Antigenic properties of T cell antigen-specific receptors isolated from the surface of rabbit and mouse spleen and lymph node cells

The presence ofa allotypic determinants was tested in fractions obtained by gel filtration of antigen-specific receptors isolated by immunoadsorption from lymphoid cells of antigen-stimulateda3-3 rabbits. This technique, as well as the inhibition of the reaction of isolated receptors with anti-T cell receptor antisera (anti R) by anti-a3 antibodies failed to demonstrate the presence of a allotypie determinants. The inhibitory effect of antigen-specific receptors isolated from the lymphoid cells of stimulated A/J mice on the cytotoxic effect of anti-Ia antibodies on mouse spleen cells in the presence of rabbit complement was tested. All preparations inhibited the cytotoxic reaction with the average effectivity of 60%. In order to confirm the presence of Ia determinants on the rabbit and mouse T cell receptor molecules it was shown that the reactions of three anti-R antisera with 12 different receptor preparations were inhibited by anti-la antibodies. SDS-PAGE analyses of¹²⁵I-labelled mouse specific receptors and the precipitate obtained by anti-R antisera showed that T cell receptors were present in fractions with molar mass 100 and 85 kg/mol. The molar mass of the former fraction after reduction and alkylation was 45 kg/mol.     

Evidence for the presence of specific binding sites for corticoids in mouse liver plasma membranes

Summary The specific binding of [³H]cortisol to plasma membranes purified from mouse liver, studied by the ultrafiltration method, shows the existence of specific binding sites for cortisol. The kinetic parameters of this binding areK _D=4.4nm andB _max=685 fmol/mg protein in presence of 1 m of corticosterone. With respect to the binding of 4nm [³H]cortisol to the membrane, the affinities of the steroids decreased in the following order: deoxycorticosterone>corticosterone>progesterone>cortisol >prednisolone>testosterone>20-hydroxyprogesterone >cortisone. Estradiol, dexamethasone, ouabain and triamcinolone acetonide do not have affinity for this binding site. Neither Ca²⁺ nor Mg²⁺ affected the binding of [³H]cortisol to the plasma membranes. Likewise, the presence of agonists and antagonists of alpha and beta-adrenergic receptors did not modify the binding of [³H]cortisol. The results suggest that the plasma membrane binding site characterized is more specific for corticoids and is different from nuclear glucocorticoid and progesterone receptors.     

Murine glucocorticoid receptors and the H-2 locus--a reappraisal

It has been demonstrated that susceptibility to glucocorticoid-induced formation of cleft palate is regulated by the mouse histocompatibility complex (H-2). This has encouraged us to examine H-2 effects on glucocorticoid binding in tissues of adult animals which would provide sufficient material with which to study the biochemical mechanism of the H-2 effect. Although it has been reported that cytosol prepared from lungs of adult mice with a high susceptibility to steroid-induced cleft palate formation have a higher level of glucocorticoid binding than lung cytosol prepared from a low-susceptibility strain, we are unable to demonstrate any influence of H-2 on binding capacity in this tissue from adult animals when glucocorticoid receptors are assayed in the presence of receptor reducing and stabilizing agents that maximize binding capacity. Cytosol prepared from rat liver contains an endogenous receptor-reducing system composed of NADPH and thioredoxin. It has also been reported that the murine H-2 complex contains a gene(s) that regulates the level of a modifier(s) in fetal hepatic cytosol that affects the binding of glucocorticoids to the receptor. Of two known low molecular weight modifiers that could account for this effect, we have previously established that the heat-stable, steroid receptor "modulator" is not regulated by the H-2 complex. In the present work we have assayed thioredoxin, a second potential modifier, in liver cytosols prepared from adults of two pairs of two H-2 congenic mouse strains. Our results show that the amount of thioredoxin is the same in all four mouse strains and that it is not regulated by the H-2 locus. At this time, we are unable to identify a system in adult mice in which the widely reported regulation of glucocorticoid binding by the mouse histocompatibility locus can be submitted to definitive biochemical study.     

