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PubMed2004

Intraovarian cavity leucocytes of viviparous fish, Neoditrema ransonneti (Perciformes, Embiotocidae).

To obtain basic information on the properties of the intraovarian cavity leucocytes (IOCLs) of the viviparous teleost, Neoditrema ransonneti, morphological characteristics and numerical changes of IOCLs during the reproductive cycle were investigated. In the ovaries of newborn females, leucocytes exuded into the lumen were observed first in November, prior to insemination of semen. These cells were primarily macrophages, neutrophils and lymphocytes. Among them, macrophages were invariably the largest population throughout the reproductive cycle. They began to phagocytize spermatozoa in December, when spermatozoa were first detected in the ovary. The number of IOCLs gradually increased from November in the newborn female. However, this increase is not ascribed to the effect of copulation or the presence of semen, because the number of leucocytes also increased in non-mating fish. While developing embryos were discharged into the ovarian lumen at the latest in January, a number of spermatozoa and spermatozoa-phagocytizing macrophages were seen until March. Even after the extinction of sperm cells, numerous IOCLs remained in the lumen and coexisted with fetuses until their parturition. These results suggest that IOCLs play roles in successful pregnancy, besides elimination of remaining spermatozoa.

Analysis of Variance↗

PubMed2001

Aspects of basic reproductive biology and endocrinology in the fathead minnow (Pimephales promelas).

The fathead minnow (Pimephales promelas) has been proposed as a model species for assessing the adverse effects of endocrine-disrupting chemicals (EDCs) on reproduction and development. The purpose of these studies was to develop baseline reproductive biology and endocrinology data for this species to support interpretation of tests with potential EDCs. Pairs of reproductively-active fathead minnows (n=70) were evaluated with respect to reproductive cyclicity in terms of spawning interval and fecundity. The mode and mean (+/-SE) spawning intervals for the fish in this study were 3.0 and 3.7+/-0.1 days, respectively. The mean number of eggs produced per spawn was 85+/-2.8. Animals were sacrificed at periodic intervals during the established spawning cycle and measurements made of gonadal condition (gonadosomatic index [GSI], histopathology) and plasma concentrations of vitellogenin and sex steroids (beta-estradiol, testosterone, 11-ketotestosterone). The GSI in females varied significantly as a function of spawning interval, with the largest values occurring day 2 post-spawn, just prior to the interval of maximum spawning activity. Plasma beta-estradiol concentrations in females also varied significantly relative to peak values in the GSI and spawning activity. Vitellogenin concentrations in the female, and male GSI and steroid concentrations did not vary significantly relative to position in the spawning cycle. Concentrations of beta-estradiol in females and 11-ketotestosterone in males were positively correlated with testosterone concentrations.

Animals↗

PubMed1982

Patterns of periovulatory oviductal motility and progesterone in the unanesthetized rabbit.

Pairs of miniature extraluminal force transducers were chronically implanted on the isthmus of 26 rabbits without disturbing reproductive function. No alterations were noted in the transducer-bearing animals in the numbers of corpora lutea, uterine implants, or viable conceptuses, or in fertility, pregnancy rates, rates of ovum transport, or peripheral plasma levels of progesterone (P) or estradiol (E2). Using these devices, isthmic motility was recorded in 14 unanesthetized rabbits throughout the 72 h following human chorionic gonadotropin injection (hCG) (75 IU) and coitus. This activity was comprised of distinct bursts (B) of intense contractile activity, interspersed with periods (IB) of relative quiescence. Although the basic pattern of B and IB periods persisted throughout this interval, significant changes were noted in the duration of its components. During this period, B durations increased, with all values greater (P less than 0.01) than estrus from 24 h following the ovulatory stimuli. IB durations diminished somewhat at 24 h, but were markedly prolonged at 60 and 72 h. The proportion of time spent in bursting activity was maximal and significantly greater than estrus (P less than 0.01) at 24 h, a time at which ova were retained at the ampullary-isthmic junction. This proportion was minimal, on the other hand, at 60 and 72 h, when ova were moving rapidly through the isthmus and uterotubal junction. Plasma P surged from estrus to a peak at 6 h, fell until 24 h, and gradually increased through 72 h. All post-stimulus P values were greater (P less than 0.01) than at estrus. The B and IB durations at 72 h were both positively correlated with the P levels at 6 h. These findings suggest the importance of specific patterns of isthmic motility in ovum transport and of P in its regulation.

