Journal of Veterinary Medical Science
Online ISSN : 1347-7439
Print ISSN : 0916-7250
ISSN-L : 0916-7250
Volume 70, Issue 3
March
Displaying 1-22 of 22 articles from this issue
Anatomy
  • Misato KASEDA, Michiko NAKAMURA, Nobutsune ICHIHARA, Toshiyuki HAYAKAW ...
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 217-222
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    The musculature of the hip and thigh in the orangutan has been described previously. Anatomically, there are various descriptions among primates in those structures, in particular, the relationship between M. biceps femoris and M. gluteus maximus, their derivatives, and the muscle segment. However, a detailed innervation system to this ischiofemoral part has not been described, thus there is still uncertainty as to with which muscle it is associated. In this analysis, we examined the gross anatomy of the hip and thigh muscles of the orangutan and chimpanzee, including their innervation. Also, a comparison was made with documented data of other primates. As a result of these observations, it was found that the ischiofemoral part in the orangutan is innervated by the same sciatic nerve branch (the common peroneal nerve) as the long head of M. biceps femoris, but not by the same nerve as M. gluteus maximus. Therefore, the ischiofemoral part is appropriately considered as a part of the long head of M. biceps femoris. It appears that this morphologic feature is an adjustment to the arboreal life of the orangutan. The development of the flexor complex of the thigh is necessary for this arboreal adaptation, resulting in a unique musculature of M. biceps femoris in the orangutan.
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  • Tetsurou INAMOTO, Yuko KAWATA, Wang-Mei QI, Kenkichi YAMAMOTO, Katsuhi ...
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 235-241
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    The ultrastructure of epithelial responses against the membrane adhesion of indigenous bacteria was investigated in the follicle-associated epithelium (FAE) of rat small intestine. The most frequent adherence of the various morphological types of bacteria to the epithelial membranes was found at the apex of the FAE. The attachment sites were deeply invaginated, and their bottoms were deformed into a sharp cone shape. Four layers with different electron densities were formed just beneath the apical membranes by microfilaments which surrounded the invaginations. The electron density of each layer was gradually decreased as being apart from the invaginations. The extremities of some bacteria in the invaginations were deformed into sharpened shapes. The cell walls of the extremities of the bacteria were occasionally dissolved in the invaginations, and their cytoplasms were slightly swollen with low electron densities. In some invaginations, the attached bacteria were eliminated to leave their fragments such as filamentous debris and a part of cell walls. Finally these remnants disappeared completely. When the bacterial colonies existed in the middle region of the FAE, the attachment of bacteria resulted in the engulfment of bacteria by M cells. The degenerated bacteria whose cytoplasmic matrices were separated into high electron dense materials and cleared materials were occasionally engulfed by ordinary microvillous columnar epithelial cells or goblet cells throughout the FAE. These findings suggest that the epithelial cells reject the attachment of live indigenous bacteria and that the M cells absorb indigenous bacteria in rat Peyer's patches.
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  • Yoshio YAMAMOTO, Ryota ISHIKAWA, Katsuhiko OMOE, Norie YOSHIKAWA, Misu ...
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 265-271
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    The inwardly rectifying K+ channels, Kir1.1, Kir2.3 and Kir4.1-Kir5.1, are the candidate chemosensory molecules for CO2/H+. We determined the mRNA expression and immunohistochemical localization of these channels in the medulla oblongata of the rat. RT-PCR analysis revealed mRNAs of Kir1.1, Kir2.3, Kir4.1 and Kir5.1 were detected in the medulla. The immunoreactivities for Kir1.1, Kir2.3, Kir4.1, and Kir5.1 were observed in the medulla, and immunolabeling pattern was varied by the subunit. Immunoreactivities for Kir1.1 and Kir2.3 were observed in the nerve cell bodies and glial cells both in the chemosensory areas [nucleus tractus solitarius (NTS), nucleus raphe obscurus (RO), pre-Bötzinger complex (PreBötC)] and non-chemosensory area [hypoglossal nucleus (XII), inferior olive nucleus (IO)]. Kir4.1 immunoreactivity was observed in the glial cells and neuropil, especially in XII and IO. Kir5.1 immunoreactivity was observed in the nerve cell bodies in the XII, RO, and PreBötC, but not in the NTS or IO. In the NTS, a dense network of varicose nerve fibers showed immunoreactivity for Kir5.1. Our findings suggest that Kir channels may not act specific to the central chemoreception, but regulate the ionic properties of cellular membranes in various neurons and glial cells.
