30 Bull sperm kinetics after semen cryopreservation in extender containing propagermanium

There is a negative association between a plentiful production of oxygen reactive species and spermatozoa kinetics parameters. Thus, antioxidants have been added to the freezing medium to improve sperm quality due to their protective effect against membrane lipid peroxidation. Propagermanium (GE132) is an organometallic compound that has never been used in freezing medium despite its known antioxidant effect as a free radical scavenger. This study aimed to investigate the effects of different concentrations of GE132 added in a commercial freezing medium (CFM) on frozen-thawed sperm motion. Nine ejaculates of 3 Nellore bulls (3 replicates), collected by an artificial vagina, were evaluated, pooled, and divided into groups D (semen was diluted and kept at 33°C for 30min before cooling) and C (semen was cooled immediately after dilution). Both groups were submitted to the same experimental treatment, as follows: addition of 0, 500, and 1000µg mL−1 of GE132 in a CFM resulting in subgroups D0, D500, D1000, C0, C500, and C1000. The sperm samples were diluted to a final concentration of 30×106 spermatozoa per straw (0.25mL) and then cooled at 4°C for 5h before freezing. Sperm samples were assessed using a computer assisted sperm analyser at 5 and 60min post-thawing for total motility (TM;%), progressive motility (%), curvilinear velocity (μm s−1), velocity straight line (μm s−1), velocity average path (μm s−1), amplitude of the lateral head displacement (ALH; μm), beat cross frequency (Hz), linearity (LIN;%), and straightness (STR;%). Data were analysed using the R software package version 3.4.4 (2018; https://www.r-project.org/). An ANOVA was applied to assess statistical differences, and Tukey’s test was used to determine differences among subgroups. A significance level of P<0.05 was adopted. No significant differences (P>0.05) were observed among subgroups for all sperm parameters except for TM, in which C0 presented higher (P<0.05) value (68.72±3.36) than D0 (54.67±5.59), D5 (57.10±2.34), and C10 (54.20±2.73), with similar results between D10 (59.5±4.22) and C5 (59.52±4.64). There were significant differences within subgroups when comparing 5 and 60min post-thawing for TM, ALH, LIN, and STR. Total motility decreased 17.2 and 9.9% in C5 and C10, respectively. Similarly, values of ALH decreased 0.2, 0.4, and 0.2µm in D0, D5, and C5, respectively. However, the increase in LIN was 11% in D10, whereas the values for STR increased in D10 (10%), C5 (6.3%), and C10 (7.3%). The addition of GE132 to the CFM did not enhance all the sperm parameters after cryopreservation except for a slight improvement in ALH, LIN, and STR over time and TM among groups. The lack of additive effect could be due to the presence of antioxidants in the CFM; therefore, further investigation with fluorescent probes using flow cytometry and free-antioxidants freezing medium could lead to a new approach for bull sperm freezing. We acknowledge Tairana AI Station, Master Fertility, and Botupharma, Brazil.

Effects of cytochalasin E on Paracoccidioides brasiliensis

AIMS

To determine the effects of cytochalasin E, isolated from the extremophile fungus Aspergillus felis, on the cells of Paracoccidioides brasiliensis Pb18.

METHODS AND RESULTS

Cytochalasin E showed a minimal inhibitory concentration of 3·6 μmol l^-1 and minimum fungicidal concentration of 7·2 μmol l^-1 on P. brasiliensis by in vitro microdilution and IC₅₀ >964·0 μmol l^-1 on murine macrophages. Its selectivity index (>263) indicated that this compound has selectivity for fungal cells. Morphological alterations were determined by optical and fluorescence microscopy, as well as scanning and transmission electron microscopy. Cytochalasin E affected P. brasiliensis bud-forming pseudohyphae, cell morphology, cell walls and cell membranes; caused the release of cellular material; and resulted in the production of reactive oxygen species. In murine macrophages, it affected cytoskeletal actin and inhibited phagocytosis.

CONCLUSION

Cytochalasin E may be useful as an antifungal prototype against P. brasiliensis and in studies on phagocytosis.

SIGNIFICANCE AND IMPACT OF THE STUDY

Paracoccidioides spp. are the etiological agents of paracoccidioidomycosis (PCM). Treatment is prolonged to control the clinical manifestations and prevent relapse. The study on the effects of cytochalasin E in P. brasiliensis is important because it can be used as a prototype for new antifungal drugs and consequently, broadens the treatment options for PCM.

