The expression of prostaglandin endoperoxide synthase 2 messenger RNA and the proportion of smooth muscle and collagen in the sheep cervix during the estrous cycle

The use of transcervical artificial insemination in sheep is limited because of the anatomy of the cervix, which restricts the passage of an inseminating pipette into the uterine lumen. There is a degree of natural cervical relaxation at estrus that enables greater penetration with an inseminating pipette. We hypothesize that this relaxation may be regulated by cervical prostaglandin synthesis and remodeling of the cervical extracellular matrix. The present study investigated the changes in prostaglandin endoperoxide synthase 2 (PTGS2) mRNA expression and the proportion of smooth muscle and collagen in the sheep cervix during the estrous cycle. Sheep cervices were collected at four stages of the estrous cycle: prior to the LH surge, during the LH surge, after the LH surge, and during the luteal phase. The expression of cervical PTGS2 mRNA was determined by in situ hybridization, and the proportion of smooth muscle and collagen in the cervix was investigated by Masson trichrome staining. The expression of PTGS2 mRNA in the sheep cervix was greatest prior to the LH surge, when estradiol concentrations were also greatest. The increase in PTGS2 mRNA expression was associated with an increase in the proportion of collagen in the sheep cervix. We propose that prior to the LH surge, estradiol may stimulate PTGS2 mRNA expression and hence prostaglandin E2 synthesis in the sheep cervix to regulate cervical relaxation, most likely through the rearrangement of collagen bundles within the cervical extracellular matrix.     

Effect of site of deposition on the fertility of sheep inseminated with frozen-thawed semen

The widespread use of artificial insemination (AI) in sheep is currently prevented due to the lack of a cost effective insemination technique utilising frozen-thawed semen. The objective of the present study was to determine if the deposition of frozen-thawed semen in the vaginal fornix would result in a pregnancy rate comparable to that achieved following cervical insemination. Multiparous ewes of various breeds were synchronised and inseminated into either the vaginal fornix (n=78) or the cervix (n=79), at 57 h post sponge removal, with frozen-thawed semen. Information on mucus secretion and the depth to which it was possible to penetrate the cervix at insemination (cervically inseminated ewes only) was recorded at the time of AI. Pregnancy rate was subsequently determined either by return to service (oestrus) or after slaughter 30 days post insemination. Insemination site did not significantly influence pregnancy rate using frozen-thawed semen (36.2% compared to 27.6% for cervical and vaginal fornix insemination, respectively; P=0.26). Whilst depth of cervical penetration was positively associated with pregnancy rate (P<0.05), this association needs to be interpreted with caution as none of the ewes where the cervix could not be penetrated (score=0) was pregnant. In conclusion, pregnancy rate following insemination of frozen-thawed semen into the vaginal fornix was within 10% points of that obtained following cervical AI of frozen-thawed semen. As insemination into the vaginal fornix is technically easier than cervical insemination, it may be more practical for use in large scale applications.     

Cervical expression of hyaluronan synthases varies with the stage of the estrous cycle in the ewe

The natural cervical relaxation which occurs at estrus in the ewe may be initiated by binding of hyaluronan (HA) to its receptor CD44. Indeed, we have previously shown that HA content and fragment size in the ovine cervix varies with the stage of the estrous cycle. Despite the importance of cervical relaxation in promoting sperm transport and facilitating the possible development of transcervical artificial insemination (AI), the mechanisms coordinating these changes in HA content remain to be defined. Hyaluronan synthases (HAS) 1, 2, and 3 regulate HA biosynthesis and herein, we describe the changing pattern of HAS isoform expression during the estrous cycle to determine whether this may underpin HA-mediated changes in relaxation of the ovine cervix. Accordingly, cervices were collected from 24 cyclic sheep (n = 8 / group) at the luteal, pre-luteinizing hormone (LH) and post-LH surge stages. Protein and mRNA expression for HAS 1, 2 and 3 was determined in five different tissue layers (epithelium, subepithelial stroma, and longitudinal, circular and transverse muscle) of the vaginal, mid and uterine regions of each cervix by immunohistochemistry and in situ hybridization, respectively. HA synthases were expressed in all the tissue layers and regions of the cervix, and the pattern of expression was similar for mRNA and protein. HAS1 protein and mRNA expression was significantly (P ≤ 0.05) higher at the pre-LH surge stage, while HAS 2 and 3 protein and mRNA expression was significantly (P ≤ 0.001) higher at the luteal stage. Overall, both HAS protein and mRNA expression was significantly (P ≤ 0.001) higher in the epithelial layer and the vaginal region. These findings are in accordance with our previous results and explain the differences observed in the HA content and differing HA fragment size at different stages of the estrous cycle.     

