Strain difference in sensitivity of mice to renal toxicity of inorganic mercury

Inorganic mercury has a high affinity for the kidneys and causes acute renal failure. The present investigation was designed to determine the cause of the strain difference in sensitivity of mice to the renal toxicity of inorganic mercury. Renal damage caused by HgCl2 was estimated by histopathological and biochemical assessment, such as increase in blood urea nitrogen and plasma creatinine levels, and was found to be more remarkable in C3H/He than in C57BL/6 mice. Increase in renal lipid peroxidation in C3H/He was greater than that in C57BL/6 mice. However, no strain difference was observed in renal activities of glutathione (GSH) peroxidase, superoxide dismutase and GSH S-transferase in HgCl2-untreated mice. The GSH content and activities of catalase and GSSG reductase in kidney of HgCl2-untreated mice were higher in C3H/He than in C57BL/6. Background level of renal metallothionein content and the extent of metallothionein induction by HgCl2 showed no strain difference. On the other hand, renal mercury accumulation was higher and urinary mercury excretion was lower in C3H/He than in C57BL/6. The activity of renal gamma-glutamyltranspeptidase (gamma-GTP), which plays a key role in renal mercury accumulation, was higher in C3H/He than in C57BL/6. Furthermore, the increase in blood urea nitrogen by HgCl2, renal mercury accumulation and renal gamma-GTP activity in B6C3F1 mice were intermediate between those of the parent strains. These results suggest that the strain difference in renal toxicity of inorganic mercury seems to be caused by the discrepancy in renal mercury accumulation, and therefore, renal gamma-GTP may be an important factor determining the susceptibility of mice to the toxic action of inorganic mercury.     

High susceptibility of p53(+/-) knockout mice in N-butyl-N-(4-hydroxybutyl)nitrosamine urinary bladder carcinogenesis and lack of frequent mutation in residual allele

The loss of p53 functions is considered to compromise the growth-suppression machinery of the cell and facilitate neoplastic change. In humans, genetic alteration in the p53 gene is one of the most frequently observed molecular changes in tumors, including urinary bladder carcinomas. We have investigated the susceptibility of heterozygote p53 knockout mice to N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in terms of urinary bladder tumor induction. Both p53(+/-) knockout mice and C57BL/6 original parent strain were administered 0, 0.002, 0.004, 0.0075 and 0.025% BBN in the drinking water for 20 weeks. As compared with the C57BL/6 strain, greater lesion yields were observed in knockout mice after 20 weeks of treatment. Transitional cell carcinomas were found in 9 (75%) and 12 (100%) of each 12 mice of the 0.0075 and 0.025% BBN treatment groups, respectively, whereas only 1 (11%) and 6 (67%) of each 9 of the C57BL/6 mice demonstrated tumors. Preneoplastic lesions (dysplasia) were also observed more frequently in the lower dose groups in the knockout mice than C57BL/6 mice. PCR single-strand conformation polymorphism analysis followed by DNA direct sequencing of the p53 gene (exons 5-8) extracted from bladder tumors demonstrated mutations in 3 of 11 (27.3%; exon 7) and 8 of 29 (27.6%; exons 5-8) tumors in C57BL/6 and knockout mice, respectively. There was no significant difference in the mutation rates at the residual p53 gene between the two cases. All mutations observed in knockout mice were restricted to the normal allele, and none were present in the gene-targeted null allele. In a separate experiment, 5-bromo-2'-deoxyuridine labeling indices after treatment with BBN for 2 or 4 weeks were significantly higher in knockout mice than wild-type mice. Measurement of the urinary concentration of N-butyl-N-(3-carboxypropyl)nitrosamine, a proximate carcinogenic metabolite, revealed no significant differences between knockout and original parent strain after administration of 0.0075% BBN in the drinking water for 4 weeks. In conclusion, knockout mice are distinctly more sensitive to urinary bladder carcinogenesis induced by BBN than their original parent strain, as evidenced by elevated DNA synthesis during carcinogen administration and an increased tumor yield. The high susceptibility of p53 knockout mice appeared to be related to the high level of cell proliferation rather than that of N-butyl-N-(3-carboxypropyl)nitrosamine in the urine or that of mutations at the p53 gene.     

