Effect of different dosages of PG-600 on ovulation and pregnancy rates in ewes during the breeding season.

This study compared the reproductive effects of different dosages of PG-600 (Intervet/Merck Animal Health, Madison, NJ) during the breeding season of ewes. PG-600 is a single-dose injectable product labeled for estrous induction in swine, containing equine chorionic gonadotropin (80 IU/mL) and human chorionic gonadotropin (40 IU/mL). PG-600 is routinely used off-label for out-of-season estrous induction in sheep. However, at the most common dose administered to ewes (5 mL), PG-600 is likely to overstimulate the ovaries, resulting in reduced pregnancy rates. Following estrous synchronization with intravaginal progesterone and cloprostenol, Polypay ewes were treated with 5 mL PG-600 (T1; n = 8), 1.5 mL PG-600 (T2; n = 8), or 5 mL saline (C; n = 8) and then mated to rams. Jugular vein samples were collected prior to the PG-600 injection (0 hr) and at 2, 4, 8, 12, and 24 hr after injection. Serum estradiol-17ß was determined by chemiluminescence and among groups using repeated measures analysis of covariance. Ovulation and pregnancy rates were determined by transrectal ultrasonography and compared by one-way ANOVA and chi-square, respectively. Estradiol-17ß concentrations were greater in T1 compared to T2 and C (P < 0.001). Ovulation rate was greater (P < 0.001) but pregnancy rate was lower (P < 0.001) in the T1 compared to C and T2. These data confirm that a 5 mL dose of PG-600 administered to ewes during the breeding season overstimulates the ovaries, which may then reduce fertilization or embryo survival. Future research will focus on the effects of different dosages of PG-600 on pregnancy rate of ewes during the nonbreeding season.

Chitosan dressing provides hemostasis in swine femoral arterial injury model.

OBJECTIVE: Chitosan dressings have been shown to be effective in improving survival of severe parenchymal injuries in an animal model and in treating prehospital combat casualties. Our goal was to test the efficacy of chitosan acetate dressings in providing durable hemostasis in a high-flow arterial wound model. METHODS: A proximal arterial injury was created with 2.7-mm vascular punches in both femoral arteries of fourteen anesthetized swine. By using a crossover design, 48-ply gauze (48PG) or a chitosan dressing (HC) was applied with pressure to the injury for 3 minutes and then released. If hemostasis was not maintained for 30 minutes, a second identical attempt was made by using the same dressing type. If hemostasis was still not achieved, the dressing was considered an acute failure and the alternate dressing type was applied. If failure of hemostasis occurred between 30 and 240 minutes after application, the dressing was considered a chronic failure and the artery was ligated. RESULTS: All 25/25 (100%) of the HC tests and 3/14 (21%) of the 48PG maintained hemostasis for 30 minutes. At 240 minutes, 21/25 (84%) of the HC tests and 1/14 (7%) of the 48PG maintained hemostasis. Statistical analysis by Fischer's exact test shows a significant (p < 0.001) difference in hemostatic efficacy between the 48PG and HC groups in this model, both at 30 minutes and at 240 minutes. CONCLUSION: Chitosan acetate hemorrhage control dressings provided superior hemostasis to 48 ply gauze in high inguinal femoral arterial injuries. Chitosan-based dressings may provide prehospital treatment options for hemostasis in patients with severe hemorrhagic arterial injuries.

Intraovarian actions of anti-angiogenic agents disrupt periovulatory events during the menstrual cycle in monkeys.

To determine if anti-angiogenic agents disrupt primate ovarian function, vehicle or a general angiostatic compound (TNP-470), specific antagonists of vascular endothelial growth factor (soluble VEGF receptor-1, sVEGFR-1; anti-VEGF monoclonal antibody, VEGF Ab) and/or an angiopoietin antagonist (Ang-2) were administered to rhesus monkeys: (1) locally via injection into the preovulatory follicle at midcycle or the developing corpus luteum at the midluteal phase; or (2) systemically via subcutaneous injection in the early follicular phase or at midcycle during the natural menstrual cycle. Compared to controls, intrafollicular injection of TNP-470 or sVEGFR-1 decreased circulating progesterone (P) levels in the subsequent luteal phase. Treatment with sVEGFR-1, but not TNP-470, also decreased the incidence of ovulation. Intrafollicular injection of Ang-2 also prevented ovulation, as well as any functional luteal phase. In the absence of elevated P, serum estradiol levels rose to peak levels 11-12 days post-Ang-2 treatment, at which time another large antral follicle was observed on the contralateral (noninjected) ovary. Intraluteal and systemic injection of VEGF antagonists alone or with Ang-2 had minimal effects. Thus, anti-angiogenic factors can act locally in the primate follicle to disrupt the gametogenic (oocyte release) and endocrine (steroid) functions of the ovary. However, further studies are needed to optimize delivery of angiogenic agents before they can be meaningfully evaluated as possible contraceptive agents.