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  • In Koo HWANG, Yeo Sung YOON, Ki-Yeon YOO, Hua LI, Jung Hoon CHOI, Dae ...
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 273-277
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    Reactive oxygen species have been long associated with oxidative stress relevant to many pathological damages. In brain, 4-hydroxy-2E-nonenal (HNE), a major cytotoxic end product of lipid peroxidation, is produced. In contrast, superoxide dismutase (SOD), one of the major antioxidant enzymes, protects neurons from oxidative stress. The aim of this study is to observe differences in the distribution of HNE and Cu,Zn-superoxide dismutase (SOD1) in the hippocampal CA1 region of adult (2-3 years of age) and aged (10-12 years of age) dogs. The HNE immunoreactivity and protein level in the CA1 region were significantly high in the aged dogs compared to those in the adult dogs. SOD1 immunoreactivity and its protein level were also higher in the aged dogs than those in the adult dogs. However, there were not significant differences in NeuN (a neuron-specific soluble nuclear antigen) immunoreactivity in CA1 neurons between the adult and aged dogs. These differences may be associated with oxidative stress in aged dogs compared to that in adult dogs.
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  • Nao KAMEMORI, Takashi TAKEUCHI, Akihiko SUGIYAMA, Mariko MIYABAYASHI, ...
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 313-315
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    The transportation of intravenously administered bovine lactoferrin (bLF) into the cerebrospinal fluid (CSF) was immunohistochemically investigated in adult rats. Administered bLF was detected in the vesicular membranes of endothelial cells in cerebral blood vessels 10 min after the infusion. Numerous immunoreactive small vesicles were also detected at the ependymal cells in the choroid plexus. Moreover, the bLF concentration in the CSF was significantly increased at 1-2 hr after the intravenous infusion of bLF (10 or 30 mg/kg). These findings clearly demonstrate that LF is possibly transported into the brain matter even in adult animals.
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Biochemistry
Immunology
  • Isao OTANI, Kohei OHTA, Akira ISHIKAWA, Takeki YAMADA, Tsuyoshi ISHINA ...
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 285-287
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    Lymphocyte subsets in canine umbilical cord blood were flow cytometrically analyzed and compared with those of the dams' peripheral blood. The proportion of CD3+ T lymphocytes, CD21+CD3- B lymphocytes, and CD3-CD21- non-T non-B lymphocytes in umbilical cord blood was 52.9%, 30.4%, and 16.7%, respectively. T lymphocyte/B lymphocyte ratio was significantly lower in the umbilical cord blood than in the dams' peripheral blood (2.1 ± 1.4 versus 11.0 ± 8.1, P < 0.001). In contrast, CD4+ lymphocyte/CD8+ lymphocyte ratio was significantly higher in the umbilical cord blood than in the dams' peripheral blood (7.6 ± 2.2 versus 1.8 ± 0.6, P<0.001). These findings clarified the phenotypic characters of canine umbilical cord blood lymphocytes.
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Internal Medicine
  • Yasuo MORITOMO, Kenichi SHIMOJO, Keiko MIYADERA, Maryam KHALAJ, Yuka A ...
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 293-296
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    A coagulopathy with subcutaneous bleeding and muscular or peritracheal/periesophageal bleeding occurred in two male Japanese Brown calves of the same dam. One of the affected calves died three days after the onset of bleeding and the other survived normally until being slaughtered despite once suffering from subcutaneous hematoma. Hemostatic tests of the latter case showed prolonged activated partial thromboplastin time (APTT), and severely reduced factor VIII activity. In addition, von Willebrand factor activity, determined by the human platelet aggregation test, was within the normal range; therefore, the calf was diagnosed with hemophilia A. These are the first bovine cases of hemophilia A definitely diagnosed clinicopathologically.
