Development and assessment of a novel ex vivo corneal culture technique involving an agarose-based dome scaffold for use as a model of in vivo corneal wound healing in dogs and rabbits

OBJECTIVE

To develop and assess a novel ex vivo corneal culture technique involving an agarose-based dome scaffold (ABDS) for use as a model of in vivo corneal wound healing in dogs and rabbits.

SAMPLE

Corneas from clinically normal dogs (paired corneas from 8 dogs and 8 single corneas) and rabbits (21 single corneas).

PROCEDURES

8 single dog corneas (DCs), 1 DC from each pair, and 10 rabbit corneas (RCs) were wounded with an excimer laser; 1 DC from each pair and 11 RCs remained unwounded. Corneas were cultured for 21 days on ABDSs (8 pairs of DCs and all RCs) or on flat-topped scaffolds (8 single DCs). The surface area of corneal fluorescein retention was measured every 6 (DCs) or 12 (RCs) hours until full corneal epithelialization was detected. Changes in corneal clarity were evaluated at 0, 7, 14, and 21 days.

RESULTS

Median time to full epithelialization for wounded dog and rabbit corneas was 48 and 60 hours, respectively; among wounded DCs, time to full epithelization did not differ by scaffold type. After 21 days of culture on ABDSs, all DCs and RCs that epithelialized developed a circular, diffuse, cloud-like pattern of optical haze, whereas DCs cultured on flat-topped scaffolds developed a focal, crater-like region of optical haze. All corneas on the ABDSs maintained convex curvature throughout the study.

CONCLUSIONS AND CLINICAL RELEVANCE

Wounded ex vivo DCs and RCs cultured on ABDSs reliably epithelialized, formed optical haze (consistent with in vivo wound healing), and maintained convex curvature. This culture technique may be adaptable to other species.

Comparison of carpet and toothbrush techniques for the detection of Microsporum canis in cats

OBJECTIVES

The aim of this study was to evaluate the diagnostic concordance between the toothbrush and carpet techniques for the detection of Microsporum canis in cats in a field study.

METHODS

Thirty-nine Persian cats from a cattery were used. Fungal culture samples from the haircoat of each cat were collected by stroking the coat with a sterile toothbrush and a 5 × 5 cm-sized sterile carpet square (n = 78 total samples). Specimens were inoculated onto Mycosel Agar and incubated at 25°C for 21 days. Both techniques were compared using the following parameters: number of plates without fungal growth, number of plates with contaminant growth and number of plates positive for dermatophytes.

RESULTS

The feline population in the study cattery was 39. Thirty (77%) were symptomatic and nine (23%) asymptomatic. The diagnosis was made via carpet and toothbrush methods and 78 cultures were performed. On day 21, M canis was detected in all culture plates. No contaminant molds were observed.

CONCLUSIONS AND RELEVANCE

The concordance rate between the carpet and toothbrush techniques among the 78 evaluable culture plates was 100%. Both methods are equally effective for collecting material for M canis culture. Additionally, both techniques are inexpensive and easy to perform in feline clinical practice.

Culture Methods Differ on the Isolation of Salmonella Enterica Serotypes from Naturally Contaminated Swine Fecal Samples

Four culture methods (A, B, C, and D) were comparatively evaluated for their ability to isolate Salmonella enterica from pooled swine fecal samples ( n = 100). None of the methods was able to isolate Salmonella from all positive samples. The relative sensitivity of the culture methods evaluated was 82%, 94%, 95%, and 78% for methods A, B, C, and D, respectively. The comparison of sensitivities showed that methods B and C performed significantly better ( P < 0.05) than methods A and D. Although relative sensitivities of methods B and C were equal, from the 89 positive samples concomitantly detected by both, 35 (39.3%) had different serotypes (no match) isolated by each method. On the basis of the results of this study, it was concluded that culture methods differ on the isolation of S. enterica serotypes from naturally contaminated swine fecal samples. Depending on the objective(s) of investigations on the ecology and epidemiology of S. enterica in swine populations, a method or a combination of methods should be considered for more reliable results.

Comparison of bacterial culture and polymerase chain reaction (PCR) for the detection of F. tularensis subsp. holarctica in wild animals

Detection of the zoonotic pathogen Francisella tularensis subsp. holarctica (EF tularensis) in wild animals with culture techniques as well as polymerase chain reaction were compared and discussed on the basis of the investigation of 60 animals. The samples originated from 55 European brown hares (Lepus europaeus), two red foxes (Vulpes vulpes) and one each from a wild rabbit (Oryctolagus cuniculus), a European beaver (Castor fiber), and a lemur (Lemur catta). When comparing the growth of 28 F. tularensis isolates on the cysteine blood agar and the modified Martin-Lewis-agar used in this study, cultivation was successful for 26 isolates on both media, but for two isolates only on the cysteine blood agar. Out of 43 carcasses 19 tested positive in bacteriological culture and PCR. Two culture positive samples of tonsils originating from foxes could not be confirmed by PCR, although PCR was positive in 22 samples that missed growth of F. tularensis. Comparative studies on cultural detection of E. tularensis were performed on samples of 16 hares from lung, spleen, liver and gut and in one case with a peritoneal swab. In at least one of these localizations cultivation of the pathogen was successful. Detection rate was reduced to 94% (15 of 16 hares) considering only the results of the cultures of the lungs and spleens. For a sensitive and rapid detection of F. tularensis subsp. holarctica, the PCR is a suitable method thereby avoiding hazardous multiplying of the pathogen. However, cultivation of F. tularensis is often a prerequisite for further studies on antibiotic resistance patterns of the pathogen, molecular epidemiological and pathological analyses of tularaemia.

Viral replication in excised fin tissues (VREFT) corresponds with prior exposure of Pacific herring, Clupea pallasii (Valenciennes), to viral haemorrhagic septicaemia virus (VHSV)

Procedures for a viral replication in excised fin tissue (VREFT) assay were adapted to Pacific herring, Clupea pallasii, and optimized both to reduce processing time and to provide the greatest resolution between naïve herring and those previously exposed to viral haemorrhagic septicaemia virus (VHSV), Genogroup IVa. The optimized procedures included removal of the left pectoral fin from a euthanized fish, inoculation of the fin with >10(5) plaque-forming units (PFU) mL(-1) VHSV for 1 h, rinsing the fin in fresh medium six times to remove unadsorbed virions, incubation of the fin in fresh medium for 4 days and enumeration of the viral titre in a sample of the incubation medium by plaque assay. The optimized VREFT assay was effective at identifying the prior exposure history of laboratory-reared Pacific herring to VHSV. The geometric mean VREFT value was significantly greater (P < 0.01) among naïve herring (1.2 × 10(3) PFU mL(-1) ) than among groups that survived exposure to VHSV (1.0-2.9 × 10(2) PFU mL(-1) ); additionally, the proportion of cultures with no detectable virus was significantly greater (P = 0.0002) among fish that survived exposure to VHSV (39-47%) than among naïve fish (3.3%). The optimized VREFT assay demonstrates promise for identifying VHSV exposure history and forecasting disease potential in populations of wild Pacific herring.

Influence of cobalt concentration on vitamin B12 production and fermentation of mixed ruminal microorganisms grown in continuous culture flow-through fermentors

An experiment was conducted to determine the effects of dietary concentrations of Co on vitamin B12 production and fermentation of mixed ruminal microbes grown in continuous culture fermentors. Four fermentors were fed 14 g of DM/d. The DM consisted of a corn and cottonseed hull-based diet with Co supplemented as CoCO3. Dietary treatments were 1) control (containing 0.05 mg of Co/kg of DM), 2) 0.05 mg of supplemental Co/kg of DM, 3) 0.10 mg of supplemental Co/kg of DM, and 4) 1.0 mg of supplemental Co/kg of DM. After a 3-d adjustment period, fermentors were sampled over a 3-d sampling period. This process was repeated 2 additional times for a total of 3 runs. Ruminal fluid vitamin B12 concentrations were affected by Co supplementation (P < 0.01), and there was a treatment x day interaction (P < 0.01). By sampling d 3, cultures fed the basal diet supplemented with 0.10 mg of Co/kg had greater (P < 0.05) vitamin B12 concentrations than those supplemented with 0.05 mg of Co/kg of DM, and increasing supplemental Co from 0.10 to 1.0 mg/kg of DM increased (P < 0.01) ruminal fluid vitamin B12 concentration. Ruminal fluid succinate also was affected (P < 0.10) by a treatment x day interaction. Cobalt supplementation to the control diet greatly decreased (P < 0.05) succinate in ruminal cultures on sampling d 3 but not on d 1 or 2. Molar proportions of acetate, propionate, and isobutyrate, and acetate:propionate were not affected by the addition of supplemental Co to the basal diet. However, molar proportions of butyrate, valerate, and isovalerate increased (P < 0.05) in response to supplemental Co. The majority of long-chain fatty acids observed in this study were not affected by Co supplementation. However, percentages of C18:0 fatty acids in ruminal cultures tended (P < 0.10) to be greater for Co-supplemented diets relative to the control. Methane, ammonia, and pH were not greatly affected by Co supplementation. The results indicate that a total (diet plus supplemental) Co concentration of 0.10 to 0.15 mg/kg of dietary DM resulted in adequate vitamin B12 production to meet the requirements of ruminal microorganisms fed a high-concentrate diet in continuous-flow fermentors.

