A cytogenetic study of breeding boars in Canada.

Chromosome abnormalities are well known for their negative impact on the reproductive performance of carriers. Such abnormalities could have severe effect on animal industries which rely heavily on efficient reproduction. We conducted a cytogenetic survey of breeder pigs from 4 different Canadian farms to investigate the frequency of chromosome abnormalities and to assess their reproductive impact on pig populations. Our study revealed that 50% of the 'hypoprolific' boars and 2.5% of the young boars raised for service in artificial insemination were carriers of chromosome anomalies while no chromosome defect was noted in any of the 'proven' breeder boars. G-banding technique to determine the type of abnormalities detected 3 previously unreported translocations involving chromosomes 1 and 6, chromosomes 10 and 13 and chromosomes 9 and 14. The reciprocal nature of these translocations was confirmed either using fluorescent in situ hybridization (FISH) technique or immunostaining for synaptonemal complex delineation and were named rcp(1;6)(p22,q12), rcp(10;13), and rcp(9;14) (p24;q27), respectively. Prolificacy of 1/6 and 10/13 translocation carriers was noted to be reduced by more than 40% compared to their normal counterparts while it was reduced by 26% in carriers of the 9/14 translocation. Carriers of 1/6 and 9/14 translocations displayed a higher repeat breeding tendency, compared to their herd average (5 and 16%, respectively). While for the 9/14 translocation the prevalence of stillbirths was lower than that in their herd [8.7 vs. 10.4% (p < 0.001)]. The present results, albeit based on a relatively small number of pigs, indicate that the prevalence of chromosome abnormalities could be much higher in Canadian pigs compared to that reported in European pigs and underline the urgent need to initiate cytogenetic screening programs as one of the effective ways to reduce reproductive problems in Canadian pig populations.

Meiotic recombination in normal and clone bulls and their offspring.

Homologous chromosome pairing and recombination are essential components of meiosis and sexual reproduction. The reshuffling of genetic material through breakage and reunion of chromatids ensure proper segregation of homologous chromosomes in reduction division and genetic diversity in the progeny. The advent of somatic cell nuclear transfer (SCNT) as a reproductive biotechnology for use in livestock industry has made it easy to bypass these vital steps. However, few studies have been carried out on the impact of SCNT on the reproductive characteristics of cloned animals and, none to date, on the meiotic processes in animals, which were created by circumventing meiosis. In an attempt to assess the impact of cloning by SCNT on the meiotic processes, we undertook an immunocytological comparison of recombination in normal and clone bulls using antibodies raised against the synaptonemal complex protein 3 (SCP3) to label the lateral elements and the mismatch repair protein 1 (MLH1) foci on bivalents as indicators of recombination events. Our studies involving five normal bulls of proven fertility, two SCNT-derived bulls, and four mature offspring of SCNT bulls showed that the mean number of crossing over per spermatocyte for normal bulls (42 +/- 4 SD; ranging from 33 to 56), was not significantly different from that of SCNT-derived bulls (43 +/- 5 SD; ranging from 35 to 56), and the offspring of SCNT-derived bulls (43 +/- 5 SD; ranging from 37 to 58). It would appear that circumventing meiosis to produce these animals does not influence the meiotic processes revealed by MLH1 foci detected in spermatocytes.

Relationships between ultrasonographic image attributes, histomorphology and proliferating cell nuclear antigen expression of bovine antral follicles and corpora lutea ex situ.

The aim of this study was to examine the relationships between quantitative ultrasonographic image characteristics, histological attributes and cell proliferating ability of bovine antral follicles and corpora lutea (CL) ex situ. Bovine ovaries (n = 30) from animals at various reproductive states (metoestrus-early dioestrus, n = 8; mid-dioestrus, n = 12; oestrous phase of peripubertal heifers, n = 6; and pregnancy, n = 4) were collected at the slaughterhouse. High-resolution ultrasonographic images of the ovaries were obtained in the water bath, digitized and subjected to computerized image analyses. The analyses utilized line and spot techniques designed to determine pixel values of the follicular wall (the largest follicles >2 mm in diameter in each ovary) and CL, respectively. Individual ovarian structures were dissected and processed for histology and immunohistochemical detection of proliferating cell nuclear antigen (PCNA). The mean follicular diameter was negatively correlated with total cell density (r = -0.45, p < 0.05), granulosa layer thickness (r = -0.67, p < 0.001) and the percentage of PCNA-positive cells (r = -0.57, p < 0.001). Numerical pixel values and heterogeneity of the follicular wall were positively correlated with total cell density (r = 0.42, p < 0.05 and r = 0.62, p < 0.05; respectively), granulosa layer thickness (both r = 0.39, p < 0.05), and the percentage of PCNA-positive cells (r = 0.54, p < 0.01 and r = 0.69, p < 0.001, respectively). Estimates of cell density and proliferating cell index were not correlated with the ultrasonographic image attributes of CL. We conclude that follicular size and echotextural variables, as determined by computer-assisted image analysis of ovaries ex situ, are reliable markers of the histophysiological properties of bovine antral follicles, but the ultrasonographic characteristics are not indicative of cell density and proliferation in the bovine CL.

