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Results for “Reproductive Period”

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At least 433 records · Page 24Linked to original sources

PubMed1997

Maternal obesity and breast-feeding success in a rural population of white women.

Maternal obesity interferes with the initiation and maintenance of lactation in animal models but it has not been investigated widely in women. We reviewed medical records from a white population to examine the relation between prepregnant overweight [body mass index (BMI; in kg/m2) 26.1-29.0] and obesity (BMI > 29.0) on initiation and duration of breast-feeding. Logistic regression revealed that of those who ever put their infants to the breast (n = 810), women who were overweight [odds ratio (OR) = 2.54, P < 0.05] or obese (OR = 3.65, P < 0.0008) had less success initiating breast-feeding than did their normal-weight counterparts (BMI < 26.1). Proportional-hazards regression revealed higher rates of discontinuation of exclusive breast-feeding in overweight (RR = 1.42, P < 0.04) and obese (RR = 1.43, P < 0.02) women and higher discontinuation of breast-feeding to any extent in overweight (RR = 1.68, P < 0.006) and obese (RR = 1.73, P = 0.001) women. Controlling for parity, socioeconomic status, maternal education, and other factors that often covary with maternal obesity and breast-feeding did not change these results. These results suggest that excessive fatness in the reproductive period may inhibit lactational performance in women.

Adult↗

PubMed2003

Characterization and chromosomal instability of novel derived cell lines from a wt-erbB-2 transgenic mouse model.

Amplification and overexpression of the erbB-2 (HER-2/neu) proto-oncogene and exposure to the cell cycle mitogenic hormone estrogen (E2) have been associated with mammary tumorigenesis. Phytoestrogens found in soy act as selective estrogen receptor modulators and may also modify mammary carcinogenesis. We have used the wt-erbB-2 transgenic mouse model to study the effects of estrogen and dietary phytoestrogens on erbB-2-associated mammary tumorigenesis. Transgenic mice were treated with short-term E2 or placebo pellets during the early reproductive period and fed a casein or soy diet for life. Mammary tumors from the different treatment groups were used for the derivation of novel cell lines. Comparative genomic hybridization (CGH), flow cytometry, assays of cell proliferation and soft agar cloning were performed to study genomic instability and in vitro characteristics. CGH data were compared with corresponding parental tumors. Mammary tumors exhibited significantly fewer genetic changes than cell lines by CGH. Cell lines from soy-fed animals (that developed tumors with a longer latency) demonstrated the greatest frequency of chromosomal gain and loss. The E2-treated, casein-fed animals (that developed tumors with the shortest latency) had the fewest genetic changes in derived lines by CGH. Nonetheless, E2-associated tumors in vivo and lines in vitro had the most aggressive phenotypes. In addition, over 40% of all derived cell lines, and both tumors from the placebo-treated casein-fed mice, exhibited loss of chromosome 4 by CGH. In aggregate, our data suggest that estrogenic signaling influences mammary tumor development in this transgenic mouse model bearing the rat wt-erbB-2 gene. Once induced, tumors and derived lines demonstrate persistent phenotypic characteristics, including tumor aggression and shortened latency in E2-treated mice. Loss of chromosome 4 was commonly identified in derived lines and may have facilitated immortalization or passage in culture.

Animals↗

PubMed1988

A mutation in the age-1 gene in Caenorhabditis elegans lengthens life and reduces hermaphrodite fertility.

age-1(hx546) is a recessive mutant allele in Caenorhabditis elegans that results in an increase in mean life span averaging 40% and in maximal life span averaging 60% at 20 degrees; at 25 degrees age-1(hx546) averages a 65% increase in mean life span (25.3 days vs. 15.0 days) and a 110% increase in maximum life span (46.2 days vs. 22.0 days for wild-type hermaphrodites). Mutant males also show extended life spans. age-1(hx546) is associated with a 75% decrease in hermaphrodite self-fertility as compared to the age-1+ allele at 20 degrees. Using two novel strategies for following the segregation of age-1, we present evidence that longer life results from a mutation in a single gene that increases the probability of survival at all chronological ages. The long-life and reduced-fertility phenotypes cosegregate and are tightly linked to fer-15, a locus on linkage group II. age-1(hx546) does not affect the timing of larval molts, the length of embryogenesis, food uptake, movement, or behavior in any way tested. Although age-1(hx546) lowers hermaphrodite self-fertility, it does not markedly affect the length of the reproductive period with all the increase in life expectancy due to an increase in the length of postreproductive life. In so far as we are aware, this mutant in age-1 is the only instance of a well-characterized genetic locus in which the mutant form results in lengthened fife. It is likely that the action of age-1 in lengthening life results not from eliminating a programmed aging function but rather from reduced hermaphrodite self-fertility or from some other unknown metabolic or physiologic alteration.

