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PubMedDate not supplied

Possible implication of environmental hormones in the recent risk increase of cancers of the skin and the liver, but not of the female breast worldwide.

The invention of 2 contrasting terms "Western type cancer" and "non-Western type cancer" implies that the progress of Westernization of life style for a given population may find its reflection in the balance of cancer risk between a Western type cancer and a non-Western type cancer. Our recent investigation presented evidence to indicate that the incidence of cancers of all sites increased by 32.1% (males) and 18.0% (females) from early 1960s to mid 1980s in the world statistics, and that the observed risk increase of cancers of the skin and liver did not fit the definition of "Westernization effect". It was suggested that the spread of environmental hormones could be related to the increased risks of 2 cancers. This study attempted to test the validity of the above statement by studying comparatively the epidemiological aspects of cancer of the skin, liver and breast, the latter being the reference tumor of the "Westernization effect". Cancer risk for each tumor was expressed in terms of the age-specific incidence rate (ASIR) and age-adjusted incidence rate (AAIR). For mathematical reasons, both ASIR- and AAIR-data were transformed into their logarithms before statistical analysis. We prepared the world population model with a size of 38 population units to investigate the relation between reproductive activity and cancer risk. Results obtained are as follows: a) the log AAIR of liver cancer was positively correlated to 2 parameters of reproductive activity in the female world population, and failed to show any correlation to the same 2 parameters in the male world population. The above finding was taken as evidence to indicate that liver cancer still retained its characteristics as a cancer of non-Western type with male predominancy of cancer risk. b) The log AAIR of skin cancer was negatively correlated to 2 parameters of reproductive activity in the world populations of both sexes--reconfirmation of skin cancer as of the Western type. c) In the period of early 1960s to mid 1980s the log AAIR of liver cancer of both sexes underwent exponential growth in Japan, slow and straight-line growth in 3 non-hispanic White populations, and no significant change in 2 Hispanic populations. d) The chronological follow-up study of log ASIR profile of both liver cancer in Japan and skin cancer in England revealed 3 common traits of cancer risk boost: i) quick and distinct ascension of cancer risk of all ages; ii) elongation of the young- age tail of the ASIR profile towards the 0 year limit; iii) emergence of a new infant type cancer profile independent of the existing adult type cancer profile. Possible implication of environmental hormones in human embryogenesis was suggested as an explanation for the genesis of an infant type cancer. e) Comparative study of log ASIR profiles of breast cancer between England and Japan did not support possible implication of environmental hormones in the recent rise of breast cancer risk throughout the world. f) The eligibility of cancers of the liver and skin as the targets of environmental hormones was discussed in the light of up-to-date data of epidemiology and experimental pathology.

Age Factors↗
PubMed1994

Genetic parameters for yield and reproductive traits of Holstein and Jersey cattle in Florida.

Records of yield and reproduction from 4293 Holstein and 2143 Jersey first lactation cows from eight Holstein and six Jersey herds were utilized to evaluate genetic parameters for Florida, a subtropical environment. Statistical analyses were by derivative-free REML with the animal model. Genetic variances were based on variation in estimated breeding values of individual cows. Heritabilities were .27 to .43 for yields (6 estimates), .38 to .51 for constituent percentages (4 estimates), and .025 to .056 for reproduction (6 estimates), which were similar to estimates for temperature areas from similar procedures. Also, correlations of breeding values between yields were high and between yields and reproduction were low and generally antagonistic. Correlated responses in calving interval from selection for yield, with selection intensities of 1.0 to 1.5, would be expected to lead to increases of 1.0 to 5.2 d per generation (12 estimates). Thus, estimates of genetic parameters and correlated responses in this subtropical environment did not differ appreciably from those that occur in temperate dairy areas.

Animals↗
PubMed2003

Diabetes (db/db) mutation-induced ovarian involution: progressive hypercytolipidemia.

