Consulta: creatorFacets:"ACOSTA, Tomas J."
Registros recuperados: 8
Data/hora: 01/06/2024 06:21:35

Relationship between Peripartal Plasma Oxytocin and Prostaglandin F2α Metabolite and Placental Expulsion Time in Heavy Draft Mares
Provedor de dados: Obihiro University of Agriculture and Veterinary Medicine Academic Repository (OAK)
Autores: ISHII, Mitsuo; KOBAYASHI, Syuichi; ACOSTA, Tomas J.; MIKI, Wataru; YAMANOI, Takahiro; MATSUI, Motozumi; MIYAKE, Yoh-Ichi; MIYAMOTO, Akio; 石井, 三都夫; 松井, 基純; 三宅, 陽一; 宮本, 明夫.
The aim of this study was to clarify the relationship between circulating oxytocin (OT) and PGF2α metabolite (PGFM) in mares at the third stage of labor and placental expulsion time in order to investigate a cause of retained placenta of which the incidence increase in a heavy draft mare. Blood was sampled every 5 min from foaling to expulsion of the placenta in 18 heavy draft mares to evaluate circulating OT and PGFM. The relationships between OT and PGFM concentration and recorded placental expulsion times were investigated. The results were as follows (1) The highest level of OT concentration was observed close to foaling in 15 mares. (2) The OT concentrations close to foaling were variable with a large difference from the lowest concentration, 22.1...
Palavras-chave: Heavy draft mare; Oxytocin; 15-keto-dihydro prostaglandin F2α (PGFM); Placental expulsion.
Ano: 2008
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/3089

In Vivo Evidence that Local Cortisol Production Increases in the Preovulatory Follicle of the Cow
Provedor de dados: Obihiro University of Agriculture and Veterinary Medicine Academic Repository (OAK)
Autores: ACOSTA, Tomas J.; TETSUKA, Masa; MATSUI, Motozumi; SHIMIZU, Takashi; BERISHA, Bajram; SCHAMS, Dieter; MIYAMOTO, Akio; 松井, 基純; 清水, 隆; 宮本, 明夫.
The aim of the present in vivo study was to monitor real-time fluctuations of cortisol (Cr) in the wall of preovulatory follicles using a microdialysis system (MDS) implanted in the theca layer as well as changes in ovarian venous plasma (OVP) and jugular venous plasma (JVP). Seven cows were superovulated using FSH and prostaglandin F2α injections. Dialysis capillary membranes were surgically implanted into the theca layer of mature follicles and connected to a microdialysis system. Fractions of the perfusates were collected from Day -1 (Day 0=LH surge) to Day 3. No difference in the concentrations of Cr between JVP and OVP was detected throughout the experiment. Circulating concentrations of Cr ranged from 20 to 35 ng/ml 8 h after surgery in ovulatory and...
Palavras-chave: Bovine; Cortisol; Follicle; Ovary; Ovulation.
Ano: 2005
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2980

Intraluteal Release of Prostaglandin F2α and E2 During Corpora Lutea Development in the Cow
Provedor de dados: Obihiro University of Agriculture and Veterinary Medicine Academic Repository (OAK)
Autores: KOBAYASHI, Shu-ichi; ACOSTA, Tomas J.; HAYASHI, Kanako; BERISHA, Bajram; OZAWA, Takahiro; OHTANI, Masayuki; SCHAMS, Dieter; MIYAMOTO, Akio; 宮本, 明夫.
It is well known that prostaglandin (PG) F2α and PGE2 are actively produced by bovine early corpus luteum (CL) at higher levels than in the CL of later stages. However, there is no in vivo information about the local secretion of PGs within bovine developing CL so far. Thus, the objective of the present study was to determine in detail the real-time changes in PGF2α and PGE2 secretion within developing CL. A microdialysis system (MDS) was surgically implanted into the newly formed CL of 6 cows on Day 3 after GnRH administration (about 1.5 days after ovulation) to induce superovulation following FSH treatment. Both PGF2α and PGE2 release were high during the first 24 h within developing CL but decreased thereafter. These profiles were well reflected in the...
Palavras-chave: PGF2α; PGE2; Developing CL; Cow; In vivo.
Ano: 2002
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2974

Relative Changes in mRNA Expression of Angiopoietins and Receptors Tie in Bovine Corpus Luteum during Estrous Cycle and Prostaglandin F2α-induced Luteolysis: A Possible Mechanism for the Initiation of Luteal Regression
Provedor de dados: Obihiro University of Agriculture and Veterinary Medicine Academic Repository (OAK)
Autores: TANAKA, Jun; ACOSTA, Tomas J.; BERISHA, Bajram; TETSUKA, Masa; MATSUI, Motozumi; KOBAYASHI, Shuichi; SCHAMS, Dieter; MIYAMOTO, Akio; 松井, 基純; 宮本, 明夫.
Local angiogenesis and angiolysis in the corpus luteum (CL) relate to the luteal function. Recent studies indicate that angiopoietins (ANPT) and their receptors Tie regulate remodeling of microvasculature. We therefore examined 1) the relative changes in the expression of mRNA for ANPT-1, ANPT-2, Tie1 and Tie2 in bovine CL by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) during the estrous cycle and prostaglandin F2α (PGF2α)-induced luteolysis, and 2) the effect of ANPT-2 on progesterone (P4) release from CL at the late stage of the estrous cycle by an in vitro microdialysis system (MDS). The CLs were classified into 4 stages (early: Day 2-5, n=7, mid: Day 8-12, n=15, late: Day 15-17, n=9, regressing: Day &gt;18, n=19). The...
Palavras-chave: Angiopoietin; Angiolysis; Luteolysis; Corpus luteum; Cow.
Ano: 2004
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2977

