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Results for “Reproductive parameters”

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PubMed1987

The effect of seasonal temperature and experimental illumination on reproductive rate in the snail Biomphalaria glabrata.

1. Reproduction in the snail Biomphalaria glabrata, a vector of Schistosoma mansoni, was measured by egg production and other parameters such as number of clutches, eggs per clutch and egg hatching, under laboratory conditions. 2. Reproductive rates were highest in terms of total number of eggs, clutches and hatching under constant illumination, followed by conditions similar to the natural rhythm of illumination. The greatest reduction in reproduction occurred in constant darkness. In summary, reproductive rate was dependent on both the intensity of absolute illumination and the schedule of illumination exposure. 3. Seasonal variation in reproductive rate appeared to vary inversely with local temperature in Belo Horizonte, situated in a tropical zone (latitude 20 S) owing probably to a temperature preference of 20 to 25 degrees C by the snail. The highest reproductive rates occurred in winter, except for the parameter eggs per clutch which was maximal in autumn. Snail reproduction appeared to be most reduced during summer. There was no linear correlation between reproductive rate and temperature.

Animals↗

PubMed2005

Effect of partial charge parametrization on the fluid phase behavior of hydrogen sulfide.

The effect of partial charge parametrization on the fluid phase behavior of hydrogen sulfide is investigated with grand canonical histogram reweighting Monte Carlo simulations. Four potential models, based on a Lennard-Jones + point charge functional form, are developed. It is shown that Lennard-Jones parameters can be tuned such that partial charges for the sulfur atom in the range -0.40 < q(s) < -0.252 will lead to an accurate reproduction of experimental vapor-liquid equilibria. Each of the parameter sets developed in this work are used to predict the pressure composition behavior H2S-n-pentane at 377.6 K. While the mixture calculation provides a means of reducing the number of candidate parameter sets, multiple parameter sets were found to yield an excellent reproduction of both the pure component and mixture phase behavior.

Journal Article↗

PubMed1992

Menstrual-cycle characteristics and work conditions of workers in poultry slaughterhouses and canneries.

The food and agriculture industry employs 14.6% of the female industrial work force in France. Workers are exposed to a variety of environmental and organizational constraints (eg, irregular schedules, cold, uncomfortable postures, repetitive movements). In 1987-1988 a medical examination and questionnaire were administered to 726 workers with menstrual periods in 17 poultry slaughterhouses and six canning factories. Anomalies (irregular cycles, amenorrhea, long cycles) during the previous year were associated with work conditions. After adjustment for relevant nonoccupational variables, irregular cycles were significantly related to schedule variability and cold exposure, amenorrhea was associated with cold exposure, and long cycles with schedule variability. Other parameters such as repetitive work, standing posture, lifting weights, job satisfaction, and hours of domestic work were not associated with cycle anomalies. Cycle anomalies may be a useful indicator of occupational effects on female reproduction, analogous to the use of sperm parameters to warn of effects on male workers.

Abattoirs↗

PubMedDate not supplied

[Reproductive outcome of hysteroscopic lysis of intrauterine adhesions].

OBJECTIVE: To analyze the reproductive outcome in women undergoing hysteroscopic lysis of intrauterine adhesions, according to their localization and severity. STUDY DESIGN: Retrospective study. MATERIALS AND METHODS: Fifty-three patients affected by intrauterine adhesions of different degree, subdivided according to localization and morphologic aspect: three isthmic, thirteen marginal, fourteen central, moreover twenty were complex and three complete. All the interventions were performed by means of the resectoscope. RESULTS: Hysteroscopic surgery restored an acceptable menstrual cycle in almost all the patients affected by intrauterine isolated adhesions, in 52% of women affected by complex incomplete adhesions, and in none of the three patients with entirely obliterated cavity. Concerning fertility, while in isolated, isthmic, central or marginal synechias we observed a pregnancy rate of 73.3% (22 out of 30) with a pregnancy rate to term respectively of 63.3% (19 out of 30 cases) and of 86.3% (19 out of 22 total pregnancies), in case of complex but not complete adhesions we reported, on 20 cases, 5 pregnancies (25%) with only two gone to term. We had no pregnancy in three cases of complex synechias. CONCLUSIONS: The basic parameter to define the functional and reproductive prognosis of the hysteroscopic lysis of intrauterine adhesions is not the menstrual profile or the histological characteristic of the lesions, but rather their extension.

