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67 records · Page 4Linked to original sources
PubMed1976

Histological aspects of cervical ripening.

There is a close relationship between the rate of the uterine cervix opening during parturition and the presence or absence of a completely ripened cervix. In order to learn the basic pattern of the ripening of cervix, histological and histochemical studies were performed on the human uterine cervix during pregnancy. It was noted that the collagen bundles disintegrated into fine fibers and also underwent quantitative changes during the ripening process of the cervix. During pregnancy, the number of connective tissue cells was increased, but that of mast cells was decreased. Acid mucopolysaccharides in the cervical ground substance were found to increase in late pregnancy.

Adolescent↗
PubMed1988

The ovarian prorenin-angiotensin system. Lessons from IVF.

Recent evidence suggests that prorenin and other active components of the renin-angiotensin system may be linked to ovarian physiology. Prorenin, the inactive form of the enzymatically active renin, is present in the fluid of mature human ovarian follicles in concentrations more than 10 times higher than that found in the plasma of women undergoing ovarian stimulation. Only 1% of the renin in follicular fluid is in active form. Concentrations of prorenin in fluid of immature follicles are lower than levels detected in concomitantly aspirated mature follicles. Study of prorenin levels disclosed a positive correlation to testosterone and E2 in fluids of mature follicles. Plasma prorenin increases about twofold at midcycle at the time of the LH surge; the peak of prorenin is sustained for about 40 hours. In patients undergoing ovarian stimulation for IVF, hCG administration results in much higher plasma prorenin levels and the height of prorenin response is directly related to the number of mature follicles. It peaked 4 to 6 days after hCG injection and then fell, close to baseline, by about 12 days after hCG administration. Examination of the time course of hormonal changes in response to hCG revealed a temporal relationship between prorenin and both plasma E2 and progesterone. In women who conceived, prorenin began to rise again on days 8 to 12 after embryo transfer when endogenous hCG was detected in the blood. No such changes in prorenin occurred in women with ovarian failure who conceived after transfer of a donor egg. These findings indicate that prorenin is produced by the mature follicle and the corpus luteum in response to LH/hCG. Since angiotensin II affects intracellular calcium and phospholipase activity, there are many potential roles for prorenin via angiotensin II action. Putative actions of the ovarian renin system may include control of oocyte maturation, ovulation, ovarian blood flow, and ovarian steroid biosynthesis. Future work to elucidate the function of this new renin system may have relevance to many basic and clinical aspects of human reproduction.

Enzyme Precursors↗
PubMed1978

Sperm basic proteins in cervical carcinogenesis: Correlation with socioeconomic class.

Two types of basic protein, a histone and a protamine, were separated from single ejaculates of human sperm and a ratio between their contents in a given number of sperm established. The ratio varied widely in different males and correlated with ranking by social class: the lower the social class, the greater the proportion of protamine. Statistically similar correlations link social class with the incidence of venereal disease and the incidence of in-situ carcinoma of the cervix, both of which are epidemiological variables in squamous cervical cancer. The basic proteins of the sperm head, especially the protamines, may thus also have a role in the aetiology of squamous cervical cancer.

Carcinogens↗
PubMed1992

[Reproductive health survey of young adults in greater Santiago].

In 1988 a survey was carried out in order to obtain information on knowledge about reproduction, sexual activity, attitudes, and use of contraceptive methods among residents between 15 and 24 years of age in Greater Santiago. For this purpose, a multistage, self-weighted, non-replacement probability sample was chosen from the entire Santiago urban area. After 2,898 households were visited, 865 women and 800 men were selected and interviewed. For the interview, a questionnaire with 156 questions was developed; many questions were similar to those included in similar surveys in Brazil and Guatemala. The interviewers were professionals who had received prior training. Although 75% of the interviewees had attended sex education classes, they had erroneous ideas on various basic subjects. Sixty-nine percent of the women interviewed had undergone menarche before attending these classes. In addition, 35.4% of the women and 65.0% of the men had had sexual relations prior to marriage, and less than 20% had used any contraceptive method. More than 60% of the interviewees who had children had conceived them before marrying. These findings point up the necessity of offering sex education classes for children and young people, as well as facilitating their access to family planning services, in order to decrease the number of illegitimate and unwanted children that are born in Chile.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Acute lithium treatment suppresses the proestrous LH surge in mice: chronic lithium leads to constant diestrus.

