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1.
J Reprod Dev ; 66(5): 453-458, 2020 Oct 13.
Article de Anglais | MEDLINE | ID: mdl-32595196

RÉSUMÉ

This study aimed to determine if lactation can be induced by exogenous hormonal treatment in non-pregnant sows. In experiment 1, pseudopregnant animals were divided into four groups and given: 1) 5 mg of estradiol dipropionate (EDP) 5 days before (n = 4), 2) 5 mg of EDP 10 days before (n = 3), 3) 10 mg of EDP 5 days before (n = 3) or 4) 10 mg of EDP 10 days (n = 3) before PGF2α treatment. Artificial lactation was induced in seven pseudopregnant sows (53.8%) by exogenous hormonal treatment. There was no significant effect of either an increased EDP dosage or interval from the EDP treatment to PGF2α treatment on the induction rate of artificial lactation. In experiment 2, milk samples were collected from artificial lactating and natural lactating sows (n = 6). IgG and IgA levels in the milk collected from both groups were significantly associated with time during the experimental period. Milk IgG levels 24 h after PGF2α treatment in artificial lactating sows were higher than those in the colostrum of lactating sows. In experiment 3, hormonal profiles in pseudopregnant sows with (n = 3) or without (n = 3) EDP treatment were determined. There was a significant difference in estradiol-17ß levels on days 8, 7 and 5 before PGF2α treatment between groups. Progesterone and prolactin concentrations did not differ between groups. The present study revealed for the first time that lactation could be induced by exogenous hormonal treatment in non-pregnant sows and that the milk collected from these sows contained high immunoglobulin levels.


Sujet(s)
Oestradiol/analogues et dérivés , Oestradiol/métabolisme , Oestrus/effets des médicaments et des substances chimiques , Hormones/métabolisme , Immunoglobuline A/immunologie , Immunoglobuline G/immunologie , Lactation , Animaux , Colostrum/métabolisme , Oestradiol/pharmacologie , Synchronisation de l'oestrus , Femelle , Lait , Progestérone/pharmacologie , Grossesse nerveuse/induit chimiquement , Suidae
2.
J Vet Med Sci ; 82(5): 590-597, 2020 May 15.
Article de Anglais | MEDLINE | ID: mdl-32173693

RÉSUMÉ

The factors that affect the interval to ovulation, the type of ovulated dominant follicle (DF), and the cause of anovulation after prostaglandin (PG) treatment were investigated. Nine cows were assigned to six groups (54 cows in total) but the group size was later fixed at eight cows (48 in total). They received 25 mg tromethamine dinoprost as dinoprost on Day 6 (Group D6), Day 7 (Group D7), Day 8 (Group D8), Day 9 (Group D9), Day 10 (Group D10), or Day 11 (Group D11) after natural ovulation (Day 0). If the DF did not ovulate, then the cow was assigned to Group NO. In Group D6, the 1st DF ovulated in all cows 4 days after PG treatment, whereas in Groups D9, D10, and D11, the 2nd DF ovulated in all cows 4 to 7 days after PG treatment. In 10 cows, the DF did not ovulate, and late anovulation was significantly higher in Group D6 cows than in Group D11 cows. The progesterone (P4) levels decreased to less than 1 ng/ml in all groups on the day after PG treatment. The estradiol-17ß (E2) levels began to increase after PG treatment and peaked at 2 days before ovulation in the cows that ovulated. In anovulated cows, E2 tended to be higher and there was no clear E2 peak in some cows. These results indicated that the number of days to ovulation, the type of ovulated DF, and anovulation were affected by factors that were associated with the DF when it was producing E2.


