Pharmacokinetics of intravenous and transdermal fentanyl in alpacas

The purpose of the study was to determine pharmacokinetics of fentanyl after intravenous (i.v.) and transdermal (t.d.) administration to six adult alpacas. Fentanyl was administered i.v. (2 μg/kg) or t.d. (nominal dose: 2 μg kg^?1 hr^?1). Plasma concentrations were determined using liquid chromatography–mass spectrometry. Heart rate and respiratory rate were assessed. Extrapolated, zero‐time plasma fentanyl concentrations were 6.0 ng/ml (1.7–14.6 ng/ml) after i.v. administration, total plasma clearance was 1.10 L hr^?1 kg^?1 (0.75–1.40 L hr^?1 kg^?1), volumes of distribution were 0.30 L/kg (0.10–0.99 L/kg), 1.10 L/kg (0.70–2.96 L/kg) and 1.5 L/kg (0.8–3.5 L/kg) for V₁, V₂, and V_ss, respectively. Elimination half‐life was 1.2 hr (0.5–4.3 hr). Mean residence time (range) after i.v. dosing was 1.30 hr (0.65–4.00 hr). After t.d. fentanyl administration, maximum plasma fentanyl concentration was 1.20 ng/ml (0.72–3.00 ng/ml), which occurred at 25 hr (8–48 hr) after patch placement. The area under the plasma fentanyl concentration‐vs‐time curve (extrapolated to infinity) after t.d. fentanyl was 61 ng*hr/ml (49–93 ng*hr/ml). The dose‐normalized bioavailability of fentanyl from t.d. fentanyl in alpacas was 35.5% (27–64%). Fentanyl absorption from the t.d. fentanyl patch into the central compartment occurred at a rate of approximately 50 μg/hr (29–81 μg/hr) between 8 and 72 hr after patch placement.     

Gas and short‐chain fatty acid production from feeds commonly fed to red deer (Cervus elaphus L.) and incubated with rumen inoculum from red deer and sheep

Efficient red deer supplementary feeding depends on estimations of the nutritive value of offered feeds, frequently estimated with the use of equations derived from domestic ruminants. The aim of this study was to compare the 24‐hour in vitro true dry matter degradability (ivTD₂₄), in vitro gas production (GP) kinetic parameters, GP in 24 hr of incubation (GAS₂₄) and short‐chain fatty acid (SCFA) and microbial biomass (MBS) produced after 24‐hour incubation of feeds in inoculum prepared from sheep and red deer rumen fluid. Eleven feeds, frequently consumed by red deer in Slovenia, which occur either naturally (two fresh grasses, chestnut fruits and common and sessile oak acorns) or are fed as winter supplemental feeds (two grass hays, two grass silages, apple pomace, fresh sugar beetroot), were investigated. The in vitro GP kinetic parameters, GAS₂₄ and ivTD₂₄, did not differ between animal species. Amounts of SCFAs were greater (p < 0.05) when feeds were incubated in sheep inoculum, while molar proportions of acetic and propionic acids did not differ. Molar proportions of butyric acid produced during incubation of high fibre feeds did not differ between animal species, but were higher (p < 0.05) when feeds high in starch or sugar were incubated in red deer inoculum. Greater production of SCFA by sheep rumen microbes suggests better coverage of host animal with energy precursors, while greater production of MBS by red deer rumen microbes suggests better coverage of host animal with protein. Results also suggest that rumens of sheep and red deer are inhabited by different microbial communities, which did not affect the extent of in vitro GP and degradation of feeds used in the present experiment. However, the possibility exists that the divergent nutrient use could be a consequence of different priming by different feeds of the donor animal diets.     

Insulin-like growth factor-I concentration in Holstein female cattle: variations with age, stage of lactation and growth hormone-releasing factor administration

