Toll-like receptor 4 mediates the response of epithelial and stromal cells to lipopolysaccharide in the endometrium

BACKGROUND

Ascending infections of the female genital tract with bacteria causes pelvic inflammatory disease (PID), preterm labour and infertility. Lipopolysaccharide (LPS) is the main component of the cell wall of Gram-negative bacteria. Innate immunity relies on the detection of LPS by Toll-like receptor 4 (TLR4) on host cells. Binding of LPS to TLR4 on immune cells stimulates secretion of pro-inflammatory cytokines such as IL-6, chemokines such as CXCL1 and CCL20, and prostaglandin E(2). The present study tested the hypothesis that TLR4 on endometrial epithelial and stromal cells is essential for the innate immune response to LPS in the female genital tract.

METHODOLOGY/PRINCIPAL FINDINGS

Wild type (WT) mice expressed TLR4 in the endometrium. Intrauterine infusion of purified LPS caused pelvic inflammatory disease, with accumulation of granulocytes throughout the endometrium of WT but not Tlr4(-/-) mice. Intra-peritoneal infusion of LPS did not cause PID in WT or Tlr4(-/-) mice, indicating the importance of TLR4 in the endometrium for the detection of LPS in the female genital tract. Stromal and epithelial cells isolated from the endometrium of WT but not Tlr4(-/-) mice, secreted IL-6, CXCL1, CCL20 and prostaglandin E(2) in response to LPS, in a concentration and time dependent manner. Co-culture of combinations of stromal and epithelial cells from WT and Tlr4(-/-) mice provided little evidence of stromal-epithelial interactions in the response to LPS.

CONCLUSIONS/SIGNIFICANCE

The innate immune response to LPS in the female genital tract is dependent on TLR4 on the epithelial and stromal cells of the endometrium.

Markers of the uterine innate immune response of the mare

Reproductive efficiency in mares is low and persistent mating-induced endometritis (PMIE) is an important cause of subfertility. Mating-induced endometritis (MIE) an obligate precursor to PMIE, is a ubiquitous, transient inflammatory response to the presence of sperm, seminal components and pathogens. However, the specific inflammatory pathways that derive from MIE and that may also be precursors to PMIE are not clear. The ability to identify and measure robust, repeatable markers of inflammation integral to MIE may be key to understanding the progression to PMIE. The aim of the study was to (i) refine a protocol for inducing MIE and in doing so test a range of cellular and molecular parameters as valid markers of MIE to facilitate future studies of mares susceptible to PMIE (ii) concurrently identify those parameters with potential as inflammatory indicators during MIE to inform and enhance early treatment regimens in practice. Mating-induced endometritis was induced in pony mares using a stringent protocol; mares were treated intrauterine with frozen/thawed semen (n = 5; FTS) or frozen/thawed extender (n = 6: FTEx). The parameters tested were measured before treatment were compared to samples collected at strategic time points after treatment: uterine cytology using cytological (at 8, 16, 24, 48 and 72 h after treatment) or histological analysis (at 24 and 72 h); uterine bacteriology (at 24 and 72 h); secretion of prostaglandin F(2alpha) (PGF(2alpha); at 8, 16, 24, 48 and 72 h); peripheral concentrations of serum amyloid A (SAA; at 24h); endometrial mRNA gene expression, focussing upon IL8 and TLR4, as examples of genes pertinent to inflammation (at 24 h). Uterine neutrophil cell numbers in both treatment groups increased at 8 (P < 0.001), 16 (P < 0.01) and 24 (P < 0.01) h after insemination, indicative of MIE and distinguished between different treatments because neutrophil numbers were greater from FTS mares than FTEx mares 8h after challenge. Uterine neutrophil cell numbers, assessed by histology, increased (P < 0.001) 24 and 72 h after treatment. Prostaglandin F(2alpha) concentrations increased (P < 0.05) 16 h after treatments, while SAA concentrations and bacterial growth scores were not significantly different after treatment. Endometrium from pony mares expressed mRNA for IL8 and TLR4 but expression was not altered after insemination. The protocol induced MIE, as confirmed by uterine cytology and maybe used hereafter as a repeatable and robust method for studying immune mechanisms that underlie MIE and so may aid the understanding of progression to persistent inflammation. It can be concluded that of the range of parameters tested, neutrophil cell numbers by cytological analysis and PGF(2alpha) were regarded as the most accurate markers of inflammation during MIE and important for use in practice.