Sujet(s)
Bovins/physiologie , Dinoprost/analogues et dérivés , Follicule ovarique/effets des médicaments et des substances chimiques , Ovulation/effets des médicaments et des substances chimiques , Animaux , Dinoprost/administration et posologie , Dinoprost/pharmacologie , Oestradiol/sang , Femelle , Follicule ovarique/métabolisme , Progestérone/sang
3.
J Vet Med Sci ; 81(5): 703-706, 2019 May 11.
Article de Anglais | MEDLINE | ID: mdl-30944273

RÉSUMÉ

We describe the successful surgical repair of third-degree perineal lacerations with rectovestibular fistulae in four cases using the single-stage modified Aanes method with purse-string suture of the vaginal vestibule and rectum. Fistulae formation and dehiscence of the repair were not observed after surgery. Two cows had five calves and one cow had four calves after surgery. The pregnant cows delivered normally. Additionally, there was no dehiscence of the suture line during the subsequent parturition. The breeding and fertility results obtained after the surgery are presented. According to the results of the present study, the modified Aanes method for the repair of third-degree perineal lacerations with rectovestibular fistulae appears to have a good prognosis for fertility following surgery in cows.


Sujet(s)
Maladies des bovins/chirurgie , Complications du travail obstétrical/médecine vétérinaire , Périnée/traumatismes , Fistule rectovaginale/médecine vétérinaire , Animaux , Bovins , Femelle , Fécondité , Complications du travail obstétrical/chirurgie , Périnée/chirurgie , Grossesse , Fistule rectovaginale/chirurgie
4.
Biochem J ; 474(20): 3499-3512, 2017 10 10.
Article de Anglais | MEDLINE | ID: mdl-28899944

RÉSUMÉ

Endogenous retroviruses (ERVs) are involved in placentation; perhaps, the most well-known ERVs are the syncytins, actively transcribed env genes involved in cell-cell fusion and possible morphological variations. However, ERVs other than syncytins that play an important role in placental development have not been well characterized. To identify ERV genes expressed during the onset of placentation in the bovine species, we characterized the expression profiles of bovine conceptus transcripts during the peri-attachment period using RNA-seq analysis, and confirming some candidates through real-time PCR. Using in silico and PCR analyses, we identified a novel ERV proviral sequence derived from a gag region, designated bovine endogenous retroviruses (BERV)-K3, containing Gag_p10 and Gag_p24, zinc finger domain. Initial expression of this ERV in bovine conceptuses was on day 20 (day 0 = day of estrus), soon after conceptus attachment to the endometrial epithelium, and its high placental expression was maintained up to the middle of pregnancy. The BERV-K3 transcript was also found in the uterine luminal and glandular epithelia, liver, kidney, intestine, and skin. BERV-K3 is located on chromosome 7 and integrated within LOC100848658, from which noncoding RNA could be transcribed. Furthermore, the expression of endogenous BERV-K3 in bovine trophoblast cell lines was induced by a WNT agonist, a signaling system common to genes expressed in placentas. These data support the argument that during the evolutionary process, mammals incorporated not only similar ERV sequences, but also ERVs unique to individual species. BERV-K3 is in the latter case, likely providing functions unique to ruminant gestation.


Sujet(s)
Rétrovirus endogènes/génétique , Régulation de l'expression des gènes au cours du développement , Placenta/physiologie , Transcription génétique/physiologie , Voie de signalisation Wnt/physiologie , Animaux , Bovins , Femelle , Grossesse
5.
Theriogenology ; 81(3): 454-8, 2014 Feb.
Article de Anglais | MEDLINE | ID: mdl-24286690

RÉSUMÉ

To study the ovarian response to the long-term effect of PGF2α, 16 cows were treated with 25 mg tromethamine dinoprost (Pronalgon F; Pfizer, Tokyo, Japan) for 21 days after natural ovulation. Five control cows were treated with sterile physiological saline. The follicle and corpus luteum (CL) development were monitored using a real-time ultrasound instrument. In addition, the plasma concentration of progesterone (P4) was determined. In nine of the 16 Pronalgon-treated cows, the first dominant follicle (1st DF), second dominant follicle (2nd DF), and third dominant follicle ovulated consecutively (group A). In five cows, the 1st and 2nd DFs ovulated consecutively (group B). The developing CL started to regress approximately 5 days after each ovulation without maturation in groups A and B. In the two remaining Pronalgon-treated cows, there was no further ovulation after natural ovulation (group C). In one cow in group C, the 1st DF became atretic and the 2nd DF became cystic with the diameter of the cystic follicle reaching 31.2 mm on Day 30. In another cow, the 1st DF became cystic with a diameter of 30.9 mm on Day 18. Although P4 began to increase after each ovulation in all of the Pronalgon-treated cows, it decreased immediately after each ovulation without a large increase, peaking at approximately 1 ng/mL. Furthermore, the number of days when P4 was >1 ng/mL from natural ovulation to Day 21 was 2.6 ± 0.7 days, which was significantly less than that in the control cows (16.0 ± 0.6 days). These results indicate that the long-term effect of PGF2α has an important role in ovulation of all dominant follicles and might induce cystic ovaries in cows.