Animals↗

PubMed1988

A general model for the African trypanosomiases.

A general mathematical model of a vector-borne disease involving two vertebrate host species and one insect vector species is described. The model is easily extended to other situations involving more than two hosts and one vector species. The model, which was developed from the single-host model for malaria described by Aron & May (1982), is applied to the African trypanosomiases and allows for incubation and immune periods in the two host species and for variable efficiency of transmission of different trypanosome species from the vertebrates to the vectors and vice versa. Equations are derived for equilibrium disease prevalence in each of the species involved. Model predictions are examined by 3-dimensional phase-plane analysis, which is presented as a simple extension of the 2-dimensional phase-plane analysis of the malaria model. Parameter values appropriate for the African trypanosomiases are derived from the literature, and a typical West African village situation is considered, with 300 humans, 50 domestic animals and an average population of 5000 tsetse flies. The model predicts equilibrium prevalences of Trypanosoma vivax, T. congolense and T. brucei of 47.0, 45.8 and 28.7% respectively in the animal hosts, 24.2, 3.4 and 0.15% in the tsetse vectors, and a 7.0% infection of humans with human-infective T. brucei. The contribution to the basic rate of reproduction of the human-infective T. brucei is only 0.11 from the human hosts and 2.54 from the animal hosts, indicating that in the situation modelled human sleeping sickness cannot be maintained in the human hosts alone. The animal reservoir is therefore crucial in determining not only the continued occurrence of the disease in humans, but its prevalence in these hosts as well. The effect of changing average fly density on equilibrium disease prevalences is examined, together with the effect of seasonal changes in fly numbers on disease incidence. In a seasonal situation changes in fly mortality rates affect both future population size and infection rate. Peak disease incidence lags behind peak fly numbers, and that in the less favoured host lags behind that in the more favoured host. Near the threshold fly density for disease transmission disease incidence is more changeable than at higher fly densities and may even exceed equilibrium prevalence at the same average fly density (because most hosts are susceptible at the time that fly numbers begin their annual increase).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2002

Fecundity and life-history strategies in marine invertebrates.

The reproductive strategies of an organism play a major role in the dynamics of the population and the biogeography and continuity of the species. Numerous processes are involved in reproduction leading to the production of offspring. Although diverse processes are involved in oogenesis (the production of eggs) and spermatogenesis (the production of sperm), the basic patterns of gametogenesis are similar amongst invertebrates, with the proliferation and differentiation of germ cells leading to the final production of mature gametes. The production of gametes, especially eggs, is energetically expensive, and therefore strongly sensitive to selective pressures. An organism can ingest and assimilate a limited amount of energy from the environment. The different ways by which energy is allocated to growth and reproduction in order to maximize fitness forms the basis of the differing life-history strategies that have developed in marine invertebrates. Fecundity is defined as the number of offspring produced by a female in a determined time period. The term fecundity needs to be explicitly defined in each study in order to obtain the maximum information from the data analysed. Because of the variety of egg production patterns found among marine invertebrates, a wide range of methodologies has been developed to quantify fecundity. These include direct egg counts in brooding species, spawning induction in live individuals and histological studies of preserved material. Specific considerations need to be taken into account for colonial organisms, because of their modular organization. The production of eggs requires an optimal allocation of energy into growth and reproduction for the maximization of parental fitness. Fecundity is central in studies of life-history theory and in the development of life-history models because it is directly related to energy allocation and partitioning. There are important relationships and trade-offs between fecundity and other life-history traits, such as egg size, female size and age, age at first reproduction, reproductive effort and residual reproductive value. These trade-offs, together with morpho-functional constraints and genetic variation determine the evolution of life histories through natural selection. Fecundity is a highly plastic character within the limits defined by the bioenergetics and life-history strategy of the organism. Egg production is affected mainly by environmental factors such as food quantity and quality, temperature or presence of toxic elements in the habitat. The differences in fecundity found among closely related species from different biogeographical locations reflect, at least in part, the differing environmental conditions of their habitat.

Adaptation, Physiological↗

PubMedDate not supplied

Andrology--development and future. Critical remarks after 45 years of medical practice.

