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the hepatitis b virus and its dna polymerase: the prototype three-d virus.the hepatitis b virus (hbv), the causal agent of serum hepatitis, has a diameter of 42 nm and is comprised of an outer surface coat and a 27 nm core. a unique dna-dependent dna polymerase is associated with the core of the virus. the core also houses a circular dna that contains both double-stranded and single-stranded regions. in the endogenous reaction, the dna polymerase repairs the single-stranded gaps of the viral dna. the surface protein of the virus, called hepatitis b surface antigen, co ...197991092
seasonal variation and the influence of body temperature on plasma concentrations and binding of thyroxine and triiodothyronine in the woodchuck.woodchuck plasma was collected during four seasons of the year and assayed for total and dialyzable (free) t4 and t3 and for rt3. plasma concentrations of total and free t4 and t3 were higher in the spring (t4, 5.4 +/- 0.6 microgram/dl; free t4, 3.0 +/- 0.4 ng/dl; t3, 202 +/- 22 ng/dl; free t3, 0.51 +/- 0.04 ng/dl) and lower in the prehibernatory fattening period in summer (t4, 2.3 +/- 1.0 microgram/dl; free t4, 1.2 +/- 0.5 ng/dl; t3, 45 +/- 27 ng/dl; free t3, 0.16 +/- 0.10 ng/dl) and fall (t4, ...1979108089
structural and functional comparison of myosin from the rabbit oryctolagus cuniculus and the marmot marmota monax. 1975124642
serologic evidence of leptospirosis in woodchucks (marmota monax) in central new york state.serum samples from 153 woodchucks (marmota monax) from tompkins county, new york, obtained in 1976 and 1977, were examined by plate agglutination tests for antibodies against five leptospira antigens. fourteen sera showed significant titers against either l. hardjo, l. icterohemorrhagiae and/or l. pomona. reactions against l. hardjo were the most frequent. woodchucks collected from two dairy farms with histories of bovine leptospirosis did not have a greater prevalence of antibodies than woodchu ...1979480515
hibernation and circannual rhythms of food consumption in marmots and ground squirrels.in order to understand better the evolution and adaptive value of hibernation, ecological aspects and experimental studies of closely related hibernators, the marmotini, are examined. the central hypothesis is that annual changes in the environment integrate three or, perhaps, four physiological processes: torpor, reporduction, consumption of food, and metabolism. reproduction occurs promptly after emergence from hibernation. for most species, the breeding season is very short. although the expe ...1976799318
selenium and white muscle disease in woodchucks.gross and histologic examination of wood chcks (marmota monax) trapped on farms in central new york revealed white muscle disease(wmd). the concentration of selenium in the animal tissues, vegetation and soils in the vicinity of trapping did not consistently correlate with the presence of wmd.1977916140
capillaria hepatica in a groundhog (marmota monax). 19751113432
expression of insulin-like growth factor ii (igf-ii) and igf-ii, igf-i and insulin receptors mrnas in isolated non-parenchymal rat liver cells.the insulin-like growth factor ii (igf-ii) is involved in embryonic growth. modifications of its expression might play a role in the development of primary liver cancer in humans and woodchucks. in the liver, little information is available on the cell types involved in its synthesis. we have investigated the expression of igf-ii as well as igf-ii, igf-i and insulin receptor mrnas in non parenchymal liver cell preparations in rats of various ages. the results indicate that kupffer cells, endothe ...19921310705
serological relationship of woodchuck hepatitis virus to human hepatitis b virus.two antigenic systems of the woodchuck hepatitis virus have been identified. the relationship between viral antigens of the woodchuck hepatitis virus and the human hepatitis b virus was determined by using immunoprecipitation, hemagglutination, and immune electron microscopy techniques. antigens found on the cores of the two viruses were cross-reactive. lack of cross-reactivity between the surface antigens of the two viruses in immunodiffusion experiments suggested that the major antigenic deter ...197994359
the role of hepatitis b virus in the development of primary hepatocellular carcinoma: part i.chronic infections with hepatitis b virus (hbv) of humans and animal hepadnavirus infections in their natural hosts are strongly associated with primary hepatocellular carcinoma (hcc). although viral integrations are found in cells of many hcc, no general viral-specific hepatocarcinogenic mechanism for hepadnaviruses has been identified. in approximately one half of hcc in woodchuck hepatitis virus (whv) infected woodchucks, viral integrations near the c-myc or n-myc genes have been reported whi ...19921336678
expression of the woodchuck n-myc2 retroposon in brain and in liver tumors is driven by a cryptic n-myc promoter.the woodchuck intronless proto-oncogene n-myc2 was initially discovered as a frequent target site for hepadnavirus integration in hepatocellular carcinoma. n-myc2 possesses characteristics of a functional retroposon derived from the woodchuck n-myc gene. we have investigated the regulatory signals governing n-myc2 expression and found that a short promoter, including a variant tata box and potential binding sites for several transcription factors, is localized in the n-myc2 sequences homologous ...19921333041
altered glycosylation of alpha-fetoprotein in hepadnavirus-induced hepatocellular carcinoma of the woodchuck.altered glycosylation of alpha-fetoprotein (afp) has been proposed as a marker of hepatocellular carcinoma (hcc) in humans. the lectin-binding properties of woodchuck afp were investigated to determine if woodchuck hepatitis virus (whv)-induced hccs are also accompanied by changes in afp glycosylation. ninety-eight to 100% of the afp from normal, whv-free woodchucks with physiologic afp elevations and from whv-carrier woodchucks with hcc bound to concanavalin a, indicating that virtually all of ...19921373341
hepadnavirus integration: mechanisms of activation of the n-myc2 retrotransposon in woodchuck liver tumors.in persistent hepadnavirus infections, a distinctive feature of woodchuck hepatitis virus (whv) is the coupling of frequent viral integrations into myc family genes with the rapid onset of primary liver tumors. we have investigated the patterns of whv dna insertion into n-myc2, a newly identified retroposed oncogene, in woodchuck hepatomas resulting from either natural or experimental infections. in both cases, integrated viral sequences were preferentially associated with the n-myc2 locus. in m ...19921323693