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  • Yasunori OHBA, Masaki TAKASU, Naohito NISHII, Eri TAKEDA, Sadatoshi MA ...
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 297-299
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    Using a DNA-based diagnostic test for factor XI deficiency in Japanese black cattle, we surveyed 123 cattle (42 sires and 81 dams) in Gifu and Hyogo prefectures, and calculated gene frequencies. In sires, we drew up the pedigree network of the cattle with the factor XI deficiency. Results showed that the mutated allele of factor XI deficiency was retroactive in at least 6 or more generations of sires. Frequencies of the mutant gene were higher at 26.4% in total, and at 33.3% in sires. All 7 cattle with the homozygote of mutated allele were clinically normal, and showed no bleeding episodes. The mutated allele of factor XI deficiency might be widespread among Japanese black cattle.
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  • Tatsuhiko MACHIDA, Eiji UCHIDA, Kazuya MATSUDA, Kazuko HIRAYAMA, Kengo ...
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 317-320
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    A 12-year-old, intact female beagle exhibited symptoms of polyuria-polydipsia and hyperorexia for two months. Blood tests showed elevated asparate aminotransferase, alanine aminotransferase, alkaline phosphatase and creatine kinase levels, as well as marked hypokalemia. The results of adrenocorticotropic hormone stimulation test showed elevated cortisol, aldosterone and corticosterone concentrations. Abdominal ultrasonography confirmed a mass in the left adrenal gland. Masses were also seen in the liver and caudal vena cava. Diagnosis was a tumor of the adrenal cortex with metastases. Trilostane administration was initiated. The dog initially showed improved demeanor as a result of regulating hormone secretion. However, after 88 days, the dog weakened rapidly, before dying on the 117th day. Pathological findings confirmed a diagnosis of adrenocortical carcinoma.
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  • Masayuki KOHIRUIMAKI, Hiromichi OHTSUKA, Erika TANAMI, Madoka KITAGAWA ...
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 321-323
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    The leukocyte populations of periparturient dairy cows were analyzed after administration of active egg white/Clostridium butyricum Miyairi additive. Sixty-eight Holstein milking cows were divided into 3 groups. Group A was administered active egg white product (AEWP)/Clostridium butyricum Miyairi 588 (Miyairi 588) additive (n=23). Group B was administered Miyairi 588 only (n=23), and Group C was the control group (n=22). The challenged groups were administered 100 g of AEWP + Miyairi 588, or Miyairi 588 alone, daily for 60 days from 1 month before until 1 month after paturition. Blood samples were collected from all groups three times (1 month before, 1 week after and 1 month after parturition) for analysis of the peripheral leukocyte population. The results showed significantly higher numbers of CD4+ cells in Group A compared with Group C 1 week after paturition. AEWP/Miyairi 588 additive may enhance the number of CD4+ T cells in periparturient dairy cows.
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Pathology
  • Kiyokazu OZAKI, Yutaka NAKAHARA, Isao NARAMA
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 289-291
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    A dog presented with hematuria, and two small polypoid masses were detected in the urinary bladder. Histopathologically, the masses were located in the mucosal or submucosal layer. That tissue consisted of a random proliferation of spindle-shaped, round and pleomorphic cells with single or multiple large atypical nuclei and abundant cytoplasm, and eosinophil infiltration. These large cells were confirmed by immunohistochemical staining as fibroblasts, myofibroblasts and macrophages. Mitotic figure was rarely seen. These masses were diagnosed as eosinophilic polypoid cystitis with pseudosarcomatous proliferative tissue, since they consisted of a wide variety of cells and showed low growth activity.