Although the therapeutic usefulness of lithium in manic-depressive psychosis is now well-established, a number of basic and clinical studies in recent years have shown that the administration of this anti-manic drug produces a wide range of adverse endocrine and metabolic effects. The present study was undertaken in order to examine (a) what effects acute lithium administration might have on the preovulatory surge of luteinizing hormone (LH) during proestrus, and (b) whether chronic lithium administration has any adverse effect on the estrous cycle in C57BL/6 mice. Acute injections of lithium on the day of proestrus (at 10.00, 16.00 and 18.00 h; LD 14:10; lights on at 05.00 h CST) at a dosage of 5 mEq/kg b. wt. led to a significant (P less than 0.01) suppression of the LH surge that normally occurs in the evening of proestrus at 21.00 h. Chronic administration of lithium, on the other hand, resulted in a complete disruption in the regularity of the estrous cycle. This was characterized by an increasing number of mice showing a continuous diestrous vaginal smear during the first week of exposure to lithium, after which all of the lithium-treated mice completely stopped cycling and entered into constant diestrus. These results represent for the first time that lithium has significant adverse effects on the reproductive function in the female, especially in regard to the proestrous LH surge and estrous cyclicity in mice. Since these adverse effects were manifested under conditions when plasma lithium concentrations were within or around the therapeutic range, our results provide important conceptual information concerning possible adverse effects of lithium on the reproductive function in the human female.

Animals↗
PubMed1987

Protective legislation, ionizing radiation and health: a new appraisal and international survey.

Restrictive regulations ("protective legislation") on employment conditions of female workers limiting maximum hours of work and prohibiting certain toxic exposures have existed for decades. In some countries, such as the United States, Canada and the Nordic countries, the growth of civil rights and equal opportunity legislation has led to their elimination, either in fact or in practice, and only a small number of disparate regulations for male and female workers still exist. Most other industrialized countries, as well as the International Labour Office of the United Nations, still have active restrictive rules for women's employment. However, restrictive regulation is an area of active policy debate around the world. International examples of the debate on protective legislation are given here. A specific case study of the occupational health standards governing exposure to ionizing radiation is used and its technical rationale discussed as an illustration of the basic issues. These include: overbroad categorization of all women as potential childbearers, no matter what their childbearing intentions; failure to recognize the full range of potential adverse health effects to males; disparate application of the restrictive regulations, generally to occupations or areas of employment that are traditionally held by men, while traditional female jobs with the same exposures are excluded from the regulatory restriction.

Adult↗
PubMed1991

The WHO Task Force on Vaccines for Fertility Regulation. Its formation, objectives and research activities.

Over the past 18 years, the WHO Task Force on Vaccines for Fertility Regulation has been supporting basic and clinical research on the development of birth control vaccines directed against the gametes or the preimplantation embryo. These studies have involved the use of advanced procedures in peptide chemistry, hybridoma technology and molecular genetics as well as the evaluation of a number of novel approaches in general vaccinology. As a result of this international, collaborative effort, a prototype anti-HCG vaccine is now undergoing clinical testing, raising the prospect that a totally new family planning method may be available before the end of the current decade.

Animals↗
PubMed1989

Cloning of Tetrahymena genomic sequences whose message abundance is increased during conjugation.

A molecular and biochemical inquiry into protein regulation during Tetrahymena thermophila conjugation was carried out in two ways: a two-dimensional gel analysis of newly translated proteins and the molecular cloning of genes whose message abundance is increased. The two-dimensional gel analysis indicated that the synthesis of 32 predominantly basic proteins was stimulated in conjugating cells. The induction of these proteins could not be correlated with length of starvation or with mating type. The transcription pattern and molecular organization of three clones of T. thermophila genomic DNA, selected on the basis of differential hybridization to conjugating or control cell RNA, were investigated. Two of the clones, which were homologous to transcripts detected in conjugating cells, showed no rearrangements between micro- and macronuclear DNA. A third clone was divided into three segments. One segment was homologous to sequences limited to the micronucleus. A second segment hybridized to a large number of restriction fragments of micronuclear DNA digested with HindIII but to only two fragments of macronuclear DNA. A third segment, which was complementary to one transcript in conjugating cells and to two different transcripts in control cells, hybridized to two fragments in micronuclear DNA and one fragment in macronuclear DNA.

Animals↗
PubMed1981

Interactions among endocrine control systems in the regulation of ovarian function.

During sequential physiologic maturation of an individual follicle, the number of granulosa cells increases in excess of 1000-fold, while intra-ovarian concentrations of sex steroids escalate by 100-fold. The recent development of several in vitro ovarian systems has permitted a more extensive and direct assessment of specific mechanisms that control growth and steroidogenesis in granulosa and thecal cells. For example, estradiol and follicle stimulating-hormone seem to promote the production by ovarian cells of low-molecular-weight growth factors, that may participate in granulosa cell proliferation. Luteinizing hormone stimulates the de novo synthesis of prostacyclin by granulosa cells in vitro. Prostacyclin, in turn, may regulate the microvasculature of the maturing follicle and directly stimulate steroidogenesis. The effects of individual hormones are markedly modified by other intraovarian endocrine factors, and by the precise status of cytodifferentiation of the ovarian cells. For example, the actions of prolactin on granulosa-cell steroidogenesis are influenced strikingly by both agonistic and antagonistic interactions between prolactin and estradiol, as well as by the level of granulosa-cell cytodifferentiation attained in vivo. Similar bihormonal intrafollicular interactions are recognizable between estrogen and follicle-stimulating hormone in the early follicle, and between estradiol and luteinizing hormone in the maturing follicle. These interactions are susceptible to more precise examination under defined in vitro conditions. Overall, recent advances in biomedical research continue to elucidate basic molecular mechanisms of hormone action in ovarian cell physiology. Such advances are likely to continue to provide important insights into the pathophysiology of clinical disorders of human reproduction.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Planarians as a model system for in vitro teratogenesis studies.