Receptor binding of 6 alpha-methylprogesterone in mouse kidney

6 alpha-Methylprogesterone (6MP) is an androgenic progestin that binds to the androgen receptor. However, results from an in vivo study suggested that 6MP was also bound by a second receptor. In the present study, we found that 6MP was bound in kidney cytosol from adrenalectomized/ovariectomized female mice as well as Tfm/Y mice, which lack androgen receptors. 6MP was bound with high affinity (Kd = 1.2 X 10(-8) M) by a binder that was present in 7-8 times greater concentration than the androgen receptor and had the specificity of a glucocorticoid receptor. 6MP was bound with similar specificity in liver cytosol. These data indicate that, despite its androgenic effects, 6MP binds primarily to a glucocorticoid receptor in mouse kidney.     

Effects of opioid peptides on the cellular immunity in spleen cells from intact nude mice or nude mice bearing human ovarian carcinoma

Summary The present study was designed to explore the effects of opioid peptides on the lytic activity of spleen cells from intact nude mice or nude mice bearing human ovarian cancer cells (KF). When the spleen cells from intact nude mice were incubated with various concentrations of opioid peptides, the ability of the spleen cells to lyse the KF cells was significantly stimulated between 0.05 nM and 50 nM concentrations of all opioid peptides used in this study. The degree of stimulation was most marked at 5 nM opioid peptides and the most marked stimulatory effect was obtained by -endorphin. On the other hand, the lytic activity of spleen cells from nude mice challenged with the KF cells was about two-fold higher than that of intact nude mice, suggesting that spleen cells from nude mice challenged with KF cells have KF-cell-specific cytotoxicity. Even if the spleen cells were incubated with any concentration of -endorphin or [Met]enkephalin indicated, the lytic activity remained unchanged. In contrast, only -endorphin resulted in a significant increase of the lytic activity between 0.5 nM and 50 nM. These results suggest that opioid peptides play a crucial role in immune surveillance mechanisms.     

Neo-epitopes emerging in the degenerative hippocampal granules of aged mice can be recognized by natural IgM auto-antibodies

Background

Degenerative granular structures appear progressively with age in the hippocampus of most mouse strains. We recently reported that these granules contain a neo-epitope that is recognised by IgM antibodies present as contaminants in many commercial antibodies obtained from mouse ascites and mouse or rabbit serum. We hypothesise that these anti-neo-epitope IgMs are in fact natural auto-antibodies that are generated spontaneously during the foetal stage without previous contact with external antigens and whose repertoire and reactivity pattern have been determined through evolution, being remarkably stable within species and even between species.

Findings

In the present work we found that mice from the ICR-CD1, BALB/C and SAMP8 strains have anti-neo-epitope IgM antibodies in their plasma at all ages tested and even when maintained under specific opportunistic pathogen-free conditions. Moreover, we determined that these anti-neo-epitope IgMs are also present in rabbit, goat and rat serum. We also found that, in each mouse that presented hippocampal granules, the anti-neo-epitope IgMs contained in its plasma recognised the neo-epitopes in its own granules.

Conclusions

This study led to the conclusion that anti-neo-epitope IgMs are widespread natural auto-antibodies contained in the plasma of mice and other species. The presence of these natural auto-antibodies not only explains why they are frequently found as contaminants in commercial antibodies, but also paves the way for a new approach to a treatment and diagnosis of pathological brain processes based on natural IgMs and neo-epitopes.

     

The Effect of Losing Glycosylation Sites Near the Receptor-Binding Region on the Receptor Phenotype of the Human Influenza Virus H1N1

The receptor properties of influenza virus A/USSR/90/77 isolates are studied. The isolates are peculiar for losing glycosylation sites at the Asn131 receptor-binding region (GS131) after passaging in mice and at the Asn158 region (GS158) after cultivation in the presence of mouse serum. The loss of each carbohydrate residue increases the influenza virus affinity for carbohydrate chains with the terminal group Neu5Ac2-6Gal and reduces its affinity for Neu5Ac2-3Gal receptors. The effect is more pronounced in the GS158-depleted virus. Upon substitution of asparagine by aspartic acid, the electrostatic component of virus binding to the receptor is altered because of the increased negative charge on hemagglutinin. The virus receptor phenotype changes depending on the cultivation conditions. The isolate adapted to mice has higher affinity to mouse lung cell receptors, while the virus propagated in chick embryos in the presence of inhibitors has higher affinity to allantoic membrane cells.     

