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immune tolerance in calomys callosus infected with machupo virus. 19695787102
isolation of machupo virus from wild rodent calomys callosus. 19665901620
chronic infection of rodents by machupo virus.machupo virus, the etiologic agent of human hemorrhagic fever in bolivia, induced chronic asymptomatic infection in laboratory hamsters and colonized individuals of the peridomestic, wild, south american rodent, calomys callosus. viruria was detected for more than 500 and 150 days, respectively, in the two species. chronic viremia was shown only for calomys. virus-neutralizing substances were present in parenterally infected adult animals, but not in animals born to, and in contact with, an infe ...19654956127
interferon-gamma levels during the course of trypanosoma cruzi infection of calomys callosus (rodentia-cricetidae) and swiss mice.serum levels of interferon-gamma (ifn-gamma) were evaluated in calomys callosus and swiss mice during the course of infection by four strains of trypanosoma cruzi. all strains stimulated the production of this interleukine; however, the timing of its onset and permanence varied among strains and between the two animal models. when chronically infected animals with no detectable serum ifn-gamma were challenged with the homologous strain, they produced quantities comparable with those obtained dur ...19957567909
macrophage activation and histopathological findings in calomys callosus and swiss mice infected with several strains of trypanosoma cruzi.peritoneal macrophage activation as measured by h2o2 release and histopathology was compared between swiss mice and calomys callosus, a wild rodent, reservoir of trypanosoma cruzi, during the course of infection with four strains of this parasite. in mice f and y strain infections result in high parasitemia and mortality while with silvatic strains costalimai and m226 parasitemia is sub-patent, with very low mortality. h2o2 release peaked at 33.6 and 59 nm/2 x 10(6) cells for strains y and f, re ...19921343663
number, size and distribution of ganglion neurons in urinary bladder of rodents.whole-mount preparations of urinary bladders stained with a modified giemsa technique were obtained from three rodent species (guinea-pig, calomys callosus and the c57/blj isogenic mouse) to identify and estimate the relative number and size of ganglionic neurons within the wall of the organ. the distribution of the ganglia was not uniform among the three species: ganglia were concentrated around the ureteral orifices in the guinea-pig, they were scattered throughout the organ in calomys callosu ...19948640241
modulation of antibody response to sheep red blood cells by cyclophosphamide in calomys callosus (rodentia).1. calomys callosus, a wild rodent reservoir of trypanosoma cruzi, notably resistant to laboratory infection with this parasite, is currently under study as a new experimental model for chagas' disease. 2. to investigate the humoral immune response of c. callosus, rodents were injected with sheep red blood cells (srbc) and the resulting antibody titers measured 0, 5, 9, 14, 20, 27 and 37 days later by the direct agglutination test. 3. modulation of the antibody response by cyclophosphamide (cy) ...19873331953
trypanosoma (herpetosoma) mariae n. sp., isolated from calomys callosus rengger, 1830 (rodentia-cricetinae). 1978727638
[kidney glomerular hemodynamics in the rodent calomys callosus].renal function was characterized in calomys callosus, a rodent which can participate in the transmission of several human diseases. the results showed that the pressures levels, hematocrit and plasmatic proteins were similar to rats submitted to the same experimental maneuvers. the corporal and renal weights, whole and single nephron glomerular filtration rates were similar to the mouse. this rodent presented a significant number of superficial glomeruli, allowing to evaluate glomerular hemodyna ...19892700392
the complement system of calomys callosus, rengger, 1830 (rodentia, cricetidae).the complement system (c) of calomys callosus, rengger, 1830 (rodentia, cricetidae), a wild reservoir for several infectious agents in latin america, was characterized. sera from normal adult animals lysed sheep erythrocytes (es) previously sensitized with rabbit serum anti-es (ar) in the presence of veronal-buffered saline containing 0.15 mm cacl2 and 0.5 mm mgcl2, ph 7.4, or unsensitized rabbit erythrocytes (er) in the presence of one-half isotonic strength veronal-buffered-saline containing 2 ...19921339512
modulation of parasitemia and antibody response to trypanosoma cruzi by cyclophosphamide in calomys callosus (rodentia, cricetidae).calomys callosus a wild rodent, previously described as harboring trypanosoma cruzi, has a low susceptibility to infection by this protozoan. experiments were designed to evaluate the contribution of the immune response to the resistance to t. cruzi infection exhibited by c. calossus. animals were submitted to injections of high (200 mg/kg body weight) and low (20 mg/kg body weight) doses of cyclophosphamide on days -1 or -1 and +5, and inoculated with 4 x 10(3) t. cruzi on day o. parasitemia, m ...19921307406
[various aspects of the behavior of wild strains of trypanosoma cruzi in mice and calomys callosus (rodentia)]. 1979398584
[note about the biology of cuterebra apicalis (guérin, 1829/38) (diptera-cuterebridae) (author's transl)].this note reports the parasitism by cuterebra apicalis guérin (1829/1838) on the rodents oryzomys eliurus and calomys callosus collected in the north of formosa county, goiás state. the infested animals were kept in the laboratory to allow observations on the development of the parasite.1978108773
[experimental infection of calomys callosus (rodentia-cricetidae) with leishmania donovani chagasi (laison, 1982)]. 19846393312
morphometry and acetylcholinesterase activity of the myenteric plexus of the wild mouse calomys callosus.the myenteric plexus of the digestive tract of the wild mouse calomys callosus was examined using a histochemical method that selectively stains nerve cells, and the acetylcholinesterase (ache) histochemical technique in whole-mount preparations. neuronal density was 1,500 +/- 116 neurons/cm2 (mean +/- sem) in the esophagus, 8,900 +/- 1,518 in the stomach, 9,000 +/- 711 in the jejunum and 13,100 +/- 2,089 in the colon. the difference in neuronal density between the esophagus and other regions wa ...19979283630
[experimental infection of calomys callosus (rodentia cricetidae) with trypanosoma cruzi]. 19826818675
calomys callosus: an alternative model to study fibrosis in schistosomiasis mansoni. the pathology of the acute phase.twenty calomys callosus, rengger, 1830 (rodentia-cricetidae) were studied in the early stage of the acute schistosomal mansoni infection (42nd day). the same number of swiss webster mice were used as a comparative standard. liver and intestinal sections, fixed in formalin-millonig and embedded in paraffin, were stained with hematoxilin and eosin, pas-alcian blue, ph = 1.0 and 2.5, lennert's giemsa, picrosirius plus polarization microscopy, periodic acid methanamine silver, gomori's silver reticu ...19958531679