Sujet(s)
Maladies des bovins/induit chimiquement , Dinoprost/effets indésirables , Kystes de l'ovaire/médecine vétérinaire , Follicule ovarique/effets des médicaments et des substances chimiques , Ocytociques/effets indésirables , Animaux , Bovins , Maladies des bovins/imagerie diagnostique , Corps jaune/imagerie diagnostique , Corps jaune/effets des médicaments et des substances chimiques , Industrie laitière , Dinoprost/usage thérapeutique , Femelle , Kystes de l'ovaire/induit chimiquement , Kystes de l'ovaire/imagerie diagnostique , Follicule ovarique/imagerie diagnostique , Follicule ovarique/physiologie , Ocytociques/usage thérapeutique , Progestérone/sang , Échographie
6.
Vet J ; 197(2): 358-62, 2013 Aug.
Article de Anglais | MEDLINE | ID: mdl-23422881

RÉSUMÉ

Various biochemical markers help to evaluate the state of bone turnover in humans and could be used during the peri-parturient period in dairy cows when calcium (Ca) metabolism changes dramatically. To investigate this, the peri-partum characteristics of serum bone-specific alkaline phosphatase (BAP) and urinary deoxypyridinoline (DPD) were investigated. Both serum BAP activity and urinary DPD concentrations were increased and demonstrated wide variability in younger animals, and these findings were consistent with other bone turnover markers. Around the time of parturition, serum Ca concentration and serum BAP activity in multiparous cows were significantly lower than in primiparous cows, but urinary DPD concentration was unchanged. The use of BAP as a bone formation marker appears to be valuable for evaluating bone remodelling status in cows, but the specificity of the test needs to be confirmed. The DPD/BAP ratio around parturition demonstrated a clear difference in bone turnover status between the two parity groups with multiparous cows demonstrating increased signs of bone resorption compared with primiparous cows, corresponding to the Ca requirement for milk production. In future studies, the applicability of the ratio of bone resorption marker to bone formation marker should be evaluated for bone turnover assessment.


Sujet(s)
Phosphatase alcaline/métabolisme , Acides aminés/urine , Os et tissu osseux/métabolisme , Bovins/physiologie , Période de péripartum/physiologie , Vieillissement , Phosphatase alcaline/génétique , Animaux , Femelle
7.
Theriogenology ; 79(5): 803-8, 2013 Mar 15.
Article de Anglais | MEDLINE | ID: mdl-23312720

RÉSUMÉ

To study ovarian responses to long-term intrauterine infusions of Trueperella pyogenes (T. pyogenes), 12 nonlacting Holstein cows were transcervically infused with 10 mL of a bacterial solution (8-19 × 10(8) colony-forming units/mL), and the uteri of another four cows (control) were similarly infused with sterile physiological saline. Infusions were done six times, every 3 days from Days 3 to 18 (Day 0 = day of spontaneous ovulation). Development of ovarian follicles and the CL were monitored with transrectal, real-time ultrasonography. In five of the experimentally infected cows (group A), the CL, which developed after Day 0, regressed without maturing, and the first dominant follicle (DF) ovulated (mean ± SEM interovulatory interval, 8.6 ± 0.5 days). In group A, plasma 13,14-dihydro-15-keto-PGF(2α) (PGFM) concentrations rose sharply on Day 6, but plasma progesterone concentrations did not increase substantially (as in the control) and were maintained at approximately 2.5 ng/mL after the first DF ovulated. In seven of the 12 infected cows (group B), the developing CL which formed after Day 0 matured and the second DF ovulated. However, the CL lifespan was shorter (P < 0.01) and the second DF ovulated earlier than in control (interovulatory interval, 16.0 ± 0.4 days and 22.3 ± 1.9 days; P < 0.01). Although there was no sharp increase in PGFM in group B, it tended to be high between Days 11 and 18. In conclusion, long-term, intrauterine infusions of T. pyogenes caused the CL to regress prematurely or to have a somewhat shorter lifespan because of release of endogenous PGF(2α).