Free-living flatworms such as planarians are inexpensive to culture, maintain, and use for toxicologic testing in the laboratory. A considerable number of basic studies by ourselves and others indicate that, in simplified miniature, they possess many features of biochemical and physiologic organization similar to higher animals such as mammals. These include a well-developed brain with a varied behavioral repertoire including complex maneuvers of prey capture and learning, with a number of the same neurotransmitters used in mammalian brain. They are sensitive to a variety of the same toxicants. Undifferentiated totipotent stem cells, i.e., "neoblasts," which are capable of mitosis and differentiation into any of the various specialized cell types, permit regeneration of complete planarians from fragments. They also provide new cells to replace those lost in the normal cellular turnover of nonregenerating planarians. Both regeneration of surgical fragments and aberrant remodeling of whole planarians model important features of embyrogenesis and are potentially useful for assaying teratogens. Results are described from studies in which various representative teratogenic toxicants were tested in these two different planarian paradigms. The potential of planarian cephalic regeneration for behavioral teratogenesis investigations is also indicated.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Vitamin A and carotene in animal nutrition.

Vitamin A, an unsaturated 20 carbon cyclic alcohol, subserves a number of important physiological functions. However, the biochemical basis of these roles is not well understood. The main sources of retinol are liver, egg yolk and milk fat. Several carotenoids show vitamin A activity. The conversion of beta-carotene to retinol is affected by copper-containing dioxygenase and zinc-containing retinene reductase. The efficiency of conversion varies in different species. The latter is defined in units as the daily dose required to produce a weight gain of 3 g/week in young rats between the 4th and 8th week. Retinol is unstable on exposure to light or heat, particularly in the presence of heavy metal ions and water. Much recent work has focused on the absorption, metabolism and excretion of vitamin A. It is now recognized that plasma vitamin A levels do not reflect the nutritional status except in severe hypo- and hypervitaminosis A. Also, many dietary factors may influence vitamin A metabolism. These basic and applied aspects of vitamin A are reviewed.

Absorption↗
PubMed1979

Nutritional anemia: its understanding and control with special reference to the work of the World Health Organization.

Since 1949, the World Health Organization, recognizing the public health importance of nutritional anemia, has sponsored efforts directed towards its understanding and control. During this period, often as a result of the work of the Organization, advances have been made in many areas. Basic understanding of iron, folate and vitamin B12 nutrition, and the various factors which may influence the availability and requirements of these factors, has greatly increased. Surveys in a number of countries have highlighted the widespread prevalence of nutritional anemia, particularly in developing countries. The major factor responsible is a deficiency of iron, whith folate deficiency also playing a role in some population groups, especially in preganant women. There is increasing evidence that anemia adversely affects the health of individuals and may have profound socioeconomic consequences. Control of nutritional anemia is possible by providing the deficient nutrient(s) either as therapeutic supplements or by fortification of commonly used foodstuffs. Some control programs are reviewed and suggestions for further action outlined. The Organization still has an important role to play in this field, encouraging the development of control programs and providing advice and technical assistance ot member countries.

Adolescent↗
PubMed1984

Gonadotropin-releasing hormone: molecular and cell biology, physiology, and clinical applications.

The observations in recent years that gonadotropin-releasing hormone ( pyroGlu1 -His2-Trp3- Ser4 -Tyr5- Gly6 -Leu7-Arg8-Pro9- G ly10NH2 [GnRH]) has considerable clinical efficacy as a contraceptive, an ovulation-inducing agent, and a drug that is useful in the therapy of a number of diseases are owed in no small part to advances that have been made in the basic molecular biology and physiology of this peptide. It is reasonable then that this symposium should be broken down into three separate yet integrated areas: 1) the molecular and cellular biology of GnRH, 2) the physiology of GnRH, and 3) the clinical efficacy of this compound. A number of recent advances have helped the progress of work in all three of these areas. The observation that substitution of a D-amino acid in the sixth amino acid position leads to considerable metabolic stability and reduced degradation of releasing hormone analogs has been especially useful. In addition, the observation that the further derivatization of such substituted compounds by deletion of the 10th amino acid and addition of an ethylamide group to Pro9 has resulted in compounds with a markedly increased ability to bind to the receptor. These compounds have been useful clinically and have allowed development of radioligand assays to be used in animal studies and in vitro. The availability of a large number of agonists and antagonists has allowed formulation of molecular models for GnRH and resulted in development of clinically useful compounds. In a short paper of this nature we cannot hope to provide an encyclopedic review; rather we hope to provide an overview and offer references to the literature for those who wish a more in-depth treatment.

Aging↗