Cultivation of sponge larvae: settlement, survival, and growth of juveniles

The aim of this study was to culture sponge juveniles from larvae. Starting from larvae we expected to enhance the survival and growth, and to decrease the variation in these parameters during the sponge cultures. First, settlement success, morphological changes during metamorphosis, and survival of Dysidea avara, Ircinia oros, Hippospongia communis, under the same culture conditions, were compared. In a second step, we tested the effects of flow and food on survival and growth of juveniles from Dysidea avara and Crambe crambe. Finally, in a third experiment, we monitored survival and growth of juveniles of D. avara and C. crambe transplanted to the sea to compare laboratory and field results. The results altogether indicated that sponge culture from larvae is a promising method for sponge supply and that laboratory culture under controlled conditions is preferred over sea cultures in order to prevent biomass losses during these early life stages.

In vitro assay to select rainbow trout with variable resistance/susceptibility to viral haemorrhagic septicaemia virus

The merit of a candidate criterion of resistance to viral haemorrhagic septicaemia virus (VHSV) was tested with the view of producing experimental trout progeny with a predictable level of resistance. The criterion, the measure of in vitro viral replication in excised fin tissue (VREFT) was previously developed. Three experiments were performed, using both ordinary and homozygous doubled-haploid breeders. A set of 48 progeny was tested. Breeders were individually scored for repeated measures of VREFT, and the progeny were tested against VHSV (strain 07-71, serotype 1) through a waterborne challenge (5 x 10(4) pfu ml(-1) during 2 h). Analysis of repeated measures of VREFT revealed the risk of identifying 'false' resistant individuals. The highest value should be considered the most predictive of the resistance status. Survival of progeny ranged from 0 to 100% according to the group and the experiment. The survival was correlated to the mean VREFT value of the breeders in Expts 1 and 2 (R = 0.96 and 0.61 respectively), but not in Expt 3 (R = 0.36, ns) where all tested progeny were highly susceptible. Results thus indicate that viral growth in fin tissue is genetically correlated to resistance to waterborne disease and may be used to produce selected progeny, at least at the experimental scale. Possible implications of the relationship between VREFT and resistance for the study of resistance mechanisms are discussed.

A Low Oxygen Atmosphere during IVF Accelerates the Kinetic of Formation of In Vitro Produced Ovine Blastocysts

Among the factors that affect in vitro embryo development, oxygen atmosphere is considered to be of great influence. In this study, we evaluated the influence of two different oxygen atmospheres during in vitro fertilization (IVF) of ovine oocytes on their developmental capacity and quality assessed by cryotolerance. Cumulus oocyte complexes derived from ovaries of slaughtered sheep were matured in vitro and subsequently fertilized under low (5%) or high (20%) oxygen atmospheres, and cultured in SOF + aa + 0.4% BSA in 5% CO2 and 5% O2 up to blastocyst stage. The cleavage rates obtained in the fertilization system at 20% O2 were significantly higher than those obtained in the 5% O2 fertilization system (61.2% vs 50.8%; p < 0.01). The distribution of cleaved oocytes at 22, 26 and 40 h of culture intervals was not different in the low or high O2 atmosphere (31.4%, 26.4% and 42.1% vs 28.0%, 29.3% and 42.7% respectively). Blastocysts output on the 6th day post-fertilization (dpf) was significantly higher when oocytes were fertilized under 5% O2 concentration (63.04% in 5% O2 vs 47.36% in 20% O2), while on the 7th dpf the higher number of blastocysts was obtained in the 20% O2 system (35.10%.in 20% O2 vs 26.09% in 5% O2). After vitrification no differences were observed between low or high oxygen atmosphere in the viability rates of blastocysts obtained on day 6 (93.6% vs 96.5%), on day 7 (46.3% vs 41.7%) and on day 8 (11.1% vs 6.6%). After differential staining, no significant differences were observed in the total cell number and inner cell mass and trophoblastic cells ratio of blastocysts produced on 6 dpf (189.6 +/- 51.3 and 0.260 +/- 0.07 vs 223.3 +/- 45.6 and 0.277 +/- 0.09), on 7 dpf (168.3 +/- 25.1 and 0.316 +/- 0.06 vs 172.1 +/- 33,6 and 0.320 +/- 0.06) and on 8 dpf (121.2 +/- 23,8 and 0.302 +/- 0.03 vs 117.0 +/- 35.1 and 0.313 +/- 0.04) under low or high oxygen atmosphere respectively). In conclusion, our data suggest that low oxygen atmosphere during IVF affects positively the production of high quality ovine blastocysts.

Effects of Time at Suboptimal pH on Rumen Fermentation in a Dual-Flow Continuous Culture System

Ruminal pH varies considerably during the day, achieving values below 6.0 when cows consume large amounts of concentrates. Low ruminal pH has negative effects on ruminal fermentation. However, previous studies have indicated that rumen bacteria may resist short periods of low ruminal pH, and it is not clear how long this period may be before rumen microbial fermentation is negatively affected. Seven dual-flow continuous culture fermenters (1,320 mL) were used in 3 replicated periods with the same diet (97 g of dry matter/d of a 60:40 forage-to-concentrate diet, 18.3% crude protein, 35.9% neutral detergent fiber), temperature (39 degrees C), and solid (5%/h) and liquid (10%/h) dilution rates to study the effects of increasing time at suboptimal pH on rumen microbial fermentation and nutrient flow. Treatments were a constant pH of 6.4 and 6 different intervals of time during the day (4, 8, 12, 16, 20, 24 h) at suboptimal pH (5.5), with the rest of the day being at pH 6.4. Polynomial equations were derived using the Mixed procedure of SAS, and linear, quadratic and cubic terms were left in the equation if P < 0.10. True organic matter digestion decreased with increasing time at suboptimal pH and was best described by a cubic regression (TOMD = 58.5 - 2.15x + 0.16x2 -0.0037x3; R2 = 0.74). Digestion of NDF (DNDF = 55.1 - 1.00x; R2 = 0.75) and digestion of ADF (DADF = 56.2 - 1.33x; R2 = 0.78) decreased linearly with increasing time at suboptimal pH. Total VFA had a cubic response (VFA = 112.7 - 2.09x + 0.17x2 - 0.0054x3; R2 = 0.82). The proportion of acetate decreased linearly (acetate = 58.7 - 0.61x; R2 = 0.79). The propionate proportion increased (propionate = 17.6 + 2.09 x -0.044x2; R2 = 0.85) and branched-chain VFA decreased (BCVFA = 4.45 -0.51x + 0.014x2; R2 = 0.75) quadratically. The ammonia N concentration (NH3-N = 5.85 - 0.13x; R2 = 0.46) and flow (NH3-N flow = 0.18 - 0.0039x; R2 = 0.43) decreased linearly as the time at suboptimal pH increased. Crude protein degradation (CPd = 41.9 - 1.60x + 0.060x2; R2 = 0.71), efficiency of microbial protein synthesis (EMPS = 26.6 - 0.33x + 0.021x2; R2 = 0.77), microbial N flow (MN flow = 1.38 - 0.036x + 0.0015x2; R2 = 0.77), and dietary N flow (DN flow = 1.49 + 0.041x - 0.0015x2; R2 = 0.65) had a quadratic response. The flow of essential, nonessential, and most individual AA increased linearly with increasing time at suboptimal pH. The effects of pH on rumen fermentation appear to start as soon as pH drops to suboptimal pH.