Sujet(s)
Infections à Actinomycetales/médecine vétérinaire , Maladies des bovins/microbiologie , Corps jaune/microbiologie , Cycle oestral , Maladies de l'utérus/médecine vétérinaire , Utérus/microbiologie , Actinomycetaceae , Infections à Actinomycetales/complications , Infections à Actinomycetales/imagerie diagnostique , Animaux , Bovins , Maladies des bovins/imagerie diagnostique , Corps jaune/imagerie diagnostique , Corps jaune/anatomopathologie , Dinoprost/analogues et dérivés , Dinoprost/sang , Femelle , Ovulation/physiologie , Progestérone/sang , Échographie , Maladies de l'utérus/complications , Maladies de l'utérus/imagerie diagnostique , Maladies de l'utérus/microbiologie
8.
Reprod Med Biol ; 11(2): 91-94, 2012 Apr.
Article de Anglais | MEDLINE | ID: mdl-29699112

RÉSUMÉ

PURPOSE: The infusion of a bacterial solution into the uterus of rats raises the progesterone (P4) concentration in serum and extends diestrus. To understand the origin of the P4, we investigated the change in the P4 concentration of seven groups of rats for 5 days after the infusion of a bacterial solution. METHODS: The rats were divided into 7 treatment groups as follows: OvxBac, AdxBac, Ovx, Adx, LapBac, Lap, and Cont. In OvxBac, rats received both ovariectomy and bacterial inoculation into their uterus. In AdxBac, rats received both adrenalectomy and bacterial inoculation into their uterus. In Ovx, rats received only ovariectomy. In Adx, rats received only adrenalectomy. In LapBac, rats received only bacterial inoculation into their uterus. In Lap, rats received only laparotomy. In Cont, rats did not receive any treatment and acted as controls. RESULTS: The P4 concentration in all treatment groups was higher than in Cont on day 1 (the day following operation) and day 2. In Lap and LapBac, the P4 concentration was high on day 1 (>30 ng/mL) and maintained that value until day 2. In Adx and AdxBac, the P4 concentration was average on day 1 (approximately 25 ng/mL) and increased on day 2 to a value close to that of LapBac and Lap. In OvxBac, although the P4 concentration increased slightly on day 1 and day 2, it reached 22.5 ± 7.5 ng/mL on day 4. In AdxBac and LapBac, the P4 concentration on day 4 tended to be high. CONCLUSION: These results suggest that P4 is initially secreted from the ovaries and the adrenals in response to the surgical stress of laparotomy, and is later secreted from the adrenals due to the inflammatory reaction of the uterus.

9.
Can Vet J ; 52(6): 667-9, 2011 Jun.
Article de Anglais | MEDLINE | ID: mdl-22131586

RÉSUMÉ

This study investigated the long-term survival of a calf with cervical ectopia cordis that grew normally, became pregnant, and calved normally. The cow showed normal cardiac function and absence of peripheral circulation abnormalities. This paper documents antemortem characteristics of the affected cow.