Immunotherapy of metastases of human neoplastic cells grown in immunodeficient mice

Summary Hereditarily athymic (nude) and asplenic-athymic (lasat) mice were inoculated neonatally with 10⁷ K-562 pluripotential leukemia cells of human origin. Meningeal infiltration and/or multiple metastases were found in the lungs, kidneys, and lymph nodes in nearly 60% of mice. Twice as many lasat mice as nude mice had meningeal and lymph node infiltrations. This result indicates that the spleen of nude mice influences the infiltrations and/or the distribution of metastases. Metastases of K-562 cells were found as early as 10 days and as late as 115 days of age. Goat immune gamma ()-globulin, prepared from antiserum to K-562 cells and absorbed with peripheral leukocytes and bone marrow cells from normal individuals, markedly diminished the incidence of metastases of K-562 cells. About 16% of the mice treated with immune -globulin had metastases in the lungs only. All mice receiving the immune -globulin had peripheral monocytosis and lymphocytosis as well as a hyperplasia of the bone marrow monocytic series. Immune -globulin may lyse heterotransplanted leukemia cells by direct binding to leukemia cells in the presence of complement and/or may activate antibody-dependent effector cells, for example macrophages or killer cells, which would destroy the transplanted leukemia cells.     

A relationship between circulating natural glucocorticoids and the mechanical responses of the heart in atricial and precocial rodents

• 1.1. A comparison was made of the mechanical performance of heart muscle from mouse, an atricial mammal, with corticosterone as glucocorticoid and spiny mouse (Acomys cahirinus), a precocial mammal, with cortisol as glucocorticoid.
• 2.2. Force-frequency responses were negative in mouse and positive in spiny mouse.
• 3.3. During recovery, there was a gradual increase and an overshoot in the mouse, while in the spiny mouse there was an initial enhanced response, diminishing gradually with time.
• 4.4. High calcium concentration inhibited contractile tension in mouse heart, while it was positively inotropic in spiny mouse heart. Changes in the concentration of calcium did not change the patterns of force-frequency response.
• 5.5. Lowering the experimental temperature increased the time course and amplitude of the tension curve. However, various parameters exhibited different temperature sensitivity.
• 6.6. There was a significant difference in the levels of circulating cortisol between male and female spiny mice.
• 7.7. It is proposed that the differences in the mechanical responses of mouse and spiny mouse hearts may be explained in terms of the effects of the specific glucocorticoid hormone on the development of the sodium-calcium exchanger.

     

Cross-reactivity of a monoclonal antiglucocorticoid receptor antibody BuGR1 with glucocorticoid and mineralocorticoid receptors of various species

The reactivity of a monoclonal antibody BuGR1, raised against glucocorticoid receptors of rat liver, with glucocorticoid and mineralocorticoid receptors of mammalian (rabbit) and amphibian (A6 cells) origin was examined. The glucocorticoid receptors of rabbit kidney and liver and of A6 cells were labeled with tritiated dexamethasone. The mineralocorticoid receptors were labeled with tritiated aldosterone in the presence or absence of RU26988, depending on whether aldosterone was bound to glucocorticoid receptors (A6 cells) or not (rabbit kidney), in addition to its binding to mineralocorticoid receptors. BuGR1 did not recognize mineralocorticoid receptors of A6 cells and rabbit kidney. BuGR1 cross-reacted with glucocorticoid receptors of rabbit liver and kidney but not of A6 cells, suggesting that the domain of glucocorticoid receptors recognized by BuRG1 could be present only in the mammalian species. The findings indicate that BuGR1 shows species differences as well as receptor class specificity.     

Control of liver tyrosine aminotransferase expression: Enzyme regulatory studies on inbred strains and mutant mice

