Biomedical subjects

D L Greenman

Publications and source records attributed to D L Greenman.

At least 37 records · Page 2Linked to original sources

PubMed1986

Influence of age on induction of mammary tumors by diethylstilbestrol in C3H/HeN mice with low murine mammary tumor virus titer.

C3H/HeN female mice with low murine mammary tumor virus titer (MTV-) were fed diets containing a targeted concentration of 640 ppb diethylstilbestrol [(DES) CAS: 56-53-1; 4,4'-(1,2-diethyl-1,2-ethenediyl)bis-phenol]. Mice were started on DES at 3, 5, 7, or 9 weeks of age. Some continued on the diet throughout the rest of their life-spans, whereas others were killed as soon as they had been fed DES for 2, 4, 6, 8, 10, or 12 weeks. Controls were also examined throughout the study. Among mice killed early, the only observation significantly influenced by age at the start of DES treatment was the presence or absence of corpora lutea (CL). DES did not prevent CL from appearing in mice started on DES at 7 or 9 weeks of age, but it did prevent their appearance in about 25% of the mice started at 5 weeks and in up to 75% of the mice started at 3 weeks of age. In the life-span-exposure groups, CL either disappeared or were never formed in 88% or more of the mice, regardless of age at the start of treatment. Neoplastic or presumptive preneoplastic lesions apparently influenced by DES in the life-span-treatment groups included ovarian tubular adenomas; granulosa cell tumors and luteomas; pituitary cystoid degeneration, hyperplasia, and adenomas; uterine adenocarcinomas and cervical adenosis; mesotheliomas; and mammary hyperplastic alveolar nodules (HANs) and adenocarcinomas. Luteoma and granulosa cell tumor incidences were reduced by DES, regardless of age at the start of treatment. Influence of age at the start of treatment was minimal or not apparent for mesotheliomas, uterine adenocarcinomas, or pituitary adenomas; however, pituitary cystoid degeneration and hyperplasia and cervical adenosis occurred in higher frequency and/or with shorter duration of DES exposure the earlier that treatment was started. A delay in the start of DES treatment was associated with a remarkable delay in HAN and mammary adenocarcinoma development. This was especially apparent in young mice (3-7 wk old) in which a 2-week delay in treatment resulted in a 20-week delay in HAN or tumor onset. Age at the start of treatment was a major factor in susceptibility of C3H/HeN-MTV- female mice to DES-induced mammary tumorigenesis.

Adenocarcinoma↗

PubMed1986

Sex specificity of myocardial damage in mice fed a purified diet.

Both sexes of BALB/c and B6C3F1 mice were divided into test groups and fed either a purified diet (AIN-76A) or a natural ingredient diet (NIH-07) containing graded levels of 2-acetylaminofluorine (2-AAF) for 90 days. A large number of dead or moribund B6C3F1 males fed the AIN diet were removed from the study prematurely. AIN-fed B6C3F1 mice removed early as well as some sacrificed at the end of the study showed myocardial damage with hemorrhage. A much smaller number of BALB/c males fed the AIN diet also exhibited these signs while none of the females from either stock were affected. Mice having these lesions were confined largely to 2 of 5 treatment groups. Increased levels of serum aspartate aminotransferase (GOT) (P less than .01) occurred in the AIN-fed B6C3F1 male mice that were sacrificed, supporting the histopathological observation of myocardial damage. There was no other significant difference in the GOT between diets or 2-AAF doses. No environmental factors could be associated with the problem and microbiological and chemical analyses of the diets showed no convincing evidence of specific pathogenic organisms or nutritional deficiencies that might have caused these lesions. Extended storage (up to 4 months) and one batch of feed in particular seemed to be associated with mice having myocardial damage. These associations were highly strain and sex dependent and suggest that great care must be taken in the manufacture and handling of the diet. Furthermore, it seems likely that the diet may be marginally adequate for some strains of mice and may require modification before it will become generally useful.

Animals↗

PubMed1985

Influence of age and environment on the induction of mammary tumours by diethylstilboestrol in C3H/HeN-MTV+ mice.