nitric oxide involvement in experimental trypanosoma cruzi infection in calomys callosus and swiss mice.nitric oxide (no) production by peritoneal macrophages was evaluated in calomys callosus and swiss mice during the course of infection with two strains of trypanosoma cruzi. in c. callosus, no no production was detected throughout the period of observation in animals infected with either parasite strain, except for a very low amount measured on day 40 in animals infected with strain m226 and on the 28th day in animals infected with strain f after in vitro stimulation with interferon gamma (ifn-g ...19979342740
experimental infection of calomys callosus (rodentia, cricetidae) by toxoplasma gondii.calomys callosus, rengger 1830 (rodentia, cricetidae), a wild rodent found in central brazil, was studied to investigate its susceptibility to toxoplasma gondii experimental infection and its humoral immune response against this protozoa. the electrophoretic profile of the serum proteins of c. callosus showed that igg, which shows no affinity to protein a, has higher cross reactivity with rat igg than with igg from other rodents. the susceptibility assay was performed by inoculation groups of an ...19989698850
gamma-ifn and macrophage respiratory burst in calomys callosus challenged with trypanosoma cruzi bloodstream and metacyclic forms.parasitemia levels of calomys callosus inoculated with a high dose (hbt) of 4 x 10(3) trypanosoma cruzi strain m226 bloodstream trypomastigotes (bt) exceeded those with the same inoculum of metacyclic trypomastigotes (mt) while a similar parasitemia was obtained with a low dose (lbt) of 5 x 10(2) of bt. serum ifn-gamma levels during the acute phase of infection were higher in the lbt inoculated group when compared with the group inoculated with hbt, while the ifn-gamma levels in mt inoculated an ...19947829135
sera from chronic chagasic patients and rodents infected with trypanosoma cruzi inhibit trans-sialidase by recognizing its amino-terminal and catalytic domain.we investigated whether sera from chronic chagasic patients and animals infected with trypanosoma cruzi inhibit the removal of sialic acid from human erythrocytes and the transfer of sialic acid from sialyllactose to [14c]lactose in the reactions catalyzed by the parasite trans-sialidase. sera from swiss mice and calomys callosus animals infected with three different t. cruzi strains inhibit both reactions. inhibition increases during the infection, reaching maximal levels when the parasitemia d ...19948005683
effects of schistosomal mansoni infection on calomys callosus coelom-associated lymphomyeloid tissue (milky spots).calomys callosus rengger, 1830 (rodentia: cricetidae) is a mouse-like south american wild rodent, which is permissive to schistosoma mansoni infection. in this paper we studied the effect of schistosomal infection in c. callosus mesenteric and omental milky spots (ms), subsidiary foci of coelom-associated lymphomyeloid tissue (calt), during the acute, transitional (acute to chronic), and chronic phases of the infection. ms were morphologically analyzed by histological methods, using brightfield ...19989921319
acquired and congenital ocular toxoplasmosis experimentally induced in calomys callosus (rodentia, cricetidae).an experimental model for acquired and congenital ocular toxoplasmosis as well as a model to induce experimental autoimmune uveitis (eau) was investigated in calomys callosus. toxoplasma gondii, me-49 strain, was used to infect males and pregnant- and not pregnant-females while s-antigen, a major glycoprotein of the retinal photoreceptor cell, was used to induce eau. the ocular lesions elicited by t. gondii were characterized by the presence of cysts, free tachyzoites and inflammatory cells in t ...199910029920
morphological aspects of the myocarditis and myositis in calomys callosus experimentally infected with trypanosoma cruzi: fibrogenesis and spontaneous regression of fibrosis.calomys callosus a wild rodent, is a natural host of trypanosoma cruzi. twelve c. callosus were infected with 10(5) trypomastigotes of the f strain (a myotropic strain) of t. cruzi. parasitemia decreased on the 21st day becoming negative around the 40th day of infection. all animals survived but had positive parasitological tests, until the end of the experiment. the infected animals developed severe inflammation in the myocardium and skeletal muscle. this process was pronounced from the 26th to ...19947476222
wild rodents as experimental intermediate hosts of lagochilascaris minor leiper, 1909.a total of 25 specimens of cavia porcellus (guinea pig), 5 dasyprocta agouti (agouti), and 22 calomys callosus (vesper mice) were inoculated with infective eggs of lagochilascaris minor. the inoculum was prepared with embryonated eggs and orally administered to each individual animal through an esophagus probe. in parallel, 100 specimens of felis catus domesticus were individually fed with 55-70 nodules containing 3rd-stage larvae encysted in tissues of infected rodents. animals were examined an ...199910445999
influence of male gonadal hormones on the parasitemia and humoral response of male calomys callosus infected with the y strain of trypanosoma cruzi.effects of orchiectomy on male calomys callosus infected with the y strain of trypanosoma cruzi were studied. male c. callosus of the same age and weight were divided into three groups: intact, sham operated, and castrated. after 1 month they were inoculated (i.p.) with 4000 blood trypomastigotes. parasitemia was lower in orchiectomized animals than in the intact and sham groups. hormone replacement with decanoate testosterone raised the parasitemia of castrated animals to levels similar to thos ...199910494808
helminth fauna of the golden hamster mesocricetus auratus in brazil.helminth fauna of conventionally maintained hamsters from institutional animal houses that supply the research community with laboratory animals and from an openly kept control group, randomly purchased in a pet shop in the state of rio de janeiro, were evaluated and compared. necropsied animals from institutional suppliers were infected with the oxyurid nematodes syphacia criceti and s. mesocriceti and with the cestode rodentolepis nana; those from the pet shop were infected with s. mesocriceti ...200111300683
life cycle of ixodes (ixodes) loricatus (acari: ixodidae) under laboratory conditions.the life cycle of ixodes (ixodes) loricatus neumann, reared in the laboratory, is described. engorged females collected from opossums trapped in the states of minas gerais and são paulo, brazil, which were used to start the laboratory colonies, were designated as bmg and csp, respectively. larval and nymphal ticks from both colonies fed separately on rattus norvergicus berkenhout or calomys callosus rengger, whereas didelphis marsupialis l and didelphis albiventris lund were used as hosts for bm ...200011004783