multiple rearrangements and activated expression of c-myc induced by woodchuck hepatitis virus integration in a primary liver tumour.woodchuck hepatitis virus (whv) is a small, partially double-stranded dna virus. like the related human hepatitis b virus (hbv), whv induces acute and chronic hepatitis and hepatocellular carcinoma (hcc) in its natural host. whv dna integration into c-myc and n-myc, resulting in deregulated expression of these genes, has been described previously in woodchuck hcc. we have analysed a woodchuck liver tumour in which whv dna was integrated in the c-myc gene. the virus insertion provoked multiple al ...19921317604
permanent outdoor housing for woodchucks, marmota monax.permanent outdoor housing for woodchucks (marmota monax) was constructed from chain link fencing sections on a concrete base. metal poultry nest boxes were attached to 1 side of the cage. each enclosure accommodated up to 10 woodchucks and provided adequate shelter and exercise space. this housing system was inexpensive to construct and efficient to service.1976940301
daily activity and body temperature of the southern woodchuck, marmota monax monax, in northwestern arkansas. 1976932569
the thyroid gland of the woodchuck, marmota monax: a morphological study of seasonal variations in the follicular cells.the morphology of the thyroid gland of the woodchuck, marmota monax, was studied during the four seasons of the year. in the spring the thyroid is extremely heterogenous in appearance. some follicular cells appear quite active. they contain a well defined golgi apparatus, abundant large colloid droplets and pseudopodia but few, if any, apical vesicles. other less active cells have poorly defined rough surfaced endoplasmic reticulum and lack a well developed golgi apparatus. they do not contain a ...1977848781
isolation of a hibernation inducing trigger(s) from the plasma of hibernating woodchucks.plasma from hibernating woodchucks was desalted utilizing a hollow fiber device having a m. w. cut-off of 5,000. this preparation was fractionated by isoelectric focusing (ief) in a ph gradient extending from 3.5 to 10.0 resulting in protein components having isoelectric points (pis) of 4.5, 5.2, 5.5, 6.3, and 7.0. fraction i (comprised of proteins having pis of 4.5 and 5.2) induced hibernation within 2 to 6 days in 8 out of 10 summer-active ground squirrels. fraction ii (pi 5.5) and fraction ii ...1978568785
selenium in tissues of woodchucks inhabiting fly ash landfills. 1979444686
chemosensitivity and breathing pattern regulation of the coatimundi and woodchuck.an analysis of breathing pattern regulation was carried out on the coatimundi and woodchuck who represent two different volume-time patterns. it was found that the coati, with a short expiratory time as a fraction of total breath time, te/ttot, has a greater sensitivity to co2 as represented by the slope and threshold of its ventilatory response. breathing air the coati maintains post-inspiratory inspiratory activity (piia) of the posterior cricoarytenoid (pca) through 51% of expiration, while t ...19921439298
ultrastructure of the apocrine-sebaceous anal scent gland of the woodchuck, marmota monax: evidence for apocrine and mecocrine secretion by a single cell type. 1979426299
intranuclear rodlets in woodchuck thyroid follicular cells.intranuclear rodlets are seen in thyroid follicular cells of woodchucks fixed during summer and fall. they are not observed in winter and spring animals. a functional significance of these structures is suggested.1978215312
serum epoxide hydrolase (preneoplastic antigen) in human and experimental liver injury.reports of an increase in a serum epoxide hydrolase (seh), immunochemically related to microsomal eh in humans and rats with hepatocellular carcinoma (hcc), suggested its use as a serum marker for this disease. we have now measured seh levels (as either immunochemically determined content or enzyme activity) in a number of human and experimental models of liver disease. seh was elevated above the normal range in at least 50% of individuals with hcc, including: 3 of 6 northern californians; 4 of ...19921339049
auditory-evoked brainstem responses in the hibernating woodchuck marmota monax.1. this study measured the changes in the auditory-evoked brainstem responses in the woodchuck (marmota monax) during hibernation and arousal. 2. the auditory brainstem response of the euthermic woodchuck consisted of four waves occurring in a 10 msec time window after stimulation. 3. in the hibernating woodchuck, waves i and ii could be traced down to the lowest body temperatures. 4. as temperatures increased all the components of the abr emerged. the latencies of all the waves showed systemati ...19921359941
mammalian hepatitis b viruses and primary liver cancer.hepatitis b virus is a major etiologic agent in the development of human hepatocellular carcinoma, but the precise role of the virus in the tumorigenic process is still unclear. recent studies of naturally occurring animal models, such as woodchucks and squirrels infected with hepatitis b-like viruses (hepadnaviruses) have revealed different oncogenic strategies and outlined the predominant role of myc genes in rodent hepatomas. higher oncogenicity of woodchuck hepatitis virus has been correlate ...19921335794
viral spliced rna are produced, encapsidated and reverse transcribed during in vivo woodchuck hepatitis virus infection.by the use of reverse transcription followed by polymerase chain reaction (rt-pcr), we have identified one shorter than full-length, pregenomic viral rna species in liver samples of woodchucks chronically infected with the woodchuck hepatitis virus (whv). the spliced whv rna of about 2.4 kb in length was cloned and partially sequenced. the splicing donor and acceptor sites of this novel rna are located, respectively, 130 nucleotides downstream of the atg initiation codon of the core gene and 21 ...19921382340
suppression of guinea pig ileum induced contractility by plasma albumin of hibernators.previous studies suggest that hibernation may be regulated by internal opioids and that the putative "hibernation induction trigger" (hit) may itself be an opioid. this study examined the effect of plasma albumin (known to bind hit) on induced contractility of the guinea pig ileum muscle strip. morphine (400 nm) depressed contractility and 100 nm naloxone restored it. ten milligrams of lyophilized plasma albumin fractions from hibernating ground squirrels, woodchucks, black bears, and polar bear ...19921409805
