Identification of anisotropic vibrational properties of Padauk wood with interlocked grain

Grain deviations and high extractives content are common features of many tropical woods. This study aimed at clarifying their respective impact on vibrational properties, referring to African Padauk (Pterocarpus soyauxii Taub.), a species selected for its interlocked grain, high extractives content and uses in xylophones. Specimens were cut parallel to the trunk axis (L), and local variations in grain angle (GA), microfibril angle (MFA), specific Young’s modulus (E′ _L /ρ, where ρ stands for the density) and damping coefficient (tanδ_L) were measured. GA dependence was analysed by a mechanical model which allowed to identify the specific Young’s modulus (E′₃/ρ) and shear modulus (G′/ρ) along the grain (3) as well as their corresponding damping coefficients (tanδ₃, tanδ_G). This analysis was done for native and then for extracted wood. Interlocked grain resulted in 0–25° GA and in variations of a factor 2 in E′_L/ρ and tanδ_L. Along the grain, Padauk wood was characterized, when compared to typical hardwoods, by a somewhat lower E′₃/ρ and elastic anisotropy (E′/G′), due to a wide microfibril angle plus a small weight effect of extracts, and a very low tanδ₃ and moderate damping anisotropy (tanδ_G/tanδ₃). Extraction affected mechanical parameters in the order: tanδ₃ ≈ tanδ_G > G′/ρ > > E′₃/ρ. That is, extractives’ effects were nearly isotropic on damping but clearly anisotropic on storage moduli.     

Population model of Rana japonica crossing agricultural concrete canals: evaluating population conservation by improving the migration routes of frogs

Agricultural canals with deep concrete walls are commonly installed in paddy field areas following land consolidation projects in Japan. Such canals create a critical migration barrier for frogs, as escape is not possible after falling in. Hence, countermeasures that allow migrating frogs to cross agricultural canals, such as lid structures to prevent frogs from falling in or the creation of partial slopes to allow escape, have been developed to conserve endangered frog populations. The objective of this study was to design a method for evaluating the population viability of the endangered Japanese Brown Frog, Rana japonica, following the implementation of countermeasures. Two types of model simulations were examined: (1) a ??basic model,?? based on an age-structured model and (2) a ??crossing model,?? to evaluate migrating frogs crossing canals. Parameters, such as survival rate and fecundity, were estimated from field observation data of age-dependent population fluctuations. Comparison of a basic model simulation with the field observation data suggests model validation. The crossing model simulation, which had an initial population of 1,000 individuals, showed that a crossing proportion of greater than 30?C40% would achieve 95% population viability after 5?years. The simulation also showed that a crossing proportion of over 80% would also achieve 95% population viability after 40?years. These results indicate that frog survival during the migration period is insured, as long as no additional countermeasures are necessary after installation.     

Spontaneous Mammary Adenocarcinoma in a Twelve-week-old Female Sprague-Dawley Rat

Spontaneous mammary adenocarcinoma was observed in a 12-week-old female SD rat. A movable mass in the right cervical region was found at 11 weeks of age, and the rat was sacrificed the following week. The mass was located in the vicinity of the right salivary gland and measured 38 mm × 26 mm × 16 mm in gross size. It was a firm whitish mass, with a cut surface that was also whitish in appearance. Histopathologically, neoplastic cells formed glandular structures that contained secreted eosinophilic material. Ultrastructurally, similar secreted material and lipid droplets were in the cytoplasm of the neoplastic cells. Immunohistochemically, the neoplastic cells were positive for cytokeratin 8, cytokeratin 18 and estrogen receptor α. Based on these findings, the tumor was diagnosed as a mammary gland adenocarcinoma, and we therefore conclude that this tumor type can occur spontaneously in female SD rats as young as 12 weeks of age.     