C3H/HeN-MTV+ female mice were fed diets containing targeted concentrations of 320 or 640 ppb diethylstilboestrol (DES) starting at 3, 5, 7 or 11 wk of age and continuing throughout their remaining lifespan. Mice were housed in either a single-corridor conventional animal room or in a double-corridor barrier-type animal room. Mice housed in the conventional animal room and started on DES at 7 or 11 week of age developed palpable mammary tumours somewhat sooner than the corresponding groups of mice kept in the barrier animal room. In mice housed in the barrier animal room and exposed to a given DES concentration, there was very little difference between mice started on DES at 3, 5 or 7 wk of age in the exposure time required for the development of palpable mammary tumours. There was a striking difference, however, between mice started on DES at 7 wk and those started at 11 wk of age in the exposure time needed before mammary tumours appeared. Mice started at 11 wk of age developed tumours with, on average, about 4 wk less exposure than did those started at 7 wk. This suggests that treatment between 7 and 11 wk of age had little or no effect on mammary tumour development. In conclusion, both animal-room environment and age at the start of DES treatment influenced the mammary tumour response in female C3H/HeN-MTV+ mice.

Adenocarcinoma↗

PubMed1985

Occurrence of tumors among litters of BALB/c female mice.

In the application of statistical techniques to tumor incidence data it is generally assumed that animals respond independently with regard to tumor occurrence, with littermates being no more alike than are animals from different litters. Data for nine different types of tumors from the large ED01 study conducted at the National Center for Toxicological Research were used to compare tumor prevalence rates among litters with the tumor rates expected under the assumption of homogeneity of tumor rates among litters. These data did not provide sufficient evidence to reject the assumption of homogeneity of tumor prevalence rates among litters of inbred female BALB/c mice for either spontaneously occurring tumors or bladder tumors produced by exposure to 2-acetylaminofluorene (CAS: 53-96-3). However, there does appear to be a difference in liver tumor prevalence rates among litters at 24 months of age. Thus litter effects are a factor that should be considered in the assignment of animals to treatment groups in carcinogenesis studies.

2-Acetylaminofluorene↗

PubMed1985

Quality changes in animal feed resulting from extended storage.

The objective of this study was to determine if extended storage of animal feed after autoclaving had an effect on the quality of feed which could be deleterious to experimental animals. Fresh animal feed was autoclaved each week and placed in an environmentally controlled storage room (18.5 +/- 2 degrees C with 50 +/- 5% RH). This process provided feed on a weekly basis that had a consistent storage time of 10, 74 or 130 days. Weanling male and female BALB/c and B6C3F1 mice were the test animals. The animals were housed four to a cage and were started on the experiment in two replicates separated by one week. The study was terminated after 13 weeks. Food consumption and body weights were measured weekly and serum protein levels analyzed upon termination of the study. Statistical analysis of the results showed several interactions among gender, replication and mouse genome, but no significant differences were present among treatment groups for the serum proteins or weight ratios. The animals appeared to be normal, and a histological examination of the liver showed no signs of disease or nutritional disorders. This study indicates that feed can be stored up to 130 days after autoclaving without apparent deleterious effects on animals receiving the feed.

Animal Feed↗

PubMed1984

Histochemical and ultrastructural characteristics of the endometrial connective tissue stroma from mice continuously fed diethylstilbestrol.

Histochemical and transmission electron microscopy were utilized to examine the endometrial connective tissue stroma of mice continuously fed diethylstilbestrol (DES). Virgin female mice were continuously fed diets containing 0, 320, or 640 ppb DES from 4 weeks of age until moribund. All animals reported on in this study were between 622 to 762 days of age when sacrificed. Light microscopy revealed irregular deposits of homogeneous acidophilic material throughout the connective tissue stroma with frequent accumulations seen immediately beneath the surface epithelial layer and surrounding blood vessels. Histochemical results indicated the presence of collagen and fibrin as components of the acidophilic material. Ultrastructural results revealed a homogeneous stroma consisting of short segments of collagen fibrils enmeshed in an amorphous component. Numerous plasma cells were seen in close approximation to macrophages and lymphocytes. Fibroblast cell membranes exhibited micropinocytotic vesicles. Eosinophils were numerous in the stroma and often seen in close approximation to fibroblast projections. Vascular endothelial layers contained numerous micropinocytotic vesicles and marginal flaps. The accumulation of homogeneous material within the connective tissue stroma may represent products from collagen degradation and a subsequent localized immune response as well as plasma components.

Animals↗

PubMed1984

Influence of strain and age on the induction of mammary tumours by diethylstilboestrol in C3H mice.