fibrogenesis and collagen resorption in the heart and skeletal muscle of calomys callosus experimentally infected with trypanosoma cruzi: immunohistochemical identification of extracellular matrix components.intense inflammatory lesions and early development of interstitial fibrosis of the myocardium and skeletal muscle with spontaneous regression, have been described in calomys callosus infected with trypanosoma cruzi. the genetic types of collagen present in this model were investigated through immunohistochemistry using specific antibodies, combined with histopathology and picro-sirius staining of collagen. thirty-five calomys were infected with the colombian strain of t. cruzi and sacrificed at ...200212219139
transmission of yersinia pestis cultures with different plasmid content from xenopsylla cheopis to calomys callosus.most brazilian yersinia pestis isolates display a typical plasmid profile composed of the three classical plasmids: pyv, ppst and pfra. however, some cultures lack at least one of these plasmids, while a few of them harbour atypical dna bands of molecular weight ranging from 147 to 11.5 kb. to investigate whether y. pestis displaying atypical plasmid content could be propagated among rodents in nature through flea bites, we carried out studies with fleas ( xenopsylla cheopis) and rodents ( calom ...200312541056
new records and laboratory-rearing data for ixodes schulzei (acari: ixodidae) in brazil.ixodes schulzei aragão and fonseca was described from brazil in 1951 based on female ticks collected on wild rats from the states of rio de janeiro and santa catarina. since that time, there have been no additional reports of i. schulzei in the literature. we report two new records of i. schulzei: a female collected on the water rat nectomys squamipes (brants) from minas gerais state, and another female from this same host species from são paulo state. this last specimen was engorged and oviposi ...200312597665
influence of female gonadal hormones on the parasitemia of female calomys callosus infected with the "y" strain of trypanosoma cruzi.calomys callosus is a wild rodent found infected with trypanosoma cruzi in nature. groups of female c. callosus were subjected to ovariectomy or sham operation or served as intact controls. at 1 month after surgery, animals were inoculated intraperitoneally with 4000 blood trypomastigotes of the "y" strain of t. cruzi. parasitemia during the course of infection was significantly higher in ovariectomized animals as compared with sham-operated rodents and controls. on steroid hormone replacement t ...19989493207
life cycle of amblyomma cooperi (acari: ixodidae) using capybaras (hydrochaeris hydrochaeris) as hosts.the life cycle of amblyomma cooperi was evaluated under laboratory conditions testing different host species. larval infestations were performed on chickens (gallus gallus) and capybaras (hydrochaeris hydrochaeris). nymphal infestations were performed on g. gallus, h. hydrochaeris, guinea pigs (cavia porcellus) and wild mice (calomys callosus). infestations by adult ticks were performed only on capybaras. all free-living stages were observed in darkness at 27 degrees c and rh 85%. capybaras were ...200415139274
calomys callosus (rodentia : cricetidae) trophoblast cells as host cells to toxoplasma gondii in early pregnancy.the potential of the rh strain of toxoplasma gondii to invade trophoblast cells of the cricetid rodent calomys callosus in a congenital infection in the initial third of pregnancy was investigated in this study using morphological and immunocytochemical approaches. the animals were intraperitoneally inoculated on the 1st day of pregnancy and the infection was observed on day 7. various numbers of parasites could be observed inside the parasitophorous vacuoles in trophoblastic cells under light a ...199910431727
mast cells in the eyes of calomys callosus(rodentia: cricetidae) infected by toxoplasma gondii.the mast cell is a powerful effector cell for the innate immune system, acting through the secretion of several distinct mediators. few studies have demonstrated the relationship between mast cells and toxoplasmosis. in this study, mast cells were investigated in two experimental toxoplasma infections using calomys callosus (rodentia: cricetidae) as the host. animals were inoculated either intraperitoneally or via the conjunctiva with tachyzoites of toxoplasma gondii (rh strain) and sacrificed a ...200212107479
molecular genetic characterization of different trypanosoma cruzi strains and comparison of their development in mus musculus and calomys callosus.trypanosoma cruzi populations are characterized by diverse morphology, heterogeneous biological behavior, high genetic variability, and distinctly different clinical courses. the first objective of this work was to characterize different strains of t. cruzi with various molecular markers [simple-sequence-repeat pcr, randomly amplified polymorphic dna (rapd)-pcr, mini-exon genes]. all examined strains could be divided into two major lineages. only one strain showed a different banding pattern in ...200212107452
life-cycle and host specificity of amblyomma tigrinum (acari: ixodidae) under laboratory conditions.biological data of three generations of amblyomma tigrinum in the laboratory are reported and the suitability of different host species for immature ticks are compared. grouping the three generations, infestations by both the larval and nymphal stages were performed on chickens (gallus gallus), wistar rats (rattus norvegicus), rabbits (orytolagus cuniculus), wild mice (calomys callosus), dogs (canis familiaris) and opossums (didelphis albiventris). only dogs were used for infestations by adult t ...200212475081
infection of calomys callosus (rodentia cricetidae) with strains of different trypanosoma cruzi biodemes: pathogenicity, histotropism, and fibrosis induction.the influence of different trypanosoma cruzi biodemes on the evolution of the infection and on the histopathological lesions of the heart and skeletal muscles, during the experimental infection of calomys callosus, was investigated. three groups of c. callosus were infected, respectively, with parasite strains representative of three different biodemes: type i (y strain), type ii (21 sf strain), and type iii (colombian strain). for each group, normal c. callosus were also used as controls. marke ...200415322631
hantavirus pulmonary syndrome in northwestern argentina: circulation of laguna negra virus associated with calomys callosus.the purpose of this study was to characterize the hantaviruses circulating in northwestern argentina. human and rodent studies were conducted in yuto, where most cases of hantavirus pulmonary syndrome (hps) occur. partial virus genome sequences were obtained from the blood of 12 cases of hps, and from the lungs of 4 calomys callosus and 1 akodon simulator. phylogenetic analysis showed that three genotypes associated with hps circulate in yuto. laguna negra (ln) virus, associated with c. laucha i ...200415569801
hantavirus pulmonary syndrome in central bolivia: relationships between reservoir hosts, habitats, and viral genotypes.in august 2002, two cases of hantavirus pulmonary syndrome (hps) were confirmed in mineros and concepcion, within the santa cruz department of bolivia. extensive alteration of the native ecosystem, from dense forest to pasture or sugarcane, had occurred in both regions. an ecologic assessment of reservoir species associated with the human disease identified a single hantavirus antibody-positive oligoryzomys microtis from mineros and three hantavirus antibody-positive calomys callosus from concep ...200515728866