Adult↗

PubMed2003

Food quality controls reproduction of the zebra mussel (Dreissena polymorpha).

Species such as Dreissena polymorpha sometimes contribute substantially in the transfer of primary to secondary production. During the ontogenetic cycle, the reproductive investment of adult mussels is one of the main parameters that affect recruitment success. We studied how food quality and temperature affect the reproductive investment in term of egg mass of D. polymorpha in a lake by sampling mussels monthly from 4 m and 15 m depths. Temperature affected reproduction directly and also indirectly through the food. To assess whether temperature and/or food conditions led to the differences observed in mussels sampled from the two depths, mussels were reared in the laboratory under two different temperature regimes for 3 months, simulating the temperature of the lake at 4 m and 15 m depth. Possible effects of food quality were tested at each temperature using four diets differing in fatty acid composition. Temperature played an important role as a trigger for spawning, and the type of diet clearly affected the reproductive investment. When the heterokont chromophyte alga Nannochloropsis limnetica, which is rich in polyunsaturated fatty acids (PUFAs) and long-chained PUFAs (>C18), was fed to mussels, an increased egg mass was obtained. This result was in contrast to that found when the green alga Scenedesmus obliquus and the cyanobacterium Aphanothece sp., both of which are deficient in long-chained PUFAs, were offered as food to the mussels. Such a PUFA-dependent food quality may affect reproduction in lakes. Food quality effects vary seasonally in a lake and may be most important in summer, when low-food-quality green algae and cyanobacteria are abundant. The low biochemical quality of these blooms may affect at least the later period of gametogenesis of D. polymorpha, which reproduces from June to August.

Animals↗

PubMed2000

Statistical inference on associated fertility life table parameters using jackknife technique: computational aspects.

Knowledge of population growth potential is crucial for studying population dynamics and for establishing management tactics for pest control. Estimation of population growth can be achieved with fertility life tables because they synthesize data on reproduction and mortality of a population. The five main parameters associated with a fertility life table are as follows: (1) the net reproductive rate (Ro), (2) the intrinsic rate of increase (rm), 3) the mean generation time (T), (4) the doubling time (Dt), and (5) the finite rate of increase (lambda). Jackknife and bootstrap techniques are used to calculate the variance of the rm estimate, which can be extended to the other parameters of life tables. Those methods are computer-intensive, their application requires the development of efficient algorithms, and their implementation is based on a programming language that encompasses quickness and reliability. The objectives of this article are to discuss statistical and computational aspects related to estimation of life table parameters and to present a SAS program that uses jackknife to estimate parameters for fertility life tables. The SAS program presented here allows the calculation of confidence intervals for all estimated parameters, as well as provides one-sided and two-sided t-tests to perform pairwise or multiple comparison between groups, with their respective P values.

Animals↗

PubMed2003

Using rotifer population demographic parameters to assess impacts of the degradation products from trinitrotoluene phytoremediation.

The objective of this study was to evaluate the chronic lethal and sublethal aquatic toxicity effects associated with the phytoremediation of water contaminated with 2,4,6-trinitrotoluene (TNT) by the wetland plant species Myriophyllum aquaticum (parrot feather). Rotifers (Brachionus calyciflorus) feeding on an algal species (Nannochloropsis spp.) were used as the aquatic test organisms. Continuous flow laboratory microcosms were used to quantify effects on rotifer populations from TNT and the primary degradation product aminodinitrotoluene (ADNT) during and after phytoremediation. Rotifer demographic parameters from life tables, including survivorship, fecundity, reproductive values, net reproductive rate, generation time, intrinsic growth rate, and life expectancy, were used as measures of treatment effects. High-performance liquid chromatography analyses were performed to determine nitroaromatic concentrations. Results from this study have revealed significant differences in rotifer demographic parameters between microcosms with elevated initial TNT concentrations. Significant differences in demographic parameters also existed between the microcosms that did and did not receive phytoremediation treatment and the control microcosms. Study results have indicated that TNT phytoremediation via artificial wetlands not only may clean up hazardous waste at munitions sites but also may encourage the growth of aquatic populations such as rotifers.

Algorithms↗

PubMedDate not supplied

The conduct of a two-generation reproductive toxicity study via dermal exposure in the Sprague-Dawley rat--a case study with KBR 3023 (a prospective insect repellent).

