RESUMO
A new experiment, the forward directed quantitative gamma-HCCH-TOCSY for the measurement of the conformation of the five-membered ribosyl unit in RNA oligonucleotides, is presented. The experiment relies on quantification of cross peak intensities caused by evolution of CH, CH-dipole-dipole cross correlated relaxation in non-evolution periods and the resolution enhancement obtainable in forward directed HCC-TOCSY transfer. Cross correlated relaxation rates are interpreted to reveal the sugar conformation of 22 out of 25 nucleotides in an isotopically labelled 25-mer RNA. The results obtained with this new method are in agreement with the conformational analysis derived from 3J(H,H) coupling constants.
Assuntos
Ressonância Magnética Nuclear Biomolecular/métodos , Oligorribonucleotídeos/química , Configuração de Carboidratos , Modelos Teóricos , Ressonância Magnética Nuclear Biomolecular/instrumentação , Conformação de Ácido Nucleico , SoluçõesAssuntos
Dietilestilbestrol/efeitos adversos , Morte Fetal/induzido quimicamente , Doenças do Recém-Nascido/induzido quimicamente , Doenças Vaginais/induzido quimicamente , Aborto Espontâneo/tratamento farmacológico , Quimioterapia Combinada , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Troca Materno-Fetal , Gravidez , Complicações na Gravidez/tratamento farmacológico , Progestinas/administração & dosagemRESUMO
A histologic study was conducted of sagittal sections of the genital tracts of 281 autopsied female stillborns and neonates. The prevalence of vaginal adenosis among 43 offspring exposed in utero to diethylstilbestrol (DES) was 70%, a frequency 18 times greater than the 4% prevalence among 159 unexposed offspring. The relationship of the prevalence of vaginal adenosis to the gestational age at initial exposure was highly significant: 81% of those first exposed during the period of vaginogenesis had adenosis, whereas none exposed after 21 weeks' gestation had adenosis (P1 = 1 X 10(-4)). The relationship of the prevalence of vaginal adenosis to the total dose of DES prior to 22 weeks' gestation also was significant (P1 = 0.02), and this relationship was independent of gestational age at first exposure (P1 =0.01). In contrast, the prevalence of adenosis among 23 offspring exposed to steroidal estrogens and progestins was about the same as that among the unexposed offspring. Vaginal adenosis was unrelated to the complications of pregnancy for which the hormones were given, the calendar year of birth, and the gestational age at delivery.
Assuntos
Dietilestilbestrol/efeitos adversos , Estrogênios/efeitos adversos , Doenças do Recém-Nascido/induzido quimicamente , Progestinas/efeitos adversos , Vagina/efeitos dos fármacos , Relação Dose-Resposta a Droga , Feminino , Morte Fetal/patologia , Idade Gestacional , Humanos , Hiperplasia/induzido quimicamente , Recém-Nascido , Troca Materno-Fetal , Gravidez , Complicações na Gravidez/tratamento farmacológico , Vagina/embriologia , Vagina/patologiaRESUMO
The continued high prevalence of oral contraceptive (OC) use by young women warrants the careful study of these agents. At present, it appears that the risk of benign breast disease is reduced by use of OCs. This effect seems to be greater for fibrocystic disease than for fibroadenoma. Available information suggests that, as yet, OC use has not had any effect on breast cancer risk. The recent slight rise in breast cancer rates in younger women has not been shown to be due to OC use. The relationship between OCs and breast cancer may not become clear for another 5 to 10 years because of the long latent period of this disease. Meanwhile, for reasons presented, it would seem wise not to prescribe OCs for women with a history of benign breast disease and to withdraw them from women who develop these conditions.