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  • Atsushi KAWABATA, Kazuhide NAKAGAKI, Motonobu YOSHIDA, Kinji SHIROTA
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 301-303
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    Five raccoon dogs (Nyctereutes procyonoides) and two domestic dogs (Canis familiaris) were subcutaneously infected with 100 infective larvae (L3) of Dirofilaria immitis. Two and five worms, respectively, were collected from two of three raccoon dogs. Villous endarteritis was found in the raccoon dog with five worms and two dogs at 116 days after infection. The number of recovered worms in the raccoon dogs was significantly smaller than that of the domestic dogs having 22 and 29 worms, while histopathological features and the severity of the lesions in the raccoon dogs were similar to those in the domestic dogs. The vascular lesions in two chronically-infected raccoon dogs turned into much severe at 565 and 590 days after inoculation.
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  • Manabu YAMADA, Rie KOZAKURA, Yoshihiro KAKU, Kikuyasu NAKAMURA, Yu YAM ...
    Article type: NOTE
    2008 Volume 70 Issue 3 Pages 305-308
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    A distribution of porcine teschovirus (PTV) antigens in pigs naturally infected with PTV is presented using the method of immunohistochemical examination. In the nervous system, PTV antigens were found in the cytoplasm of neuronal cells and glial cells distributed in the spinal ventral horn and brain stem, and also in the cytoplasm of ganglion cells in the spinal ganglion. No antigens were seen in the cerebral hemisphere. In the nervous system, the distribution of PTV antigens was consistent with lesions characteristic of nonsuppurative encephalomyelitis. In the other examined organ, PTV antigens were observed in bronchiolar epithelial cells in the lung, hepatocytes in the liver, epithelial cells in the tonsils and the myenteric nerve plexus in the small and large intestine.
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Public Health
  • Itaru SATO, Shuji TSUDA
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 213-216
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    Isotopic dilution with stable zinc and chelation with DTPA are recommended for removal of radioactive zinc from the body; however, it is unclear which method is more effective. In the present study, the efficacies of these methods were compared in order to determine which treatment should be selected in case of internal contamination with radioactive zinc. Intraperitoneal administration of stable zinc dose-dependently removed 65Zn from the mouse body. However, the dose could not be increased above 3 mg/kg due to its toxicity. Oral administration of zinc was less effective than intraperitoneal administration at the same dose. Our results suggest that the recommended dose of stable zinc (2-3 mg/kg, p.o.) has little efficacy. The efficacies of Ca-DTPA and Zn-DTPA were strongly dependent on the elapsed time after 65Zn exposure. Zn-DTPA was more effective than Ca-DTPA, and its recommended dose (30 μmol/kg) significantly removed 65Zn. Therefore, chelation therapy with Zn-DTPA should be started as soon as possible after internal contamination with radiozinc.
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  • Keiko KATO, Yasushi SAWADA
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 251-254
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    The tonsils of cattle, including palatine tonsils, pharyngeal tonsils, tubal tonsils and lingual tonsils, are designated as specified risk materials (SRM). However, the detailed distribution of lingual tonsils in cattle is unknown. We therefore histologically examined their distribution in 198 tongue specimens from cattle. The examinations confirmed that the presence of lingual tonsils was limited to the tissue of the lamina propria on the dorsal and lateral aspects of the tongue, not reaching the muscular layer below. More than 90% of the lingual tonsils were located between the distribution center of the vallate papillae and the radix linguae (root of the tongue). However, they were also found in the area extending from the lingual torus to the rostral-most vallate papilla in an individual, suggesting that the complete removal of the lingual tonsils requires elimination of the lamina propria extending from the lingual torus to the radix linguae.
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Surgery
  • Yumi KONDO, Satoru MATSUNAGA, Manabu MOCHIZUKI, Tsuyoshi KADOSAWA, Tak ...