Use of a vaginal mucus impedance meter to detect estrus in the cow

Two experiments were conducted to investigate the efficacy of a vaginal mucus impedance meter for the detection of estrus in the dairy cow. In Experiment 1 the positioning of the probe within the vaginal tract was examined in dairy cows (n=6) by measuring mucus impedance at 5-cm intervals during probe withdrawal and comparing these fixed distance measurements with the depth within the vaginal tract at which the lowest impedance measurement was recorded. Measurements at 15 and 20 cm from the vulva were significantly lower than at other fixed depths, but did not show a reduction during estrus. The lowest recording upon withdrawal of the probe, which usually occurred between 15 and 20 cm from the vulva, was significantly lower than at any fixed depth recordings and was reduced proportionate during estrus to 0.14 of its non-estrus value. In Experiment 2 the accuracy of the probe to confirm estrus in cows exhibiting possible estrus signs was examined. Dairy cows (n=191) were inseminated either on the basis of herdsman observation of behavior alone (Treatment A) or on the basis of herdsman observation with cows exhibiting signs of estrous behaviour, but not standing to be mounted, being tested for vaginal mucus impedance (Treatment B). There were no significant treatment differences in the estrus detection rate, conception rate or other reproductive performance parameters. However, in 12% of cows in Treatment B, measurement of vaginal mucus impedance detected an extra estrous event, giving a theoretical increase in the estrus detection rate from 0.67 to 0.74 detected/predicted estrous events. It was concluded that when using a vaginal probe the lowest value in the vaginal tract should be sought, but that using the probe as an adjunct to herdsman's observation would not greatly increase estrus detection rate.     

A study of two protocols combining aglepristone and cloprostenol to treat open cervix pyometra in the bitch

To compare the efficacy and safety of two protocols using a combination of aglepristone and cloprostenol for the treatment of open cervix pyometra in the bitch and to describe the progesterone (P4) serum profiles before and during treatments, 15 bitches were randomly allocated into two treatment groups: I (n = 8): aglepristone was administered at 10mg/kg, s.c., on Days 1, 3, 8, and 15 (if not cured), combined with cloprostenol at the dose of 1 microg/kg, s.c., on Days 3 and 8, and II (n = 7): received the same treatment with aglepristone as Treatment I but cloprostenol on Days 3, 5, 8 10, 12, and 15 (if not cured). Before the beginning of the treatments and then on Days 8, 15, and 29 all bitches were evaluated for clinical signs, side effects, hemogram, serum P4 concentrations, and uterus diameters. Bitches in both treatment groups, with (n = 6) or without (n = 9; > or =1.2 ng/ml) initial basal P4 serum concentrations, achieved treatment success without side effects and no significant differences, either on Day 15 (6/8 for Treatment I and 4/7 for Treatment II) or on Day 29 (2/8 for Treatment I and 3/7 for Treatment II). In both treatments groups, clinical signs, blood parameters, and uterine diameters improved to normal values throughout the experiments. A significant interaction between day and treatment was found for percentage change in P4 when all bitches were considered together. Redevelopment of pyometra in the next estrous cycle occurred in 20% of the bitches. One nonrecurrent bitch was mated and whelped a normal litter. It is concluded that these two combined protocols proved to be efficient and safe in reversing clinical signs of open cervix pyometra independently of initial P4 concentrations and that the number of cloprostenol administrations seemed to have an effect on P4 serum changes throughout treatments.     

Effect of bromocriptine and progesterone on the length of the ovarian cycle in 4- and 5-day estrous cyclic rats

To study the effect of prolactin and progesterone on the length of the reproductive cycle in the rat, rats of different estrous cycle length (four and five days, respectively) were injected daily (09.00 h) with either bromocriptine (1 mg/rat) or 70% ethanol vehicle (0.25 ml) from the day of estrus onward, up to the appearance of the next ovulation. Each group of rats was then (16.00, metestrus) also injected with either progesterone (4 mg/rat) or 0.2 ml of olive oil. The effects of these treatments on the length of the estrous cycle was studied by both the recording of vaginal smears daily and by direct visualization of oocyte-cumulus complexes on the ensuing day of estrus (10.00 h-12.00 h). Bromocriptine treatment shortened the length of the cycle by one day in 5-day but not in 4-day cyclic rats, while progesterone treatment lengthened estrous cycles by one day in both groups of rats. Treatment with both bromocriptine and progesterone had no effect on the estrous cycle length of 5-day cyclic rats, but did prolong in one day the cycle of 4-day cyclic rats. These facts suggest that prolactin regulates the length of the ovarian reproductive cycle in the rat through its action on the secretion of progesterone by the corpus luteum.     