effects of phyllanthus plant extracts on duck hepatitis b virus in vitro and in vivo.the effects of extracts of five australian phyllanthus species (p. hirtellus, p. gunnii, p. gasstroemii, p. similis and p. tenellus), other plant extracts and the antiviral drug foscarnet on duck hepatitis b virus (dhbv) endogenous dna polymerase (dnap) activity were compared. all 5 phyllanthus species caused 50% inhibition at concentrations of dry weight between 350-800 micrograms/ml, which is comparable with the effect described for p. amarus on the dnap of human and woodchuck hepatitis b viru ...19921416905
direct immunofluorescence testing for immunoglobulin deposits in haired skin, nasal planum and footpads of woodchuck hepatitis virus-infected woodchucks with chronic hepatitis and multiple hepatocellular carcinomas.the purpose of this study was to determine the frequency of immunoglobulin deposition in the haired skin, footpads, and nasal planums of 10 whv-infected woodchucks with chronic hepatitis and hepatocellular carcinoma and compare these results with those reported in humans. immunoglobulin deposition was detected in the skin samples of 3 of 10 woodchucks. granular deposits were revealed in the superficial dermal blood vessels of the nasal planum, lateral thoracic skin, and footpads in 1 animal each ...19921310926
mother woodchuck transports her seven young to new nest. 19751241531
entrainment of circannual rhythm in weight of woodchucks. 19751113040
seasonal variation in the morphology of thyroid parafollicular (c) cells in the woodchuck, marmota monax: a light and electron microscopic study.the morphology of parafollicular (c) cells in the thyroid gland of the woodchuck, marmota monax, was studied during the four seasons of the year. the spring c cells are characterized by a large golgi zone, rough-surfaced endoplasmic reticulum, free ribosomes and relatively few dense granules. in the summer these cells appear to be larger and many are packed with dense granules. fall cells exhibit morphological characteristics suggestive of intense synthetic activity, having rough-surfaced endopl ...1977920971
persistent free-running circannual reproductive cycles during prolonged exposure to a constant 12l:12d photoperiod in laboratory woodchucks (marmota monax).serum levels of gonadal steroid were assayed at approximately 3-month intervals in groups of 5 to 8 male or female woodchucks which were exposed to a natural photoperiod for 1 year as yearlings or 3 years as adults (study 1), or a constant photoperiod of 12l:12d from birth for 4.5 years (study 2). after 4.5 years of 12l:12d, food intake was measured in november and compared with that in natural photoperiod animals (study 3). other groups of 11 males and 3 females were housed in 12l:12d for 2.5 y ...19921434500
seasonal ultrastructural variations in pinealocytes of the woodchuck, marmota monax.the ultrastructure of the pinealocyte in the woodchuck, marmota monax, was studied during the four seasons of the year. fall cells have a fairly uniform cytoplasmic density, organelles consistent with synthetic and/or secretory activity and rather extensive pericapillary and intercellular spaces. many winter pinealocytes are nearly devoid of ribosomes and granular endoplasmic reticulum but contain lipid droplets associated with mitochondria. pericapillary and intercellular spaces are minimal. sp ...1978722791
the parathyroid gland of the woodchuck (marmota monax): a study of seasonal variations in the chief cells.the ultrastructure of the parathyroid chief cell in the woodchuck, marmota monax, was studied during the four seasons of the year. spring chief cells have stacks of granular endoplasmic reticulum, prominent multiple golgi zones and many clumped mitochondria. summer cells resemble those seen in the spring but the mitochondria are associated with stacks of granular endoplasmic reticulum. multiple areas of stacked granular endoplasmic reticulum characterize the fall chief cells. their golgi zones a ...1978675665
rabies and cerebrospinal nematodosis in woodchucks (marmota monax) from new york.abnormal behavior, suggestive of rabies, is not an unusual finding in woodchucks (marmota monax). necropsy records, rabies antibody tests, and necropsy examinations performed by the authors indicate that migration of ascarid larvae usually is responsible for the abnormal behavior, and that rabies is an infrequent finding. baermannization of brain tissue is suggested for a differential diagnosis.1978668397
respiratory mechanics of the coatimundi and woodchuck.the coatimundi breathes with a large tidal volume and relatively short te/ttot while the woodchuck has a relatively long te/ttot compared to other mammals. hence, the respiratory mechanics of the coatimundi and woodchuck were studied to determine whether mechanics play any role in the differences in breathing pattern observed in these two mammals of similar body size. although static respiratory system compliance was less and lower airway resistance was greater in the woodchuck compared to the c ...19921439297
the woodchuck, marmota monax, as a laboratory animal.the woodchuck or groundhog (marmota monax) has been used as a biomedical model for studies of obesity and energy balance, endocrine and metabolic function, central nervous system control mechanisms and cardiovascular, cerebrovascular and neoplastic disease. methods of care of a woodchuck colony, techniques for handling, restraint, anesthesia, blood sampling and breeding were developed.1979529775
species differences in cell culture of mammalian articular chondrocytes.articular chondrocytes from eight mammalian species (rabbit, opossum, woodchuck, cat, dog, sheep, rhesus and cebus monkeys) were grown in monolayer culture using a single regimen. the animals were immature or young adults. ham's f12 medium supplemented with 10% fetal bovine serum was employed for the primary cultures and dulbecco-vogt medium, for the secondary. marked species differences were found with respect to cell morphology, growth in primary and secondary cultures, incorporation of radios ...1977407988
a virus similar to human hepatitis b virus associated with hepatitis and hepatoma in woodchucks.particles with properties similar to those associated with human hepatitis b were found in serum from woodchucks with chronic hepatitis and hepatocellular carcinoma. it is suggested that woodchuck hepatitis virus is a second member of a novel class of viruses represented by the human hepatitis b virus.1978212758
hepatomas in a group of captive woodchucks. 1975170238
brain trh, monoamines, tyrosine hydoxylase, and tryptophan hydroxylase in the woodchuck, maromota monax, during the hibernation season. 197940745