KBR 3023, 1-(1-methyl-propoxycarbonyl)-2-(2-hydroxyethyl)-piperidine, a prospective insect repellent being developed by the Bayer Corporation, was evaluated for reproductive toxicity in the Sprague-Dawley rat. As the intended human use of the test compound is topical, the test system was also exposed to the compound via the dermal route. Specifically, the adult rats (P generation) were fitted with Elizabethan collars, to reduce the likelihood of oral ingestion, and dermally administered either 0, 50, 100, or 200 mg KBR 3023/kg body weight throughout the study (5 d/week) beginning at the onset of the 10-week premating period and continuing through the mating, gestation, and lactation phases. Clinical signs and changes in body weight and food consumption were assessed throughout the study. All adults and neonates underwent a gross necropsy examination. Tissues retained for microscopic examination from all adult animals included the kidney, liver, pituitary, reproductive organs, and samples of skin from the shaved dose site. In addition to the parameters noted above, the animals were evaluated for the effect of the test compound on estrous cycling, mating, fertility, gestation length, litter size, pup sex ratio, and pup viability. There were no test compound-related clinical signs or effects on body weight or food consumption observed in either the adults or the pups during any phase of the study. There were no compound-related effects on any reproductive or litter parameters. Dermal findings at the dose site (acanthosis and hyperkeratosis) were noted in both generations. Other than the dermal findings, no compound-related necropsy findings were seen in either the adults or the pups. No compound-related histopathologic findings were noted in the reproductive tissues of either the males or females. Based on these results, KBR 3023, administered as described in this study at dose levels as high as 200 mg/kg body weight (the physical limit of dermal application for this compound), did not demonstrate any reproductive toxicity.

Administration, Topical↗

PubMed2001

The effect of a GnRH antagonist on endocrine and seminal parameters in stallions.

Relatively little is known about endocrine control of reproduction in the stallion, but gonadotropins are thought to be central in regulating spermatogenesis and libido. The ability to effectively antagonise GnRH, and thereby gonadotropins, is therefore important both in further investigations of hormonal control of reproduction in stallions, and for clinical applications. In the present study four pony stallions were treated with a potent GnRH antagonist, Antarelix. Their libido, seminal parameters, and hormonal profiles were compared with those recorded before administration of the antagonist. Plasma concentrations of gonadotropins, testosterone and estradiol decreased by 48 h after antagonist administration, with estradiol and FSH being most consistently suppressed, and remained at reduced concentrations for 4 weeks. Spermatozoal motility, numbers and morphology were not significantly affected by treatment, but increasing numbers of round spermatogenic cells were seen in the ejaculate as the trial progressed. Libido was assessed by the time taken for the stallions to regain an erection in the presence of a mare after ejaculation (refractory period). The refractory period increased significantly after treatment. When the stallions were castrated 8 weeks after antagonist treatment, histological evidence of testicular degeneration was present. We concluded that use of this antagonist showed promise as a valuable research tool in modulating changes in circulating hormone concentrations in stallions. Reversibility of the effects on libido and testicular changes need further investigation.

Animals↗

PubMed1999

Partial and generalized seizures affect reproductive physiology differentially in the male rat.

PURPOSE: Reproductive dysfunction and endocrine disorders occur frequently among men with epilepsy. This study tested the hypothesis that focal limbic seizures and generalized seizures may both contribute to reproductive dysfunction. METHODS: The rat kindling model was used to mimic focal limbic seizures. Kindling electrodes were placed in the basolateral amygdala. Male rats were either intact, gonadectomized (GDX) or GDX + testosterone (T) replaced and then kindled. Controls were left intact and sham-kindled. Maximal electroconvulsive shock (MES) treatment was used to model generalized seizures, by using eight stimulations, one every other day, for 2.5 weeks. Animals were killed either 3 h or 6 weeks after MES treatment to determine short- and long-term effects. RESULTS: Kindled seizures resulted in an increase in serum testosterone, estradiol, and prolactin in intact males, accompanied by a significant increase in testis, epididymis, and pituitary weight, as well as a significant decrease in prostate weight. MES treatment caused a short-term reduction in serum testosterone and testis, epididymis, and prostate weight. All parameters were restored to control values within 6 weeks of the last MES seizure, with the exception of pituitary weight and serum prolactin, which remained significantly elevated 6 weeks after MES treatment. CONCLUSIONS: Our results indicate that both focal limbic (amygdaloid) seizures and generalized MES seizures disturb normal reproductive physiology in the male rat. Amygdaloid-kindled seizures have mixed effects on different parameters of reproductive function, whereas MES seizures induce a transient hypogonadal state. These results suggest that reproductive dysfunction in men with epilepsy may result from seizure-related interference with the normal functions of the hypothalamic-pituitary-testicular axis.