C3H/HeJ and C3H/HeN female mice were fed diets containing targeted concentrations of 320 or 640 ppb diethylstilboestrol (DES) starting at 7 or 11 wk of age and continuing throughout their remaining lifespan. Regardless of the DES concentration there was a faster rate of development and higher final incidence of mammary adenocarcinomas among the C3H/HeN mice than among the C3H/HeJ mice. In C3H/HeN mice started on DES when 11 wk old, mammary tumours developed more rapidly than when treatment was started at 7 wk of age. This was also true for C3H/HeJ mice given 320 ppb DES but not for those treated with 640 ppb DES. Both age at the start of treatment and strain of C3H mice are important factors to be considered in designing experiments to study the tumorigenic activity of oestrogens such as DES.

Adenocarcinoma↗

PubMed1984

Neoplastic and nonneoplastic responses to chronic feeding of diethylstilbestrol in C3H mice.

Over 3000 female C3H/Hen-MTV+ mice continuously received graded dietary levels (0, 2.5, 5, 10, 20, 40, 80, 160, 320, and 640 ppb) of diethylstilbestrol (DES) beginning at weaning. Mice were scheduled to be killed after 3 or 26 wk of exposure and were palpated weekly and removed for histological evaluation when subcutaneous masses reached 1 cm diameter. Mammary tumors were more prevalent than in controls only at 320 and 640 ppb DES. However, palpable mammary tumors appeared significantly earlier than in controls in mice fed 80 ppb and above. Mice killed at 3 wk and later showed a dose-response for several nonneoplastic endpoints. At 3 wk, moderate to severe uterine glandular hyperplasia, lack of corpora lutea, and vaginal keratinization were more prevalent than in controls at 80 ppb; cervical adenosis was more prevalent than in controls at 160 ppb and above. Generally, the prevalence of other nonneoplastic responses such as uterine fibrosis, stromal mucoid changes, and bony trabecular proliferation were increased above control levels only later than 3 wk at 160 ppb and greater. This study demonstrated neoplastic and nonneoplastic responses to DES at and above 80 ppb, but gave no clear evidence of either type of response below this level. Conclusions are, (1) dietary levels of DES causing nonneoplastic effects also cause neoplastic effects when fed chronically, and (2) neoplastic levels of DES may be predicted from a 3 wk feeding study in C3H/HeN-MTV+ female mice based on nonneoplastic responses.

Animals↗

PubMed1984

Association between cage shelf level and spontaneous and induced neoplasms in mice.

Data from a chronic feeding study with 2-acetylaminofluorene [(2-AAF) CAS: 53-96-3; N-fluoren-2-yl-acetamide] done on 20,880 female BALB/c mice were analyzed for associations between cage shelf level and occurrence of induced and spontaneous neoplasms. Each cage was maintained on a rack at a given shelf level throughout the experiment, allowing analysis of data by shelf level. Differences in the crude incidence of 2-AAF-induced liver and bladder neoplasms appeared to be shelf related, but these differences were small and disappeared when shelf-level analyses of time-to-tumor onset distributions were performed. There was evidence for a shelf-level influence on 5 of the 6 major spontaneous neoplasms noted. Time to onset of uterine polyps and reticulum cell sarcomas was significantly delayed on the top shelf of five of six animal rooms. Also, there was a significant delay in onset of lymphomas, adrenocortical adenomas, and lung alveolar cell tumors on the top shelf when data were combined from all six animal rooms, but these delays on the top shelf were significant in no more than two of six animal rooms when rooms were analyzed separately. There was no indication of any shelf-level influence on the development of harderian gland adenomas. In conclusion, shelf level is an environmental factor that should be considered in the design and analysis of carcinogenesis studies.

2-Acetylaminofluorene↗

PubMed1983

Relationship of mouse body weight and food consumption/wastage to cage shelf level.

The relationships between the shelf level at which mice were housed and body weight and food consumption/wastage were examined by analyzing data obtained from the first 9 months of a carcinogenic dose-response study carried out in 24,192 female BALB/c mice using 2-acetylaminofluorene (2-AAF) as the carcinogen. Each cage, containing four mice, was maintained on a rack at a given shelf level throughout the course of the experiment to allow analysis of data by shelf level. The amount of food removed from each feeder and the body weight of each mouse was measured weekly. Average body weight gain during the first 12 weeks was lowest on the top shelf, highest on the next two shelves, and progressively lower as the shelf approached the lowest level on the rack. Body weights attained by week 36 of the experiment generally reflected this same pattern. Weekly food consumption/wastage, as measured by disappearance of food from the feeder, generally showed the converse shelf-level pattern as that shown by body weight gain. Removal of food from feeders was greatest on the top shelf, lowest on the next shelf, and progressively increased with each succeedingly lower shelf. Although it is not clear whether the food removal pattern was related more to food consumption or food wastage, the observation was reproducible.