A technique for transcervical intrauterine insemination of ewes

In commercial artificial insemination (AI) of sheep, fresh extended semen is deposited into the vagina or cervical os, or fresh extended or frozen semen is placed laparoscopically into the uterus. Transcervical intrauterine insemination of the ewe is not used commercially. In this study, methods of restraint and instrumentation for AI were evaluated and modified to produce a transcervical intrauterine technique suitable for commercial application. Four methods of restraint, four vaginal specula, three forceps and four instruments suitable for transcervical passage were compared. From these comparisons a technique was developed in which the ewes were positioned in dorsal recumbency with their hindquarters elevated. The vagina was dilated using a duck-billed speculum, the cervix was grasped and retracted using forceps, and an inseminating instrument was introduced into the cervical opening and manipulated through the cervical canal. The technique was repeated on 89 mature, multiparous ewes: the difficulty in locating the cervical opening, the force required to retract the cervix and the time required to penetrate into the uterus were recorded. Uterine penetration was achieved in 82% of the ewes. This technique has the potential to be applied in commercial artificial insemination programs of sheep.     

Structure-activity relationship study of human interleukin-3: role of the C-terminal region for biological activity.

A structure-activity relationship study of human interleukin-3 (huIL-3) was performed by functional analysis of huIL-3 deletion and substitution variants combined with epitope mapping of huIL-3 specific neutralizing monoclonal antibodies (mAb). Analysis of the huIL-3 variants was accomplished by defining their capacity to compete with wild-type huIL-3 for binding to the huIL-3 receptor and to induce the proliferation of the huIL-3 dependent cell line M-O7. HuIL-3 variants with either 14 amino acids (aa) deleted from the N-terminus or eight aa from the C-terminus retained full biological activity in vitro. An huIL-3 variant, with 18 N-terminal aa deleted, exhibited a greater than 7-fold reduced receptor binding capacity and proliferative activity. No biological activity could be detected with a variant where 22 C-terminal aa have been deleted. Neutralizing mAb recognizing presumed discontinuous epitopes failed to interact with the latter deletion variant indicating a possible location of their epitopes within the C-terminal region. Computer-aided structure prediction and sequence homology analysis of this region indicated the presence of an amphiphilic alpha-helix with highly conserved residues like Lys110 and Leu111. Substitution of Lys110 with either Glu or Ala resulted in variants with a 10-fold reduced activity in the receptor binding assay and the proliferation assay. Further variants, where Leu111 was substituted by Pro or Met, were totally inactive in these assays. Analysis of the binding of the two neutralizing mAb to these substitution variants showed that they did not bind to either of the Leu111 variants suggesting that Leu111 is part of an active site. Based on our results, a possible model for the structure of the huIL-3 molecule can be constructed with two active sites in close proximity.     

Increased cleavage and blastocyst rate in ewes treated with bovine somatotropin 5 days before the end of progestin-based estrous synchronization

Treatment with bovine somatotropin (bST) during estrous synchronization increased fertility and prolificacy in sheep. In the present study, a single dose of bST 5 days before the end of progestin treatment improved cleavage and embryo development. Stage of estrous cycle was synchronized in ewes (n=32) with progestin and superovulation was induced by use of FSH. Five days before the end of progestin treatment, ewes were randomly assigned to two groups: bST group (n=16) received a depot injection of 125 mg of bST sc (Lactotropina, Elanco, México) and the control group (n=16) received saline solution. Estrous was detected with rams fitted with an apron every 2 h and estrous sheep were mated every 8 h whilst in estrous. Embryos were recovered on Day 7 post mating, assessed microscopically and fixed in 4% paraformaldehyde. Cell number in blastocysts was counted after Hoechst 33342 staining. Plasma concentrations of IGF-I, insulin and progesterone were determined in eight sheep per group from the day of bST treatment to the day of embryo recovery. Cleavage rate, percentage of transferable embryos (transferable embryos/cleaved) and percentage of embryos reaching the blastocyst stage (blastocyst/cleaved) were compared between groups by logistic regression. IGF-I, insulin and progesterone plasma concentrations were analyzed by ANOVA for repeated measurements and cell number by ANOVA. Cleavage rate was greater (P<0.01) in bST treatment group (86%) than in the control group (62%). Similarly, the proportion of embryos reaching the blastocyst stage (bST=68.7 vs control=42.5) and the number of cells per blastocyst (bST group 91.8±5.5 compared to control group 75±6) were greater (P<0.01) in the bST-treated sheep. Plasma concentrations of IGF-I and insulin were greater (P<0.01) in the bST-treated group. No changes were observed in progesterone concentrations (P=0.5). It is concluded that bST injection 5 days before progestin removal increases cleavage rate and the proportion of embryos that reach the blastocyst stage. These effects are associated with an increase in IGF-I and insulin concentrations.     