is nitric oxide involved in the tolerance of calomys callosus as a reservoir host towards trypanosoma cruzi infection?trypanosoma cruzi, the agent of chagas disease, is known to cause enhanced nitric oxide (no) production, which might be involved in host resistance. the inducible nitric-oxide-synthase (inos) is assumed to be responsible for the no increase after several infections. we studied the potential role of no in calomys callosus, a natural reservoir of this protozoan parasite. the concentration of no was determined in spleen and liver of animals infected with two different t. cruzi strains, bol and bol- ...200616368460
natural schistosoma mansoni infection in nectomys squamipes: histopathological and morphometric analysis in comparison to experimentally infected n. squamipes and c3h/he mice.histopathologic and morphometric (area, perimeter, major and minor diameters) analysis of hepatic granulomas isolated from twelve naturally infected nectomys squamipes were compared to four experimentally infected ones and six c3h/he mice. liver paraffin sections were stained for cells and extracellular matrix. both groups of n. squamipes presented peculiar granulomas consisting predominantly of large macrophages, full of schistosome pigment, characterizing an exudative-macrophage granuloma type ...200212426608
intestinal fibrovascular nodules caused by schistosoma mansoni infection in calomys callosus rengger, 1830 (rodentia: cricetidae): a model of concomitant fibrosis and angiogenesis.human schistosomiasis develops extensive and dense fibrosis in portal space, together with congested new blood vessels. this study demonstrates that calomys callosus infected with schistosoma mansoni also develops fibrovascular lesions, which are found in intestinal subserosa. animals were percutaneously infected with 70 cercariae and necropsied at 42, 45, 55, 80, 90 and 160 days after infection. intestinal sections were stained for brightfield, polarization microscopy, confocal laser scanning, ...200212426607
experimental life cycle of lagochilascaris major leiper, 1910 (nematoda: ascarididae) in cats (felis domesticus).the life cycle of lagochilascaris major was studied using eggs collected from a natural clinical case in a domestic cat. twenty-seven white mice (mus musculaus), 5 hamsters (mesocricetus auratus), and 1 vesper mouse (calomys callosus) were orally inoculated with 800-1,300 embryonated eggs. when examined from 73 to 246 days postinoculation (pi), encysted third-stage larvae were seen in skeletal muscles and less frequently in connective tissue, liver, and lungs. twenty-two of the 23 cats orally in ...200212537109
rodent control programmes in areas affected by bolivian haemorrhagic fever.bolivian haemorrhagic fever (bhf) caused by machupo virus is acquired by contact with the excretions and secretions of calomys callosus, an indigenous cricetine rodent which is preadapted to peridomestic habitats. it competes successfully with mus musculus, but not with rattus rattus. a successful disease control programme has functioned in beni department since 1964. it is based on trapping surveys and the detection of splenomegaly in calomys rodents as an index of chronic virus infection. mass ...1975182405
infection of wild and laboratory animals with machupo and latino viruses.natural infection with machupo and latino viruses occurs only in the cricetine rodent calomys callosus. machupo virus induces fatal infection in suckling mice and hamsters, and in adult guinea-pigs, marmosets, and rhesus monkeys. latino virus kills only suckling hamsters; it produces chronic but non-viraemic infection in calomys rodents.machupo virus, in contrast, induces a viraemic immunotolerant infection in suckling calomys, and a split response in animals more than 9 days of age. tolerant in ...1975182399
[on siphonaptera from rodents of formosa county, goiás state (author's transl)].polygenis bohlsi jordani (costa lima, 1937) (siphonaptera) is for the first time recorded as ectoparasite on wild rodents captured in the "cerrado" area of central brazil. seven out of nine rodents collected were found bearing p. b. jordani. the most common species found infested with the flea were: zygodontomys lasiurus, oryzomys eliurus, calomys callosus and nectomys squamipes.1979542652
natural nidality in bolivian hemorrhagic fever and the systematics of the reservoir species.zoonoses within wild reservoir host populations often occur focally obeying pavlovskii's rules of "natural nidality". what appears to be a clear example is bolivian hemorrhagic fever (bhf), a disease endemic to northeastern bolivia. the etiological agent is machupo virus (macv, arenaviridae). the vertebrate reservoir, identified 30 years ago, was calomys callosus a wild rodent common to open biomes in the lowlands of southeastern south america. the lack of concordance between the occurrence of m ...200212798015
toxoplasma gondii and mast cell interactions in vivo and in vitro: experimental infection approaches in calomys callosus (rodentia, cricetidae).in the present work, we studied some qualitative and quantitative characteristics of mast cells located in the peritoneal cavity, submandibular and dorsal lymph nodes and ileum of calomys callosus experimentally infected by toxoplasma gondii. in uninfected animals, the majority of mast cells had similar ultra-structural characteristics, including several cytoplasmic granules with homogeneous and electron dense contents. however, after 1 h of infection, a significant influx of mast cells into per ...200414998515
[studies on plasmodium atheruri].plasmodium atheruri, a parasite of the african porcupine atherurus africanus, is infective to splenectomised laboratory rats and mice, to hamsters and to 2 exotic rodents which are easily bred in captivity: calomys callosus and meriones unguiculatus. sporogony develops in anopheles stephensi fed on atherurus and on laboratory rodents; it is similar to that of the rodent plasmodia. exoerythrocytic schizogony usually lasts 4 to 6 days but schizonts have been found in the liver of a porcupine at da ...19836673640
could cyclophosphamide exert a protective role avoiding esophagic neuron loss in calomys callosus infected with trypanosoma cruzi?the protective role of cyclophosphamide was studied in this work. young male calomys callosus were infected with trypanosoma cruzi and allowed to age. cyclophosphamide therapy was administered to animals during acute and late chronic phases of infection. esophageal neurons were counted, displaying enhanced neuronal loss for the young and treated infected groups. for aged and cyclophosphamide treated animals, a protection was observed through a reduced loss of neurons as compared to the young and ...200818097753