Plasma insulin-like growth factor-I (IGF-I) concentrations were monitored in Holstein females through different periods of their growth, lactation and after acute or chronic growth hormone-releasing factor (GRF) administration. Plasma samples were radioimmunoassayed using a human IGF-I antibody after a 24 hr incubation in a HCl(.1N)-glycine(.2M) buffer (pH 2). In a first study, IGF-I concentrations were measured in Holstein females of different ages and(or) stages of lactation (n = 6 per group). The IGF-I concentrations in newborn calves (102.0 +/- 11.3 ng/ml) markedly decreased (P less than .01) in 1 mo old animals (50.2 +/- 7.1 ng/ml), then increased (P less than .01) to 137.0 +/- 5.1 and 137.4 +/- 11.0 ng/ml in 6 and 10 mo old heifers, respectively. In dairy cows, IGF-I concentrations were low 24 hr post-partum (44.7 +/- 7.6 ng/ml) and then increased (P less than .05) to remain stable throughout lactation (91.3 +/- 4.9, 92.8 +/- 12.9, 96.1 +/- 7.6, 90.7 +/- 8.8 ng/ml at 2, 3, 6 and 9 mo of lactation, respectively). There was a further increase (P less than .05) to 113.7 +/- 3.1 ng/ml during the dry period. In a second trial, blood samples were collected from lactating dairy cows every 2 hr for 24 hr following a sc injection of saline (n = 4) or human (h) GRF (1-29)NH2 (10 micrograms/kg BW, n = 4). The IGF-I peak concentration was reached on average 10 hr after the GRF injection and was higher (P less than .01) in treated cows than in control cows (135.4 vs 86.9 +/- 16.2 ng/ml). In the last trial, daily sc injections of 10 micrograms of hGRF(1-29)NH2 per kg BW to dairy cows (252 days of lactation) for 57 days, which increased milk production by 14% (2 kg/day), also increased (P less than .01) IGF-I concentration: 127.1 +/- 5.3 and 118.0 +/- 1.6 vs 90.7 +/- 4.7 and 96.0 +/- 5.0 ng/ml on days 29 and 57 of treatment for treated (n = 9) and control (n = 8) cows, respectively. Thus, the IGF-I concentration in dairy cattle varies with age and stage of lactation, and is increased by GRF administration in lactating dairy cows.     

The early events of infection with Theileria parva in cattle: infectivity for cattle of leukocytes incubated in vitro with sporozoites

Leukocytes were isolated from bovine blood and, after short periods of incubation in vitro with sporozoites of Theileria parva, were washed thoroughly, and their infectivity tested in autologous and allogeneic hosts. Using a standard inoculum of 10(6) viable cells, it was found that, after incubation in vitro for either 1 or 24 h, the cells initiated lethal infections in autologous cattle, but failed to infect allogeneic animals. Autologous and allogeneic erythrocytes and mouse lymphocytes similarly incubated with sporozoites failed to infect cattle. The supernatant from bovine lymphocyte suspensions incubated with sporozoites for 1 h produced lethal infections whereas after 24 h of incubation the supernatant was non-infective. All cattle which did not develop detectable infection were fully susceptible to subsequent challenge with a stabilate of sporozoites. By inoculating cattle with graded doses of autologous blood leukocytes which had been incubated for 24 h with sporozoites, it was found that as few as 2 X 10(3) cells gave rise to infection. The results indicate that this approach can be used to evaluate different cell populations as targets for infection and transformation by sporozoites of T. parva.     

Pharmacokinetics in plasma and alveolar regions of a healthy calf intramuscularly administered a single dose of orbifloxacin

This study analyzed the pharmacokinetics of orbifloxacin (OBFX) in plasma, and its migration and retention in epithelial lining fluid (ELF) and alveolar cells within the bronchoalveolar lavage fluid (BALF). Four healthy calves received a single dose of OBFX (5.0 mg/kg) intramuscularly. Post-administration OBFX dynamics were in accordance with a non-compartment model, including the absorption phase. The maximum concentration (C_max) of plasma OBFX was 2.2 ± 0.1 μg/ml at 2.3 ± 0.5 hr post administration and gradually decreased to 0.3 ± 0.2 μg/ml at 24 hr following administration. The C_max of ELF OBFX was 9.3 ± 0.4 μg/ml at 3.0 ± 2.0 hr post administration and gradually decreased to 1.2 ± 0.1 μg/ml at 24 hr following administration. The C_max of alveolar cells OBFX was 9.3 ± 2.9 μg/ml at 4.0 hr post administration and gradually decreased to 1.1 ± 0.2 μg/ml at 24 hr following administration. The half-life of OBFX in plasma, ELF, and alveolar cells were 6.9 ± 2.2, 7.0 ± 0.6, and 7.8 ± 1.6 hr, respectively. The C_max and the area under the concentration-time curve for 0–24 hr with OBFX were significantly higher in ELF and alveolar cells than in plasma (P<0.05). These results suggest that OBFX is distributed and retained at high concentrations in ELF and alveolar cells at 24 hr following administration. Hence, a single intramuscular dose of OBFX (5.0 mg/kg) may be an effective therapeutic agent against pneumonia.     

