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PubMed2003

Dietary cadmium inhibits spontaneous hepatocarcinogenesis in C3H/HeN mice and hepatitis in A/J mice, but not in C57BL/6 mice.

Cadmium is known to be a potent carcinogenic and mutagenic metal. However, we demonstrated that dietary supplementation with 50 ppm cadmium inhibits spontaneous carcinogenesis in C3H/HeN and spontaneous hepatitis in A/J mice. We found that the frequencies of spontaneous hepatocarcinogenesis in C3H/HeN mice and of spontaneous hepatitis in A/J mice fed low-dose cadmium for 54 weeks were significantly lower than those in the respective control groups. A cadmium-induced increase in metallothionein production itself and/or metallothionein-associated increases in hepatic zinc concentrations may be involved in the observed preventive effects of cadmium. Our results suggest that low doses of cadmium in the diet or environment may play a beneficial role in the prevention of hepatic disease in humans and animals.

Animals↗
PubMed1998

Pathogenesis of pneumovirus infections in mice: detection of pneumonia virus of mice and human respiratory syncytial virus mRNA in lungs of infected mice by in situ hybridization.

The pathogenesis of pneumonia virus of mice (PVM) and human respiratory syncytial virus (HRSV) in BALB/c mice were investigated by using in situ hybridization to detect virus mRNA in fixed lung sections. Following intranasal inoculation with 120 p.f.u. PVM the pattern of hybridization showed that virus mRNA was initially detected within 2 days in alveolar cells. As the infection progressed the number of hybridizing alveolar cells increased and signal was also detected in cells lining the terminal bronchioles. By days 4 to 5 post-infection areas of morphological abnormality could be seen, particularly in the strongly hybridizing regions of the lung, and this correlated with the appearance of clinical signs of infection. In animals which survived the infection virus-specific mRNA could not be detected 10 days post-infection. Mice infected with 1500 p.f.u. HRSV showed significant differences in the distribution of virus-specific mRNA when compared to the pattern seen with PVM. HRSV mRNA was detected over large areas, but predominantly in peribronchiolar and perivascular regions of the lungs 5 days post-infection. The yield of PVM from infected mouse lungs was considerably higher than that of HRSV. The possible implications of these results for the use of the mouse model for pneumovirus infections are discussed.

Animals↗
PubMed2003

Folate and vitamin E deficiency impair cognitive performance in mice subjected to oxidative stress: differential impact on normal mice and mice lacking apolipoprotein E.

One factor contributing to the age-related decline in cognitive performance is increased oxidative stress, that can arise from environmental, nutritional, and/or genetic compromise. Folate deficiency has been linked to several age-related neurodegenerative conditions, including Alzheimer's disease (AD), at least in part by increasing oxidative stress. Folate deficiency also potentiates the impact of other known risk factors for AD. Adecrease in function of apolipoprotein E (ApoE), is associated with increased oxidative stress and is a risk factor for AD. We tested the combined impact of dietary deficiencies in folate and vitamin E, coupled with exposure to high dietary iron as a pro-oxidant, on cognitive performance in normal and ApoE-/- mice by monitoring the percent alternation in passive Y and T maze tests. Both normal and ApoE-/- mice displayed some cognitive impairment when deprived of folate and vitamin E and exposed to iron, but ApoE-/- mice were more severely affected. These findings highlight the potential combined impact of dietary deficiencies and genetic predisposition to neurodegeneration. They further leave open the possibility that one or more risk factors may remain latent, and neurodegeneration may ensue only following augmentation by one or more additional traumatic events or conditions.

Aging↗
PubMed1996

Determination of hemoglobin A1C in normal and diabetic mice: neonatal streptozotocin-induced diabetic mice and KK-Ay mice.

We have determined Hemoglobin A1C (HbA1C) in normal, neonatal streptozotocin-induced diabetic animals (NSZ), a model of lean-type non-insulin-dependent diabetes mellitus (NIDDM) with hypoinsulinaemia, and KK-Ay mice, a model of obese-type NIDDM with hyperinsulinaemia. The HbA1C of NSZ mice was slightly increased from 5 to 20 weeks while the HbA1C of KK-Ay mice was markedly increased from 5 to 10 weeks. Our findings showed a difference between experimentally-induced (NSZ) and genetically (KK-Ay) diabetic animals.

Animals↗
PubMed1986

Autoradiographic studies with 3H dihydrotestosterone in the brain of sex reversed mice, heterozygous for androgen insensitive testicular feminization (Tfm). A comparison with normal female mice and sex reversed male mice.

Specific binding sites for 3H dihydrotestosterone are demonstrated by autoradiography in brain nuclei of sex reversed mice heterozygous for testicular feminization (Tfm) which are phenotypically intersexes with testes and accessory sex glands that consist of a mosaic of androgen insensitive Tfm cells which lack specific dihydrotestosterone binding and androgen sensitive normal cells. The nuclear group evaluated include: nucleus (n.) septi lateralis, n. interstitialis striae terminalis, n. medialis amygdalae, the hypothalamic n. arcuatus, n. ventromedialis lateralis, n. pre-mammillaris ventralis, n. preopticus medialis, and nuclei of the cranial nerves VII, X, and XII. In the sex reversed males and the female, used as controls, the frequency of neurons with specific DHT binding show a distinct male-female difference in the caudal part of the arcuate nucleus. In the sex reversed Tfm heterozygotes, in all brain nuclei studied, the frequency of labeled neurons is reduced. The extent of reduction of androgen binding in the different brain nuclei varies among as well as within individual sex reversed Tfm heterozygotes, suggesting variations of the ratio of normal to Tfm neurons in sex reversed Tfm heterozygotes. The differentially reduced androgen binding of different brain systems corresponds to a differentially reduced androgen dependent behaviour reported in the literature.

