the role of the tail in temperature regulation of the cotton rat, sigmodon hispidus. 19751200
an evaluation of the zygomatic arch for separating juvenile from adult cotton rats (sigmodon hispidus). 1975167088
noise stress and in vitro adrenocortical responsiveness to acth in wild cotton rats, sigmodon hispidus. 1978210010
radiocesium uptake by a population of cotton rats (sigmodon hispidus) inhabiting the banks of a radioactive liquid waste pond. 1979422372
photoperiodic influences on gonadal development and maintenance in the cotton rat, sigmodon hispidus. 1979486631
field studies of systemic insecticides. iv. evaluation of phoxim for prevention of natural seasonal increases of fleas on the hispid cotton rat. 1977609076
[infection of wild rats with angiostrongylus costaricensis by intraperitoneal subcutaneous route].three groups of cotton rats (sigmodon hispidus) were infected with angiostrongylus costaricensis; the first was inoculated by stomach tube; the second intraperitoneally and the third subcutaneously. in all the groups each rat received 50 l3. the highest rates of infection (51.5%) were obtained by the intraperitoneal route, followed by oral inoculation (47.1%). poor results were observed (10.5%) subcutaneously.1977615323
venezuelan encephalitis virus infection in neotropical bats. ii. experimental infections.eighty-nine neotropical bats of five species were inoculated subcutaneously with epizootic or enzootic strains of venezuelan encephalitis (ve) virus. viremia was detected in 92.5% of all bats, but no illness attributable to virus infection was observed. detectable viremias averaged slightly over 4 days in artibeus jamaicensis and a. lituratus, and 2.8 days in phyllostomus discolor, and maximal viremia titers in these three species averaged 6.9, 6.6, and 4.6 log10 smicld50 per ml of blood, respec ...1978646022
cholelithiasis in the cottonrat, sigmodon hispidus, from the high plains of texas.a high prevalence (71%) of gallstones was noted in free-ranging cottonrats, sigmodon hispidus, collected from one site in lubbock county, texas. the gallbladder of affected animals was distended and filled with white, soft, friable, cholesterol gallstones of variable sizes. focal hyperplasia of the epithelium and connective tissue layer of the gallbladder was evident in affected cottonrats. as the forage available to affected animals was different from that available to gallstone-free animals co ...1978650786
evaluation of the intrathoracic injection method for screening of filaricides.intrathoracic injection technique was utilized to examine its value in screening of antifilaria drugs in litomosoides carinii in the cotton rat, sigmodon hispidus, using existing filaricides such as diethylcarbamazine, mel w. metrifonate, suramin, arsenics and antimonials. diethylcarbamazine at a dose of 100 mg/kg for 5 days given intrathoracically caused marked decrease of more than 95% of the microfilaria count in the blood 1 week after the initial injection which is the same effect as was obs ...1978748620
qualitative cranial characters distinguishing sigmodon hispidus and sigmodon arizonae and the distribution of these two species in northern mexico. 1978750644
taste preferences in the cotton rat (sigmodon hispidus).this study focused on taste preferences in hispid cotton rats (sigmodon hispidus) as measured by 2-bottle, 48-hr. drinking tests. in a series of continuous tests, fluid intakes were recorded for 5 sugar solutions (fructose, glucose, sucrose, maltose and lactose), 3 salt solutions (kcl, mgso4 and nacl), and 2 acid solutions. in as attempt to supplement incomplete and divergent comparative data on rodent's taste preferences, this study investigated sugar and salt preferences at five concentrations ...1977917691
endogenous stages of eimeria sigmodontis (protozoa: eimeriidae) in the cotton rat, sigmodon hispidus. 1977924723
observations on the involvement of wildlife in an epornitic of chlamydiosis in domestic an investigation of potential wildlife reservoirs of chlamydia psittaci at the site of an acute, highly fatal epornitic of chlamydiosis in domestic turkeys in texas, various species of wild birds and rodents were captured and tested for chlamydial serum antibodies and chlamydiae in their tissues. thirteen (65%) of 20 blackbirds (agelaius sp), 4 (44%) of 9 killdeer (oxyechus vociferus), 3 (27%) of 11 sparrows (passer sp) and 1 of 4 mourning doves (zenaidura macroura) were seropositive, but chl ...1976988009