Sujet(s)
Maladies des bovins/mortalité , Cardiopathies congénitales/médecine vétérinaire , Animaux , Bovins , Femelle , Cardiopathies congénitales/mortalité , Grossesse , Issue de la grossesse , Analyse de survie
10.
Dent Mater J ; 28(4): 419-25, 2009 Jul.
Article de Anglais | MEDLINE | ID: mdl-19721278

RÉSUMÉ

This study aimed to evaluate the effectiveness of self-etching and phosphoric acid-etching orthodontic adhesives for enamel bonding in simulated clinical conditions. By using two self-etching (Transbond Plus, TP; Beauty Ortho Bond, BB) and two acid-etching (Transbond XT, TX; Superbond Orthomite, SB) adhesives, orthodontic brackets were bonded on human premolars (n=10 for each adhesive). Ten teeth without bracket bonding, i.e., intact enamel surfaces, were used as control for SEM observation. After 7-day storage in lactic acid solution, bracket debonding force by means of debonding pliers, adhesive remnant index (ARI), and enamel surface morphology were examined. All the tested adhesives exhibited sufficient bond strength for clinical use. The ARI scores were almost the same among the four adhesives. In terms of SEM observation, the enamel surfaces in the control and TP groups showed a slight change after immersion in lactic acid solution, while the BB group showed less change on the enamel surface compared with the TP group. Meanwhile, the two acid-etching adhesives caused considerable demineralization. Taken together, these findings indicated that the action of self-etching systems was evidently more conservative.


Sujet(s)
Collage dentaire , Mordançage/méthodes , Brackets orthodontiques , Céments résine , Prémolaire , Décollement dentaire , Émail dentaire , Analyse du stress dentaire , Humains , Test de matériaux , Propriétés de surface
11.
J Vet Med Sci ; 70(1): 77-83, 2008 Jan.
Article de Anglais | MEDLINE | ID: mdl-18250576

RÉSUMÉ

To examine the ovarian response to Arcanobacterium pyogenes (A. pyogenes) in uterus, bacterial solution was infused into the uteri of cows, and the follicle and corpus luteum (CL) development were monitored with a real-time ultrasound instrument. In addition, the plasma concentrations of progesterone (P(4)) and 13, 14-dihydro-15-keto-PGF(2alpha) (PGFM) were determined. A 10 ml bacterial solution that contained A. pyogenes (8 to 15 x 10(8) CFU/ml) was infused into the uterus of eight cows transcervically three days after natural ovulation. As a control, sterile physiological saline was infused into 4 other cows. The dominant follicle developed normally in 8 cows after bacteria inoculation. In 4 of these 8 cows, the developing CL regressed, and the first wave dominant follicles, which normally become atretic, ovulated after the inoculation. In the remaining 4 cows, the CL did not regress. The PGFM concentration increased transiently in all 8 cows after the infusion. The mean PGFM concentration of the cows with a regressed CL was significantly lower (P<0.01) than that of the cows whose CLs did not regress. In the control cows, there was no regression of developing CLs, no ovulation of first wave dominant follicles and no transient increase in PGFM after the infusion of sterile physiological saline. These results show that infusion of A. pyogenes into the uterus did not affect folliculogenesis and might have induced PGF(2alpha) production from the uterus.


Sujet(s)
Actinomycetaceae/physiologie , Maladies des bovins/microbiologie , Endométrite/médecine vétérinaire , Infections bactériennes à Gram positif/médecine vétérinaire , Ovaire/physiologie , Animaux , Bovins , Maladies des bovins/métabolisme , Endométrite/métabolisme , Endométrite/microbiologie , Cycle oestral , Femelle , Infections bactériennes à Gram positif/métabolisme , Facteurs temps
12.
J Chem Phys ; 127(3): 031101, 2007 Jul 21.
Article de Anglais | MEDLINE | ID: mdl-17655423

RÉSUMÉ

Small-angle x-ray scattering measurements using a brilliant x-ray source revealed nanometer sized liquid droplets in a mist formed by ultrasonic atomization. Ultrasonic atomization of ethanol-water mixtures produced a combination of water-rich droplets of micrometer order and ethanol-rich droplets as small as 1 nm, which is 10(-3) times smaller than the predicted size. These sizes were also obtained for mists generated from the pure liquids. These results will help to clarify the mechanism of "ultrasonic ethanol separation," which has the potential to become an alternative to distillation.