Amygdala↗
PubMed1977

Immunologic tolerance to HGG in mice. I. Suppression of the HGG response in normal mice with spleen cells or a spleen cell lysate from tolerant mice.

Adoptive transfer of spleen cells or spleen cell lysates from mice tolerant to human-gamma-globulin (HGG) specifically suppressed the response of normal syngeneic recipients to HGG. The suppressive activity could be transferred for over 100 days after tolerance induction. The suppression induced by both spleen cells and spleen cell lysate was found to be specific as evidenced by a normal response to a challenge with turkey-gamma-globulin or goat erythrocytes. The activity of the suppressive lysate could be removed by passing the material through an HGG immunoadsorbent column but not by passing it through an anti-HGG column or a BSA column. These results indicated that the factor had antigen specificity and was probably not antigen-antibody complexes. That this suppression was not due to a shifting of the kinetics of the antibody response has also been demonstrated. The antigen-specific suppressor factor in the tolerant spleen cell lysates was a protein with a m.w. of approximately 45,000 daltons. The kinetics of the appearance of both suppressor cells and suppressor factor were consistent with a mechanism of active suppression functioning in the maintenance of tolerance to HGG.

Animals↗
PubMed1997

Thyroid xenografts from patients with Graves' disease in severe combined immunodeficient mice and NIH-beige-nude-xid mice.

OBJECTIVE: To compare human thyroid xenografts from patients with Graves' disease in severe combined immunodeficient (SCID) mice and triple immunodeficient NIH-beige-nude-xid (NIH-3) mice to obtain an improved animal model for studying these xenografts. DESIGN: Animal study. PARTICIPANTS AND ANIMALS: Patients with Graves' disease; SCID and NIH-3 mice. INTERVENTIONS: Thyroid tissue from six patients with Graves' disease was xenografted to SCID and NIH-3 mice; in addition, peripheral blood mononuclear cells (PBMC) from 12 patients with Graves' disease were grafted intraperitoneally to separate SCID and NIH-3 mice. OUTCOME MEASURES: Levels of human immunoglobulin (IgG), thyroperoxidase antibodies (TPO-Ab), thyroglobulin (Tg-Ab), and expression of thyrocyte intercellular adhesion molecule-1 (ICAM-1) and histocompatibility leukocyte antigen (HLA-DR) in mice after xenografting. RESULTS: IgG was detected in all mice grafted with Graves' thyroid tissue and some mice grafted with PBMC; levels of human IgG peaked 6 to 10 weeks after xenografting. Human IgG levels reached a mean of 500 mg/L (standard error of the mean [SEM] 150 mg/L) in the NIH-3 mice with thyroid xenografts. This was similar to results in SCID mice with thyroid xenografts, which had a mean level of human IgG of 640 mg/L (SEM 230 mg/L). PBMC xenografting resulted in a mean IgG level of 1200 mg/L (SEM 250 mg/L) in NIH-3 mice, which was similar to the mean level of 1000 mg/L (SEM 280 mg/L) in SCID mice. The rate of rise in human IgG in the sera of the NIH-3 mice with thyroid xenografts was similar to that in the SCID mice. TPO-Ab were also detected in some mice with Graves' thyroid grafts and in a few mice injected with PBMC, with levels peaking 4 to 6 weeks after xenografting. TPO-Ab levels reached a mean 109.3 U/mL (SEM 57.2 U/mL) in the NIH mice with thyroid xenografts, which were similar to the mean level of 91.7 U/mL (SEM 34.2 U/mL) in the SCID mice. There were no significant differences in the Tg-Ab levels in each type of mice (13.9 [SEM 12.1] U/mL v. 17.9 [SEM 7.9] U/mL). Eight weeks after xenografting into mice, the expression of xenograft thyrocyte ICAM-1 decreased significantly in both the SCID and NIH-3 mice (from 43.4%, SEM 4.9%, to 35.9%, SEM 4.6%, in the NIH-3 mice, p < 0.05, and from 43.4%. SEM 4.9%, to 32.5%, SEM 5.2%, in the SCID mice, p < 0.05). However, the expression of thyrocyte HLA-DR did not change significantly in the NIH-3 mice (from 11.5%, SEM 3.3%, to 10.8%, SEM 3.3%), whereas it decreased significantly in the SCID mice (from 11.5%, SEM 3.3%, to 4.2%, SEM 2.0%, p < 0.02). CONCLUSIONS: Not only SCID mice but also NIH-3 mice may be useful as animal models for xenografted thyroid tissue, which will help us elucidate the pathogenesis of autoimmune thyroid disease. NIH-3 mice are superior to SCID mice in maintaining the expression of thyrocyte HLA-DR in Graves' thyroid xenografts at levels as high as those before xenografting; this maintenance of expression may be due to the lack of natural killer cells in NIH-3 mice.

