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Biomedical subjects

H A Bern

Publications and source records attributed to H A Bern.

At least 163 records · Page 9Linked to original sources
PubMed1977

Biological actions of human somatotrophin and its derivatives on mouse mammary gland and teleost urinary bladder.

These studies are concerned with the structural and functional evolution of the ancestrally related pituitary prolactins and somatotrophins. Prolactin-like biological activities of human somatotrophin (hGH) and its peptide fragments were bioassayed in vitro on the mouse mammary gland and the teleost urinary bladder. Plasmin modified-hGH was as active as hGH in both bioassays. The NH2-terminal 134-residue fragment possessed about 10% of the lactogenic and urinary bladder potency of hGH, whereas the CO2H-terminal 51-residue fragment was inactive at the concentrations observed. These results suggest that the same regions of primary structure are responsible for the prolactin-like actions of hGH on the target organs of lower and higher vertebrates. Alteration of the tertiary structure of hGH, human chorionic somatomammotrophin, and ovine prolactin by performic acid oxidation destroys the mammary gland activities of these hormones.

Animals↗
PubMed1977

Long-term effects of neonatal treatment with progesterone, alone and in combination with estrogen, on the mammary gland and reproductive tract of female BALB/cfC3H mice.

Neonatal female mice of the BALB/cfC3H strain were given 5 daily injections of 17beta-estradiol and progesterone alone and in combination, beginning within 36 hr after birth. Half of the mice in each group were ovariectomized at 40 days of age, and all were killed at tumor age of at 12 months of age. Mice receiving progesteron (100 mug daily) alone showed ovary-dependent persistent vaginal cornification. When neonatal progesterone and estradiol were given concurrently, the occurrence of persistent vaginal cornification was significantly lower than in mice receiving neonatal estradiol treatment alone. Progesterone alone produced hyperplastic downgrowths and lesions of both vaginal and cervical epithelia, but to a lesser degree than occurred in mice treated neonatally with estrogen. When progesterone was given concurrently with 17beta-estradiol, the incidence of lesions was lower but their severity was greater. The low doses of 17beta-estradiol and progesterone each resulted in an earlier age of onset and a higher incidence of mammary tumors; this also occurred after both combined estrogen-progesterone treatments. In treated mice ovariectomized on Day 40, normal mammary development did not occur and mammary tumors failed to appear, regardless of neonatal treatment. The data indicate a clear effect of neonatal progesterone exposure on both the genital tract and the mammary apparatus of female mice.

Adenocarcinoma↗
PubMed1976

The caudal neurosecretory system. A critical evaluation of the two-hormone hypothesis.

Recent information on the caudal neurosecretory system (urophysis) is collated, with special reference to cellular biology including neural relations, activity and chemistry 8 the biological principles associated with the urophysis, pharmacological analysis of the receptors for these principles, and their possible functions in a physiological sense. The existence of at least two principles, urotensins I and II, is well established. They differ pharmacologically and chemically and may arise from different cell types. At present, osmoregulation, cardiovascular regulation and reproduction are the most likely aspects of organismal physiology wherein these principles may be involved.

Animals↗
PubMed1976

Long-term effects of neonatal steroid exposure on mammary gland development and tumorigenesis in mice.

Newborn female mice of three strains--BALB/cfC3H [mammary tumor virus (MuMTV)-infected], BALB/c, and C57BL (both virus-free)--were given injections of 17beta-estradiol or testosterone, alone or in combination with ovine prolactin, for the first 5 days of life. Half of each group of mice were ovariectomized at 40 days of age, and all mice were killed between 6 and 16 months of age. Mammary glands of BALB/cfC3H mice receiving steroid hormones were better developed than those of mice not receiving steroids. Androgen induced a higher incidence of grossly dilated ducts and secretion-filled alveoli. Mammary nodule and tumor incidences were higher in steroid-treated mice than in controls; androgen resulted in higher incidences than did estrogen. The age of onset of mammary tumors was also earlier after neonatal steroid treatment. In BALB/c mice, neonatal injections of estrogen induced some alveolar development of the mammary gland; neonatal injections of ovine prolactin had a greater effect. The mammary glands of C57BL mice did not show any evidence of stimulation by neonatal hormone treatment, which indicated the probability of strain differences. However, no nodules or tumors occurred in these MuMTV-free strains. Therefore, MuMTV was essential for neoplastic mammary responses to neonatal hormone treatment. Ovariectomy prevented alveolar development and abnormal changes in the mammary glands of all groups, thus indicating that ovary-independent alterations in the mammary gland were not induced by neonatal steroid treatment. We concluded that neonatal steroid exposure resulted in increased mammary tumor risk in mice, but only in the presence of both MuMTV and ovaries.

Animals↗
PubMed1976

Use of the neonatal mouse in studying long-term effects of early exposure to hormones and other agents.

The neonatal female mouse is considered as a model for studying the long-term consequences of exposure of the human fetus and neonate to hormones and other agents. Parallelism is noted between the results of administration of sex steroids and diethylstilbestrol (DES) to newborn mice and the phenomenon of vaginal cancer in young women whose mothers were given DES for threatened abortion. The progression of the neonatally steroid-treated mouse lesions from persistent vaginal cornification through hyperplastic lesions to tumors is described. The interaction of progesterone with estradiol is considered (lesions are fewer but more severe at 12 months of age following neonatal exposure to a combination of estradiol and progesterone), and the ability of neonatal progesterone treatment alone to result in cervicovaginal lesions in intact mice is emphasized. All steroids result in increased mammary tumor incidence and lowered age of tumor onset in intact mice bearing the mammary tumor virus; both the ovary and the virus are required for these effects. Possible ramifications of early perinatal exposure are indicated in regard to the male, to nongenital structures, to the endocrine system generally, and to immunologic mechanisms.

Animals↗
PubMed1975

Adrenocortical function: corticosterone levels in female BALB/c and C3H mice under various conditions.

A diurnal rhythmicity in plasma corticosterone levels was demonstrated in female BALB/cCrgl and C3H/Crgl mice, with and without mammary tumor virus. Removal of the adrenals followed by metopirone treatment reduced circulating corticoid to non-detectable levels in C3H but not in BALB/c mice. Dexamethasone strains. Neonatal exposure to exogenous hormones failed to cause any obvious change in corticoid levels. Bilateral ovariectomy of these neonatally treated mice at 40 days of age resulted in a subsequent lowering of plasma corticoid levels when compared with intact animals.

Adrenal Cortex↗