Serum oxytetracycline concentrations in African elephant (Loxodonta africana) calves after long-acting formulation injection.

Serum oxytetracycline pharmacokinetics were studied in 18 African elephant (Loxodonta africana) calves. Each elephant received separate injections of oxytetracycline at approximately 18 mg/kg i.m. and 8 mg/kg i.v. in a cross-over study. Blood samples were drawn at 0, 24, 48, 72, and 96 hr postinjection. An additional sample was drawn 110 hr before the animals were reinjected in the cross-over study and a final blood sample was drawn 48 hr after the second dose. No lameness or stiffness was observed following i.m. injections. Serum oxytetracycline concentrations >0.5 microg/ml were present 48 hr after initial dosing for all elephants (i.m., i.v., high or low dosage). Only elephants given the high i.m. dosage (18 mg/kg) maintained levels >0.5 microg/ml 72 hr postinjection. No significant difference in serum oxytetracycline concentration with time was observed between the groups given different i.v. dosages. These studies demonstrated that quantifiable serum oxytetracycline concentrations can be maintained in young African elephants with a low-dosage multidose i.m. regimen.     

The effect of pulsatile gonadotropin-releasing hormone and estradiol administration on luteinizing hormone and follicle-stimulating hormone concentrations in pituitary stalk-sectioned ovariectomized pony mares

Hourly pulses of gonadotropin-releasing hormone (GnRH) or bi-daily injections of estradiol (E2) can increase luteinizing hormone (LH) secretion in ovariectomized, anestrous pony mares. However, the site (pituitary versus hypothalamus) of positive feedback of estradiol on gonadotropin secretion has not been described in mares. Thus, one of our objectives involved investigating the feedback of estradiol on the pituitary. The second objective consisted of determining if hourly pulses of GnRH could re-establish physiological LH and FSH concentrations after pituitary stalk-section (PSS), and the third objective was to describe the declining time trends of LH and FSH secretion after PSS. During summer months, ovariectomized pony mares were divided into three groups: Group 1 (control, n = 2), Group 2 (pulsatile GnRH (25 μg/hr), n = 3), and Group 3 (estradiol (5 mg/12 hr), n = 3). All mares were stalk-sectioned and treatment begun immediately after stalk-section. Blood samples were collected every 30 min for 8 h on the day before surgery (DO) and 5 d post surgery (D5) to facilitate the comparison of gonadotropin levels before and after pituitary stalk-section. Additionally, jugular blood samples were collected every 12 hr beginning the evening of surgery, allowing for evaluation of the gonadotropin secretory time trends over the 10 d of treatment. On Day 10, animals were euthanized to confirm pituitary stalk-section and to submit tissue for messenger RNA analysis (parallel study). Plasma samples were assayed for LH and FSH by RIA. Mean LH secretion decreased from Day 0 to Day 5 in Groups 1 and 3, whereas LH secretion tended (P < 0.08) to decrease in Group 2 mares. On Day 5, LH was higher (P < 0.01) in Group 2 (17.26 ± 3.68 ng/ml; LSMEANS ± SEM), than either Group 1 (2.65 ± 4.64 ng/ml) or group 3 (4.28 ± 3.68 ng/ml). Group 1 did not differ from Group 3 on Day 5 (P < 0.40). Similarly, mean FSH levels decreased in all groups after surgery, yet Group 2 mares had significantly (P < 0.001) higher FSH concentrations (17.66 ± 1.53 ng/ml) than Group 1 or Group 3 (8.34 ± 1.84 and 7.69 ± 1. 63 ng/ml, respectively). Regression analysis of bi-daily LH and FSH levels indicated that the time trends were not parallel. These findings indicate: 1) Pituitary stalk-section lowered LH and FSH to undetectable levels within 5 d after surgery, 2) pulsatile administration of GnRH (25 μg/hr) maintained LH and FSH secretion, although concentrations tended to be lower than on Day 0, and 3) E2 did not stimulate LH or FSH secretion.     