Animals↗
PubMed1995

NTP Toxicology and Carcinogenesis Studies of Diethylphthalate (CAS No. 84-66-2) in F344/N Rats and B6C3F1 Mice (Dermal Studies) with Dermal Initiation/ Promotion Study of Diethylphthalate and Dimethylphthalate (CAS No. 131-11-3) in Male Swiss (CD-1(R)) Mice.

Diethylphthalate and dimethylphthalate are used as phthalate plasticizers, in an extensive array of products. The chronic dermal toxicity of diethylphthalate was evaluated in male and female F344/N rats and B6C3F1 mice in 2-year studies. In a series of special studies, the tumor initiation or promotion potential of diethylphthalate or dimethylphthalate was evaluated in male Swiss (CD-1(R)) mice by an initiation/promotion model of skin carcinogenesis. The genetic toxicity of diethylphthalate and dimethylphthalate in Salmonella typhimurium and cultured Chinese hamster ovary cells was also evaluated. 4-WEEK STUDY IN F344/N RATS: Groups of 10 male and 10 female rats were dermally administered diethylphthalate at volumes of 0, 37.5, 75, 150, or 300 &mgr;L (0, 46, 92, 184, or 369 &mgr;g) applied neat, 5 days per week for 4 weeks. All male and female rats survived to the end of the study. No evidence of dermatotoxicity was observed, with no adverse clinical signs observed and no effects on weight gain or feed consumption. Relative liver weights of 300 &mgr;L males and females and 150 &mgr;L females were greater than those of controls. Relative kidney weights of 150 and 300 &mgr;L males and 150 &mgr;L females were greater than those of controls. No other adverse effects were observed in this study. 4-WEEK STUDY IN B6C3F1 MICE: Groups of 10 male and 10 female mice were dermally administered diethylphthalate at volumes of 0, 12.5, 25, 50, or 100 &mgr;L (0, 15, 31, 62, or 123 &mgr;) applied neat, five days per week for 4 weeks. One control female died before the end of the study; all other mice survived. No evidence of dermatotoxicity or other adverse clinical signs were observed, and no clear adverse effects on weight gain or feed consumption were seen. Absolute and relative liver weights of 25 and 100 &mgr;L females were greater than those of the controls. Based on these 4-week study results, doses of 0, 35, and 100 &mgr;L diethylphthalate were recommended for the 2-year mouse studies. A chronic study in male and female B6C3F1 mice at 0, 35, and 100 &mgr;L (applied neat, once per day, 5 days per week) was started and subsequently stopped after 32 weeks when significant body weight reductions were noted in treated animals (males and females, 100 &mgr;L groups: 19% lower; males, 35 &mgr;L group: 12% lower; females, 35 &mgr;L group: 10% lower than controls). Based on these body weight reductions, doses of 0, 7.5, 15, and 30 &mgr;L in 100 &mgr;L acetone were recommended for the restart of the 2-year mouse study. 2-YEAR STUDY IN F344/N RATS: Based upon the results of the 4-week study, doses of 0, 100, or 300 &mgr;L diethylphthalate (0, 123, or 369 &mgr;) were chosen for the 2-year rat study. Groups of 60 male and 60 female rats received the doses applied neat 5 days per week for 103 weeks and up to 10 animals per group were evaluated after 15 months. Survival, Body Weights, and Clinical Findings: Survival of dosed rats during the first 15 months was similar to that of controls. However, 2-year survival was significantly reduced in all groups of male rats (survival probabilities, males: 0 &mgr;L, 8%; 100 &mgr;L, 12%; and 300 &mgr;L, 12%). The mean body weights of 300 &mgr;L males were slightly less than those of the controls throughout the study. No adverse clinical signs were observed, including no evidence of dermatotoxicity. Pathology Findings: No morphological evidence of dermal or systemic toxicity was observed in male or female rats. Skin neoplasms were not observed in female rats and were only rarely observed in male rats. A high incidence of anterior pituitary adenoma occurred in all groups of male and female rats. The incidence of anterior pituitary adenomas in the 0, 100, and 300 &mgr;L groups were: males, 39/44, 41/49, 41/49; females, 38/50, 33/49, 33/48. The incidence of this benign tumor in control males (84%) exceeded the historical control mean incidence [feed controls, (28.7%)] and range (12% to 60%). Anterior pituitary adenomas were considered a primary contributing factor in the increased mortality observed in all grtor in the increased mortality observed in all groups, regardless of treatment. A dose-related decreasing trend in the incidence of mammary gland fibroadenomas was observed in female rats (21/50, 12/48, 7/50). The incidence of mononuclear cell leukemia in male rats in this study was lower than the historical incidence and may be attributable to the shortened life span of male rats. Similarly, the incidence of interstitial cell tumors of the testes was markedly decreased in all groups of males (4/50, 3/50, 8/50), relative to historical control rates (90.1&percnt;; range 74&percnt;-98&percnt;). The incidence of fatty liver degeneration was notably lower in dosed rats than in controls (males: 26/50, 8/50, 4/51; females: 23/50, 11/50, 3/50). 