Investigations on spermicidal activity in the sheep vagina.

This study was conducted to elucidate some of the effects of a synthetic progestagen and natural ovarian hormones on spermicidal activity in the sheep vagina. In the first experiment, parous ewes were treated for 17 days either intravaginally with medroxyprogesterone acetate (MAP) or subcutaneously with progesterone. They were inseminated artificially either on the last day of progestagen treatment or during estrus after progestagen withdrawal. Their vulvovaginal junctions were ligated to prevent the loss of sperm cells by drainage to the exterior. Untreated control ewes were inseminated during either estrus or the luteal phase of the estrous cycle. The ewes were killed 22 hr. after insemination, their vaginas flushed, and intact sperm cells and tailless sperm heads counted. In the second and third experiments, some of the ewes were bilaterally ovariectomized and inseminated several weeks later. Other ewes were ovariectomized and given subcutaneous injections of estradiol, progesterone, or both hormones.In the first experiment, most sperm cells were recovered intact from estrous or luteal phase control ewes. The intravaginal administration of MAP increased both the breakage of sperm cells into heads and tails and the disappearance of sperm cells. The spermicidal effects of MAP were just as great in ewes inseminated on the last day of treatment. as in those inseminated during the ensuing estrus; these results indicated that the peak estrogen secretion that occurs near the beginning of estrus was not necessary for the intensification of spermicidal activity.In the second experiment, ovariectomized ewes were compared to estrous and luteal phase ewes in regard to vaginal spermicidal activity. Sperm breakage and disappearance occurred least in estrous ewes, to a somewhat greater degree in luteal phase ewes, and to the greatest extent in ovariectomized ewes. The results suggested that endogenous ovarian hormones, particularly those in estrous ewes, suppress spermicidal mechanisms in the vagina.In the third experiment, the administration of estradiol and progesterone to ovariectomized ewes prevented the increase in sperm cell disappearance. Neither hormone alone prevented the increase.     

A single dose of bovine somatotropin 5 days before the end of progestin-based estrous synchronization increases prolificacy in sheep

Bovine somatotropin (bST) enhances ovarian follicular and embryonic development in sheep and cattle. In the present study, the objective was to assess whether bST given 5 days before the end of progestin-based estrous synchronization improves prolificacy and lambing rate in sheep. Pelibuey ewes (n=92) exhibiting estrous cycles at regular intervals received an intravaginal sponge containing 45mg of FGA for 12 days. Five days before sponge withdrawal, ewes were treated with either 125mg of bST sc (bST group; n=47) or saline solution (control; n=45). After the sponge was removed, ewes were observed for estrus and subsequently mated twice. Lambing rate and prolificacy was determined at birth. Blood samples were taken from the time of treatment until day 15 after estrus in eight ewes from the bST group and nine from the control group. Concentrations of IGF-I were determined by immunoradiometric assay and progesterone by RIA. Treatment with bST increased (P<0.01) the proportion of ewes with more than one lamb (bST, 56% compared with control, 26%) and prolificacy (bST, 1.6 compared with control, 1.3). Treatment with bST increased (P<0.05) the lambing rate of multiparous (bST, 92% compared with control, 67%) but not in ewes at the first time they were mated (bST, 71% compared with control, 87%; P>0.05). IGF-I concentrations were greater (P<0.01) in ewes treated with bST than in control ewes from 2 days after treatment. Progesterone concentrations did not vary (P>0.05) between groups. It is concluded that a single dose of bST 5 days before progestin withdrawal increases lambing rate and prolificacy in sheep. These effects are associated with an increase in circulating concentrations of IGF-I.     