13.
J Reprod Dev ; 51(4): 477-82, 2005 Aug.
Article de Anglais | MEDLINE | ID: mdl-15947457

RÉSUMÉ

In order to clarify the breeding capability of male raccoons in Japan, the testes of raccoons, a nuisance animal, collected in Kanagawa Prefecture and Hokkaido were histologically inspected. Furthermore, testosterone concentrations in their blood were measured. The testosterone concentrations increased in winter and the diameter of seminiferous tubules and the spermatogenetic score decreased in summer for the animals captured in Kanagawa Prefecture. For the animals captured in Hokkaido, the diameter of seminiferous tubules did not change and the decrease of the spermatogenetic score in summer was slight. As the above results show, there is a breeding season in male raccoons in Japan, and the reduction of testicular function in summer was greater in animals captured in Kanagawa Prefecture than in animals captured in Hokkaido.


Sujet(s)
Saisons , Testicule/anatomie et histologie , Animaux , Immunohistochimie , Mâle , Ratons laveurs , Dosage radioimmunologique , Canalicules séminifères/anatomie et histologie , Spermatogenèse , Testicule/physiologie , Testostérone/métabolisme
14.
Biomaterials ; 26(1): 101-8, 2005 Jan.
Article de Anglais | MEDLINE | ID: mdl-15193885

RÉSUMÉ

Hydrogen embrittlement of work-hardened Ni-Ti alloy has been examined in acidulated phosphate fluoride (APF) solutions. Upon immersion in a 2.0% APF solution with a pH of 5.0, tensile strength decreased markedly with immersion time. Moreover, the fracture mode changed from ductile to brittle due to brittle layer formation at the peripheral part of the cross section of the specimen. The amount of absorbed hydrogen increased linearly with immersion time, and it reached above 5000 mass ppm after 24 h. The hydrogen desorption temperature of the immersed specimens shifted from 450 degrees C to a lower temperature with immersion time. As the amount of absorbed hydrogen was larger than 500 mass ppm, the degradation of mechanical properties was recognized. Although the tensile properties and fracture mode scarcely change in a 0.2% APF solution, the slight reduction in hardness and hydrogen absorption of several hundreds mass ppm were observed. The results of the present study imply that work-hardened Ni-Ti alloy is less sensitive to hydrogen embrittlement compared with Ni-Ti superelastic alloy.


Sujet(s)
Fluorure de phosphate acidulé/composition chimique , Matériaux biocompatibles/composition chimique , Liquides biologiques/composition chimique , Hydrogène/composition chimique , Test de matériaux , Nickel/composition chimique , Fils orthodontiques , Titane/composition chimique , Absorption , Corrosion , Élasticité , Fluorures/composition chimique , Dureté , Essais de dureté , Propriétés de surface , Résistance à la traction
15.
Angle Orthod ; 74(4): 487-95, 2004 Aug.
Article de Anglais | MEDLINE | ID: mdl-15387026

RÉSUMÉ

The purpose of this study was to investigate the degradation in performance of four major alloys of orthodontic wires, namely nickel-titanium, beta titanium, stainless steel, and cobalt-chromium-nickel, caused by hydrogen absorption during short-term immersion in an acid fluoride solutions. The hydrogen-related degradation of orthodontic wires after immersion in 2.0% acidulated phosphate fluoride solution at 37 degrees C for 60 minutes was evaluated by a tensile test, scanning electron microscope observation, and hydrogen thermal desorption analysis. Upon immersion, the tensile strengths of the nickel-titanium and beta titanium wires decreased. Particularly, the nickel-titanium wire fractured before yielding, and the fracture mode changed from ductile to brittle. The amounts of absorbed hydrogen in the nickel-titanium and beta titanium wires were 200 and 100 mass ppm, respectively. On the other hand, the tensile strengths of the stainless steel and cobalt-chromium-nickel wires were only slightly affected by immersion. The results of this study suggest that degradation in performance of orthodontic wires of titanium alloys occurs because of hydrogen absorption even after a short-term immersion in fluoride solutions.


