WHO Scientific activities

Scientfic activities /WHO-OMS A ctivite*s scientiques Bulletin ofthe WorldHealth Organization, 63 (1): 43 - 46 (1985) i World Health Organization 1985 International Reference Strains of Laishmania The sixth meeting of the Scientific Working Group of the leishmaniases component of the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases was held in Montpellier, France, from 9 to 11 July 1984, following the Second International Symposium on Taxonomy and Phylogeny of Leishmania. The objectives of the meeting were to establish a list of International Reference Strains and to coordinate the activities of various centres involved in the identification of Leishmania. The International Reference Strains, which will be used as standards for the identification and characterization of Leishmania, were selected on the basis of the following criteria: 1. There should be at least one strain for each taxon, consistent with the designation of the taxon, that represents the typical clinical presentation in a given geographical area in which a most probable vector has been recognized. 2. Each reference strain should have been studied extensively, included in many publications, and characterized by at least two established techniques used for identification of Leishmania. 3. Each reference strain should have (as far as possible) some discriminating parameters rep- resentative of the taxon, e.g., morphological, biochemical and immunological characteristics, virulence for defined hosts, etc. After careful consideration of available information on currently available materials, the International Reference Strains of Leishmania were selected (see Table 1). In addition, the Group made the following recommendations. 1. All International Reference Strain Laboratories should use the coding system recommended by a WHO Expert Committee on Leishmaniases.a 2. The International Reference Strains should be distributed to all Reference Strain Laboratories. In addition, they should be deposited at the American Type Culture Collection, Rockville, MD, USA, for wider distribution to interested scientists. 3. The terms "strain", "stock" and "isolate" should be used as defined for Trypanosoma.b 4. Whenever possible, isoenzyme, monoclonal anti- body, and DNA analysis should be carried out on the same strains for comparison purposes. 5. A form entitled "International request form for the identification of Leishmania" was designed during the meeting (Table 2) and is recommended for use by all Reference Strain Laboratories. The com- pleted form should accompany all materials that are sent for identification. International Reference Strain Laboratories are encouraged to use automatic data processing to manage their cryobank and to develop standard software, thus permitting electronic exchange of information. 6. An effort should be made to reach a consensus on analytical procedures (i.e., identity matrices, dendrograms) for calculation of genetic distances and development of numerical taxonomy. Use of stan- dardized software should receive special attention. 7. Descriptive historical data (clinical and bio- logical information) should be provided each time Leishmania strains are exchanged. The Group also made recommendations on methods for shipment of specimens, preparation of detailed protocols of methods used for identification, reporting formats of Reference Strain Laboratories, soliciting for new Reference Laboratories, and funding.c ' WHO Technical Report Series, No. 701, 1984 (The leishmaniases: report of a WHO Expert Committee). b Bulletin of the World Health Organization, 56: 467-480 (1978). c The full report of the meeting is available, on request, from UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, WHO, 1211 Geneva 27, Switzerland. -43- 44 WHO SCIENTIFIC ACTIVITIES Table 1. Leishmania strains considered as International Reference Strains by the Scientific Working Group Analysis by: Monoclonal Species Strain designation kDNA lsoenzyme antibodies Comments L. donovani donovani MHOM/IN/80/DD8b + + - Infective in hamsters L. d. infantum MHOM/TN/80/LEM235 b + - Infective in hamsters L. donovani s.sp. MHOM/ET/67/L82 + + + Infective in hamsters L.d. chagasi0 MHOM/BR/74/M2682b + + + Infective in hamsters L. major MHOM/SU/73/5-ASKHb + + - Infective in hamsters L. major MHOM/IL/67/Jericho II + + + Infective in hamsters L. major MRHO/SU/59/P + + + Infective in hamsters L. tropica MHOM/SU/74/K27b - + L. tropica MHOM/SU/60/LRC-L39 + + + L. aethiopica MHOM/ET/72/L100b + + + L. mexicana mexicana MHOM/BZ/82/BEL2 1 b + + + Infective in hamsters L.m. mexicana MNYC/BZ/62/M379 + + + Infective in hamsters L.m. amazonensis MHOM/BR/73/M2269 b + + + Infective in hamsters L.m. amazonensis IFLA/BR/67/PH8 + + + Infective in hamsters L.m. pifanoi0 MHOM/VE/57/LL1 b + + L.m. garnhamia MHOM/VE/76/JAP78b + + + L.m. venezuelensis MHOM/VE/00/H 17 b - + + Infective in hamsters L. braziliensis braziliensis MHOM/BR/00/LTBOO1 4(L) b + + + Infective in hamsters L.b. braziliensis MHOM/BR/75/M2903 + + + Infective in hamsters L.b. panamensis MHOM/PA/71ILS94b + + L.b. guyanensis MHOM/BR/75/M4147b + + + Infective in hamsters L. enriettii MCAV/BR/45/L88 + + + Infective in hamsters and guinea pigs L. hertigi hertigi MCOE/PA/65/C8 + + + L.h. deanei MCOE/BR/74/M2674 - + - Infective in hamsters L. aristidesi MORY/PA/69/GML3 + + + L. gerbilli MRHO/CN/60/GERBILLI + + a Controversy exists as to whether these represent distinct taxa. b These strains are designated as International Reference Strains; the other strains listed have been extensively studied and characterized, but do not meet all criteria. The ovulation method of natural family planning Among the currently available methods for the regulation of fertility are those based on periodic abstinence from sexual intercourse during the fertile period of the menstrual cycle; these methods are commonly called natural family planning (NFP). One of these, the Billings ovulation method, depends on the individual woman's ability to determine her own fertile period by observing the changes that occur in sensation and appearance of the normal mucus secretion at the opening of the vagina. Because very few cross-cultural data are available on the ability of women to detect these changes, or on the effectiveness of the ovulation method in the prevention of unplanned pregnancy, the World Health Organ- ization undertook a five-country pilot study to answer these questions. The five centres were in Auckland (New Zealand), Bangalore (India), Dublin (Ireland), Manila (Philippines) and San Miguel (El Salvador). The full results of this study have now been pub- lishedd and the main findings are summarized here. d Fertility and sterility, 36: 152-158, 591-598 (1981); 40: 773-778 (1983); and 41: 593-598 (1984). For more information and/or copies of these papers, contact the Director, Special Programme of Research, Development, and Research Training in Human Reproduction, World Health Organization, 1211 Geneva 27, Switzerland. WHO SCIENTIFIC ACTIVITIES 45 Table 2. International request form for identification of Leishmania Please complete as far as possible. Date:. 1. Send results to: Name:N Address:. ................................................................................................................... 2. Person who made isolation: Name: Address:. 3. Isolate/stock code number: ....... .................... 4. Other code numbers:. 5. Country and place infection was acquired: ..................................................................................................................... 6. Year infection was acquired: ....................................................................................................................................... 7. Type of disease in man or animal: visceral ........................... diff usecutaneous ................................................ other. cutaneous ........................... leishmaniasis recidivans. mucosal.post-kala azar dermal leishmaniasis............................. 8. Number of skin lesions: single ....................... multiple . 9. Site of isolation (organ): ............................................................................................................................................. 10. How was organism isolated: (a) Culture: which medium? ......... .. ............. Did organism grow easily? Yes No (b ) Animal inoculation: species, strain .......................................................................................................................... Course of infection ............................................................................................................................................... 1. Human stock: Name of patient: ................................................................................................................................... age: .................................... sex:.ethnic origin: . 