Mechanisms of infertility associated with clinical and subclinical endometritis in high producing dairy cattle

Clinical and subclinical endometritis are common causes of infertility and subfertility in high producing dairy cattle, delaying the onset of ovarian cyclic activity after parturition, extending luteal phases and reducing conception rates. Escherichia coli and Arcanobacterium pyogenes cause endometrial damage and inflammation. Components of microbes, such as lipopolysaccharide (LPS), are detected by Toll-like receptors on endometrial cells, leading to secretion of cytokines, chemokines and antimicrobial peptides. Long luteal phases associated with endometritis are probably caused by a switch in endometrial prostaglandin production from prostaglandin F2a (PGF) to prostaglandin E2. In addition, LPS impairs the function of the hypothalamus and pituitary, and directly perturbs ovarian granulosa cells steroidogenesis, providing mechanisms to explain the association between uterine disease and anovulatory anoestrus. Cows with uterine disease that ovulate have lower peripheral plasma progesterone concentrations that may further reduce the chance of conception associated with endometritis.

Isolation and characterization of bovine herpesvirus 4 (BoHV-4) from a cow affected by post partum metritis and cloning of the genome as a bacterial artificial chromosome

BACKGROUND

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus with a Worldwide distribution in cattle and is often isolated from the uterus of animals with postpartum metritis or pelvic inflammatory disease. Virus strain adaptation to an organ, tissue or cell type is an important issue for the pathogenesis of disease. To explore the mechanistic role of viral strain variation for uterine disease, the present study aimed to develop a tool enabling precise genetic discrimination between strains of BoHV-4 and to easily manipulate the viral genome.

METHODS

A strain of BoHV-4 was isolated from the uterus of a persistently infected cow and designated BoHV-4-U. The authenticity of the isolate was confirmed by RFLP-PCR and sequencing using the TK and IE2 loci as genetic marker regions for the BoHV-4 genome. The isolated genome was cloned as a Bacterial Artificial Chromosome (BAC) and manipulated through recombineering technology

RESULTS

The BoHV-4-U genome was successfully cloned as a BAC, and the stability of the pBAC-BoHV-4-U clone was confirmed over twenty passages, with viral growth similar to the wild type virus. The feasibility of using BoHV-4-U for mutagenesis was demonstrated using the BAC recombineering system.

CONCLUSION

The analysis of genome strain variation is a key method for investigating genes associated with disease. A resource for dissection of the interactions between BoHV-4 and host endometrial cells was generated by cloning the genome of BoHV-4 as a BAC.

Endometrial explant culture to study the response of equine endometrium to insemination

Mating-induced endometritis (MIE) is ubiquitous in the horse after natural mating and artificial insemination with frozen/thawed semen causing the most aggressive response. The majority of mares eliminate MIE 24-48 h after insemination. An endometrial explant culture was tested as a potential in vitro exemplar for sperm-induced MIE. Endometrial prostaglandin F(2alpha) (PGF(2alpha)) secretion and expression of interleukin-8 (IL-8) were used as markers of inflammation. Endometrial explants were cultured from uteri collected from follicular phase mares. Explants were challenged with 1 or 10 x 10(6) sperm/ml frozen/thawed semen, chilled semen, washed sperm or seminal plasma. Medium was collected 24 and 72 h after challenge and assayed for PGF(2alpha) by radioimmunoassay. Treatment of endometrial explants with frozen/thawed, chilled semen or washed sperm did not change the secretion of PGF(2alpha) compared with untreated controls. However, 24 h after challenge cultured explants expressed IL-8. The in vitro endometrial explant system did not represent the in vivo response to semen when PGF(2alpha) was used as a marker of inflammation, yet the use of gene expression as an inflammatory marker warrants further investigation.