The development of andrology from its beginning to the present time is discussed from a historical point of view. Since andrology is a clinical discipline, only well-trained physicians are allowed to investigate and treat patients. The term 'andrology', which was first introduced in the USA more than 100 years ago, was independently reborn in Germany and thereafter used in other European countries. Since then, an increasing number of physicians all over the world have applied the term 'andrology' for their professional work. Many local societies and groups of andrologists were established. In 1969, Andrologia was founded as the first international journal of andrology in Germany. In the meantime, further andrological journals have been established. Concerning the future development of andrology, the following should be considered: (i) the organizational structure of andrology must include the basic training of physicians working in this field; (ii) the necessity of andrology as a medical specialty with regard to modern technologies of assisted reproduction etc., must be emphasized; (iii) internationally accepted recommendations for the training of andrologists with special reference to both clinical andrology and laboratory techniques should be established; (iv) andrology should be established as a separate specialty.

Education, Medical, Graduate↗

PubMed2001

Biotechnology and ethics in medical education of the new millennium: physician roles and responsibilities.

Although the medical education curriculum varies internationally, we suggest that it is desirable for medical educators to share a universal responsibility to prepare physicians to perform three distinct, yet interrelated professional roles. The first is that of a clinician who has the knowledge and technical skills to care for individual patients, as well as the public. The second role can be viewed as that of an educator, a teacher, or a consultant who has the interpersonal skills and personal qualities to teach, advise and counsel patients and the public about their health and illness, risk factors and healthy lifestyle. The third role is that of a resource manager to enable physicians to care for patients and serve the public not only by drawing on available material assets but also by prudent use of the resources for better serving the most number of people at the least expense without compromising the quality of care. The very nature of the medical profession also obligates medical educators through the world to sensitize medical students and physicians to the ethical responsibilities that are implicit to each of the three aforementioned roles. Although the basic ethical responsibilities of do no harm and confidentiality are universal, certain global changes, such as rapid advancements in biotechnology and resource allocation, are now reshaping medical ethics on every continent. Spawned by the rapid advances in the biomedical sciences, biotechnology is revolutionizing human reproduction, sustaining human life, cloning human beings, and mapping the entire human genetic terrain. These advances imply changes in medical education and formal preparation of physicians in performing their roles as clinicians, educators and resource managers. These biotechnological developments, coupled with the increasing cost of healthcare and maldistribution of resources worldwide, present unprecedented ethical-social challenges that need to be addressed in the education of the physician in the new millennium.

Journal Article↗

PubMed2001

Genetics, biotechnology and population management of over-abundant mammalian wildlife in Australasia.

Wildlife management involves regulation of population numbers of wild vertebrate species. In some cases there are too many animals and in others there are too few. Genetic issues arise in both instances. The historical and genetic evidence for the number of mammals that were in the founder populations of successful colonizing species in Australia and New Zealand is reviewed here. Small numbers have often given rise to large populations, despite the concomitant loss of genetic variability. Restriction of the number of over-abundant and pest species by either physical or chemical methods frequently constitutes very strong artificial selection, which leads to rapid genetic change; an example of major importance in the two countries is sodium monofluoroacetate (compound 1080). Pathogenic agents, surgical sterilization, hormonal contraceptives and translocation have all been used with varying degrees of success. The strengths and weaknesses of these techniques are assessed. A method that has received much attention is immunocontraception. We argue that this attempt to use the animals' own immune system to modulate reproduction is incompatible with the basic biological function of protection against infectious disease. Immune function genes are highly variable in vertebrates, and so often genetic change in the population subjected to immunocontraception is likely to be even more rapid than is the case with lethal agents. Selection for failure to respond to the immunocontraceptive will occur, and will change immune function in general. Poor scientific description of ecosystem complexity makes it difficult to predict the consequences of immunocontraception on wildlife populations.

Animals↗

PubMedDate not supplied

Perinatal mortality and morbidity in rural West-Java, Indonesia. Part I: Vital statistics based on cross-sectional surveys.