Studies on the genetic mechanisms in control of mouse liver tyrosine aminotransferase expression were of three general types: (1) studies on strain variance in endogenous enzyme activity and of various factors affecting the basal enzyme level, (2) purification of the enzyme and studies of its properties, and (3) studies of strain variance in enzyme regulation dealing primarily with glucocorticoid induction and with the starvation-induced enzyme adaptation. Tyrosine aminotransferase (l-tyrosine: 2-oxoglutarate aminotransferase, E.C. 2.6.1.5) was purified 400 to 600-fold from livers of C57BL/6J and DBA/2J inbred mice. Several of the properties of the mouse liver enzyme were similar to those known for the rat liver enzyme although the apparent K _m (l-tyrosine) was lower, calculated at 6.25×10^–4 M. Disc gel electrophoresis of the enzyme from 105,000 g supernatant fluid after induction by hydrocortisone indicated three bands of enzyme activity with strain variance in electrophoretic mobility between the C57BL/6J and DBA/2J mice. The administration of glucose to fasting C57BL/6J mice repressed the starvation-induced increase in enzyme activity, but did not prevent the hydrocortisone induction of enzyme activity. DEAE-cellulose chromatography of purified enzyme from fasting DBA/2J and C57BL/6J mice which had been labeled in vivo with C ¹⁴ -l-leucine revealed strain differences in the elution patterns for both enzyme activity and radioactivity. Two peaks of enzyme activity were detected in the enzyme preparations from fasting mice. The marked strain variance in the enzyme activity and the quantity of radioactivity associated with the first enzyme peak may indicate differential rates of protein turnover for different isozymic forms of tyrosine aminotransferase. Flumethasone, a potent difluoro synthetic glucocorticoid, was used in studies on the hormonal regulation of tyrosine aminotransferase in obese mutant mice of the C57BL/6J-ob strain. The obese mice are relatively insensitive to the action of adrenal glucocorticoids to cause liver enzyme induction.This paper was presented at a symposium entitled Genetic Control of Mammalian Metabolism held at The Jackson Laboratory, Bar Harbor, Maine, June 30–July 2, 1969. The symposium was supported in part by an allocation from NIH General Research Support Grant FR 05545 from the Division of Research Resources to The Jackson Laboratory.This investigation was supported in part by an allocation from the NIH General Research Support Grant FR 05545 from the Division of Research Resources to The Jackson Laboratory and in part by Institutional Grant IN-19 from the American Cancer Society to The Jackson Laboratory.     

Characterization of the Ah receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin: use of chemical crosslinking and a monoclonal antibody directed against a 59-kDa protein associated with steroid receptors

The Ah receptor regulates induction of cytochrome P450IA1 (aryl hydrocarbon hydroxylase) by "3-methylcholanthrene-type" compounds and mediates the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and related halogenated aromatic hydrocarbons. Hepatic Ah receptor from untreated rodents is localized in the cytosol and has an apparent molecular mass of 250 to 300 kDa. This large form can be dissociated into a smaller ligand-binding subunit upon exposure to high ionic strength. The Ah receptor displays many structural similarities to the receptors for steroid hormones. Two non-ligand-binding proteins have been identified to be associated with the cytosolic forms of the steroid hormone receptors. The first is a 90-kDa heat shock protein (hsp 90); the second is a 59-kDa protein (p59) of unknown function. The cytosolic Ah receptor ligand-binding subunit previously has been shown to be associated with hsp 90. In the present study, we used a monoclonal antibody, KN 382/EC1, generated against the 59-kDa protein which is associated with rabbit steroid receptors to determine if p59 also is a component of the large cytosolic Ah receptor complex. Cytosolic forms of rabbit progesterone receptor, glucocorticoid receptor, and Ah receptor were analyzed by velocity sedimentation on sucrose gradients under low-ionic-strength conditions and in the presence of molybdate. Progesterone receptor from rabbit uterine cytosol and glucocorticoid receptor from rabbit liver each had a sedimentation coefficient of approximately 9 S. In the presence of KN 382/EC1 antibody the progesterone receptor and the glucocorticoid receptor both underwent a shift in sedimentation to a value of approximately 11 S. The increase in sedimentation velocity is an indication that the receptor-protein complexes are interacting with the antibody. Under low-ionic-strength conditions the Ah receptors from rabbit uterine cytosol and liver cytosol had a sedimentation coefficient of approximately 9 S. However, in contrast to the steroid receptors, the Ah receptor showed no change in its sedimentation properties in either tissue in the presence of KN 382/EC1, indicating that the antibody is not interacting with the Ah receptor. Multimeric Ah receptor complexes that were chemically crosslinked still did not show any interaction with KN 382/EC1. These data indicate that the 59-kDa protein either is not associated with the Ah receptor or is present in an altered form which the antibody cannot recognize.     