2-Acetylaminofluorene↗

PubMed1982

Correlation of urothelial morphologic characteristics with the development of bladder carcinomas in BALB/c female mice administered 2-acetylaminofluorene.

Urinary bladders from 6909 of 24,172 control or 2-acetylaminofluorene (2-AAF) treated female BALB/c mice were examined histopathologically. Dietary doses of 2-AAF ranged from 75 to 150 p.p.m. for up to 33 months. Urinary bladder epithelial hyperplasia, vacuolization, and inflammation were frequent observations in treated animals and showed a positive correlation with dose level and length of administration of 2-AAF. Concretions were infrequently found and occurred only in controls. Squamous metaplasia, ulceration, and lymphocytic accumulations were infrequently noted but gave some indication of a positive correlation with 2-AAF dose level. Vacuolization was always associated with hyperplasia and/or bladder tumors. Observations on the concurrence of hyperplasia, vacuolization, and neoplasia suggest that both hyperplasia and vacuolization may be precursors of neoplasia. While inflammation was infrequently noted in non-tumor-bearing animals, greater than 90% of the time it was seen in association with tumors and appears to be a response of the bladder to tumor progression.

2-Acetylaminofluorene↗

PubMed1982

Effects of storage conditions on nutritional qualities of semipurified (AIN-76) and natural ingredient (NIH-07)diets.

The effects of storage condition on the shelf life of the AIN-76 diet were investigated. Samples of the diet were stored at -70 degrees, 4 degrees, 20 degrees, and 23-30 degrees under atmospheric air and at 4 degrees and 20 degrees under argon. Levels of vitamin A, thiamine, rancidity, bacteria and mold were monitored during 168 days of storage. A 41.3% loss of vitamin A occurred in samples stored at 23-30 degrees. A marked decline in thiamine was observed in all samples stored at 20 degrees or above. Loss of thiamine was significantly greater in samples stored at 20 degrees than in those stored at 4 degrees, and greater in samples stored under air than those stored under argon. Rancidity reached a level previously shown to be associated with a disagreeable odor and taste (peroxide value greater than 140) with in 30, 50 and 90 days when the diet was stored at 23-30 degrees or 20 degrees under air and 20 degrees under argon, respectively. Peroxide values remained well below 140 in samples stored at 4 degrees or colder. None of the nutritional parameters tested reached unacceptable levels in any of the samples stored at 4 degrees or colder during the 168 days. These results indicate that to achieve maximum shelf life, the AIN-76 diet should be stored at 4 degrees or colder. Although less effective than low temperature, an argon atmosphere extended the shelf life and was additive with lower temperatures.

Air↗

PubMed1982

Influence of cage shelf level on retinal atrophy in mice.

The correlation between cage shelf level and retinal atrophy was examined by analyzing data obtained from a chronic study carried out in 24,192 female BALB/c mice. Each cage of animals was maintained on a cage rack at a given shelf level throughout the course of the experiment, thus allowing analysis of data by shelf level. Retinal atrophy was first observed in a mouse killed at 12 months but subsequently was observed only at and after 16 months. This lesion was confined largely to animals on the top shelf. At 24 months, 19.7% of the mice on the top shelf had retinal atrophy while 0.2% of animals on all other shelves had the lesion. By 33 months, retinal atrophy was present in 30.2% of the mice on the top shelf, 12.0% on the next shelf, and 0.7% on the lower shelves. Differences in retinal morphology were probably caused by differences in lighting intensity. It was concluded that cage shelf level should be considered as an important factor in any chronic studies with mice.

Animals↗

PubMed1981

Osseous changes and osteosacomas in mice continuously fed diets containing diethylstilbestrol or 17 beta-estradiol.