Bovine endometrial stromal cells display osteogenic properties

The endometrium is central to mammalian fertility. The endometrial stromal cells are very dynamic, growing and differentiating throughout the estrous cycle and pregnancy. In humans, stromal cells appear to have progenitor or stem cell capabilities and the cells can even differentiate into bone. It is not clear whether bovine endometrial stromal cells exhibit a similar phenotypic plasticity. So, the present study tested the hypothesis that bovine endometrial stromal cells could be differentiated along an osteogenic lineage. Pure populations of bovine stromal cells were isolated from the endometrium. The endometrial stromal cell phenotype was confirmed by morphology, prostaglandin secretion, and susceptibility to viral infection. However, cultivation of the cells in standard endometrial cell culture medium lead to a mesenchymal phenotype similar to that of bovine bone marrow cells. Furthermore, the endometrial stromal cells developed signs of osteogenesis, such as alizarin positive nodules. When the stromal cells were cultured in a specific osteogenic medium the cells rapidly developed the characteristics of mineralized bone. In conclusion, the present study has identified that stromal cells from the bovine endometrium show a capability for phenotype plasticity similar to mesenchymal progenitor cells. These observations pave the way for further investigation of the mechanisms of stroma cell differentiation in the bovine reproductive tract.

Bacterial infection of endometrial stromal cells influences bovine herpesvirus 4 immediate early gene activation: a new insight into bacterial and viral interaction for uterine disease

Experimental infection with the gamma-herpesvirus bovine herpesvirus 4 (BoHV-4) rarely establishes disease, yet BoHV-4 is commonly associated with uterine disease in cattle. Uterine disease involves co-infection with bacteria such as Escherichia coli, which stimulate the production of prostaglandin E(2) (PGE(2)) by endometrial cells. BoHV-4 replication depends on immediate early 2 (IE2) gene transactivation and, in the present study, PGE(2), E. coli or its lipopolysaccharide upregulated the IE2 gene promoter in uterine cells. Bacterial co-infection is important for BoHV-4 uterine disease.

Field investigation of perinatal mortality in friesian cattle associated with myocardial degeneration and necrosis

Perinatal mortality and stillbirths were investigated in an extensively managed herd of Friesian cows and heifers calving over a 2-year period: 504 cows were calved and 215 heifers. Cows were bred to Friesian and Jersey bulls using natural service. The perinatal fetal mortality rate was 7.5% for cows and 30% for heifers. An experienced stockman managed these calvings and veterinary assistance was required only on nine occasions. All stillborn fetuses were examined post-mortem by the Veterinary Laboratories Agency, Carmarthen and no infectious agent was identified on any occasion. Thyroid hyperplasia was found in two fetuses. In blood samples taken from 10 late pregnant heifers, mean glutathione peroxidase values were 7.9 +/- 1.7 IU/ml Packed Cell Volume (PCV). Tissues from eight fetuses were submitted to the University of Liverpool for histopathological examination; all presented lesions consistent with myocardial degeneration and necrosis of the left ventricle. Following treatment of 205 late pregnant heifers with sodium selenite and vitamin E, the overall perinatal mortality rate in these cattle fell to below 11%.

Bovine herpesvirus 4 is tropic for bovine endometrial cells and modulates endocrine function

Bovine postpartum uterine disease, metritis, affects about 40% of animals and is widely considered to have a bacterial aetiology. Although the gamma-herpesvirus bovine herpesvirus 4 (BoHV-4) has been isolated from several outbreaks of metritis or abortion, the role of viruses in endometrial pathology and the mechanisms of viral infection of uterine cells are often ignored. The objectives of the present study were to explore the interaction, tropism and outcomes of BoHV-4 challenge of endometrial stromal and epithelial cells. Endometrial stromal and epithelial cells were purified and infected with a recombinant BoHV-4 carrying an enhanced green fluorescent protein (EGFP) expression cassette to monitor the establishment of infection. BoHV-4 efficiently infected both stromal and epithelial cells, causing a strong non-apoptotic cytopathic effect, associated with robust viral replication. The crucial step for the BoHV-4 endometriotropism appeared to be after viral entry as there was enhanced transactivation of the BoHV-4 immediate early 2 gene promoter following transient transfection into the endometrial cells. Infection with BoHV-4 increased cyclooxygenase 2 protein expression and prostaglandin estradiol secretion in endometrial stromal cells, but not epithelial cells. Bovine macrophages are persistently infected with BoHV-4, and co-culture with endometrial stromal cells reactivated BoHV-4 replication in the persistently infected macrophages, suggesting a symbiotic relationship between the cells and virus. In conclusion, the present study provides evidence of cellular and molecular mechanisms, supporting the concept that BoHV-4 is a pathogen associated with uterine disease.