Pharmacokinetics of posaconazole in koalas (Phascolarctos cinereus) after intravenous and oral administration

The pharmacokinetic profile of posaconazole in clinically normal koalas (n = 8) was investigated. Single doses of posaconazole were administered intravenously (i.v.; 3 mg/kg; n = 2) or orally (p.o.; 6 mg/kg; n = 6) with serial plasma samples collected over 24 and 36 hr, respectively. Plasma concentrations of posaconazole were quantified by validated high‐performance liquid chromatography. A noncompartmental pharmacokinetic analysis of data was performed. Following i.v. administration, estimates of the median (range) of plasma clearance (CL) and steady‐state volume of distribution (V_ss) were 0.15 (0.13–0.18) L hr^?1 kg^?1 and 1.23 (0.93–1.53) L/kg, respectively. The median (range) elimination half‐life (t_1/2) after i.v. and p.o. administration was 7.90 (7.62–8.18) and 12.79 (11.22–16.24) hr, respectively. Oral bioavailability varied from 0.43 to 0.99 (median: 0.66). Following oral administration, maximum plasma concentration (C_max; median: 0.72, range: 0.55–0.93 μg/ml) was achieved in 8 (range 6–12) hr. The in vitro plasma protein binding of posaconazole incubated at 37°C was 99.25 ± 0.29%. Consideration of posaconazole pharmacokinetic/pharmacodynamic (PK/PD) targets for some yeasts such as disseminated candidiasis suggests that posaconazole could be an efficacious treatment for cryptococcosis in koalas.     

Microencapsulation of bovine spermatozoa

Two experiments were conducted to examine the efficacy of microencapsulation of bovine spermatozoa for use in artificial insemination. In Exp. 1, sperm were encapsulated at three different concentrations (45, 90 and 180 X 10(6) sperm/ml) in either .75- or 1.5-mm (diameter) microcapsules and incubated in vitro for 24 h at 37 C. Unencapsulated samples of each concentration served as controls. Capsule contents were evaluated for percentage of sperm motility and intact acrosomes at 2, 12 and 24 h of incubation. Capsule fragility was evaluated after 24 h incubation. Viability of spermatozoa was not influenced by sperm concentration or capsule size, and compared with controls, cellular injury after encapsulation was not apparent. Fragility of capsules was unaffected by capsule size; however, as the sperm concentration increased, integrity of the capsules decreased (P less than .05). In Exp. 2, using frozen-thawed semen, the effect of egg yolk content, presence of glycerol and viability of spermatozoa on the success of microencapsulation was measured. The extender was 2.9% sodium citrate with glycerol (7% v/v) and either 0, 5, 10 or 15% egg yolk (v/v). Uniformity of capsules in size and shape was evaluated subjectively. Capsule integrity and uniformity were unaffected by glycerol, sperm viability or egg yolk level up to 10% v/v; however, encapsulation of spermatozoa in 15%-yolk buffer increased the heterogeneity in capsule size and shape. Viability of encapsulated spermatozoa was maximal for extenders containing 10 or 15% yolk v/v. Reduced viability for the 5% yolk extender was due to pre-encapsulation injury associated with freezing. Microencapsulation procedures are compatible with sperm viability and can be adapted to an acceptable extender system used in artificial insemination.     

Bioavailability of suppository acetaminophen in healthy and hospitalized ill dogs

To determine the plasma pharmacokinetics of suppository acetaminophen (APAP) in healthy dogs and clinically ill dogs. This prospective study used six healthy client‐owned and 20 clinically ill hospitalized dogs. The healthy dogs were randomized by coin flip to receive APAP orally or as a suppository in crossover study design. Blood samples were collected up to 10 hr after APAP dosing. The hospitalized dogs were administered APAP as a suppository, and blood collected at 2 and 6 hr after dosing. Plasma samples were analyzed by ultra‐performance liquid chromatography with triple quadrupole mass spectrometry. In healthy dogs, oral APAP maximal concentration (C_MAX=2.69 μg/ml) was reached quickly (T_MAX=1.04 hr) and eliminated rapidly (T1/2 = 1.81 hr). Suppository APAP was rapidly, but variably absorbed (C_MAX=0.52 μg/ml T_MAX=0.67 hr) and eliminated (T_1/2 = 3.21 hr). The relative (to oral) fraction of the suppository dose absorbed was 30% (range <1%–67%). In hospitalized ill dogs, the suppository APAP mean plasma concentration at 2 hr and 6 hr was 1.317 μg/ml and 0.283 μg/ml. Nonlinear mixed‐effects modeling did not identify significant covariates affecting variability and was similar to noncompartmental results. Results supported that oral and suppository acetaminophen in healthy and clinical dogs did not reach or sustain concentrations associated with efficacy. Further studies performed on different doses are needed.     