Distribution of estrogen receptor alpha and progesterone receptor, and leukocyte infiltration in the cervix of cyclic bitches and those with pyometra

The objectives were to localize estrogen receptor alpha (ERα) and progesterone receptor (PR), and enumerate leukocyte infiltration in cervical tissue of normal bitches during various stages of the estrous cycle (n = 35), as well as in those developing open (n = 22) or closed-cervix pyometra (n = 19). Each pyometra group was subdivided into anestrus and diestrus. Cervical tissues were collected after ovariohysterectomy. Receptor expressions were determined by immunohistochemistry and leukocyte infiltration was evaluated in histological sections stained with haematoxylin-eosin. The assessment was performed in two parts of cervical sections: the uterine part in four tissue layers (surface epithelium (SE), lamina propria (LP), glandular epithelium (GE), and tunica muscularis (M)), and the vaginal part in three layers (SE, LP and M). An immunohistochemical total score consisted of the addition of both the intensity and proportional scores. The ERα and PR scores differed between groups (P < 0.05) and between layers (P < 0.05), but were not significantly different between uterine and vaginal parts. The ERα score was lowest in the open-cervix pyometra bitches at anestrus and in closed-cervix pyometra bitches at diestrus. For all types of immune cells, there were no significant differences among stages of the estrous cycle in normal bitches, whereas neutrophils were lower in both sub-groups of closed-cervix versus open-cervix pyometra (P < 0.05). In conclusion, distributions of ERα and PR were similar along the longitudinal axis of the canine cervix. We inferred that cervical dilation in normal bitches and bitches with uterine pathology was likely controlled by different mechanisms. Receptor expressions were influenced by stage of the estrous cycle in normal bitches, whereas neutrophil infiltration in cervical tissue appeared to be involved in cervical dilation in bitches with pyometra, regardless of estrous stages.     

Clenbuterol (planipart(trade mark)) for the postponement of parturition in cattle

Clenbuterol is a highly specific, long-acting (four to eight hours) beta-two sympathomimetic which causes bronchodilation and tocolysis (myometrial paralysis). The tocolytic effect was explored as a means to control parturition and reduce dystocia. Forty-six heifers were injected i.m. with either Clenbuterol or saline placebo in a randomly controlled experiment. Animals were treated when a cervical dilation of five centimeters or more was detected by vaginal examination. Length of first, second and third stages of parturition, ease of parturition, maternal pelvic area and calf viability were compared between treatment groups. Treatment with Clenbuterol increased (P<0.025; 119 vs 468 mins) the time heifers were in Stage I. However, the lengths of Stages II and III, pelvic area at birth and calf viability were not influenced by treatment. Diameter of the cervix at treatment was negatively related to the length of Stage I delay. Pelvic area also significantly affected the length of Stage II. Clenbuterol effectively delays Stage I of parturition with no adverse effects on the fetus or dam.     

Decreased neutrophil adhesion to human cytomegalovirus-infected retinal pigment epithelial cells is mediated by virus-induced up-regulation of Fas ligand independent of neutrophil apoptosis

Human CMV (HCMV) retinitis frequently leads to blindness in iatrogenically immunosuppressed patients and in the end stage of AIDS. Despite the general proinflammatory potential of HCMV, virus infection is associated with a rather mild cellular inflammatory response in the retina. To investigate this phenomenon, the influence of HCMV (strains AD169 or Hi91) infection on C-X-C chemokine secretion, ICAM-1 expression, and neutrophil recruitment in cultured human retinal pigment epithelial (RPE) cells was studied. Supernatants from infected cultures contained enhanced levels of IL-8 and melanoma growth-stimulating activity/Gro alpha and induced neutrophil chemotaxis compared with supernatants from uninfected RPE cells. Despite HCMV-induced ICAM-1 expression on RPE cells, binding of activated neutrophils to HCMV-infected RPE cells and subsequent transepithelial penetration were significantly reduced. Reduced neutrophil adhesion to infected RPE cells correlated with HCMV-induced up-regulation of constitutive Fas ligand (FasL) expression. Functional blocking of FasL on RPE cells with the neutralizing mAbs NOK-1 and NOK-2 or of the Fas receptor on neutrophils with mAbB-D29 prevented the HCMV-induced impairment of neutrophil/RPE interactions. Fas-FasL-dependent impairment of neutrophil binding had occurred by 10 min after neutrophil/RPE coculture without apoptotic signs. Neutrophil apoptosis was first detected after 4 h. Treatment of neutrophils with a specific inhibitor of caspase-8 suppressed apoptosis, whereas it did not prevent impaired neutrophil binding to infected RPE. The current results suggest a novel role for FasL in the RPE regulation of neutrophil binding. This may be an important feature of virus escape mechanisms and for sustaining the immune-privileged character of the retina during HCMV ocular infection.     