a topological model for hepatitis b surface antigen.a model of hepatitis b surface antigen has been derived, based on extensive sequence analysis and biochemical data. the surface antigen sequences of the human, woodchuck, ground squirrel and duck hepadnaviruses were examined using hydrophobicity, hydrophobic moments, flexibility and secondary structure prediction. the helix phase diagram, which is a modified version of eisenberg's hydrophobic moment plots and which specifically addresses the problem of transmembrane helices, was used to examine ...19921500275
the precore gene of the woodchuck hepatitis virus genome is not essential for viral replication in the natural host.a number of naturally occurring hepatitis b virus mutants that cannot synthesize the virus precore protein have been identified. such mutants have been associated with more severe forms of hepatitis, including fulminant hepatitis. the most common mutation observed is a substitution of g to a in the distal precore gene that converts a codon specifying trp (tgg) to a termination codon (tag). using oligonucleotide-directed mutagenesis, we have produced the same point mutation in the precore gene of ...19921501300
a preliminary report of a controlled study of thymosin alpha-1 in the woodchuck model of hepadnavirus infection. 19921514437
further observations on estrus and ovulation in woodchucks (marmota monax) in captivity.the woodchuck is a seasonally breeding sciurid rodent. female woodchucks are monoestrous and, when isolated from males, remain in a prolonged period of estrus characterized by a clear predominance of cornified cells in the vaginal smear. this study was designed to characterize relationships between the degree of vaginal cornification and sexual receptivity, and to study ovulation and related phenomena of this species in captivity. fourteen individually caged adult females, maintained under stand ...19921547305
assembly of hepatitis delta virus particles.hepatitis delta virus (hdv) is a subviral satellite of hepatitis b virus (hbv). since the rna genome of hdv can replicate in cultured cells in the absence of hbv, it has been suggested that the only helper function of hbv is to supply hbv coat proteins in the assembly process of hdv particles. to examine the factors involved in such virion assembly, we transiently cotransfected cells with various hepadnavirus constructs and cdnas of hdv and analyzed the particles released into the medium. we rep ...19921548764
development and growth pattern of small hepatocellular carcinomas in woodchucks--analysis of an animal model of human hepatocellular carcinoma by ultrasonography.woodchucks are very useful animal models of human hepatocellular carcinoma. it is important to detect carcinomas in their early stage to study the pathogenesis of hepatocellular carcinoma. by ultrasonography (echogram) we found tumors less than 10 mm in diameter. echographically all of the tumors except one were hypo-echoic in their early stages. one tumor showed a hyper-echoic pattern which grew very rapidly. pathologically they were all well differentiated hepatocellular carcinoma and there we ...19911748173
frequent amplification of c-myc in ground squirrel liver tumors associated with past or ongoing infection with a hepadnavirus.persistent infection with hepatitis b virus (hbv) is a major cause of hepatocellular carcinoma (hcc) in humans. hcc has also been observed in animals chronically infected with two other hepadnaviruses: ground squirrel hepatitis virus (gshv) and woodchuck hepatitis virus (whv). a distinctive feature of whv is the early onset of woodchuck tumors, which may be correlated with a direct role of the virus as an insertional mutagen of myc genes: c-myc, n-myc, and predominantly the woodchuck n-myc2 retr ...19921570307
the structure of hepadnaviral core antigens. identification of free thiols and determination of the disulfide bonding pattern.a set of wild-type and mutant human, woodchuck, and duck hepatitis viral core proteins have been prepared and used to study the free thiol groups and the disulfide bonding pattern present within the core particle. human (hbcag) and woodchuck (whcag) core proteins contain 4 cysteine residues, whereas duck (dhcag) core protein contains a single cysteine residue. each of the cysteines of hbcag has been eliminated, either singly or in combinations, by a two-step mutagenesis procedure. all of the pro ...19921577770
microscopic anatomy of the skin of the woodchuck (marmota monax): comparison of woodchuck hepatitis virus-infected and non-infected animals.thirty-three woodchucks were used in this study. seventeen animals were healthy adults, not infected with woodchuck hepatitis virus (whv); 10 were healthy adults infected with whv; 4 were noninfected neonates; 2 were infected neonates. within the 4 groups of woodchucks, no histologic differences were detected on the basis of sex or age. neither were histologic findings different between infected and noninfected woodchucks of similar ages. the average thickness of skin (as measured from the skin ...19921424633
skin disorders of the laboratory woodchuck (marmota monax): a retrospective study of 113 cases (1980-1990).an 11-year retrospective study was conducted on the dermatoses occurring in 113 woodchucks from a colony at the college of veterinary medicine at cornell university. bacterial dermatitis was the most common dermatologic disorder, accounting for 70.2% of the cases. the highest incidence of bacterial dermatitis occurred in september/october prior to hibernation and in february/march during the breeding season. other dermatoses observed during the study period included taenia crassiceps infection, ...19921424634
effect of cyclosporin-a in woodchucks with chronic hepatitis delta virus infection.four woodchucks chronically infected with hepatitis delta virus (hdv) were treated with cyclosporin-a (cya) for 11 weeks. all animals had detectable hdag in the liver and two of them were also positive for hdag and hdv-rna in serum. reappearance of hdv in serum was noted in one of the two non-viraemic animals and increased viraemia in the two viraemic. hdv-rna levels became elevated within a week of starting treatment and an inverse relationship between hdv-rna and whv-dna became apparent during ...19921578224
effects of 2'-fluorinated arabinosyl-pyrimidine nucleosides on duck hepatitis b virus dna level in serum and liver of chronically infected ducks.the 2'-fluorinated arabinosyl-pyrimidine nucleosides, 1-(2'-deoxy-2'-fluoro-beta-d-arabinofuranosyl)-5-iodocytosine (fiac) and 1-(2'-deoxy-2'-fluoro-beta-d-arabinofuranosyl)-5-methyluracil (fmau), are new antiviral compounds with in vitro inhibitory activity against the dna polymerase of hepadnaviruses. those compounds also induced permanent inhibition of viral replication in woodchucks chronically infected by woodchuck hepatitis virus. the effects of these antiviral compounds were assessed in d ...19921629711