Clonal expansions of B lymphocytes in old mice

The effect of age on the diversity of the murine Ig heavy chain repertoire has been studied in unimmunized C57BL/6 mice. We examined the heterogeneity of complementarity-determining region 3 (CDR3) sizes of Ig mRNA of the IgM and IgG isotypes using two VH families, VHJ558 and VHQ52, which together account for approximately 65% of the Ab repertoire. The broad and bell-shaped profiles representing the diversity of the VHJ558 family in the spleen of 2- to 6-mo-old C57BL/6 mice becomes significantly less diverse after 12 mo of age and by 18 mo of age, single CDR3 sizes that dominate the profiles can be observed in the spleens of > 85% of the mice. Readable sequences have been obtained from 40 dominant mRNA CDR3 size species indicating that they represent clonal populations of B lineage. There are no significant homologies among these sequences. Clones of B lymphocytes that express a dominant CDR3 mRNA species can also be found in the bone marrow, the mesenteric lymph nodes, and the thymus of C57BL/6 mice > 18 mo of age. Some clones of B cells can be detected in only one lymphoid compartment; others are found in two or more compartments. The splenic B cell clones in C57BL/6 mice > 18 mo of age are stable for at least 2 mo. The CDR3 mRNA species that dominate the splenic repertoire of Ig mRNA-expressing cells in vivo do not dominate the repertoire of splenic B cells activated in vitro by bacterial LPS, suggesting that they represent a modest population of B cells expressing high levels of Ig mRNA.     

A high-resolution map in the chromosomal region surrounding the Lps locus

The Lps locus on mouse chromosome 4 controls host responsiveness to lipopolysaccharide, a major component of the outer membrane of Gram-negative bacteria. The C3H/HeJ inbred mouse strain is characterized by a mutant Lps allel (Lpsd) that renders it hyporesponsive to LPS and naturally tolerant of its lethal effects. To identify the Lps gene by a positional cloning strategy, we have generated a high-resolution linkage map of the chromosomal region surrounding this locus. We have analyzed a total of 1604 backcross mice from a preexisting interspecific backcross panel of 259 (Mus spretus x C57BL/6J)F1 x C57BL/6J and two novel panels of 597 (DBA/2J x C3H/HeJ)F1 x C3H/HeJ and 748 (C57BL/6J x C3H/HeJ)F1 x C3H/HeJ segregating at Lps. A total of 50 DNA markers have been mapped in a 11.8-cM span overlapping the Lps locus. This positions the Lps locus within a 1.1-cM interval, flanked proximally by a large cluster of markers, including three know genes (Cd301, Hxb, and Ambp), and distally by two microsatellite markers (D4Mit7/D4Mit178). The localization of the Lps locus is several centimorgans proximal to that previously assigned.     

Changes in hepatic enzyme activities related to ethanol metabolism in mice following chronic ethanol administration

Male mice of three strains, C57BL, DBA and C3H/He, were fed on commercial food with 10% (v/v) ethanol solution as drinking liquid ad libitum for eighty days, and the changes in the activities of enzymes in the metabolic pathway of ethanol in the liver were examined. C57BL and C3H/He mice showed a preference for drinking the 10% (v/v) ethanol solution, while DBA mice did not. The ethanol intake g/g of body weight of C3H/He mice showed the highest value among all three strains and that of C57BL mice tended to show higher value than that of DBA mice. The liver weights of C57BL and C3H/He mice increased significantly following chronic ethanol administration, but that of DBA did not. The cytosolic enzyme alcohol dehydrogenase (ADH) showed no changes in any of the strains following chronic ethanol administration. The microsomal ethanol-oxidizing system (MEOS) of C57BL mice exhibited approximately 2-fold higher activity compared to that of DBA and C3H/He mice but did not increase in any strain following chronic ethanol administration. However, the microsomal aniline hydroxylase activity in the liver increased significantly in C57BL and C3H/He mice following chronic administration of ethanol. The microsomal cytochrome P-450 content also tended to slightly increase in the same strains of mice. It seemed that cytochrome P-450IIE1 was induced in the liver microsomes of these strains. Total aldehyde dehydrogenase (ALDH) activities together with high-Km ALDH activity increased markedly in the microsomes of C57BL mice and tended to increase in C3H/He mice, while it did not change in DBA mice following chronic ethanol administration. In the mitochondria of C57BL, total ALDH activities increased slightly and high-Km ALDH activities tended to increase. These mitochondrial ALDH activities of C3H/He and DBA mice tended to increase following chronic ethanol administration. The cytosolic ALDH activity showed no changes in any strain of mice following chronic ethanol administration. It seemed that in the microsomes, the activities of enzymes related to oxidation of ethanol increased in C57BL and C3H/He mice, which tended to consume a large amount of ethanol, and did not in DBA mice which tended to consume a small amount of it. It seemed that the increases in activities of enzymes related to oxidation of acetaldehyde in the microsomes and in the mitochondria were responsible for the strain difference.     