Pharmacokinetics of radioiodinated human and ovine growth hormones in transgenic mice expressing bovine growth hormone

Pharmacokinetics of radioiodinated human growth hormone (hGH) and ovine growth hormone (oGH) were studied in normal mice and in transgenic mice carrying the bovine growth hormone (bGH) gene fused to phosphoenolpyruvate carboxykinase promoter/regulator (PEPCK-bGH). Multiexponential plasma decay curves were obtained in both normal and transgenic mice after a¹²⁵I-oGH injection and pharmacokinetic parameters were estimated by fitting blood concentration data to a three compartment model. The half-life for the rapid compartment was shorter in transgenic than in normal mice (t_1/2:1.2±0.3 vs. 2.2±0.5 min). The slow compartment had a t_1/2 of 160±23 min for transgenic and 70±8 min for normal mice while the middle compartment had a t_1/2 of approximately 10 min for both groups of mice. The mean residence times were 167±24 and 55±5 min for transgenic and normal mice, respectively. Specific liver uptake of radioactivity after injection of¹²⁵I-oGH or¹²⁵I-hGH was found in both groups of animals. Specificity studies indicated that, similarly to normal mice, livers of transgenic mice possess a mixed population of somatotropic and lactogenic receptors. Uptake of labelled hGH by the liver was dose-dependent and the doses that prevented 50% of liver uptake (ED_50%) were 8 and 165 g per 50 g body weight for normal and transgenic mice, respectively. Thesein vivo results confirm and extend previousin vitro findings that a life-long excess of bGH increases hepatic somatotropic and lactogenic receptors. Since elevation in growth hormone (GH) receptors was reported to be associated with an increase in GH binding protein (GHBP), we suspect that both the increase in the mean residence time and the reduction in specific uptake of GH in the livers of transgenic mice may be the result of an increase in GHBP levels.     

The cytogenetic and hepatotoxic effects of dioxin on mouse liver cells

The cytogenetic and hepatotoxic effects of 2,3,7,8-tetrachlorodibenzo p-dioxin (TCDD) on mouse liver cells were investigated. Male C57BL/6J strain mice, which have TCDD receptors, were given single intraperitoneal injections of 25, 37.5, 75 and 150 g of TCDD/kg body weight or corn oil carrier alone. Two-thirds hepatectomies were carried out at 1 or 7 days after injection and chromosomal aberrations and mitotic indexes of the regenerating hepatocytes were scored 54 hr after hepatectomy. Liver sections from additional intact mice were studied for TCDD-hepatotoxicity at 1, 7 and 30 days after injection. The three high doses of TCDD caused hepatotoxicity with necrosis of liver cells and focal architectural collapse by 30 days after injection. No evidence was obtained of an increase in the frequency of chromosomal structural aberrations at doses that allowed sufficient mitotic activity for cytogenetic evaluation. We conclude that TCDD is not a clastogen for mouse hepatocytes, although high doses cause marked hepatocellular necrosis.Abbreviations CSD chromosome deletion - META metacentric chromosome - TCDD 2,3,7,8-tetrachlorobenzo-p-dioxin     

Ineffectiveness of the presence of H-ras/p53 combination of mutations in squamous cell carcinoma cells to induce a conversion of a nontumorigenic to a tumorigenic phenotype

Human tumor cells have properties in vitro or in surrogate hosts that are distinct from those of normal cells, such as immortality, anchorage independence, and tumor formation in nude mice. However, different cells from individual tumors may exhibit some, but not all of these features. In previous years, human tumor cell lines derived from different tumor and tissue types have been studied to determine those molecular changes that are associated with the in vitro properties listed above and with tumorigenicity in nude mice. In the present study, seven cell lines derived from human tumors were characterized for p53 and ras mutations that may occur in SCC tumor phenotypes and for tumor formation in nude mice. This investigation was designed to examine whether co-occurrence of mutated ras and p53 lead to a malignant stage in the progression process. None of the seven cell lines contained mutations in the recognized "hot spots" of the p53 tumor suppressor gene, but four had a nonsense/splice mutation in codon 126 and a mutation in codon 12 of the H-ras gene. The remaining three cell lines had p53 mutations in intron 5, in codon 193, and a missense mutation in codon 126, respectively. Four of seven cell lines were nontumorigenic; two of these cell lines contained a nonsense p53-126 mutation and mutated ras; one had a missense mutation at codon 126 but no mutated ras; the the fourth had only a p53 mutation at codon 193. Two of the nontumorigenic cell lines were converted to tumorigenicity after treatment with methyl methanesulfonate or N-methyl-N-nitro-N-nitrosoguanidine with no apparent additional mutations in either gene. Our analysis revealed that there was a high frequency of genetic diversity and mutations in both p53 and H-ras. There was also a lack of a causal relationship in the presence of mutations in p53 and the cells ability to exhibit a malignant potential in nude mice.     