disruption of myofibrillar proteins in cardiac muscle of calomys callosus chronically infected with trypanosoma cruzi and treated with immunosuppressive agent.calomys callosus (rodentia: cricetidae) chronically infected with cl strain of trypanosoma cruzi undergo recrudescence of the acute phase when treated with the immunosuppressor cyclophosphamide. the distribution of cytoskeletal proteins in cardiac tissue of immunosuppressed animals was mapped by immunofluorescence and electron microscopy to evaluate myofibrillar distribution during the intracellular life cycle of t. cruzi. cardiac muscle sections showed enhancement of myocarditis and parasite pr ...200516075261
morphological effects on the hard palatine mucosa of calomys callosus submitted to experimental chronic alcoholism.the morphological effects of ethanol ingestion on the hard palatine mucosa of adult male calomys callosus were observed. twenty rodents were divided into two experimental groups: the control group received solid diet, purina rat chow, and tap water ad libitum; the alcoholic group received the same solid diet and ethanol p.a. diluted 20% in water (v/v). after 270 days of treatment, all animals were sacrificed and the hard palatine mucosa were prepared for tem and sem methods. the epithelial cells ...200211995638
alterations triggered by steroid gonadal hormones in triglycerides and the cellular immune response of calomys callosus infected with the y strain of trypanosoma cruzi.calomys callosus is a wild rodent found naturally infected with different trypanosoma cruzi strains. in the work described here, groups of male and female c. callosus were subjected to orchiectomy, ovariectomy and sham operation. one month after surgery, animals were inoculated intraperitoneally (i.p.) with 4x10(4) blood trypomastigotes of the "y" strain of t. cruzi. parasitemia, triglycerides, nitric oxide (no) and concanavalin a (cona)-induced proliferation were evaluated. parasitemia during t ...200818242862
influence of trypanosoma cruzi chronic infection in the depletion of esophageal neurons in calomys callosus.the extent of neuronal loss was studied in this work, in aged female calomys callosus infected with the morc-1 strain of trypanosoma cruzi. fifteen months after infection, one group of animals was immunosuppressed with cyclophosphamide (cy). sections of the distal esophagus were collected and stained with cresyl violet. the neuron count was significantly different among groups, with enhanced neuronal loss in the infected group in comparison with the control aged noninfected group. partial protec ...200617203557
influence sexual dimorphism on the persistence of blood parasites in infected calomys callosus.gender has long been known to be a contributory factor in the incidence and progression of disorders associated with immune system disregulation. the aims of this experiment were to verify the influences of sexual dimorphism on the persistence of blood parasites out of the acute phase of infection. male and female calomys callosus were separated and infected with two strains of trypanosoma cruzi, and let age until 120 days. xenogiagnostic, culture of organs and blood, histopathology and lytic an ...200818328516
histological and serological evidence of experimental paracoccidioidomycosis in calomys callosus (rodentia: cricetidae).the responses of animal experimental models related to the infectivity, virulence and pathogenicity of paracoccidioides brasiliensis is constantly used to develop new perspectives of investigation. the rodent calomys callosus, rengger 1830 (rodentia: cricetidae) is an indigenous inhabitant of the savannah environment found in the central regions of brazil. the aim of the present work was to evaluate the histopathological and serological features of c. callosus after inoculation with the pb18 str ...200717244339
effect of toxoplasma gondii infection kinetics on trophoblast cell population in calomys callosus, a model of congenital toxoplasmosis.this work evaluated the kinetics of events that occur in the placenta of calomys callosus after toxoplasma gondii infection. animals on the first day of pregnancy (dop) and virgin nonpregnant females were perorally infected with 20 cysts of t. gondii strain me49. after 100 days of infection, the virgin animals were mated and received an additional 20 cysts on the first dop. the placentas and the embryos from both acutely and chronically infected animals were analyzed up to day 20 of pregnancy by ...200212438390
in vivo comparison of the biocompatibility of two root canal sealers implanted into the subcutaneous connective tissue of rats.to evaluate the subcutaneous biocompatibility of 2 root canal sealers.200717320427
azithromycin reduces ocular infection during congenital transmission of toxoplasmosis in the calomys callosus model.toxoplasma gondii is a widely distributed obligatory intracellular parasite that causes severe disease to the fetus when transmitted during pregnancy. drugs used to avoid congenital transmission have shown side effects, and their efficacy is controversial. the most widely used treatment for acute toxoplasmosis during pregnancy is pyrimethamine plus sulfadiazine, which has several side effects. in this work, we tested the efficacy of azithromycin in reducing congenital transmission of t. gondii i ...200920050006
life cycle and host specificity of amblyomma triste (acari: ixodidae) under laboratory conditions.we report biological data of two generations of amblyomma triste in laboratory and compared the suitability of different host species. infestations by larval and nymphal stages were performed on guinea pigs (cavia porcellus), chickens (gallus gallus), rats (rattus norvegicus), rabbits (oryctolagus cuniculus), wild mice (calomys callosus), dogs (canis familiaris) and capybaras (hydrochaeris hydrochaeris). infestations by adult ticks were performed on dogs, capybaras and rabbits. tick developmenta ...200314756395
experimental infection of crested caracara (caracara plancus) with toxoplasma gondii simulating natural conditions.toxoplasma gondii affects mainly warm-blooded animals, including birds. even though previous experimental data indicate that raptors are resistant to clinical infection, there is no information regarding the susceptibility of brazilian birds of prey to t. gondii. the present study aimed to observe how the crested caracara, a common raptor in brazil, interacts with t. gondii using an experimental model. seven crested caracaras, seronegative for t. gondii, were separated into infected (n=5) and co ...201020451327
does cyclophosphamide play a protective role against neuronal loss in chronic t. cruzi infection?in this study, we verified the possible role of cyclophosphamide (cy) in protecting or not against neuronal losses in young and aged male calomys callosus chronically infected with the morc-1 strain of trypanosoma cruzi through numerical quantification of neurons from the myenteric plexus of the colon and quantification of nitric-oxide concentration (no) during the acute and chronic phase of infection. for this purpose, groups of young c. callosus were infected with the morc-1 strain of t. cruzi ...200818427991