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 207-212
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    To evaluate the efficacy of clinical staging based on computed tomography (CT) imaging over the World Health Organization (WHO) staging system based on radiography for nasal tumors in dogs, a retrospective study was conducted. This study used 112 dogs that had nasal tumors; they had undergone radiography and CT and had been histologically confirmed as having nasal tumors. Among 112 dogs, 85 (75.9%) were diagnosed as adenocarcinoma. Then they were analyzed for survival time according to each staging system. More than 70% of the patients with adenocarcinoma were classified as having WHO stage III. The patients classified under WHO stage II tended to survive longer than those classified under WHO stage III. Dogs classified under WHO stage III were further grouped into CT stages III and IV, and CT stage III patients had a significantly longer survival time than CT stage IV patients. In addition, patients treated with a combination of surgery and radiation had a significantly longer survival time than the patients who did not receive any treatment in CT stage III. On the other hand, different treatment modalities did not show a significant difference in the survival time of CT stage IV dogs. The results suggest that WHO stage III dogs may have various levels of tumor progression, indicating that the CT staging system may be more accurate than the WHO staging system.
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  • Kazuaki TAKASHIMA, Aiko SODA, Ryou TANAKA, Yoshihisa YAMANE
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 279-283
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    This study evaluated the long-term clinical performance of newly developed porcine bioprosthetic valves cross-linked with glutaraldehyde and polyepoxy compound for mitral valve replacement (MVR) in dogs. Five beagle dogs underwent MVR using the porcine bioprosthetic valves during cardiopulmonary bypass. Antithrombotic drugs were administered only for one month after MVR. Six months after MVR, transvalvular regurgitation was not observed in all dogs, paravalvular leakage was seen only in one dog. Twelve months after MVR, mild transvalvular regurgitations were observed in two dogs. Although diastolic atrioventricular pressure gradient was increased gradually, no significant differences were observed. Pressure half-time and valve area were within normal ranges as the bioprosthetic value. There was no clinical symptom of the thrombosis and the thrombogenesis was not observed in the porcine bioprosthetic valve and the annulus in all dogs for twelve months after MVR. The clinical findings suggest that antithrombogenicity of the valves were maintained, though the duability might not be enough in the long-term period.
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Theriogenology
  • Akihiro IWAKUMA, Tomonaga NARAHASHI, Go KITAHARA, Masahito OHKUBO, Shu ...
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 243-249
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    Reproductive performance of two types of timed artificial insemination (TAI) protocols with or without intravaginal progesterone insert (CIDR) was investigated in a commercial herd of Holstein heifers. A total of seventy-four heifers with 14.4 months of age were allocated to two groups; Ovsynch (n=44) and estradiol benzoate (EB) used Heatsynch (EB-Heatsynch, n=30), and each group was additionally divided into two subgroups with CIDR insertion from day 0 to 7 (n=36) and without CIDR group (n=38). Blood was collected for progesterone (P4) analysis and ovarian finding was monitored with ultrasonography. Heifers in CIDR-treated group resulted in higher pregnancy rate as compared to No-CIDR-treated group (63.9% vs 21.1%, P<0.01). Heifers with functional corpus luteum (CL) on day 0 resulted in significantly higher pregnancy rate in CIDR-treated group than No-CIDR-treated group (day 0: 67.9% vs 13.0%, P<0.01). CIDR insertion suppressed the intermediate ovulation during the first 7 days and the period from the second GnRH or EB administration to TAI as compared to No-CIDR-treated group (first 7 days: 33.3% vs. 52.6%; P<0.05, before TAI: 11.1% vs. 37.0%; P<0.05). In conclusion, the selected TAI protocols with CIDR provided acceptable pregnancy rate and contributed to the economical improvement by shortening the average age of first calving approximately for 2.5 months as compared to the previous management without TAI protocols.
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Toxicology
  • Nobuo SASAKI, Noriaki SAKAI, Yoshinori IKENAKA, Tomomi KAMIYA, Min HEE ...
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 223-226
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    Furazolidone (FZ), one of the nitrofuran fungicides, is used as a veterinary medicine in the Middle and Far Eastern countries. In this study, FZ (125 mg/kg) was administered orally to Wistar rats for 3 days. Results of the Ames test using the S-9 fraction of rats treated with FZ showed a significant increase in the number of revertant colonies. Western blot analysis of hepatic CYP isozymes induced by FZ, revealed a remarkable induction of CYP1A1 apoprotein, but CYP1A2 and CYP2E1 apoproteins were not altered. In addition, the expression of CYP1A1 mRNA level in rats treated with FZ by RT-PCR was significantly enhanced by FZ treatment. We concluded that FZ is apparently mutagenic and induces transcription of the CYP1A1 isozyme, which metabolically activates numerous promutagens, in hepatocytes.