12. Animal stock: (a ) Species and/or common name: ............................................................................................................................... (b) Is there human leishmaniasis in area: Yes . .................................... No . (c) If yes: visceral . ....................................mucosal cutaneous .............. ...................... diffuse cutaneous. 12. Sandfly stock: (a ) Species: ............................................................................................................................................................. (b) Site of infection:foregut ................... midgut.hindgut . other ........................................................................................................................................... 14. Additional comments: .................................................................................................................................................................................... .................................................................................................................................................................................... .................................................................................................................................................................................... A total of 869 regularly menstruating women of pregnancies and had had no prior experience with the proven fertility were recruited to an initial study ovulation method. In the first cycle following designed to evaluate the individual's ability to detect instruction by a trained teacher, a mean of 93% were the fertile period. The overall mean age of the women able to identify the cervical mucus symptoms of the was 30 years; they had a wide range of socioeconomic fertile period. A history of pathological vaginal and educational backgrounds, with 13% of subjects discharge did not affect the subjects' ability to being illiterate, and 8% having had a university recognize the mucus pattern. The rules of the ovu- education. They had had an average of 3.9 lation method required 17 days of abstinence out of WHO SCIENTIFIC ACTIVITIES a mean cycle length of 29 days during the learning phase. Five per cent of the subjects had an unplanned pregnancy during this learning phase. Of the 765 who successfully learned the method, 725 (880o) entered a 13-cycle (approximately one year) study of the effectiveness of the ovulation method. The overall pregnancy rate was 22.5 per 100 woman-years (13.8 in Manila, 19.6 in Bangalore, 19.7 in Dublin, 32.8 in San Miguel, and 33.6 in Auckland). It is noteworthy that the most common reason for pregnancy was a conscious departure from the rules of the method (which requires abstinence during the fertile phase); this accounted for 15.4 of the 22.5 pregnancy rate. The mean pregnancy rate when all the rules of the method were observed (i.e., the method failure rate) was 2.8 per 100 woman-years (0 in Bangalore, 0 in San Miguel, 1.1 in Manila, 5.1 in Dublin, and 9.4 in Auckland). The reasons for the high method failure rates in the two developed countries are unclear. The mean probability of discontinuation from the study was 35.6%, ranging from 25.8% in Bangalore to 48.2% in Auckland. The mean pregnancy rate was lower in those who wished to limit their family size (17.1 No) than in those who were using the method for spacing (22.2%). The mean discontinuation rate was also lower in the "limiters" (29.1 07) than in the "spacers" (43%o). The rates of spontaneous abortion and of congenital malformation did not differ from corresponding rates in the community or from those associated with other fertility regulating methods, although the study was not of sufficient size to address these issues with any certainty. There were indications that the successful use of the method depended on the degree of satisfaction expressed by both partners. The data collected allowed the conclusion that self-observation of mucus changes observed at the opening of the vagina did permit identification of the fertile period, as intercourse outside that period had a low probability of resulting in pregnancy (0.4%o per cycle). No evidence was obtained to support the claim that the method can be used to select the sex of a child by timing intercourse in relation to the mucus discharge. It can be concluded from this study, and from other published data, that the ovulation method may permit identification