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Results for “Reproductive Period”

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PubMed2001

Dietary restriction and aging: comparative tests of evolutionary hypotheses.

Dietary restriction (DR) increases life span in many types of animals. The response to chronic DR may be an adaptation to environments with variable food levels. This study uses the comparative method to test evolutionary predictions about the origin of the response to DR, using data from 10 species of rotifers. Most species, but not all, responded to DR by increasing mean life span, maximum life span, reproductive life span, mortality rate doubling time, and initial mortality rate. Interspecific comparisons did not show the predicted correlations between the strength of the response to DR and either reproductive life span, age of first reproduction, or total reproduction. There was support for the idea that the response to chronic DR is associated with changes in reproductive allocation during short-term periods of starvation: species that reduced reproduction when starved increased their life spans under DR, whereas species that continued to reproduce when starved decreased their life spans under DR.

Aging↗

PubMed1993

Family planning: cultural and religious perspectives.

The world population explosion has caused political leaders to look upon national and regional birth control projects as vital. Support for regulation of individual fertility has been evident in all cultures, and at all times, even in those societies in which social and religious rules have favoured the abundant production of children. As the secularization of Western society and scientific enquiry gained momentum during the modern period, knowledge of reproduction increased and was applied to control human population growth. The various methods of contraception and their development through the years from the ancient ideas to the modern era are presented. Each approach to fertility control has its advantages and disadvantages. No one method is perfect for everyone, for every clinical setting, and in every culture. Higher levels of fertility have been associated with 'traditional', religious prohibitions on some forms of birth control, 'traditional' values about the importance of children and the priority of family, and 'traditional' family and gender roles reinforced by religion. The attitude of the main religious groups to contraceptive practice is discussed.

Contraception↗

PubMed1992

In vitro prostaglandin release from and platelet-activating factor accumulation in isolated endometrial cells from pregnant and pseudopregnant rabbits.

Prostaglandin (PG) release from and platelet-activating factor (PAF) accumulation by enzymatically isolated endometrial epithelial and stromal cells from Day 6 pregnant and Day 6 pseudopregnant rabbits were studied in vitro, using RIA for PG measurement and a platelet aggregation assay for PAF measurement. On the first day of culture in serum-free media, PGF release into the medium was significantly higher from epithelial cells from Day 6 of pregnancy than from stromal cells from Day 6 of pregnancy or pseudopregnancy. PGE release did not differ significantly among these cell types. The addition of indomethacin (10(-5) M) to similar cultures inhibited release of both PGs from both cell types, but to a much greater extent from stromal than from epithelial cells. Significant stimulation of PG release by A23187 was achieved under all conditions on the fifth day of culture; PGE release was significantly greater than PGF release from stromal cells from Day 6 of pregnancy and pseudopregnancy, and release of both PGs from stromal cells was significantly greater from Day 6 of pregnancy than from Day 6 of pseudopregnancy. PG release from similar cells, cultured in medium containing 10% calf serum, was highest on the first or second day of culture and then, especially for PGF, declined with continued culture. PGE release was significantly higher than PGF release from stromal cells on the third and fourth days of culture. The ratios of PGF/PGE release from epithelial cells were significantly higher than those from stromal cells over the 5-day culture period for both reproductive stages. These ratios indicate the differential release of PGE and PGF from rabbit endometrial cell subpopulations and indicate a preferential release of PGE from stromal and of PGF from epithelial cells. Under basal conditions, PAF was not detected in epithelial or stromal cells cultured for 2 or 4 days, or in the associated culture media. If PAF had been released into the medium, it would have rapidly metabolized. Short exposure to calcium ionophore A23187 (10(-5) M) was able to stimulate PAF accumulation in epithelial and stroma cells in serum-free media, probably via the remodeling pathway. PAF was not detected in the medium. Intracellular PAF accumulation after exposure to A23187 (10(-5) M) for 5 min was significantly greater on the second day of culture than on the fourth day in epithelial and stromal cells from Day 6 of pregnancy.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1986

Hysteroscopic treatment of the septate uterus.

Twelve patients with symptomatic septate uteri underwent hysteroscopic division of the uterine septum, monitored by concomitant laparoscopy, over a six-year period. The preoperative reproductive performance included 42 pregnancies, with only three viable deliveries. Ten of the 12 patients conceived within one year after therapy, and eight of these patients delivered a live infant at term. Two patients had a spontaneous abortion at six and eight weeks after therapy, respectively, but in each, a subsequent pregnancy was carried to term. Three patients are currently pregnant (eight, 12, and 18 weeks). Two patients have not as yet conceived. Two patients required a second hysteroscopic operation because a partial residual septum was observed on the posttreatment hysterogram.