Use of an insect cell culture growth medium to isolate bacteria from horses with effusive, fibrinous pericarditis: A preliminary study

Effusive, fibrinous pericarditis is an uncommon disease entity in horses. In 2001, pericarditis occurred in conjunction with an epizootic in central Kentucky that was associated with exposure to eastern tent caterpillars (ETCs). Bacterial isolation from equine pericardial fluid samples was attempted using an insect cell culture growth medium (ICCGM). Using previously cultured, stored frozen samples from four horses with fibrinous pericarditis, inoculation of 10% blood agar plates yielded no growth, whereas simultaneous inoculation of ICCGM resulted in the isolation of Proprionibacterium acnes, Staphylococcus equorum, a Streptococcus sp. and Pseudomonas rhodesiae from pericardial fluid samples. A similar or novel caterpillar-associated bacteria was not identified; however, use of an ICCGM might enhance isolation of bacteria from equine pericardial fluid.

The parthenogenetic activation of canine oocytes with Ca-EDTA by various culture periods and concentrations

In the present study, canine oocytes were exposed to various concentrations of and durations of exposure to EDTA saturated with Ca(2+) (Ca-EDTA), a cell membrane-impermeable metal ion chelator, to determine if parthenogenetic activation could be induced. When oocytes were cultured for 48 or 72 h in parthenogenetic activation medium (PAM) without Ca-EDTA (control) or PAM supplemented with 1 or 5mM Ca-EDTA, the highest rate of pronuclear formation (PN) was obtained in oocytes cultured in 1mM Ca-EDTA for 48 h (8.0%; P<0.05). There was no pronuclear formation in the control group (PAM without Ca-EDTA). Oocytes treated with 5mM Ca-EDTA for 48 h or 1mM Ca-EDTA for 72 h formed a parthenogenetic pronucleus (3.1 and 4.5, respectively). However, there was no pronuclear formation in oocytes treated with 5mM Ca-EDTA for 72 h. In summary, exposure to Ca-EDTA can induce pronuclear formation in canine oocytes.

Nitric oxide radicals in leucocytes and vaginal washes of Trichomonas vaginalis -infected symptomatic and asymptomatic women

The clinical spectrum of Trichomonas vaginalis infection varies from asymptomatic to mild, moderate or severe vaginitis. Nitric oxide and other reactive nitrogen radicals produced by immune effector cells are important cytotoxic and cytostatic mediators against several microorganisms including parasites. In the present study, inducible nitric oxide synthase (iNOS) and reactive nitrogen intermediates (RNI) were determined in leucocyte cultures (stimulated with T. vaginalis in vitro) and vaginal washes (VWs) of 22 symptomatic and 20 asymptomatic T. vaginalis-infected and 20 healthy women by immunoblotting and Griess method respectively. The iNOS protein was detected in leucocytes and VWs of all the symptomatic and asymptomatic women, but was not detected in any of the samples from healthy women. Mean iNOS protein band intensity was significantly higher in leucocytes as compared to VWs (P<0.001) of both symptomatic and asymptomatic women and was also higher in leucocytes of asymptomatic as compared to symptomatic women (P<0.05). Mean RNI concentration was also significantly higher in leucocytes (P<0.01) and VWs (P<0.05) of asymptomatic as compared to symptomatic women, and was also higher in samples of infected as compared to healthy women (P<0.001). These results suggest that reactive nitrogen radicals may have a role in limiting T. vaginalis infection in asymptomatic women.

Epidermal growth factor enhances meiotic resumption of canine oocytes in the presence of BSA

Despite many attempts to improve the in vitro maturation (IVM) of canine oocytes using various culture conditions, the efficiency of canine IVM remains very low compared with that of other domestic animals. In the present study we examined the effect of ovarian estrus stage on oocyte quality, and the effect of epidermal growth factor (EGF) in the presence and absence of macromolecules on the IVM of canine oocytes. More oocytes >or=100 microm in diameter were obtained from follicular ovaries than from ovaries at other estrus stages. After 72 h of culture, significantly more oocytes recovered from follicular ovaries than from anestrous and luteal ovaries were in germinal vesicle break down (GVBD). Bovine serum albumin (BSA) or fetal bovine serum (FBS) supplementation improved meiotic resumption as compared to polyvinyl alcohol (PVA) supplementation; however, there was no difference between the BSA and FBS supplements. The oocytes matured in North Carolina State University (NCSU) 37 medium containing 0.4% BSA and 100 ng/ml EGF showed the highest rates of development to the metaphase II (MII) stage when compared with the control treatment (P < 0.05). These results suggest that the estrous cycle of bitches influences the meiotic resumption of oocytes cultured in vitro, and EGF increases the meiotic resumption of canine oocytes in the presence of BSA in vitro.

Novel cysteine proteinase inTrypanosoma cruzimetacyclogenesis

With the aim to study proteinases released to the culture medium duringTrypanosoma cruzimetacyclogenesis, the presence of cysteine proteinases (CPs) was analysed in culture supernatants obtained throughout the differentiation induced by stimulation of epimastigotes withTriatoma infestanshindgut homogenate. In SDS-gelatin containing gels, an important endopeptidase activity with apparent molecular weight range between 97 and 116 kDa was encountered at pH 6, which was abolished by the specific cysteine proteinase inhibitor E-64 and TLCK, but not by pepstatin, 1,10 phenantroline or PMSF. This novel CP, namedTcCPmet, showed affinity to cystatin-Sepharose, denoting its thiol-proteinase character as well as to ConA-Sepharose, indicating it contains N-linked oligosaccharides. However, it presented a different elution pattern on ConA-Sepharose than cruzipain and, in addition, it was not recognized by anti-cruzipain serum, facts that strongly suggest the different nature of both CPs. Moroever, evidence is presented indicating thatTcCPmet was able to hydrolyse the same chromogenic peptides as cruzipain at optimal alkaline pH values, although with a different order of effectiveness. Our results indicate the presence of a novel CP secreted by metacyclic trypomastigotes and reinforces the important role of these enzymes in metacyclogenesis.

Strain characterization of Echinococcus granulosus protoscoleces of cattle origin using the in vitro vesicular development

The aim of this work was to characterize the strain of protoscoleces of E. granulosus of cattle origin using the in vitro vesicular development. The in vitro development of these samples was compared to samples of sheep origin determined previously by genetic analyses as common sheep strain (G1). There were similarities between sheep and cattle samples not only in the time of microcysts formation, but also in the development process. Vesiculated protoscoleces and protoscoleces with posterior bladders appeared during the first week of incubation. After 14 days of culture, a laminated layer appeared like a fine membrane in one of the extremes of the protoscoleces. In the sheep samples, microcysts were observed between 19 and 20 days. In the cattle samples, microcysts appeared between 20 and 23 days. The coincidence between the development times and physiological characteristics found in the present study may indicate that the parasites from cattle and sheep were of the same strain.

Effects of hexoses on in vitro oocyte maturation and embryo development in pigs

The objective was to determine the effects of supplementing hexoses in oocyte maturation and embryo culture medium on in vitro maturation (IVM) and in vitro fertilization (IVF) of porcine oocytes and in vitro development of in vitro produced (IVP) porcine embryos. In the first experiment, oocytes were matured in vitro in modified North Carolina State University (NCSU)-37 medium, supplemented with hexoses (glucose, fructose or galactose) at various concentrations: 0 (control), 2.5, 5.5 and 10 mM. Supplementing the maturation medium with either glucose or fructose (5.5 mM) increased the percentages of oocytes that matured to metaphase II (79.4 and 70.2%, respectively), as compared with the control group (P < 0.05). However, supplementing galactose had no effects on meiotic maturation and fertilization. In the second experiment, cleaved embryos were collected 3 days after IVF of oocytes matured in the maturation medium supplemented with 5.5 mM of glucose; they were cultured for an additional 4 days in modified NCSU-37 medium, supplemented with 5.5mM of glucose, fructose or galactose. The incidence of blastocyst formation was higher (P < 0.05) in the glucose and fructose groups (18.6 and 18.2%, respectively) than in the galactose group and non-supplemented control group (12.9 and 9.2%). Moreover, fructose supplementation increased the total cell number/blastocyst (48.0 versus 37.6) and reduced the index of DNA-fragmented nucleus in the blastocysts (7.6% versus 11.8%), as compared with glucose supplementation (P < 0.05). In conclusion, fructose was a practical alternative to glucose for supporting IVM of porcine oocytes and fructose was superior to glucose for producing high-quality porcine embryos in vitro.