Use of the cow as a large animal model of uterine infection and immunity

For most of the reproductive cycle in both humans and animals, the uterus is clear of pathogenic bacteria. However, it is readily contaminated with pathogens, such as Escherichia and Tritichomonas species, during sexual intercourse and after parturition. Uterine infection is particularly common after parturition in cattle (Bos taurus), causing clinical disease and infertility. The endocrine and immune responses to uterine infection in cattle have been investigated in vivo and using tissue culture. Cattle are of sufficient size to permit monitoring of reproductive and immune function throughout uterine infections, and primary cell cultures are readily established. In the whole animal, uterine infections suppress GnRH and LH secretion, and inhibit the growth of ovarian follicles and their estradiol secretion. The immune response is characterized by an influx of neutrophils into the uterus and increased concentrations of acute phase proteins in peripheral plasma. In vitro, the endometrial and ovarian cell function is modified by challenge with bacteria, their products such as lipopolysaccharide or pro-inflammatory cytokines. However, it is interesting to note that the susceptibility to uterine infection and the immune response are partially regulated by the ovarian steroid hormone mileu. In conclusion, the ease of working with cattle, the availability of tissues and the similarity of uterine infection between mammals, make Bos taurus a good model for studying uterine infection and immunity.

Minimum inhibitory concentrations of some antimicrobial drugs against bacteria causing uterine infections in cattle

The minimum inhibitory concentrations (MICs) of oxytetracycline, cephapirin, cephapirin/mecillinam, cefquinome, ceftiofur and enrofloxacin, candidate antibiotics for the principal bacteria associated with uterine infections: Escherichia coli, Arcanobacterium pyogenes and the anaerobic bacteria Fusobacterium necrophorum and Prevotella melaninogenicus, were determined by the agar dilution method. The bacteria were isolated from animals with clinical metritis and/or endometritis. For E coli, cefquinome and enrofloxacin had the lowest MIC90 and MIC50 values (< 0.06 microg/ml), and oxytetracycline and cephapirin had the highest values. For A pyogenes, oxytetracycline had the highest MIC50 value (16 microg/ml), but all the cephalosporins had values below 0.06 microg/ml. For the anaerobic bacteria, enrofloxacin and oxytetracycline had the highest MIC50 values but all the cephalosporins had values of 0.06 microg/ml or below.

Postpartum uterine health in cattle

Uterine health is often compromised in cattle because postpartum contamination of the uterine lumen by bacteria is ubiquitous, and pathogenic bacteria frequently persist causing clinical disease. The subfertility associated with uterine infection involves perturbation of the hypothalamus, pituitary and ovary, in addition to the direct effects on the uterus, and appears to persist even after clinical resolution of the disease. Absorption of bacterial components from the uterus can prevent the follicular phase LH surge and ovulation. In addition, the first postpartum dominant follicle has a slower growth rate and secretes less estradiol at the end of the growth phase. There are also localised ovarian effects of high uterine bacterial growth density, because fewer first dominant follicles are selected in the ovary ipsilateral than contralateral to the previously gravid uterine horn. Thus, it is important to diagnose and treat uterine disease promptly and effectively. Examination of the contents of the vagina for the presence of pus is the most useful method for diagnosis of endometritis. The character and odor of the vaginal mucus can be scored and this endometritis score is correlated with the growth density of pathogenic bacteria in the uterus, and is prognostic for the likely success of treatment. The challenge for the future is to design prevention and control programs to reduce the incidence of disease, and understand how the immune and endocrine systems are integrated.

Association between postpartum pyrexia and uterine bacterial infection in dairy cattle

The temperature of 90 dairy cattle was recorded for the first 10 days after parturition and the animals were categorised as either normal (< 39.7 degreesC) or pyrexic. Swabs were collected from the uterine lumen seven, 14, 21 and 28 days after parturition for aerobic and anaerobic culture; bacteria were identified and their growth was scored semiquantitatively. Blood samples were collected three times a week for the estimation of the concentrations of acute phase proteins. The cows' temperatures were often above the accepted normal range, but it was not a good indicator of the number of bacteria in the uterus. However, pyrexia was correlated with the presence of specific uterine pathogens (P < 0.05) and in particular with Prevotella species (P < 0.01). The pyrexic animals had a higher plasma concentration of the acute phase protein (alpha1-acid glycoprotein (P < 0.05). Although pyrexia is an indicator of postpartum inflammation, additional clinical signs are necessary to identify uterine bacterial infection.