of the fertile period, that it can be learned regardless of educational level, and that the method failure rate is low in developing countries. The majority of pregnancies occurring during the study were the result of a conscious departure from the rules, emphasizing that the successful use of the method requires motivation and shared responsibility by both partners. Gossypol acetic acid: WHO reference material A quantity of highly purified gossypol acetic acid has been prepared by a scientist in China as part of a WHO research programme on gossypol, and is available in lots of 25 mg, 1 g, and 5 g. The material is for animal and chemical experiments only and not for human use. Samples of this material are available for distribution to the scientific community for use in studies designed to help elicit the mode of action and other properties of gossypol acetic acid. These samples will be made available to scientists on receipt of a request accompanied by a brief protocol describing the nature and purpose of the experiments to be carried out. The protocol should indicate justification for the amount of material being requested; it should be borne in mind that the quantities available are limited. Please address requests to: The Task Force Manager, Methods for the Regulation of Male Fertility, Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, 1211 Geneva 27, Switzerland. The WHO Special Programme of Research, Development and Research Training in Human Reproduction should be acknowledged in any publication arising from the use of this material. 46 Bulletin de l'Organisation mondialede la Santi, 63 (1): 47-50 (1985) © Organisation mondiale de la Sant6 1985 Activites scientifiques OMS Souches internationales de r6f6rence de Laishmania La sixieme Reunion du Groupe de travail scienti- fique de la composante leishmaniose du Programme special PNUD/Banque mondiale/OMS de recherche et de formation concernant les maladies tropicales s'est tenue a Montpellier (France) du 9 au 11 juillet 1984, a la suite du deuxieme Symposium international sur la taxonomie et la phylogenie des Leishmania. Cette reunion avait pour objectif l'etablissement d'une liste de souches internationales de reference et la coordination des activites de divers centres parti- cipant a l'identification des Leishmania. Les souches internationales de reference, qui seront utilis6es comme etalons pour l'identification et la caracteri- sation des Leishmania, ont e choisies selon les criteres suivants: 1. Pour chaque taxon, il devra y avoir au moins une souche correspondant a la designation du taxon representant le tableau clinique typique de la maladie dans une region geographique donn&e, et dont un vecteur hautement probable a ete identifie. 2. Chaque souche de reference devra avoir 6t6 etudiee de facon approfondie, figurer dans de nombreuses publications et etre caracterisee de preference par au moins deux techniques reconnues d'identification des Leishmania. 3. Chaque souche de reference devra avoir (dans la mesure du possible) des parametres distinctifs representatifs du taxon, qui seront par exemple des caract6ristiques morphologiques, biochimiques et immunologiques, la virulence vis-a-vis cah8tes d6finis, etc. Apres examen d6taille des renseignements connus sur les mat6riels actuellement disponibles, des souches internationales de reference de Leishmania ont e choisies (voir tableau 1). Le Groupe a en outre formule les recommandations suivantes: 1. Tous les laboratoires responsables des souches internationales de r6ference de Leishmania (labora- toires de ref6rence) devront utiliser le systeme de codification recommand6 par un Comit6 OMS d'experts sur les leishmanioses. a ' OMS, S6rie de Rapports techniques, No 701, 1984 (Les leishmanioses: rapport d'un Comit6 d'experts de I'OMS). 2. Les souches internationales de reference devront etre distribuees A tous les laboratoires de reference. En outre, elles devront etre deposees aupres de l'American Type Culture Collection, Rockville, MD, Etats-Unis d'Amerique, en vue d' une distribution plus large aux chercheurs interesses. 3. Les termes "souche", "stock" et "isolement" devront etre utilises comme il a ete defini pour les trypanosomes. b 4. Si possible, I'analyse par caracterisation des isoenzymes, I'analyse par les anticorps monoclonaux et l'analyse de l'ADN devront etre executees sur les memes souches aux fins de comparaison. 