Sujet(s)
Fluorure de phosphate acidulé/toxicité , Alliage dentaire/composition chimique , Fils orthodontiques , Analyse thermique différentielle , Humains , Hydrogène/composition chimique , Test de matériaux , Microscopie électronique à balayage , Résistance à la traction/effets des médicaments et des substances chimiques
16.
J Reprod Dev ; 50(3): 361-7, 2004 Jun.
Article de Anglais | MEDLINE | ID: mdl-15226601

RÉSUMÉ

To investigate how uterine inflammation affects ovarian activity in rats, endometritis was induced and changes in the length of estrous cycle and serum concentrations of estradiol-17beta (E(2)) and progesterone (P(4)) were examined. A suspension of Staphylococcus aureus (bacterial solution) or iodine solution was infused into the uterine lumen at various estrous phases. When the bacterial solution was infused at estrus, metestrus, or the first day of diestrus, the following diestrus continued for 5 to 12 days. In the case of the iodine solution, regardless of the estrous phase of the infusion, the following diestrus continued for approximately 6 days. E(2) concentration after infusion of each solution did not fluctuate largely and remained at a low concentration (around 5 pg/ml). P(4) concentration was high (35-45 ng/ml) on the day following infusion, but decreased rapidly to base line values within a few days and remained thereafter at a low level (around 5 ng/ml). It is assumed that the endometritis caused by biological or chemical stimulation raises the concentration of P(4) to depress gonadotrophic hormone secretion, and hence this high P(4) concentration might inhibit the growth of ovarian follicles.


Sujet(s)
Cycle oestral/physiologie , Inflammation , Utérus/anatomopathologie , Animaux , Oestradiol/métabolisme , Femelle , Iode/pharmacologie , Ovaire/effets des médicaments et des substances chimiques , Ovaire/microbiologie , Ovaire/physiologie , Progestérone/métabolisme , Rats , Rat Wistar , Staphylococcus aureus/métabolisme , Facteurs temps , Utérus/métabolisme
17.
J Biomed Mater Res A ; 69(1): 105-13, 2004 Apr 01.
Article de Anglais | MEDLINE | ID: mdl-14999757

RÉSUMÉ

Hydrogen-related degradation of the mechanical properties of a Ni-Ti superelastic alloy has been examined by means of delayed fracture tests in acidic and neutral fluoride solutions and hydrogen thermal desorption analysis. Delayed fracture took place in both solutions; the time to fracture was shorter in the acidic solutions than in the neutral solutions with the same fluoride concentration. The time to fracture was reduced in both solutions when applied stress exceeded the critical stress for martensite transformation. In the acidic solutions, Ni-Ti superelastic alloy underwent general corrosion and absorbed substantial amounts of hydrogen. Fractographic features suggested that the delayed fracture in the acidic solutions was attributable to hydrogen embrittlement, whereas in the neutral solutions, a different fracture mode appeared associated with localized corrosion only in the vicinity of the fracture initiation area. In the neutral solutions, the amount of absorbed hydrogen was much less than that in the acidic solutions, and the delayed fracture was likely to be induced by active path corrosion accompanying hydrogen absorption. The results of the present study imply that the hydrogen-related degradation of performance of Ni-Ti superelastic alloys occurs in the presence of fluoride.


Sujet(s)
Fluorures/composition chimique , Hydrogène/composition chimique , Nickel/composition chimique , Titane/composition chimique , Corrosion , Électrochimie , Concentration en ions d'hydrogène , Test de matériaux , Microscopie électronique à balayage , Solutions , Contrainte mécanique , Résistance à la traction
18.
J Biomed Mater Res A ; 68(1): 150-8, 2004 Jan 01.
Article de Anglais | MEDLINE | ID: mdl-14661260

RÉSUMÉ

The fracture of commercial pure titanium in acid and neutral fluoride solutions has been examined by a sustained tensile-loading test and hydrogen thermal desorption analysis. It was found that the fracture of titanium occurred in neutral 2.0% NaF solution as well as in 2.0% acidulated phosphate fluoride (APF) solution. The time to fracture decreased with increasing applied stress in both 2.0% APF and 2.0% NaF solutions. In the case of the same applied stress, the time to fracture in the 2.0% APF solution was shorter than that in the 2.0% NaF solution. General corrosion was exhibited on the side surface of the tested specimens. The formation of sodium titanium fluoride was observed on the surface of the immersed specimens in the 2.0% APF solution. Hydrogen desorption of the tested specimen in the 2.0% APF solution was observed with a peak at approximately 600 degrees C. The amount of absorbed hydrogen was >300 mass ppm in the 2.0% APF solution under an applied stress for 24 h. The results of the present study imply that applying stress to titanium by immersing in fluoride solutions leads to the degradation of its mechanical properties.


