Effects of Short-term Hyper- and Hypoprolactinaemia on Hormones of the Pituitary, Gonad and -Thyroid Axis and on Semen Quality in Male Beagles

Effects of a short-term hyper- and hypoprolactinaemia on serum concentrations of LH, testosterone and semen quality in six male Beagles were investigated. Blood samples were collected at 3-day intervals for 12 weeks. The time span was divided into five 3-week periods: pre-treatment, metoclopramide (MCP) treatment (0.2 mg/kg orally three times daily), cabergoline (CAB) treatment (5 μg/kg orally once daily), post-treatment 1 and post-treatment 2. In the latter, only semen characteristics were evaluated. Semen parameters were analyzed once per week during the whole 15-week investigation time. At the end of each period, the effects of a single intravenous injection of thyrotropin-releasing hormone (TRH; 10 μg/kg) on the secretion of prolactin (PRL), LH, testosterone, thyroid-stimulating hormone and thyroxine (T4) were investigated. Pre-treatment serum PRL concentration increased under MCP (p < 0.05), followed by a decrease under CAB administration (p < 0.05). Luteinizing hormone and testosterone concentrations were not affected. Except for straight-line sperm velocity, semen quality did not differ between collection periods. A single iv TRH injection induced a significant PRL increase at 20 min in all experimental periods except during CAB treatment. Luteinizing hormone and testosterone did not show clear TRH-related changes. Basic T4 levels were significantly reduced after CAB treatment (p < 0.05). The results of the present study demonstrate that MCP-induced short-term hyperprolactinaemia in male beagles does not seriously affect the hypothalamo-pituitary axis and semen quality.     

Light and electron microscopic study of the livers of pregnant mice infected with Listeria monocytogenes.

Listeria monocytogenes cells were observed in the hepatic cell cytoplasm or in the phagosome at 24 and 48 hours but not at 72 hours after inoculation in pregnant mice. The presence of bacteria initially in a membrane-bound vesicle indicates that the bacteria enter the hepatic cells by endocytosis, resulting in eventual destruction of hepatic cells. Characteristic lesions of the liver at 24 and 48 hours after inoculation consist of multiple focal areas of necrosis. The initial neutrophilic reaction seems to give way to a mononuclear reaction (listeriomas) at 72 hours after inoculation. Dilation of rough endoplasmic reticulum and release of many of the bound ribosomes with a relative increase in the number of free ribosomes was observed. Hepatic lesions were not observed in control (nonpregnant) mice.     

Coral record of equatorial sea-surface temperatures during the penultimate deglaciation at huon peninsula

Uplifted coral terraces at Huon Peninsula, Papua New Guinea, preserve a record of sea level, sea-surface temperature, and salinity from the penultimate deglaciation. Remnants have been found of a shallow-water reef that formed during a pause, similar to the Younger Dryas, in the penultimate deglaciation at 130,000 +/- 2000 years ago, when sea level was 60 to 80 meters lower than it is today. Porites coral, which grew during this period, has oxygen isotopic values and strontium/calcium ratios that indicate that sea-surface temperatures were much cooler (22 degrees +/- 2 degreesC) than either Last Interglacial or present-day tropical temperatures (29 degrees +/- 1 degreesC). These observations provide further evidence for a major cooling of the equatorial western Pacific followed by an extremely rapid rise in sea level during the latter stages of Termination II.     

Influence of Temperature during Glycerol Addition and Post-thaw Dilution on the Quality of Canine Frozen Semen

Contents The aim of the present study was to compare the influence of room temperature (27 degrees C) and 4 degrees C during glycerol addition on canine semen cryopreservation and verify the effect of different post-thawing dilutions on canine semen. Ten ejaculates from five stud dogs were collected by digital manipulation. Semen samples were evaluated and further divided into two aliquots. The first aliquot was extended in Tris-egg yolk-glycerol at 27 degrees C and the second one received glycerol at 4 degrees C. Samples were frozen and stored in liquid nitrogen. After 1 week, samples were thawed and submitted to evaluations of progressive sperm motility, morphology, acrosomal integrity, hypo-osmotic swelling (HOST) and thermoresistance tests. For thermoresistance test, aliquots were divided in two portions: one portion was kept undiluted (1 : 0) and the other one was diluted in a 1 : 4 ratio (one part semen to four parts extender). No differences were observed between temperatures for glycerol addition regarding seminal parameters evaluated. Furthermore, post-thawing dilutions demonstrated similar effect on canine semen longevity. Correlations among post-thaw sperm motility and HOST and results from thermoresistance test were observed for both temperatures for glycerol addition. In conclusion, glycerol could be added to canine semen at room temperature (27 degrees C) or at 4 degrees C. Moreover, there is no need to extend canine semen after thawing for the thermoresistance test, but if we need to increase the inseminating volume for artificial inseminations, the addition of extender will not damage the semen.     

The effect of antibody to caseous lymphadenitis in ewes on the efficacy of vaccination in lambs

The effect of maternal antibody to the toxin of Corynebacterium pseudotuberculosis, produced by caseous lymphadenitis (CLA) in ewes or by vaccinating ewes before lambing, on the efficacy of vaccination against CLA in their lambs was examined. Lambs were allocated to treatments according to either the vaccination history of their dam or level of CLA toxin antibody of their dam. They were vaccinated twice using 2 different inoculation regimes and then artificially infected with CLA organisms. The number of lambs with CLA lesions was assessed at slaughter. In one experiment high levels of CLA toxin antibody activity in ewes were associated with decreased efficacy of CLA vaccination in their lambs, when lambs were vaccinated at 2 and 8 weeks or 8 and 14 weeks of age. In a second experiment the efficacy of lamb vaccination at 8 and 12 weeks, but not at 14 and 18 weeks of age, was decreased. In sheep flocks with a high prevalence of CLA, vaccinating lambs against CLA at less than 10 weeks of age may not produce optimum protection against CLA in lambs. There was no difference in infection rate between lambs from vaccinated and unvaccinated ewes. However, vaccination of lambs at 2 and 8 wks was less effective that vaccination at 8 and 14 weeks, probably due to reduced immunocompetence in young lambs. In sheep flocks where significant numbers of lambs receive their primary vaccination at less than 3 weeks of age vaccination programmes to control CLA in lambs may be less effective.