Amygdala↗

PubMed1998

Infectivity and dynamics of HIV type 1 replication in the blood and reproductive tract of HIV type 1-infected women.

This article delineates several parameters that can influence compartmentalized virus shedding in relation to organ-specific factors and cofactors in the blood and reproductive tract compartments of women infected with the human immunodeficiency virus type 1 (HIV-1). Because a wide variety of techniques is currently used for the collection, processing, and quantitation of HIV load in the female genital secretions, standard protocols for appropriate sampling and testing of these specimens are provided. Studies conducted in our laboratory have shown that the levels of cell-free HIV-1 RNA in the female reproductive tract and the blood plasma within HIV-1-infected women are different and therefore may represent independent events.

Adolescent↗

PubMedDate not supplied

Estimating the basic reproductive rates of Neisseria gonorrhoeae and Chlamydia trachomatis: the implications of acquired immunity.

BACKGROUND AND OBJECTIVES: The basic reproductive rate of and STD is an important parameter from which the success of intervention strategies can be predicted. GOAL OF THE STUDY: To evaluate different methods to estimate the basic reproductive rate. RESULTS: Two different methods of estimating the basic reproductive rates of Neisseria gonorrhoeae and Chlamydia trachomatis yielded discrepant results. One of the methods, which is based on the assumption of the absence of acquired immunity, yielded unrealistically low estimates of the basic reproductive rates. CONCLUSION: In conjunction with other epidemiologic evidence, we infer that some form of acquired immunity to these pathogens must exist and discuss its implication for control.

Antibody Formation↗

PubMed1999

Discrete event versus continuous approach to reproduction in structured population dynamics.

The governing equations are derived for the dynamics of a population consisting of organisms which reproduce by laying one egg at the time, on the basis of a simple physiological model for the uptake and use of energy. Two life stages are assumed, the egg and the adult stage where the adults do not grow. These assumptions hold true, for instance, for rotifers. From the model for the life history of the individuals, a physiologically structured population model for a rotifer population is derived. On the basis of this discrete event reproduction population model a continuous reproduction population model is proposed. The population model together with the equation for the food result in chemostat equations which are solved numerically. We show that for the calculation of the transient population dynamic behaviour after a step-wise change of the dilution rate, an age structure suffices, despite the size and energy structure used to describe the dynamics of the individuals. Aggregation of the continuous reproduction population model yields an approximate lumped parameter model in terms of delay differential equations. In order to assess the performance of the models, experimental data from the literature are fitted. The main purpose of this paper is to discuss the consequences of discrete event versus continuous reproduction. In both population models death by starvation is taken into account. Unlike the continuous reproduction model, the discrete model captures the experimentally observed lack of egg production shortly after the step change in the dilution rate of the chemostat.

Age Factors↗

PubMed1992

Comparison of sublethal and lethal criteria for nine different chemicals in standardized toxicity tests using the earthworm Eisenia andrei.

In this study, the effects of nine different chemicals on the survival, growth, and reproduction of the earthworm species Eisenia andrei were determined using a recently developed method. Earthworms were exposed for 3 weeks to the test chemicals in an artificial soil substrate. Additional data on the acute toxicity of these chemicals were derived from the literature. For some chemicals, cocoon production was the most sensitive parameter (cadmium, chromium, paraquat, fentin, benomyl, phenmedipham), while for others cocoon hatchability was most sensitive (pentachlorophenol, parathion, carbendazim). In the case of parathion, growth of the worms seemed to be even more sensitive than reproduction. As an overall parameter for the effect on earthworm reproduction, the total number of juveniles produced per worm appeared to be a useful parameter. Differences between (acute) LC50 values and the lowest NOEC value for effects on growth and reproduction were different for each chemical. Difference was greatest for cadmium (a factor of greater than 100) and smallest for fentin, benomyl, and pentachlorophenol (a factor of 5-6).

Animals↗

PubMed1998

Interindividual variations in the disomy frequencies of human spermatozoa and their correlation with nuclear maturity as evaluated by aniline blue staining.