Effect of the in vitro maturation medium on equine oocytes: comparison of follicular fluid and oestrous mare serum

The present study evaluated the effect of supplementing the medium used to mature equine oocytes in vitro with oestrous mare serum (EMS) or horse follicular fluid (HFF). To this end, 144 ovaries were obtained from mares aged 16-21 months and transported to the laboratory in Dulbecco's phosphate buffered saline (D-PBS) at 30 degrees C. Oocytes were harvested from the ovaries by slicing, and then selected for in vitro maturation (IVM) according to the number of cumulus cell layers and the characteristics of the cytoplasm. The selected oocytes were washed three times in TCM199 medium plus HEPES (TCM-199H) or in the same medium plus glutamine (TCM-199G), then matured in vitro in six study groups established according to the in vitro maturation (IVM) treatment to see possible interactions between HEPES and glutamine on other supplements: Ten percent EMS was added to two of these media (TCM-199H+EMS and TCM-199G+EMS) and 10% HFF was added to the media in two other groups (TCM-199H+HFF and TCM-199G+HFF). IVM was performed at 38.5 degrees C for 40 h in a controlled atmosphere (5% CO2, 95% relative humidity). The findings indicate that the presence of EMS or HFF in the TCM-199H medium gives rise to the best results in terms of the proportions of oocytes reaching maturity (37.7% and 36.8%, respectively). The values obtained with EMS and HFF were statistically similar to each other but differed from the other treatments. The media containing glutamine led to the highest proportions of degenerated oocytes.

The effect of oxygen tension on porcine embryonic development is dependent on embryo type

Reducing oxygen concentration from atmospheric levels during in vitro culture generally, but not invariably, improves embryonic development across a range of species. Since the few published reports of such an action in the pig are contradictory--perhaps a consequence of the derivation of the embryos prior to culture--a study was performed to examine the effect of O2 tension during culture on three different types of porcine embryos, namely: in vivo flushed embryos, and in vitro matured oocytes either fertilized in vitro or parthenogenetically activated. In vivo embryos (n=208) were flushed at the 2-8 cell stage. Cumulus oocyte complexes (COCs) destined for IVF or parthenogenetic activation were derived from 2 to 6 mm, post-pubertal ovarian follicles and matured for 48 h in TCM-199. Parthenogenones were generated by activating denuded oocytes (n=573) with 10 mM calcium ionophore, followed by 2 mM DMAP prior to culture. The IVF embryos (n=971) were produced by fertilizing COCs (day 0) with fresh ejaculated semen in modified tris-based medium for 6 h before cumulus removal. All embryos were cultured in BECM-3 containing 12 mg/mL fatty-acid-free BSA up to day 4, followed by BECM-3 supplemented with 10% calf serum until day 7. The gas environment for IVM/IVF was 5% CO2 in air, while that for IVC was either 5% CO2 in air or 5% O2, 5% CO2 and 90% N2. Low O2 tension increased both day 7 blastocyst rates (high versus low O2, respectively; 9.3+/-2.9%: 26/280; 23.9+/-4.2%: 71/293; P<0.001) and total cell numbers (39.3+/-2.9, n=24 versus 61.2+/-7.7, n=61; P=0.01) of parthenogenetically activated embryos. In contrast, such a treatment neither affected blastocyst rates (89.3+/-6.9 versus 87.8+/-7.5) nor cell numbers (87.4+/-4.5 versus 87.7+/-4.8) of in vivo flushed embryos. The effect of reduced O2 concentration on IVF embryos was intermediate, since only cell numbers were improved (69.8+/-3.5, range=17-204, n=49; 88.5+/-5.8, range=28-216; n=66; P<0.01), equivalent to that recorded in in vivo flushed embryos. However, blastocyst rates were unaffected (10.7+/-1.4%: 51/486; 12.9+/-2.2%: 67/485). The effect, when present, of reducing O2 concentration from 20 to 5% was beneficial for pig in vitro embryonic development. The responses are apparently dependent on firstly, the manner by which the embryonic cell cycle is activated and secondly, the derivation of the tissue prior to placement into culture, if the observed resilience of in vivo embryos is independent of treatment duration.

Effect of epidermal growth factor and insulin-like growth factor I on porcine preantral follicular growth, antrum formation, and stimulation of granulosal cell proliferation and suppression of apoptosis in vitro

The object of this study was to investigate the role of epidermal growth factor (EGF) and IGF-I in the regulation of preantral follicular growth, antrum formation, and granulosal cell proliferation/ apoptosis. Porcine preantral follicles were manually dissected and cultured for up to 8 d in Waymouth's (Exp. 1) or alpha-minimum Eagle's essential medium (Exp. 2 and 3) supplemented with 10 microg/mL of transferrin, 100 microg/mL of L-ascorbic acid, and 2 mU/mL of ovine FSH, in the presence (Exp. 1 and 3) or absence (Exp. 2) of 7.5% fetal calf serum. According to the experimental protocol, IGF-I (0, 1, 10, or 100 ng/mL; Exp. 1), or IGF-I (50 ng/mL), EGF (10 ng/mL) and EGF+IGF-I (Exp. 2 and 3) were added to the culture media. In Exp. 1, follicles exhibited a concentration-dependent response (P < 0.05) to IGF-I, with the highest rates of granulosal cell proliferation, follicular integrity, and recovery rate of cumulus cell-oocyte complexes and lowest incidence of apoptosis occurring at the highest IGF-I dose. In Exp. 2 serum-free medium, granulosal cell proliferation was low (1 to 5%), irrespective of whether EGF and/or IGF-I were present and cellular apoptosis was increased (P < 0.05) on d 4 and 8 in the EGF+IGF-I group compared with the addition of either factor alone. In Exp. 3, granulosal cell proliferation was high in all follicles cultured in serum-containing medium for the first 3 d, but fell sharply (P < 0.05) on d 4, except in media containing IGF-I. Collectively, EGF and IGF-I increased granulosal cell proliferation, decreased apoptosis, and promoted follicular antrum formation. These results may provide useful information for developing a preantral follicular culture system in which the oocytes are capable of fertilization and embryonic development.

Relationship between oxygen consumption and sex of bovine in vitro fertilized embryos

The present study was conducted to examine the relationship between the oxygen consumption rate and sex ratio of bovine in vitro fertilized embryos on each day of blastocyst formation. The quality of blastocysts collected on day 7, 8, and 9 after in vitro fertilization (IVF) were categorized as ranks A and B (excellent and good, respectively) based on microscopic observation of the morphology. The oxygen consumption rate and sex of individual blastocysts were evaluated using two novel techniques: scanning electrochemical microscopy (SECM) and loop-mediated isothermal amplification (LAMP), respectively. The oxygen consumption rates of embryos of rank A were significantly higher (p < 0.05) than those of rank B, irrespective of the day of blastocyst appearance after IVF. Neither did the proportion of male embryos of ranks A and B differ significantly from each other at any of the days examined, nor from the average proportion (53%). The oxygen consumption rate of embryos of rank B collected on day 8 was significantly higher (p < 0.05) in female embryos than in male embryos collected on the same day. However, there were no apparent differences of oxygen consumption rates at each day of blastocyst appearance between male and female embryos of rank A. These results indicate that the oxygen consumption rate of individual embryos reflects their quality but does not correlate with the sex ratio of embryos of excellent quality.

Echinococcus granulosus: first report of microcysts formation from protoscoleces of cattle origin using the in vitro vesicular culture technique

The aim of this work was the achievement of microcysts formation from protoscoleces of E. granulosus of cattle origin using the in vitro vesicular culture technique. Vesiculated protoscoleces and protoscoleces with posterior bladders appeared during the first week of incubation. After 14 days of culture, a laminated layer appeared like a fine membrane in one of the extremes of the protoscoleces. On day 20, some microcysts with a complete laminated layer were observed. By day 48, microcysts completely developed could be observed. This is the first study where microcysts formation was obtained using protoscoleces of E. granulosus of cattle origin.

