Biomedical subjects

C Aurich

Publications and source records attributed to C Aurich.

31 records · Page 2Linked to original sources

PubMed2001

Lectin binding patterns of uterine glands in mares with chronic endometrial degeneration.

OBJECTIVE: To evaluate changes of glycoconjugate in uterine glands of endometrial tissues obtained from mares. ANIMALS: adult mares. PROCEDURE: Uterine biopsy samples were collected during the breeding season and analyzed histologically for signs of chronic endometrial degeneration. Stage of the estrous cycle was established, using clinical examination and determination of hormonal status. Uterine tissue samples were analyzed, using lectin histochemical and immunohistochemical techniques (estrogen and progesterone receptors). Connective tissues were stained to determine alterations of ground substance in periglandular fibrosis. RESULTS: Of 50 mares, 30 (60%) were classified as normal or having modest alterations, and 20 (40%) were classified as having moderate or severe endometrial degeneration. In normal equine endometrium, several lectins (Helix pomatia agglutinin, Lotus tetragonolobus agglutinin, Ricinus communis I agglutinin, Ulex europaeus agglutinin, and wheat germ agglutinin) bound to glycoconjugates of the luminal epithelium and openings of uterine glands. Lectin binding patterns of cystic dilated glands or fibrotic glands in endometrial samples were remarkably strong, whereas normal surrounding cells remained unstained. Lotus tetragonolobus lectin was not suitable for detecting endometrial alterations. Connective tissues stained with Alcian blue and results of Hale colloidal-iron binding revealed acidic ground substance in periglandular fibrosis. Estrogen and progesterone receptors were evenly distributed in healthy and affected endometrial samples. CONCLUSIONS AND CLINICAL RELEVANCE: Glycoconjugate patterns of uterine glands were altered in mares with chronic endometrial degeneration. Therefore, uterine secretions are likely to be altered. These changes are not induced by changes in content of estrogen and progesterone receptors in endometrial tissues.

Animals↗

PubMed2001

Association of endometriosis in horses with differentiation of periglandular myofibroblasts and changes of extracellular matrix proteins.

Periglandular fibrosis and cystic dilation of uterine glands are associated with equine endometriosis. The presence of extracellular matrix proteins (collagen type I, III and IV, laminin and fibronectin) in healthy and endometriotic specimens was demonstrated by immunohistochemistry. The distribution of collagen I, but not collagen III, was dependent on the stage of the oestrous cycle. The arrangement of collagen I and collagen III in endometriotic specimens was similar to that in normal endometrium. In periglandular fibrosis, collagen IV, laminin and fibronectin deposition outside the basement membrane was observed. In these regions, stromal cells were characterized immunohistochemically as myofibroblasts because of their expression of a-smooth muscle actin, and occasionally tropomyosin and desmin. Periglandular differentiation of contractile cells could be interpreted as a reaction to support the extrusion of secretions in cystic dilated glands. Moreover, the changes of extracellular matrix proteins are characteristic for neoplastic lesions, although further development of endometriosis to benign or malignant tumours is not known in horses. Knowledge of the factors responsible for these fibroblastic modulations may be the key to explaining the pathogenesis of endometriosis.

Animals↗

PubMed1999

Seasonal variation and opioidergic regulation of growth hormone release in cyclic, ovariectomized, and pregnant pony mares.

Modulation of reproductive functions is one of the multiple effects of growth hormone (GH). To investigate effects of reproductive functions on GH release in the horse, plasma GH concentrations in ovary-intact (n = 7) and ovariectomized (n = 8) mares during the anovulatory and breeding seasons and in pregnant mares (n = 6) at various stages of gestation were determined. To analyze an opioidergic regulation of GH release, repeated blood samples were taken over 3 h, and mares were injected with the opioid antagonist naloxone (0.5 mg/kg i.v.) or saline. GH was determined by RIA with an antiserum raised against porcine GH and equine GH as standard. In ovariectomized and ovary-intact, cyclic mares, GH concentrations were low and not different between the two groups in November and December. GH concentrations increased significantly (P < 0.05) in cyclic mares during May and June but were not affected by stage of the cycle and were low in ovariectomized mares. In pregnant mares, plasma GH concentrations remained high throughout pregnancy and did not decrease during winter but increased significantly (P < 0.05) postpartum. Naloxone induced a significant GH release in ovary-intact mares; this response was most pronounced (P < 0.05) during the breeding season. Naloxone did not affect GH in ovariectomized mares. During pregnancy, naloxone induced a significant release of GH around Day 280 (P < 0.05) but not at other times of pregnancy. In conclusion, GH release is influenced by season. The seasonal changes depend on ovarian factors, are absent in ovariectomized mares, and can be modulated by pregnancy. GH release is regulated at least in part by opioidergic pathways.