Alleles↗

PubMed1995

A malathion resistance gene associated with increased life span of the rusty grain beetle, Cryptolestes ferrugineus (Coleoptera: Cucujidae).

The life span of the rusty grain beetle, Cryptolestes ferrugineus, was determined at 30 degrees C, 75% relative humidity (RH) for virgin and mated adults of a malathion-resistant strain (BC6RR), a malathion-susceptible strain (SS), the F1 progeny of a cross between resistant females and susceptible males (RS), and an outbred strain (GV). The BC6RR strain was derived from the SS strain by incorporating the malathion resistance gene into the susceptible genome with six backcrosses and recovery of heterozygous resistant F1 adults between crosses. The mean life span of virgin, malathion-resistant adults (BC6RR and RS) was 37 weeks; the mean life span of virgin, susceptible adults (SS and GV) was 32 weeks. Resistant virgin adults lived significantly longer (15-16%) than susceptible virgin adults, and mated resistant adults lived significantly longer (3-20%) than mated susceptible adults (p < .05). Since C. ferrugineus has a relatively long reproductive period and females with the longest life spans produce the most offspring, life span can be considered an important component of fitness in this insect. The malathion resistance gene did not reduce fitness, and this gene or genes closely linked to it may be responsible for increasing life span in C. ferrugineus.

Animals↗

PubMed1997

Postmenopausal acceleration of age-related mortality increase.

The force of natural selection to eliminate deleterious genes is attenuated with advancing age, allowing senescence to evolve. This suggests that a distinctly marked end of the reproduction period is likely to be followed by an acceleration of senescence. It is thus expected that menopause should trigger an acceleration of age-related mortality increase in human females. Such an abrupt initiation of mortality acceleration is not predicted for human males at the same ages, whose fecundity declines more gradually. Life table aging rate patterns for selected industrialized countries generally support this hypothesis. A cause-of-death decomposition analysis indicates that the sex differential in mortality acceleration is mainly due to cardiovascular diseases, which is consistent with the prevalent view that postmenopausal changes in the sex hormone status may affect lipoprotein metabolism, and in turn, raise the risk of arteriosclerosis.

Adult↗

PubMed1975

Life extension in the rotifer Mytilina brevispina var redunca by the application of chelating agents.

Extensions of life-span and reproductive period were achieved in the rotifer Mytilina brevispina var redunca by regular brief immersions in solutions of one of the following chelating agents, sodium citrate, sodium tartrate, EDTA, and EGTA. It was shown by means of radiolabelling with 45 calcium that the rate of calcium accumulation in chelation-treated rotifers was markedly lower than in the untreated controls. Furthermore, significant quantities of calcium, which increased throughout the life-span, were withdrawn from rotifers at chelation. These results add further evidence to a mechanism of aging in this organism that is related to a detrimental accumulation of calcium during the life period.

Animals↗

PubMed1994

Sex differences in measles mortality: a world review.

BACKGROUND: In general females have a lower mortality than males at all ages. Excess female mortality has been documented in certain high mortality situations, in particular in South Asia. However, females may have a higher mortality for certain causes of death. One of the causes of death for which excess female mortality is suspected is measles. METHOD: Sex differences in measles mortality are investigated using all national data on causes of death published by WHO since 1950. An index of excess mortality is used: the geometric mean of the female sex ratios of age-specific deaths rates from measles, from age 0 to 44 years. RESULTS AND CONCLUSIONS: When pooled together, the results show an excess of female mortality from birth until age 50 years. The excess female mortality appears small at age 0-4 (+4.2%), larger at age 5-14 (+10.9%) and peaks during the female reproductive period, at age 15-44 (+42.6%). This pattern of excess female mortality occurs in all the major regions of the world: Europe, North and South America, Far-East Asia, the Middle East and South Asia. The only noticeable exceptions are the Philippines and Thailand. The validity of the finding is extensively reviewed. Emphasis lies on the statistical power to prove that sex differences in measles mortality do exist, on the critical analysis of a case study in England and Wales, on the comparison with the overall pattern of sex differences and on available data on sex differences in incidence. Possible explanations are reviewed.