Equine laminitis: glucose deprivation and MMP activation induce dermo-epidermal separation in vitro

REASONS FOR PERFORMING STUDY

Acute laminitis is characterised by hoof lamellar dermal-epidermal separation at the basement membrane (BM) zone. Hoof lamellar explants cultured in vitro can also be made to separate at the basement membrane zone and investigating how this occurs may give insight into the poorly understood pathophysiology of laminitis.

OBJECTIVES

To investigate why glucose deprivation and metalloproteinase (MMP) activation in cultured lamellar explants leads to dermo-epidermal separation.

METHODS

Explants, cultured without glucose or with the MMP activator p-amino-phenol-mercuric acetate (APMA), were subjected to tension and processed for transmission electron microscopy (TEM).

RESULTS

Without glucose, or with APMA, explants under tension separated at the dermo-epidermal junction. This in vitro separation occurred via 2 different ultrastructural processes. Lack of glucose reduced hemidesmosomes (HDs) numbers until they disappeared and the basal cell cytoskeleton collapsed. Anchoring filaments (AFs), connecting the basal cell plasmalemma to the BM, were unaffected although they failed under tension. APMA activation of constituent lamellar MMPs did not affect HDs but caused AFs to disappear, also leading to dermo-epidermal separation under tension.

CONCLUSIONS

Natural laminitis may occur in situations where glucose uptake by lamellar basal cells is compromised (e.g. equine Cushing's disease, obesity, hyperlipaemia, ischaemia and septicaemia) or when lamellar MMPs are activated (alimentary carbohydrate overload).

POTENTIAL RELEVANCE

Therapies designed to facilitate peripheral glucose uptake and inhibit lamellar MMP activation may prevent or ameliorate laminitis.

Effects of Retinol on the in vitro Development of Bos Indicus Embryos to Blastocysts in Two Different Culture Systems

The objective of this study was to evaluate the effect of retinol on the in vitro development of early embryos of cultured Bos indicus (Expt 1) to the blastocyst stage in medium simplex of optimization (KSOM) or sintetic fluid of oviduct (SOF) or co-cultured (Expt 2) with an oviduct cell monolayer (OCM) in KSOM or SOF. A total of 3149 cumulus-oocyte complexes obtained by aspirating follicles (2-5 mm diameter) from ovaries of slaughtered animals were selected for IVM and incubated in TCM 199 supplemented with 25 mM HEPES at 39 degrees C in air with 5% CO(2) and maximum humidity for 24 h. In vitro fertilization (IVF) was performed in modified defined medium (mDM) medium. Eighteen hours after IVF, cumulus cells were removed and presumptive zygotes were randomly allocated to the experimental groups. Zygotes cultured (Expt 1) in KSOM + retinol, KSOM, SOF + retinol and SOF were incubated in maximum humidity at 39 degrees C, 5% CO(2), 5% O(2) and 90% N(2). Zygotes co-cultured (Expt 2) in KSOM + retinol + OCM, KSOM + OCM, SOF + retinol + OCM and SOF + OCM were incubated at 39 degrees C, 5% CO(2). In both experiments media were partially changed 48 h after IVF and unfertilized ova were removed. Afterwards embryos were kept in culture or co-culture for further 9 days. In Expt 1, blastocyst rates (day 7) were 14.6% (KSOM + retinol), 15.8% (KSOM), 16.4% (SOF + retinol) and 15.9% (SOF). In Expt 2, the blastocyst rates (day 7) were 25.4% (KSOM + retinol + OCM) 14.2% (KSOM + OCM), 24.3% (SOF + retinol + OCM) and 15.9% (SOF + OCM). The same influence profile of retinol was observed in the formation of the expanded (day 9) and hatched (day 11) blastocysts. The results obtained in Expt 2 demonstrated that the addition of 0.28 microg/ml retinol to the embryo culture media used in this study had a significant (p < 0.05) positive effect on bovine early embryonic development, under the conditions tested, and can be used to enhance in vitro embryo production.

A high yield method for growing primary canine keratinocytes

From a small amount of starting material, a large quantity of canine keratinocytes can be generated for experimental purposes using a refined method of explant culture to initiate the growth of basal cells with a high proliferative potential. The dividing capacity of cultures was promoted by a system selecting clonogenic cells onto an i3T3 feeder layer in combination with carefully monitoring cell morphology and passaging to select out excessive numbers of differentiated keratinocytes. Levels of contaminating dermal fibroblasts, which if left unchecked will overgrow keratinocytes, were kept to a minimum by a combination of careful explant micro-dissection to remove dermis, eliminating explants with signs of fibroblast growth as well as using cholera toxin, EGF and i3T3 feeder layers. The advantage of the method described is that it does not rely on the provision of large quantities of starting material thereby reducing the need for repeated tissue sampling, and passage numbers of five or six can be routinely achieved. This technique can therefore be useful to experimenters who require a regular and reliable source of cells for their studies.

In vitro Capacitation and Acrosome Reaction of Dog Spermatozoa can be Feasibly Attained in a Defined Medium Without Glucose

Incubation of dog spermatozoa in a medium without glucose and in the presence of lactate and pyruvate (l-CCM) for 4 h at 38.5 degrees C in a 5% CO(2) atmosphere induced in vitro capacitation of these cells. This was verified after the combined specific capacitation-like changes in percentages of viability and altered acrosomes, motility characteristics, sperm location of reactivity against Pisum sativum, Arachis hypogaea and Helix pomatia lectins and the tyrosine phosphorylation pattern. Furthermore, a feasible acrosome reaction (AR) was induced when spermatozoa incubated in l-CCM for 4 h were further co-incubated for 1 h with canine oocytes. This was demonstrated by AR-like changes in percentages of viability, altered acrosomes, motility characteristics and sperm location of reactivity against P. sativum, A. hypogaea and H. pomatia lectins. All these results clearly indicate that in vitro capacitation, and subsequent AR, can be feasibly achieved without the presence of sugars. This ability can be related to the specific characteristics of energy-metabolism regulation reported in dog spermatozoa.

Bovine metalloprotease characterization and in vitro connective tissue degradation1

Metalloproteases that selectively hydrolyze connective tissue proteins may tenderize meat without creating texture problems associated with myofibrillar protein degradation. Our objective was to characterize the activity of bovine placental proteases to determine whether they can improve meat tenderness through disruption of the connective tissue matrix. Enzymes were extracted, crudely purified, and proteolytic activity was assessed against gelatin and collagen under varying pH and temperature conditions using both SDS-PAGE and zymography. Gelatin zymography revealed proteolysis between 57 and 63 kDa, with decreased activity as buffer pH decreased from pH 7.4 to 5.4 (37 degrees C). Proteolytic activity was pronounced at 37 degrees C, moderate at 25 degrees C, and absent at 4 degrees C following 48-h incubation (pH 7.4). Placental enzymes were metalloproteases inhibited by excess EDTA. Maximum proteolysis was achieved in the presence of Ca2+, with or without Mg2+ and Zn2+. Absence of Ca2+ decreased proteolytic activity. Complete degradation of both the 125- and 120-kDa proteins of the alpha-chains of gelatin was achieved following enzyme incubation for 6 h at 37 degrees C or 24 h at 25 degrees C. No degradation was observed following enzyme incubation with native Type I collagen. Given the marked decrease in enzyme activity at pH 5.4 and 4 degrees C (standard industry conditions), bovine placental metalloproteases would not be expected to contribute to connective tissue degradation or improve meat tenderness.

Alginate as a new biomaterial for the growth of porcine retinal pigment epithelium

OBJECTIVE

Determine the effect of a 3-dimensional alginate matrix on the growth and differentiation of cells isolated from porcine retinal pigment epithelium (RPE).

PROCEDURES

Porcine RPE cells were harvested from enucleated eyecups, isolated by differential gravity sedimentation and cultured in either alginate alone (Group 1) or on plastic tissue culture plates followed by alginate (Group 2). Group 1 cells were cultured in alginate to evaluate the efficacy of the matrix as a culture medium. Group 2 cells were initially cultured on plastic to induce dedifferentiation. The cells were then harvested, suspended in alginate beads, and incubated for a second culture period to determine if the induced dedifferentiation was reversible.

