Studying the gravity-dependent characteristics of regolith, fine-grained granular media covering extra-terrestrial bodies is essential for the reliable design and analysis of landers and rovers for ...space exploration. In this study, we propose an experimental approach to examine a granular flow under stable artificial gravity conditions for a long duration generated by a centrifuge at the International Space Station. We also perform a discrete element simulation of the granular flow in both artificial and natural gravity environments. The simulation results verify that the granular flows in artificial and natural gravity are consistent. Further, regression analysis of the experimental results reveals that the mass flow rate of granular flow quantitatively follows a well-known physics-based law with some deviations under low-gravity conditions, implying that the bulk density of the granular media decreases with gravity. This insight also indicates that the bulk density considered in simulation studies of space probes under low-gravity conditions needs to be tuned for their reliable design and analysis.
Abstract Fetal fibroblast cell culture from cotyledons of bovine placenta and animal experiments close to term were used to elucidate afterbirth release and factors missing in the signal transduction ...mechanism for retained fetal membranes (RFM) after delivery. In cell culture the addition of arachidonic acid (Ara) to the medium caused rapid release to free floating cell in the culture dish, accompanied by matrix metalloproteinase (MMP) activation, being consistent with previous in vivo observations, where a relation between MMP and fetal membrane release had been shown. Ara-induced cell floating was not inhibited by the addition of cyclooxygenase (COX) inhibitor, and not induced by the addition of PGF2α or PGE2 to replace Ara, while 12-lipoxygenase (12-LOX) metabolite of Ara, 12-oxo-eicosatetraenoic acid (12-oxoETE), strongly induced cell floating. In the animal experiments, 12-oxoETE injection to delivery-induced cows ( n = 6) using prostaglandin (PG) and dexamethazone resulted in rapid release of fetal membranes. In cows with natural calf delivery, a 12-oxoETE peak (11.7–16.8 ng/ml) was observed in maternal blood plasma prior to release of fetal membranes. This investigation thus gives new indications for that the mediator for fetal membrane release is 12-oxoETE and not PG.
The aims of the present study were to determine whether salsolinol (SAL), a dopamine-related compound, is present in the bovine posterior pituitary (PP) gland, and to clarify the effect of SAL on the ...secretion of prolactin (PRL) in ruminants. SAL was detected in extract of bovine PP gland using high-pressure liquid chromatography with electrochemical detection (HPLC-EC). A single intravenous (i.v.) injection of SAL (5 and 10
mg/kg body weight) significantly and dose-dependently stimulated the release of PRL in goats (
P
<
0.05). Plasma PRL levels reached a peak 10
min after the injection, then gradually returned to basal values in 60–80
min. The PRL-releasing pattern was similar to that in response to sulpiride (a dopamine receptor antagonist). The intracerebroventricular (i.c.v.) injection of 1
mg of SAL had no significant effect on the release of PRL in calves, however, 5
mg significantly stimulated the release (
P
<
0.05) with peak values reached 30–40
min after the injection. Moreover, SAL significantly stimulated the release of PRL from cultured bovine anterior pituitary cells at doses of 10
−6 and 10
−5
M, compared to control cells (
P
<
0.05). Taken together, our data clearly show that SAL is present in extract of the PP gland of ruminants, and has PRL-releasing activity both in vivo and in vitro. Therefore, this endogenous compound is a strong candidate for the factor having PRL-releasing activity that has been previously detected in extract of the bovine PP gland.
To understand the regulatory mechanism of the secretory rhythm of GH and the involvement of melatonin (MEL) in GH regulation in cattle, daytime and nighttime profiles of GH secretion and the effect ...of a photic stimulation on nocturnal GH and MEL secretion were investigated in Holstein steers. Steers were kept under a constant lighting condition of 12 h of light (LIGHT; 500 lx, 0600 to 1800 h):12 h of dark (DARK; 10 lx, 1800 to 0600 h). In Exp. 1, blood was taken for 4 h at 15-min intervals during LIGHT (1100 to 1500 h) and DARK (2300 to 0300 h), respectively. The sampling was also performed from 0500 to 0900 h, with the usual light transition (light onset at 0600 h; morning sampling). In Exp. 2, steers were exposed to light (500 lx) for 1 h from 0000 to 0100 h. Plasma GH and MEL concentrations were determined by RIA and enzyme immunoassay, respectively. Both GH (P < 0.05) and MEL (P < 0.01) concentrations in plasma for 4 h during DARK were greater than those during LIGHT. On the other hand, although MEL concentrations were decreased after the light onset at 0600 during the morning, GH release was not altered. Increased GH secretion during DARK was suppressed (P < 0.01) by the 1 h of light exposure, as were MEL concentrations (P < 0.05). Pineal MEL, which was affected by the photic condition, may play an important role in the secretory rhythm of GH secretion in cattle.