immunopathology of glomerulonephritis associated with chronic woodchuck hepatitis virus infection in woodchucks (marmota monax).retrospective analysis of necropsy findings of 705 woodchucks was performed to determine the prevalence and morphology of immune-mediated glomerulonephritis, its relationship to woodchuck hepatitis virus (whv) infection, and the presence of major whv antigens. twenty-six woodchucks had glomerular lesions. renal tissue of the 26 animals was evaluated histologically and immunohistochemically for immune-mediated glomerulonephritis. of these 26 animals, immune-mediated glomerulonephritis was diagnos ...19921632459
cellular and molecular mechanisms of hepatocarcinogenesis.for colorectal carcinomas, the rate of tumor development is proportional to the fourth to sixth power of elapsed time, suggesting that four to six independent events are necessary. although similar calculations have not been made for hbv-associated hccs, it is likely that this is also the case for hccs, since individuals with persistent hbv infection do not usually develop hcc until they are 45 or greater years old. as evidence for specific genetic and epigenetic changes in hccs accumulate, the ...19921439879
detection of mammalian and avian hepadnaviruses by the polymerase chain reaction.the hepadnavirus family contains a number of related viruses able to infect a variety of animal species. in the present study, we have used the polymerase chain reaction and oligonucleotide primers to a conserved region of the viral replicase gene of hepadnaviruses to identify viral sequences in de novo tissues in three well-characterized hepadnavirus systems: the woodchuck, ground squirrel and pekin duck. we did not detect related hepadnavirus sequences in liver specimens from tree squirrels pu ...19921455624
benzo(a)pyrene-blood protein adducts in wild woodchucks used as biological sentinels of environmental polycyclic aromatic hydrocarbons contamination.levels of benzo(a)pyrene-diolepoxide (bapde)-albumin and bapde-hemoglobin adducts in wild woodchucks (marmota monax) have been measured to evaluate the potential usefulness of these parameters in the assessment of environmental contamination by polycyclic aromatic hydrocarbons (pahs). blood was obtained from nine woodchucks living near an aluminum electrolysis plant, contaminated area (saguenay region, québec, canada), and from eight living in a control area (saint-roch-des-aulnaies, québec, can ...19921456777
alpha-fetoprotein in the woodchuck model of hepadnavirus infection and disease: normal physiological patterns and responses to woodchuck hepatitis virus infection and hepatocellular carcinoma.persistent infection of the eastern woodchuck (marmota monax) with the woodchuck hepatitis virus (whv) produces disease sequelae similar to those observed in humans with persistent hepatitis b virus infection, including hepatocellular carcinoma (hcc). to further characterize serological markers of hcc in the woodchuck, serum alpha-fetoprotein (afp) was measured under normal physiological conditions and following infection with whv. serum afp was elevated in association with whv-induced hepatitis ...19901701355
immunosuppression with cyclosporine during the incubation period of experimental woodchuck hepatitis virus infection increases the frequency of chronic infection in adult woodchucks.the immunosuppressive agent cyclosporine was given to adult woodchucks during acute experimental infection with woodchuck hepatitis virus (whv). all 17 woodchucks given whv alone or with a vehicle resolved the infection (i.e., zero chronicity), but when cyclosporine was given throughout the incubation and acute phases of infection (0-12 or 14 weeks; n = 12), the rate of chronic infection increased to 92%. when cyclosporine was given only during the incubation period (0-4 weeks; n = 10) or only d ...19921500746
adenine arabinoside monophosphate and acyclovir monophosphate coupled to lactosaminated albumin reduce woodchuck hepatitis virus viremia at doses lower than do the unconjugated drugs.the woodchuck was selected to study the efficacy of liver-targeted antiviral drugs on hepadnavirus replication. nineteen woodchucks chronically infected with woodchuck hepatitis virus were treated with adenine arabinoside monophosphate or acyclovir monophosphate, either free or conjugated with the liver-targeting molecule lactosaminated human serum albumin. circulating woodchuck hepatitis virus dna levels remained unchanged in untreated animals and in those receiving the carrier lactosaminated h ...19911712338
spotted fever group rickettsiae or borrelia burgdorferi in ixodes cookei (ixodidae) in connecticut.immatures and females of ixodes cookei, a hard-bodied tick, were collected from woodchucks and other mammals in the northeastern united states and examined for spotted fever group rickettsiae and borrelia burgdorferi. of the 93 nymphs analyzed by a hemolymph test, 4 (4.3%) harbored rickettsiae. six (15%) of 40 females were also infected. all infected ticks were collected from woodchucks in connecticut. indirect fluorescent antibody staining of midgut tissues from 128 nymphs revealed b. burgdorfe ...19911885748
an in situ hybridization, molecular biological and immunohistochemical study of hepatitis delta virus in woodchucks.the presence of hepatitis delta virus genomic rna and hepatitis delta antigen was investigated in woodchuck liver and extrahepatic tissues by in situ hybridization using synthetic radiolabeled probes, northern-blot analysis and immunohistochemical staining for hepatitis delta antigen. hepatitis d virus rna and hepatitis delta antigen were detected in the nuclei of infected hepatocytes but in none of the other tissues examined. northern-blot analysis of total cell rna confirmed these findings and ...19911714875
demonstration of woodchuck hepatitis virus infection of peripheral blood mononuclear cells by flow cytometry and polymerase chain reaction.peripheral blood mononuclear cells (pbmcs) from 10 woodchuck hepatitis virus (whv)-infected woodchucks were examined for the presence of whv surface (whs) and core (whc) antigens (whsag and whcag) by cytofluorometry using fluorescein isothiocyanate-conjugated anti-whs and anti-hbc-purified immunoglobulins from woodchuck and human sera. the presence of viral dna and rna was detected in the serum and pbmcs from the same blood samples by polymerase chain reaction (pcr) with two primer sets located ...19921730932
