Kazuro Miyahara

Obihiro University of Agriculture and Veterinary Medicine, Obibiro, Hokkaidō, Japan

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Publications (12)20.42 Total impact

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    ABSTRACT: To clarify the different characteristics of the dominant follicle (DF), the DF in first ovarian follicular wave (DF-1) after spontaneous ovulation and DF in second follicular wave (DF-2) and after induced ovulation of the first-wave DF by GnRH were examined in non-lactating Holstein cows. Follicular maturation of DF-1 and DF-2 were induced by PGF2α and GnRH treatment on Day 6 and 8 (Day 0 = Day of follicular wave emergence), respectively. Follicular growth and blood flow (BF) in the follicular wall of DF-1 and DF-2 were examined. To analyze sex steroids in follicular fluid (FF) and amount of mRNA in granulosa cells, DF-1 and DF-2 were aspirated on Day 8 or 9 in different estrous cycle. Diameter in DF-1 was larger than DF-2 on Day 8 and 9. From Day 8 to 9, BF area (BFA) and percentage of the follicular wall with BF, which represents the degree of distribution of BF, increased in DF-1 but not in DF-2. BFA per length of follicle circumference with BF, which represents the thickness of BF, was not different between DF-1 and DF-2. Concentrations of 17β-estradiol (E2) in plasma, E2 and androstendione in FF and amounts of LH receptor mRNA were greater in the DF-1 on Day 8. Gene expression for steroidogenesis, prostaglandin synthesis and angiogenesis did not differ between DF-1 and DF-2. These results indicated that DF-1 were more active than DF-2 in growth, BF supply and steroidogenesis. The greater BFA observed in the DF-1 may be derived from as a result of the greater vascularity in the follicular wall.
    Animal reproduction science 03/2014; · 1.56 Impact Factor
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    ABSTRACT: A nine-month-old steer was autopsied due to recurrent ruminal tympany. A macroscopic examination found an enlarged caudal mediastinal lymph node, and the section of the lymph node presented as necrosis with marked calcification, similar to tuberculous lymphadenitis. Histopathologically the lesion consisted of multiple coagulative necrotic foci and fibrosis with macrophage, lymphocyte, eosinophil and multinucleated giant cell infiltration. Non-uniform width hyphae were detected in the necrotic area and within the cytoplasm of the multinucleated giant cells, and they were found to be anti-Rhizopus arrhizus antibody positive in an immunohistochemical examination. Therefore, the steer was diagnosed with necrotic caudal mediastinal lymphadenitis due to zygomycetes infection, and inhibition of eructation by the enlarged lymph node was the likely cause of the ruminal tympany.
    Journal of Veterinary Medical Science 09/2013; · 0.88 Impact Factor
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    ABSTRACT: To obtain B-mode ultrasound images of mammary glands in dairy heifers at different stages of growth, 25 clinically normal Holstein heifers were used. The heifers were divided into 5 groups (n=5/group) by stage of their growth: 2-month-old (group 1), 5-month-old (group 2), postpuberty (group 3), mid (group 4), and late (group 5) pregnancy. Furthermore, the sections of mammary glands were observed grossly at postmortem examination in one heifer in each group. Ultrasound images varied with the development of mammary glands. In group 1, the mammary glands had distinctive ultrasonographic findings: an oval to fusiform homogeneous hypoechoic structure. In all groups except group 1, mammary tissue consists of two major areas: a homogeneous, medium echogenic area and a poorly-defined, heterogeneous, hypoechoic area mostly in the superficial part. The superficial hypoechoic area spread more extensively and more irregularly with the development of mammary glands. Most pregnant heifers had irregular and extremely hypoechoic or anechoic areas like lactiferous sinus in the glands. The gross findings of mammary glands suggested that the hypoechoic areas of various shapes represented the lactiferous sinus and ducts. Thus, these results indicate that B-mode ultrasound imaging can visualize the internal structures of udders and could be a useful tool for evaluation of mammary glands in heifers.
    Journal of Veterinary Medical Science 01/2011; 73(1):19-24. · 0.88 Impact Factor
  • Biology of Reproduction 10/2010; · 4.03 Impact Factor
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    ABSTRACT: The assisted reproductive techniques (ARTs) such as in vitro fertilization, embryo transfer, and cryopreservation of gametes have contributed considerably to the development of biomedical sciences in addition to improving infertility treatments in humans as well as the breeding of domestic animals. However, ARTs used in canine species have strictly limited utility when compared with other mammalian species, including humans. Although successful somatic cell cloning has been reported, artificial insemination by frozen semen to date is only available for the improved breeding and reproduction for companion and working dogs as well as guide dogs for the blind. We describe here the successful cryopreservation of embryos and subsequent embryo transfer in dogs. Canine embryos were collected from excised reproductive organs after artificial insemination and subsequently cryopreserved by a vitrification method. When the 4-cell to morula stage of cryopreserved embryos were nonsurgically transferred into the uteri of nine recipient bitches using a cystoscope, five recipients became pregnant and four of them delivered a total of seven pups. The cryopreservation of embryos in canine species will facilitate the transportation and storage of genetic materials and will aid in the elimination of vertically transmitted diseases in dogs. In addition, this technique will contribute to the improved breeding of companion and working dogs such as guide dogs, drug-detecting dogs, and quarantine dogs.
    Biology of Reproduction 10/2010; 84(2):363-8. · 4.03 Impact Factor
  • Veterinary Radiology &amp Ultrasound 01/2009; 50(3):301-3. · 1.41 Impact Factor
