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Biomedical subjects

H A Bern

Publications and source records attributed to H A Bern.

At least 91 records · Page 5Linked to original sources
PubMed1986

Frequent occurrence of polyovular follicles in ovaries of mice exposed neonatally to diethylstilbestrol.

The occurrence of polyovular follicles (PF) was examined at 10-34 days of age in the ovaries of BALB/cCrgl female mice given five daily injections of 0.1 microgram diethylstilbestrol (DES), 2 micrograms DES, 100 micrograms progesterone (P), 137 micrograms 17 alpha-hydroxyprogesterone caproate (HPC), 20 micrograms testosterone (T), 20 micrograms 5 alpha-dihydrotestosterone (5 alpha-DHT), or oil vehicle alone starting on the day of birth, and of C57BL/Tw females given five neonatal injections of 1 microgram DES, 20 micrograms 17 beta-estradiol (E2), 50 micrograms 5 alpha-DHT, 50 micrograms 5 beta-DHT, or the vehicle alone. Ovaries of 30-day-old C57BL mice given five daily injections of 1 microgram DES starting at 3-25 days of age were also examined. PF incidence (% of PF per ovary) and PF frequency (% of mice with PF) were significantly greater in BALB/c mice receiving injections of DES, P, HPC, and T than in the controls. In DES-treated mice at 34 days, PF incidence (2-13 oocytes/follicle) was 120-340 times higher than in the controls. BALB/c mice treated with T, P, and HPC showed PF incidence (two to four oocytes/follicle) three- to six-fold higher than in the controls. In 30-day-old C57BL mice treated with T, E2, and DES, PF incidence also increased by two- to 50-fold. 5 alpha-DHT and 5 beta-DHT failed to increase PF incidence. PF incidence was significantly increased only when neonatal DES treatment was begun on days 0 to 3, but was reduced when started at days 10-25.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Cardiovascular effects of urotensin II in anesthetized and pithed rats.

Gillichthys urotensin II (GUII; 1.5-150 nmol kg-1) reduced blood pressure in anesthetized rats, diastolic pressure being reduced to a greater extent than systolic. The effect was slow in onset (peak at 4-5 min) and longlasting (up to 60 min), and was accompanied by a reflex tachycardia. The hypotension was not blocked by propranolol or by mepyramine. In pithed rats, GUII (150 nmol kg-1) reduced the pressor responses to sympathetic nerve stimulation, noradrenaline, and Arg-vasopressin. Somatostatin (150 nmol kg-1) had no effect on the sympathetic pressor response but reduced heart rate. It is concluded that GUII is a vasodilator in the rat, an action not shared with somatostatin.

Anesthesia↗
PubMed1986

In vitro effects of somatostatin and urotensin II on prolactin and growth hormone secretion in tilapia, Oreochromis mossambicus.

The control of release of two recently characterized forms of prolactin (PRL) of molecular mass 24 and 20 kDa was investigated. The rostral pars distalis of male tilapia was incubated singly in a hypotonic modified Krebs-Ringer bicarbonate medium in order to stimulate PRL release; for comparison, the proximal pars distalis containing growth hormone (GH) cells was incubated in isotonic medium with or without 1 microgram/ml cortisol to stimulate GH release. The release of both PRLs and GH into the medium was measured by sodium dodecyl sulfate (SDS)--polyacrylamide gel electrophoresis followed by densitometry. Both somatostatin and synthetic (Gillichthys) urotensin II, a partial somatostatin homolog and analog from the teleost caudal neurosecretory system, significantly inhibited the release of both PRLs. Somatostatin significantly inhibited GH release, but urotensin II had no significant effect.

Animals↗
PubMed1986

Both somatostatin and the caudal neuropeptide, urotensin II, stimulate lipid mobilization from coho salmon liver incubated in vitro.