A Potential Use of Color Ultrasound as a Tool for Reproductive Management: New Observations Using Color Ultrasound Scanning that were not Possible with Imaging Only in Black and White
Provedor de dados: Obihiro University of Agriculture and Veterinary Medicine Academic Repository (OAK)
Autores: MIYAMOTO, Akio; SHIRASUNA, Koumei; HAYASHI, Ken-Go; KAMADA, Daichi; KAWASHIMA, Chiho; KANEKO, Etsushi; ACOSTA, Tomas J.; MATSUI, Motozumi; 宮本, 明夫; 白砂, 孔明; 川島, 千帆; 松井, 基純.
Ultrasonography (US) has been applied to the ovary and the uterus of domestic animals from the late 1980s, and established in 1990s as a practical tool for animal production. US made it possible to detect pregnancy at a very early stage and, most importantly, to observe the real-time dynamics of follicular development and hence the discovery of follicular waves. This has greatly contributed to our understanding of ovarian physiology and helped us to develop several "pin-point" protocols for hormonal treatment. While US may not seem to fit preconceived ideas of a "green" technology, it does not contravene environmental priorities, and it is non-invasive ("ethical") and non-hormonal ("clean"). Using the US technology that is now commercially available at a...
Palavras-chave: Color Doppler ultrasound; Blood flow; Ovary; Reproduction; Cow.
Ano: 2006
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2983

Changes of Progesterone and Endothelin Concentrations in the Peripheral Plasma of Female Calves and Cycling Cows: Effects of PGF2α Injection
Provedor de dados: Obihiro University of Agriculture and Veterinary Medicine Academic Repository (OAK)
Autores: OHTANI, Masayuki; OKI, Naoko; TANIMURA, Miyune; KOBAYASHI, Shu-ichi; ACOSTA, Tomas J.; HAYASHI, Kanako; MIYAMOTO, Akio; 宮本, 明夫.
It is well known that an injection of prostaglandin F2α (PGF2α) or its analogue during the mid luteal phase of the estrous cycle induces a rapid decrease in plasma progesterone (P4) concentration, followed by luteolysis in the cow. There is evidence that a potent vasoactive peptide, endothelin-1 (ET-1), is produced in the bovine corpus luteum (CL), and that it is directly involved in luteolysis. We previously found that ET-1 concentrations in the peripheral plasma increase during the period of luteolysis and ovulation in cows. However, it is not clear whether the elevation of peripheral plasma ET-1 concentration observed during luteolysis and ovulation originates exclusively from the ovary and/or CL. Such a profile of plasma ET-1 concentration may be...
Palavras-chave: Endothelin; Progesterone; Plasma; Calves; Cows.
Ano: 2001
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2973

Effect of the Dominant Follicle Aspiration before or after Luteinizing Hormone Surge on the Corpus Luteum Formation in the Cow
Provedor de dados: Obihiro University of Agriculture and Veterinary Medicine Academic Repository (OAK)
Autores: HAYASHI, Ken-Go; MATSUI, Motozumi; ACOSTA, Tomas J.; KIDA, Katsuya; MIYAMOTO, Akio; 松井, 基純; 木田, 克弥; 宮本, 明夫.
Luteinizing hormone (LH) surge and follicle rupture act as trigger to start corpus luteum (CL) formation. Thus, we aimed to investigate whether a dominant follicle that has not been exposed to an LH surge can become a functional CL. For this purpose, follicular fluid from the dominant follicles (DF) of cows was aspirated before or after a GnRH-induced LH surge, and subsequent CL formation was observed. Holstein cows were divided into four groups as follows: Luteal phase, a DF was aspirated 7 days after GnRH injection; Pre-LH surge, a DF was aspirated 42 h after PGF2α injection during the mid luteal phase; Post-LH surge, a DF was aspirated 24 h after GnRH injection following PGF2α; and Intact follicle, ovulation was induced by GnRH injection after PGF2α....
Palavras-chave: Corpus luteum formation; Cow; Follicle aspiration; LH surge.
Ano: 2006
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2982

Changes in Follicular Vascularity during the First Follicular Wave in Lactating Cows
Provedor de dados: Obihiro University of Agriculture and Veterinary Medicine Academic Repository (OAK)
Autores: ACOSTA, Tomas J.; HAYASHI, Ken-Go; MATSUI, Motozumi; MIYAMOTO, Akio; 松井, 基純; 宮本, 明夫.
Increase in the blood supply to individual follicles appears to be associated with follicular growth rates and the ability to become the dominant follicle, while reduced thecal vascularity appears to be closely associated with follicular atresia. Therefore, this study aimed to determine the real-time changes in the vascularity of the follicle wall during the first follicular wave in cycling Holstein cows. Normally cycling and lactating cows (n=5) were examined by transrectal color Doppler ultrasonography (the sensitivity for velocity: &gt; 2 mm/sec) to determine the changes in the vasculature of the follicle wall (presence or absence of blood flow) and the diameter of follicles. A new follicular wave and ovulation were induced by GnRH injection at 48 h...
Palavras-chave: Blood flow; Follicular wave; Selection; Deviation; Cow.
Ano: 2005
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2979