Defective LPS signaling in C3H/HeJ and C57BL/10ScCr mice: mutations in Tlr4 gene

Mutations of the gene Lps selectively impede lipopolysaccharide (LPS) signal transduction in C3H/HeJ and C57BL/10ScCr mice, rendering them resistant to endotoxin yet highly susceptible to Gram-negative infection. The codominant Lpsd allele of C3H/HeJ mice was shown to correspond to a missense mutation in the third exon of the Toll-like receptor-4 gene (Tlr4), predicted to replace proline with histidine at position 712 of the polypeptide chain. C57BL/10ScCr mice are homozygous for a null mutation of Tlr4. Thus, the mammalian Tlr4 protein has been adapted primarily to subserve the recognition of LPS and presumably transduces the LPS signal across the plasma membrane. Destructive mutations of Tlr4 predispose to the development of Gram-negative sepsis, leaving most aspects of immune function intact.     

Characteristics of women choosing birth center care

Certain strains of mice, designated V beta a, have a deletion of the gene segments encoding the beta chain of the T-cell receptor variable region. These mice do not express 40 to 50% of the T-cell receptor V beta chains. In this study, we examined the influence of this deletion on susceptibility to Histoplasma capsulatum. In addition, H. capsulatum-injected V beta a mice were tested for their capacity to generate T-cell dependent responses to H. capsulatum antigens. Susceptibility profiles of V beta a mice, SWR/J (H-2q), SJL/J (H-2s) and C57L-(H-2b), were compared to V beta b strains, C57BL/6 (H-2b) and DBA/l (H-2q), following intravenous (IV) injection of sublethal and lethal inocula of H. capsulatum yeast cells. One week after injection of 6 x 10(5) yeast cells, the spleens of SWR/J, SJL/J and C57L mice contained 5- to 7-fold fewer colony forming units (CFU) than spleens of C57BL/6 mice. Approximately 50% fewer CFU of H. capsulatum were recovered from the spleens of DBA/l mice compared to those from C57BL/6 animals. Subsequently, groups of mice were challenged IV with either 1.5 x 10(7) or 7.5 x 10(6) yeast cells and observed for 30 days. Survival of SWR/J,SJL/J, C57L and DBA/l mice was significantly prolonged compared to C57BL/6 mice. V beta a and DBA/l mice injected with viable H. capsulatum yeast cells mounted a delayed-type hypersensitivity response to an extract from the cell wall and cell membrane of yeast cells and to HIS-62, a purified antigen derived therefrom.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic differences in nicotine-induced conditioned taste aversion

Genetic differences in nicotine-induced conditioned taste aversion were examined using inbred mice. Adult male C57BL/6J, DBA/2J, BALB/cJ and C3H/heJ mice were adapted to a 2-h per day water access regimen. Subsequently, mice received nicotine injections (0.5, 1.0 or 2.0 mg/kg) immediately after 1-h access to a NaCl flavored solution. DBA and C3H mice developed dose-dependent aversions to the nicotine-paired flavor. BALB mice showed only minor reductions in intake with no difference between the nicotine dose groups. C57BL mice did not show development of nicotine-induced conditioned taste aversion. These results demonstrate that nicotine's aversion motivational effect is strongly influenced by genotype. Further, genetic sensitivity (DBA mice) or insensitivity (C57BL mice) to nicotine-induced conditioned taste aversion was similar to reports of genetic sensitivity to ethanol's aversive effect measured in this design.     