10 Evaluation of Frozen Sperm Quality After Single Layer Centrifugation with Percoll Plus® of Fresh Bull Semen

The single layer centrifugation (SLC) with Percoll Plus® (PP; GE Healthcare, Uppsala, Sweden) before freezing is not a common technique used for selection of spermatozoa in bovine. Thus, this study aimed to verify the effect of SLC with PP before freezing on integrity of plasma and acrosome membranes (IPAM), phospholipid translocation (PT), and mitochondrial membrane potential (MMP) of frozen–thawed bull sperm. Three Nellore bulls housed at the Tairana Artificial Insemination Station were used. The ejaculates (6/bull) were collected by artificial vagina and assessed for sperm motility, concentration, and morphology. Then, the sperm were pooled and ~1 billion spermatozoa, either diluted [D; 1:2 (v/v)] in freezing extender (FE; tris, fructose, citric acid, egg yolk and antibiotics, without glycerol) or undiluted (UN), were placed on top of a 9-mL column of PP (in 15-mL centrifuge tubes) at concentrations of 70% or 90%, to form the 70D, 70UD, 90D, and 90UD treatment groups. After centrifugation at 839 × g for 13 min, except for the control (C), the supernatant was discarded and the pellet diluted in FE (plus glycerol) to a final concentration of 50 × 106 spermatozoa mL−1. Afterward, 0.5-mL straws were filled, cooled for 5 h at 4°C, and frozen in a programmable freezer (Digitcool, IMV, L’Aigle, France) following the temperature/time curve: from 4°C to –10°C (5°C min−1), –10°C to –100°C (40°C min−1) and from –100°C to –140°C (20°C min−1), in a total of 8 min, when the straws were plunged into and stored in liquid nitrogen until evaluation. Thawed sperm (at 37°C/30 s) was diluted at 5 × 106 spermatozoa mL−1 in TALP-polyvinyl alcohol (PVA) plus Hoechst 342 (100 μg mL−1; Sigma Co., St. Louis, MO, USA). After that, samples were stained for membrane integrity with the association of fluorescent probes propidium iodide (PI, 50 μg mL−1; Sigma Co.), fluorescein thiocyanate (FITC)-Pisum sativum agglutinin (PSA, 1 mg mL−1; Sigma Co.) and Annexin V-APC (BD Pharmingen, Franklin Lakes, NJ, USA), and with MitoStatus Red (20 nM; BD Pharmingen) and YO-PRO-1 (7.5 μM; Molecular Probes Inc., Eugene, OR, USA) for MMP. Sperm samples were analysed by flow cytometer (BD LSR; Fortessa, Becton Dickinson, Mountain View, CA, USA) and the results expressed as percentage of intact cells or qualitative fluorescence expressed in arbitrary units (AU). Analysis of variance and Tukey’s test were used for statistical analysis with P < 0.05 taken as significant. There were no differences between groups for IPAM (values ranging from 45.9 ± 7.0% to 55.6 ± 8.5%). Similarly, results of PT translocation did not differ among the groups (range from 34.7 ± 7.0% to 47.6 ± 7.0%). However, there was a tendency of increasing MMP (P = 0.10) in 70UD (1789 ± 258 UA), 70D (1776 ± 162.1 UA), and 90UD (1757 ± 133.8 UA) compared with C (1368 ± 267.4 UA) and 90D (1356 ± 145 UA). In conclusion, SLC did not compromise sperm membrane functionality and it seemed to select spermatozoa with higher mitochondrial functional activity when centrifuged at the concentration of 70% and 90D. This research was funded by FAPESP # 2015/20986-3, Tairana Artificial Insemination Station, MasterFertility Ltda, Brazil.