2-YEAR STUDY IN B6C3F1 MICE: Groups of 60 male and 60 female mice received doses of 0, 7.5, 15, or 30 &mu;L diethylphthalate (0, 9, 18, or 37 &mu;) in 100 &mu;L acetone 5 days per week for 103 weeks with a 1 week recovery period, and up to 10 animals per group were evaluated after 15 months. Survival, Body Weights, and Clinical Findings: Two-year survival of dosed mice was similar to that of controls: 43/50, 41/48, 46/50, and 43/50 (males), and 41/50, 38/51, 37/49, and 36/49 (females). Mean body weights of dosed male and female mice were similar to those of the controls throughout the study. No adverse clinical signs were observed in mice, including no gross evidence of dermatotoxicity. Feed consumption by male and female mice was similar to or up to 13% greater than that by controls. Pathology Findings: No morphological evidence of dermal toxicity was observed in male or female mice. No skin neoplasms were observed in dosed male mice. In female mice receiving 30 &mu;L, one squamous cell carcinoma and one basal cell carcinoma were seen at the site of application. An increased incidence of liver neoplasms was observed in dosed male and female mice. The incidence of hepatocellular adenoma or carcinoma (combined) in B6C3F1 mice in the 0, 7.5, 15, and 30 &mu;L groups were: (males) 9/50, 14/50, 14/50, and 18/50; (females) 7/50, 16/51, 19/50, and 12/50. The incidence of adenoma or carcinoma (combined) was increased in 30 &mu;L male mice and the incidences of adenoma and of adenoma or carcinoma (combined) were increased in 7.5 and 15 &mu;L females. A positive dose-related trend in the incidence of adenoma or carcinoma (combined) was also observed in male mice. The incidence of basophilic hepatic foci was increased in 15 &mu;L male mice (0/50, 1/50, 9/50, 3/50). The increased incidence of liver neoplasms in this study was considered equivocal because the incidence of hepatocellular neoplasms in control and dosed males was within the historical range and because there was no clear dose-response relationship in females. No other treatment-related findings were observed in this study. 1-YEAR INITIATION/PROMOTION STUDY IN MALE SWISS (CD-1&reg;) MICE: Groups of 50 male mice were dosed dermally with diethylphthalate or dimethylphthalate to study their effect as initiators and promoters. Diethylphthalate and dimethylphthalate were tested as initiators with and without the known skin tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Diethyl phthalate and dimethylphthalate were tested as promoters with and without the known skin tumor initiator 7,12-dimethylbenzanthrancene (DMBA). Comparative control groups used during the study of diethylphthalate and dimethylphthalate included: vehicle control (acetone/acetone); initiation/promotion control (DMBA/TPA); initiator control (DMBA/acetone); and promoter control (acetone/TPA). Based on the incidence of skin neoplasms diagnosed histologically and the multiplicity of skin neoplasms, there was no suggestion that either diethylphthalate or dimethylphthalate was able to initiate skin carcinogenesis when chronically promoted by TPA. Further, there was no evidence that either diethylphthalate or dimethylphthalate was able to promote skin carcinogenesis in skin previously initiated with DMBA. High incidences of both squamous cell papillomas and squamous cell carcinomas occurred among the initiation/promotion control animals initiated with DMBA and promoted with TPA. All TPA-dosed groups had significantly greater incidences of dermal acanthosis, ulceration, exudation, and hyperkeratosis than controls. GENETIC TOXICOLOGY: Neither diethylphthalate (10-10,000 &mu;/plate) nor dimethylphthalate (33-6,666 &mu;/plate) induced gene mutations in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537, with or without rat and hamster liver S9. In cultured Chinese hamster ovary cells, both diethylphthalate and dimethylphthalate induced sister chromatid exchanges in the presence of S9. Neither induced sister chromatid exchanges in the absence of S9. Neither chemical induced chromosomal aberrations, with or without S9, in cultured Chinese hamster ovary cells. CONCLUSIONS: Under the conditions of these 2-year dermal studies, there was no evidence of carcinogenic activity of diethylphthalate in male or female F344/N rats receiving 100 or 300 &mu;L. The sensitivity of the male rat study was reduced due to low survival in all groups. There was equivocal evidence of carcinogenic activity of diethylphthalate in male and female B6C3F1 mice based on increased incidences of hepatocellular neoplasms, primarily adenomas. In an initiation/promotion model of skin carcinogenesis, there was no evidence of initiating activity of diethylphthalate or dimethylphthalate in male Swiss (CD-1&reg;) mice. Further, there was no evidence of promotion activity of diethylphthalate or dimethylphthalate in male Swiss (CD-1&reg;) mice. The promoting activity of TPA following DMBA initiation was confirmed in these studies. Minor dermal acanthosis was observed following dermal application of diethylphthalate in male and female F344/N rats dosed for 2 years and in male Swiss (CD-1&reg;) mice dosed for 1 year. Synonyms: Diethylphthalate (CAS No. 84-66-2): 1,2-benzenedicarboxylic acid, diethyl ester; DEP; diethyl 1,2-benzenedicarboxylate; diethyl o-phthalate; diethyl phthalate; ethyl phthalate; o-benzenedicarboxylic acid diethyl ester; phthalic acid, diethyl ester; RCRA U088 Dimethylphthalate (CAS No. 131-11-3): 1,2-benzenedicarboxylic acid, dimethyl ester; dimethyl 1,2-benzenedicarboxylate; dimethyl benzene-o-dicarboxylate; dimethyl benzeneorthodicarboxylate; dimethyl o-phthalate; dimethyl phthalate; DMP; FIFRA 028002; methyl phthalate; go-dimethyl phthalate; phthalic acid, dimethyl ester; phthalic acid methyl ester; RCRA U102

Journal Article↗
PubMed1997

C3H mice have larger spleens, lower platelet counts, and shorter platelet lifespans than C57BL mice: an animal model for the study of hypersplenism.