Examination of the 16S-23S rRNA intergenic spacer sequences of 'Candidatus Mycoplasma haemobos' and Mycoplasma haemofelis

The intergenic spacer region between the 16S and 23S rRNA genes of mycoplasmas has been used for a genetic marker for identification of the species. Here we show the intergenic spacer regions of two hemotropic mycoplasmas, Mycoplasma haemofelis and 'Candidatus Mycoplasma haemobos (synonym: 'C. M. haemobovis')' are also useful for classification of this particular group of mycoplasms. The spacer region of M. haemofelis and `C. M. haemobos' consisted of 209 and 210 base pairs, respectively, and both lacked the spacer tRNA genes. Phylogenetic analysis suggested a monophyletic relationship among hemoplasmas and M. fastidiosum. A hypothetical secondary structure predicted in the spacer regions tentatively assigned the boxA and boxB motifs peculiar to the members of the genus Mycoplasma. M. haemofelis and 'C. M. haemobos' possessed a stem-loop structure in common, despite the presence of a palindromic nucleotide substitution in the stem region.     

Perivertebral B-Cell Lymphoma in a Queensland Koala (Phascolarctos cinereus adustus) with Paralytic Symptoms in the Hind Limbs

A male Queensland koala (Phascolarctos cinereus adustus) at Kanazawa Zoological Gardens (Kanagawa, Japan) exhibited paralytic symptoms in the hind limbs. Computed tomography and magnetic resonance imaging revealed a mass on the left ventral side of the 11th to 13th thoracic vertebrae, and the presence of myelitis or edema in the spinal cord. The koala was under anesthesia during the examination and suddenly developed ventricular fibrillation and died. Necropsy revealed a firm flat ovoid hemorrhagic mass on the vertebrae. Following a microscopic examination including immunohistochemistry, the perivertebral mass was diagnosed as B cell lymphoma. Therefore, neoplastic cell infiltration into the spinal cord may cause paralytic symptoms in the hind limbs.     

Xenotransplantation of porcine pancreatic endocrine cells to total pancreatectomized dogs

Xenotransplantation of porcine pancreatic endocrine (PE) cells in a diffusion chamber, a bioartificial endocrine pancreas (Bio-AEP), was conducted to total pancreatectomized dogs. Six pancreatectomized dogs were divided into two groups of 3 dogs each. In three dogs of the control group, exogenous insulin was administered twice a day for 30 weeks to maintain fasting blood glucose (FBG) levels within the normal range. The remaining three dogs were implanted with Bio-AEPs (implantation group), in addition to daily insulin administration. In the implantation group, Bio-AEPs containing 1.3 to 1.8 x 10(7) cells per kg of body weight of the recipient were implanted without fixation into the abdominal cavity. In the control group, exogenous insulin requirements did not decrease during the experimental period, whereas it significantly decreased for a certain period (3, 11, 17 weeks) after implantation in all implanted dogs. In the implantation group, laparotomy was performed after FBG and the exogenous insulin requirement increased again and Bio-AEPs were removed. Two Bio-AEPs were completely destroyed, and the remaining one was encapsulated by thin fibrous tissue. In this dog, effusion was present within the capsule, but the Bio-AEP was not destroyed. Histopathologically, the necrosis, presumably caused by hypoxia, of the PE-cells was observed on transmission electron microscopy. In conclusion, Bio-AEP could function for a certain period after implantation in this study. However, more preclinical researches should be needed to apply this technique for the treatment of diabetic dogs.     

Functional Characterization of Citrus Polygalacturonase-inhibiting Protein

A cDNA encoding a polygalacturonase-inhibiting protein gene (SaiPGIPA) was identified from the citrus cultivar Sainumphung (Citrus sp.), one of the most popular cultivars in northern Thailand. SaiPGIPA was expressed in Escherichia coli cells, and the functional properties of citrus PGIP were analyzed. The PGIP fusion protein inhibited by a maximum of about 60% of the endopolygalacturonase activity, and a mixture of the PGIP and fungal endopoly-galacturonase released oligogalacturonides from polygalacturonic acid. The mixture containing the oligogalactur-onides, endopolygalacturonase and PGIP induced expression of the PGIP gene and a chalcone synthase gene in citrus leaves. The mixture also induced resistance in cucumber leaves against Colletotrichum lagenarium. Received 5 September 2001/ Accepted in revised form 20 November 2001