Animals↗

PubMed1999

[Therapeutic and prophylactic effect of LH-release in cattle].

In this study, LH release in response to the GnRH agonist buserelin and during treatment with a progesterone-releasing intravaginal device (PRID) was studied. A dose of 20 micrograms buserelin induced a more pronounced LH release than 4, 8, 40 and 80 micrograms. After injection of buserelin, pituitary response to a second buserelin injection was markedly reduced for at least 24 hours. Repeated buserelin injections at an interval of several hours therefore cannot be recommended. LH release was markedly suppressed by treatment with PRID. Two PRID tended to be more effective than one. After PRID removal, LH release increased significantly.

Administration, Intravaginal↗

PubMed1999

[Does education prevent dementia?].

PURPOSE: The association of education and the risk of developing dementia are reviewed. Proposed underlying mechanisms are discussed with the particular reference to social aspects. METHODS: The discussion is based on recent work published on the association of education and dementia risk dealing with incident cases. RESULTS: Strength and consistency of the association as well as the partly established dose response relationship indicate that higher education is associated with a lower risk of developing dementia. This had been explained as a consequence of a greater "brain reserve capacity", which might be constituted by different mechanisms in early periods of CNS-development and during adulthood. CONCLUSIONS: Education rather compensates neuro-degenerative changes than protects from dementia. Clinical signs of dementia will be delayed but not prevented. The knowledge about social aspects of this process implies the search for interventions.

Achievement↗

PubMed1997

Effects of antioxidants on motility and membrane integrity of chilled-stored stallion semen.

The use of chilled-stored stallion semen is limited by its relatively short-term fertilizing capacity. An important reason for the decrease in fertility during storage is the peroxidation of sperm membrane lipids. In this study, effects of the antioxidants ascorbic acid (0.45 and 0.9 g/L) and catalase (0.45 x 10(6) and 1.8 x 10(6) units/L) on chilled-stored stallion semen were investigated. Semen was collected by artificial vagina from 7 stallions and was diluted with skim milk extender or glycin extender. Sperm motility and membrane integrity were investigated after dilution and after 24, 48 and 72 h at 5 degrees C. Ascorbic acid significantly increased the percentage of membrane-intact spermatozoa at 24, 48 and 72 h at 5 degrees C when compared with that of the controls (P < 0.05), irrespective of the extender. Ascorbic acid decreased the percentage of progressively motile spermatozoa (P < 0.05) at a concentration of 0.9 g/L in glycin extender. Catalase decreased (P < 0.05) progressively motile spermatozoa after 24, 48 and 72 h at 5 degrees C in skim milk extender at a concentration of 1.8 x 10(6) units/L. Catalase decreased (P < 0.05) the percentage of membrane-intact spermatozoa at 24 h. Motility and membrane integrity of spermatozoa after dilution with glycin extender containing catalase did not differ from the controls. In conclusion, ascorbic acid has protective effects on sperm membrane integrity in diluted stallion semen.

Journal Article↗

PubMed1997

Influence of melatonin and oestradiol on the opioidergic regulation of LH and prolactin release in pony mares.