morphological and quantitative study of ganglionated plexus of calomys callosus trachea.calomys callosus is a wild, native forest rodent found in south america. in brazil, this species has been reported to harbour the parasitic protozoan trypanosoma cruzi. the ganglionated plexus of this species was studied using whole-mount preparations of trachea that were stained using histological and histochemical methods. the histological methods were used to determine the position of the ganglia with respect to the trachea muscle and to determine the presence of elastic and collagen fibers. ...200818824417
models for an arenavirus infection in a rodent population: consequences of horizontal, vertical and sexual transmission.arenaviruses are associated with rodent-transmitted diseases in humans. five arenaviruses are known to cause human illness: lassa virus, junin virus, machupo virus, guanarito virus and sabia virus. in this investigation, we model the spread of machupo virus in its rodent host calomys callosus. machupo virus infection in humans is known as bolivian hemorrhagic fever (bhf) which has a mortality rate of approximately 5-30% [31]. machupo virus is transmitted among rodents through horizontal (direct ...200819278272
participation of cytokines in the necrotic-inflammatory lesions in the heart and skeletal muscles of calomys callosus infected with trypanosoma cruzi.calomys callosus, a sylvatic reservoir of trypanosoma cruzi, when infected with the colombian strain (biodeme type iii, t. cruzi i ) develops necrotic-inflammatory lesions and intense early fibrogenesis in the heart and skeletal muscles, that spontaneously regress. participation of pro-inflammatory and pro-fibrogenic cytokines, such as tumor necrosis factor-alpha (tnf-alpha), gamma interferon (ifn-gamma) , and tumor growth factor-beta (tgf-beta), in the pathogenesis of the lesions is herein stud ...200516184235
paracoccidioides brasiliensis pancreatic destruction in calomys callosus experimentally infected.the wild rodent calomys callosus is notably resistant to trypanosoma cruzi infection. in order to better characterize this animal model for experimental infections, we inoculated c. callosus intraperitoneally with paracoccidioides brasiliensis, a thermally dimorphic fungus that causes a chronic disease with severe granuloma formation in the mouse and humans. the dissemination of p. brasiliensis cells through the lungs, liver, pancreas, and spleen was assessed by histological analysis.200919422699
observations on natural and laboratory infection of rodents with the etiologic agent of korean hemorrhagic fever.studies were conducted to define the natural host range of the korean hemorrhagic fever (khf) agent in south korea, and to identify colonized rodents susceptible to this infection. eight species of field rodents were captured in areas of korea endemic for khf and their tissues were examined by immunofluorescence for the presence of khf antigen. one hundred and fourteen of 817 apodemus agrarius coreae captured between 1974 and 1978 had one or more positive organs. no positive organ was found in 2 ...19816786119
susceptibility to vertical transmission of toxoplasma gondii is temporally dependent on the preconceptional infection in calomys callosus.toxoplasma gondii is an obligate intracellular parasite that causes a variety of clinical syndromes, but the infection is more severe in immunocompromised individuals and in cases of congenital toxoplasmosis. this study aimed to verify if the susceptibility to vertical transmission of toxoplasma gondii is temporally dependent on the preconceptional infection in calomys callosus. twelve c. callosus females were infected with 20 cysts of t. gondii me49 strain and divided into three groups of four ...200717182099
experimental chagas' disease in orchiectomized calomys callosus infected with the cm strain of trypanosoma cruzi.the incidence and progression of disorders associated with an unbalanced immune response has among many factors the gender as a contributory factor. the aims of this work were to evaluate the effects of orchiectomy and the immune response during the experimental trypanosoma cruzi infection. young adult, male calomys callous were i.p. inoculated with 1 x 10(5) blood trypomastigotes of the cm strain of t. cruzi and divided in groups: control, sham and castrated. castrated group displayed significa ...201019698712
azithromycin inhibits vertical transmission of toxoplasma gondii in calomys callosus (rodentia: cricetidae).toxoplasma gondii infection during pregnancy may cause severe consequences to the embryo. current toxoplasmosis treatment for pregnant women is based on the administration of spiramycin or a drug combination as sulphadiazine-pyrimethamine-folinic acid (spfa) in cases of confirmed fetal infection. however, these drugs are few tolerated and present many disadvantages due to their toxic effects to the host. the aim of this study was to evaluate the effectiveness of different treatments on the verti ...200919703714
trypanosoma cruzi: effects of social stress in calomys callosus a natural reservoir of infection.social environment can represent a major source of stress affecting cortisol and/or corticosterone levels, thereby altering the immune response. we have investigated the effects of social isolation on the development of trypanosoma cruzi infection in female calomys callosus, a natural reservoir of this protozoan parasite. animals were divided in groups of five animals each. the animals of one group were kept together in a single cage. in a second group, four females were kept together in a cage ...200818387609
life cycle of ixodes luciae (acari: ixodidae) in the laboratory.the life cycle of ixodes luciae was evaluated for five consecutive generations in the laboratory. wild mice calomys callosus and laboratory rats rattus norvegicus were used as hosts for larvae and nymphs. for adult ticks, opossums didelphis aurita were used as hosts. off-host developmental periods were observed in an incubator at 27 degrees c and 95% rh. the life cycle of i. luciae lasted 95-97 days, excluding prefeeding periods. c. callosus, one of the natural host species for i. luciae immatur ...200919756745
isolation and molecular detection of neospora caninum from naturally infected sheep from brazil.neospora caninum was isolated from a naturally infected sheep from brazil by bioassay in dogs. approximately 70g of brain from each of two 4-month-old sheep with indirect fluorescent antibodies (>or=1:50) to n. caninum was offered to a different ifat negative dog (sheep n. 302, ifat 1:400-dog 1 and sheep n. 342, ifat 1:50-dog 2). parasite dna was detected in both sheep brains using a pcr targeting the nc-5 gene of n. caninum. shedding of neospora-like oocysts was noticed only in dog 1, from 10 d ...200717451882
trypanosoma cruzi strains in the calomys callosus: parasitemia and reaction of intracellular forms with stage-specific antibodies in the acute and chronic phase of infection and after immunosuppression.an experimental model for chronic chagas disease was developed to investigate whether reactivation is influenced by the genetic origin of trypanosoma cruzi isolates. in addition, we examined whether the distribution of t. cruzi stage-specific epitopes, as defined by monoclonal antibodies (mab), raised against mammalian-stage parasite forms, exhibited comparable distribution patterns in calomys callosus myocardium during the acute phase and after reactivation of the infection. animals were infect ...201121331788