Ovarian atrophy and reproductive tract incompetence are recognized consequences of the progressive expression of the overt, diabetes-obesity syndrome (DOS) in C57BL/KsJ (db/db) mutant mice. The present studies evaluated the progressive changes in ovarian cytoarchitecture, endocrine expression, and reproductive tract cytolipidemic parameters that promote reproductive failure and ovarian involution during the pre-onset, initial, progressive, and chronic expression stages of the DOS. Paired littermate control (normal: +/?) and diabetic (mutant: db/db) C57BL/KsJ females were selected for analysis of ovarian parameters at 2 weeks (pre-onset expression of DOS), 4 weeks (initial DOS expression), 8 weeks (progressive DOS: hyper-glycemic/lipidemic), and 16 weeks (overt/chronic DOS expression) of age. All 4- to 16-week-old (db/db) groups were obese, hyperglycemic, and hyperinsulinemic as compared with age-matched (+/?) controls. Prior to phenotypic expression of the DOS (2 week groups), ovarian interstitial cytolipidemia characterized the perifollicular and cortical regions of db/db tissue samples relative to +/? indices, while comparable body weight, blood glucose, as well as serum insulin and ovarian steroid hormone concentrations characterized both the +/? and db/db groups. Overt DOS expression in the 4-week-old db/db groups was characterized by body obesity, systemic hyperglycemia-hyperinsulinemia, and extensive hypercytolipidemia of ovarian folliculothecal compartments, as well as enhanced tissue lipase activities. By 8 weeks of age, progressive hypercytolipidemia characterized interstitial, thecal, and follicular granulosa cell layers of db/db tissue samples concurrent with suppressed ovarian steroid hormone production, enhanced lipid sequestration, and exacerbation of systemic hyper-glycemia/insulinemia. By 16 weeks of age, the chronic-DOS was characterized by extensive ovarian follicular involution, cortical perivascular hyperlipidemic infiltration, thecal cell atrophy, and follicular granulosa lipid imbibition. These data indicate that db/db mutation-induced ovarian structural and functional involution is a direct reflection of the cellular metabolic shift towards lipogenesis, indicated by the progressive cytoarchitectural transformation into adipocyte-like entities. The cytological indications of cellular metabolic compromise, which precede the phenotypic expression of the DOS indices, suggests that correction of these abnormal shifts in ovarian endocrine and cellular metabolism may restore, delay, or prevent the further compromise of ovarian function by db/db mutation expression.

Age Factors↗
PubMed2005

Estimation of genetic parameters of semen characteristics and reproductive traits in AI boars.

(Co)variance components and further genetic parameters of boar semen characteristics and reproductive traits were estimated using the REML procedure applied to multi-trait animal models. The calculations were based on data from 210,733 ejaculates stemming from 2862 AI boars and collected from 1990 to 1997 in insemination stations for boars in the Czech Republic. Equal model equations for all traits included the AI station and the breed or breed combination as fixed effects, the interval between two collections for the boar as covariable and the animal and residual effects as random effects. The following heritabilities were estimated: semen volume 0.58, sperm concentration 0.49, progressive motion of spermatozoa 0.38, abnormal spermatozoa 0.34, number of total spermatozoa 0.42, number of insemination doses 0.40, number of piglets born alive 0.08, total number of piglets born 0.05 and conception rate 0.29. Heritabilities and genetic correlations were estimated on average values for each boar.

Animals↗
PubMed2006

Long-term exposure of female sheep to physiologic concentrations of estradiol: effects on the onset and maintenance of reproductive function, pregnancy, and social development in female offspring.