9 Single Layer Centrifugation of Bull Semen Through Percoll Plus® Before Cryopreservation

We previously reported that single layer centrifugation (SLC) with Percoll® (GE Healthcare, Uppsala, Sweden) of fresh bovine semen resulted in improved sperm progressive motility and movement, as evidenced by computer-assisted sperm analyzer (CASA) after freezing-thawing. However, no report has been found in the literature on the use of Percoll Plus® (PP; GE Healthcare), a nontoxic colloid, for the same purpose. Thus, this study aimed to verify the effects of SLC-PP before bull sperm freezing on sperm kinematics after cryopreservation. Ejaculates were collected from 3 Nellore bulls (6 from each) using an artificial vagina. After collection, the semen was assessed and pooled, and then 1 billion spermatozoa either diluted [D; 1:2 (v/v)] in freezing extender (FE, without glycerol) or undiluted (UD) was layered on top of a 9-mL column of PP (in 15-mL centrifuge tubes) at concentrations of 70% or 90% to form the 70D, 70UD, 90D, and 90UD treatment groups. Following centrifugation for 13 min at 839 × g [except for the control (C) group], the supernatant was removed and the sperm pellet diluted to 50 × 106 sperm mL−1 in FE medium plus glycerol. Then, frozen–thawed sperm samples were analysed by CASA (MMC Sperm, St. Petersburg, Russia) for the following parameters: total motility (TM, %), progressive motility (PM, %), curvilinear velocity (VCL, µm−1), straight line velocity (VSL, µm s−1), average path velocity (VAP, µm s−1), amplitude of lateral head displacement (ALH, µm), beat cross frequency (BCF, Hz), linearity (LIN, %), and straightness (STR, %). For statistical analyses, ANOVA and Student-Newman-Keuls test were used. Data are presented as mean ± SEM with P < 0.05 taken as significant. No difference was found among the groups for TM, VSL, BCF, and STR. However, the percentage of PM was higher (P < 0.05) in the SLC-selected sperm samples (values ranging from 42.0 ± 7.0 to 47.4 ± 11.4) than in C (28.8 ± 5.0), and ALH was lower in 70UD (1.6 ± 0.12) and 70D (1.7 ± 0.10) than in C (1.9 ± 0.2). Moreover, 70UD (49.0 ± 1.0), 90UD (50.0 ± 3.0), and 90D (50.0 ± 4.0) displayed higher percentage of LIN (P < 0.05) compared with C (45.0 ± 2.0) and 70D (48.0 ± 3.0). On the other hand, similar results were obtained for VCL (from 126.3 ± 8.0 to 130.0 ± 20.5) and VAP (from 82.7 ± 14.5 to 85.1 ± 6.9) in C, 70UD, and 70D, but these values differed (P < 0.05) from those for VCL in 90UD (104.6 ± 10.3) and 90D (97.2 ± 22.0) as well as for VAP in 90UD (72.2 ± 11.0) and 90D (71.8 ± 9.6). These are the first data demonstrating favourable influences of SLC with 70% Percoll Plus® to select distinct sperm subpopulations as evidenced by enhanced PM, LIN, and ALH. Thus, SLC-PP could optimize the production of frozen bull semen by decreasing the number of sperm per insemination dose, and help to circumvent limitations associated with the poor semen quality sometimes found in bulls of high genetic merit. This research was funded by FAPESP # 2015/20986-3, MasterFertility and Tairana Artificial Insemination Station, Brazil.

8 Effect of Single Layer Centrifugation with Percoll Plus® of Fresh Bull Semen on Plasma Membrane Stability and Lipid Peroxidation After Cryopreservation

The discontinuous density gradient with Percoll® is routinely used for sperm selection before IVF in bovine in vitro embryo production. However, few studies have been addressed to investigate the use of this colloid in single layer centrifugation (SLC) before sperm freezing. Therefore, this study aimed to verify the effect of SLC with Percoll Plus® (PP; GE Healthcare, Uppsala, Sweden) before freezing on plasma membrane stability (PMS) and lipid peroxidation (LP) of frozen–thawed bull semen. Three Nellore bulls housed at the Artificial Insemination Station were used. The ejaculates, 6 of each bull, were collected by artificial vagina. On the day of each collection, semen was first assessed for sperm motility, concentration, and morphology. Then, the ejaculates were pooled and ~1 billion spermatozoa either diluted [D; 1:2 (v/v)] in freezing extender (without glycerol) or undiluted (UN) was placed on top of a 9-mL column of PP at concentrations of 70% or 90%, resulting in the 70D, 70UD, 90D, and 90UD treatment groups. After centrifugation at 839 × g for 13 min, except for the control group, the supernatant was removed and the pellet of spermatozoa was resuspended in freezing extender (plus glycerol) to a final concentration of 50 × 106 spermatozoa mL−1. Then, 0.5-mL straws were filled, cooled, and frozen. Sperm samples of each group and different days of collection were thawed in a water bath at 37°C for 30 s and diluted at 5 × 106 spermatozoa mL−1 in TALP-polyvinyl alcohol (PVA) plus Hoechst 342 (Sigma Co., St. Louis, MO, USA). Then, samples were stained for PMS with the association of MitoSoxRed (Molecular Probes Inc., Eugene, OR, USA) and YO-PRO-1 (Thermo Fisher Scientific, Hampton, NH, USA) and with C11-BODYPY (Thermo Fisher Scientific) for LP. The sperm samples were analysed by flow cytometer (BD LSR, Fortessa, Becton Dickinson, Mountain View, CA, USA), with the data analysed through use of BD FACSDIVATM software (version 6.1). Analysis of variance and Tukey’s test were used for statistical analysis with P < 0.05 taken as significant. A lower percentage of cells displaying no destabilised membrane was found in 70D (27.6 ± 5.6) compared with the control group (43.1 ± 3.0), but no difference was observed among control group, 70UD (37.2 ± 5.1), 90UD (42.2 ± 7.5), and 90D (32.3 ± 6.5). There was a tendency (P = 0.08) for a higher proportion (P < 0.05) of cells showing LP in control group (48.2 ± 5.7), 70D (48.3 ± 8.5), and 90D (44.43 ± 7.3) compared with the undiluted groups. Thus, spermatozoa selection using SLC with Percoll Plus® did not enhance membrane stability, but sperm LP might be diminished by using SLC with lesser dilution or concentration. It is suggested that lower generation of reactive oxygen species occurred when SLC with PP was used, indicating a possible protective effect on membrane phospholipids. Further studies, including anion superoxide, hydrogen peroxide, and mitochondrial membrane potential could elucidate these findings. This research was supported by FAPESP (grant #2015/20986-3), Tairana AI Station and Master Fertility, Brazil.