distribution of trypanosoma cruzi stage-specific epitopes in cardiac muscle of calomys callosus, balb/c mice, and cultured cells infected with different infective forms.to examine whether distinct parasite infective forms or the mammalian host could affect the distribution of trypanosoma cruzi stage-specific epitopes defined by monoclonal antibodies (mabs) raised against mammalian-stage parasite forms, immunofluorescence studies followed the intracellular life cycle of the parasite in the cardiac muscle of calomys callosus and balb/c mice in the acute phase of the disease and in llc-mk(2) cultured cells. animals and cells were infected either with tissue-cultur ...200717582377
[ectoparasites of small wild mammals from the adjacent areas of itapecuru river and environmental preservation area of inhamum, state of maranhão, brazil].during fauna studies, thirty-six wild mammals were collected in adjacent areas of itapecuru river and environmental preservation area of inhamum, state of maranhão, brazil. they were sampled for ectoparasites. the following specimens of the order rodentia and its respective ectoparasites were identified: akodon sp. (androlaelaps sp. and laelaps sp.), oecomys sp. (androlaelaps sp. and amblyomma cajennense), oligoryzomys sp. (androlaelaps sp. laelaps sp. and amblyomma sp.) e oryzomys megacephalus ...200820059819
comparative evaluation of amblyomma ovale ticks infected and noninfected by rickettsia sp. strain atlantic rainforest, the agent of an emerging rickettsiosis in brazil.in 2010, a novel spotted fever group rickettsiosis was reported in the atlantic rainforest coast of brazil. the etiological agent was identified as rickettsia sp. strain atlantic rainforest, and the tick amblyomma ovale was incriminated as the presumed vector. the present study evaluated under laboratory conditions four colonies of a. ovale: two started from engorged females that were naturally infected by rickettsia sp. strain atlantic rainforest (designated as infected groups); the two others ...201626895674
morphological and biological features of trypanosoma (herpetosoma) mariae mello, 1978 in experimentally infected calomys callosus.in this paper some observations on the biology of trypanosoma (herpatosoma) mariae, mello, 1978 are presented. the experiments were carried out in calomys callosus (rodentia), reservoir of this parasite. the prepatent period varied from 6.6-10.5 days and the patent infection varied from 38-141 days. amastigote forms in divisions were seen mainly among the cellular spaces of the spleen. only trypomastigote forms were seen in the blood stream. measurements of these forms showed that the total leng ...19827125491
[a new laboratory rodent, cricetida calomys callosus]. 19674967372
neonatal transmission of t. cruzi in calomys callosus (rodentia) 19816800072
Life-cycle and host preference of Amblyomma ovale (Acari: Ixodidae) under laboratory conditions.This study evaluated for the first time the life cycle of Amblyomma ovale in the laboratory. For this purpose, larvae and nymphs were exposed to Gallus gallus (chickens), Cavia porcellus (guinea pigs), Rattus norvegicus (wistar rats), Oryctolagus cuniculus (domestic rabbits), Calomys callosus (vesper mouse), and Didelphis albiventris (white-eared opossum). Nymphs were also exposed to Nectomys squamipes (South American water rat). Adult ticks were fed on dogs. The life-cycle of A. ovale in labora ...201122113779
scanning electron microscopy study of the interface epithelium-connective tissue surface of the lingual mucosa in calomys callosus.the characteristics of the interface epithelium-connective tissue of the lingual mucosa of calomys callosus was studied by employing scanning electron microscopy after removal of the epithelial cells. in the anterior part, the connective tissue papillae of filiform papillae are distributed at random in their original configuration, and the round-shaped fungiform papillae are scattered among the filiform papillae. in the middle part, the filiform papillae present several rod-shaped projections. i ...19979059739
cytological aspects of vascular invasion by the trophoblast of calomys callosus in hepatic tissues.ectoplacental cones isolated from embryos on the seventh day of pregnancy were transplanted beneath the hepatic capsule of recipient adult animals to document the morphological patterns of vascular invasion by the trophoblast in the absence of the maternal environment and the influence of its peculiar vasculature. females, and females and males of calomys callosus, a cricetid rodent, were used, respectively, as embryo donors and recipient animals. three to 5 days later, the grafted regions were ...19957473766
fur mites of the family listrophoridae (acariformes: sarcoptoidea) associated with south american sigmodontine rodents (cricetidae: sigmodontinae).six species of 3 genera belonging to the fur mite family listrophoridae were recorded on skins of south american rodents of the cricetid subfamily sigmodontinae housed in the bavarian state collection of zoology (munich, germany). among them, amlistrophorus geoxus sp. nov. from geoxus valdivianus from chile is described as a new for science, and males of prolistrophorus amazonicus amazonicus fain, 1971 are recorded for the first time. the full generic status for the subgenus amlistrophorus of th ...201223129199
evaluation of vertical transmission of toxoplasma gondii in calomys callosus model after reinfection with heterologous and virulent strain.toxoplasma gondii is an obligate intracellular protozoan parasite that causes a variety of clinical syndromes, but the infection is severe in immunocompromised individuals and during pregnancy due to the possibility of transplacental transmission of the parasite causing congenital toxoplasmosis. vertical transmission of the parasite usually occurs when females are primarily infected during pregnancy. calomys callosus is resistant to t. gondii me49 strain, which presents a moderate virulence and ...201021146211
normal hematologic values of various age groups of calomys callosus (rodentia cricetidae).hematologic values for calomys callosus, a wild rodent, were established. males and females from a colony raised in animal housing of the institute of tropical medicine of são paulo were examined individually. for the red blood cell series, the number of erythrocytes, hemoglobin concentration, hematocrit, and platelet and reticulocyte numbers were measured. all values except hemoglobin concentration were slightly higher in aged animals than in young animals. the white blood cell series had a pre ...19958569156
trophoblastic invasion of the uterine epithelium in calomys callosus (rodentia, cricetidae).implantation sites in the uterus of the cricetid rodent calomys callosus were examined by light and electron microscopy at several points during day 4 of pregnancy to determine the changes occurring in the trophoblast and epithelial cells during the early blastocyst-endometrial relationship, particularly the epithelial removal phase. by morning, the blastocysts had already lodged in the antimesometrial region of the uterine crypts and the embryo-maternal interaction was limited to sparse contact ...19947932767