RESULTS

The number of Group 1 cells was significantly greater (P < or = 0.01) at the end of the culture period. The amount of pigment and cell morphology of Group 1 cells at the end of the culture period was similar to that seen at initial cell isolation. The initial culture of Group 2 cells on plastic showed characteristic features of dedifferentiation marked by the loss of pigment and alterations in microscopic appearance. Secondary culture of dedifferentiated Group 2 cells in alginate beads resulted in a return to pigmentation and characteristic morphology for a majority of the cultured cells.

CONCLUSIONS

Porcine RPE cells can be propagated in alginate culture with a significant increase in cell numbers while maintaining normal morphology. Under the conditions described in the present study, the dedifferentiation of porcine RPE induced by standard in vitro culture methods is reversible.

Effect of capacitation of stallion sperm with polyvinylalcohol or bovine serum albumin on penetration of bovine zona-free or partially zona-removed equine oocytes

Experiments were conducted to study effects of macromolecules on stallion sperm capacitation and fertilization as determined by penetration of bovine zona-free and equine partially zona-removed oocytes. Stallion sperm were capacitated in TYH medium (modified Krebs-Ringer bicarbonate) supplemented with either 1 mg/mL of polyvinylalcohol (PVA) or 4 mg/mL of BSA. Capacitation was induced with 8 bromoadenosine cyclic monophosphate (8BrcAMP; 0.5 mM) alone or in combination with 0.1 microM of ionomycin. Intraspecies gametes were co-incubated in TYH/PVA or TYH/BSA for 18 to 20 h. For zona-free bovine oocytes, penetration rate (35%) with the combination of 8BrcAMP and ionomycin in PVA-containing medium was higher (P < 0.05) than any treatment in BSA-containing medium (5 to 6%). A similar study was conducted using equine oocytes with partially removed zonae. Sperm capacitated and used for in vitro fertilization (IVF) in PVA-containing medium had higher penetration rates (P < 0.01) than sperm in BSA-containing medium (54 vs. 11%). The effect of equine preovulatory follicular fluid on bovine oocyte penetration was assessed. Bovine oocytes were matured in tissue culture medium-199 with 0, 20, 50, or 100% equine preovulatory follicular fluid, and 1 IU/mL of equine chorionic gonadotropin. Stallion sperm were treated with 8BrcAMP + ionomycin in PVA- or BSA-containing media. The penetration rates of bovine zona-free oocytes by stallion sperm were again higher with PVA (47%) than BSA (18%; P < 0.01). Penetration rates of oocytes matured in 100% follicular fluid were higher (P < 0.05) than for oocytes matured with 0% follicular fluid. The effects of equine follicular fluid and PVA/BSA during sperm capacitation on standard bovine IVF were examined. Culture of bovine oocytes with equine follicular fluid did not affect oocyte maturation or penetration rates after IVF. Bovine sperm capacitated with heparin in PVA-containing medium yielded lower (P < 0.05) fertilization rates than those capacitated in BSA-containing medium when incubated with both zona-intact and zona-free bovine oocytes. In summary, PVA was superior to BSA for ionophore-induced capacitation of equine sperm for penetration of zona-free bovine oocytes or partially zona-removed equine oocytes, but not for standard bovine IVF with bovine sperm. Zona-free bovine oocytes may be useful for assaying in vitro capacitation and fertilization of stallion sperm.

Insight into the mechanism of short chain fatty acid absorption in the ostrich (Struthio camelus) proximal colon

1. Occurrence of short chain fatty acids (SCFA) in anionic form limits their diffusion across the absorptive membrane. The present study sought to establish the mechanism of SCFA absorption in the ostrich. 2. Epithelial tissues were taken from the sacculated part of the colon and mounted in Ussing chambers in a bathing solution. The tissues were voltage-clamped and allowed to equilibrate to obtain a baseline short circuit current (Isc). 3. Propionate (23 mM) on the mucosal side increased the Isc. The SCFA-induced Isc was completely inhibited by anoxia, ouabain (1 to 2 mM), acetazolamide (0.5 mM) and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.1 mM) on the mucosal side. 4. These findings indicate that SCFA stimulate hydrogen ion secretion through an electrogenic H(+)-K(+)-ATPase, the source of hydrogen ions being carbonic anhydrase catalysed hydration of CO2. 5. Simultaneous activation of Cl(-)/HCO3(-) exchange prevents intracellular accumulation of bicarbonate ions. This system may provide hydrogen ions for protonation of SCFA anions and subsequent absorption by non-ionic diffusion.

Insulin and (or) dexamethasone effectson leptin production and metabolic activitiesof ovine adipose tissue explants

The in vitro effects of insulin and/or dexamethasone (DEX) on leptin production were studied on adipose tissue (AT) from adult non-lactating, non-pregnant ewes. Perirenal AT explants were incubated for 2 or 4 days and leptin production was determined using a specific ovine RIA. The effects of these hormones were simultaneously measured on glucose and acetate utilisation and on lipogenic enzyme activities. A preliminary dose-response study showed a maximal leptin production by the addition in the incubation medium of 2 mIU x mL(-1) of insulin and 100 nM of DEX. By using these concentrations, insulin or DEX increased leptin production by ovine AT explants whatever the incubation duration and the effects of these two hormones were additive. Insulin also increased substrate utilisation as well as lipogenic enzyme activities while DEX decreased substrate utilisation and did not change the lipogenic enzyme activities. To conclude, leptin response to DEX is specific and largely independent of the overall metabolic or lipogenic activity.

In vitro and in vivo comparison of Ham's F-10, Emcare holding solution and ViGro holding plus for the cooled storage of equine embryos

Equine embryos have been successfully transferred after 24h cooled storage in Ham's F-10. The aim of this study was to compare the viability of equine embryos in vitro and in vivo after 6 and 24h cooled storage using three media and to examine the relationship between embryo size and viability after 24h cooled storage. In Experiment 1, the viability of embryos was evaluated using DAPI-staining after 0, 6 or 24h in Ham's F-10, 24h in Emcare embryo holding solution (EHS) or 24h in ViGro holding plus (VHP) (n=10/group). The mean number of dead cells was similar for embryos stored in Ham's F-10, EHS and VHP for 24h. Larger Day 7 embryos appear to withstand 24h cold storage better than small Day 7 embryos. The embryo quality for 24h cold storage was negatively correlated with size. In Experiment 2, 40 embryos were stored (n=20/group) either in Ham's F-10 or in EHS then transferred as pairs in recipient mares. Fifteen of the 20 recipient mares (75%) were pregnant. Out of 17 surviving embryos, 9 embryos (53%) were stored in Ham's F-10 and 8 (47%) in EHS. These results suggest that EHS and VHP offer a good alternative to Ham's F-10 for 24h cooled storage of equine embryos and that larger embryos may have a better viability after 24h of cooled storage than smaller embryos.

Use of two replacements of serum during bovine embryo culture in vitro

This study evaluated the effect of two commercial serum replacements (Ultroser G and CPSR-3 on in vitro bovine embryo culture. In Experiment 1, zygotes were cultured in SOF+Ultroser G (2, 4 and 6%), SOF+CPSR-3 (2, 4 and 6%), and SOF+5% FCS (control). Blastocyst rates obtained after culturing with Ultroser G were lower than those with FCS. However, blastocyst rates for CPSR-3 were similar to those for serum. In addition, embryos produced in SOF+CPSR-3 had the same proportion inner cell mass number and total cell number as embryos cultured with FCS. In Experiment 2, a combination of serum replacements during different periods showed that treatment before the five-to eight-cell stages had no effect on further embryo development. However, treatments up to the morula stage affected blastocyst formation. The concentration of supplement and the timing of its inclusion in culture markedly affected embryo development. The serum replacement CPSR-3 can supplement embryo culture with blastocyst rates and quality similar to those for serum.

