Morphological study on the stomach of the lesser mouse deer (Tragulus javanicus) with special reference to the internal surface.

The stomach of the lesser mouse deer (Tragulus javanicus) was observed macroscopically. It consisted of only three compartments, rumen, reticulum and abomasum without omasum. The rumen was S-shaped with large ventral and caudoventral blind sacs and the reticulum was larger than the abomasum. Internally, the rumen was covered with numerous ruminal papillae even on the pillars and the ruminoreticular fold. These papillae were leaf- or tongue-like shaped and varied in size and density. The reticulum had honey-combed crests and the secondary crests were found rarely. The lips of the reticular groove were prominent and more developed in the aboral part than in the oral one. A sac-like transition zone, which had more prominent mucosal folds than had the floor of the reticular groove, was observed between the caudal end of the reticular groove and the abomasum. Mucosal folds of the abomasum were spiral, low but rather thick. These findings were discussed in view of comparison with other ruminants and of possible functional implications.     

Immunohistochemical evaluation of a malignant phecochromocytoma in a wolfdog

A malignant pheochromocytoma with multiple metastases was diagnosed in a 7-year-old male wolfdog that resulted from a cross between an eastern timber wolf (Canis lupus lycaon) and an Alaskan malamute. A yellowish white neoplastic mass approximately 10 cm diameter was found in the right adrenal gland. The neoplasm penetrated through the wall of the caudal vena cava. A diagnosis of pheochromocytoma was established by histopathologic and immunohistochemical procedures. Immunohistochemically, the neoplastic cells expressed chromogranin A, substance P, synaptophysin, Leu-7, protein gene product 9.5, methionine-enkephalin, S100 protein, and galanin. Multiple metastatic tumors were found in the kidneys, spleen, lungs, heart, and liver.     

Immunohistochemical localization of inhibin subunits in the testis of the bull

The differential localization of the inhibin beta subunits betaA and betaB in the testis of adult bull was studied using specific monoclonal and polyclonal primary antibodies. Inhibin betaA- and betaB-subunits were localized only in the Sertoli cells. The inhibin betaA-subunit was observed in the cytoplasm while the betaB-subunit was localized in the nucleus. No specific findings depending on spermatogenic stages were observed among the seminiferous tubules. Moreover, the inhibin alpha-subunit was not detected in the testis of the bulls. In addition, no inhibin subunits were detected in the Leydig cells and spermatogenic cells. These findings indicate the presence of betaA- and betaB-subunits in the bull, which may suggest a possibility that activin is produced and/or stored in the Sertoli cells and regulates spermatogenesis in an autocrine/paracrine manner. Moreover, the inhibin betaB-subunit may be produced in the nucleus but the functional meaning of this is not yet clear.     

Hepatocyte growth factor transduces different intracellular signals in aortic and umbilical venous endothelial cells

Endothelial cells are important for maintenance of vascular integrity by producing a variety of bioactive molecules such as nitric oxide (NO). Recent evidence has suggested that there are some differences in characteristics between endothelial cells from different origins. Here we examined responses of two typical endothelial cells to hepatocyte growth factor (HGF), which induces endothelium-dependent relaxation of microvessels. Stimulation of human umbilical vein endothelial cells (HUVEC) and bovine aortic endothelial cells (BAEC) with HGF increased endothelial NO synthase activity, accompanied with an increase of activity-related site-specific phosphorylation of protein kinase B/Akt. However, HGF stimulated phosphorylation of p38 mitogen-activated protein kinase (MAPK) only in HUVEC, but not in BAEC, while it induced phosphorylation of p44/p42 MAPK in both cells. These results suggest that HGF transduces different intracellular signals between aortic and umbilical venous endothelial cells, and that the differences might represent divergent endothelial responses to growth factors, especially those that activate receptor-tyrosine kinases.     