As steroids and steroid-like compounds accumulate in the environment, it has become important to understand how low-dose exposure affects reproductive function. Ovary-intact sheep were used in a multigenerational study, to determine whether chronic exposure to low levels of estrogen disrupts reproductive function and behavior. We assessed parameters of reproductive performance in control and postnatally estradiol-treated females (Generation 1, G1), and their offspring (Generation 2, G2). In the G1 animals, 17beta-estradiol (E) was administered continuously from 4 wk of age at two doses via subcutaneous implants (ultralow E [<1 pg/ml in circulation, n = 8] or low E [1-3 pg/ml, n = 8]). Both doses delayed puberty; low E also produced pronounced prepubertal and seasonal anestrus hypogonadotropism, and delayed the onset of the second breeding season. All G1 animals conceived and produced offspring (G2), the treatment of which resulted from continuous maternal exposure during pregnancy and lactation. Behavioral observations of G2 females revealed that low prenatal E modestly masculinized play behavior and increased the frequency of attempts to displace competitors relative to ultralow E and control animals. The timing and magnitude of the LH surge also differed in prepubertal low prenatal E females relative to the controls, although these differences were not evident when retested at one year of age. These findings support the hypothesis that chronic exposure to physiologic amounts of exogenous estrogens has multigenerational effects on behavior and neuroendocrine function. Despite these disruptive steroid actions, ovarian cyclicity and fertility are not invariably compromised, pointing to an impressive resiliency of the reproductive axis to insult by exogenous estrogenic compounds.

Animals↗
PubMed1995

Comparison of parameters to study seasonality in reproductive outcome.

This report compares validity, precision and convenience of three frequently used parameters used to describe seasonality in reproductive outcome: prevalence, index and ratio observed versus expected. Each has its advantages and disadvantages; the choice of the parameter depends on the aim of the study. It is advisable to report the number of cases and referents per month, because all three parameters can be derived from this information.

Birth Rate↗
PubMed2006

The effect of long term exposure to copper on physiological condition and reproduction of sheep.

The influence of copper upon some physiological parameters and reproduction in ewes was studied. Four groups of animals were investigated: 1/ control ewes (untreated); 2) ewes receiving copper as a supplement over the recommended amount of copper in food (10, 25 or 50 mg Cu/ewe/day); 3/ control, superovulated ewes; and 4) ewes treated with 50 mg copper during one month and then superovulated. After 10 months of daily exposure to 10 mg of copper/ewe/day no signs of toxicity on physiological condition and reproduction were found. In ewes exposed to 25 or 50 mg of copper a decrease in blood parameters and increase in concentration of Cu in blood and liver were noticed. The wavy pattern of follicles was disturbed and disorders in fecundity, prolificacy and pregnancy occurred. Significant differences between the number of corpora lutea in superovulated control animals and experimental (Cu 50 mg) ewes were observed.

Animals↗
PubMed2002

Estimates of genetic parameters and genetic change for reproduction, weight, and wool characteristics of Columbia sheep.

Genetic parameters from both single-trait and bivariate analyses for prolificacy, weight and wool traits were estimated using REML with animal models for Columbia sheep from data collected from 1950 to 1998 at the U.S. Sheep Experiment Station (USSES), Dubois, ID. Breeding values from both single-trait and seven-trait analyses calculated using the parameters estimated from the single-trait and bivariate analyses were compared with respect to genetic trends. Number of observations were 31,401 for litter size at birth and litter size at weaning, 24,741 for birth weight, 23,903 for weaning weight, 29,572 for fleece weight and fleece grade, and 2,449 for staple length. Direct heritability estimates from single-trait analyses were 0.09 for litter size at birth, 0.06 for litter size at weaning, 0.27 for birth weight, 0.16 for weaning weight, 0.53 for fleece weight, 0.41 for fleece grade, and 0.55 for staple length. Estimate of direct genetic correlation between littersize at birth and weaning was 0.84 and between birth and weaning weights was 0.56. Estimate of genetic correlation between fleece weight and staple length was positive (0.55) but negative between fleece weight and fleece grade (-0.47) and between staple length and fleece grade (-0.70). Estimates of genetic correlations were positive but small between birth weight and litter size traits and moderate and positive between weaning weight and litter size traits. Fleece weight was lowly and negatively correlated with both litter size traits. Fleece grade was lowly and positively correlated with both litter size traits, while staple length was lowly and negatively correlated with the litter size traits. Estimates of correlations between weight traits and fleece weight were positive and low to moderate. Estimates of correlations between weight traits and fleece grade were negative and small. Estimates of correlations between staple length and birth weight (0.05) and weaning weight were small (-0.04). Estimated breeding values averaged by year of birth from both the single-trait and multiple-trait analyses for the prolificacy and weight traits increased over time, but were unchanged for the wool traits. Estimated changes in breeding values over time did not differ substantially for single-trait and multiple-trait analyses, except for traits highly correlated with another trait that was responding to selection.