The first part of this article gives the summary result of 4 cross-sectional surveys conducted in 3 rural villages in West Java. It is expected that these surveys provide the researchers with more precise data on perinatal mortality and its associated causes in order to plan and implement the Tanjungsari Intervention Study (1986-1990). This comprises a mapping and numbering survey, and a census survey. Based on a sampling frame of 7964 houses, a systematic sample (one in eleven) was drawn for the Household and for the Married Women Surveys. The survey results yield some basic demographic indicators, occupational information and data on education. Also data on environmental health and vital statistics are presented. It is shown that the crude birth rate is 40 per thousand and that the estimated infant mortality rate reaches a figure of 120%. Furthermore, during individual interviews data was collected on characteristics, attitudes habits as well as on reproductive behaviour, of all married women under 50 years of age.

Adolescent↗

PubMed2006

Deafness, genetics and dysgenics.

It has been argued by some authors that our reaction to deaf parents who choose deafness for their children ought to be compassion, not condemnation. Although I agree with the reasoning proposed I suggest that this practice could be regarded as unethical. In this article, I shall use the term "dysgenic" as a culturally imposed genetic selection not to achieve any improvement of the human person but to select genetic traits that are commonly accepted as a disabling condition by the majority of the social matrix; in short as a handicap. As in eugenics, dysgenics can be achieved in a positive and a negative way. Positive dysgenics intends to increase the overall number of people with a particular genetic trait. Marriage between deaf people or conceiving deaf children through reproductive technology are examples of positive dysgenics. Negative dysgenics can be obtained through careful prenatal or pre-implantation selection and abortion (or discarding) of normal embryos and foetuses. Only deaf children would be allowed to live. If dysgenics is seen as a programmed genetic intervention that undesirably shapes the human condition--like deliberately creating deaf or dwarf people--the professionals involved in reproductive technologies should answer the question if this should be an accepted ethical practice because the basic human right to an open future is violated.

Deafness↗

PubMed2004

A possible route to prebiotic vesicle reproduction.

Spherical bounded structures such as those formed by surfactant aggregates (mostly micelles and vesicles), with an inside that is chemically and physically different from the outside medium, can be seen as primitive cell models. As such, they are fundamental structures for the theory of autopoiesis as originally formulated by Varela and Maturana. In particular, since self-reproduction is a very important feature of minimal cellular life, the study of self-reproduction of micelles and vesicles represents a quite challenging bio-mimetic approach. Our laboratory has put much effort in recent years into implementing self-reproduction of vesicles as models for self-reproduction of cellular bounded structures, and this article is a further contribution in this direction. In particular, we deal with the so-called matrix effect of vesicles, related to the fact that when fresh surfactant is added to an aqueous solution containing preformed vesicles of a very narrow size distribution, the newly formed vesicles (instead of being polydisperse, as is usually the case) have dimensions very close to those of the preformed ones. In practice, this corresponds to a mechanism of reproduction of vesicles of the same size. In this article, the matrix effect is re-elaborated in the perspective of the origin of life, and in particular in terms of the prebiotic mechanisms that might permit the growth and reproduction of vesicles. The data are analyzed by dynamic light scattering with a new program that permits the calculation of the number-weighted size distribution. It is shown that, on adding a stoichiometric amount of oleate micelles to preformed oleate vesicles extruded at 50 and 100 nm, the final distribution contains about twice the initial number of particles, centered around 50 and 100 nm. The same holds when oleate is added to preformed phospholipid liposomes. By contrast, when the same amount of oleate is added to an aqueous solution (as a control experiment), a very broad distribution ranging between 20 and 1000 nm is obtained. The data can then be seen as a kind of reproduction of the same size vesicles, and the argument is advanced that this may correspond to a simple prebiotic mechanism of vesicle multiplication in prebiotic times, when only physical forces might be responsible for the basic mechanisms of early protocell growth and division. Preliminary data also show that repeated addition of oleate maintains the same basic initial features, and that surfactants other than oleate also respect the reproductive mode of the matrix effect.

Cell Physiological Phenomena↗

PubMed2000

Human adaptability research into the beginning of the third millennium.