Synergism and diurnal variations of human growth hormone-releasing factor (1-29)NH2 and thyrotropin-releasing factor on growth hormone release in dairy calves

Sixteen male Holstein calves averaging 168 kg body weight (BW) were used to determine the effects of human growth hormone-releasing factor (1–29)NH₂ (hGRF (1–29)NH₂; .22 μg/kg BW), thyrotropin-releasing factor (TRF; .165 μg/kg BW) or hGRF (1–29)NH₂ plus TRF (.22 and .165 μg/kg BW, respectively) on growth hormone (GH) release in animals exposed to 16 hr of light (L): 8 hr of dark (D) (lights on at 0100 hr) and hGRF plus TRF (.22 and .165 μg/kg BW, respectively) in animals exposed to 8L:16D (lights on at 0900 hr). For each treatment, times of iv injection were 0400, 1000, 1600 and 2200 hr. In animals exposed to 16L:8D, average GH peaks reached after hGRF (1–29)NH₂ or TRF injections were 49.7 and 32.0 ng/ml while the area under the GH response curve (AUC) were 1247 and 1019 ng/ml^*min, respectively. There was no significant effect of times of injection on GH release following the separate injection of hGRF (1–29)NH₂ or TRF. In animals exposed to 16L:8D, GH peaks and AUC after hGRF plus TRF injections were 226.4, 189.2 and 116.8 ng/ml, and 4340, 3660 and 2415 ng/ml^*min at 0400, 1000 and 1600 hr (lights on), respectively but only 42.3 ng/ml and 1692 ng/ml^*min at 2200 hr (lights off). In animals exposed to 8L:16D, GH levels and AUC after hGRF plus TRF injections reached 177.5 and 180.5 ng/ml, and 2759 and 3704 ng/ml^*min at 1000 and 1600 hr (lights on) but only 84.0 and 72.7 ng/ml, and 1544 and 1501 ng/ml^*min at 0400 and 2200 hr (lights off), respectively. These results demonstrated that hGRF (1–29)NH₂ and TRF can act in synergy to potentiate GH release in dairy calves. This synergistic action occurred only when both peptides were injected during the lighted phase of short and long day photoperiods.     

Epigallocatechin‐3‐gallate (EGCG) and green tea polyphenols do not improve stallion semen parameters during cooling at 4°C

Stallion semen storage for artificial insemination is mainly based on liquid cooled storage. In many stallions this technique maintains sperm quality for an extended period of time (24–72 hr) at 7°C. While this technique is commonly used in the horse industry, there can be a decline in fertility in some stallions, due to an inability of their sperm to tolerate the cool storage process. The aim of the present work was to evaluate the effect of two natural antioxidants (epigallocatechin‐3‐gallate (EGCG) at 20, 60 and 120 μm and green tea polyphenols, and p at .001, .01 and .1 mg/ml) on some sperm parameters (sperm motility, viability/acrosome integrity and DNA quality) in extended semen immediately after its collection (T0) and after 2, 6, 24 and 48 hr of cool storage. Two ejaculates from three trotter stallions were analysed after 48 hr of storage at 4°C. No beneficial effect on the analysed parameters was observed: the two antioxidants were not able to improve sperm quality after 48 hr of storage. These results are in agreement with previous findings on the effect of different antioxidants reported by other researches, who have demonstrated that stallion semen keeps good antioxidant capacity after dilution for 24 hr. In conclusion, the positive effect exerted by antioxidant molecules in other species is not confirmed in the equine one.     