Adolescent↗

PubMed1983

In vitro attachment of Escherichia coli to human uroepithelial cells: variation in receptivity during the menstrual cycle and pregnancy.

An in vitro system was used for assay of the attachment of Escherichia coli to viable uroepithelial cells harvested from the urine of premenopausal women. A 15% level of variation from the mean attachment value was noted within given cell samples. Uroepithelial target cells with large numbers of adherent bacteria were found. The receptivity of uroepithelial cells to the attachment of certain strains of E coli varied over the menstrual cycle and during pregnancy. This finding may suggest that adult women are more susceptible to urinary tract infection at particular times during their reproductive period. Double-staining techniques were used for the detection of bacterial attachment to mucopolysaccharide-coated and non-mucopolysaccharide-coated uroepithelial cells. The level of attachment of one strain of E coli was higher when cells were mucus coated, while the attachment of a second strain was unaffected by the presence of a mucus coat. The results suggest the existence of at least two different mechanisms whereby E coli attaches to uroepithelial cells.

Adhesins, Escherichia coli↗

PubMed2003

The risk of maternal nutritional depletion and poor outcomes increases in early or closely spaced pregnancies.

An adequate supply of nutrients is probably the single most important environmental factor affecting pregnancy outcome. Women with early or closely spaced pregnancies are at increased risk of entering a reproductive cycle with reduced reserves. Maternal nutrient depletion may contribute to the increased incidence of preterm births and fetal growth retardation among these women as well as the increased risk of maternal mortality and morbidity. In the past, it was assumed that the fetus functioned as a parasite and withdrew its nutritional needs from maternal tissues. Studies in both animals and humans demonstrate, however, that if the maternal nutrient supply is inadequate, the delicate balance between maternal and fetal needs is disturbed and a state of biological competition exists. Furthermore, maternal nutritional status at conception influences how nutrients are partitioned between the mother and fetal dyad. In severe deficiencies maternal nutrition is given preference; in a marginal state the fetal compartment is favored. Although the studies of nutrient partitioning have focused on energy and protein, the partitioning of micronutrients may also be influenced by the maternal nutritional status. Marginal intakes of iron and folic acid during the reproductive period induce a poor maternal status for these nutrients during the interpregnancy interval. Poor iron and folic acid status has also been linked to preterm births and fetal growth retardation. Supplementation with food and micronutrients during the interpregnancy period may improve pregnancy outcomes and maternal health among women with early or closely spaced pregnancies.

Adolescent↗

PubMedDate not supplied

A model for evaluating the effect of son or daughter preference on population size.

This paper develops a micro probabilistic model to describe the family extension process. The parameters are: the probability that a newborn is a boy (P), the number of desired boys (B), the number of desired girls (G), and the maximum possible number of children (N). This maximum is a stopping rule rather than a biological maximum. The variables are the ultimate number of boys and girls. According to this model, each couple determines B, G, and N, at the beginning of the reproductive period and continues to reproduce until at least B and at least G are achieved, or until the total number of children reaches N. The probability distribution of the ultimate number of boys and girls in the population is derived for this model. Simulation techniques are used to generate offspring. The results showed that the population size increases with the absolute differences, [B-G] for fixed N. They also suggested that son or daughter preference may be an important factor in fertility determinants, which may have important implications in population policies.

Computer Simulation↗

PubMed1996

Comparison of the clinicopathological characteristics of premenopausal and postmenopausal endometrial carcinomas: analysis of endocrinologically evaluated cases.

A study was performed to clarify the clinicopathological differences between premenopausal endometrial carcinoma, which occurs during the reproductive period, and postmenopausal endometrial carcinoma. We analyzed 76 patients with endometrial carcinoma treated in our department between January 1984 and July 1994. Using classification criteria which included menstrual history and results of endocrinological tests (serum FSH, LH and estradiol), 50 (65.7%) patients were defined as postmenopausal, 16 (21.0%) as premenopausal, and 10 (13.1%) as unclassified. From an epidemiologic viewpoint, the incidence of nulliparity was higher in the premenopausal (37.5%) than in the postmenopausal (10%) patients. However, no significant differences were observed between the two groups with regard to the incidence of obesity, diabetes and hypertension. The results of our clinicopathological study revealed that premenopausal endometrial carcinoma had a significantly higher incidence of well differentiated (63.1%) and relatively less advanced (31.1% of cases at stages III and IV) cancers than postmenopausal carcinoma (38% and 46%, respectively). These features were positively correlated with prognosis, i.e., premenopausal patients in general had a much better prognosis than postmenopausal patients.