The direct effects of somatostatin-14 (SRIF; synthetic ovine) and the fish caudal neuropeptide, urotensin II (UII; synthetic Gillichthys), on fatty acid (FA) release and on lipolytic enzyme (triacylglycerol lipase) activity were determined on coho salmon liver slices incubated in vitro. FA release was continuously measured by pH-stat titration. Additionally, gas chromatographic analysis of the incubation medium was performed to determine the type and relative composition of medium fatty acid constituents. SRIF and UII both stimulated FA release in a dose-dependent manner; the two peptides appeared to stimulate FA release in an equimolar manner. Maximal response was obtained at 1 X 10(-5) M; ED50 was approximately 2 X 10(-7) M. SRIF-stimulated FA release did not result in differential secretion of any particular FA type. Tissue triacylglycerol lipase activity was significantly enhanced by addition of UII or SRIF (2 X 10(-6) M). Dibutyryl cAMP and IBMX both stimulated FA release and lipase activity; dbcAMP stimulated FA release in dose-dependent manner. These results indicate that SRIF and UII directly enhance lipid mobilization from salmon liver slices and suggest that SRIF- and UII-stimulated lipid mobilization from salmon liver slices is mediated through cAMP.

1-Methyl-3-isobutylxanthine↗
PubMed1986

Restoration of normal morphology and estrogen responsiveness in cultured vaginal and uterine epithelia transplanted with stroma.

We have investigated the capacity of vaginal and uterine epithelia (VE and UE) to reexpress normal morphology and hormone responsiveness following cell culture. VE and UE from adult ovariectomized mice were grown in a collagen gel matrix with serum-free medium for 7-10 days. Proliferation of these cells occurs in the absence of 17 beta-estradiol and is not stimulated by 17 beta-estradiol; the VE usually does not keratinize or stratify in vitro. Cultured VE and UE were recombined with homologous vaginal or uterine stroma (VS and US, respectively) and these recombinants were grown under the renal capsule of female hosts for 4 weeks. The epithelium of the VS + VE recombinants cycled, proliferated and stratified in response to estrogen and mucified normally in response to progesterone. The UE that was grown in vivo with cultured US also showed normal morphology and estrogen responsiveness. These changes in the UE and VE were not simply a result of return to the in vivo environment, as epithelia alone in collagen gels transplanted under the renal capsule did not survive. These results indicate that both VE and UE, which are not estrogen-dependent in vitro, reexpress their estrogen dependency and normal morphology when recombined with homologous stroma and grown in vivo. Thus, the changes these cells show when grown in culture are the result of altered conditions in vitro rather than an irreversible alteration in the cells themselves or the selection of specific subpopulations that are not mitogenically or morphologically responsive to estrogen under any condition.

Animals↗
PubMed1986

Effect of chronic exposure to an acidified environment on the urophysis of the brook trout, Salvelinus fontinalis.

The activity of the caudal neurosecretory system including its neurohemal organ, the urophysis, was assessed in six populations of brook trout (Salvelinus fontinalis)--three from acidified lakes and three from nonacidified lakes (Laurentides Parc, Québec). The acidified lakes were characterized by low pH (mean annual value around 5.5), poor buffering capacity and low conductivity. The activity of the caudal neurosecretory cells was evaluated by morphometry (cell and nuclear sizes). The urophysial content of the neuropeptide urotensin II was measured by isolated trout rectum bioassay. Fish from acidified lakes showed markedly larger cell and nuclear sizes and a lower content of urotensin II than fish from nonacidified lakes. An acidified environment appears to stimulate the synthetic activity of caudal neurosecretory neurons and promote release of urotensin II from the urophysis. This modified endocrine activity in brook trout may reflect adjustment to adverse external ionic conditions.

Animals↗
PubMed1985

Estrogen and progestin receptors in mouse vaginal epithelium and fibromuscular wall.

Both sodium molybdate and Percoll density gradient stabilize the hormone-binding capacities of the estrogen and progestin receptors and individually increase the recovery of these receptors in prepared cytosols of the separated mouse vaginal epithelium and fibromuscular wall. Their effects are additive. The concentrations of estrogen receptors are similar in the epithelial and fibromuscular compartments, whereas progestin receptor concentrations are higher in the epithelium.

Animals↗
PubMed1985

Changes in the rates of glycogenesis, glycogenolysis, lipogenesis, and lipolysis in selected tissues of the coho salmon (Oncorhynchus kisutch) associated with parr-smolt transformation.