Progesterone production in granulosa cells of the domestic fowl: effects of incubation media, pH, cell density and some other factors

The objective of this study was to determine the optimal conditions for the short term incubation of chicken granulosa cells. Compared to mechanically-dispersed cells, collagenase-treatment yielded granulosa cells of greater viability and responsiveness to ovine LH (oLH) stimulation. The rate of progesterone secretion by enzyme-dispersed chicken granulosa cells was subsequently compared in five different culture media during incubation periods of up to 24 hr. Under room air as the gas phase, Medium 199 (M199) containing Hank's salts and Ham's F-12 medium (F-12) were the most effective, whereas Krebs-Ringer bicarbonate-buffered glucose solution (KRBG) and Dulbecco's medium were the poorest. When pH and the ionic strength of KRBG was maintained by continuous gassing with O₂:CO₂ (95:5), progesterone production was similar to that obtained with Hepes-buffered M199. The pH optimum was found to be 7.4, although within the range of 6.6–8.5 granulosa cells remained responsive to LH stimulation. The optimal cell density was observed to be 1 × 10⁴ to 5 × 10⁵/ml. Although time course studies showed that both basal and stimulated progesterone production peaked by about 12 hr of incubation regardless of the media composition, the amounts released were significantly greater in M199 and F-12 during more prolonged (up to 24 hr) incubations. Glucose, a key medium ingredient for hormone-stimulated steroidogenesis, could be replace by pyruvate. On the other hand, lactate was inhibitory. It is concluded that the mature ovarian follicles of the domestic fowl are an excellent source of pure granulosa cells that can be obtained in high yield after a brief treatment with collagenase. These cells remain viable up to 24 hr and continue to produce large amounts of progesterone in response to LH when incubated in an appropriate medium and at optimal cell density.     

Effects of inactive parapoxvirus ovis on cytokine levels in rats

The aim of this study is to determine the effects of iPPOV on pro-inflammatory and anti-inflammatory cytokine levels in rats. iPPOV (1 ml/rat) was administered intraperitoneal route to 49 rats, except for 7 rats (Control, 0 group). Serum samples were collected from 7 rats at 1st, 2nd, 4th, 8th, 12th, 16th and 24th hr after treatments. Levels of TNF-α, IL-6, IL-12 and IL-10 were determined using ELISA. Administration of iPPOV stimulated TNF-α (16th and 24th hr) and IL-6 (12th, 16th and 24th hr) synthesis and caused fluctuations in IL-10 and IL-12 concentrations. In conclusion, increased cytokine levels could be attributed to immunomodulatory activity of iPPOV, however, detailed studies are required to fully understand effects of iPPOV on immune system.     

Ontogenies of messenger RNA encoding tissue inhibitor of metalloproteinases 1 and 2 within bovine periovulatory follicles and luteal tissue

Tissue inhibitors of metalloproteinases 1 and 2 (TIMP-1 and TIMP-2) are important regulators of extracellular matrix remodeling and also possess growth factor activity. The objective of these studies was to characterize TIMP-1 and TIMP-2 mRNA expression by bovine periovulatory follicles/corpora hemorrhagica (Experiment 1) and luteal tissue (Experiment 2). In Experiment 1, beef heifers (n = 27) were ovariectomized at −16 (n = 6), 0 (n = 5), 8 (n = 3), 16 (n = 4), 24 (n = 4), or 48 (n = 5) hr relative to a gonadotropin-releasing hormone induced gonadotropin surge (40 hr after prostaglandin F_2α-induced luteolysis). Total cellular RNA was isolated from the large steroidogenically active follicle or corpus hemorrhagicum obtained from each animal, and the expression of TIMP-1 and TIMP-2 mRNA was subsequently examined by northern and dot blot analysis. The expression of TIMP-1 or TIMP-2 mRNA did not differ in preovulatory follicles collected at −16 vs. 0 hr. Concentrations of both TIMP-1 and TIMP-2 mRNA (picograms per microgram of tissue DNA) were increased (P < 0.05) at 8 hr postgonadotropin surge, had declined to presurge levels by 24 hr (P < 0.05), and were increased (P < 0.05) in corpora hemorrhagica collected at 48 hr after a gonadotropin surge. In Experiment 2, corpora lutea were collected from beef heifers on Days 4, 10, 15 (n = 4 each), or 19 (n = 3) postestrus (Day 0 = estrus). Concentrations of TIMP-1 mRNA (picograms per microgram of tissue DNA) were greater in corpora lutea collected on Day 4 (P < 0.05) vs. Day 10, 15, or 19. Concentrations of TIMP-2 mRNA increased (P < 0.05) from Day 4 to 15 and decreased (P < 0.05) by Day 19. We conclude that: 1) during the periovulatory period, the ontogenies of TIMP-1 and TIMP-2 mRNA expression are similar, whereas 2) during luteal phase, TIMP-1 mRNA expression is maximal during the early luteal phase, whereas concentrations of TIMP-2 mRNA peak during the midluteal phase. TIMP-1 and TIMP-2 may play important roles in the regulation of extracellular matrix remodeling during the periovulatory period and the subsequent luteal phase.     

