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.     

The effects of dietary lipid sources and lecithin on the production of giant freshwater prawn <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis> larvae in the Mekong Delta region of Vietnam

The giant freshwater prawn, Macrobrachium rosenbergii, is cultured widely in the Mekong Delta region of Vietnam but it is often difficult or expensive for hatchery operators to purchase commercial diets used as a feeding supplement to Artemia nauplii. Therefore, in the present study, the effects of lipid sources and lecithin on the growth and survival rate of M. rosenbergii larvae were examined in order to develop suitable hand-prepared larval diets for seed production of M. rosenbergii in this area. Six egg custard diets consisting of various ratios of lipid (originating from soybean oil and squid oil) and lecithin were used for rearing Macrobrachium rosenbergii larvae. Treatments in which larvae were fed diets containing squid oil exhibited the highest body length and survival rates (7.14–7.43 mm and 51.1–68.1%, respectively), and differed significantly from other treatments (P<0.05). Use of dietary soybean oil yielded the lowest body length and survival rates (6.29–6.75 mm and 22.0–48.7%), respectively). The supplementation of dietary lecithin did not increase final body weight but did improve larval survival rates. The n-3 HUFA content of prawns fed dietary squid oil was higher than those of animals provided with other diets. These results indicated that the most appropriate diet for rearing M. rosenbergii larvae is the diet containing 3% squid oil and 1.5% lecithin.     

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.     

Near-infrared spectroscopy evaluated as a technique for estimating udder haemodynamics in the lactating cow

Near-infrared spectroscopy (NIRS) that requires few compact instruments is a non-invasive and continuous method of monitoring haemodynamics in living organs. To assess the feasibility of using NIRS in evaluating the udder haemodynamics in six dairy cows, a probe component consisting of a light-emitting diode and a phototransistor was attached to the left side of the udder surface. Real-time variation of tissue haemodynamics was analysed and the data were transferred to the computer by way of a radiotelemetry system. On induction of temporary congestion by applying pressure with the hand pressed firmly against the left milk vein for 20 s, concentration of oxyhaemoglobin decreased throughout the 20-s duration of congestion, and concentration of deoxyhaemoglobin increased. A surge in blood volume was also observed from the beginning of congestion, then the volume attenuated to baseline. The data demonstrated that the reading seen on the monitor reflects the real-time status of the mammary gland. NIRS shows promise as a useful approach to physiological studies.     

Molecular detection and characterization of Haemobartonella felis in domestic cats in Japan employing sequence-specific polymerase chain reaction (SS-PCR)

A novel PCR assay was developed in order to examine the prevalence of Haemobartonella felis (H. felis) in Japanese domestic cats and which was able to differentiate of the Ohio strain and the California strain of H. felis. Blood samples from a total of 21 cats suspected of having haemobartonellosis were examined employing a novel PCR assay and demonstrated positive results in 18 cats which was confirmed by cytological examination of blood smears. Four out of 18 positive cats (22%) were infected with the California strain, whilst the other 12 cats (67%) were infected with the Ohio strain and two animals (11%) were infected with both strains. As most of the cats with moderate to severe anemia were infected with the Ohio strain, it is suggested that the most prevalent strain of H. felis in Japanese domestic cats might be the Ohio strain. In the present study, it was thought that molecular detection and characterization of H. felis may provide valuable information regarding the severity and prognosis of this illness.     

Immunohistochemical and ultrastructural identification of Fusobacterium necrophorum subsp. necrophorum in bovine fatal necrotizing glossitis

A 37-day-old male Japanese black calf showing marked salivation and leucocytosis died and was examined the tissues histologically. Histological lesions were characterized by severe focal necrotic glossitis on the ventral side of the root of the tongue. Immunohistochemically, Fusobacterium necrophorum subsp. necrophorum antigen was detected in the necrotic tissues and its distribution corresponded to that of the gram-negative, nonsporeforming, long filamentous organisms. Ultrastructural similarities between the organism and F. necrophorum subsp. necrophorum, but not subsp. funduliforme were observed. These findings clearly demonstrated that the fatal necrotic glossitis was caused by F. necrophorum subsp. necrophorum. This is the first report of bovine fatal necrotizing glossitis with leucocytosis caused by F. necrophorum subsp. necrophorum infection, and this organism may be an important fatal pathogen in calves with glossal lesions.     

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.