Inhibition of articular cartilage degradation by glucosamine-HCl and chondroitin sulphate

Glucosamine and chondroitin sulphate in many animal and human trials has improved joint health. In vitro studies are beginning to clarify their mode of action. The objective of this research was to: 1) determine at what concentrations glucosamine-HCl (GLN) and/or chondroitin sulphate (CS) would inhibit the cytokine-induced catabolic response in equine articular cartilage explants and 2) to determine if a combination of the 2 was more effective at inhibiting the catabolic response than the individual compounds. Articular cartilage was obtained from carpal joints of horses (age 1-4 years). Cartilage discs (3.5 mm) were biopsied and cultured. Explants were incubated with lipopolysaccharide (LPS) in the presence of varying concentrations of GLN, CS, or both. Control treatments included explants with no LPS and LPS without GLN or CS. Media were analysed for nitric oxide (NO), prostaglandin E2 (PGE2) and keratan sulphate. Cartilage was extracted for analysis of metalloproteinases (MMP). Four experiments were conducted. In all experiments, GLN at concentrations as low as 1 mg/ml decreased NO production relative to LPS stimulated cartilage without GLN over the 4 day period. In general, CS at either 0.25 or 0.5 mg/ml did not inhibit NO production. The addition of CS to GLN containing media did not further inhibit NO production. GLN at concentrations as low as 0.5 mg/ml decreased PGE2 production, whereas CS did not effect on PGE2. The combination of GLN/CS decreased MMP-9 gelatinolytic activity but had no effect on MMP-2 activity. The combination in 2 experiments tended to decrease MMP-13 protein concentrations and decreased keratan sulphate levels in media. Overall, the combination of GLN (1 mg/ml) and CS (0.25 mg/ml) inhibited the synthesis of several mediators of cartilage degradation. These results further support the effort to understand the role of GLN and CS in preserving articular cartilage in athletic horses.

Characterisation of reconstituted equine cartilage formed in vitro

Lesions in cartilage of equine weightbearing joints commonly result in lameness. Cell-based resurfacing techniques are currently being developed for human and veterinary applications. Biopsies of stifle joint cartilage (1 g) were harvested aseptically and chondrocytes were isolated by sequential enzyme digestion. The cells were grown in vitro on filter inserts. Analysis of cultures 8 weeks later showed that the cells had accumulated extracellular matrix and formed a continuous layer of cartilagenous tissue as determined histologically. The cells maintained their phenotype as they synthesised type II collagen and proteoglycans similar in size to those synthesised by chondrocytes in native cartilage, but this reconstituted tissue had more sulphated glycosaminoglycan and lower collagen content than native cartilage. This experiment tests the feasibility of growing equine cartilagenous tissue in vitro. This tissue may be useful in the management of chondral injuries in the horse in a scenario where the patient donates cells, the cells are propagated under laboratory conditions and the resulting tissue becomes the therapeutic agent.

In vitro investigation of the interaction between nitric oxide and cyclo-oxygenase activity in equine ventral colon smooth muscle

The objective of this study was to determine if a correlation exists between the presence of nitric oxide and prostaglandin release in the equine ventral colon smooth muscle, since this relationship may accentuate the inflammatory process during intestinal injury. Tissue was collected from the ventral colon, cut into muscle strips oriented along the circular, longitudinal and taenial layers, and mounted in a tissue bath system. Samples of the bath fluid were collected before, following electrical field stimulation (EFS), and following EFS in the presence of L-NAME, a nitric oxide synthase inhibitor. Muscle strips were also obtained following systemic administration of a cyclo-oxygnease inhibitor and samples were collected using the previously described protocol. Concentrations of prostaglandins were determined in the fluid samples using an ELISA. Electrical field stimulated release of nitric oxide produced a significant increase in prostaglandin production which did not occur in the presence of L-NAME. Systemic administration of flunixin meglumine reduced prostaglandin levels at all sampling periods, although a small increase was present following EFS. The results of this study support the hypothesis that there is a correlation between the release of nitric oxide and the production of prostaglandins in the smooth muscle of the large colon. This association between nitric oxide and prostaglandin may act as an important regulatory mechanism for various physiological mechanisms, such as vascular smooth muscle tone, and may contribute to amplified tissue injury when the induced forms of both enzymes are activated during an inflammatory insult. This suggests that the use and development of COX2 and iNOS inhibitors may help attenuate the inflammatory response following intestinal injury.

Changes in the population of immunoreactive S-100-positive folliculo-stellate cells in hens during induced molting

The goal of this study was to determine whether the population of folliculo-stellate (FS) cells in the hen's pituitary change during induced molting. White Leghorn laying hens were subjected to induced molting by feed withdrawal; feeding was resumed on the fourth day after egg laying ceased. The anterior pituitaries were collected from hens at pretreatment, at 3 and 5 d after feed withdrawal and at 3 d after cessation of egg laying, 10 d after cessation of egg laying (6 d after resumption of feeding), on the day of and 1 wk after resumption of egg laying (RL and 1WRL, respectively). Pituitaries were processed to detect FS cells by immunocytochemistry for the S-100 protein. Sections were then examined under a light microscope with an image analysis computer system. S-100 immunoreactive cells were found in the cephalic and caudal lobes of the anterior pituitary in all groups of hens. The majority of S-100 immunoreactive cells formed clusters of cells that faced into the follicle and surrounded the glandular cells with long cytoplasmic processes. The S-100 immunoreactive area in the cephalic lobe was significantly increased in the RL group (P < 0.05), but decreased thereafter in 1WRL group. The S-100-positive cell area in the caudal lobe did not show significant changes during induced molting. These results suggest that FS cell population is likely to increase at the final stage of induced molting and may be involved in control of pituitary functions for the resumption of ovulation.

In vitro production of embryos in swine

In recent years, progress has been achieved in the production of pig embryos through IVM and IVF techniques. Cytoplasmic maturation of oocytes has been improved by modifications to IVM procedures. However, the historical problem of polyspermic penetration still remains a major issue to be solved. Recent studies indicate that the type of IVF medium and certain modifications to that medium can reduce polyspermy. Efforts should be directed to increase the developmental competence and quality of embryos. At present, many embryo culture (EC) media are available that can overcome the historical 4-cell block and support development of early in vivo derived embryos to the blastocyst stage. In contrast, blastocyst development of in vitro produced embryos in these culture media varies significantly. Furthermore, morphology and cell numbers in in vitro produced blastocysts are inferior to their in vivo counterparts. However, several modifications to EC techniques have improved embryo quality and developmental competence. Testing embryo viability through surgical transfer to recipient animals has resulted in acceptable pregnancy rates with moderate litter sizes. Although reliable in vitro systems are available for the generation of pig embryos, the problem of polyspermy and poor embryo development hamper their large-scale implementation. Further research efforts should be directed to improve oocyte/embryo quality and the methods to minimize polyspermy through development of novel IVM, IVF, and EC techniques.

Effects of bethanechol on canine urinary bladder smooth muscle function

We studied whether the effects of bethanechol are mediated via a muscarinic receptor, the role of extracellular calcium on bladder contraction, and down-regulation of bladder contraction by bethanechol after activation with potassium chloride (KCl) and acetylcholine (Ach). Smooth muscle strips of normal urinary bladder were studied with standard methods to measure isometric force. Bethanechol caused a dose-dependent increase in bladder contraction. The potency of bethanechol is higher than Ach, as shown by higher peak active isometric stress (P(max)) and lower half-maximal contraction (ED(50)) (P< 0.01). The contractile responses to bethanechol were diminished in the presence of atropine, nifedipine and in calcium-free medium as shown by P(max) decreased by 58%, 87% and 65% and ED(50) increased by 314-, 24- and 16-fold, respectively. When bladder strips were stimulated with KCl and Ach, pre-treatment with bethanechol reduced the responses to KCl by 116-242% (P<0.05), while the contractile responses to Ach were unaltered. Thus, bethanechol induces bladder contraction via muscarinic receptor activation while both intracellular and extracellular calcium play a crucial role on bladder smooth muscle contraction. The mechanisms of down-regulation by bethanechol may be related to interference with calcium influx into the smooth muscle cells, rather than the desensitisation of muscarinic receptors or post-receptor steps of signal transduction following bethanechol binding to the receptor.

Handling and culture of bovine embryos: survey of media used by 26 embryo transfer companies in the USA

Embryo transfer has evolved from a few highly centralized clinics to a widespread number of clinics offering both clinic and on-the-farm services. Practitioners in the field have made very few changes in the handling and culture of embryos. A short review of general handling techniques, plus a survey of media used by 26 companies in the USA, is presented here. Currently, phosphate-bufferend saline (PBS) plus two other commercially available media (EMCARE and ViGro) are used by these companies. Fourteen different combinations of these products were reported and only 11 of the 26 consistently used the same medium for flushing, culture and freezing.