5. Une fiche intitulee "Fiche internationale de demande d'identification de Leishmania" a ete elabor6e au cours de la reunion (tableau 2); il est recommande A tous les laboratoires de reference de l'utiliser. La fiche remplie devra accompagner tous les materiels envoyes aux fins d'identification. Les laboratoires de reference sont encourages A utiliser le traitement automatique des donn6es pour gerer leur cryobanque et pour elaborer un logiciel normalise leur permettant de proceder a l'echange electronique de donn&es. 6. On devra s'efforcer de parvenir A un accord sur les methodes d'analyse (matrices d'identite, dendro- grammes) pour le calcul des distances genetiques et l'etablissement de la taxonomie numerique. L'emploi d'un logiciel normalise devra faire l'objet d'une attention particuliere. 7. Des donn&es descriptives et retrospectives (renseignements cliniques et biologiques) devront etre fournies lors de chaque livraison de souches de Leishmania. Le Groupe a egalement formule des recomman- dations sur les methodes d'exp6dition des specimens, sur la preparation de protocoles detailles pour les methodes d'identification, sur les modalites de notification par les laboratoires de ref6rence, sur la marche a suivre en vue de l'etablissement de nouveaux laboratoires de reference, et sur les modes de finance- ment.' b Bulletin de l'Organwsation mondiale de la Sante, 56: 467-480(1978). c Le rapport int6gral de la Reunion peut etre obtenu sur demande aupres du Programme sp6cial PNUD/Banque mondiale/ OMS de recherche et de formation concernant les maladies tropicales, OMS, 1211 GenEve 27, Suisse. -47- 48 ACTIVITES SCIENTIFIQUES OMS Tableau 1. Souches de Leishmania examin4es par le Groupe de travail scientifique en vue de l'6tablissement de souches internationales de r6f6rence Espbce D6signation de la souche Analyse par: Remarques ADNk ISOZC MABc L. donovanidonovani MHOM/IN/80/DD8b + + - lnfectieuse pour le hamster L. donovani infantum MHOM/TN/80/LEM235 b - + - Infectieuse pour le hamster L. donovani s. sp. MHOM/ET/67/L82 + + + Infectieuse pour le hamster L. donovani chagasia MHOM/BR/74/M2682 b + + + Infectieuse pour le hamster L. major MHOM/SU/73/5-ASKH b + + - Infectieuse pour le hamster L. major MHOM/IL/67/Jericho II + + + Infectieuse pour le hamster L. major MRHO/SU/59/P + + + Infectieuse pour le hamster L. tropica MHOM/SU/74/K27b - + L. tropica MHOM/SU/60/LRC-L39 + + + L. aethiopica MHOM/ET/72/Ll00b + + + L. mexicana mexicana MHOM/BZ/82/BEL2 1 b + + + Infectieuse pour le hamster L. mexicana mexicana MNYC/BZ/62/M379 + + + Infectieuse pour le hamster L. mexicana amazonensis MHOM/BR/73/M2269 b + + + Infectieuse pour le hamster L. mexicana amazonensis IFLA/BR/67/PH8 + + + Infectieuse pour le hamster L. mexicana pifanoia MHOM/VE/57/LL1 b + + L. mexicana garnhamia MHOM/VE/76/JAP78 b + + + L. mexicana venezuelensis MHOM/VE/00/H 17 b _ + + Infectieuse pour le hamster L. brazilensis braziliensis MHOM/BR/00/LTBOO1 4(L) b + + + Infectieuse pour le hamster L. braziliensis braziliensis MHOM/BR/75/M2903 + + + Infectieuse pour le hamster L. braziliensis panamensis MHOM/PA/71 /LS94 b + + L. braziliensis guyanensis MHOM/BR/75/M4147 b + + + Infectieuse pour le hamster L. enriettii MCAV/BR/45/L88 + + + Infectieuse pour le hamster et le cobaye L. hertigi hertigi MCOE/PA/65/C8 + + + L. hertigi deanei MCOE/BR/74/M2674 - + - Infectieuse pour le hamster L. aristidesi MORY/PA/69/GML3 + + + L. gerbilli MRHO/CN/60/GERBILLI + + a L'appartenance de ces souches a des taxa distincts est controversee. b Ces souches sont design6es comme souches internationales de reference; les autres souches indiquees ici ont ete dOment etudi6es et caracteris6es, mais ne satisfont pas A tous les criteres de selection. ' ISOZ = isoenzymes; MAB = anticorps monoclonaux. Planification familiale naturelle par la m6thode de d6tection de l'ovulation (m6thode Billings) Parmi les methodes actuelles de regulation de la fecondite figurent les methodes basees sur la continence pendant la periode feconde du cycle menstruel; ces methodes sont couramment appelees methodes de planification familiale naturelles. L'une d'entre elles, la methode Billings de detection de l'ovulation, repose sur l'aptitude individuelle de la femme a determiner sa periode feconde en observant les modifications de consistance et d'aspect des secretions normales recueillies A l'entree du vagin. Comme il n'existe que tres peu de donnees trans- culturelles sur l'aptitude des femmes a deceler ces modifications et sur l'efficacite de la methode de detection de l'ovulation pour prevenir les grossesses non