Several studies have shown that C3H mice have a modal megakaryocyte ploidy class of 32N as opposed to the 16N found in all other mouse strains tested. In addition to higher megakaryocyte DNA content, C3H mice are characterized by greater 35S-sulfate incorporation into platelets but somewhat lower platelet counts than C57BL mice. The aim of this study was to determine the etiology of mild thrombocytopenia in C3H mice. Several studies have indicated that an increase in platelet 35S incorporation parallels increased megakaryocyte ploidy. Thus the higher 35S incorporation by C3H mouse platelets is likely related to their higher megakaryocyte ploidy, but these differences do not explain the lower platelet counts observed in C3H mice. To elucidate the paradox of relatively low platelet counts in C3H mice despite elevated platelet 35S incorporation, we performed a hematological evaluation (including assessment of platelet counts and lifespans) and measured (relative) spleen size in C3H and C57BL mice. Our data confirm earlier reports of significantly lower platelet counts in C3H mice (p < 0.0005) compared with C57BL mice. We also found that C3H mice have larger spleens (p < 0.0005) than C57BL mice. Other groups of C3H and C57BL mice were splenectomized to determine the role of the spleen in decreasing platelet counts in C3H mice compared with C57BL mice. C3H mice had an average platelet lifespan of 4.8 days, which was significantly shorter (p < 0.01) than the 5.7-day platelet lifespan observed in normal C57BL mice. Platelet lifespans for splenectomized C3H mice were significantly (p < 0.005) longer than those found in intact C3H control mice, but splenectomy of C57BL mice had no effect on their platelet lifespans (p < 0.40). The lengthened platelet lifespans of splenectomized C3H mice indicate that the spleens of C3H mice were sequestering or destroying platelets at a faster rate than the spleens of C57BL mice. These data lead to the hypothesis that the relatively large spleens of C3H mice produce mild thrombocytopenia with increased platelet production (shorter platelet lifespan) compared with spleens of C57BL mice.

Animals↗
PubMed2006

Induction of scratching behaviour and dermatitis in various strains of mice cohabiting with NC/Nga mice with chronic dermatitis.

BACKGROUND: NC/Nga (NC) mice with similar pathological and behavioural features as seen in human atopic dermatitis are used as a model of the disease. Under normal circumstances, spontaneous and persistent scratching occurs in NC mice and this can lead to the onset of skin inflammation. OBJECTIVES: We examined the induction of scratching behaviour in NC, BALB/c, ICR and C3H/HeN mice, and of dermatitis in NC and BALB/c mice, by cohabitation with mice with dermatitis. METHODS: NC, BALB/c, ICR and C3H/HeN mice were kept together with NC mice with chronic dermatitis (CNV-NC) for 2 weeks, and the numbers of scratching episodes were counted. NC and BALB/c mice were also kept together with CNV-NC mice for 24 weeks and the skin severity score was assessed. The score was assessed for a further 8 weeks after separation of these mice. RESULTS: The number of scratching episodes in NC, BALB/c, ICR and C3H/HeN mice was increased by cohabitation with CNV-NC mice. Cohabitation with CNV-NC mice led to dermatitis in both NC and BALB/c mice. The number of scratching episodes and the skin severity score in BALB/c mice were about half of those in NC mice. When cohabitation with CNV-NC mice stopped, the number of scratching episodes and the skin severity score decreased in BALB/c mice, but not in NC mice. Changes in the histopathological data of BALB/c mice supported the severity of skin inflammation. CONCLUSIONS: Our study demonstrates that scratching behaviour and dermatitis can be induced in various strains of mice by cohabitation with CNV-NC mice, and that cessation of cohabitation leads to a recovery in BALB/c mice but not in NC mice.

Animals↗
PubMed1996

Influence of hypothalamus and ovary on pituitary function in transgenic mice expressing the bovine growth hormone gene and in growth hormone-deficient Ames dwarf mice.