Protective effects of the angiotensin type 1 receptor antagonist losartan in infection-induced and arthritis-associated alveolar bone loss

BACKGROUND AND OBJECTIVE

The angiotensin type 1 (AT1) receptor has been implicated in the pathogenesis of inflammatory bone disorders. This study aimed to investigate the effect of an AT1 receptor antagonist in infection-induced and arthritis-associated alveolar bone loss in mice.

MATERIAL AND METHODS

Mice were subjected to Aggregatibacter actinomycetemcomitans oral infection or antigen-induced arthritis and treated daily with 10 mg/kg of the prototype AT1 antagonist, losartan. Treatment was conducted for 30 d in the infectious condition and for 17 d and 11 d in the preventive or therapeutic regimens in the arthritic model, respectively. The mice were then killed, and the maxillae, serum and knee joints were collected for histomorphometric and immunoenzymatic assays. In vitro osteoclast assays were performed using RAW 264.7 cells stimulated with A. actinomycetemcomitans lipopolysacharide (LPS).

RESULTS

Arthritis and A. actinomycetemcomitans infection triggered significant alveolar bone loss in mice and increased the levels of myeloperoxidase and of TRAP(+) osteoclasts in periodontal tissues. Losartan abolished such a phenotype, as well as the arthritis joint inflammation. Both arthritis and A. actinomycetemcomitans conditions were associated with the release of tumor necrosis factor alpha (TNF-α), interferon-gamma, interleukin-17 and chemokine (C-X-C motif) ligand 1 and an increased RANKL/osteoprotegerin ratio in periodontal tissues, but such expression decreased after losartan treatment, except for TNF-α. The therapeutic approach was as beneficial as the preventive one. In vitro, losartan prevented LPS-induced osteoclast differentiation and activity.

CONCLUSION

The blockade of AT1 receptor exerts anti-inflammatory and anti-osteoclastic effects, thus protecting periodontal tissues in distinct pathophysiological conditions of alveolar bone loss.

The relevance of leukotrienes for bone resorption induced by mechanical loading

5-Lipoxygenase (5-LO) metabolites are important pro-inflammatory lipid mediators. However, much still remains to be understood about the role of such mediators in bone remodeling. This study aimed to investigate the effect of 5-LO metabolites, LTB4 and CysLTs, in a model of mechanical loading-induced bone remodeling. Strain-induced tooth movement and consequently alveolar bone resorption/apposition was achieved by using a coil spring placed on molar and attached to incisors of C57BL6 (wild-type-WT), 5-LO deficient mice (5-LO(-/-)) and mice treated with 5-LO inhibitor (zileuton-ZN) or with antagonist of CysLTs receptor (montelukast-MT). The amount of bone resorption and the number of osteoclasts were determined morphometrically. The expression of inflammatory and bone remodeling markers in periodontium was analyzed by qPCR. Osteoclast differentiation and TNF-α production were evaluated in vitro using RAW 264.7 cells treated with LTB4 or LTD4. Bone resorption, TRAP(+) cells and expression of Tnfa, Il10 and Runx2 were significantly diminished in 5-LO(-/-), ZN- and MT-treated mice. The expression of Rank was also reduced in 5-LO(-/-) and MT-treated mice. Accordingly, LTB4 and LTD4 in association with RANKL promoted osteoclast differentiation and increased TNF-α release in vitro. These data demonstrate that the absence of 5-LO metabolites, LTB4 and CysLTs reduces osteoclast recruitment and differentiation, consequently diminishing bone resorption induced by mechanical loading. Thus, 5-LO might be a potential target for controlling bone resorption in physiological and pathological conditions.

14 CONCEPTION RATE OF BUFFALO HEIFERS TREATED WITH OESTRADIOL CYPIONATE TO INDUCE OVULATION IN TIMED ARTIFICIAL INSEMINATION PROGRAMS