Effect of intrauterine administration of oestradiol on postpartum uterine bacterial infection in cattle

After parturition fewer first dominant follicles are selected in the ovary ipsilateral to the previously gravid uterine horn in cattle. However, the presence of a large oestradiol-secreting follicle in the ipsilateral ovary is a predictor of fertility, possibly due to a localised effect of oestradiol which increases the rate of elimination of the ubiquitous uterine bacterial contamination that occurs after calving. The present study tested the hypothesis that oestradiol reduces uterine bacterial contamination when administered into the uterine lumen around the expected time for selection of the first postpartum dominant follicle. Animals were infused with saline (n=15) or 10mg oestradiol benzoate (n=15) into the previously gravid uterine horn on Days 7 and 10 postpartum. Peripheral coccygeal blood samples were collected daily and oestradiol concentrations measured by radioimmunoassay (RIA). Uterine lumen swabs were collected 7, 14 and 21 days postpartum for aerobic and anaerobic culture, bacteria were identified and growth scored semi-quantitatively. Plasma oestradiol concentrations were higher for treated animals between Days 7 and 14 (1.4+/-0.1 versus 2.0+/-0.2 pg/ml, P<0.05). Control animals had a similar bacterial growth score on Days 7 and 14, with a lower value on Day 21 (5.7+/-1.0 and 6.1+/-0.7 versus 0.3+/-0.1, P<0.05). However, treated animals had a surprising higher bacterial load on Day 14, than on Days 7 or 21 (7.1+/-0.9 versus 4.0+/-0.6 or 3.6+/-0.6, P<0.05). The increased score was attributable to more pathogens associated with endometritis on Day 14 than Day 7 (5.1+/-1.0 versus 2.5+/-0.5, P<0.05), in particular Prevotella melaninogenicus (1.5+/-0.5 versus 0.7+/-0.2, P<0.05) and Fusobacterium necrophorum (1.5+/-0.4 versus 0.3+/-0.2, P<0.05). In conclusion, administration of oestradiol into the uterine lumen surprisingly increased uterine pathogenic anaerobic bacterial contamination. Thus, it is unlikely that increased fertility associated with a first dominant follicle in the ipsilateral ovary is a consequence of the elimination of bacterial contamination by ovarian oestradiol.

Influence of Griseofulvin treatment on semen quality in the dog

Griseofulvin is used to treat dermatomycosis in many species and causes oligospermia in supra-pharmacological doses. The aim of the present study was to evaluate the effect of Griseofulvin administered at therapeutic doses upon semen quality in dogs. Four dogs were treated with Griseofulvin (25 mg/kg per day) for 30 days. Semen collections and analyses were performed before, during and for 100 days after treatment for the Griseofulvin group and 10 untreated control dogs. Semen analyses included mean percentage of forward progressively motile sperm, total sperm output, normal live sperm and normal dead sperm. There was no significant difference between control and treated dogs for each of the semen quality parameters. Therapeutic dosage of Griseofulvin had no deleterious effect upon semen quality in dogs, although this does not preclude potential embryotoxic and teratogenic effects.

The effect of oestradiol on postpartum uterine involution in sheep

The present study tested the hypothesis that ovarian oestradiol increases the rate of uterine involution after parturition in sheep. The day after parturition, ewes were randomly assigned as un-operated controls (n=5), or a 3 cm silastic implant containing oestradiol (n=8) or empty (n=7) was sutured within the bursa of the ovary ipsilateral to the previously gravid uterine horn. Blood samples were collected daily for measurement of PGFM and acute phase proteins until 17 days postpartum when the ewes were slaughtered and the genital tract was collected. There was no consistent effect of treatment group on uterine involution determined by the collagen density, dry matter content, width, length, or weight of the genital tract. Furthermore, there was no evidence of a localised effect of oestradiol on involution as there were no significant differences between the previously gravid and non-gravid uterine horns. However, oestradiol-treated ewes had lower plasma concentrations of 15-keto-13,14-dihydro-prostaglandin F2alpha (P<0.01), alpha1-acid glycoprotein (P<0.05) and ceruloplasmin (P<0.001); but, not haptoglobin. These observations could reflect a direct effect of oestradiol on inflammatory mediator synthesis or secretion because, in the absence of parallel physical measurements, it is unlikely that these observations reflect a beneficial effect of treatment on uterine health.