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    ABSTRACT: DNA from 111 ticks collected by flagging in Tokachi district, Eastern Hokkaido, Japan were examined for infection with Rickettsia and Ehrlichia, by PCR and sequencing methodology. For Rickettsia, analysis of the partial sequence of the citrate synthase gene was successfully performed on 11 DNA samples from I. persulcatus, and 7 of them showed 99.8% identical with Rickettsia helvetica while the other 4 showed 99.8% identical with ;Candidatus Rickettsia tarasevichiae'. For Ehrlichia, a partial sequence of the 16S rRNA gene detected from I. persulcatus was 100% identical with that from Ehrlichia muris, and another DNA sample from I. ovatus showed 99.8% identical with Ehrlichia species detected from I. ovatus. The results suggest that the pathogens detected here might be distributed in this area.
    Journal of Veterinary Medical Science 07/2007; 69(6):661-4. · 0.88 Impact Factor
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    ABSTRACT: Brucella canis is the causative agent of canine brucellosis and facultative intracellular pathogen. The diagnosis of canine brucellosis is based on bacteriological examination and serological methods including agglutination and gel diffusion tests. In this study, crude antigens were extracted from B. canis using hot saline, coated on to latex beads and their usefulness in the serological diagnosis of canine brucellosis was examined. Mixing the antigen coated latex beads with the sera of dogs infected with B. canis produced clear agglutination, but this was not so for B. canis free dog sera. N-terminal amino acid sequence analysis of the crude hot saline extracts, showed that they contained copper-zinc superoxide dismutase, ribose ABC transporter and hypothetical protein of Brucella as antigens. A serological survey of canine serum samples conducted by means of an agglutination test using the antigen coated latex beads, showed that this method was more specific than the tube agglutination test using whole bacterial cell antigens. Although these results suggest that our method in which crude hot saline extracted antigens are coated on to latex beads would be useful in the serological diagnosis of canine brucellosis, we need further investigation using more serum samples to confirm the usefulness of our method.
    Journal of Veterinary Medical Science 06/2007; 69(5):477-80. · 0.88 Impact Factor
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    ABSTRACT: Tick DNA samples from cattle in Xinjiang Uygur Autonomous Region Area, China, were examined for Rickettsia infection by citrate synthase gene-based PCR and sequencing. Four positive samples were detected from Haemaphysalis danieli and high levels of similarity were found with recently detected 'Candidatus Rickettsia principis.'
    Veterinary Parasitology 04/2007; 144(1-2):184-7. · 2.38 Impact Factor
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    ABSTRACT: To quantify the radiographic parameters of the caudal vena cava (CVC) in healthy cattle and demonstrate their clinical usefulness, the present study compared the ratios of the diameter of the thoracic CVC to the diameter of the aorta (Ao) and length of the thoracic vertebrae (VL), which are all positioned in the same intercostal space, in 81 healthy control cattle (43 growing, 38 adult) and 10 cattle with heart disease. The average diameter of the CVC (CVCave) was correlated with the size of the Ao and VL in the control cows. Although the diameter and pulsation index of the CVC differed significantly between the growing and adult cows, the ratios of CVC/Ao and CVC/VL were fixed values for both the growing and mature cattle. However, in the cattle with heart disease, the pulsation index of the CVC was significantly lower or there was absence of pulsation due to a dilated CVC, and the ratio of CVCave/Ao and CVCave/VL were significantly higher than those in the healthy cattle.
    Journal of Veterinary Medical Science 10/2006; 68(9):995-8. · 0.88 Impact Factor
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    ABSTRACT: The cryopreservation of ovarian tissues is a technology with significant potential for the preservation of the genetic resource materials of working dogs, including guide dogs for the blind. However, no attempt has been reported on cryopreservation of the canine ovary. Thus, we evaluated a vitrification method for cryopreservation of canine ovaries and determined the potential functionality of vitrified-warmed canine ovaries by means of transplantation into non-obese diabetic-severe combined immunodeficiency (NOD-SCID) mice. All ovarian tissues cryopreserved by vitrification were morphologically normal in terms of histology. Cryopreserved ovaries were transplanted into the ovarian bursa of the NOD-SCID mice, and the xenografts were recovered from 23 of 23 mice (100%) 4 weeks after the operation. The transplanted canine tissue was tightly adhered to the mouse ovary. Although antral follicle formation did not occur after grafting, proliferating cell nuclear antigen immunoreactivity was detectable in many of the granulosa cells in the primary follicles of the grafts. These results indicate that cryopreservation of the canine ovary by vitrification appears to have the potential to restore endocrine function and ovulation potential.
    Journal of Reproduction and Development 05/2006; 52(2):293-9. · 1.76 Impact Factor
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    ABSTRACT: A high prevalence of larval Echinococcus multilocularis (Em) infection was found in zoo primates in Hokkaido, Japan. In October 1997, a Japanese monkey (Macaca fuscata) died and histopathologically diagnosed as alveolar hydatidosis. Serum samples were collected from the remaining Japanese monkeys and examined for antibodies against Em by enzyme-linked immunosorbent assay and western blotting. Serological tests showed 12 more animals of the remaining 57 monkeys were possibly infected. Ultrasonography revealed that nine of these 12 animals had a cystic lesion in the liver. The band patterns of western blotting in the monkeys were very similar to those in human.
    Journal of Veterinary Medical Science 02/2005; 67(1):133-5. · 0.88 Impact Factor

Publication Stats

71 Citations
20.42 Total Impact Points


  • 2006–2014
    • Obihiro University of Agriculture and Veterinary Medicine
      • • Department of Clinical Veterinary Science
      • • School of Veterinary Medicine
      Obibiro, Hokkaidō, Japan
  • 2011
    • Gifu University
      • United Graduate School of Veterinary Sciences
      Gihu, Gifu, Japan