Adult↗

PubMed2005

Changes in egg production rate induced by progesterone injection in broiler breeder hens.

A polycystic ovarian follicle (PCOF) syndrome associated with high baseline concentrations of progesterone (P4) without preovulatory luteinizing hormone (LH) surges has been reported in turkey hens. The PCOF syndrome could be induced in turkey hens by injecting P4 (0.33 mg/kg per d) daily early in the reproductive period for 10 to 12 d and then waiting 3 wk for the syndrome to develop. It was hypothesized that an arrest in laying associated with the PCOF syndrome could be induced by daily injection of P4 in restricted-fed broiler breeder hens. Hens were divided into 5 treatment groups and were injected subcutaneously daily with P4 in canola oil at dosages of 0, 0.17, 0.33, 0.5, and 1.5 mg/kg per d for 13 d, at 14 wk of egg production when they were 41 wk of age. Blood samples were collected on d 7 and 13 immediately before P4 injection. Oviductal and ovarian morphologies were measured at necropsy 1 d after the last P4 injection. Egg production rate was reduced by injection of P4 at dosages < 0.17 mg/kg per d. At dosages of 0.5 and 1.5 mg/kg per d, ovarian hierarchical follicles had regressed. None of the broiler breeder hens had the PCOF syndrome at necropsy, but a high incidence of hens holding hard-shelled uterine eggs for several days was observed. Concentrations of LH decreased with P4 injection at > 0.17 mg/kg per d, and P4 concentrations were increased with P4 injection at > 0.5 mg/kg per d. Estradiol-17beta (E2) concentrations were decreased at all P4 dosages. It was concluded that egg production rate was reduced by daily injection of P4 at dosages > 0.17 mg/kg per d, and egg production ceased and ovarian follicles and the oviduct regressed at dosages > 0.50 mg/kg per d. The PCOF syndrome, however, was not induced in restricted-fed broiler breeder hens by P4 injection.

Animals↗

PubMed1994

Normal and abnormal mitoses in the atypical endometrial change associated with chorionic tissue effect [corrected].

The presence of mitotic figures was investigated in 215 cases of florid atypical endometrial change associated with chorionic tissue effect. Mitoses were found in 13.4% of the cases. Mitoses were occasionally observed in 10.2% of cases, and they were multiple in single microscopic fields in 2.7%. Abnormal mitoses were noted in 3.2% of the cases. The occurrence of normal and abnormal mitoses was mainly related to the early secretory type of abnormality. These observations have biologic implications, but of more practical interest, they indicate that the presence of mitoses per se are an insufficient criteria for the diagnosis of clear-cell carcinoma, particularly in women during their reproductive period.

Adult↗

PubMed1997

Auditory projections from the IC to the SCN by way of the LG in the mole, Mogera.

To study morphological substrates for sensory specialization in subterranean mammals, we investigated both auditory and visual pathways in the mole. The inferior colliculus (IC), an auditory relay, projects not only to the medial geniculate, the major gateway to the auditory cortex, but also to the lateral geniculate (LG), the major gateway to visual cortex. Further evidence is that the LG does not send many fibers to the cortex in the mole. Instead, the auditory inputs to the LG are likely to be conveyed to the suprachiasmatic hypothalamic nucleus (SCN), which plays a role in photoperiodic functions in common mammals. Auditory inputs to the SCN may subserve periodic reproductive behaviors in the exclusively separated territorial domains of subterranean mammals.

Animals↗

PubMed1978

Evaluation of single-stitch tubal ligation in postpartum women.