Female transgenic mice expressing the bovine (b) growth hormone (GH) gene exhibit reduced fertility, and GH-deficient dwarf mice are sterile. However, in these animals, the influence of the hypothalamus and ovary on pituitary functions is poorly understood. To address this issue, female Ames dwarf mice received twice-daily injections of either vehicle or bGH (25 micrograms/injection per mouse) for 12 days. Vehicle-injected normal female siblings served as controls. On Day 7, these mice and adult female transgenic mice expressing the bGH gene with mouse metallothionein-I promoter, as well as their normal littermates, were ovariectomized. Two experiments were conducted with each group of mice: on Day 8 after ovariectomy of transgenic mice and their normal siblings, and on Day 4 after ovariectomy of dwarf mice and their normal siblings. In experiment I, mice were primed with 0.5 micrograms estradiol benzoate (EB) in oil and 24 h later received injections of 5 micrograms EB/100 g BW. The next day, these mice received injections of either saline or GnRH (1 ng/g BW), and 15 min later blood was obtained via heart puncture under anesthesia. In experiment II, ovariectomized mice either received injections of oil or were primed with 0.5 micrograms EB and 24 h later treated with 10 micrograms EB/100 g BW in oil. On the next day, blood was obtained as in experiment I. In transgenic mice and in their normal littermates, plasma bGH, FSH, LH, and prolactin levels were measured. In dwarf mice and in their normal siblings, plasma LH and insulin-like growth factor (IGF)-I levels were determined. Bovine GH was secreted in transgenic mice, but this hormone was not detectable in normal siblings. Expression of the GH gene resulted in attenuated (p < 0.001) FSH response to GnRH treatment, while LH response was similar to that in controls. The ovariectomy-induced increases in plasma FSH (p < 0.001) and LH (p < 0.05) levels were decreased in transgenic mice. The absolute circulating FSH levels were also decreased (p < 0.001) in estrogen-treated transgenic mice, while plasma LH level were similar in normal mice and in mice bearing the bGH gene. The ovariectomized transgenic mice were hyperprolactinemic. In ovariectomized dwarf mice, IGF-I was not detectable, and GH treatment induced its secretion. In these mice, plasma LH concentrations were reduced (p < 0.05), and GH treatment increased (p < 0.01) LH secretion. In oil-injected ovariectomized dwarf mice, the plasma LH response to GnRH treatment was reduced (p < 0.001), and GH administration normalized this response. The negative feedback effect of estrogen on LH secretion was decreased (p < 0.025) in dwarf mice. These indicate that the alterations in gonadotropin secretion are dependent on the duration of exposure of neuroendocrine system to bGH and that bGH alters the effects of GnRH and estrogen on gonadotropin secretion in these two widely divergent experimental mouse models.

Animals↗
PubMed2003

Mice with alterations in both p53 and Ink4a/Arf display a striking increase in lung tumor multiplicity and progression: differential chemopreventive effect of budesonide in wild-type and mutant A/J mice.

p53 transgenic mice carrying a dominant negative mutation were crossed with Ink4A/Arf heterozygous-deficient mice to investigate whether there is a synergy between these two germ-line mutations in promoting carcinogen-induced lung tumor progression in mice. Mice with a p53 dominant negative mutation and Ink4A/Arf heterozygous deficiency exhibited >20-fold increase in tumor volume compared with approximately 4-fold increase in Ink4A/Arf heterozygous-deficient mice and a 9-fold increase in mice with only the p53 dominant negative mutation. The effect of Ink4A/Arf heterozygous deficiency on lung tumor progression occurred late in the carcinogenesis process (>30 weeks after carcinogen treatment). In addition, most of the lung tumors (approximately 80%) from mice with a p53 mutation and deletion of Ink4A/Arf were lung adenocarcinomas. In contrast, lung adenocarcinomas were seen in <10% of the lung tumors from the wild-type mice and approximately 50% of the lung tumors from Ink4a/Arf heterozygous-deficient or p53 mutant mice. These results indicate a significant synergistic interaction between the presence of a mutant p53 transgene and the Ink4A/Arf deletion during lung tumor progression (P < 0.01). The usefulness of this new mouse model in lung cancer chemoprevention was examined. The chemopreventive efficacy of budesonide was examined in wild-type mice, mice with Ink4A/Arf heterozygous deficiency, mice with a mutation in the p53 gene, or mice with both a mutation in the p53 gene and deletion in the Ink4A/Arf locus. Mice treated with budesonide displayed an average of 90% inhibition of lung tumor progression in a standard 18-week chemoprevention assay, regardless of p53 and/or Ink4A/Arf status. However, the efficacy of budesonide against lung tumor progression decreased from 94 to 77% (P = 0.07) in mice with alterations in both p53 and Ink4A/Arf in a 40-week chemoprevention assay. Similarly, when mice bearing established lung adenomas were treated with budesonide, genotype-dependent differential effects of budesonide in wild-type and mutant mice were clearly revealed with a 82, 64, 45, and 33% decrease in tumor volume in wild-type mice, p53(+/+)Ink4a/Arf(+/-) mice, p53(+/-)Ink4a/Arf(+/+) mice, and p53(+/-)Ink4a/Arf(+/-), respectively. Thus, mutant mice with alterations in p53 and/or Ink4A/Arf exhibited a significant resistance to chemoprevention by budesonide. Because p53 and Ink4a/Arf mutations are the most prevalent mutations in human lung cancers, the effectiveness of chemopreventive agents on the mutant A/J mice containing alterations with p53 and Ink4a/Arf is the best preclinical estimate of their efficacy in humans. Thus, the mutant A/J mouse model should prove useful for chemoprevention studies.

Adenocarcinoma↗
PubMed1989

The renal phosphate transport defect in normal mice parabiosed to X-linked hypophosphatemic mice persists after parathyroidectomy.