desirees, l'Organisation mondiale de la Sante a entrepris une etude pilote dans cinq pays pour repondre a ces questions. Les cinq centres choisis etaient Auckland (Nouvelle-Zelande), Bangalore (Inde), Dublin (Irlande), Manille (Philippines) et San Miguel (El Salvador). Les resultats detailles de cette etude ont ete publi6sd et ses principales conclusions d Fertility and sterility, 36: 152-158, 591-598 (1981); 40: 773- 778 (1983); 41: 593-598 (1984). Pour plus de renseignements et/ou pour recevoir des exemplaires de ces articles, s'adresser au Directeur du Programme special de recherche, de developpement et de formation a la recherche en reproduction humaine, Organisation mondiale de la Sant6, 1211 Geneve 27, Suisse. 49ACTIVITES SCIENTIFIQUES OMS Tableau 2. Fiche internationale de demande d'identification de Leishmania A remplir dans toute la mesure du possible. Date:. 1. Resultats a envoyer a: Nom:. Adresse. 2. Personne ayant realise l'isolement: Nom:. Adresses. 3. Numero de code de l'isolement/du stock.4.Autres numAros de code:...... ................... Autres numeros de code: 5. Pays et lieu ou l'infection a ete contractee:..................................................................................................................... 6. AnnP eon 'infection a ete contractee: .N .................................................................... 7. Type de maladie chez l'homme ou l'animal: Viscerale CutanAediffuse.Autres............................. CutanAee .................................. Leishmaniose recidivante . Muqueuse ................................... Leishmaniose dermique post-kala azar.................................... 8. Nombre de lesions cutanees: Unique ..Multiples . . 9. Paysdet l'ieuolem ne cti(or nea ....................................................................................................................................... 10. Comment le micro-organisme a-t-il ete isold? a) Culture: dens quel milieu? Le micro-organisme pousse-t-il facilement? Oui Non b6 ) Inoculation a l'animal: Espace, souche...................................................................................................................... 11. STockdpralade chez I'hommeNom uInmalad:.Desrou emn dl'neto................................ Ctnedfue.............................................................................. b) Existe-t-il de Ia leishmaniose humaine dans Ia rngion? Oui. e Non c ) Si oui: Viscerale.Muqueue ................................. Cud nAe.CutanAe dife............... Mutpe.........tanee...... 9 St deE s oleme nt................ .........................................................................................................................................130. S ockenprlev mchezeophabotome:ati io b) Site de 'infection: Intestin anterieur .croorganismoyen.pousseti nposterieur . b)Inocultion A An altrpbe............ ............................ .......................................................................................... 14. Remarques complementaires: .......................................................................................................................................................................... ............................................................................................................................................................................... .................................................................................................................................................................................... ACTIVITtS SCIENTIFIQUES OMS sont resumees ci-dessous. Au total, 869 femmes normalement reglees, de fecondite prouvee, ont participe a une premiere etude destinee a evaluer l'aptitude individuelle a deceler la periode feconde. L'age moyen des femmes etait de 30 ans, et elles etaient de niveaux socio-economiques et de niveaux d'etudes tres divers, puisque le groupe comptait 13%o d'analphabetes et 8%o de femmes ayant fait des etudes superieures. Le nombre moyen de grossesses anterieures etait de 3,9 et ces femmes n'avaient jamais experimente la methode de detection de l'ovulation. Au cours du premier cycle suivant l'expose de la methode par un enseignant speciale- ment forme, 93% des femmes en moyenne ont ete capables d'identifier les signes de la periode feconde lies a la glaire cervicale. Des antecedents d'ecoule- ments vaginaux pathologiques ne modifiaient pas l'aptitude de la femme a reconnalitre l'aspect de la