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  • Noriko TADA, Aya NAKAO, Hidenobu HOSHI, Masahiro SAKA, Yoichi KAMATA
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 227-234
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    Vitellogenin (VTG), a biomarker for environmental estrogenic pollution, can be detected in the bloodstream of oviparous animals before morphological and functional abnormalities appear due to exposure to environmental estrogens. Reports observing VTG in turtles have been limited. We therefore cloned and sequenced a partial cDNA of VTG in Reeves' pond turtle, Chinemys reevesii. The cloned cDNA fragment possessed the start codon and 2,229 bp, encoding 743 amino acid residues. A sequence of deduced amino acid from the cDNA did not contain a high serine content, such as that which exists in phosvitin. Two N-glycosylation sites were found in the sequence. The sequence was compared to those of two birds (chicken and herring gull), one amphibian (Xenopus), and five fishes (carp, zebrafish, eel, haddock, and red seabream). The C. reevesii VTG was similar to that of herring gull (78%, value of positives), chicken (76%), Xenopus (69%), eel (63%), red seabream (62%), haddock (62%), carp (62%), and zebrafish (61%). The phylogenetic tree showed that C. reevesii VTG existed between the amphibian and birds, and it was present far from fish VTGs. A reverse transcription-polymerase chain reaction method was employed to detect the mRNA expression of the C. reevesii VTG through the use of primers designed from our sequence. The VTG mRNA expression (292 bp) was proven in the total RNA extraction from the liver of the juvenile turtles which were treated with estradiol-17β. The information herein would be useful for ecotoxicological studies using freshwater turtles and these findings are expected to contribute positively towards wildlife conservation.
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  • Akihito CHUGUN, Tsuyoshi UCHIDE, Chieko TSURIMAKI, Hajime NAGASAWA, Ta ...
    Article type: FULL PAPER
    2008 Volume 70 Issue 3 Pages 255-264
    Published: 2008
    Released on J-STAGE: April 04, 2008
    JOURNAL FREE ACCESS
    We reported previously that doxorubicin, an anticancer agent that has an anthracycline structure, alters Ca2+ releasing and uptake mechanisms in the sarcoplasmic reticulum of myocardial cells. These effects of doxorubicin are apparently related to its cardiotoxicity. Mitoxantrone is a similar anticancer agent with an anthracenedion structure that has been shown to be significantly less cardiotoxic. In the present study, the effects of mitoxantrone on the functions of the sarcoplasmic reticulum were examined in isolated muscle preparations obtained from the guinea-pig heart. In electrically-stimulated left atrial muscle preparations, incubation in vitro for 4 hr with 30 or 100 μM mitoxantrone significantly prolonged the time to the peak of twitch tension, markedly increased the developed tension observed at lower stimulation frequencies, thereby attenuating the slope of positive force-frequency relationships, and increased the postrest contraction observed after a 60-sec quiescent period. In myocytes isolated from ventricular muscles, 30 μM mitoxantrone increased the peak and the size of intracellular Ca2+ concentrations ([Ca2+] i), and prolonged the time to peak [Ca2+]i. In skinned muscle fiber preparations obtained from the left ventricular muscle, 30 μM mitoxantrone significantly increased the caffeine-induced contraction without affecting the Ca2+ sensitivity of contractile proteins. These results suggest that mitoxantrone enhances Ca2+ release from the sarcoplasmic reticulum in isolated atrial muscle preparations obtained from the guinea-pig heart. Apparent enhancement of the sarcoplasmic reticulum functions, in contrast to anthracyclines that has been shown to suppress these functions, seems to explain the relative lack of marked cardiotoxicity of mitoxantrone.
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