The rates of glycogenesis, glycogenolysis, lipogenesis and lipolysis were determined in selected tissues of the coho salmon, Oncorhynchus kisutch, during the period of parr-smolt transformation between February 1983 and June 1983. Glycogen synthesis in the liver, measured by uridine diphosphate formation, decreased 54% from initial levels. Liver glycogen phosphorylase a activity increased by 66%. Neutral lipid (sterol) and fatty acid synthesis in the liver and mesenteric fat was measured by tritium incorporation. Fatty acid synthesis in the liver and mesenteric fat decreased by 88% and 81%, respectively, between late February (parrs) and early June (smolts). There was no significant change in the rate of tritium incorporation into liver or mesenteric fat neutral lipids during the sampling period. Lipolytic rates were assessed by measuring the release of 14C-oleic acid from 14C-triolein in the presence of partially purified triacylglycerol lipase enzyme preparations from the liver, dark muscle and mesenteric fat. Liver, dark muscle and mesenteric fat lipase activity increased by 86%, 146% and 289%, respectively, during the sampling period. Increased glycogen and lipid breakdown, and concomitant decreased glycogen and fatty acid synthesis would contribute to the lipid and glycogen depletion observed in salmonid species undergoing parr-smolt transformation.

Adipose Tissue↗
PubMed1985

Responses to salinity and the effect of prolactin on whole animal transepithelial potential in the gobiid teleost, Gillichthys mirabilis.

Whole-animal transepithelial potential (TEP) of the goby, Gillichthys mirabilis, was measured. TEP was the same whether the electrode was implanted in the dorsal muscle or in the peritoneal cavity. TEP response to different salinities was linear from 0 to 100% seawater, and stable from 100 to 200% seawater. TEP decreased significantly in 225 and 250% seawater, and the fish became dehydrated. Plasma Na and Cl concentrations showed a linear relationship with increase in salinity from 0 to 200% seawater. In hypophysectomized Gillichthys, TEP was significantly lower than in sham-operated fish, but hypophysectomized fish with a rostral pars distalis autotransplant showed TEP similar to that of intact fish. Plasma Na and Cl in hypophysectomized fish were lower than in intact and RPD-autotransplanted fish, suggesting that prolactin is involved in maintaining normal whole-animal TEP.

Adaptation, Physiological↗
PubMed1985

In vitro release of growth hormone from the pituitary gland of tilapia, Oreochromis mossambicus.

The release of growth hormone from the proximal pars distalis of the tilapia, Oreochromis mossambicus, was significantly stimulated by cortisol (1 microgram/ml) in an in vitro system. Growth hormone released into the medium and remaining in the tissue was measured by densitometry after gel electrophoresis. Neither triiodothyronine (6.7 ng/ml) nor equimolar concentrations of thyroxin altered the release of growth hormone. In combination with cortisol, triiodothyronine did not alter the effect of cortisol alone.

Animals↗
PubMed1985

Development and validation of a salmon prolactin radioimmunoassay.

A highly specific radioimmunoassay (RIA) for the measurement of prolactin (PRL) in the plasma and pituitary of salmonid fishes was developed using a rabbit antiserum to chinook salmon (Oncorhynchus tschawytscha) PRL. The PRLs purified from chinook salmon and chum salmon (O. keta) pituitaries showed exactly the same competitive inhibition curves in the RIA, regardless of iodination of either hormone. The displacement curves for pituitary extracts and plasma from several salmonids, including chum, coho, and amago salmon, rainbow trout, and Japanese charr, were parallel to the salmon PRL standard, whereas those from the eel, goldfish, carp, and tilapia showed negligible cross-reactivity. Negligible cross-reactivity was also seen with plasma from hypophysectomized rainbow trout or coho salmon. None of the mammalian PRL or growth hormone (GH) preparations, bullfrog PRL, or presumptive chum salmon "gonadotropin" and eel "PRL" cross-reacted in the PRL RIA. Presumptive chum salmon GH showed less than 0.05% cross-reactivity. The RIA sensitivity was less than 0.1 ng of the salmon PRL standard per milliliter. The immunoreactive plasma PRL levels in mature chum salmon were below 1 ng/ml in seawater. The plasma PRL in females increased to about 8 ng/ml 1 day after transfer to fresh water, and high levels (2-4 ng/ml) were maintained during 3-7 days after the transfer. In contrast, when males were transferred to fresh water, an increase in plasma PRL was seen only 1 day after the transfer. A significant decrease in plasma osmolality was observed in both males and females after transfer to fresh water. No change was observed either in plasma PRL or osmolality, when fish were transferred from seawater to seawater.