Papanicolaou staining of exfoliated vaginal epithelial cells facilitates the prediction of ovulation in the giant panda

The giant panda is seasonally monoestrus, experiencing a single estrous with spontaneous ovulation in the spring. Therefore, accurate monitoring of the estrous cycle to pinpoint the time of ovulation is critical for the success of timed mating or artificial insemination. Analysis of exfoliated vaginal epithelial cells is a simple technique that rapidly yields information about the estrous status of a panda. Vaginal swabs were obtained during five estrous cycles of two nulliparous females. Cells were stained with the trichrome Papanicolaou and classified as basophils, intermediates or superficials. The color of stained cells, basophilic, acidophilic or keratinized, was recorded as a characteristic independent of the three standard cell types. The day urinary conjugates of estrogen fell from peak levels was considered the day of ovulation. A chromic shift occurred 8-9 days before ovulation when the majority of exfoliated vaginal cells changed from basophilic (blue) to acidophilic (pink) without accompanying nuclear or cytoplasmic changes. A second chromic shift was consistently observed 2 days prior to ovulation when keratinized (orange) cells replaced acidophils as the majority of vaginal cells. Monochrome staining of vaginal cells is sufficient to quantify superficial cells, which is a useful adjunct to behavioral and endocrinological data in determining estrous in the giant panda. However, the timing and duration of superficial cell elevations are substantially different between and within individual females, which limits the accuracy of timing ovulation for artificial insemination. The predictive value of vaginal cytology was greatly enhanced with the trichrome stain and evaluation of cell color.     

Neutrophils are a key component of the antitumor efficacy of topical chemotherapy with ingenol-3-angelate

Harnessing neutrophils for the eradication of cancer cells remains an attractive but still controversial notion. In this study, we provide evidence that neutrophils are required to prevent relapse of skin tumors following topical treatment with a new anticancer agent, ingenol-3-angelate (PEP005). Topical PEP005 treatment induces primary necrosis of tumor cells, potently activates protein kinase C, and was associated with an acute T cell-independent inflammatory response characterized by a pronounced neutrophil infiltrate. In Foxn1(nu) mice depleted of neutrophils and in CD18-deficient mice (in which neutrophil extravasation is severely impaired) PEP005 treatment was associated with a >70% increase in tumor relapse rates. NK cell or monocyte/macrophage deficiency had no effect on relapse rates. Both in vitro and in mice, PEP005 induced MIP-2/IL-8, TNF-alpha, and IL-1beta, all mediators of neutrophil recruitment and activation. In vitro, PEP005 activated human endothelial cells resulting in neutrophil adhesion and also induced human neutrophils to generate tumoricidal-reactive oxygen intermediates. Treatment of tumors with PEP005 significantly elevated the level of anticancer Abs, which were able to promote neutrophil-mediated Ab-dependent cellular cytotoxicity (ADCC) in vitro. PEP005 treatment of tumors grown in SCID mice was also associated with >70% increase in tumor relapse rates. Taken together, these data suggest a central role for neutrophil-mediated ADCC in preventing relapse. PEP005-mediated cure of tumors therefore appears to involve initial chemoablation followed by a neutrophil-dependent ADCC-mediated eradication of residual disease, illustrating that neutrophils can be induced to mediate important anticancer activity with specific chemotherapeutic agents.     