glaire. Pendant la phase d'apprentisage, la methode de detection de l'ovulation par l'examen de la glaire cervicale exige 17 jours de continence sur un cycle durant en moyenne 29 jours. Pendant cette phase, 5% de femmes participant a l' etude ont eu une grossesse non desiree. Sur les 765 femmes qui ont appris correctement la methode, 725 (88%o) ont participe a une etude de l'efficacite de la methode portant sur 13 cycles (environ 1 an). Le taux global de grossesses a ete de 22,5 pour 100 annees-femme (13,8 'a Manille, 19,6 a Bangalore, 19,7 a Dublin, 32,8 a San Miguel et 33,6 a Auckland). On notera que la cause la plus frequente de ces grossesses etait le non-respect delibere des principes de la methode (qui exige une continence rigoureuse pendant la periode feconde); sur ce taux de 22,5 grossesses, 15,4 s'expliquent par ce comporte- ment. Le taux moyen de grossesses lorsque la methode est scrupuleusement observee (taux d'echec de la m'thode) a ete de 2,8 pour 100 annees-femme (0 a Bangalore, 0 a San Miguel, 1,1 a Manille, 5,1 a Dublin et 9,4 a Auckland). La raison des taux d'echec eleves dans les deux pays developpes est peu claire. La probabilite moyenne d'abandon de l'e'tude etait de 35,60o, allant de 25,8qo a Bangalore 'a 48,2% a Auckland. Le taux moyen de grossesses a ete plus faible chez les femmes desirant limiter la taille de leur famille (17,1%qo) que chez celles qui desiraient utiliser la methode pour espacer les naissances (22,2%). Le taux moyen d'abandon a egalement e plus faible chez les "limiteuses" (29,1%) que chez les "espaceuses" (43q%). Les taux d'avortements spon- tanes et de malformations congenitales n'etaient pas differents des taux correspondants observes dans la collectivite ni de ceux associes a d'autres methodes de regulation de la fecondite, bien que cette etude ne comporte pas un effectif suffisant pour repondre a ces questions avec certitude. II semblerait que l'utilisation reussie de la methode de detection de l'ovulation depende du degre de satisfaction exprime par les deux partenaires 'a son egard. Les donnees recueillies permettent de conclure que l'auto-obser- vation des modifications de la glaire cervicale recueillie 'a l'entree du vagin permet de reperer la periode feconde, puisque les rapports sexuels en dehors de cette periode n'ont qu'une faible proba- bilite d'entrainer une grossesse (0,4% par cycle). Rien ne montre en revanche que cette methode puisse etre utilisee pour choisir le sexe de 1'enfant en ayant des rapports sexuels 'a un moment ou 'a un autre de la periode feconde. On peut conclure de cette etude ainsi que d'autres donnees publiees que la methode de detection de l'ovulation peut permettre d'identifier la periode feconde, qu'elle peut etre apprise quel que soit le niveau d'etude et que son taux d'echec est faible dans les pays en developpement. La plupart des grossesses survenues au cours de l'etude etaient dues au non- respect delibere des principes de la methode, ce qui montre que, pour qu'elle soit appliquee avec succes, il faut que les partenaires soient tous deux motives et responsables. Gossypol/acide ac6tique: substance OMS de r6f6rence Une certaine quantite de gossypol/acide acetique hautement purifie a et preparee en Chine par un chercheur travaillant dans le cadre d'un programme OMS de recherche sur le gossypol, et est disponible sous forme de lots de 25 mg, I g et 5 g. Cette substance est destinee exclusivement La 1'experimentation sur l'animal et a 1'exp6rimentation chimique et non a l'emploi chez l'homme. Des echantillons de cette substance peuvent etre distribues a la communaute scientifique pour etre utilises dans des etudes destinees a elucider le mode d'action et les autres proprietes du gossypol/acide acetique. Ces echantillons seront fournis aux chercheurs sur demande accompagn&e d'un protocole resume decrivant la nature et l'objet des experiences envisagees. Le protocole devra justifier les quantit6s de substance demandees. On voudra bien noter que les quantites disponibles sont limitees. Les demandes devront etre adressees a: Directeur du groupe special, Methodes masculines de regulation de la fecondite, Programme special de recherche, de developpement et de formation La la recherche en reproduction humaine, Organisation mondiale de la Sante 1211 Geneve 27, Suisse. Le Programme special OMS de recherche, de developpement et de formation a la recherche en reproduction humaine devra etre cite dans toute publication rendant compte de l'essai de cette substance. 50