animal models of hepatocellular carcinoma: hepadnavirus-induced liver cancer in woodchucks.woodchuck hepatitis virus (whv), a member of the hepadnaviridae, is closely related to hepatitis-b virus (hbv) in its virus structure, genetic organization, and mechanism of replication. as with hbv in man, persistent whv infection is common in natural woodchuck populations and is associated with chronic hepatitis and hepatocellular carcinoma (hcc). experimental studies have established that whv causes hcc in woodchucks. chronic whv carriage as an outcome of experimental infection is a function ...19911751825
reinitiation of spermatogenesis by exogenous gonadotropins in a seasonal breeder, the woodchuck (marmota monax), during gonadal inactivity.the present study was undertaken (1) to document structural and functional changes in the testes of seasonally breeding woodchuck during active and inactive states of spermatogenesis and (2) to evaluate the ability of exogenous gonadotropins to reinitiate spermatogenesis outside the breeding season. during seasonal gonadal inactivity, there were significant (p less than 0.05) reductions in volumes of several testicular features (testis, seminiferous tubules, tubular lumen, interstitial tissue, i ...19911759684
[hepatitis b virus and hepatocellular carcinoma].hepatocellular carcinoma in woodchuck were characterized for woodchuck hepatitis virus integration nea c-myc oncogene. in one tumor, viral integration resulted in overexpression of a c-myc viral cotranscript. in a second tumor, viral insertion, 600 bp upstream of c-myc exon 1, was associated with increased levels of normal c-myc mrna. these results demonstrate that integration of woodchuck hepatitis virus near a proto-oncogene can contribute to the genesis of liver tumors. from a comparison of a ...19911772242
cyclosporin a modulates the course of woodchuck hepatitis virus infection and induces chronicity.immunosuppression is known to influence the state of chronic hepatitis b virus infection, and is thought to increase the risk of developing chronic infection in newly exposed individuals. cyclosporin a (csa), an immunosuppressive agent that inhibits th cell function, was administered to woodchucks chronically infected with woodchuck hepatitis virus (whv), and resulted in a decreased severity of chronic hepatitis and an increased viremia during the treatment. adult woodchucks inoculated with whv ...19911826706
interference of antiviral substances with replication of hepatitis delta virus rna in primary woodchuck hepatocytes. 19911826953
novel repeats in the genome of the woodchuck marmota monax. 19911840660
spliced rna of woodchuck hepatitis virus.polymerase chain reaction was used to investigate rna splicing in liver of woodchucks infected with woodchuck hepatitis virus (whv). two spliced species were detected, and the splice junctions were sequenced. the larger spliced rna has an intron of 1300 nucleotides, and the smaller spliced sequence shows an additional downstream intron of 1104 nucleotides. we did not detect singly spliced sequences from which the smaller intron alone was removed. control experiments showed that spliced sequences ...19921604814
prevention of radioactive indicator and viral particle transmission with an ointment barrier.to determine the efficacy of a lanolin-based gel in preventing radioactive particle and viral penetration.19911849933
nitrite and nitrosamine synthesis by hepatocytes isolated from normal woodchucks (marmota monax) and woodchucks chronically infected with woodchuck hepatitis virus.hepatocytes isolated from woodchucks (marmota monax) were shown to produce nitrite in vitro from l-arginine after stimulation with lipopolysaccharide (lps). hepatocytes isolated from woodchucks that were chronic carriers of woodchuck hepatitis virus formed twice as much nitrite as hepatocytes from noninfected animals. nitrite synthesis by hepatocytes was directly related to l-arginine and lps concentrations in the tissue culture medium and reached a plateau at 0.5 mm l-arginine and 1.0 microgram ...19921638528
the estrous cycle of captive woodchucks (marmota monax).changes in vaginal cytology were assessed and correlated with temporal changes in circulating concentrations of progesterone (p) and estradiol-17 beta (e2) during the breeding season (february to march) in a seasonally breeding rodent, the woodchuck (marmota monax). ten individually caged adult females, maintained under laboratory conditions for 3-11 mo, were studied. vaginal smears were taken each morning for 2 consecutive months beginning 1 february 1990. seven of 10 females exhibited readily ...19912043743
full-length and truncated versions of the hepatitis b virus (hbv) x protein (px) transactivate the cmyc protooncogene at the transcriptional level.the products of the human hepatitis b virus (hbv) and woodchuck hepatitis b virus x genes (pxs) transactivate homologous and heterologous genes including the hbv-x and core promoters, the human immunodeficiency viruses 1 (hiv-1) and 2 (hiv-2) long terminal repeats and the beta interferon regulatory sequences. we report here that px is also able to influence the expression of both extrachromosomal transfected c-myc regulatory sequences and endogenous c-myc gene. px acts by increasing transcriptio ...19911645550
[iron oxide-enhanced mr imaging of hepatocellular carcinoma of woodchuck].to determine the utility of iron oxide-enhanced mr imaging for primary hepatocellular carcinoma (hcc), mr imagings of an adult woodchuck with two nodules of hcc was obtained before and after an injection of iron oxide. on postcontrast images, signal intensity decreased in one nodule and did not change in the other. pathologically, the former was well-differentiated hcc with trabecular pattern and the latter was with pseudograndular and scirrhous pattern. iron oxide particles were noted within th ...19911648709
lack of pre-c region mutation in woodchuck hepatitis virus from seroconverted woodchucks.woodchuck hepatitis virus, which shares a large degree of homology with human hbv, was examined for indications of mutational variants. no alteration in the pre-c region was found, but as in hbv, viral dna could still be detected by pcr after seroconversion to anti-whe.19921450731
[hepatitis b virus and hepatocellular carcinoma].hepatocellular carcinomas in woodchuck were characterized for woodchuck hepatitis virus integration near c-myc oncogene. in one tumor, viral integration resulted in overexpression of a c-myc viral cotranscript. in a second tumor, viral insertion, 600 bp upstream of c-myc exon 1, was associated with increased levels of normal c-myc mrna. these results demonstrate that integration of woodchuck hepatitis virus near a proto-oncogene can contribute to the genesis of liver tumors. from a comparison of ...19911650625