Abortion, Habitual↗

PubMed1997

Genotypic variation among different phenotypes within aphid clones.

Most aphid species Hemiptera: Aphididae are parthenogenetic between periods of sexual reproduction. They are also highly polyphenic, with different adult morphs occurring in the life cycle, piz. winged, wingless, asexual and sexual. It is assumed that aphids born in a parthenogenetic clonal lineage are genetically identical regardless of the final adult form with the exception of sexual forms). Using the randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) we have found that different asexual adult phenotypes winged and wingless of some clones of two cereal aphid species (the grain aphid, Sitobion avenae (F.) and the bird-cherry aphid. Rhopalosiphum padi (L.) may be distinguished by the presence or absence of one or more RAPD-PCR bands. In three of nine clones examined, such differences were found, and Southern blotting and hybridization of the discriminating bands confirmed these to be of aphid origin, rather than due to endosymbiotic bacteria or contaminating fungi. The main 248 and 296 bp bands, in the two species respectively, were sequenced and found to be A/T rich. The smaller band showed 57% homology with white striated muscle over a stretch of 90 bp. Genomic DNA treated with dimethyl sulphoxide to remove secondary structures still showed differences in RAPD-PCR profiles between winged and wingless morphs within the unusual clones. This discovery may be widespread and therefore it is important to understand the phenomenon in relation to clonal organisms.

Animals↗

PubMed1999

An uncoupling of male and sexual egg production leads to reduced inbreeding in the cyclical parthenogen Daphnia

Cyclical parthenogenesis involves an alternation of parthenogenetic and sexual reproduction. In cyclical parthenogens with a short generation time, seasonal succession of clones switching to sexual reproduction at different periods of the growing season entails the risk of severe inbreeding with associated fitness costs. We show, however, that differences in genotype frequencies between males and sexual females result in a substantial reduction in the probability of selfing in natural Daphnia populations. This suggests that responses to male- and sexual egg-inducing stimuli may be uncoupled at the level of individual clones as a mechanism to avoid severe inbreeding.

Journal Article↗

PubMed1998

Salt overload does not modify plasma atrial natriuretic peptide or vasopressin during pregnancy in rats.

The present study was carried out to determine whether the increased salt intake induce by increased specific sodium appetite in pregnant rats modifies water-salt homeostasis throughout pregnancy. Two groups of pregnant rats were used, one fed ad libitum with a normal sodium (NS) diet consisting of standard rat chow and distilled water, and the other fed with a high-sodium (HS) diet with free access to chow, distilled water plus saline solution (1.5% NaCl). Virgin rats in dioestrus were also studied as non-pregnant controls. Pregnant animals were studied on days 4, 9, 14, 20 and 21 of gestation at which time body weight, water and saline intake, sodium excretion, plasma atrial natriuretic peptide (ANP) and arginine vasopressin (AVP) concentrations, as well as plasma osmolality were determined. Data showed that water intake was higher in the NS group, but total fluid intake (water plus saline) was higher in the HS group throughout pregnancy. Dietary sodium intake was the same for both groups but total sodium intake (chow plus saline) was 60-98% higher in the HS rats. Pregnant HS rats excreted more fluid (35-50%) and sodium (up to 100%) compared with NS rats, indicating that the animals could change their renal excretion in response to a 2.5-fold higher dietary sodium intake compared with the control level. Salt satiety during pregnancy did not modify plasma ANP concentration. In both groups of pregnant rats ANP levels increased 3-fold on day 14 without significant alteration in sodium excretion, suggesting that the natriuretic action of ANP is attenuated at least after the second week of pregnancy. High sodium intake did not change plasma AVP concentration or osmolality and both groups showed the same gradual decrease in plasma osmolality (approximately 8 mosmol kg-1) at the end of pregnancy that was not accompanied by decreased plasma AVP concentration. The present data show that rats maintain the special homeostatic equilibrium that occurs in normal pregnancy even when they are allowed to increase sodium intake to satisfy their salt appetite during this period of the reproductive cycle.

Animals↗

PubMed1975

Environmental modification of western equine encephalomyelitis infection in the snowshoe hare (Lepus americanus).