Reproductive challenges facing the cattle industry at the beginning of the 21st century

The aim of this review is to pinpoint the areas that require further research for greatest impact to improve the efficiency of dairy and beef production. Increased knowledge about the principal causes of reduced fertility is essential. Increases in milk yield have been at the expense of reduced fertility in dairy cows and although diet has a major impact, the precise interaction between nutrition and reproduction still needs to be characterized in both beef and dairy cows. Furthermore, during periods of inadequate nutrition or stress, the intensity of oestrus is reduced by inadequate exposure to oestradiol. However, it is still unclear which pheromones are involved at oestrus, how synthesis is controlled and how pheromones are detected in herd-mates. GnRH may be involved in behaviour but the brain centres that translate hormonal messages are unknown. Attempts to overcome poor oestrous detection include measurements of milk progesterone, telemetric pressure detectors and devices that record the extra activity at oestrus. Substitution of heat detection by 'hormone treatment remedies' has met strong consumer resistance in Europe. The creation of larger cattle units and increased movements world-wide render herds more susceptible to infectious agents, such as Neospora, Leptospira, Trypanosoma and Bovine Viral Diarrhoea virus (BVDv), but it is unclear how other clinical conditions, such as lameness or endometritis, also interfere with ovarian function. The future of dominant follicles selected within 14 days after parturition is crucial--normal ovulation, prolonged persistence or atresia. Calving carries the greatest risk in the reproductive life of a cow and yet little work has focused on reducing the frequency of this event. For dairy cows, a greater understanding about induced or extended lactation is required. For beef animals, precise induction of twinning and nutritional adjustments could produce two offspring per pregnancy. At the start of pregnancy, the trophoblast produces interferon to prevent luteolysis, but the immunological implications are unknown and it is not clear how the rest of pregnancy is maintained. Profiles of pregnancy specific protein B (PSPB) have increased understanding of embryonic death. However, 25% of cows in abattoirs are pregnant, even though 30% of involuntary cullings are 'for failing to conceive'. Clearly, this is an area of wastage that requires urgent resolution. It is unknown why undernutrition at the time of insemination or in early pregnancy leads to delayed births, low fetal weights and later adverse health. At the end of pregnancy, the fetus controls the onset of parturition, but very little is known about the biochemical control of cervical dilation and placental separation. On the male side, bulls are selected for optimal freezability of semen; however, there is as yet no reliable predictor for semen fertility. Methods for accurately pre-determining the sex of both semen and embryos will revolutionize the dairy and beef industries.

Effect of postpartum manual examination of the vagina on uterine bacterial contamination in cows

Twenty-one days after they had calved, the vaginas of 34 cows were examined with a clean gloved hand, and 26 cows were left unexamined. Swabs were collected from the lumen of the uterine body of the cows on the same day and seven days later; bacteria were identified by aerobic and anaerobic culture, and bacterial growth was scored semi-quantitatively. On the same days, blood samples were collected and the concentrations of acute phase proteins were measured, and the diameters of the cows' uterine horns were measured by transrectal ultrasonography. The vaginal examinations did not result in uterine bacterial contamination or an acute phase protein response, and they did not affect the diameters of the uterine horns.

Influence of uterine bacterial contamination after parturition on ovarian dominant follicle selection and follicle growth and function in cattle

First postpartum dominant follicles are preferentially selected in the ovary contralateral to the previously gravid uterine horn. The aim of the present study was to test the hypothesis that uterine bacterial contamination alters the location of ovarian follicle emergence and selection, and inhibits follicle growth and function. Swabs were collected from the uterine body lumen of cattle on days 7, 14, 21 and 28 after parturition. Bacteria were identified by aerobic and anaerobic culture; bacterial growth was scored semiquantitatively and animals were categorized into standard or high bacterial contamination categories on the basis of the number of colonies detected. Follicular growth and function were monitored by daily transrectal ultrasonography, and estimation of plasma FSH, oestradiol and progesterone concentrations. There was no effect of bacterial contamination on plasma FSH concentration profiles or emergence of the ovarian follicle wave. When uterine bacterial growth scores were high on day 7 or day 21 after parturition, fewer first (1/20 versus 15/50; P < 0.05) or second (1/11 versus 13/32; P < 0.05) dominant follicles were selected in the ipsilateral compared with the contralateral ovary, respectively. The diameter of the first dominant follicle was smaller in animals with a high day 7 bacterial score (P < 0.001), dominant follicle growth was slower (P < 0.05) and oestradiol secretion was decreased (P < 0.05). The present study provides evidence for an effect of the uterus on the ovary after parturition, whereby uterine bacteria have a contemporaneous localized effect on ovarian follicle selection and subsequent growth and function, but not on initial emergence.