[calomys callosus rengger, 1830 (rodentia-cricetidae): its characterization, distribution, biology, breeding and management of a laboratory strain]. 20066379371
structural evaluation of the effects of chronic ethanol ingestion on the testis of calomys callosus.chronic exposure to ethanol may results in pathophysiologic changes in cellular function. the present work was designed to investigate the morphology of testis submitted to experimental ethanol ingestion. experimental animals were divided into two groups. the control group (n=23) received a solid diet and tap water and the alcoholic group (n=23) received the same solid diet and ethanol p.a. diluted 20% in water (v/v). after 120 days of treatment, all animals were anesthetized, weighed and sacrif ...200919058826
study of the social hierarchy and territoriality of calomys callosus rengger, 1830 (rodentia: cricetidae).the genus calomys comprises a lot of species distributed throughout south america. the species c. callosus rengger, 1830 occur in brazil, been often used in laboratory experiments. this work involved a study of aggressive behavior and dominance, which are aspects related to hierarchy and territoriality, among c. callosus males kept in a laboratory. the establishment of a hierarchy was observed, with the dominant animals controlling the space, food and water, while the remaining animals were conf ...200718094825
morphological alterations on the prostate of calomys callosus submitted to chronic ethanol ingestion.the objective of the present study was to assess the possible toxic effects of chronic alcohol ingestion on the ultrastructure of the glandular epithelium of the prostate of the rodent calomys callosus, in order to contribute to the understanding of the consequences of alcohol abuse for the morphology of the male reproductive apparatus. sixteen adult animals aged three months were divided into two experimental groups. the control group received a solid diet and tap water, and the alcoholic group ...201317784639
evaluation of the ethanol intake on the calomys callosus seminal vesicle structure.the effects of chronic alcohol ingestion on the structure of the glandular epithelium of the seminal vesicle of the rodent calomys callosus were analyzed in 24 adult animals aged 3 months divided into three experimental groups. the control group received a solid diet and tap water, the alcoholic group received the same solid diet and ethanol p.a. diluted 20% in water (v/v) for 4 months. the abstinent group received the same liquid diet of the alcoholic one for the same period and after that the ...200817693093
ultrastructural changes on the hard palatine mucosa of calomys callosus after 120 days of experimental chronic alcoholism.the present study analyzed the toxic effects of chronic alcohol ingestion on the ultrastructure of the lining epithelium of the hard palatine mucosa of the rodent calomys callosus, in order to contribute to the understanding of the consequences of alcohol abuse for the morphology of the digestive system. twenty-six adult animals aged three months were divided into two experimental groups. the control group received a solid diet and tap water, and the alcoholic group received the same solid diet ...200516144085
fine structure of the 7 postnatal days calomys callosus palatine salivary glands.the aim of this study has been to determine the ultrastructural characteristics of the minor palatine salivary glands on the seventh day of development and to demonstrate wether their secretion is mucous, serous or seromucous by light, transmission and scanning electron microscopy. this study has shown that the palatine gland acinar cells are predominantly mucous with some serous units. these cells contain electron dense (serous) and low electron dense (mucous) granules in the apical portions. t ...200212201044
novel babesia and hepatozoon agents infecting non-volant small mammals in the brazilian pantanal, with the first record of the tick ornithodoros guaporensis in brazil.taking into account the diversity of small terrestrial mammals of the pantanal, the present study aimed to verify the occurrence of infection by ehrlichia spp., anaplasma spp., rickettsia spp., hepatozoon spp., babesia spp. and parasitism by ticks in non-volant small mammals collected in the brazilian pantanal. samples of blood, liver and spleen were collected from 64 captured animals, 22 marsupials and 42 rodents. pathogen detection was performed by the use of genus-specific polymerase chain re ...201626782931
the role of sigmodontine rodents as sylvatic hosts of trypanosoma cruzi in the argentinean chaco.the role of rodents in the sylvatic transmission of trypanosoma cruzi has seldom been investigated using parasitological and molecular methods. we assessed the occurrence of t. cruzi in wild small rodents from pampa del indio, in the argentinean chaco, and identified the taxonomic status of positive rodents by sequencing a fragment of cytochrome b gene (cytb) and performing blast searches and phylogenetic analyses. a total of 176 sigmodontinae rodents was captured in six surveys using 5425 trap- ...201424394448
receptor determinants of zoonotic transmission of new world hemorrhagic fever arenaviruses.transferrin receptor 1 (tfr1) is a cellular receptor for the new world hemorrhagic fever arenaviruses machupo (macv), junín (junv), and guanarito (gtov). each of these viruses is specifically adapted to a distinct rodent host species, but all cause human disease. here we compare the ability of these viruses to use various mammalian transferrin receptor 1 (tfr1) orthologs, including those of the south american rodents that serve as reservoirs for macv, junv, and gtov (calomys callosus, calomys mu ...200818268337
morphology of the seminal vesicle of calomys callosus submitted to experimental chronic alcoholism.the objective of the present study was to assess the possible toxic effects of chronic alcohol ingestion on the ultrastructure of the lining epithelium of the seminal vesicle of the rodent calomys callosus, in order to contribute to the understanding of the consequences of alcohol abuse for the morphology of the male reproductive apparatus. twenty six adult animals aged three months were divided into two experimental groups. the control group received a solid diet (purina chow) and tap water, an ...200111989779
nadph-diaphorase activity and nitric oxide synthase isoforms in the trophoblast of calomys callosus.the pattern of expression of a variety of placental nitric oxide synthase isoforms has contributed to elucidating the regulatory mechanisms of nitric oxide (no) synthesis during gestation. the maintenance of vascular tone, attenuation of vasoconstriction, prevention of platelet and leukocyte adhesion to the trophoblast surface, and possible participation in uterine blood flow seem to be the main functions of no generated at the fetal-maternal interface in humans and mice. extending this knowledg ...200111327206
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