Reducing animal handling and costs in timed artificial insemination (TAI) systems are of great interest in animal production, regardless of the species. Thus, this study was carried out to investigate the effects of administering oestradiol cypionate (EC) or hCG to induce ovulation in buffalo (Bubalus bubalis) in TAI programs. The 79 Bufalipso heifers housed at Institute of Animal Science, San José de las Lajas, Cuba, were, on average, 24 months of age with a body weight of 310 to 380 kg at the beginning of the experiment. The investigation was conducted out of the breeding season (25 June through 28 July 2012). Heifers were randomly assigned to 1 of 3 treatment groups; either hCG (control group) or EC1 and EC2, in which TAI was performed at either 48 or 56 h after the EC injection, respectively. On the first day of the treatment regime (Day 0), animals received oestradiol benzoate (2 mg i.m.; Sincrodiol®, Ourofino, Brazil), followed by the insertion of an intravaginal device containing 1 g of progesterone (Primer®, Tecnopec, São Paolo, Brazil). On Day 9, an intramuscular luteolytic dose of cloprostenol (500 μg; Ciosin®, Intervet, Brazil) and eCG (500 UI; Novormon®, Intervet) were given in all heifers along with the removal of the intravaginal device. On the same day, 0.5 mg of EC (ECP®, Pfizer, Brazil) was administered intramuscularly in the EC1and EC2 groups. Animals in the hCG group received hCG (1000 IU i.m.; Vetecor®, Hertape Calier, Spain) on Day 11 and were inseminated 14 h later. Pregnancy diagnosis was performed by ultrasound 35 days after TAI. Data were analysed by a chi-squared test, with P < 0.05 taken as significant. There were no differences among treatment groups, with values of 57.7 (15/26), 60.7 (17/28), and 64% (16/25) for the EC1, EC2, and hCG groups, respectively. In conclusion, oestradiol cypionate was effective at inducing ovulation in buffalo heifers in TAI programs comparable to the control group, as evidenced by the conception rates. In addition, animals subjected to the EC protocol pass just 3 times through the corral instead of 4 when receiving hCG, which decreases the animal handling and costs.

MyD88 is essential for alveolar bone loss induced by Aggregatibacter actinomycetemcomitans lipopolysaccharide in mice

Aggregatibacter actinomycetemcomitans is a Gram-negative bacteria highly associated with localized aggressive periodontitis. The recognition of microbial factors, such as lipopolysaccharide from A. actinomycetemcomitans ((Aa)LPS), in the oral environment is made mainly by surface receptors known as Toll-like receptors (TLR). TLR4 is the major LPS receptor. This interaction leads to the production of inflammatory cytokines by myeloid differentiation primary-response protein 88 (MyD88) -dependent and -independent pathways, which may involve the adaptor Toll/interleukin-1 receptor-domain-containing adaptor inducing interferon-β (TRIF). The aim of this study was to assess the involvement of MyD88 in alveolar bone loss induced by (Aa)LPS in mice. C57BL6/J wild-type (WT) mice, MyD88, TRIF or TRIF/MyD88 knockout mice received 10 injections of Aa LPS strain FDC Y4 (5 μg in 3 μl), in the palatal gingival tissue of the right first molar, every 48 h. Phosphate-buffered saline was injected in the opposite side and used as control. Animals were sacrificed 24 h after the 10th injection and the maxillae were removed for macroscopic and biochemical analyses. The injections of Aa LPS induced significant alveolar bone loss in WT mice. In the absence of MyD88 or TRIF/MyD88 no bone loss induced by (Aa)LPS was observed. In contrast, responses in TRIF(-/-) mice were similar to those in WT mice. Diminished bone loss in the absence of MyD88 was associated with fewer TRAP-positive cells and increased expression of osteoblast markers, RUNX2 and osteopontin. There was also reduced tumor necrosis factor-α production in MyD88(-/-) mice. There was less osteoclast differentiation of hematopoietic bone marrow cells from MyD88(-/-) mice after (Aa)LPS stimulation. Hence, the signaling through MyD88 is pivotal for (Aa)LPS-induced osteoclast formation and alveolar bone loss.

164 INFLUENCE OF LINEAGE OF OOCYTE DONOR ON THE YIELD AND MORPHOLOGY OF OOCYTES RECOVERED BY ULTRASOUND-GUIDED FOLLICULAR ASPIRATION IN NELLORE COWS