Animals↗
PubMed2003

Estimates of genetic parameters and genetic change for reproduction, weight, and wool characteristics of Targhee sheep.

Genetic parameters from both single-trait and bivariate analyses for prolificacy, weight, and wool traits were estimated using REML with animal models for Targhee sheep from data collected from 1950 to 1998 at the U.S. Sheep Experiment Station, Dubois, ID. Breeding values from both single-trait and seven-trait analyses calculated with the parameters estimated from the single-trait and bivariate analyses were compared across years of birth with respect to genetic trends. The numbers of observations were 38,625 for litter size at birth and litter size at weaning, 33,994 for birth weight, 32,715 for weaning weight, 36,807 for fleece weight and fleece grade, and 3,341 for staple length. Direct heritability estimates from single-trait analyses were 0.10 for litter size at birth, 0.07 for litter size at weaning, 0.25 for birth weight, 0.22 for weaning weight, 0.54 for fleece weight, 0.41 for fleece grade, and 0.65 for staple length. Estimate of direct genetic correlation between litter size at birth and weaning was 0.77 and between birth and weaning weights was 0.52. The estimate of genetic correlation between fleece weight and staple length was positive (0.54), but was negative between fleece weight and fleece grade (-0.47) and between staple length and fleece grade (-0.69). Estimates of genetic correlations were near zero between birth weight and litter size traits and small and positive between weaning weight and litter size traits. Fleece weight was slightly and negatively correlated with both litter size traits. Fleece grade was slightly and positively correlated with both litter size traits. Estimates of correlations between staple length and litter size at birth (-0.14) and litter size at weaning (0.05) were small. Estimates of correlations between weight traits and fleece weight were positive and low to moderate. Estimates of correlations between weight traits and fleece grade were negative and small, whereas estimates between weight traits and staple length were positive and small. Estimated breeding values averaged by year of birth from both the single- and seven-trait analyses for the prolificacy and weight traits increased over time, whereas those for fleece weight decreased slightly and those for the other wool traits were unchanged. Estimated changes in breeding values over time did not differ substantially for the single-trait and seven-trait analyses, except for traits highly correlated with another trait that was responding to selection.

Animals↗
PubMed1999

[Pleiotropic effect of the Black crystal mutation on reproductive indicators in the American mink (Mustela vison)].

The parameters of reproduction were studied in American minks that were homo- and heterozygous for the Black crystal mutation (Cr). The given mutation that changes the hair pigmentation was obtained de novo duration selection of American minks for tame behavior. Apart from changed color, the following reproduction disorders were detected in the Black crystal mutants, as compared to standard animals: (1) delayed entry into the reproductive season in females; (2) greater percentage in both homo- and heterozygous animals of females bearing no offspring; (3) greater early postnatal lethality indices. The most marked suppressing effect on the development of offspring was detected in homozygous females (Cr/Cr), whose progeny perished within a few days after birth. An analysis of reproduction in mutants and standard animals is presented. An attempt was made to explain the conceivable mechanisms that form the basis of disorders detected.

Animals↗
PubMed1994

Return to oestrus after first insemination in sow herds (incidence, seasonality, and association with reproductivity and some blood parameters).