Influence of uterine bacterial contamination after parturition on ovarian dominant follicle selection and follicle growth and function in cattle

First postpartum dominant follicles are preferentially selected in the ovary contralateral to the previously gravid uterine horn. The aim of the present study was to test the hypothesis that uterine bacterial contamination alters the location of ovarian follicle emergence and selection, and inhibits follicle growth and function. Swabs were collected from the uterine body lumen of cattle on days 7, 14, 21 and 28 after parturition. Bacteria were identified by aerobic and anaerobic culture; bacterial growth was scored semiquantitatively and animals were categorized into standard or high bacterial contamination categories on the basis of the number of colonies detected. Follicular growth and function were monitored by daily transrectal ultrasonography, and estimation of plasma FSH, oestradiol and progesterone concentrations. There was no effect of bacterial contamination on plasma FSH concentration profiles or emergence of the ovarian follicle wave. When uterine bacterial growth scores were high on day 7 or day 21 after parturition, fewer first (1/20 versus 15/50; P < 0.05) or second (1/11 versus 13/32; P < 0.05) dominant follicles were selected in the ipsilateral compared with the contralateral ovary, respectively. The diameter of the first dominant follicle was smaller in animals with a high day 7 bacterial score (P < 0.001), dominant follicle growth was slower (P < 0.05) and oestradiol secretion was decreased (P < 0.05). The present study provides evidence for an effect of the uterus on the ovary after parturition, whereby uterine bacteria have a contemporaneous localized effect on ovarian follicle selection and subsequent growth and function, but not on initial emergence.

Cryopreservation of epididymal dog sperm

A method of cryopreservation was developed for sperm salvaged from the cauda epididymis and vas deferens of domestic dog testes. Four modifications of the glycerol concentration of a buffer used for cryopreservation of dog ejaculates and two freezing rates were assessed for their effect upon post-thaw spermatozoal motility and morphology. There was no statistical difference between the four glycerol concentrations or the two freezing rates and the buffer containing 6% glycerol and the freezing rate provided by 0.5 ml straws was chosen for further study. This method resulted in a significant reduction in the percentage of live spermatozoa detected with Hoechst staining and a reduction in the percentage of capacitated spermatozoa after freeze-thawing. However, there was no difference in the ability of frozen-thawed spermatozoa to penetrate homologous oocytes. This study demonstrates that cryopreservation of epididymal canine sperm can be performed using methods similar to those established for ejaculates of the same species, and that despite some damage, spermatozoa retain their functional ability.

Acute phase protein responses to uterine bacterial contamination in cattle after calving

Repeated ultrasonographic examinations and collections of blood samples and uterine lumenal swabs between seven and 28 days after calving were used to examine the relative effects of bacterial contamination and involution of the uterus on the concentrations of acute phase proteins in the blood of 26 dairy cows. The severity of bacterial contamination, as determined by the total bacterial growth score, was a significant variable for the concentrations of the acute phase proteins alpha1-acid glycoprotein (P < 0.0001), haptoglobin (P < 0.05) and ceruloplasmin (P < 0.0001). In addition, the concentrations of alpha1-acid glycoprotein and ceruloplasmin were increased in the cows from which Escherichia coli (P < 0.0001) and Arcanobacterium pyogenes (P < 0.05), respectively, were isolated from the uterine lumen. Uterine involution, as determined by the decreasing diameter of the previously gravid uterine horn, was associated with a decrease in the concentrations of alpha1-acid glycoprotein (P < 0.005), haptoglobin (P < 0.05) and ceruloplasmin (P < 0.01). However, the response of the acute phase proteins to bacterial contamination was independent of the day on which the samples were collected, indicating that their concentrations were increased by bacterial contamination in addition to the changes associated with uterine involution.