Ultrasonographic characteristics of ovulatory follicles and associated endocrine changes in cyclic ewes treated with medroxyprogesterone acetate (MAP)-releasing intravaginal sponges and equine chorionic gonadotropin (eCG).

The aim of this study was to assess the ultrasonographic characteristics of ovulatory follicles in cyclic Western White Face ewes (December) that had received intravaginal sponges containing medroxyprogesterone acetate (MAP; 60 mg) for 12 days, with or without an injection of 500 IU of equine chorionic gonadotropin (eCG) at sponge removal. We hypothesized that quantitative echotextural attributes of the follicles in ewes treated only with MAP would differ from those in MAP/eCG-treated ewes, reflecting the increased antral follicular growth and secretory function under eCG influence. Digital images of ovulatory follicles obtained at 0 and 24 h after MAP sponge removal and at 24 h before ovulation in the eCG-treated (five ewes, 13 follicles) and control (six ewes, 9 follicles) animals, were subjected to computerized analyses. The mean diameter of ovulatory follicles increased (p < 0.001) 24 h after eCG treatment. The mean pixel intensity and heterogeneity of the follicular antrum (p < 0.001), as well as mean pixel intensity of the follicular wall and perifollicular ovarian stroma (p < 0.05), were greater in eCG-treated animals compared with control ewes 24 h after sponge removal and at 24 h before ovulation. Mean serum concentrations of oestradiol-17beta tended to increase (p = 0.06) 24 h after eCG treatment and the eCG-treated ewes exceeded (p < 0.05) control animals in progesterone concentrations from days 9-15 after ovulation. Our results support the hypothesis that large antral follicles in eCG-treated ewes exhibit distinctive echotextural characteristics. Follicular image attributes in eCG-treated ewes appear to be indicative of the changes in follicular morphology and secretory activity caused by the administration of the exogenous gonadotropin, which has both FSH- and LH-like activities.

Ultrasonographic image attributes of non-ovulatory follicles and follicles with different luteal outcomes in gonadotropin-releasing hormone (GnRH)-treated anestrous ewes.

Ultrasonographic images are composed of multiple square picture elements called pixels. Quantitative changes in numerical pixel values (echotexture) determined by computer-assisted analysis of digital images reflect discrete changes in the microscopic structure and physiological status of ovarian antral follicles. The objective of the present study was to determine and compare the ultrasonographic attributes of non-ovulatory antral follicles that grew to an ostensibly ovulatory diameter (> or =5mm) and follicles with different luteal outcomes in response to gonadotropin-releasing hormone (GnRH) in anestrous Western White Face ewes (n=34). All animals received GnRH injections (250ng i.v. every 2h for 24h) followed by a bolus injection of 125microg of GnRH i.v. Ovarian images obtained by repeated transrectal ultrasonography were digitized and subjected to computerized analyses to determine the changes in follicular size and echotexture of the follicular antrum and wall. At the beginning of GnRH treatment, follicles that formed inadequate corpora lutea following ovulation (ICL; n=22) had higher (P<0.001) pixel intensity of the central and peripheral antrum compared with non-ovulatory follicles (n=40). Pixel intensity of the central follicular antrum was greater (P<0.01) in follicles that formed ICL compared with follicles that formed normal (full-lifespan) CL post-treatment (NCL; n=20) and mean pixel heterogeneity of the follicular wall was greater (P<0.05) in non-ovulatory follicles compared with follicles that gave rise to NCL. At the time of GnRH bolus injection (i.e., induction of a synchronous LH surge), the mean diameter of non-ovulatory follicles was greater (P<0.01) than that of all ovulating follicles, and pixel heterogeneity of the central follicular antrum was lowest (P<0.05) in non-ovulatory follicles. The mean diameter of luteinized unovulated follicles (n=9) tended to be greater (P<0.10) at 2.5 and 3 days after emergence, and pixel intensity of the follicular wall was lower (P<0.05) compared with non-luteinized follicles (n=8) at 1.5 and 2.5 days after emergence (beginning of the growth from approximately 3mm onwards). In conclusion, ovarian antral follicles with different outcomes after GnRH treatment (in seasonally anestrous ewes) had distinctive ultrasonographic characteristics.