Human adaptability, as a field of inquiry within human biology, became defined during the research activities of the International Biological Program (IBP) (1964-1974). During this period, research was focused on ecological, physiological, and genetic studies of human populations within the theoretical frameworks of adaptation and evolution. Other defining characteristics of the IBP human adaptability research were standardization of methods, multidisciplinary projects, international cooperation, and a concern with human health issues. Some observers suggest that this research contributed to the ongoing transformation of physical anthropology and related fields from a largely descriptive to an analytical science. During the 25 years between the end of the IBP and the present, a number of research trends have continued: Several new multidisciplinary projects were initiated and completed; a subfield of demography within human biology has matured; nutrition, infant and child growth, and health studies have proliferated; and molecular genetics and DNA analysis have superseded the earlier population genetics. International programs today are geared toward more practical and applied studies with less emphasis on basic science. Continuation of human adaptability research into the 21st century is likely to make contributions in 3 broad areas: population, environment, and health. Productive research is likely to contribute to these 3 areas in the following categories: reproduction, psychosocial stress, life span approaches to health, effects of losses in biodiversity on health, a human biology of poverty, emerging infectious diseases, epidemiology of modernization, evolutionary medicine, and aging. The success of much of this research in its contribution to knowledge will come from the integrated perspectives of a biobehavioral framework of inquiry.

Adaptation, Physiological↗

PubMed2002

Flow cytometry in human reproductive biology.

Flow cytometry (FC) is an analytical cytology technique which has been extensively used for decades. It has many advantages compared with other similar methods for the study of cell biology, even on a molecular basis. FC allows the cell-by-cell analysis of many optical or immunological features in the same sample, at the same time, and at a rate of thousands of cells per second, generating immense quantities of data and thus providing almost limitless information which is statistically robust due to the number of units studied. The aim of this review is to describe the contribution of FC to the study of physiological and pathological processes related to human reproduction, and to discuss how this technique has been used in research, as well as its clinical applications in this field. We have used some practical examples selected from the most relevant studies within a wide range of investigations published in the literature, and we have also drawn on our own experience of using flow cytometry to study different phenomena related to reproduction. It is conclued that FC is a useful instrument for basic investigation of gynecological issues, as well as for the study of male reproductive characteristics, either in research applications or directly for clinical diagnostic purposes. Future development of these techniques will permit further advances both in our knowledge and in the improvement of assisted reproduction techniques.

Acrosome Reaction↗

PubMed2001

In vitro development of pig preantral follicles.

A limiting factor to realizing the full potential of many of the new reproductive techniques is the lack of abundant numbers of fertilizable oocytes. This problem could be addressed by using the large source of oocytes available from preantral and primordial follicles by developing systems for in vitro growth. In vitro systems that use early growing follicles as a source of oocytes have been developed for laboratory species and these have been successful in producing live young. If successful, in vitro growth in association with in vitro maturation (IVM) and cryopreservation would optimize in vitro production systems. In vitro growth systems that support the growth of pig preantral follicles have been developed and have been successful in producing meiotically competent oocytes but, to date, no live young have been produced. However, these systems remain to be characterized and their main application is as experimental models to study the processes of early oocyte and follicle development. This review provides an overview of culture systems that have been developed for domestic species and discusses how these are furthering our basic knowledge of early follicular development, as well as considering the benefits and potential problems associated with in vitro growth systems.

Animals↗

PubMed2002

Cell-cell interactions in primordial follicle assembly and development.

Two critical processes in ovarian biology are the assembly of the primordial follicles early in development and then the subsequent development and transition of the primordial follicle to the primary follicle. These processes directly effect the number of oocytes available to a female throughout her reproductive life. Once the pool of primordial follicles is depleted a series of physiological changes known as menopause begins in humans. The inappropriate coordination of these processes contributes to ovarian pathologies such as premature ovarian failure. Studies demonstrate primordial follicle assembly and development are coordinated by locally produced paracrine and autocrine factors. Factors have been identified that influence follicular assembly such as neurotropins. Several local factors that promote the primordial to primary follicle transition have also recently been identified. These include growth factors such as kit-ligand, leukemia inhibitory factor and basic fibroblast growth factor. Interestingly, recent studies demonstrate Müllerian inhibitory substance appears to inhibit the primordial to primary follicle transition. Therefore, observations suggest a mechanism for both positive and negative control of the primordial to primary follicle transition. The studies reviewed regarding the control of primordial follicle assembly and the primordial to primary follicle transition help elucidate these poorly understood aspects of ovarian biology.

Animals↗

PubMed2004

The use of hormonal treatments to improve the reproductive performance of lactating dairy cows in feedlot or pasture-based management systems.