Several factors exert considerable influence on oocyte production and quality, such as donor age, nutrition, season and others. However, very few studies have been done to verify the effects of breed on the quantity or quality of oocytes, or both. In Brazil, the Nellore breed has been developed as a result of many years of selective breeding from 6 major ancestor bulls imported from India in the 1960s. These animals have characterised their respective lineages, as evidenced by the well-defined genetic traits. This study was carried out to investigate the influence of the genetic lineage of oocyte donors on the number and quality of oocytes obtained through ultrasound-guided follicular aspiration in Nellore cows derived from 2 lineages of bulls [Karvadi (K) and Taj Mahal (T)]. Both maternal (Km and Tm) and paternal (Kp and Tp) lineages were investigated. Oocyte aspirations were repeatedly performed with an aspiration interval of 15 days without the superovulation procedure in 56 donor females over a period of 2 years. At the beginning of the experiment, the animals were on average 78 ± 12 months old with a body condition score of 3.6 ± 0.08 (on a 5-point scale). Recovered cumulus–oocyte complexes were counted, morphologically examined and classified into 7 categories (grades I to VII) according to the number of layers of the cumulus–oocyte and the appearance of the cytoplasm. Data were analysed using ANOVA and Tukey's test after transformation into log(x + 1). Values are reported as means ± s.e.m. and differences (P > 0.05) were taken as significant. The mean number of oocytes retrieved from donors of lineage Tp-Tm was higher (n = 9; 28.23 ± 1.92; P < 0.05) than that obtained for lineages Kp-Tm (n = 11; 21.34 ± 1.32), Kp-Km (n = 15; 21.28 ± 1.73) and Tp-Km (n = 21; 16.72 ± 1.31). There was no significant difference in the mean number of recovered oocytes between donors of lineages Kp-Tm and Kp-Km; however, lineage Tp-Km yielded a lower number of oocytes. Donors of lineage Kp yielded more (P < 0.05) oocytes of grade III than lineage Tp (10.11 ± 0.66 vs 8.79 ± 0.58, respectively). These lineages produced a higher mean number of oocytes graded as I, II and III (3.14 ± 0.21, 4.93 ± 0.33 and 10.11 ± 0.66 vs 3.19 ± 0.21, 5.59 ± 0.44 and 8.79 ± 0.58, respectively) than any other categories. However, more oocytes (P < 0.05) of grades I, II and III were obtained for lineage Tm (3.64 ± 0.25, 5.9 ± 0.42 and 11.67 ± 0.67) than for lineage Km (2.85 ± 0.19, 4.92 ± 0.40 and 7.73 ± 0.56, respectively), with similar results for oocytes of grades IV, V, VI and VII. In conclusion, the genetic lineage of the oocyte donor influenced the production and quality of oocytes obtained through ultrasound-guided follicular aspiration in Nellore cows. Selection of donor cows based on their oocyte morphology and availability can further improve IFV programs.

Momentary maximizing in concurrent schedules with a minimum interchangeover interval

Eight pigeons were trained on concurrent variable-interval variable-interval schedules with a minimum interchangeover time programmed as a consequence of changeovers. In Experiment 1 the reinforcement schedules remained constant while the minimum interchangeover time varied from 0 to 200 s. Relative response rates and relative time deviated from relative reinforcement rates toward indifference with long minimum interchangeover times. In Experiment 2 different reinforcement ratios were scheduled in successive experimental conditions with the minimum interchangeover time constant at 0, 2, 10, or 120 s. The exponent of the generalized matching equation was close to 1.0 when the minimum interchangeover time was 0 s (the typical procedure for concurrent schedules without a changeover delay) and decreased as that duration was increased. The data support the momentary maximizing theory and contradict molar maximizing theories and the melioration theory.

Apoptotic mimicry: phosphatidylserine liposomes reduce inflammation through activation of peroxisome proliferator-activated receptors (PPARs) in vivo

BACKGROUND AND PURPOSE

Recently, there has been much attention paid to understanding the molecular mechanisms underlying apoptosis and the functional consequences of apoptotic body clearance by phagocytes. In an attempt to investigate this latter aspect, the present study evaluated the anti-inflammatory effects of in vivo administration of phosphatidylserine (PS) liposomes, a well-characterised membrane component expressed during apoptosis. The participation of peroxisome proliferator-activated receptors (PPARs) in PS-mediated effects was also investigated.

EXPERIMENTAL APPROACH

The anti-inflammatory effect of PS liposomes on the delayed phase of carrageenan mouse paw oedema was studied. PS liposomes were injected at different doses and times, after carrageenan. Hind paws were collected for evaluation of interleukin-1beta (IL-1beta) levels, myeloperoxidase (MPO) and N-acetyl-glucosaminidase (NAG) activities and Evans blue dye leakage. Participation of PPAR pathways was explored by using PPAR antagonists (BADGE and GW9662).

KEY RESULTS

Administration of PS, but not phosphatidylcholine (PC), liposomes (20-200 mg kg(-1), i.p., 8 h after carrageenan) reduced the paw oedema in a dose-dependent manner. PS liposomes were effective even when administered 24 and 48 h after carrageenan, a time at which indomethacin (1 mg kg(-1), i.p.) had no significant effects. Carrageenan-induced Evans blue leakage and IL-1beta production was decreased in PS-treated paws. The PPAR antagonists (BADGE and GW9662) partially prevented the anti-inflammatory effects of PS administration.

CONCLUSIONS AND IMPLICATIONS

PS liposomes have anti-inflammatory effects in vivo that are at least partly dependent on PPAR activation. Therapeutic strategies mimicking apoptosis may be useful for the treatment of inflammatory disorders.