Animals↗
PubMed1985

Somatostatin-like immunoreactivity in the pituitary and brain of three teleost fish species: somatostatin as a potential regulator of prolactin cell function.

Somatostatin-like immunofluorescence occurs in the hypothalamus and neurohypophysis of three euryhaline teleosts: tilapia, killifish, and mudsucker. This immunofluorescence was eliminated by incubating the primary antibody with excess somatostatin or somatostatin-28 but not with urotensin II, a partial analogue of somatostatin. In all three fishes, the strongest reaction was seen in the proximal pars distalis and parts of the pars intermedia. Strongly fluorescing processes from cells of the preoptic nucleus extend toward the pituitary. Distinct fluorescence was also associated with the neurohypophysis penetrating into the rostral pars distalis in the tilapia but not in the killifish or mudsucker. In the tilapia, an extensive network of immunofluorescent fibers and small cells were present in the anterior dorsolateral telencephalon, in addition to a moderately fluorescing group of cells anterolateral to the preoptic nucleus. A small area of diffuse fluorescence was also seen in the anterior dorsolateral midbrain tegmentum. Previous physiological studies have implicated somatostatin as a regulator of prolactin cell activity in tilapia. The present study demonstrates the route by which somatostatin may be delivered to the rostral pars distalis to inhibit prolactin secretion.

Animals↗
PubMed1985

Isolation and partial characterization of a pair of prolactins released in vitro by the pituitary of a cichlid fish, Oreochromis mossambicus.

The pituitary of the cichlid fish tilapia secretes two prolactins (PRLs) of molecular masses 20 kDa and 24 kDa. The 20-kDa PRL has an isoelectric point in the range of those of mammalian PRLs (pI 6.7), but the 24-kDa PRL is unusually basic (pI 8.7). Partial sequence information indicates that the PRLs are homologous but distinct proteins, differing by five amino acids within the first 29 NH2-terminal residues. Homology in the known region is higher with chum salmon PRL than with known mammalian PRLs. Reversed-phase HPLC permits isolation of these two PRLs and a single tilapia growth hormone from culture medium or from the pituitary in a single step. HPLC and radio-HPLC analysis of [3H]leucine pulse-chase experiments reveal that each PRL is secreted in vitro at remarkably high rates (21 pmol per gland per hr) and that the two PRLs are released in approximately equimolar amounts, suggesting the coordinate regulation of the secretion. Both PRLs exert characteristic PRL activity in that they prevent the loss of Na+ from the plasma of hypophysectomized tilapia in fresh water.

Amino Acid Sequence↗
PubMed1985

Prolonged vaginal cornification and other changes in mice treated neonatally with coumestrol, a plant estrogen.

This study used the neonatal mouse model to determine if early exposure of female mice to coumestrol, a plant estrogen, would result in reproductive-tract alterations similar to those seen after neonatal exposure to diethylstilbestrol (DES). Newborn female C57BL/Crgl mice were given daily subcutaneous injections of 0.08 micrograms DES or 100 micrograms coumestrol in 0.005 ml dimethyl sulfoxide (DMSO), or DMSO alone, or were untreated, for the first 5 d of life. The doses chosen were equivalent in biological activity based on published uterine bioassay data (using young adult mice). Observations were made twice daily for 1.5 mo to determine the times of eye and complete vaginal opening. Half of the animals were ovariectomized at 40 d of age. Vaginal lavages were examined for 30 consecutive d beginning both at 2 and at 5 mo of age. DES and coumestrol significantly advanced the time of complete vaginal opening and induced a comparable degree of ovary-independent persistent vaginal cornification. In addition, coumestrol resulted in the occurrence of hemorrhagic ovarian follicles.

Animals↗
PubMed1985

Long-term responses of the mouse uterus to neonatal diethylstilbestrol treatment and to later sex hormone exposure.

