James R. Harmon

Characterization of estrogen binding in uterine cytosol from the fetal rhesus monkey

Cytosol receptor binding of 17 beta-estradiol was demonstrated in the uterus of the late-gestation, fetal rhesus monkey. Sucrose density gradient analysis performed in low-ionic strength buffer indicated a binding component with a sedimentation coefficient of 6-7 S. Under high-ionic strength conditions, the component shifted to a sedimentation coefficient of approximately 4 S. The specificity of the receptor for estrogens was indicated by inhibition of [3H]estradiol binding by both natural and synthetic estrogen competitors, but not by progesterone. Saturation analysis indicated a high degree of nonspecific binding with saturation of specific binding occurring at 2-3 nM. Computer-assisted Scatchard analysis of the data resolved a one-receptor model having a limited number of binding sites and an apparent dissociation constant of 10(-10) M. The interaction of estrogens with the fetal uterus and the cellular mechanisms which permit this interaction are discussed in relation to the development of models for extrapolation to the human.

Acute oral toxicity of n-2-fluorenylacetamide (2-faa) in several strains of mice.

Summary The oral LD50/7 day of 2-FAA has been determined in both sexes of the following strains of mice: CD-1, C57BL/6Cr, C57BL/6j, and BALB/cj. Symptoms of toxicity included: lethargy, sedation, loss of righting reflex, circling, orange-red urine, bladder concretions and paralysis with all limbs rigidly extended. Deaths peaked between 48 and 72 hr. Particle size was shown to affect the LD50/7 day in CD-1 mice. His-topathological examination of the tissues indicated they were essentially normal. The authors thank S. Poiley for the C57BL/6Cr mice used in this study, and Drs. W. Jacques and C. Frith for the histopathological evaluations.

Estimation of the LD1 and extrapolation of the LD0.1 for five organophosphate pesticides

The oral LD50,s for 5 Organophosphate pesticides have been determined in CD-1 strain male and female mice. The values in mg/kg are: Triohlorfon, 800 and 800; Naled, 409 and 330; Dichlorvos, 139 and 133, GC6506, 23.4 and 17.8; Fospirate, 225 and 263 respectively. Toxicity was greater in males with Fospirate and greater in females with Naled and GC6506. The predicted LD1s and the extrapolated LD0.1s have been determined for the 5 organophosphates from an unbalanced design, loaded heavily toward the lower end of the dose-response curve. It has been shown that the slopes of the curves obtained with 50, 100 and 660 animals are parallel for all compound except Fospirate in the 660 mouse experiments. This is probably related to excessive female deaths in the upper segment of the dose-response curve. Sex dependent lethality was observed with Trichlorfon, Dichlorvos and Fospirate with the males being more susceptible than the females except in the case of Fospirate where there was a reversal at the LD50 with greater susceptibility in the females. The conditions for obtaining accurate results in such experiments have been established. The implications of human exposure to low levels of the environmental pollutants have been discussed.ZusammenfassungDie orale LD50 für 5 Organophosphat-Pesticide wurde für männliche und weibliche CD-1 Mäuse bestimmt. Die Werte in mg/kg sind: für Trichlorfon 800 und 800; für Naled 409 und 330; für Dichlorvos 139 und 133, für GC6506 23,4 und 17,8; und für Fospirate 225 und 263. Die Fospirate Toxicität ist größer in männlichen Mäusen; Naled und GC6506 ist toxischer in weiblichen CD-1 Mäusen. Die vorausgesagten LD0.1s und die extrapolierten LD0.1s wurden bestimmt für die 5 Organophosphate mittels einer unbalanzierten Versuchsanordnung; d. h. dem unteren Teil der Dosis-Wirkungs-Kurve wurden mehr Tiere zugeordnet. Es wurde gezeigt, daß der Verlauf der mit 50, 100 und 660 Tieren erhaltenen Kurven für alle Verbindungen mit Ausnahme von Fospirate im Experiment mit 660 Mäusen parallel ist. Die Fospirate Ausnahme ist vermutlich bedingt durch die hohe Mortalitätsrate der weiblichen Mäuse im oberen Abschnitt der Kurve. Eine geschlechtsabhängige Letalität wurde beobachtet; männliche Mäuse sind empfindlicher gegenüber Trichlorfon, Dichlorvos und Fospirate als Weibchen. Fospirate bewirkte eine größere Letalität in Weibchen in der Nähe der LD50. Die Bedingungen zur Gewinnung akkurater Resultate in solchen Experimenten wurden beschrieben. Die Folgen einer Exponierung von Menschen gegenüber kleinen Mengen von Umwelts-Verbindungen wurden diskutiert.

Ninety day subchronic toxicity of N-2-fluorenylacetamide (2-FAA) in C57BL-6j and BALB-cStCr1BR mice.

Summary Subchronic (90 day) toxicity of N-2-fluorenylacetamide has been investigated in male and female C57BL/6j and BALB/cStrCr1BR strain mice. No signs of toxicity were observed with dietary levels ranging from 0.001-0.05% 2-FAA. A dose dependent urinary bladder epithelial hyperplasia was seen in both strains with the males being more susceptible than the females. Squamous metaplasia of the urinary bladder was observed in the BALB/c mice with the male response being double that of the female. One urinary bladder carcinoma was found in a BALB/c male at the 0.025 and 0.05% 2-FAA levels. Adrenal gland spindle cell hyperplasia was more pronounced in the females of both strains. Males of both strains had urinary bladder concretions. No other significant histopathological changes were observed.

Estrogen Receptor Characterization Following Selective Sedimentation Separation of Estrogen-Binding Components In Immature Rat Uterine Cytosol

AbstractCharacterization of a specific estrogen receptor (ER) in fetal and early postnatal rat uterine cytosol is complicated by the presence of other high-affinity estrogen-binding components, such as alpha-fetoprotein (AFP). In an attempt to circumvent their influence, we have employed the selective sedimentation of unlabeled cytosol through sucrose gradients, followed by the analysis of [3H]estradiol binding to a pool of fractions comprising the ER region, as well as to individual gradient fractions. As the amount of AFP present in 21-day-old rats is sufficiently low to permit ER characterization by conventional methodology, we have validated the selective sedimentation method by comparing its results with those obtained conventionally. Though conventional gradient analysis revealed only one estrogen-binding component, saturation and binding inhibition analyses indicated the presence of multiple components, identified as AFP and the ER. These conclusions were supported by results from labeling individu...