Impaired host defense to Klebsiella pneumoniae infection in mice treated with the PDE4 inhibitor rolipram

The increase in levels of cAMP in leukocytes by selective inhibitors of PDE4 may result in reduction of inflammation, and may be useful in the treatment of pulmonary inflammatory disorders in humans. Here, we have assessed whether oral treatment with the prototype PDE4 inhibitor, rolipram, interfered with the antibacterial host response following pulmonary infection of mice with Klebsiella pneumoniae. K. pneumoniae infection induced a marked increase in the recruitment of neutrophils to the lungs and the production of proinflammatory cytokines and chemokines, including tumor necrosis factor-alpha (TNF-alpha) and keratinocyte-derived chemokine (KC), in bronchoalveolar (BAL) fluid and lung tissue. There were also detectable amounts of interleukin-10 (IL-10) and significant lethality. Treatment with rolipram (3-30 mg kg-1) was associated with earlier lethality and significant inhibition of the TNF-alpha production. This was associated with enhanced production of IL-10 in lung tissue of rolipram-treated animals. Rolipram treatment did not affect KC expression and the recruitment of neutrophils in the lung tissue. Over 70% of neutrophils that migrated into the BAL fluid following K. pneumoniae infection ingested bacteria. Treatment with rolipram inhibited the percentage of neutrophils undergoing phagocytosis of K. pneumoniae in a dose-dependent manner. Maximal inhibition (62%) occurred at doses equal to or greater than 10 mg kg-1. Thus, treatment of mice with the PDE4 inhibitor rolipram is accompanied by earlier lethality, enhanced bacterial load and decreased capacity of the responding host to produce TNF-alpha and of neutrophils to phagocytose bacteria. It will be important to investigate whether the shown ability of PDE4 inhibitors to inhibit neutrophil phagocytosis and control experimental bacterial infection will translate into an inhibition of the ability of neutrophils to deal with infectious microorganisms in the clinical setting.

Role of the platelet-activating factor (PAF) receptor during pulmonary infection with gram negative bacteria

The lipid mediator PAF plays an important role in the phagocytosis of particles, including bacteria, and consequent production of pro-inflammatory cytokines, such as TNF-alpha and IL-8. Using a PAF receptor antagonist (UK-74,505) and PAF receptor knock-out mice, we have investigated the relevance of PAF for the inflammatory changes and lethality after pulmonary infection with the gram-negative bacteria Klebsiella pneumoniae in mice. At an inoculum of 3 x 10(6) bacteria, there was marked pulmonary (bronchoalveolar lavage and lung) neutrophilia that started early (2.5 h after infection) and peaked at 48 h. All animals were dead by day 4 of infection. The chemokine KC and the pro-inflammatory cytokine TNF-alpha increased rapidly and persisted for 48 h in the lungs. Pretreatment with UK-74,505 (30 mg kg(-1) per day, p.o.) had no significant effects on the number of infiltrating neutrophils in BAL fluid or lung tissue, as assessed by histology and measuring myeloperoxidase, or on the concentrations of KC. In contrast, concentrations of TNF-alpha and the number of bacteria inside neutrophils were significantly diminished. In order to support a role for the PAF during K. pneumoniae infection, experiments were also carried out in PAFR-deficient mice. In the latter animals, lethality occurred earlier than in wild-type controls. This was associated with greater number of bacteria in lung tissue and diminished percentage of neutrophils containing bacteria in their cytoplasm. Our results suggest that PAF, acting on its receptor, plays a protective role during infection with K. pneumoniae in mice.

Effects of the PAF receptor antagonist UK74505 on local and remote reperfusion injuries following ischaemia of the superior mesenteric artery in the rat

The effects of the long lasting and potent PAF receptor antagonist UK74505 were assessed on the local and remote injuries following ischaemia and reperfusion (I/R) of the superior mesenteric artery (SMA) in rats. In a severe model of ischaemia (120 min) and reperfusion (120) injury, in addition to the local and remote increases in vascular permeability and neutrophil accumulation, there was significant tissue haemorrhage, blood neutropenia, systemic hypotension and elevated local and systemic TNF-alpha levels. Post-ischaemic treatment with the selectin blocker fucoidin (10 mg kg(-1)) prevented neutrophil accumulation in tissue and, in consequence, all the local and systemic injuries following severe I/R. Treatment with an optimal dose of UK74505 (1 mg kg(-1)) also reversed local and remote neutrophil accumulation, increases in vascular permeability and intestinal haemorrhage. UK74505 partially inhibited blood neutropenia and reperfusion-induced hypotension. Interestingly, both fucoidin and UK74505 prevented the local, but not systemic, increases of TNF-alpha levels following severe I/R injury, demonstrating an important role of migrating cells for the local production of TNF-alpha. However, the results do not support a role for PAF as an intermediate molecule in the production of systemic TNF-alpha. The beneficial effects of UK74505 and other PAF receptor antagonists in models of I/R injury in animals and the safety of UK74505 use in man warrant further investigations of the use of this drug as preventive measure for I/R injury in humans.