The relationship between vaginal mucous impedance and serum concentrations of estradiol and progesterone throughout the sheep estrous cycle

The objective of this experiment was to assess the relationship between electrical resistance of the vaginal mucosa and serum concentrations of estradiol (E2) and progesterone (P4) during the estrous cycle in ewes. Vaginal impedance was recorded daily using a 2-electrode impedometer in 10 nonprolific Western white-faced and 7 prolific Finn ewes, during the mid-breeding season (October to December). Transrectal ultrasonography of ovaries was performed once a day to confirm ovulation and monitor follicle growth (follicles > or =3 mm in diameter) and development of corpora lutea (CL). Jugular blood samples were collected daily for radioimmunoassay (RIA) of estradiol and progesterone. In all ewes, a decline in vaginal impedance (to <40 ohms) was closely associated with the onset of behavioral estrus. In both breeds of sheep, there was no significant correlation between daily serum concentrations of estradiol and vaginal impedance throughout the estrous cycle. Daily serum concentrations of progesterone and the E2:P4 ratio were correlated with vaginal impedance during the period of luteolysis and follicular phase in both breeds (Western white-faced ewes: r = 0.62, P = 0.0002 and r = -0.56, P = 0.0002; Finn ewes: r = 0.61, P = 0.001 and r = -0.45, P = 0.03, respectively) and early in the cycle (Days 0 to 2, Day 0 = day of ovulation) in white-faced ewes (r = 0.61, P = 0.0003 and r = -0.36, P = 0.052, respectively) but not during the remaining portion of the luteal phase in either breed. In conclusion, vaginal mucous impedance appears to be primarily controlled by progesterone, but it also changes in response to shifts in the E2:P4 ratio when progesterone concentrations are low. Impedometric characteristics of the vaginal mucosa in cyclic ewes are an indicator of serum concentrations of progesterone and E2:P4 ratios during the terminal stage of the estrous cycle.     

A physiological function for apolipoprotein(a): a natural regulator of the inflammatory response

Structural similarities between apolipoprotein(a) (apo(a)), the unique apoprotein of lipoprotein(a), and plasminogen, the zymogen of plasmin, can interfere with functions of plasmin (ogen) in vitro. The purpose of this study was to evaluate the role of apo(a) in inflammation in vivo using apo(a) transgenic mice and to determine if effects are plasminogen-dependent using backgrounds that are either plasminogen-replete or plasminogen-deficient. After administration of peritoneal inflammatory stimuli, thioglycollate, bioimplants or lipopolysaccharide, the number of responding peritoneal neutrophils and macrophages were quantified. Apo(a), in either wild-type or plasminogen deficient backgrounds, inhibited neutrophil recruitment but had no effect on plasminogen-dependent macrophage recruitment. Macrophage-inflammatory protein-2, a neutrophil chemokine, was reduced in apo(a) mice, and injection of this chemokine prior to thioglycollate restored neutrophil recruitment in apo(a) transgenic mice. In the lipopolysaccharide model, mice with apo(a), unlike mice without apo(a), did not increase neutrophil recruitment in response to the stimulus. In the bioimplant model, neutrophil recruitment and neutrophil cytokines were reduced in apo(a)tg mice but only in a plasminogen-deficient background. These results indicate for the first time that apo(a), independent of plasminogen interaction, inhibits neutrophil recruitment in vivo in diverse peritoneal inflammatory models. Hence, apo(a) may function as a cell specific suppressor of the inflammatory response.     

Intrauterine infusion of prostaglandin E2 and subsequent luteal function in cattle.

The objective was to evaluate the effect of intrauterine infusion of prostaglandin E2 (PGE2) on luteal function in cattle. Heifers and cows were randomly assigned after two normal estrous cycles to either PGE2 or control treatment groups. Females in Treatment A were infused with 1 mg of PGE2 once daily into the uterine horn ipsilateral to the corpus luteum between days 7-10 of the estrous cycle with a 0.25 ml plastic semen straw and an artificial insemination pipette. Females in Treatment B were similarly infused with 1 mg of PGE2 once daily in 20 ml of a carrier vehicle via a catheter on days 10 and 11 of the estrous cycle. Control animals were infused with the carrier vehicle using either a semen straw (Treatment C) or via a catheter (Treatment D) on the same days of the estrous cycle. Blood samples were collected daily to monitor plasma progesterone concentrations during the treatment period. Females infused with PGE2 on days 7-10 of the estrous cycle returned to estrus in a mean of 23.5 days (range 22-25 days) and were similar (P > 0.05) to those infused on days 10 and 11 which returned to estrus in 23.5 days (range 22-25 days). Animals similarly infused with carrier vehicle on the same days of the estrous cycle returned to standing estrus in 20.2 days (range 17-23 days). Plasma progesterone concentrations indicated an extended period of elevated progesterone concentrations in PGE2-treated animals compared with control animals. These results indicate that short term administration of PGE2 early in the estrous cycle may result in extended luteal maintenance.