Experimental and clinical studies on plasma leptin in obese dogs

Leptin is a protein synthesized and secreted primarily by adipocytes, and the circulating leptin concentration is elevated in obese humans and rodents. Recently, we have established a sandwich enzyme-linked immunosorbent assay for canine leptin. In the present study, plasma leptin concentrations were measured in experimentally developed obese beagles and in clinically obese dogs. When 5 male beagles were given a high-energy diet for 3 months, all of them became obese and the plasma leptin concentration significantly increased from 2.4+/-1.2 to 4.9+/-0.9 ng/ml, positively correlating with body fat content estimated by the deuterium oxide dilution method (r=0.87). The leptin concentrations of plasma samples collected from 59 dogs in veterinary practices were compared with their body condition scores (BCS). The plasma leptin concentrations of obese dogs were 9.7+/-0.7 and 12.3+/-1.5 ng/ml at BCS=4 and BCS=5, respectively, which were significantly higher than those of optimal (BCS=3) dogs (2.7+/-0.3 ng/ml). There was no significant effect of sex and breed. A weak positive correlation (r=0.37) was found between the plasma leptin concentration and age, probably due to the lesser content of visceral fat in puppies younger than 1 year old. These results indicate that plasma leptin is a good index of adiposity in dogs regardless of breed, age and sex, and may be useful for quantitative assessment of obesity in small animal practice.     

An immunohistochemical study of endocrine cells in the abomasum of vagotomized calf

The effect of thoraco-vagotomy on the distribution and frequency of chromogranin-, serotonin-, somatostatin- and gastrin-immunoreactive cells in the abomasum of the calf were investigated by immunohistochemistry. Calves were vagotomized at 1 week old and sampled 2 and 4 weeks later. The endocrine cells generally decreased in number in vagotomized calves as compared to non-operated control calves. However, the detailed responses of endocrine cells to vagotomy varied depending on the endocrine cell type, region of gastric mucosa, and period after vagotomy. The present result suggests that the vagus nerve has an influence on the intrinsic regulatory system by endocrine cell control in the ruminant abomasum.     

Immunohistochemical Colocalization of Serotonin, Substance P and Met-enkephalin-Arg6-Gly7-Leu8 in the Endocrine Cells of the Ruminant Duodenum

The duodenum of various ruminants was examined by immunohistochetnical staining for serotonin, substance P and Metenkephalin-Arg⁶-Gly⁷-Leu⁸ (MENK8). Serotonin- and substance P-immunoreactive endocrine cells were detected in samples from cow, calf, sheep, goat, and barbary sheep. MENK8-immunoreactive endocrine cells were detected exclusively in samples from cow and calf. Substance P and MENK8 immunoreactivity was found in serotonin-immunoreactive endocrine cells of cattle. Substance P- and MENK8-immunoreactive nervous elements were detected in all ruminants examined. The present results suggest that the expression and/or the mechanism that controls the expression of each peptide might differ between endocrine cells and nerve cells and might also depend on animal species.     

Effects of carbon and nitrogen amendment on soil carbon and nitrogen mineralization in volcanic immature soil in southern Kyushu,Japan

Soil N mineralization is affected by microbial biomass and respiration, which are limited by available C and N. To examine the relationship between C and N for soil microbial dynamics and N dynamics, we conducted long-term laboratory incubation (150 days) after C and N amendment and measured changes in C and N mineralization, microbial biomass C, and dissolved C and N throughout the incubation period. The study soil was volcanic immature soil from the southern part of Japan, which contains lower C and N compared with other Japanese forest soils. Despite this, the area is covered by well-developed natural and plantation forests. Carbon amendment resulted in an increase in both microbial biomass and respiration, and net N mineralization decreased, probably due to increasing microbial immobilization. In contrast, N amendment resulted in a decrease in microbial respiration and an increase in net N mineralization, possibly due to decreased immobilization by microbes. Amendment of both C and N simultaneously did not affect microbial biomass and respiration, although net N mineralization was slightly increased. The results suggested that inhibitory effect on microbial respiration by N amendment should be reduced if carbon availability is higher. Thus, soil available C may limit microbial biomass and respiration in this volcanic immature soil. Even in immature soil where C and N substrate is low, soil C, such as plant root exudates and materials from above- and belowground dead organisms, might help to maintain microbial activity and N mineralization in this study site.