Isolation of Neospora caninum from the brain of a naturally infected dog, and production of encysted bradyzoites in gerbils

Neospora caninum was isolated from the brain of an adult dog in Brazil. Cerebral tissue from the dog was inoculated into Mongolian gerbils. Gerbils were euthanized 3-4 months later and bradyzoite-containing tissue cysts were observed in their brains. N. caninum (designated NC-Bahia) was isolated in cell culture after inoculation with tissue cysts from the gerbils. The identity of the parasite was confirmed by immunohistochemical examination and polymerase chain reaction (PCR). Gerbils may be a useful alternative to immunosuppressed mice for isolation of N. caninum and for production of encysted bradyzoites.

Developmental competence of bovine embryos reconstructed by the transfer of somatic cells derived from frozen tissues

The ability of frozen-thawed fetal skin was examined to generate viable cell lines for nuclear transfer. Fetal skin frozen at -35 degrees C or -80 degrees C in the presence of 5% DMSO were used as tissue explants to generate somatic cells. The resultant confluent cells were then used as donors for nuclear transfer (NT). Of the bovine NT embryos reconstructed from the somatic cells, 78% to 81% showed cleavage, 43% to 48% reached the stage of morula formation and 34% to 35% reached blastocyst formation. There were no significant differences in development (P>0.05) when the NT embryos were compared with those reconstructed from fresh somatic-cell-derived skin tissues (75%, 45%, and 38%, for cleavage, and development to morula and blastocyst stages, respectively). The results indicated that cell lines derived from bovine fetal skin cryopreserved by a simple method could be used as donors in nuclear transfer. The resulting embryos showed similar development in vitro to those reconstructed from unfrozen fetal-skin-derived somatic cells.

In vitro viral haemorrhagic septicaemia virus replication in excised fins of rainbow trout: correlation with resistance to waterborne challenge and genetic variation

In vitro viral haemorrhagic septicaemia virus replication in excised fin tissue (VREFT) was investigated as a possible criterion to predict the resistance of groups or individuals to viral haemorrhagic septicaemia virus (VHSV) in rainbow trout. Adipose and rayed fins were compared for VREFT response, and a statistically significant correlation was found. Correlation between VREFT and survival after waterborne viral challenge was estimated on a set of 27 groups of trout, and was highly significant (R = 0.72). A further experiment with fish individually tagged and challenged some time after fin clipping for determination of VREFT confirmed that the mean value of resistant (surviving) fish was significantly lower than the mean value of susceptible (dead) ones, but there was a wide variation within each of these groups. In particular, a large proportion of fish expected to be resistant based on VREFT values died all the same. Using clones, we showed that the correlation between VREFT and survival was dramatically high (R = 0.96). Genetic analyses of the data from the different groups available in the experiment consistently indicated a large amount of genetic determination of VREFT, an encouraging result for selection purposes. Though these results were obtained in experimentally controlled conditions not identical to those in the field, they shed new light on the analysis of defence mechanisms against the virus and on the possibility of performing indirect selection for resistance, using VREFT as the secondary character.

Decrease of the adhesion of Streptococcus suis serotype 2 mutants to embryonic bovine tracheal cells and porcine tracheal rings

Streptococcus suis is an important swine pathogen that may be present in the tonsils of pigs that show no signs of illness. Because adhesion to host cells may be important in the carrier state, this study was undertaken to investigate adhesion to host cells by S. suis mutant strains defective in expression of a 39-kDa protein. Mutant strains of S. suis were generated by transposon Tn916 mutagenesis and were tested for adhesion to embryonic bovine tracheal cells and porcine tracheal rings. Compared with the parent strain, there was a significant reduction in adherence of 3 mutant strains to both bovine tracheal cells and porcine tracheal rings.

Effect of lectins on the invasion of Ichthyophthirius theront to channel catfish tissue

This study determined the effects of lectin binding to theronts of Ichthyophthirius multifiliis on theront immobilization, invasion, trophont development and survival in channel catfish Ictalurus punctatus excised fins in vitro. Soybean agglutinin (SBA), lentil agglutinin (LCA), gorse agglutinin (UEA-I) and wheat germ agglutinin (WGA) were used to treat theronts. Percentages of theronts immobilized by 4 lectins ranged from 12.0 to 19.4% at a concentration of 1000 microg ml(-1). These lectins bound more than half of the theronts at a concentration of 50 microg ml(-1). More theronts were labeled by SBA and WGA than by lectin LCA at concentrations of 50 and 100 microg ml(-1), respectively. The binding of these lectins to theronts indicated that monosaccharides (D-galactose, L-fucose, D-mannose and D-glucose) and amino sugar derivatives (N-acetylgalactosamine and N-acetylglucosamine) were present on the surface of theronts. Invasion was reduced significantly for theronts treated with LCA, UEA-I and WGA. No difference in invasion was found between control and SBA bound theronts (p > 0.05). The binding of lectin LCA, UEA-I and WGA to theronts significantly reduced the development of trophonts (p < 0.05). The mean volumes of trophonts labeled with these 3 lectins were smaller than volumes in control trophonts from 8 to 48 h after exposure. Survival was lower in trophonts labeled with lectins than in control trophonts at 48 h after exposure.

Evaluation of the dermatophyte test medium RapidVet-D

The performance of the dermatophyte test medium (DTM) RapidVet-D was assessed using hair samples collected from experimentally infected guinea pigs. Three dermatophyte species were included in the study: Microsporum canis, Trichophyton mentagrophytes and Trichophyton equinum. DTM substrates were inoculated with infected hairs and scales, incubated at 18, 21, 24, 27 or 37 degrees C and examined daily for 15 days. The rapidity of colour change was clearly related to the incubation temperature and to the number of infected hairs deposited on the reactive substrates. With the optimum incubation temperature 27 degrees C, a systematic colour change could be observed only a few days post-inoculation: 3 days with M. canis infected hairs, 4 days with T. equinum and 5 days with T. mentagrophytes.

Effects of oligosaccharides on functional parameters of the intestinal tract of growing pigs

Feeding experiments were carried out in growing pigs using topinambur powder or inactivated yeasts as prebiotic additives with an application period of at least 3 weeks. At the end of the experimental periods the animals were killed and segments of the intestinal tract were used for measuring transport physiological parameters and for mucin histochemistry. Jejunal epithelia were mounted in Ussing chambers for measuring electrical tissue parameters, paracellular permeability and short circuit current response to mucosal glucose. Both prebiotics had no effects on basal or forskolin stimulated short circuit currents. Total tissue conductances tended to be higher in response to both prebiotics. Topinambur increased mucosal-to-serosal fluxes of mannitol in the proximal and distal jejunum, which could only be demonstrated for the distal jejunum when inactivated yeasts were fed. Mucosal application of glucose induced higher current responses in jejunal tissues. From histochemistry it could be demonstrated that both prebiotics increased the number of ileal goblet cells and the thickness of the colonic mucosa.

Comparison of Gonadal Hormone Levels in Turkey Embryos Incubated in Long-Term Shell-Less Culture and In Ovo

Changes in concentrations of 17beta-estradiol (E2) and androgenic hormones were measured in turkey embryos incubated in long-term, shell-less culture (ex ovo) and in ovo. Blood samples were obtained from both sets of embryos on Days 14, 16, 18, 20, and 22 and from embryos incubated in ovo on Days 24, 26, and 28. Ex ovo and in ovo embryos showed no differences in either hormone within sexes, with one exception. On Day 14 of incubation, the ex ovo females had higher (P < 0.05) E2 levels (55.6+/-5.1 pg/mL) than the in ovo females (32.2+/-2.3 pg/mL); however, this result might have been due to the small sample size (n = 3) for ex ovo females. No significant differences were found in androgen concentrations between sexes in ovo on Days 24, 26, and 28 of incubation. However, on Days 24, 26, and 28, in ovo females showed highly significant differences (P < 0.01) in E2 compared with males of the same age. These results indicate a similar developmental pattern for the endocrine system in ovo and ex ovo through Day 22 of incubation. Further, there were sex differences in E2 that are likely to be critical for sexual differentiation that emerges late in embryonic development.