The aim of this study was to investigate the influence of oestradiol, melatonin and season on the opioid regulation of LH and prolactin release. Effects of the opioid antagonist naloxone (0.5 mg/kg) on LH and prolactin secretion were determined in ovariectomized pony mares. In experiment 1, mares in January (n = 6) were pretreated with oestradiol benzoate (5 micrograms/kg) for 20 days. In experiment 2, beginning in May, mares (n = 7) received melatonin (15 mg) for 15 days and subsequently a combination of melatonin plus oestradiol for 20 days. In experiment 3, beginning in May, mares (n = 6) were pretreated with oestradiol for 30 days, left untreated for 12 days and then given melatonin for 35 days. In all experiments the animals were injected with the opioid antagonist naloxone and saline on 2 consecutive days prior to treatment. In experiment 1, animals received naloxone and saline on days 10 and 11 and 20 and 21 following oestradiol treatment. In experiment 2, naloxone and saline were administered on days 15 and 16 following melatonin treatment and on days 10 and 11 and 20 and 21 of melatonin plus oestradiol treatment. In experiment 3, the animals received naloxone and saline on days 10 and 11, 20 and 21 and 30 and 31 of oestradiol treatment, prior to melatonin treatment and on days 15 and 16, 25 and 26 and 35 and 36 following melatonin. In January (experiment 1), naloxone evoked a significant (P < 0.05) LH release at all times, however the LH increment in response to naloxone increased during oestradiol pretreatment (P < 0.05). During the breeding season (experiments 2 and 3), naloxone induced a significant (P < 0.05) increase in plasma LH concentrations when mares had not been pretreated with oestradiol or melatonin and after oestradiol pretreatment. Basal LH concentrations and the LH increment in response to naloxone increased significantly (P < 0.05) during the 30-day oestradiol pretreatment. Melatonin decreased the naloxone-induced LH release and the LH release in response to naloxone and saline no longer differed after 25 and 35 days of melatonin pretreatment. When melatonin was given together with oestradiol for 20 days, again a significant (P < 0.05) LH release in response to naloxone occurred. Prolactin release was significantly (P < 0.05) increased by naloxone when mares had been pretreated with only melatonin. The opioid antagonist did not affect prolactin release in mares that had not been pretreated or received oestradiol either alone or in combination with melatonin. In conclusion, in long-term ovariectomized mares, opioids inhibit LH secretion independent from ovarian factors. This opioid inhibition of LH secretion is enhanced by oestradiol and reduced by melatonin. Although short-term melatonin treatment inactivates the opioid regulation of LH release, a prolonged influence of melatonin as occurs in winter does not prevent activation of the opioid system. This indicates that effects of melatonin on the opioid regulation of LH release change with time. An opioid inhibition of prolactin secretion is activated by melatonin given for 15-35 days but is lost under the prolonged influence of a short-day melatonin signal in winter.

Animals↗

PubMed1996

Seminal plasma affects membrane integrity and motility of equine spermatozoa after cryopreservation.

Effects of seminal plasma on post-thaw motility and membrane integrity of cryopreserved horse spermatozoa were investigated. Carboxyfluorescein diacetate staining was used for the assessment of sperm membrane integrity. Adding 30% of seminal plasma from stallions with high post-thaw sperm motility to ejaculates from stallions with low post-thaw sperm motility increased progressive motility from 24.0 +/- 1.6 to 34.5 +/- 1.9% (P < 0.05) and membrane integrity from 27.0 +/- 2.1 to 34.3 +/- 2.3% membrane-intact spermatozoa (P < 0.05). Conversely, the addition of seminal plasma from stallions with low post-thaw sperm motility to ejaculates from stallions with high post-thaw motility decreased progressive motility from 36.0 +/- 1.6 to 30.0 +/- 2.7% (P < 0.05) but did not induce changes in membrane integrity. Seminal plasma from stallions with opposite post-thaw motility therefore clearly influenced the resistance of spermatozoa to the freezing and thawing process. We conclude that the individual composition of seminal plasma affects the suitability of stallions for semen cryopreservation.

Journal Article↗

PubMed1995

Effects of gonadal steroids on the opioid regulation of LH and prolactin release in ovariectomized pony mares.

The aim of the present study was to investigate the role of ovarian steroids in the opioid regulation of LH and prolactin release in mares. Effects of the opioid antagonist naloxone on LH and prolactin secretion were determined in ovariectomized pony mares. The animals were pretreated with either progesterone (500 micrograms kg-1) or oestradiol benzoate (10 micrograms kg-1) for 8 days and subsequently with a combination of progesterone and oestradiol for an additional 8 days. Naloxone administration (0.5 mg kg-1 i.v.) resulted in a significant release of LH as well as prolactin in mares after pretreatment with either oestradiol benzoate or progesterone plus oestradiol benzoate (P < 0.05). No significant changes in LH and prolactin secretion were detected in progesterone-treated and non-steroid-treated ovariectomized mares. These results indicate that a prolonged oestrogen influence activates the opioid inhibition of LH and prolactin release in mares. In contrast to other species, progesterone alone does not activate a tonic opioid inhibition of LH and prolactin secretion, but modulates the effect of oestrogens. The opioid systems therefore seem to be regulated by a sequence of different steroid environments, as found during the oestrous cycle. The parallel increases in prolactin and LH secretion in mares may indicate a common regulatory pathway for these two hormones.

Animals↗

PubMed1994

Detection of the homozygous recessive genotype for deficiency of uridine monophosphate synthase by DNA typing among bovine embryos produced in vitro.