Hormonal interventions have been used to increase the probability of estrous detection and insemination, and to increase pregnancy rates of dairy cattle under a variety of management systems. The present review addresses the basic principles of hormonal intervention and presents typical examples that illustrate the methodology. The hormones used to control the estrous cycle mimic the reproductive hormones found within the normal cow. Most estrous synchronization systems employ a method for controlling follicular wave development, promoting ovulation in anestrous cows, regressing the corpus luteum in cyclic cows, and synchronizing estrus and (or) ovulation at the end of treatment. A wide range of reproductive systems are in place on dairy farms. In most herds, a non-intervention period is practiced where postpartum cows are observed estrus estrus. Cows not observed in estrus are then treated. A number of studies in pasture-based and confinement systems have demonstrated net benefits of whole-herd synchronization. Despite the advantages of whole-herd reproductive programs, their uptake has been inconsistent globally. The benefits of a timed artificial insemination (AI) system increase under conditions of poor estrous detection rate and poor conception rate. The unpopular nature of timed AI programs in pasture-fed cows relates to high rates of estrous detection and conception for pasture-based dairying. Regardless of production system, some cows must be re-inseminated because they are not pregnant after first insemination. The presence of "phantom cows" (non-pregnant cows that do not return to estrus) creates a serious reproductive challenge for both pasture-based and confinement-style operations. Early pregnancy diagnosis and second insemination timed AI may reduce the effects of phantom cows on dairy herds. Fundamental research into anestrous, the hormonal control of the estrous cycle, and early pregnancy detection should elucidate new methods that can be used to strengthen reproductive programs on dairy farms.

Animal Feed↗

PubMed2000

Atlas and histologic classification of tumors of the rat mammary gland.

Studies performed in experimental animal models have demonstrated that mammary cancer is a complex multistep process that can be induced either by chemicals, radiation, viruses, or genetic factors. Rodent models have been useful for dissecting the initiation, promotion, and progression steps of mammary carcinogenesis. Chemically induced mammary tumors, such as those induced by 7,12-dimethylbenz(a)anthracene and N-methyl-N-nitrosourea, are, in general, hormone-dependent adenocarcinomas whose incidence, number of tumors per animal, tumor latency, and tumor type are influenced by the age, reproductive history, and endocrinologic milieu of the host at the time of carcinogen exposure as well as by diet and the dose of carcinogen administered. There is a need to classify tumors according to their histopathological type because those characteristics have implications in the interpretation of experimental data. In the classification presented here we attempt to provide a working framework for diagnosis of the type of lesions found in the mammary glands of rats treated with chemical carcinogens or radiation and to clarify criteria for establishing the basic biological characteristics of tumors.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2000

Cloning and identification of regulatory gene UL76 of human cytomegalovirus.

The major immediate-early promoter/enhancer (MIEP, -1139 to +52) of human cytomegalovirus (HCMV) is regulated by cell type-specific transcriptional factors, its own MIE proteins (IE2p40, IE1p55, IE1p72 and IE2p86) as well as viral proteins pUL69, pUL82 and pUL84. To investigate the hypothesis that the regulation of HCMV MIEP is modulated by additional viral genes, HCMV (AD169) genomic sublibraries were constructed and in vitro transient co-transfection assays were performed to assess the ability of these sublibraries to modulate MIEP expression. In this study, enhancement of MIEP expression was exhibited by a number of sublibraries, from one of which a genomic clone was selected for augmentation of expression. Subcloning the insert fragment led to the identification of the responsible locus, UL76. To generate a UL76-specific antibody for immunodetection, the UL76 ORF was constructed as a histidine-tagged fusion protein that was produced in prokaryotic cells. A polyclonal antibody raised against the UL76 fusion protein immunoreacts with a protein of 38 kDa (pUL76) in UL76 ORF-transfected cells. Additionally, pUL76 is present in HCMV-infected cells at the immediate-early to late stages of the reproductive cycle. Characterized by its highly basic composition (predicted pI 11.6), a free form of pUL76 tagged with green fluorescent protein was found to localize exclusively to the nucleus. In this report, pUL76 is defined as a novel regulatory protein that modulates both activation and repression of gene expression, depending on the promoter context and the ratio of transfected effector DNA.

Base Sequence↗