Development and Characterization of a Mouse Model for Marburg Hemorrhagic Fever

The lack of a mouse model has hampered an understanding of the pathogenesis and immunity of Marburg hemorrhagic fever (MHF), the disease caused by marburgvirus (MARV), and has created a bottleneck in the development of antiviral therapeutics. Primary isolates of the filoviruses, i.e., ebolavirus (EBOV) and MARV, are not lethal to immunocompetent adult mice. Previously, pathological, virologic, and immunologic evaluation of a mouse-adapted EBOV, developed by sequential passages in suckling mice, identified many similarities between this model and EBOV infections in nonhuman primates. We recently demonstrated that serially passaging virus recovered from the liver homogenates of MARV-infected immunodeficient (SCID) mice was highly successful in reducing the time to death in these mice from 50 to 70 days to 7 to 10 days after challenge with the isolate MARV-Ci67, -Musoke, or -Ravn. In this study, we extended our findings to show that further sequential passages of MARV-Ravn in immunocompetent mice caused the MARV to kill BALB/c mice. Serial sampling studies to characterize the pathology of mouse-adapted MARV-Ravn revealed that this model is similar to the guinea pig and nonhuman primate MHF models. Infection of BALB/c mice with mouse-adapted MARV-Ravn caused uncontrolled viremia and high viral titers in the liver, spleen, lymph node, and other organs; profound lymphopenia; destruction of lymphocytes within the spleen and lymph nodes; and marked liver damage and thrombocytopenia. Sequencing the mouse-adapted MARV-Ravn strain revealed differences in 16 predicted amino acids from the progenitor virus, although the exact changes required for adaptation are unclear at this time. This mouse-adapted MARV strain can now be used to develop and evaluate novel vaccines and therapeutics and may also help to provide a better understanding of the virulence factors associated with MARV.The filoviruses, Marburgvirus and Ebolavirus (MARV and EBOV), cause severe hemorrhagic fevers in humans and nonhuman primates (27). The incubation time is estimated to be 3 to 21 days, with human case fatality rates reaching 90% in some outbreaks. Filoviral hemorrhagic fevers are characterized by a nonspecific viral prodrome in the early stage of infection, including fever, headaches, and myalgia (27). This is followed by a hemorrhagic phase that can include development of a maculopapular rash, petechiae, and bleeding from the gums, intestines, and other mucosal surfaces. Death usually occurs within a week of initial symptoms and is thought to be due to uncontrolled viral replication, hypotension-induced shock caused by increased vascular permeability, and multiorgan failure, likely caused by disseminated intravascular coagulation and extensive necroses in the liver, spleen, intestine, and many other major organ systems (27).Human-derived MARVs (isolates Angola, Musoke, Ravn, and Ci67) do not kill immunocompetent adult mice (23). Furthermore, there are no published reports of any lethal mouse-adapted MARV. The current mouse-adapted EBOV, strain Zaire (ZEBOV), was developed by performing nine sequential passages of ZEBOV 1976 virus in suckling mice, followed by two sequential plaque picks. The resulting virus was uniformly lethal to mice inoculated intraperitoneally (i.p.). Pathological evaluation of infected mice identified many similarities and only a few differences between this model (7, 22) and infections in nonhuman primates (21).In a previous study, we took a slightly different approach to mouse adaptation of MARV and found that serially passaging virus recovered from the liver homogenates of MARV-Ravn-infected adult mice with severe combined immunodeficiency (SCID mice) resulted in the generation of SCID-adapted MARV-Ravn (scid-MARV) that rapidly killed SCID mice but did not kill adult immunocompetent mice (51). In this study, we used scid-MARV as starting material for the first round of infection of adult immunocompetent BALB/c mice and serially passaged virus recovered from the liver homogenates of the BALB/c mice. MARV-Ravn was chosen over SCID-adapted MARV-Ci67 or -Musoke because it adapted more rapidly to SCID mice than the other isolates did. This produced a mouse-adapted MARV-Ravn strain (ma-MARV) that could kill adult BALB/c mice. Serial sampling studies to characterize the pathogenesis of ma-MARV revealed that this model was very similar to the guinea pig and nonhuman primate Marburg hemorrhagic fever (MHF) models, including rapid viremia, induction of D-dimers (fibrin degradation products), thrombocytopenia, profound loss of circulating and tissue lymphocytes, and marked liver damage. Additionally, we compared the immunological responses of mice after infection with either nonadapted wild-type MARV-Ravn (wt-MARV) or ma-MARV. This mouse model of MARV infection not only should advance our understanding of MARV pathogenesis and immunity but also may play a critical role in discovery of therapeutics for MARV infection.     