As no systematic study has been done to get an accurate estimate of the incidence of return to oestrus after first insemination in sows in the Netherlands, the objectives of this investigation were: 1) to obtain an estimate of the incidence of return to oestrus after insemination at the herd level; 2) to investigate the association between incidence of return to oestrus after first insemination and reproduction characteristics in order to get an impression of the economic importance of reproductive failure. These objectives were investigated by using the reproduction results of 240 swine breeding herds in the Southern Netherlands in 1987. This information was obtained from CBK plus computerized herd management records. The average incidence rate of return to oestrus after first insemination at a herd level was 16.9 per 100 first inseminations. The occurrence of return to oestrus after first insemination was distinctly higher in the insemination months July and August compared to the rest of the year. An increased incidence, with 10 returns per 100 first inseminations corrected for confounders in a multiple linear regression model, was associated with a decrease of approximately 0.3 live born piglets/sow/year. A prospective longitudinal study was started in 1988 and 1989 in 37 sow herds. Individual sows were monitored from weaning to first insemination, to the occurrence of return to oestrus, or not, after first insemination, and to farrowing. The investigation focused in particular on the relationship between return to oestrus after first insemination and seroconversion against porcine parvovirus (PPV) and Leptospira interrogans serovar bratislava (L. bratislava).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Return to estrus following first insemination in sow herds (incidence and association with reproductivity and various blood parameters)].

As no systematic study has been done to get an accurate estimate of the incidence of return to oestrus after first insemination in sows in the Netherlands, the objectives of this investigation were: 1) to obtain an estimate of the incidence of return to oestrus after insemination at the herd level; 2) to investigate the association between incidence of return to oestrus after first insemination and reproduction characteristics to get an impression of the economic importance. These objectives were investigated using the reproduction results of 240 swine breeding herds in The Southern Netherlands in 1987, using their CBK plus computerized herd management records. The average incidence of return to oestrus after first insemination on a herd level was 16.9 per 100 first inseminations. An increase of incidence with 10 returns per 100 first inseminations, corrected for confounders in a multiple linear regression model, was associated with a decrease of approximately 0.3 liveborn piglets/sow/year. Thereupon individual sows were followed in 1988 and 1989 prospectively in 37 sow herds from weaning to insemination, returning to oestrus or not after first insemination to farrowing. The investigation focused in particular on the relationship between returning to oestrus after first insemination and incident infection with porcine parvovirus (PPV) and Leptospira interrogans serovar bratislava (L. bratislava). During a number of consecutive farm visits sows were blood sampled at weaning and again a blood sample was taken 6 weeks later. The final dataset that was analysed consisted of 161 animals that did not return to oestrus after first insemination and 158 animals that returned to oestrus after first insemination.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effects of an LH-RH agonist on reproductive responses and endocrinological parameters in landais ganders.

Semen quantitative (sperm production) and qualitative parameters (percentage of live and normal spermatozoa, sperm motility, egg fertility and hatchability), as well as hormonal parameters (LH and testosterone plasma concentrations) were compared for landais ganders, which were treated or not, with an LH-RH agonist prior to being sexually active. Treatment with the LH-RH agonist at this physiological stage delayed the onset of sperm production in some of the treated males. Although, comparable data were obtained during the first half of the reproductive period, treatment with the LH-RH agonist maintained sperm output at higher levels during its second half. Although the percentage of normal and live spermatozoa, sperm motility and true hatchability did not differ, the LH-RH agonist treatment had a positive effect on gosling production because of the higher fertility of the treated birds during the second part of the reproductive period. Treatment induced a large short-term decrease in testosterone levels followed by a rebound, leading to higher levels during the second half of the reproductive period. We conclude that treatment of ganders with an LH-RH agonist partially prevented the naturally occurring decline in sperm production and induced an increase in the rate of fertility rates during the second half of the productive period.

Journal Article↗
PubMed1989

[Effect of progestin therapy on the level of cytoplasmic receptors in patients with cancer of the corpus uteri].