Lack of effect of protein deprivation-induced intrauterine growth retardation on behavior and corticosterone and growth hormone secretion in adult male rats: a long-term follow-up study.

To further define the neuroendocrine consequences of intrauterine growth retardation (IUGR), we have used a rat model of maternal protein restriction throughout pregnancy to examine the pattern of corticosterone and GH secretion under basal conditions and in response to psychological stress in male offspring at 4, 9, and 18 months of age. The findings were correlated with studies of behavioral activity. Despite a consistent reduction in birth weight and failure of catch-up growth, there were no significant differences in GH secretory profiles between IUGR and control rats at any age. We were unable to demonstrate a difference in the number, amplitude, length, or area of corticosterone secretory pulses between control and IUGR animals; although again, there was a significant decrease with age. The mean peak plasma concentration of corticosterone in response to a noise stress also declined with age but was unaffected by IUGR. There were no consistent, statistically significant differences in behavioral responses between normal control and IUGR animals or between groups of animals at different ages. These results do not, therefore, support the presence of major functional abnormalities in either GH or corticosterone secretory responses in adult male rats subjected to IUGR.

Intra-uterine growth retardation results in increased cardiac arrhythmias and raised diastolic blood pressure in adult rats.

OBJECTIVES: Epidemiological evidence in humans suggests that intrauterine growth retardation is associated with an increased risk of hypertension and coronary heart disease in later life. To begin to understand the mechanisms involved, we developed and exploited a rat model of intrauterine growth retardation to assess predisposition to arrhythmias and resting blood pressure levels at defined ages from 4 to 18 months. METHODS: Isolated working heart experiments were carried out on rats that had been subjected to intrauterine growth retardation by prenatal protein deprivation and age-matched male Wistar controls to measure susceptibility to wall stress-induced arrhythmias. In addition, resting systolic and diastolic blood pressures were measured in conscious rats via an indwelling arterial catheter. RESULTS: Hearts from intrauterine growth retarded animals showed significantly more ventricular premature beats and more episodes of ventricular tachycardia at all ages examined (4, 9 and 18 months), and at 4 and 18 months, a reduction in coronary blood flow. Diastolic pressure was significantly raised by intrauterine growth retardation in both groups examined (4 and 9 months). CONCLUSIONS: Protein malnutrition during the intrauterine period results in profound intrauterine growth retardation that is associated with a raised diastolic blood pressure and an increased predisposition to cardiac arrhythmias in later life. These results are consistent with epidemiological observations made in human populations, and as similar pathophysiological changes may operate in both situations, intrauterine protein deprivation may be a useful model to help define some of the mechanisms involved.

Acquired aphasia in childhood: clinical and CT investigations.

We studied eight children with acquired aphasia. All had left hemisphere lesions. In most, the correlation between the CT lesion site and the resulting aphasic syndrome duplicated an anatomic-clinical correlation described in adults. Rapid recovery of language fluency distinguished the children from reported adults. Late follow-up indicated poor scholastic achievements, reflecting an acquired handicap in new learning. Anatomic-clinical correlates and recovery patterns suggest that brain organization for language is similar but not identical in children and adults.

Neurobehavioral outcome after closed head injury in childhood and adolescence.

Hospital records of 53 children and adolescents, aged 18 years or less, with closed head injury were reviewed for information on long-term outcome. Computed tomographic scans were used to divide the patients into clinicopathologic groups. Within these groups, duration of coma was the major index of severity. Outcome was assessed using the Glasgow Outcome Scale and by evaluating social behavior, school performance, and vocational functioning. Patients with diffuse injury plus focal lesions fared worse than those with diffuse injury only. Coma lasting more than one month led to a poorer outcome in both groups. Many individuals had limiting emotional disturbances, which may have resulted from disruption of frontal systems modulating arousal and social behavior.

Isolation and characterization of a bacteriophage specific for Neisseria perflava.

Six isolates from normal throat samples have been shown to contain phage active against Neisseria perflava. The phage isolates were similar in terms of host range, latent period, burst size, antigenic properties, morphology, and nucleic acid content. Neutralization studies with antisera demonstrated that the isolates exhibited a very high degree of serological relatedness. These results taken together suggested that the isolates represented a single strain of bacteriophage. This phage, which we have designated NP-1, exhibited a high degree of host specificity, attacking only one of the several strains of N. perflava tested and none of the other species tested. One-step growth experiments yielded minimum latent periods of approximately 35 min; average burst sizes varied from 34 to 63 plaque-forming units per cell. Electron micrographs revealed particles with heads averaging 75 nm in diameter and tails averaging 300 nm in length and 18 nm in diameter. The phage contained double-stranded DNA with a guanine plus cytosine content of 38%.