Efficacy of a sperm-selection chamber in terms of morphology, aneuploidy and DNA packaging.

Since most current techniques analysing spermatozoa will inevitably exclude these gametes from further use, attempts have been made to enrich semen samples with physiological spermatozoa with good prognosis using special sperm-processing methods. A particular sperm-selection chamber, called the Zech-selector, was found to be effective in completely eliminating spermatozoa with DNA strand breaks. The aim of this study was to further analyse the subgroup of spermatozoa accumulated using the Zech-selector. In detail, the potential of the chamber to select for proper sperm morphology, DNA status and chromatin condensation was tested. Two samples, native and processed semen, of 53 patients were analysed for sperm morphology (×1000, ×6300), DNA packaging (fragmentation, chromatin condensation) and chromosomal status (X, Y, 18). Migration time (the time needed for proper sperm accumulation) was significantly correlated to fast progressive motility (P=0.002). The present sperm-processing method was highly successful with respect to all parameters analysed (P<0.001). In particular, spermatozoa showing numeric (17.4% of patients without aneuploidy) or structural chromosomal abnormalities (90% of patients without strand-breaks) were separated most effectively. To summarize, further evidence is provided that separating spermatozoa without exposure to centrifugation stress results in a population of highly physiological spermatozoa.

Phenotypic characterisation of a Neospora caninum temperature-sensitive strain in normal and immunodeficient mice.

The in vivo persistence, immunogenicity and pathogenicity of a recently described temperature-sensitive (ts) strain from Neospora caninum, NCts-8, was investigated in normal and immunodeficient mice. Groups of BALB/c and SCID/Bg mice were infected s.c. with 5 x 10(6) wild-type NC-1, control NCts-8 (pass 0) or NCts-8 tachyzoites prepared at four in vitro passage levels (pass 7, 13, 21 and 28). For persistence and immunogenicity studies, BALB/c mice were bled and sacrificed at 4, 6 or 8 weeks p.i. Sera were analysed by IFAT and brain tissues examined for lesions by histology and tested for parasite presence by PCR. For pathogenicity studies, SCID/Bg mice were monitored by clinical signs and survival time. Results from parasite persistence experiments demonstrated microscopic lesions and PCR positive brain tissues in NC-1 infected mice. In contrast, brain tissues from NCts8-infected groups were consistently negative by histology and PCR. Based on IFAT titres, all parasite strains were immunogenic, although parasite-specific IgG levels were lower in the NCts-8 infected groups. Results from pathogenicity studies in SCID/Bg mice demonstrated a significantly (P < 0.0001) longer mean survival time in NCts-8 vs NC-1 infected groups. In addition, there was no significant difference in mean survival time between control NCts-8 and experimental passage NCts-8 infected mice. Collectively, these studies demonstrate that the NCts-8 strain maintains a stable phenotype following multiple passages in vitro, and possesses an attenuated, shorter persistence phenotype in vivo compared with the parental wild-type NC-1.

Characterization of the systemic disease and ocular signs induced by experimental infection with Chlamydia psittaci in cats.

In addition to the commonly reported ocular signs, Chlamydia psittaci infection of kittens resulted in fever, lethargy, lameness and reduction in weight gain following ocular instillation of virulent organisms. The appearance of these systemic signs was late with respect to the appearance of ocular symptoms and occurred simultaneously with increasing levels of chlamydia-specific IgG. Measurement of acute phase reactants and IL-6 in plasma indicated that both became elevated concurrent with or slightly after the appearance of fever and remained elevated after the fever began to resolve. Preliminary data also indicated that infectious C. psittaci was present in the blood stream during this time period. The results of ocular instillation of three different levels of C. psittaci (10(3.8), 10(2.8) and 10(1.5) TCID50) indicated that the frequency of infection and the severity of ocular signs were diminished in the group receiving the lowest dose. However, the magnitude of systemic disease was similar in all animals which exhibited clinical signs, irrespective of the dose administered. The immune response to infection included elementary body (EB)-specific lymphocyte proliferation as well as the development of EB-specific IgG and IgM antibodies. The predominant antibody response was to a 45 kDa protein, the major outer membrane protein (MOMP), lipopolysaccharide (LPS), a 58 kDa doublet and 32 and 16-19 kDa proteins.

Comparison of the primary signs induced by experimental exposure to either a pneumotrophic or a 'limping' strain of feline calicivirus.

Two strains of feline calicivirus, one reportedly pneumotrophic (FPV 255) and the other associated with a limping syndrome (2280) were compared with respect to the signs induced in kittens after oronasal exposure. Neither strain induced severe upper respiratory symptoms, and both caused oral ulcers and lameness. However oral ulcers were more prevalent, and lameness and depression were more pronounced in the kittens which received strain 2280. Kittens which exhibited lameness also had elevated blood levels of alpha 1-acid glycoprotein. A decline in lymphocyte count was noted only in kittens which received strain 2280. These data demonstrate that despite reported antigenic and genetic differences between these strains, no distinct differences in pathogenicity could be determined.

Canine parvovirus vaccine elicits protection from the inflammatory and clinical consequences of the disease.

Inflammatory changes following infection are central to the clinical manifestation of disease. However, information regarding such changes in animal disease is limited. In canine parvovirus infected puppies we measured the levels of acute phase proteins and changes in leukocyte phenotypes and cell trafficking by flow cytometry. These parameters correlated with conventional assessment of clinical disease in a vaccine efficacy study. Seropositive (CPV-2) 6-week-old puppies given three doses of a CPV-2 containing vaccine developed significant antibody titers and remained healthy after experimental infection with CPV-2b. Unvaccinated controls developed clinical signs and shed virus. Importantly, acute phase proteins became elevated, and lymphopenia, neutropenia and modulation of neutrophil-CD4 were detected in controls but not in vaccinates.

The corpus luteum periodicum in the bitch: histochemical and biochemical investigations during different phases of the cycle.

The corpus luteum periodicum (c.l.p.) of the bitch was studied using enzyme histochemistry, clinical and biochemical methods. Assessment of variations of the serum progesterone level during different stages of the ovarian cycle and the study of enzymatic activity of the luteal tissue furnished informations on vitality and biosynthetic capacity of luteinizing cells: The period of functional activity of the c.l.p. nearly ceased about day 60 of the cycle (proestrus included) in the animals examined. In the light microscope the neo-synthesis of progesterone in the c.l.-tissue can be made visible by histochemical demonstration of the activity of Delta(5)-3 beta-hydroxysteroiddehydrogenase (3 beta-HSD) only up to a progesterone level exceeding 6.7 ng/ml plasma. The data obtained contribute to our baseline knowledge of the mechanism involved in the etiology of pseudopregnancylike conditions in the bitch.