In a study on the long-term effects of dietary diethylstilbestrol or 17 beta-estradiol on C3H mice, estrogens induced a proliferation of osseous trabeculae and increased the incidence and hastened the development of osteofibrotic areas in the sterna. There were 6 osteosarcomas, 2 having metastases, in 1,242 mice fed dietary estrogens over 360 days, but none in 356 untreated controls. These tumors were reviewed along with 4 early sternal osteosarcomas selected from 17 osteosarcomas (only 1 in a control) found thus in two other ongoing comparable studies. In at least 1 case, and possibly in 2 other early cases, tumors were associated with areas of osteofibrosis, and 1 tumor was probably associated with proliferation of bony trabeculae in the medullary cavity.

Animals↗

PubMed1980

Commercial laboratory animal diets: toxicant and nutrient variability.

A commercial rodent feed was analyzed for a series of nutrients and potential contaminants during a 5-yr period. Annual average Cu and vitamin A concentrations were generally at least 12% lower than the approximate concentrations listed by the manufacturer, whereas Ca, protein, and vitamin B1 were within +/- 5% and fat and Zn within +/- 8% of the manufacturer's specifications. Frequently, Se was found at concentrations at which it has been shown to interact with the process of chemical carcinogenesis. DDT, dieldrin, Cd, and Pb were occasionally close to concentrations known to have biological effects.

Animal Feed↗

PubMed1980

Correlations between gross and microscopic lesions in carcinogenic studies in mice.

Microscopic diagnoses of a number of spontaneous and induced neoplasms in mice were correlated with the gross findings of the ED01 and a number of other carcinogenic studies conducted at NCTR to determine the value of detailed histopathologic examinations in bioassay testing. The results indicated that for organs such as thymus, lung, adrenal, Harderian gland and urinary bladder 50% or more of the neoplastic lesions would be missed if at least one histological section were not examined from each organ. For organs such as the liver and mammary gland, a single tissue section did not greatly improve the ability to detect neoplastic lesions beyond that afforded by a thorough necropsy examination.

Adrenal Cortex Neoplasms↗

PubMed1980

Neoplastic and preneoplastic lesions induced in female C3H mice by diets containing diethylstilbestrol or 17 beta-estradiol.

To study the long term effects of estrogenic diets, 2160 virgin female C3H/Hel mice, having a high titer to the mammary tumor virus factor (MMTV), were fed diets containing 0, 10, 100, 500, or 1000 ppb diethylstilbestrol (DES) or 100, 1000, or 5000 ppb 17 beta-estradiol (E2) from 6 to 110 weeks of age; 1368 virgin female C3HeB/FeJ mice, having a low titer to the MMTV, were fed diets containing 0, 10, 1000, or 500 ppb DES from 6 to 136 weeks. In estrogen-treated mice, the incidence of cervical adenosis and of mammary hyperplastic alveolar nodules was increased and the time to development of mammary adenocarcinomas was shortened. These changes tended to increase with dose and time and appeared earlier in the C3H/HeJ mice. Other tumors observed included 32 cervical and 20 endometrial adenocarcinomas, 16 cervical granular cell myoblastomas, 12 peritoneal mesotheliomas involving the uterus, 2 cervical and 4 vaginal squamous cell carcinomas, 2 ovarian teratomas, 6 osteosarcomas, 25 pheochromocytomas and 3 thyroid carcinomas. Of these tumors, 1 cervical and 2 endometrial adenocarcinomas, and 4 pheochromocytomas occurred in C3HeB/FeJ control mice at 104-130 weeks; none occurred in C3H/HeJ controls. This study indicates that the MMTV facilitates the development of mammary lesions in C3H mice, that estrogens predispose C3H mice to endometrial and cervical adenocarcinomas, and that cervical adenosis may be a precursor of cervical adenocarcinoma in C3H mice and serve as an early indicator of the potential uterine carcinogenicity of a test compound. It supports the view that the C3H mouse may serve as an animal model for uterine adenocarcinomas and adenosis in women exposed to estrogens.

Animals↗

PubMed1980

Biologic and morphologic characteristics of urinary bladder neoplasms induced in BALB/c female mice with 2-acetylaminofluorene.

2-Acetylaminofluorene (2-AAF) induced transitional cell carcinomas, transitional cell carcinomas with squamous metaplasia, squamous cell carcinomas and undifferentiated carcinomas in the urinary bladders of BALB/c female mice. The transitional cell carcinoma was the most common, but was less aggressive and infiltrative than the other three types. The carcinomas were most likely to occur in the vertex of the bladder. A positive correlation existed between dose and length of administration of 2-AAF and the incidence, type, depth of invasion, and the location of the bladder carcinoma.

2-Acetylaminofluorene↗