The effects of ovariectomy at 1 month of age and continuous 17 beta-estradiol (E2) and/or progesterone (P) replacement on the uterus of BALB/cCrgl mice neonatally treated with diethylstilbestrol [(DES) CAS: 56-53-1; alpha-alpha'-diethyl-4,4'-stilbenediol] or sesame oil were recorded after 1, 4, 7, and 10 months of treatment. DES-exposed uteri were found to be hypoplastic, less responsive to the growth-promoting effects of E2, and more likely to develop smooth muscle abnormalities after continuous hormonal treatment than similarly treated control uteri. Neonatal DES treatment led to leukocytic infiltration, disruption in the organization of the inner circular smooth muscle layer, and development of a population of epithelial cells believed to respond to later E2 treatment by proliferation and stratification (squamous metaplasia). Qualitative and quantitative responses to continuous P treatment and the development of cystic glandular hyperplasia and adenomyosis were found to be unaltered by neonatal DES administration. The relevance of these results to the problems of uterine abnormalities observed in women exposed to DES in utero is discussed.

Age Factors↗
PubMed1985

Induction of abnormal epithelial changes by estrogen in neonatal mouse vaginal transplants.

Adenosis occurred in transplanted C57BL and BALB/c mice Müllerian-derived reproductive tract regions, cervix, and/or fornix (FX), and middle vagina but never in the urogenital sinus-derived portion of the vagina, after a 1-mo exposure to endogenous ovarian hormones or exogenous estradiol (E2). Grafts in ovariectomized hosts did not exhibit adenosis, confirming its dependence on estrogen. C57BL FX and midvaginal transplants from 1-, 3-, and 5-day-old donors but not from 7- or 10-day-old donors developed adenosis, indicating a critical period before day 6. Prolonged E2 exposure (to 2 mo) decreased the adenosis incidence observed in the C57BL FX group but not in midvaginal transplants. Progesterone added during the second half of transplantation to continuing exogenous E2 prevented this reduction in the FX group; however, adenosis incidence in the similarly treated middle vagina group was less than that observed after 1 or 2 mo of E2 treatment alone. Progesterone present throughout the 2-mo transplantation period did not significantly affect adenosis incidence induced by 2-mo exposure of midvaginal or FX grafts to E2 alone. Changes suggestive of squamous cell carcinoma were found in a few BALB/c midvaginal grafts after E2 exposure for 1 mo and in some C57BL midvaginal and FX grafts after E2 and progesterone exposure for 2 mo.

Animals↗
PubMed1984

Cervicovaginal abnormalities in BALB/c mice treated neonatally with sex hormones.

Newborn female BALB/cCrgl mice received hormone treatments (daily for 5 days): 10(-1) micrograms diethylstilbestrol (DES), 2 X 10(-1) micrograms DES, 2 micrograms DES, 100 micrograms progesterone (P), 137 micrograms 17 alpha-hydroxyprogesterone caproate, 10(-1) micrograms DES + 100 micrograms P, 2 micrograms DES + 100 micrograms P, 5 micrograms testosterone (T), 20 micrograms T, 20 micrograms 5 alpha-dihydrotestosterone (DHT), or sesame oil and were examined at 25 days, 35 days, or from 10 to 30 days of age. Three major cervicovaginal abnormalities were noted: adenosis (heterotopic columnar epithelium) in the fornices; altered common cervical canal (aberrantly simplified cervical lumen), and twin fornix (lateral branching of either or both fornices). Only DES, administered alone or in conjunction with P, resulted in adenosis and altered common cervical canal. At 25 days, all mice given 2 X 10(-1) micrograms DES showed adenosis. At 35 days, 75% of mice given 10(-1) micrograms or 2 micrograms DES showed adenosis. Adenosis incidence following 10(-1) micrograms DES was decreased by concomitant P. Altered common cervical canal was present in more than 90% of mice treated with DES alone at both 25 and 35 days; concomitant P lowered the incidence in mice receiving 10(-1) micrograms DES. Neonatal exposure to endogenous prolactin from a pituitary transplant did not modify the response. Twin fornix was not evident 10 days after neonatal androgen treatment. The frequency increased significantly by day 15 of treatment, reaching 100% by day 20; incidence then declined to 86% and 63% on days 25 and 30 after treatment, respectively. Thus, neonatal sex hormone administration results in various cervicovaginal changes, some transient, decreasing with age in young mice.

Abnormalities, Drug-Induced↗