Reproductive defects in the male diabetic athymic nude mouse

We have previously reported spontaneous hyperglycemia and impaired glucose tolerance in male athymic nude Balb/c mice. This colony also demonstrates impaired fertility. Previous studies in both athymic nude and diabetic obese (ob/ob) mice have shown reproductive abnormalities. It was the purpose of this investigation to further elucidate the endocrine abnormalities which might contribute to the reduced fertility observed in this model. Fasting plasma glucose was measured on each nude mouse to ensure that a diabetic state existed. Testes were removed and intratesticular testosterone and LH receptors were measured. Testosterone levels in diabetic, athymic nude Balb/c (DAN) mice were significantly decreased to 46.5% of control Balb/c mice. LH receptors in DAN mice were significantly elevated by 23.6% when compared to control animals. These results demonstrate that the impaired fertility observed in the DAN mouse may result from decreased testosterone production. The increased LH receptor levels seen in the DAN mouse might reflect a regulatory event in response to the decreased intratesticular testosterone levels.     

人卵巢癌裸鼠移植实体瘤模型的建立

目的建立人卵巢癌裸鼠移植实体瘤模型。方法将1例人卵巢癌组织移植裸鼠,建立人卵巢癌裸鼠原代移植实体瘤模型的基础上,再将实体瘤皮下移植、实体瘤原位移植、实体瘤细胞移植裸鼠。观察裸鼠实体瘤生长和转移情况,称量其体重、子宫卵巢重、瘤重及瘤的大小,并作病理、电镜、染色体检查。结果成功地建立人卵巢癌裸鼠移植实体瘤模型,并已传至第18代,传代移植成功率100％,组织学和超微结构形态均证明该实体瘤保留了原人卵巢癌特征,有人卵巢癌染色体特征,并出现肝、脾转移。结论本研究建立人卵巢癌裸鼠移植实体瘤模型与人相似,通过18代传代和实验观察方法稳定可靠。为人卵巢癌的研究提供了理想的动物模型。     

Localization of type 5 17β-hydroxysteroid dehydrogenase mRNA in mouse tissues as studied by in situ hybridization

The mouse enzyme type 5 17-hydroxysteroid dehydrogenase (17-HSD) catalyzes the conversion of androstenedione to testosterone and, to a lesser degree, the conversion of estrone to estradiol. In order to determine the exact sites of action of type 5 17-HSD, we studied the cellular localization of the mRNA of the enzyme in mouse tissues by using in situ hybridization. Specific hybridization signal was found in the liver, ovary, adrenal cortex, and kidney. In the liver of mice of both sexes, a strong signal was observed in all hepatocytes. In the ovary, specific labeling was detected in the granulosa and theca interna cells in growing follicles and in luteal cells. In the female adrenal cortex, intense labeling was restricted to the zona reticularis, whereas no type 5 17-HSD mRNA expression could be found in the male adrenal cortex. In the kidney of mice of both sexes, type 5 17-HSD mRNA was expressed in epithelial cells in both the proximal and distal convoluted tubules. The data indicate that androgens and estrogens are formed via the action of type 5 17-HSD in specific cell types in the liver, ovary, adrenal cortex, and kidney.This work was supported by Genome Canada and Genome Québec.