Permanent contraception by tubal surgery on completion of the family unit is increasingly becoming acceptable to younger women. Contraception by spacing methods during the long span of the reproductive period is impractical because of the cost involved, the fear of failure, and the possibility of side effects. Reversal of tubal surgery may be necessary in some young women as a result of unforseen infant deaths. Old and new techniques of tubal surgery,with or without endoscopy, still require the interruption of a long segment of the tubes (more than 1 cm) except in the spring-clip method, in which only 4 mm of tube is involved. These clips are expensive and not easily available. In a study of 463 women, the clip method was replaced by a single-stitch method to interrupt a small segment (1 mm) of the tubes. However, 24 failures occurred in the 230 women followed for a period of 6-36 months. In view of the high failure rate, use of this method was discontinued. This experience demonstrates that methods causing minimal tubal damage and providing maximum potential reversibility have greater risk of failure.

Evaluation Studies as Topic↗

PubMed1999

Cryptic female choice: frogs reduce clutch size when amplexed by undesired males.

In species with internal fertilization, females can 'cryptically' choose (e.g. through sperm selection) which individuals sire their offspring, even when their overt preferences for copulatory partners are overrun by male-male competition and sexual coercion. The experiment presented here reveals that control of paternity after copulation has begun is also possible in species with external fertilization. Females of the hybridogenetic Rana essonae-Rana esculenta (LL-LR) waterfrog complex adjust their clutch size in response to mate type: they release fewer eggs when amplexed by hybrid LR males who--jeopardize successful reproduction--than when amplexed by parental LL males. This reduction in the number of eggs laid can increase a female's residual reproductive value through a second mating in the same breeding season or a larger clutch size in the next year. We argue that cryptic female choice through clutch size adjustment (i) may have evolved more often than previously assumed, and (ii) can arise even where females mate only once during a reproductive period.

Animals↗

PubMed2005

Skuas at penguin carcass: patch use and state-dependent leaving decisions in a top-predator.

Foraging decisions depend not only on simple maximization of energy intake but also on parallel fitness-relevant activities that change the forager's 'state'. We characterized patch use and patch leaving rules of a top-predatory seabird, the Brown Skua (Catharacta antarctica lonnbergi), which during its reproductive period in the Antarctic establishes feeding territories in penguin colonies. In feeding trials, we observed how skuas foraged at penguin carcass patches and analysed patch leaving decisions by incorporating the estimated state of foraging birds and patch availability. Patches were exploited in a characteristic temporal pattern with exponentially decreasing remaining patch sizes (RPSs) and intake rates. Patch size decreased particularly fast in small compared to large patches and exploitation ended at a mean RPS of 47.6% irrespective of initial size. We failed to identify a measure which those birds equalized upon patch departure from raw data. However, when accounting for the birds' state, we ascertained remaining patch size and intake rates to have the lowest variance at departure whereas food amount and feeding time remained variable. Statistical correction for territory size only and combined with state had lower effects, but remaining patch size remained the measure with lowest coefficient of variation. Thus, we could clearly reject a fixed-time or fixed-amount strategy for territorial skuas and rather suggest a state-dependent strategy that equalizes remaining patch size. Thus our results provide evidence that under natural conditions, territorial skuas adjust their foraging decision on actual energy requirements, i.e. offspring number and age.

Animals↗

PubMed1986

Utilization of Previously Accumulated and Concurrently Absorbed Nitrogen during Reproductive Growth in Maize : Influence of Prolificacy and Nitrogen Source.

A prolific maize (Zea mays L.) genotype was grown to physiological maturity under greenhouse conditions to examine the effects of reproductive sink demand on (a) the remobilization of N accumulated during vegetative growth, and (b) the partitioning of N accumulated concurrent with ear development. One- and two-eared plants were treated with either a NO(3) (-) or NH(4) (+) source of (15)N-labeled N during reproductive growth. Plants with two ears enhanced grain production, N remobilization from the stalk and roots, and N translocation to the grain from concurrently assimilated N. But, remobilization of leaf-N was unaffected by ear number. In addition, N uptake and total dry matter accumulation during the reproductive period were also unaffected, although P uptake was greater in the two-eared plants. Less than 15% of the total K(+) uptake was accumulated after silking while during this time more than 40% of the total N and more than 50% of the total P were absorbed. The data also indicate that with NO(3) (-) nutrition, internal recirculation of K(+) between shoots and roots may play a prominent role in the transport of nitrogenous solutes during grain development. N source had no effect on dry matter production and N uptake of both one- and two-eared plants. However, slightly greater partitioning of labeled-N from the NH(4) (+) source to the grain was observed in the two-eared plants.

Journal Article↗