The X-linked hypophosphatemic (Hyp) mouse is a model for human X-linked hypophosphatemia. Surgical joining of normal to Hyp mice by parabiosis results in the normal mice developing low renal retention of phosphate and hypophosphatemia. These results suggest a humoral component to the renal defect. To test whether this component could be parathyroid hormone, surgical parathyroidectomy (PTX) or sham surgery was performed in mice 3 weeks after parabiotic union (n greater than 20 per group). After an overnight fast, PTX mice were hypocalcemic and hyperphosphatemic relative to sham-operated control mice. PTX normal mice joined to PTX Hyp mice were significantly lower in plasma phosphate and higher in fractional excretion of phosphate [U/P phosphate/(U/P creatinine)] when compared with PTX normal mice joined to other PTX normals. To test for more specific evidence of altered renal transport function, renal brush-border membrane vesicles (BBMV) were prepared from these mice, and phosphate and glucose uptakes were measured. The phosphate/glucose transport ratio was lower in BBMV from Hyp mice, joined to either normal mice or to Hyp mice, when compared with that from normal-normal pairs. Moreover, BBMV from normal mice joined to Hyp mice had a significantly lower phosphate/glucose uptake ratio than BBMV from normal mice joined to other normal mice, and their activity approached that of BBMV derived from Hyp mice. Glucose uptake in BBMV was unaffected by parabiosis or genotype. In summary, parabiosis of normal mice to Hyp mice resulted in the development of phosphaturia and decreased BBMV phosphate transport in the normal mice. The persistence of the phosphate transport defect in parathyroidectomized mice suggests that parathyroid hormone is not the humoral factor contributing to these results.

Alkaline Phosphatase↗
PubMed1997

Differential effects of human interferon alpha and interferon gamma on xenografted human thyroid tissue in severe combined immunodeficient mice and nude mice.

We have studied the in vivo effects of human interferon alpha (IFN-alpha) and interferon gamma (IFN-gamma) administration on human thyroid tissue xenografted into two mouse strains: severe combined immunodeficient (SCID) mice and nude mice. Human lymphocytes survive in SCID mice but are lysed in nude mice. Thyroid tissues from Graves' disease or Hashimoto's thyroiditis, or paranodular [normal, (N)] tissue was xenografted into SCID mice (0.8 g/mouse) pretreated with anti-asialo GM-1 antiserum and radiation and also into nude mice. One week after xenografting, SCID and nude mice were divided into three groups. Group A was treated with IFN-alpha intraperitoneally (2,000 units/mouse) three times weekly; group B was treated with IFN-gamma similarly; group C was treated with phosphate buffered saline (PBS) only (control). Autologous human peripheral blood mononuclear cells (PBMCs) were added to mice receiving N xenografts. Blood was taken every 2 weeks for levels of IgG and thyroid antibodies (TAb). After 6 weeks of treatment, mice were sacrificed, and xenograft thyrocyte histocompatibility leukocyte antigen (HLA-DR) and intercellular adhesion molecule (ICAM-1) expression were measured. In addition, thyrocyte cultures were stimulated in vitro with 200 units/ml of either IFN-alpha or IFN-gamma or PBS (control). SCID mice xenografted with autoimmune thyroid disease (AITD) in group A showed a significantly higher TAb production than group C, whereas in group B, TAb production was not statistically increased compared to control (group C). SCID mice xenografted with N did not produce TAb in any group, nor did nude mice xenografted with AITD. Thyrocyte HLA-DR expression was markedly increased in group A and B in SCID mice xenografted with Graves' disease, Hashimoto's thyroiditis, and N tissue compared to group C. In contrast, only group B (IFN-gamma) showed an increase in thyrocyte HLA-DR in nude mice. In the in vitro studies, only IFN-gamma (not IFN-alpha) stimulated thyrocyte HLA-DR and ICAM-1 expression in Graves' disease, Hashimoto's thyroiditis, and N tissues. We concluded that in SCID mice, IFN-alpha causes TAB production in AITD xenografts but not in N xenografts, while increasing thyrocyte HLA-DR expression in both. Also, IFN-gamma does not cause a statistically increased TAb in AITD xenografts in SCID mice, despite a sharp rise in thyrocyte HLA-DR expression. In addition, because IFN-alpha has no effect in nude mice or in vitro on thyrocyte HLA-DR expression, its effects in SCID mice must be mediated via local infiltrating lymphocytes. Finally, IFN-gamma has a direct effect on thyrocytes to increase HLA-DR expression (and, in vitro, ICAM-1 expression) but may not stimulate TAb production.

Adolescent↗
PubMed1984

Studies of congenitally immunologically mutant New Zealand mice. IX. Age-related microenvironmental effects on autoantibody production in NZB and NZB.Xid mice studied by transplantation.

The mechanism of polyclonal expansion of B cells and subsequent autoantibody production in New Zealand mice remains a critical question. We have been studying the requirements for autoantibody production both in NZB mice as well as NZB mice congenic with the Xid gene of CBA/N mice. In this study, we have attempted to alter the immunologic phenotype of NZB.Xid mice by transfer of cells from young and old NZB mice. There was little difficulty in restoring normal levels of serum IgM, IgG3, splenic Lyb-5 cells, and response to DNP-Ficoll in young NZB.Xid mice that were injected with young NZB bone marrow cells. Although such animals had an almost immediate change in their immune profile to values characteristic of NZB mice, they required, much like unmanipulated NZB mice, a latency period of an additional 6 mo before autoantibodies were detected. In contrast, adult NZB.Xid mice, who likewise developed an immune profile similar to NZB after transfer of bone marrow cells from young NZB mice, began to express autoantibodies immediately without any latency period. NZB.Xid mice who were recipients of adult NZB bone marrow cells did not show sustained autoantibody production, reflecting the limited state of B cell precursors in adult NZB mice. Thus, the age of both donor cells and the age of recipient mice are critical factors for determining the latency period and the age at which autoantibodies will appear. Similarly we attempted to alter the production of autoantibodies in NZB mice that were irradiated and injected with bone marrow cells from NZB.Xid animals. NZB mice had a major amelioration of disease when they received cell transfers from young NZB.Xid mice. This amelioration, which included the acquisition of the immune profile of NZB.Xid animals, was not seen in adult NZB mice that were recipient of young NZB cells. We suggest that although Lyb-5 cells may be the effective mechanism for autoantibody production, there are other interacting influences that may selectively turn on or turn off autoantibodies and that are required and are responsible for the latency period.