Beta 2-microglobulin knockout mice are highly susceptible to polyoma virus tumorigenesis

Polyoma virus is highly oncogenic when inoculated into immunocompromised adult mice and neonatal mice of specific inbred strains. Although T lymphocytes are known to be essential in controlling polyoma virus tumorigenesis, the importance of class I MHC-restricted CD8+ T cells in mediating tumor resistance remains unclear. Here, we investigated the tumorigenicity of polyoma virus in adult mice rendered CD8+ T cell-deficient by homozygous (-/-) disruption of the beta 2-microglobulin (beta 2m) or CD8 alpha (CD8) genes. Nearly all (94%) of the virus-infected adult C57BL/6 beta 2m-/- mice developed tumors, and 20% of the virus-inoculated adult C57BL/6CD8-/- mice developed hindlimb paralysis, which is indicative of vertebral tumors. Only 2 of 20 virus-inoculated adult normal C57BL/6 mice developed tumors. Despite these different tumor susceptibilities, persistent viral DNA was detected in multiple organs of mice of all three strains. Multifocal lymphoplasmacytic interstitial infiltrates were present in the kidneys and lungs of virus-infected C57BL/6 beta 2m-/- and in the lungs of virus-inoculated C57BL/6CD8-/- mice. These infiltrates were composed primarily of B cells and colocalized with staining for the major viral capsid protein, VP1. No infiltrates or VP1 staining was detected in the kidneys of infected C57BL/6 mice. Using a highly sensitive RT-PCR bioluminescence immunoassay, we investigated and detected persistent polyoma T protein and VP1 messages in both C57BL/6 beta 2m-/- and C57BL/6 mice. C57BL/6 beta 2m-/- and C57BL/6 mice had equivalent serum virus-neutralizing antibody titers. These results provide in vivo evidence that class I MHC-restricted CD8+ T cells are involved in mediating protection against polyoma virus tumor development.     

The protein efficiency ratios of 30:70 mixtures of animal:vegetable protein are similar or higher than those of the animal foods alone

C57BL/6 mice receiving pretransplant immunization with C3H.SW spleen cells via the portal vein, but not the vena cava, show Ag-specific delayed rejection of allogeneic C3H.SW skin grafts. This delayed rejection is not seen if preimmunization is performed in gamma delta TCR knockout (C57BL/6-Tcrdtm1Mom) mice. gamma delta TCR+ and alpha beta TCR+ hybridoma cells were prepared from Peyer's patch cells harvested from C57BL/6 mice 4 days following portal venous immunization with 100 x 10(6) irradiated C3H.SW spleen cells and skin grafting with C3H.SW tail skin. After recloning, these hybridoma cells were tested for cytokine production in vitro following restimulation with irradiated C3H.SW spleen cells and for their ability to delay rejection of C3H.SW skin grafts after adoptive transfer to C57BL/6 mice. Delayed graft rejection was a function of cells that showed preferential production of IL-10, not IFN-gamma, in vitro, independent of the source (vena cava or portal vein immunized mice) or the TCR phenotype of the hybridoma. Simultaneous infusion of anti-IL-10 mAb abolished this graft prolongation effect of transferred gamma delta TCR+ hybridomas. Hybridoma cells producing IL-10 on restimulation could polarize cytokine production from freshly stimulated mesenteric lymph node away from production of IL-2 and IFN-gamma, and toward IL-4, IL-10, and TGF-beta production. This immunoregulation by hybridoma cells in vivo and in vitro was observed even for third party Ag-stimulated mice/cells as long as the hybridoma cells themselves received stimulation with their specific Ag.     