phenotypic patterns of preneoplastic and neoplastic hepatic lesions in woodchucks infected with woodchuck hepatitis virus.chronic infection of woodchucks with woodchuck hepatitis virus (whv) was associated with the development of hepatitis, foci of altered hepatocytes and hepatocellular adenomas and carcinomas. the cytomorphological and cytochemical analysis permitted the identification of three different types of focal lesions; namely, glycogen-storage foci, mixed-cell foci and intermediate-cell foci, each showing a characteristic pattern. the cells of the glycogen-storage foci had clear to acidophilic cytoplasm, ...19902152341
analysis of insulin-like growth factor ii (igf-ii) expression in neoplastic nodules and hepatocellular carcinomas of woodchucks utilizing in situ hybridization and immunocytochemistry.hepatocarcinogenesis in woodchucks that are persistently infected with woodchuck hepatitis virus (whv) follows a progressive course characterized by foci of altered hepatocytes, benign neoplastic nodules and finally hepatocellular carcinoma (hcc). in situ hybridization studies have demonstrated that insulin-like growth factor ii (igf-ii) is expressed in most hccs in woodchucks but that the patterns of expression are variable from tumor to tumor. in some cases, expression of igf-ii is high throug ...19911657428
intracytoplasmic neuronal inclusions in woodchuck brain stem.homogenous eosinophilic intracytoplasmic inclusion bodies were found within the large reticular neurons of the brain stems of 57 captive woodchucks (marmota monax). light microscopy was consistent with a proteinaceous nature, while electron microscopy suggested a non-viral origin. the woodchucks with inclusions were older than the general population that was studied. it is hypothesized that the neuronal inclusions in the brain stem are indicative of nonspecific ageing changes.19902154630
immunogenic domains of hepatitis delta virus antigen: peptide mapping of epitopes recognized by human and woodchuck antibodies.hepatitis delta virus (hdv) is a defective rna virus which is dependent on hepatitis b virus for essential helper functions. only a single highly basic phosphoprotein, hdv antigen (hdag), is expressed by the hdv genome during infection in humans. antibody directed to hdag is important in the diagnosis of hdv infection, and it is likely but not yet proven that the immune response to hdag provides significant protection against subsequent exposures to hdv. in an effort to map the antigenic domains ...19901689390
alpha-fetoprotein in the woodchuck model of hepadnavirus infection and disease: immunochemical analysis of woodchuck alpha-fetoprotein and measurement in serum by quantitative monoclonal radioimmunoassay.woodchuck hepatitis virus infection of the eastern woodchuck represents a useful model for the study of hepatitis b virus infection and disease in humans, including hepatocellular carcinoma. in man, hepatocellular carcinoma is frequently detected and monitored using assays for serum alpha-fetoprotein. to study the relationship between alpha-fetoprotein and woodchuck hepatitis virus-induced hepatocellular carcinoma in the woodchuck model, we produced a monoclonal antibody to woodchuck alpha-fetop ...19901693355
two-day preservation of major organs with autoperfusion multiorgan preparation and hibernation induction trigger. a preliminary report.a new autoperfusion multiorgan preparation was studied in which the heart and lungs were removed with the liver, pancreas, duodenum, and both kidneys en bloc while being perfused by the heart and oxygenated by the lungs. a respirator with 50% oxygen was used for ventilation. fresh blood, glucose, electrolytes, mannitol, and antibiotics were given through the portal vein. fifteen mongrel dogs were used. in the study group (seven dogs), 10 ml of plasma containing hibernation induction trigger, obt ...19911865697
experimental hepatocellular carcinoma: mr receptor imaging.relaxation time measurements and magnetic resonance (mr) imaging were performed in three different animal models of hepatocellular carcinoma (hcc). after intravenous administration of asialoglycoprotein-directed arabinogalactan-stabilized ultrasmall superparamagnetic iron oxide (10 mumol fe/kg receptor agent), t2 of normal liver decreased from 41.6 msec +/- 1.0 to 19.4 msec +/- 1.7 (p less than .05) in rats. t2 of hcc implanted in normal liver or liver with chronic hepatitis was essentially unch ...19911871273
quantitation of aflatoxin b1-dna adducts in woodchuck hepatocytes and rat liver tissue by indirect immunofluorescence analysis.a quantitative indirect immunofluorescence technique was developed utilizing a monoclonal antibody (6a10) recognizing the imidazole ring-opened form of the major n-7 guanine adduct of aflatoxin b1 (afb1). this method was used to investigate adduct formation in woodchuck hepatocytes treated in culture and in liver tissue of rats treated i.p. with afb1. fluorescein isothiocyanate-labeled secondary antiserum was used for adduct localization in conjunction with 4',6-diamidino-2-phenylindole dihydroc ...19911900216
pathology of experimental schistosoma mansoni infection in the eastern woodchuck (marmota monax). 19911907047
the epidemiology of rodent and lagomorph rabies in maryland, 1981 to 1986.records from the maryland public health department were screened for confirmed rodent and lagomorph rabies between 1981 and 1986. questionnaires were designed for collection of information about events that led to the exposure of human and/or domestic animals to rabid rodent or lagomorphs. these species comprised 1.2% of all the reported rabies in the state. woodchucks (marmota monax) constituted 80.0% of all the reported rodent/lagomorph rabies cases in maryland. the majority showed aggressive ...19911920666
hepatitis delta virus cdna sequence from an acutely hbv-infected chimpanzee: sequence conservation in experimental animals.hepatitis delta virus (hdv) rna was isolated from the serum of a chimpanzee acutely infected with hepatitis b virus (hbv) and superinfected with hdv. interference of hdv with hbv resulted in decreased hbv dna levels in the serum. this interference did not change the size of the two hbv specific rnas present in the liver of the chimpanzee. the complete cdna sequence of the hdv rna (5th passage) was determined. comparison of this cdna sequence with our previously published sequence (4th passage), ...19911940877