Injection of soluble vascular endothelial growth factor receptor 1 into the preovulatory follicle disrupts ovulation and subsequent luteal function in rhesus monkeys.

Remarkable changes in vascular permeability and neovascularization occur within the ovulatory, luteinizing follicle. To evaluate the importance of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) in periovulatory events, sequential experiments were designed in which vehicle (PBS/0.1% BSA; controls, n = 13) or a low dose (1.5 micro g; n = 4) or a high dose (7.5 micro g; n = 4) of a VEGF antagonist, soluble VEGF receptor 1 (sVEGFR1) chimera, was injected directly into the preovulatory follicle of rhesus monkeys the day before (Day -1) or the day of (Day 0) the midcycle LH surge during spontaneous menstrual cycles. After vehicle injection, animals typically exhibited patterns and levels of serum progesterone (P(4)) that were comparable to those of untreated animals in our colony. Following low-dose sVEGFR1 injection, serum P(4) levels were diminished in two of four animals from the early to midluteal phase, but were similar to vehicle controls thereafter. In contrast, high-dose sVEGFR1 injection decreased serum P(4) levels throughout the luteal phase compared with levels in controls (P < 0.05), but it did not cause premature menstruation. Control follicles displayed indices of rupture (protruding stigmata) and luteinization. However, sVEGFR1-injected follicles exhibited signs of distension (torn surface epithelium/tunica albuginea) and luteinization, but not necessarily timely ovulation. Histological evaluation of serial sections from ovaries removed on Day 3 after treatment revealed that all (n = 3) vehicle-injected follicles ovulated, whereas half (n = 3 of 6) the sVEGFR1-injected follicles failed to ovulate and still contained an oocyte in the antrum. No appreciable differences were apparent between treatment groups in numbers of cells in luteal tissue (Day 3 or 6 after treatment) that stained positive for immunochemical or histochemical markers of proliferative (Ki67), endothelial (platelet endothelial cell adhesion molecule 1), and steroidogenic (3beta-hydroxysteroid dehydrogenase) cells. However, there was a dose-dependent increase (P < 0.05) in extracellular space in the corpus luteum by midluteal phase in sVEGFR1-treated animals. The data suggest that acute exposure to a VEGF antagonist can impair ovulation, and the subsequent development and functional capacity of the primate corpus luteum. The results are consistent with a critical role for VEGF in normal ovarian function during the periovulatory interval in primates.

Injection of antiangiogenic agents into the macaque preovulatory follicle: disruption of corpus luteum development and function.

Ovulation and conversion of the follicle into the corpus luteum involve remarkable changes in vascular permeability and neovascularization of the luteinizing granulosa layer. To evaluate the importance of these vascular events in follicle rupture and luteal development, sequential experiments were designed in which vehicle or angiogenic inhibitors (TNP-470 or angiostatin) were injected directly into the preovulatory follicle of rhesus monkeys during spontaneous menstrual cycles. After control injections, 13 of 14 animals exhibited serum levels of progesterone (P) during the subsequent luteal phase that were comparable to untreated animals in our colony. Following low-dose (400 pg/mL) TNP-470, serum P levels increased normally until d 8 of the luteal phase, but then declined prematurely by d 9 (p < 0.05 compared to controls) and remained below controls until menses. Following high-dose (2 microg/mL) TNP-470, serum P levels were diminished in the early luteal phase (d 3-5; p < 0.05 compared to controls), but reached typical levels at mid luteal phase, only to decline prematurely by d 9 (p < 0.05) and remain low until menses. Control ovaries displayed indices of follicle rupture (protruding stigmata) and luteinization. TNP-470-treated ovaries exhibited signs of distension (torn surface epithelium/tunica albuginea) and luteinization; however, a well-formed stigmata was not observed. A "trapped" oocyte was not observed in serial sections of developing corpora lutea from control or TNP-470-treated animals. However, the early corpus luteum of TNP-470-injected ovaries contained pockets of excessive numbers of blood cells that were absent in controls. Angiostatin did not alter serum P levels or ovarian morphology compared to controls. These data suggest that acute exposure to the antiangiogenic agent TNP-470 impairs the development and functional capacity of the primate corpus luteum in a dose-dependent manner. The results are consistent with a critical role for angiogenesis in cyclic ovarian function in primates.