Differential antigen recognition by T cell populations from strains of mice developing polar forms of granulomatous inflammation in response to eggs of Schistosoma mansoni

In humans, infection with schistosome helminths can lead to dissimilar forms of clinical disease. Likewise, in the experimental mouse system, identical infection protocols with Schistosoma mansoni cause a more severe granulomatous disease in the C3H strain than in the C57BL/6 strain. To address this difference, we developed panels of schistosomal egg antigen (SEA)-specific T cell hybridomas to compare the responses of C3H and C57BL/6 mice to the major egg antigen p40. All derived C3H T cell hybridomas, despite being clonally distinct and restricted by either I-Ak or I-Ek, responded to recombinant fragment 15-1 of the p40 antigen, while none of the C57BL/6 T cell hybridomas did. Consistent with the observed monoclonal T cell responses, polyclonal lymph node cells from schistosome-infected C3H mice reacted strongly to fragment 15-1, which contrasted sharply with the weak response displayed by the C57BL/6 strain. Moreover, studies with congenic mice demonstrated that the strong CD4+ T cell response to fragment 15-1 was under major histocompatibility complex control and segregated with the H-2k haplotype. These findings suggest that a dominant T cell response against a major egg antigen may represent a risk factor for the development of severe disease.     

Evidence for the genetic control of estradiol-regulated responses. Implications for variation in normal and pathological hormone-dependent phenotypes

The ovarian steroid hormone estrogen (E2) elicits a multiplicity of both systemic and uterotropic responses in vivo. For example, the administration of E2 to ovariectomized (Ovx) and sexually immature rodents leads to uterine-specific inflammatory infiltrates. In this study, we quantitated the number of eosinophils and BM8+, Ia+, and CD4+ cells in uteri obtained from adult Ovx control and E2-treated C57BL/6J, C3H/HeJ, and (C57BL/6J x C3H/HeJ) (B6C3) F1 hybrid mice. All three strains exhibited a significant increase in the number of uterine eosinophils and BM8+ macrophages after E2 treatment. However, C57BL/6J and B6C3 F1 hybrid mice responded with a greater number of infiltrating eosinophils and macrophages as compared with C3H/HeJ. A similar analysis of Ia+ and CD4+ cells showed that E2 treatment either down-regulates or does not affect the number of such cells in all three strains. Genome exclusion mapping using a (C57BL/6J x C3H/HeJ) x C3H/HeJ backcross population localized Est1, the major locus controlling the number of eosinophils infiltrating the uterus after E2 treatment, to chromosome 4. In addition, suggestive linkage to marker loci on chromosomes 10 and 16 was detected and evidence for locus interaction is presented. Our results conclusively demonstrate that E2-regulated/ dependent responses can be genetically controlled, indicating that the phenotypic variation observed in both the normal and pathological effects of E2 may, in part, be due to a genetic component.     

Femoral abnormalities and vitamin D metabolism in X-linked hypophosphatemic (Hyp and Gy) mice

X-linked hypophosphatemia is a genetic bone disease in humans and mice. Two closely linked mutations in mice, Hyp and Gy, cause low plasma phosphate and a rachitic and osteomalacic bone disease. Because of the controversy as to whether Gy is a good model for X-linked hypophosphatemia, the phenotypic severity of these two mutations was compared in both sexes and on two genetic backgrounds. The depression in plasma levels of phosphate was similar in all 10-week-old mutant mice. Male Hyp mice and heterozygous female Hyp mice were affected with similar severity in terms of reduced tail growth, shortened femora, reduced femoral mineral content, and abnormal mineral composition of the femoral matrix. In contrast, male Gy mice did not survive on the C57BL/6J background and were more severely affected than female Gy mice on the B6C3H background. The hybrid B6C3H background ameliorated the bone disease compared with the inbred C57BL/6J background for both mutant strains. There was no evidence of change in the plasma levels of 1,25-dihydroxyvitamin D, duodenal level of vitamin D-dependent calcium-binding protein, or urinary level of calcium in these adult mutant mice. In summary, Gy mice have a sexual dimorphism not present in Hyp mice. These two genes may indicate the presence of multiple gene loci in the human disease, with multiple proteins involved in the pathophysiology of the bone disease.     

