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  1. 1

    Biology of human reproduction.


    Geneva, World Health Organization, 1964. (Technical Report Series No. 280.) 30 p.

    A WHO Scientific Group on the Biology of Human Reproduction was convened in Geneva from April 2-8, 1963, for the purpose of advising the Director-General on developments and major research needs in that field. The biology of human reproduction is an extremely broad scientific topic, which impinges to some degree on virtually all the basic medical disciplines. Major topics included in the report are: 1) comparative aspects of reproduction; 2) neuroendocrine aspects of reproduction; 3) biology of the gonads and gametes; 4) gestation; 5) biochemistry of the sex steroids; 6) immunological aspects of reproduction; and 7) pharmacological aspects of reproduction. The Group recommends: 1) that WHO assist in the development of fundamental knowledge of the biology of human reproduction and of other fields on which that knowledge is based and 2) that WHO convene meetings of appropriate specialist groups to consider practical methods of implementing certain proposals concerning organization of surveys, provision of services, and promotion of relevant research.
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  2. 2

    Progress in research into new methods of fertility regulation for men.


    Research results by the UNDP/UNFPA/WHO/World Bank Special Program in Human Reproduction published in 1990 showed that hormones can be used to reduce men's sperm levels to virtual infertility. Weekly injections of testosterone enanthate (TE) produced azoospermia in most men. A multicenter study was also completed in 1994 involving a total 399 men in nine countries who were given regular injections of TE. High contraceptive effectiveness resulted among those men whose sperm concentrations were reduced to 3 million or less per ml (oligozoospermia). The failure rate was 1.4 pregnancies per 100 person-years, similar to that of oral contraceptives. It took an average of 68 days to reach oligozoospermic and 100 days to reach azoospermic sperm counts after the 1st injection. To return to normal levels after the last injection took 112 days and 203 days, respectively, in oligozoospermic and azoospermic men. Testing of testosterone buciclate (TB) was also carried out in Germany to assess the effect of longer-acting androgen esters suppressing gonadotrophin secretion. Azoospermia was achieved in some men by giving a single dose of 1200 mg of TB, but at half that dose oligozoospermia was not reached. Research is also continuing into the male contraceptive effect of progestogen-androgen combinations. Progestogen prevents the production of sperm at much lower doses than androgen. Androgen is given to replace testosterone that is inhibited as a result of the suppression of gonadotrophin, but it is needed less frequently. The combination seems to suppress sperm production more quickly than the androgen alone. In China, India, and Indonesia, plans are prepared for efficacy studies with such combinations. The drawback for large-scale use is that the components have to be injected at different intervals. This may be overcome by combining TB with a progestogen with the same duration of action and giving both at the same time.
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  3. 3

    Prospects for developing vaccines to control fertility.

    Ada GL; Basten A; Jones WR

    NATURE. 1985 Sep 26 - Oct 2; 317(6035):288-9.

    A fertility-regulating vaccine could provide an efficient, safe, and inexpensive contraceptive method. The antigens selected for such vaccines must be present transiently and in low amounts relative to the predicted antibody response, specific, chemically well characterized to facilitate manufacture, and restricted to gametes or the early products of fertilization. To be acceptable, the vaccine should have an efficacy rate of at least 90%. Over the past decade, the World Health Organization (WHO) has sponsored research on the development of a vaccine based on a polypeptide of the beta subunit of human chorionic gonadotropin (hCG). A prototype vaccine on which preclinical toxicity and safety evaluations have been completed is now ready for clinical testing. WHO plans to carry out a clinical trial to assess the immunologic efficacy and safety of the vaccine as soon as approval from regulatory agencies has been obtained. Significant progress has also been made in the search for other vaccine candidates. Sperm antigens comprise one such possibility for both males and females. Of the sperm antigens identified to date, only lactate dehydrogenase (LDH-4) has been well defined. Immunization with well characterized zona pellucida antigens can inhibit fertility in many species; however, there is an unacceptable alteration in ovarian function. Trophoblast surface antigens have the advantage of being expressed at only 1 anatomic site after fertilization and of being in intimate contact with maternal blood at a very early stage of pregnancy. The search for an appropriate iso-immunogen has been facilitated by the use of recombinant DNA technology and other techniques of molecular biology.
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  4. 4

    Contraceptive technology in the future. [Editorial]

    Corbin A

    Advances in Steroid Biochemistry and Pharmacology. 1979; 7:1-8.

    Due to the numerous adverse side effects of steroidal contraceptives which continuously arise and result in potential decreases in the benefit-to-risk ratio, new chemical and biologic strategies need to be designed and implemented to assure continued success in the contraceptive area. Novel contraceptive stragegies include both new chemical classes and their receptive biologic targets. 4 basic pharmacologic approaches subserve female contraception: inhibition of ovulation; inhibition of fertilization; inhibition of implantation; and interruption of established implantation. Many diverse compounds have been evaluated in regard to a male contraceptive, but problems of toxicity and loss of libido have made the search difficult. The problem is further complicated by the task of trying to eliminate the hundreds of millions of sperm that are constantly being produced and which are in different stages of the spermatogenic cycle. This task calls for chronic dosing and the accompanying problem of eventual liver involvement and hypertrophy of the secondary accessory sex organs. An interesting area supported by the World Health Organization is the identification of plants and the isolation of their active principles for fertility regulating purposes. The United States National Institute of Health supports 3 major and separate programs related to contraception: 1) synthesis and testing of anti-ovulatory agents; 2) synthesis and testing of male contraceptive agents; and 3) peptide antagonists of LH-RH (luteinizing hormone-releasing hormone) as ovulation inhibitors. The following categories represent areas of research that might prove fruitful: LH-RH agonists; LH-RH antagonists; non-natural synthetic products; inhibin; and plant extracts. These categories are reviewed.
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  5. 5

    Summary of findings and recommendations (on reproductive physiology and the regulation of fertility.)

    Greep RO; Koblinsky MA; Jaffe FS

    In: Greep, R.O., Koblinsky, M.A., and Jaffe, F.S. Reproduction and human welfare: a challenge to research. Cambridge, Massachusetts, MIT Press, 1976. p. 1-36

    The findings and recommendations summarized are those of more than 160 experts from 26 nations who collaborated in an intensive review of the reproductive sciences and contraceptive development sponsored by the Ford Foundation and the International Development Research Center of Canada. The experts aimed at evaluating progress and identifying gaps in knowledge, at identifying sources and tracking levels of support for the field, and at outlining the scope of a program of research and development adequate to worldwide needs. The social context of the field and its substantive development, especially since 1960 are addressed. The professional and institutional resources at work and trends in financial support by country, sector, and purpose are described. 20 recommendations of the group are outlined. 3 are described as overriding: a wider variety of safe, effective contraceptive methods must be developed, more attention must be given the question of long-term safety of current and yet to be developed methods, and by 1980 a lot more money must be allocated to research and development than now is. The remaining recommendations fall under the general categories of emphasis within the field, geographical distribution of responsibility, the strengthening of institutional and professional capacity, and monitoring progress in the field.
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