trichinosis in a dog.trichinella spiralis infection was identified by direct fecal examination as the cause of gastrointestinal disease in a dog. the source of infection was believed to be a woodchuck. management included supportive care and benzimidazole treatment. vomiting, diarrhea, anorexia, and myalgia are the main signs of trichinosis, but routine fecal examination seldom reveals t spiralis in natural infections. mebendazole is the recommended anthelmintic and should be used to eliminate intestinal larvae and ...19902211292
endocrine correlates of hibernation-independent gonadal recrudescence and the limited late-winter breeding season in woodchucks, marmota monax.woodchucks (marmota monax) normally experience gonadal recrudescence towards the end of a 4-5 month hibernation, emerge in late winter, immediately breed in a short 3-week breeding season, and have regressed gonads before the next hibernation. our studies of wild and captive animals show that fertile females give birth to single litters after a 32-day gestation and their breeding season is terminated by a reactivation of the corpora lutea of pregnancy for 1-3 months immediately postpartum. in no ...19901974795
polymerase-related polypeptides associated with woodchuck hepatitis core antigen (whcag) particles.the woodchuck hepatitis virus (whv) polymerase (pol)-encoded polypeptide(s), obtained from purified virus nucleocapsid particles, have been characterized by western blotting. peptide antibodies to amino-terminal (residues 32-45, whv pol-6) and carboxy-terminal (residues 861-879, whv pol-1) sequences were used, in addition to monoclonal antibodies made from purified woodchuck hepatitis core antigen (whcag) particles. one of the monoclonal antibodies, wc pol-11, specifically bound whv pol-1. both ...19911984662
structure and expression of the woodchuck herpesvirus genome.this report describes the genome structure and location from which immediate-early transcription originates in the recently characterized woodchuck herpesvirus (herpesvirus marmota: hvm). cross-hybridization of restriction fragments indicates that the hvm genome contains a tandem array of 1.5-kb repeat units. additionally, terminal labeling and exonuclease experiments demonstrate that the repeated sequences lie at the termini of the genome. hybridization of probes representing immediate-early tr ...19911984663
woodchuck hepatitis virus is a more efficient oncogenic agent than ground squirrel hepatitis virus in a common host.chronic infection with hepatitis b viruses (hepadnaviruses) is a major cause of hepatocellular carcinoma (hcc), but the incubation time varies from 1 to 2 years to several decades in different host species infected with indigenous viruses. to discern the influence of viral and host factors on the kinetics of induction of hcc, we exploited the recent observation that ground squirrel hepatitis virus (gshv) is infectious in woodchucks (c. seeger, p. l. marion, d. ganem, and h. e. varmus, j. virol. ...19912002538
nucleotide sequence analysis of three different hepatitis delta viruses isolated from a woodchuck and humans.we have investigated the extent of hepatitis delta virus (hdv) genetic variability after serial passages in chimpanzees and woodchucks and between different human isolates. a complete hdv genome, isolated from a woodchuck liver, was cloned after five serial transmissions. the 1679 nucleotide long genome revealed only point mutations and a nucleotide divergence of 0.65% and 0.89% with previously published sequences of two epidemiologically related hdvs. we have obtained partial nucleotide sequenc ...19912005438
vaccinia recombinant virus expressing the rabies virus glycoprotein: safety and efficacy trials in canadian wildlife.twenty-six meadow voles (microtus pennsylvanicus), ten woodchucks (marmota monax), thirteen grey squirrels (sciurus carolinensis), thirteen ring-billed gulls (larus delawarensis), six red-tailed hawks (buteo jamaicensis) and eight great horned owls (bubo virginianus) received vaccinia virus recombinant expressing the rabies virus glycoprotein (v-rg) by direct instillation into the oral cavity. each of ten coyotes (canis latrans) received the virus in two vaccine-laden baits. several voles and mo ...19902249183
direct immunofluorescence testing of haired skin, nasal planum, and footpads of clinically normal woodchuck hepatitis virus-infected and non-infected woodchucks.the purpose of this study was to determine the frequency of immunoreactant deposition in the skin, footpad, and nasal planum of 10 clinically normal, non whv-infected woodchucks. the second part of the study investigated the frequency of immunoreactant deposition at the same sites in clinically normal, whv-infected woodchucks, and compared these results with those reported in humans. direct immunofluorescence testing of the haired skin, footpad, and nasal planum of all normal and 9 of the 10 whv ...19912029839
topoisomerase i-mediated integration of hepadnavirus dna in vitro.hepadnaviruses integrate in cellular dna via an illegitimate recombination mechanism, and clonally propagated integrations are present in most hepatocellular carcinomas which arise in hepadnavirus carriers. although integration is not specific for any viral or cellular sequence, highly preferred integration sites have been identified near the dr1 and dr2 sequences and in the cohesive overlap region of virion dna. we have mapped a set of preferred topoisomerase i (topo i) cleavage sites in the re ...19911850018
integration of woodchuck hepatitis virus (whv) dna at two chromosomal sites (vk and gag-like) in a hepatocellular carcinoma.integration of woodchuck hepatitis virus (whv) dna into the liver dna of a woodchuck infected by the virus was investigated. clonal viral integration was not detected three months before the appearance of four hepatocellular carcinomas (hcc). integration of the viral dna was detected in all four hccs, of which one was chosen to determine the structure of the viral integration completely in a single tumor. the integration occurred in two sites. one part contains the viral dna from the middle of t ...19912055466
autoantibody pattern in a woodchuck model of hepatitis b.spectrum, dynamics, and immunoglobulin class of the non-organ specific autoantibodies were investigated in 646 sequential sera from 18 woodchucks with experimental woodchuck hepatitis virus (whv) infection and in 8 naturally infected chronic carriers of the virus. among examined whv carriers, 8 animals developed hepatocellular carcinoma. the sera were tested by indirect immunofluorescence for autoantibodies against smooth muscle (sma), nuclei (ana), brush border of proximal renal tubuli (abba), ...19902078910
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