Blood LH level and induced ovulation after hCG and PMSG treatment in ovarian quiescent cattle

Ovarian quiescent cattle bearing follicle with palpable size were treated with single intramuscular injection of 750-6,000 IU of human chorionic gonadotrophin (hCG) in 13 cases and 1,000-2,000 IU of pregnant mare serum gonadotrophin (PMSG) in 5 cases. Changes of blood luteinizing hormone (LH) level, estrus and ovulation after the treatments were examined. After the hCG treatment LH level became slightly high from 0.2-0.6 ng/ml of pre-treatment to 0.3-1.9 ng/ml of post-treatment and maintained the level up to ovulation without the ovulatory LH surge. Ovulation was induced about 36 hr after the treatment in 12 cases. The ovulations were all silent ovulations. After the PMSG treatment LH level became slightly high from 0.6 ng/ml of pre-treatment to 1.3 ng/ml of post-treatment and the level lasted until the ovulatory LH surge. The ovulatory LH surge occurred about 39 hr after the PMSG treatment in 4 cases with a peak of about 32 ng/ml. Ovulation was induced about 74 hr after the treatment in all 5 cases. Four cases showed estrus but one in which the LH surge could not be confirmed did silent estrus preceding the induced ovulations. It was demonstrated that hCG induced ovulation without the LH surge but PMSG induced the ovulatory LH surge and the subsequent ovulation in ovarian quiescent cattle.     

Pharmacokinetics and tissue residues of enrofloxacin in the largemouth bass (Micropterus salmoides) after oral administration

The study was carried out to evaluate the pharmacokinetic disposition of enrofloxacin (ENF) with a single dose of 20 mg/kg after oral administration in largemouth bass (Micropterus salmoides) at 28°C. The concentrations of ENF and of its metabolite ciprofloxacin (CIP) in plasma, liver, and muscle plus skin in natural proportions were determined using HPLC. The concentration–time data for ENF in plasma were best described by a two-compartment open model. After oral administration, the maximum ENF concentration (C_max) of 10.99 μg/ml was obtained at 0.60 hr. The absorption half-life (T_1/2Ka) of ENF was calculated to be 0.07 hr whereas the elimination half-life (T_1/2β) of the drug was 90.79 hr. The estimates of area under the plasma concentration–time curve (AUC) and apparent volume of distribution (Vd/F) were 1,185.73 μg hr/ml and 2.21 L/kg, respectively. ENF residues were slowly depleted from the liver and muscle plus skin of largemouth bass with the T_1/2β of 124.73 and 115.14 hr, respectively. Very low levels of ciprofloxacin were detected in the plasma and tissues. A withdrawal time of 24 days was necessary to ensure that the residues of ENF + CIP in muscle plus skin were less than the maximal residue limit (MRL) of 100 μg/kg established by the European Union.     

Pharmacokinetics of cefquinome in crucian carp (Carassius auratus gibelio) after oral,intramuscular, intraperitoneal,and bath administration

The pharmacokinetics (PK) of cefquinome (CEQ) was studied in crucian carp (Carassius auratus gibelio) after single oral, intramuscular (i.m.), and intraperitoneal (i.p.) administration at a dose of 10 mg/kg body weight and following incubation in a 5 mg/L bath for 5 hr at 25°C. The plasma concentration of CEQ was determined using high‐performance liquid chromatography (HPLC). PK parameters were calculated based on mean CEQ concentration using WinNonlin 6.1 software. The disposition of CEQ following oral, i.m., or i.p. administration was best described by a two‐compartment open model with first‐order absorption. After oral, i.m., and i.p. administration, the maximum plasma concentration (C_max) values were 1.52, 40.53, and 67.87 μg/ml obtained at 0.25, 0.23, and 0.35 hr, respectively, while the elimination half‐life (T_1/2β) values were 4.68, 7.39, and 6.88 hr, respectively; the area under the concentration–time curve (AUC) values were 8.61, 339.11, and 495.06 μg hr/ml, respectively. No CEQ was detected in the plasma after bath incubation. Therapeutic blood concentrations of CEQ can be achieved in the crucian carp following i.m. and i.p. administration at a dosage of 10 mg/kg once every 2 days.     