Sensitivity to tumor promotion of SENCAR and C57BL/6J mice correlates with oxidative events and DNA damage

Significant differences in sensitivity to multistage carcinogenesis have been noted between mice that are sensitive (SENCAR) and resistant (C57BL/6J) to 12-O-tetradecanoylphorbol-13-acetate (TPA). However, the mechanism of this sensitivity has not yet been established. Recent studies from this laboratory have shown that TPA significantly enhances formation of hydrogen peroxide (H2O2) and oxidized DNA bases in SENCAR mouse skin, as it increases the infiltration of polymorphonuclear leukocytes (PMNs), as quantitated by myeloperoxidase (MPO). In the studies reported here, we compared SENCAR and C57BL/6J mice with respect to TPA-mediated edema, hyperplasia, PMN infiltration, oxidant formation and oxidative DNA damage in mouse skin. Topical application of two TPA doses (2x2-40 micrograms, 20 h apart) dose-dependently increased PMN infiltration and oxidant formation in both mouse strains, which was consistent with TPA-induced morphological alterations (edema and hyperplasia). However, at low TPA doses (2-4 micrograms), the increases over controls in the SENCAR mice were significantly greater (P < 0.01) than those in C57BL/6J mice. Comparison of the net values indicated that 4 micrograms TPA enhanced PMN infiltration (MPO units/cm2) and oxidant formation (nmol H2O2/cm2) in SENCAR mice by 7.7- and 11-fold respectively over those present in TPA-treated C57BL/6J mouse skin. At the same dose, TPA also significantly increased formation of thymidine glycol (dTG; 5.5-fold), 5-hydroxymethyl-2'-deoxyuridine (HMdU; 4.9-fold) and 8-hydroxyl-2-deoxyguanosine (8-OHdG; 11.4-fold) in SENCAR mouse epidermis. Then, the levels of all three declined. In C57BL/6J mice, there were virtually no increases at 4 micrograms TPA, but their levels gradually increased with higher TPA doses and reached maxima at 10 micrograms TPA for dTG (1.9-fold increase), at 20 micrograms TPA for 8-OHdG (6.0-fold), and at 30 micrograms TPA for HMdU (1.8-fold). We conclude that the TPA-mediated oxidative events and oxidative DNA modification by different doses of TPA correlate with the promoting potencies of those doses in both mouse strains. Therefore, they could be, at least in part, responsible for the strain-dependent sensitivity to tumor promotion.     

Detection of new spider toxins from a Nephilengys borbonica venom gland using on-line mu-column HPLC continuous flow (FRIT) FAB LC/MS and MS/MS

The Morris water maze is frequently used to screen mutant mice generated by gene targeting. Targeted ES-cells are often derived from 129/Sv or BALB/c mice, known as poor swimming navigation learners. After mating the founders with C57BL/6 mice, the F2 or F3 hybrid generation is typically used for behavioral testing. In hybrid 129/Sv x C57BL/6 mice, a modification of the betaAPP gene entails impaired swimming navigation learning. This is readily detected despite behavioral variability, because wild-type 129/Sv x C57BL/6 hybrids outperform either of the parental strains and provide a control sample with good baseline performance. However, after backcrossing to the 129/Sv(ev) strain, the mutation effects are no longer detectable, masked by the very poor performance of wild-type 129/Sv(ev) mice. We conclude that F2 and F3 generations of 129/Sv x C57BL/6 crosses provide a suitable genetic background for behavioral testing of transgenic mice, provided that the samples are large enough to compensate for genetic and epigenetic variability and provided that normal performance in the control group is verified by comparison against a large database of mice tested under identical conditions. Creating congenic lines by backcrossing to an inbred strain is unlikely to enhance the sensitivity of the Morris test. Backcrossing to 129/Sv(ev) may even reduce it.     

Strain differences in susceptibility of female mice to 1,2-dimethylhydrazine

C3H, CBA, C57BL/6j, (CBA x C57BL/6j)F1, BALB/c, DBA/2, C3HA and AKR female mice were treated with 25 weekly s.c. injections of a solution of 1,2-dimethylhydrazine (DMH) in water at a dose level of 8 mg/kg body weight. BALB/c mice appeared to be most sensitive to the induction of epithelial colorectal (93.3%) and anal tumours by DMH. There was, however, a dissociation between the severity of the macroscopical tumour lesions in the colon of BALB/c mice and their relatively weak tendency to infiltrative growth. C3HA mice were more resistant to the induction of intestinal tumours (30.9%) but the tumours showed a deep invasion into the intestinal wall. There was no correlation between the strains and within a given strain between the development of colorectal and anal neoplasms. C3H and CBA mice strains developed a high incidence of uterine sarcomas (37.5 and 40.7%, respectively) which were not found at all in BALB/c, DBA/2 and C3HA mice and which appeared in C57BL/6j and AKR mice at low frequency (2.7 and 7.7%, respectively). C57BL/6j, BALB/c, DBA/2 and C3HA mice developed haemorrhagic lesions of the ovaries (35.1, 46.7, 62.9 and 85.7%, respectively). These lesions, which led to peritoneal haemorrhage, were one of the main causes of death in C3HA and DBA/2 strains. It seems that, with the exception of AKR mice, an inverse relationship exists between the occurrence of haemorrhagic ovarian lesions and development of uterine sarcomas in female mice treated with DMH.     