Aging↗
PubMed1995

The Hcr (hepatocarcinogen resistance) loci of DBA/2J mice partially suppress phenotypic expression of the Hcs (hepatocarcinogen sensitivity) loci of C3H/HeJ mice.

Both male DBA/2J and C3H/HeJ mice are highly susceptible to hepatocarcinogenesis induced by experimental treatment with N,N-diethylnitrosamine (DEN) relative to male C57BL/6J mice. While C3H/HeJ mice carry multiple sensitivity loci, designated Hcs (hepatocarcinogen sensitivity), our previous study indicated that the susceptibility of DBA/2J mice results from the combined effects of multiple sensitivity loci and two major resistance loci, Hcr-1 and -2 (hepatocarcinogen resistance). We proposed that BXD-15 recombinant inbred mice, which are extremely resistant to DEN-induced hepatocarcinogenesis, may carry the Hcr loci from the parental DBA/2J mice, but few, if any, of the multiple sensitivity loci. Conversely, the extremely sensitive BXD-11 recombinant inbred mice may carry most of the multiple sensitivity loci of the DBA/2J parents, but neither of the major resistance loci. In order to confirm our genetic model for hepatocarcinogenesis in DBA/2J mice and to evaluate the phenotypic effects of the Hcr loci on the Hcs loci of C3H/HeJ mice, we characterized hepatocarcinogen sensitivities of F1 mice generated from the crosses involving BXD-11, BXD-15, C3H/HeJ and C57BL/6J strains. When male mice were initiated with DEN at 12 days of age and liver tumors were enumerated at 32 weeks of age, (BXD-15 x BXD-11)F1 mice had one sixth the number of liver tumors observed in (C57BL/6J x BXD-11)F1 mice, consistent with our previous conclusion that DBA/2J mice possess hepatocarcinogen resistance genes in spite of their high susceptibility to DEN. Significantly, (C57BL/6J x C3H/HeJ)F1 mice also had a 2.3-fold greater number of liver tumors and 5.5-fold higher total volume of initiated lesions per liver as compared with (BXD-15 x C3H/HeJ)F1 mice, indicating that the hepatocarcinogen resistance genes inherited by BXD-15 mice are capable of suppressing the Hcs phenotype. Thus the Hcr loci may influence a wide variety of hepatocarcinogen sensitivity loci and be able to act as general resistance loci for chemical hepatocarcinogenesis. Stereological analysis of initiated hepatocellular lesions with glucose 6-phosphatase deficiency revealed that the resistance genes largely influence the promotion stage of hepatocarcinogenesis.

Animals↗
PubMed1996

Dialyzable lymphoid extract (DLE) from mice resistant to STZ-induced diabetogenesis can interrupt the progress of diabetes in STZ-treated CD-1 mice.

DLE was prepared from the minority of euglycemic CD-1 mice, previously injected with STZ, and was administered to hyperglycemic CD-1 male mice 1, 2 and 3 weeks after completion of multidose STZ. Mice treated with DLE derived from 2 x 10(7) (IX) or 10(8) lymphocyte equivalents (lymph.equ) were significantly less hyperglycemic than the saline treated controls (P < 0.001). The effects of DLE remained evident for more than 10 weeks after the final DLE treatment. Mice treated with DLE prepared from diabetic mice (hg DLE) developed a somewhat more rapid onset of hyperglycemia than the STZ treated control animals, although this effect did not achieve statistical significance (P = 0.1). This DLE was absorbed on a rat insulinoma cell line (RIN), which contains interspecies cross-reacting islet antigens, and compared to the unabsorbed DLE. Mice treated with hg DLE preabsorbed on RIN cells, showed a slower onset of hyperglycemia. DLE prepared from euglycemia mice and the RIN-absorbed fraction were equally capable of preventing hyperglycemia (P < 0.05). In order to determine whether the DLE effects were genetically restricted, DLE was prepared from BALB/c mice, normally resistant to the diabetogenic effects of multidose STZ, both before and after STZ treatment. STZ primed CD-1 mice treated with 3 weekly doses of 2 x 10(7) lymph. equ. of untreated BALB/c derived DLE, STZ treated BALB/c derived DLE, and STZ treated CD-1 DLE were all less hyperglycemic than the control mice, who received saline (P < 0.001). However, mice treated with CD-1 DLE were less hyperglycemic than the mice given BALB/c derived DLE (P < 0.05). These effects were relatively long-lived. Mice that were given the > 3,500 Dalton fraction of CD-1 DLE were significantly less hyperglycemic than either the control mice or those treated with the < 3,500 Dalton fraction of CD-1 DLE (P < 0.05). Effects remained evident for more than 3 months after the last dose of DLE. Pancreatic tissue from the mice treated with the > 3,500 Dalton fraction of CD-1 derived DLE revealed slightly more islets of a slightly greater size with less surrounding inflammation than either control mice or mice treated with the < 3,500 Dalton fraction of DLE.

Animals↗