OBJECTIVE: To evaluate the importance of interindividual variations in the disomy frequencies of human sperm and their possible correlation with the principal semen parameters. DESIGN: Prospective randomized analysis of sperm nuclei by fluorescence in situ hybridization and analysis of semen parameters. SETTING: University-based laboratory for reproductive biology. PATIENT(S): Fifty-seven human ejaculates selected at random from a population of men undergoing semen analysis. INTERVENTION(S): Semen specimens were analyzed, and sperm samples were prepared for fluorescence in situ hybridization. MAIN OUTCOME MEASURE(S): Semen parameters, including necrozoospermia, global motility, sperm concentration, multiple abnormalities index, and teratozoospermia were evaluated, aniline blue staining was completed, and disomy frequencies for chromosomes 8, 15, 18, X, and Y were determined using fluorescence in situ hybridization. RESULT(S): Noticeable differences in disomy frequencies between individuals were observed, and these frequencies were correlated with the degree of nuclear maturity. CONCLUSION(S): We hypothesize that the positive correlation can be explained by an abnormality of chromosomal segregation at the time of meiosis that would cause disturbances during the transition of nucleoprotein or by one or several premeiotic abnormalities of chromatin that would perturb both the meiotic process and the construction of definitive proteins.

Adult↗

PubMed2026

Don't judge a sperm by its cover.

Male fertility is primarily assessed using descriptive semen parameters, such as sperm concentration, motility and morphology. These conventional parameters provide an initial assessment of male reproductive health and may explain why a couple is struggling to conceive; however, they are not a direct measure of fertility potential. Growing evidence suggests that spermatozoa transmit far more than paternal DNA. Alongside the genome, spermatozoa deliver proteins, RNA and epigenetic information that are responsive to environmental and lifestyle exposures, and can influence embryo development, pregnancy outcomes and offspring health. This emerging concept challenges the view that male fertility is defined solely by successful conception. Here, we discuss evidence that spermatozoa act as carriers of environmental and lifestyle 'memories', transmitting molecular information shaped by paternal health to the next generation. We further consider the implications for assisted reproductive technologies, which select spermatozoa largely on their capacity to move while overlooking the molecular cargo they transmit. Recognising spermatozoa as vectors of environmental information reframes male fertility and highlights the need for biomarkers that assess molecular integrity alongside conventional clinical parameters.

Male↗

PubMedDate not supplied

Sperm decondensation and semen parameters: utilization of a simple staining technique for the evaluation of human sperm decondensation.

The ability of spermatozoa to fertilize an oocyte depends on a sequence of events ending ultimately in the decondensation of the sperm chromatin on penetration of the oocyte. Knowledge of what percentage of sperm decondenses is useful, especially in patients where other functional tests and sperm quality fail to explain the reported poor in vitro fertilization (IVF) rates. The objective of this study was (1) to compare sperm decondensation induced by either SDS/EDTA or heparin with semen parameters (volume, concentration, motility and morphology), and (2) to evaluate the use of a simplified staining technique (Diff QuikR [DQ]) in comparison with the standard phase contrast method (Rose Bengal-[RB]). Randomly selected semen samples from 31 men attending an assisted reproductive programme were analysed for basic semen parameters and decondensation with SDS/EDTA and heparin. Two staining methods for the evaluation of decondensation were compared (phase contrast microscopy after Rose Bengal [RB] staining and light microscopy after Diff QuikR (DQ) staining). Moderate and grossly swollen sperm heads were recorded. Semen samples included both fertile and unfertile semen parameters. Sperm decondensation results showed poor to moderate correlations with semen parameters. The SDS/EDTA (DQ) (moderate forms) showed a significant negative correlation (r = -0.46) with seminal volume and a significant positive correlation (r = 0.41) with normal sperm morphology. The heparin (DQ) (moderate forms) decondensation showed a significant positive correlation with motility (r = 0.61) and sperm concentration (r = 0.43). The DQ method was preferred over the RB method due to its optical and storage advantage.(ABSTRACT TRUNCATED AT 250 WORDS)

Azure Stains↗

PubMed1985

Stability in cyclic epidemic models.

A general formulation for a family of cyclic epidemic models with density-dependent feedback mechanisms and removed classes is presented. A parameter, lambda, related to the basic reproductive rate determines the asymptotic behaviour of solutions of the model. It is shown that if lambda less than 1 the trivial solution is globally stable, and if lambda greater than 1 it is conditionally stable. The results are applied to a set of differential equations that has been used to model the life cycle of a parasite that has two hosts.

Animals↗