The effects of morphine on the release of noradrenaline from the mouse vas deferens

Electrical field stimulation of the mouse vas deferens (TO and C57/BL strains) caused the release of noradrenaline into the bathing medium. 2 Phenoxybenzamine (30 muM) or phentolamine (36 muM) plus cocaine (13 muM) caused a considerable increase in the noradrenaline output. 3 In the vasa deferentia from TO mice the output per pulse of noradrenaline was constant at frequencies of stimulation from 0.5 to 15 Hz whereas in the vasa deferentia from C57/BL mice the output per pulse of noradrenaline increased two-fold from 1.5 to 15 Hz. 4 Morphine (2 muM) inhibited the contractions of the vasa deferentia from TO mice. This effect was greater at low (0.1-1 Hz) than at high (10 Hz) frequencies of stimulation. Morphine (2 muM) did not inhibit the response of the tissue to exogenous noradrenaline. 5 Morphine (1 muM) reduced the noradrenaline output from the vasa deferentia of TO mice stimulated at 1.5 Hz but did not reduce the noradrenaline output at 15 Hz. At 1.5 Hz the reduction of noradrenaline output was reversed by naloxone (0.05 muM). 6 Morphine (5 muM) did not inhibit the uptake of [3H]-noradrenaline into the vasa deferentia from TO mice. 7 Only in high concentrations (ID50 30.88 muM) did morphine inhibit the contractions of the vasa deferentia from C57/BL mice. 8 Normorphine (100 muM) did not reduce the noradrenaline output from vasa deferentia of C57/BL mice.     

Hepatic cirrhosis and clearance of fibrinolysis activators]

Strain differences in the antibody response to human IgG (HGG) were observed when aggregated HGG was injected intravenously. Lipopolysaccharide (LPS) administered subsequently markedly enhanced the antibody response to HGG in low responder C57BL/6 mice as compared with that in high responder DDD, C3H/He or (C57BL/6 X DDD)F1 mice. Aggregate-free preparation of HGG at a dose of 0.5 mg induced immunological tolerance in all strains of mice tested. LPS injected subsequently converted tolerogenic, aggregate-free HGG into immunogen in DDD mice but not in C57BL/6 mice. To determine the correlation between adjuvanticity and mitogenicity of LPS, spleen cells from normal mice were cultured in the presence of LPS and 3H-thymidine uptake was measured. Spleen cells of DDD mice incorporated three times as much 3H-thymidine as those of C57BL/6 mice. There seems no strong correlation between both activities of LPS. The data obtained are discussed in terms of strain differences in the macrophage function for processing the antigen.     

Suppression of skin reactivity to purified protein derivative by hepatitis C virus among HTLV-I carriers in Japan

Gamma-aminobutyric acid (GABA)A receptors are the sites of action for many antiepileptic drugs such as benzodiazepines and barbiturates. We report the results of molecular cloning of the gamma1-subunit from seizure prone DBA/2J and resistant C57BL/6J inbred mice, and analyses of nucleotide sequences and expression of the gamma1-subunit messenger RNA (mRNA) in DBA/2 and C57BL/6 inbred mice. The mouse gamma1-subunit complementary DNA (cDNA) shares 98% similarity with that of the rat at the level of amino acid sequence. Northern blot hybridization indicates that the gamma1-subunit mRNA is expressed predominantly in areas other than the cerebral cortex and cerebellum and shows little change with postnatal development. No differences have been found for the subunit between DBA/2 and C57BL/6 mice either for nucleotide sequence or for level of expression of the subunit's mRNA in whole brain by Northern blots at 3 weeks of age.