Sujet(s)
Fluorures/composition chimique , Titane/composition chimique , Matériaux biocompatibles/composition chimique , Matériaux biomédicaux et dentaires , Hydrogène , Concentration en ions d'hydrogène , Microscopie électronique à balayage , Contrainte mécanique , Résistance à la traction , Thermodynamique
19.
Biochem Biophys Res Commun ; 305(3): 684-90, 2003 Jun 06.
Article de Anglais | MEDLINE | ID: mdl-12763048

RÉSUMÉ

Smad3 is an intracellular signaling molecule that mediates the signal from transforming growth factor-beta (TGF-beta) and activin receptors. In this study, we reveal hypomineralized enamel in mice with the targeted deletion of the Smad3 gene. The Smad3 (-/-) mice had chalky white incisor enamel, while the enamel of the wild-type or Smad3 (+/-) mice was yellow-brown. Histological analysis of the undecalcified sections showed that the enamel thickness of the maxillary incisors in the Smad3 (-/-) mice was similar to that of the wild-type and Smad3 (+/-) mice while that the enamel of the maxillary molars in Smad3 (-/-) mice was disrupted in places. Microcomputed tomography (microCT) analysis revealed that the mineralization of the maxillary incisors and mandibular molars in the Smad3 (-/-) mice showed significant reduction in the degree of mineralization when compared to that of the wild-type and Smad3 (+/-) mice. Scanning electron microscopic (SEM) analysis of the mandibular incisors revealed that the enamel surface of the Smad3 (-/-) mice was irregular and disrupted in places and showed images similar to decalcified mature enamel. The histological analysis of the decalcified sections showed that distinct morphological changes in the ameloblasts at the secretory and maturational stages were not observed between the Smad3 (-/-) and Smad3 (+/-) or wild-type mice, while the enamel matrix was observed in the decalcified sections of the mandibular molars in the Smad3 (-/-) mice. These results suggested that Smad3 was required for enamel biomineralization, and TGF-beta and activin signaling might be critical for its process.


Sujet(s)
Calcification physiologique , Protéines de liaison à l'ADN/physiologie , Émail dentaire/croissance et développement , Transactivateurs/physiologie , Animaux , Protéines de liaison à l'ADN/génétique , Émail dentaire/anatomie et histologie , Émail dentaire/ultrastructure , Souris , Souris de lignée C57BL , Souris knockout , Microscopie électronique à balayage , Protéine Smad-3 , Tomodensitométrie , Transactivateurs/génétique
20.
J Biomed Mater Res A ; 65(2): 182-7, 2003 May 01.
Article de Anglais | MEDLINE | ID: mdl-12734810

RÉSUMÉ

Hydrogen embrittlement of Ni-Ti superelastic alloy in a fluoride solution (0.2% APF) has been investigated by means of a tensile test (after immersion) and hydrogen thermal desorption analysis. Upon immersion, the tensile strength of the alloy decreased to the critical stress level of martensite transformation. Hydrogen desorption of the immersed specimens appeared with a peak at around 500 degrees C. The amount of absorbed hydrogen in the alloy ranged from 100 to 1000 mass ppm when immersed in the fluoride solution for 2 to 24 h. The immersion in the fluoride solution led to the degradation of mechanical properties due to hydrogen embrittlement. The results of the present study imply that one reason that Ti and its alloys fracture in the oral cavity is the fact that hydrogen is absorbed in a fluoride solution, such as prophylactic agents.


Sujet(s)
Alliage dentaire/composition chimique , Hydrogène , Nickel/composition chimique , Titane/composition chimique , Élasticité , Fluorures , Microscopie électronique à balayage , Solutions , Contrainte mécanique , Résistance à la traction , Thermodynamique
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