A PCR-based DNA test for the genetic defect resulting in the deficiency of uridine monophosphate synthase (DUMPS) was developed for embryonic cells to identify the homozygous recessive genotype. This genotype is usually lethal at about day 40 of gestation. Oocytes from a cow, heterozygous for DUMPS, were fertilized in vitro with spermatozoa from a DUMPS-carrier bull and cultured in vitro until the morula or blastocyst stage. Embryos were matured in vitro, fertilized and cultured according to a method established in our laboratory. Heminested PCR was performed and the genotype of twelve embryos were unambiguously determined by the Aval digestion of the PCR products. Among these embryos two individuals homozygous for the defective DUMPS allele (R405-->STOP) were detected. From the remaining ten embryos, four were homozygous and six were heterozygous for the normal allele. The observed distribution is close to the expected ratio of 1:2:1. These results further support the monogenic recessive inheritance of the defect.

Animals↗

PubMed1994

Involvement of endogenous opioids in the regulation of LH and testosterone release in the male horse.

To investigate the involvement of endogenous opioids in the regulation of gonadotrophin release in male horses, effects of the opioid antagonist naloxone (0.5 mg kg-1 i.v.) on plasma LH and testosterone concentrations and the possible influence of season and of gonadal steroids were investigated. To determine quantitative as well as qualitative changes in gonadotrophin release, LH concentrations were measured by radioimmunoassay and by an in vitro bioassay. Experiments were performed in May, August and December. In stallions, basal LH secretion in May and August was significantly higher than in December (May versus December: P < 0.01; August versus December: P < 0.05); plasma testosterone concentrations were highest in August (August versus May: P < 0.05, August versus December: P < 0.001). The basal bioactive LH concentration and the ratio of bioactive:immunoreactive LH in stallions were highest in May. Therefore, in addition to seasonal changes in quantitative LH secretion, the bioactivity of LH in the circulation also undergoes seasonal variations. Bioactive LH concentrations and the bioactive:immunoreactive ratio in geldings were higher than in stallions. Naloxone caused a significant increase in LH release in stallions in August and December (P < 0.001); no significant increase was found in May (P = 0.06). In geldings, naloxone did not induce any changes in LH secretion; in stallions, a highly significant correlation was observed between basal testosterone concentrations and the LH increment after injection of naloxone (P < 0.001). In August and December, the bioactive:immunoreactive ratio increased significantly (P < 0.05) after injection of naloxone in stallions, indicating a preferential release of LH molecules with high bioactivity. The bioactive:immunoreactive ratio did not change after naloxone injection in May. The naloxone-induced LH release was followed by a significant increase in plasma testosterone concentrations in stallions in August (P < 0.001) and December (P < 0.05). In conclusion, endogenous opioid systems are involved in the regulation of LH and testosterone secretion in stallions. These mechanisms undergo seasonal changes: their activity is increased during winter and decreased during the breeding season. By affecting LH release, endogenous opioids, at least in part, regulate seasonal changes in reproductive activity in the stallion.

Animals↗

PubMed1994

Effects of the opioid antagonist naloxone on release of luteinizing hormone in mares during the anovulatory season.

To investigate an involvement of endogenous opioids in the regulation of circannual changes in reproductive activity, effects of the opioid antagonist naloxone on the concentration of immunoreactive and bioactive luteinizing hormone (LH) in plasma were measured in mares during the anovulatory season. Naloxone (0.5 mg/kg i.v.) caused a significant increase (P < 0.05) in immunoreactive as well as bioactive LH concentration in plasma. The amplitude of the increase in LH concentrations measured with an in vitro bioassay was more pronounced than the amplitude of the increase in LH secretion determined by radioimmunoassay. This indicates that although in seasonal anovulatory mares the bioactivity of LH in plasma is low, highly bioactive LH is present in the anterior pituitary and can be released by naloxone. The LH response to naloxone did not depend on the degree of ovarian follicular activity. It can be concluded that a tonic opioid inhibition of LH release is present in mares during at least part of the anovulatory season and that endogenous opioids seem to be involved in the regulation of seasonal reproductive activity in the horse. In contrast to the situation during the breeding season, the opioid systems regulating LH release are activated independently of luteal progesterone.

Animals↗

PubMed1993

Naloxone affects gastrointestinal functions and behaviour in horses.

Clinical effects of the opioid antagonist naloxone were investigated in healthy horses. Naloxone caused a transient increase in the frequency of defecations, a softening of the faeces and alterations in the intensity of abdominal borborygmi. Total serum protein concentrations decreased. Behavioural changes like frequent yawning and flehmen occurred, heart rate decreased and respiratory rate tended to increase but no clinical signs of distress or pain were observed. It can be concluded that in healthy animals naloxone had only minor side-effects and could be used to investigate the physiological functions of endogenous opioids in horses.

Animals↗