Abstract Although neuromedin U (NMU) and neuromedin S (NMS) are reported to modulate stress responses mainly through corticotropin-releasing hormone system in rodents, the in vivo effects of ...centrally administered NMU or NMS on stress regulation have not been fully elucidated in cattle. We examined adrenocorticotropic hormone levels, body temperature, and behavioral responses to intracerebroventricularly (ICV) administered rat NMU or rat NMS in steers. ICV NMU and NMS (0.2, 2, and 20 nmol/200 μl) evoked a dose-related increase in plasma cortisol concentrations (CORT). There was a significant time–treatment interaction for the time course of CORT ( p < 0.001). ICV NMU evoked a dose-related increase in rectal temperature (RT). There was a significant time–treatment interaction for the change in RT from pre-injection value ( p < 0.05). There was a significant difference among treatments in the percentage of time spent lying (Friedman’s test, χ2 = 15.6, p < 0.01) and in the total number of head shaking (Friedman’s test, χ2 = 14.49, p < 0.01). A high dose of NMS tended to shorten the duration of lying and increase the number of head shaking. These findings indicate that both central NMU and NMS might participate in controlling the hypothalamo–pituitary–adrenal axis, that central NMU might participate in controlling body temperature, and that central NMS is likely to be involved in behavioral activation in cattle.
Division of Cardiovascular Surgery, Hiroshima-city Asa General Hospital, 2-1-1, Kabe-minami, Asa-Kita-Ku, Hiroshima 731-0293, Japan
*Corresponding author. Tel.: +81-82-815-5211; fax: +81-82-814-1791. ...E-mail address : uchidacvs{at}yahoo.co.jp (N. Uchida).
This study is retrospectively to evaluate strategies for organ malperfusion on the view point of two mechanisms (true lumen collapse in the aorta=Ao type, or branch dissection=Br type) in acute type B aortic dissection. There were 16 of Ao type and 4 of Br type in 20 patients with organ malperfusion. In Ao type, we performed entry closure in 12 patients, surgical bypass grafting in two to superior mesenteric artery (SMA) in one and femoral artery in two, and surgical fenestration in two. In Br type, we performed interventional non-covered stenting to the orifice of visceral arteries in two patients, surgical bypass to SMA with ileum resection in one, and surgical bypass to SAM and renal arteries in one. Five patients in 16 of Ao type died within 30 days that had two multiple organ failure after entry closure, one aortic injury during endovascular stent graft repair, two more multiple organ failure after femoral bypass, however, all four patients in Br type were rescued. Central aortic operation to true lumen collapse with entry closure for Ao type ischemia and organ reperfusion with extra-anatomical bypass or non-covered stent to ischemic arteries for Br type ischemia should be performed before catastrophic status.
Key Words: Acute aortic dissection; Organ malperfusion; Surgical strategies
To understand the regulatory mechanism of the secretory rhythm of GB and the involvement of melatonin (MEL) in GH regulation in cattle, daytime and nighttime profiles of GH secretion and the effect ...of a photic stimulation on nocturnal GH and MEL secretion were investigated in Holstein steers. Steers were kept under a constant lighting condition of 12 h of light (LIGHT; 500 lx, 0600 to 1800 h):12 h of dark (DARK; 10 lx, 1800 to 0600 h). In Exp. 1, blood was taken for 4 h at 15-mm intervals during LIGHT (1100 to 1500 h) and DARK (2300 to 0300 h), respectively. The sampling was also performed from 0500 to 0900 h, with the usual light transition (light onset at 0600 h; morning sampling). In Exp. 2, steers were exposed to light (500 lx) for 1 h from 0000 to 0100 h. Plasma GH and MEL concentrations were determined by RIA and enzyme immunoassay, respectively. Both GH (P <0.05) and MEL (P < 0.01) concentrations in plasma for 4 h during DARK were greater than those during LIGHT. On the other hand, although MEL concentrations were decreased after the light onset at 0600 during the morning, GH release was not altered. Increased GH secretion during DARK was suppressed (P < 0.01) by the 1 h of light exposure, as were MEL concentrations (P < 0.05). Pineal MEL, which was affected by the photic condition, may play an important role in the secretory rhythm of GH secretion in cattle. PUBLICATION ABSTRACT
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