Expression pattern of HIF1alpha and vasohibins during follicle maturation and corpus luteum function in the bovine ovary

The aim of this study was to characterize expression patterns of hypoxia‐inducible factor‐1alpha (HIF1A) and vasohibin family members (VASH1 and VASH2) during different stages of ovarian function in cow. Experiment 1: Antral follicle classification occurred by follicle size and estradiol‐17beta (E2) concentration in the follicular fluid into 5 groups (<0.5, 0.5–5, 5–40, 40–180 and >180 E2 ng/ml). Experiment 2: Corpora lutea (CL) were assigned to the following stages: days 1–2, 3–4, 5–7, 8–12, 13–16 and >18 (after regression) of oestrous cycle and of pregnancy (months 1–2, 3–4, 6–7, >8). Experiment 3: Cows on days 8–12 were injected with a prostaglandin F2alpha (PGF) analogue and CL were collected before and 0.5, 2, 4, 12, 24, 48 and 64 hr after PGF injection. Expression of mRNA was measured by qPCR, steroid hormone concentration by EIA and localization by immunohistochemistry. HIF1A mRNA expression in our study increases significantly in follicles during final maturation. The highest HIF1A mRNA expression was detected during the early luteal phase, followed by a significant decrease afterwards. In contrast, the mRNA of vasohibins in small follicle was high, followed by a continuous and significant downregulation in preovulatory follicles. The obtained results show a remarkable inverse expression and localization pattern of HIF1A and vasohibins during different stages of ovarian function in cow. These results lead to the assumption that the examined factors are involved in the local mechanisms regulating angiogenesis and that the interactions between proangiogenic (HIF1A) and antiangiogenic (vasohibins) factors impact all stages of bovine ovary function.     

Elicitation of release of luteinizing hormone by N-methyl-d,l-aspartic acid during three paradigms of suppressed secretion of luteinizing hormone in the female pig.

Two experiments were conducted to determine the minimal effective dose during lactation and site of action of N-methyl-d,l-aspartic acid (NMA) for elicitation of release of luteinizing hormone (LH) in female pigs. In the first experiment, three doses of NMA were given to lactating primiparous sows in which endogenous LH was suppressed by suckling of litters. In the second experiment, ovariectomized gilts were pretreated with estradiol benzoate or porcine antisera against GnRH to suppress LH and then given NMA to determine if it elicited secretion of LH directly at the anterior pituitary or through release of GnRH. In experiment 1, 3 lactating sows (17 +/- 1.5 d postpartum) were each given three doses of NMA (1.5, 3.0 and 5.0 mg/kg body weight [BW]; IV) on 3 consecutive days in a Latin Square design. Blood samples were collected every 10 min from -1 to 1 hr from injection of NMA. NMA at 1.5 and 3.0 mg/kg did not affect (p greater than .5) secretion of LH; however, 5 mg NMA/kg elicited a 114% increase (p less than .001) in circulating levels of LH during 1 hr after treatment. In experiment 2, 8 ovariectomized gilts were given either estradiol benzoate (EB; 10 micrograms/kg BW; IM n = 4) to suppress release of GnRH or porcine antiserum against GnRH (GnRH-Ab; titer 1:8,000; 1 ml/kg BW; IV; n = 4) to neutralize endogenous GnRH. Gilts infused with GnRH-Ab were given a second dose of antiserum 24 hr after the first. Gilts were then given NMA (10 mg/kg BW; IV) 33 hr after EB or initial GnRH-Ab. Blood samples were drawn every 6 hr from -12 to 24 hr from EB or GnRH-Ab treatments, and every 10 min from -2 to 2 hr from NMA. Serum LH declined (p less than .001) after EB (from 1.87 +/- .2 ng/ml at 12 hr before EB to 0.46 +/- .02 ng/ml during 24 hr after EB) and GnRH-Ab (from 1.97 +/- .1 to 0.59 +/- .02 ng/ml). In gilts treated with EB, the area under the curve (AUC) for the LH response (ng.ml-1.min) 1 hr after NMA (38.7 +/- 3) was significantly greater (p less than .01) than the 1 hr prior to NMA (21.3 +/- 1.5). Treatment with NMA had no effect (p greater than .5) on secretion of LH in gilts infused with GnRH-Ab.(ABSTRACT TRUNCATED AT 400 WORDS)