Effects of a BLT receptor antagonist on local and remote reperfusion injuries after transient ischemia of the superior mesenteric artery in rats

Reperfusion of ischemic vascular beds may lead to recruitment and activation of leukocytes, release of mediators of the inflammatory process and further injury to the affected vascular bed and to remote sites. Neutrophils appear to play a major role in the pathophysiology of reperfusion injury. Amongst inflammatory mediators shown to activate neutrophils and induce their recruitment in vivo, much interest has been placed on the role of leukotriene (LT)B(4). Here, we have assessed the effects of the BLT receptor antagonist (+)-1-(3S, 4R)-[3-(4-phenyl-benzyl)-4-hydroxy-chroman-7-yl]-cyclopentane carboxylic acid (CP 105,696) in a model of neutrophil-dependent ischemia and reperfusion injury in the rat. The superior mesenteric artery was isolated and ischemia was induced by its total occlusion for 30 min. After 30 min of reperfusion, injury was assessed by evaluating the extravasation of Evans blue, an index of vascular permeability, and the levels of myeloperoxidase, an index of neutrophil accumulation, in the intestine, mesentery and lung. The neutrophil-dependence of the local (intestine and mesentery) and remote (lung) injury was confirmed by using fucoidin, a selectin blocker, and WT-3, an anti-CD18 monoclonal antibody. Post-ischemic treatment with CP 105,696 dose-dependently inhibited vascular permeability and neutrophil accumulation in the intestine and mesentery. CP 105,696 also blocked the vascular permeability changes, but not neutrophil accumulation, in the lungs after reperfusion injury. Virtually identical results were obtained with another BLT receptor antagonist, 1-(5-ethyl-2-hydroxy-4-(6-methyl-6-(1H-tetrazol-5-yl)-heptoxy++ +)-phenyl )ethanone (LY255283). Our results suggest that post-ischemic treatment with BLT receptor antagonists may inhibit local and remote ischemia and reperfusion injury by blocking both the accumulation and/or activation of neutrophils.

The modulation of ecto-nucleotidase activities by glutamate in cultured cerebellar granule cells

Several enzymes hydrolyze ATP, producing ADP which is hydrolyzed to AMP. Ecto-5'-nucleotidase produces adenosine from AMP. Glutamate (Glu) is an excitatory neurotransmitter and increases extracellular adenosine levels, which is considered an important inhibitory neuromodulator. Here we show that Glu activates ADP and AMP hydrolysis. NMDA and kainic acid (KA) also increased these enzymatic activities, but 1-aminocyclopentane-1S,3R-dicarboxylic acid (ACPD) had no effect. Dihydrokainate (DHK), an inhibitor of glutamate uptake, also blocked glutamate-evoked activation of ecto-nucleotidases, suggesting that this activation was also Glu transporters dependent. Therefore, we suggest that the Glu-evoked stimulation of ecto-nucleotidases might contribute to the increase of adenosine in extracellular space induced by Glu.

Effects of tachykinin NK1 or PAF receptor blockade on the lung injury induced by scorpion venom in rats

In cases of severe human scorpion envenoming, lung injury is a common finding and frequently the cause of death. In the rat, two distinct mechanisms account for oedema following the intravenous injection of the venom -- acute left ventricular failure resulting from a massive release of catecholamines and an increase in pulmonary vascular permeability. In the present work, we investigated the effects of a tachykinin NK1 receptor antagonist (CP96,345, the dihydrochloride salt of (2S,3S)-cis-2-(diphenylmethyl)-N-((2-methoxyphenyl)methyl)-1-az abicycol[2.2.2]octan-3-amine) and its 2 R-3 R inactive enantiomer (CP96,344) on the acute lung injury induced by the i.v. injection of Tityus serrulatus venom in rats. Lung injury was assessed by evaluating the extravasation of Evans blue dye in the bronchoalveolar lavage fluid and in the lung of venom-treated and control animals. The effects of the platelet-activating factor (PAF) receptor antagonist WEB2170 (2-methyl-1-phenylimidazol[4,5c]pyridine) were evaluated for comparison. The i.v. injection of the venom induced the extravasation of Evans blue in the bronchoalveolar lavage fluid and into the left lung. Pretreament with the tachykinin NK1 receptor antagonist CP96,345, but not CP96,344, inhibited Evans blue dye extravasation in the bronchoalveolar lavage fluid and in the lung by 96% and 86%, respectively. The PAF receptor antagonist WEB2170 inhibited the increase in vascular permeability in the bronchoalveolar lavage fluid by 60% and had no effect on the extravasation to the lung parenchyma of venom-injected animals. In addition to abrogating lung injury, pretreatment of rats with CP96,345, but not CP96,344 or WEB2170, decreased by 70% the mortality induced by the venom. This is the first study to show the relevance of the tachykinin NK1 receptor in mediating lung injury and mortality in animals injected with the neurotoxic T. serrulatus venom. Blockade of the tachykinin NK1 receptor may represent an important strategy in the treatment of patients with signs of severe envenoming and clearly deserves further studies.