Correlations were identified between tumor morphobiochemical characteristics and basic parameters of reproductive homeostasis in 256 cases of endometrial carcinoma. A correlation was established between the levels of cytoplasmic receptors to estradiol (ER) and progesterone (PR), on the one hand, and morphological differentiation and spontaneous secretion in tumor tissue, on the other. A direct correlation was found between ER and metastatic spread to regional lymph nodes, and no correlation--between ER and PR and major parameters of reproductive homeostasis. A significant decrease in ER, PR, gonadotropins, estradiol and colpocytological reaction indexes followed hormone therapy with hydroxyprogesterone capronate and medroxyprogesterone acetate. The criteria of endometrial carcinoma patients sensitivity to progestin therapy were as follows: ER and PR levels--more than 30.0 fmol/mg protein, estradiol--more than 30-50 pg/ml and colpocytological index--over 40%.

17 alpha-Hydroxyprogesterone Caproate↗
PubMed1989

1,3-dichloropropene: two-generation inhalation reproduction study in Fischer 344 rats.

This study evaluated the effects of inhaled technical-grade 1,3-dichloropropene (DCPT) on reproduction and neonatal growth and survival. Groups of 30 male and 30 female Fischer 344 rats, approximately 6 weeks of age, were exposed via inhalation to 0, 10, 30 or 90 ppm DCPT for 6 hr/day, 5 days/week, for two generations. The parental f0 and f1 generations were each bred twice. Reproductive and neonatal parameters evaluated included indices of fertility and pup survival, gestation length, litter size, pup body weight, and pup sex ratio. Gross and histologic examinations were concluded on all f0 and f1 adults. In addition, randomly selected f1b and f2b weanlings were given gross examinations. Parental effects were limited to rats exposed to 90 ppm DCPT and included decreased body weights and histopathologic effects on the nasal mucosa of adult male and female rats. The histopathologic effects consisted of slight, focal hyperplasia of the respiratory epithelium and/or focal degenerative changes in the olfactory epithelium. No adverse effects on reproductive parameters or neonatal growth or survival were observed in the f1a, f1b, f2a, or f2b litters even at an exposure concentration which produced effects in adult animals. Based on these results, it is concluded that inhalation exposure of rats up to 90 ppm DCPT for two successive generations did not adversely affect the reproductive and neonatal parameters evaluated.

Administration, Inhalation↗
PubMed2003

Reproduction, blood and plasma parameters and gill histology of vendace (Coregonus albula L.) in long-term exposure to acidity and aluminum.

Vendace were exposed to pHs 4.75 and 5.25 with or without added aluminum (200 microg=7.4 micromol AlL(-1)) from late endogenous vitellogenesis in July through the spawning period. At the normal time of spawning, when 48% of the control females had already released their eggs, 50% of females at pH 4.75+Al had completely unovulated oocytes. The final proportions of completely ovulated females were 14%, 36%, 25%, 61%, and 81% at pH 4.75+Al, pH 4.75, pH 5.25+Al, pH 5.25, and in the control group, respectively. Delayed testes regression was seen in males at pH 4.75+Al. A clear decrease in plasma Na(+) and Cl(-) and an increase in blood glucose concentration was detected only near spawning time, from October to November, coincident with Al accumulation inside the gill tissue. It is concluded that seasonal changes, probably related to reproductive physiology or to the decrease in water temperature, are associated with the increase in Al toxicity in vendace.

Aluminum↗
PubMed1999

The effect of subclinical experimental Cowdria ruminantium infection on the health and reproductive performance of breeding ewes.

This study documented the effect on the productivity of Dorper-Merino cross ewes when they became infected with Cowdria ruminantium as would occur in an endemically stable state. A flock of 152 breeding ewes was randomly divided into two matched groups. One group was infected on multiple occasions with C. ruminantium; the other group remained uninfected. The ewes were bred and monitored for one breeding/lambing/weaning cycle. Hematological, reproductive, and health parameters were recorded at regular intervals. Statistically significant differences in hematological values between the two groups were infrequent and transient. No significant differences in weights, mortality rates or reproductive parameters were detected between the two groups. Subclinical C. ruminantium infection did not negatively affect health and reproductive performance of breeding ewes; endemic stability would be a suitable alternative method of controlling heartwater.

Animals↗