grade oligodendroglioma based on the histological and immunohistochemical features. To our knowledge, our case is considered to be extremely rare and the first report in a young rat.     

Activated Vitamin D3 and Pro-activated Vitamin D3 Attenuate Induction of Permanent Changes Caused by Neonatal Estrogen Exposure in the Mouse Vagina

Exposure of mice to a high dose of estrogens including diethylstilbestrol (DES) during the neonatal period modifies the developmental plan of the genital tract, which leads to various permanent changes in physiology, morphology and gene expression. These changes include development of an abnormal vaginal epithelium lined with hyperplastic mucinous cells accompanied by Tff1 gene expression in mice. Here, the influence of vitamin D on the direct effect of estrogen on the developing mouse vagina was examined. The mid-vagina of neonatal mice was cultured in a serum-free medium containing estradiol-17β (E₂) and various concentrations of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D) ex vivo and then was transplanted under the renal capsule of ovariectomized host mice for 35 days. Exposure to E₂ alone caused the vaginal tissue to develop estrogen-independent epithelial hyperplasia and to express TFF1 mRNA, while addition of a low nanomolar amount of 1,25(OH)₂D added at the same time as E₂ to the culture medium attenuated the effects of estrogen. Expression of vitamin D receptor was also evident in the neonatal mouse vagina. Interestingly, addition of 25-hydroxyvitamin D₃, a pro-activated form of vitamin D, at the micromolar level was found to be potent in disrupting the developmental effects of E₂, while cholecalciferol was not at least at the dose examined. Correspondingly, expression of Cyp27B1, a kidney-specific 25-hydroxyvitamin D hydroxylase, was evident in the neonatal mouse vagina when examined by RT-PCR. In addition, simultaneous administration of 1,25(OH)₂D successfully attenuated DES-induced ovary-independent hyperplasia in the vagina in neonatal mice in vivo. Thus, manipulation of vitamin D influenced the harmful effects of estrogens on mouse vaginal development.