The snowshoe hare (Lepus americanus) could be infected with western equine encephalomyelitis (WEE) virus and produce a viremia. Furthermore, viremia in hares exposed to variable climatic conditions differed significantly from viremias seen in the control animals held at constant temperatures. The viremia duration and titer were increased in animals subjected to fluctuating temperature and humidity. The time of onset of viremia was accelerated. Antibody response also increased in animals exposed to varying temperatures when compared with controls held at constant temperature and humidity. Snowshoe hares were studied at two distinct seasonal periods: winter, before reproductive activity; and summer, during reproductive midseason. Winter animals experienced greater viremia than did summer hares when exposed to fluctuating temperatures, suggesting a seasonality in the hare's susceptibility to host modification by environmental influences. These findings implicate the snowshoe hare as a possible mammalian amplifying host for WEE virus in the boreal forest.

Animals↗

PubMed2005

New antiviral drugs, vaccines and classic public health interventions against SARS coronavirus.

Severe acute respiratory syndrome (SARS) is caused by one of two recently discovered coronaviruses. The virus is emergent from South East (SE) Asian mammals: either the civet cat, a related species or a rat species. The virus has a long incubation period and low reproduction number (R0 value) and hence the first outbreak in 2004 was controlled by hygiene and quarantine. However, the healthcare system was compromised and the economic cost was extremely high. Fortunately, the virus is easily cultivated in Vero E6 cells and therefore the search for new antivirals and vaccines was initiated within weeks of the discovery of the virus using classic techniques of cell culture and electron microscopy. Molecular diagnostics facilitated rapid and accurate diagnosis, a key factor in containing the outbreak. The broad-spectrum molecule ribavirin was used in SE Asia in infected patients alongside corticosteroids. In retrospect, many patients survived due to careful nursing. The only currently accepted intervention is interferon. Coronavirus replicon systems should facilitate rapid screening of new inhibitors and the complex mechanism of viral replication will ensure that drugs are developed against at least five molecular targets, in particular the viral protease.

Animals↗

PubMed2006

Gonadotropin-releasing hormone-II messenger ribonucleic acid and protein content in the mammalian brain are modulated by food intake.

GnRH-II is the most evolutionarily conserved member of the GnRH peptide family. In mammals, GnRH-II has been shown to regulate reproductive and feeding behaviors. In female musk shrews, GnRH-II treatment increases mating behaviors and decreases food intake. Although GnRH-II-containing neurons are known to reside in the midbrain, the neural sites of GnRH-II action are undetermined, as is the degree to which GnRH-II is regulated by energy availability. To determine whether GnRH-II function is affected by changes in food intake, we analyzed the levels of GnRH-II mRNA in the midbrain and GnRH-II protein in numerous target regions. Adult musk shrews were ad libitum fed, food restricted, or food restricted and refed for varying durations. Compared with ad libitum levels, food restriction decreased, and 90 min of refeeding reinstated, GnRH-II mRNA levels in midbrain and GnRH-II peptide in several target areas including the medial habenula and ventromedial nucleus. Refeeding for 90 min also reinstated female sexual behavior in underfed shrews. In male shrews, abundant GnRH-II peptide was present in all sites assayed, including the preoptic area, a region with only low GnRH-II in females. In contrast to females, food restriction did not affect GnRH-II protein in male brains or inhibit their mating behavior. Our results further define the relationship between GnRH-II, energy balance, and reproduction, and suggest that food restriction may inhibit female reproduction by reducing GnRH-II output to several brain nuclei. We postulate that this highly conserved neuropeptide functions similarly in other mammals, including humans, to fine-tune reproductive efforts with periods of sufficient energy resources.

Animals↗

PubMed1985

Cellular changes in the spleen during an induced molt.

Agranulocytes proliferated in spleens of molted hens and both leucocytic and erythrocytic cells exhibited decreased numbers of pyknotic nuclei. These changes were confined to the period when the reproductive tract regressed. It was concluded that there is a relationship between the physiological status during an induced molt and the cellular population of the spleen.

Animals↗

PubMed2000

[Vocal tract disorders in women with hormonal gynecological diseases].

The paper analyzes the incidence rates and specific features of vocal apparatus disorders in dyshormonal gynecological diseases in the reproductive and menopausal periods. It presents a complex procedure for diagnosis and treatment, which includes the management of the patient by a phoniatrist jointly with an endocrinological gynecologist, a psychoneurologist, and a phonopedist. Drugs for correcting sexual hormone levels, psychoemotional status, venous tone, breathing exercises and phonopedic classes by using biological feedback, and physiotherapeutical methods of treatment have been used. Indications and contraindications for the use of hormonal drugs in the treatment of dyshormonal gynecological diseases in individuals of voice-and-speech professions are considered.

Adult↗

PubMedDate not supplied

[Effect of the elevated temperature on sex ratio in population of hog slaters (Asellus aquaticus L.)].

Seasonal changes in the abundance and sex ratio in the hog slater were monitored in nature throughout the annual cycle. It was shown that the sex ratio was balanced at a relatively low abundance in the autumn-winter period. The number of males could exceed 1.5-fold that of females during the period of mass reproduction in spring and summer. The experimental results suggest that the summer shift of sex ratio towards males was due to their higher tolerance to elevated temperature at the early ontogenetic stages.

Animals↗

PubMedDate not supplied

Causes of sow mortality in Hungarian indoor and outdoor pig production units.

Assessing the reasons for death in pig breeding units is the first step in understanding and controlling the factors influencing sow losses due to mortality. From October 1997 to October 2001 in forty-nine indoor (2876 sows died) and sixty-five outdoor breeding units (3451 sows died) sow mortality was evaluated. The average annual mortality rate during the four year evaluation period was 5.1 +/- 1.2% in indoor and 12.2 +/- 2.1% in outdoor production units. Swine urogenital disease (SUGD, 32.4%), heart failure (HF, 21.8%) and locomotor problems (LP, 33.1%) caused deaths were markedly higher in outdoor production, while periparturient diseases (mastitis-metritis-agalactia, MMA, 24.5%) and torsion or distension abdominal organs (TDA, 20.5%) revealed markedly higher losses in indoor units. The annual culling rate was 39.1% in the indoor and 45.2% in the outdoor units. In outdoor units 40.1% of all deaths occurred during the periparturient period of the reproductive cycle, in indoor units the majority of mortality happened during lactation (40.2%). Average parity at death was 3.6 in indoor and 2.5 in outdoor production.

Animal Husbandry↗

PubMedDate not supplied

[Adaptation to new environments: microgravity].

Review and analysis of the experiments with Wastar rats in microgravity onboard "Cosmos" biosatellites allows to conclude that adaptive potentials of mammals in space flights lasting up to 1/50 th of their life span are enough for rapid elimination of microgravity-induced metabolic and structural alterations on return to Earth, for maintenance of adequate reactions to acute and chronic stressors in the post-flight period, for normal reproductive function and life span. Consideration is given to individual differences in body responses to the micro-g environment.

Adaptation, Physiological↗

PubMed1992

Current status of in vitro fertilization and the new reproductive technologies.

The rapid pace of development and refinement of in vitro fertilization and ancillary assisted reproductive techniques warrants periodic review to keep the reader abreast of the growth in this clinical and scientific arena. Although not exhaustive, this review targets key areas of special interest and significance, including oocyte and embryo micromanipulation for assisted fertilization and genetic analysis, advances in the approach to ovarian stimulation, and examination of the scientific model afforded by ovum donation.

Female↗

PubMed1975

The effect of supraoptimal temperature on the multiplication of different cytomegalovirus strains.

The virion synthesis by five human cytomegalovirus (CMV) strains in human embryonic fibroblast cultures was stopped by incubation of the infected cultures at 40 degrees C. At this temperature the antigens appeared diffusely filling the nucleus and the cytoplasm. The blocking effect of the elevated temperature was exerted in the same period of the reproduction cycle as the inhibitory effect of cytosine arabinoside (ara-C). In cell cultures infected with CMV and incubated first at 40 degrees C, then at 37 degrees C, the synthesis of infectious virus started again, thus the abortive cycle developed at 40 degrees C was reversible. The inhibition of virus multiplication cannot be attributed to the thermosensitive events in the normal function of the host cell.

Antigens, Viral↗

PubMed1991

A prospective study of sow mortality in breeding herds.

This investigation was conducted to study the incidence and the causes of sow mortality in breeding herds. Data were obtained from 24 swine breeding herds with an average inventory of 3755 sows and served gilts for the total sample. Producers were involved for 12 consecutive months and agreed to submit to the diagnostic laboratory every dead or moribund sow and served gilt. The average herd death rate was 3.3% +/- 0.5 (SEM), but varied considerably among herds, ranging from 0% to 9.2%. A total of 137 sows and mated gilts died during the year, and these females had produced an average of 4.2 litters +/- 0.2 (SEM). The number of deaths was significantly higher during the months of July, August and October. The peripartum period appeared to be when sows were most at risk, with 42% of all deaths occurring during this short period of the reproductive cycle. The three major causes of death were heart failure (31.4%), torsions and accidents of abdominal organs (15.3%) and cystitis-pyelonephritis (8.0%). Other causes included endometritis (6.6%), uterine prolapses (6.6%), pneumonia (3.6%), gastric ulcers (3.6%), downer sow syndrome (2.2%), miscellaneous (8.0%) and unknown (14.6%).

Animals↗