experimental infection of north american mammals with epidemic venezuelan encephalitis virus.eighty-three wild mammals of ten species were inoculated with a first mouse passage level venezuelan encephalitis (ve) virus isolated from south texas in 1971 during the ve outbreak. rodents were highly susceptible to ve infection and circulated ve virus at levels ranging from 10(7.7) to 10(11.5) suckling mouse intracranial lethal doses per ml for 2 to 4 days. these levels of virus could easily infect vector mosquitoes. mortality was high in all species of rodents except sigmodon hispidus, adult ...19761008132
vaccination of foxes against rabies using ingested baits.a method for immunizing foxes against rabies was evaluated. fifteen of 36 red foxes (vulpes fulva) fed baits impregnated with modified live virus rabies vaccine developed serum rabies neutralizing antibody. the vaccine-bait proved unstable when held at 4 c or 25 c for 96 hours prior to feeding. for safety testing the vaccine virus was administered to opossums (didelphis virginiana), cotton rats (sigmodon hispidus), hamsters (mesocricetus auratus), and chickens (gallus domesticus) in either liqui ...19751097743
early lymphoreticular viral tropism and antigen persistence. tamiami virus infection in the cotton rat.tamiami virus was inoculated into its natural reservoir host, the cotton rat (sigmodon hispidus), and the course of infection was followed by sequential organ titrations, frozen-section immunofluorescence, and light and electron microscopy. in animals infected at 2 days of age, there was an early lymphoreticular tropism with peak concentrations of virus and viral antigen in lymph nodes, splenic white pulp, thymus, and bone marrow at 16 days postinoculation. megakaryocyte infection was early and ...19761249916
angiostrongylus costaricensis natural infection in vaginulus plebeius in nicaragua.a study of 94 slugs, collected from urban and rural areas in and around léon, nicaragua, was carried out in order to confirm the role of vaginulus plebeius as an intermediate host of angiostronglylus costaricensis. third-stage larvae of a. costaricensis were obtained from these molluscs. some of these larvae were then orally inoculated into two laboratory-bred rats sigmodon hispidus and adult worms of a. costaricensis were recovered two months later. the infection rate of these slugs ranged from ...19921290381
cotton rats and other small mammals as hosts for immature dermacentor variabilis (acari: ixodidae) in central oklahoma.eight species of small mammals were evaluated as potential hosts for american dog ticks, dermacentor variabilis (say), in an upland, tallgrass prairie study site in central oklahoma. only hispid cotton rats, sigmodon hispidus, and deer mice, peromyscus maniculatus, were found to be important hosts for immature d. variabilis. although d. varibilis larvae and nymphs frequently infested both cotton rats and deer mice, cotton rats were the most important host species for both immature stages in the ...19921404263
rodents are not a source of endogenously-produced, fecally-transmitted caryospora bigenetica oocysts.fifteen swiss-webster mice (mus musculus) and eight cotton rats (sigmodon hispidus) were inoculated orally with caryospora bigenetica oocysts. feces from these animals were collected from 0 to 180 days postinoculation (dpi) and examined for endogenously-produced oocysts using nomarski microscopy. oocysts were recovered from mouse feces at 0, 1, 2, 3, 5, 7, 8, 10, and 14 dpi, and from cotton rat feces at 1, 2, and 9 dpi. the recovered oocysts were determined to be from the original inocula due to ...19921512870
measles virus replication in lungs of hispid cotton rats after intranasal inoculation.hispid cotton rats were inoculated intranasally with either measles virus (mv) edmonston, a multipassaged, tissue culture-adapted strain of mv, or with one of three clinical mv isolates that had limited passages (three to five times) in tissue culture cells. mv edmonston was recovered from the lungs of every (n = 37) hispid cotton rat inoculated with this virus for at least 7 days after virus inoculation. peak pulmonary titers occurred on day +4 (3.3-4.4 log10/g lung). scattered areas of inflamm ...19921528912
gut associated lymphoid tissue in the cotton rat (sigmodon hispidus) and its response to protein restriction.we examined age and nutritional related changes in the distribution and size of gut associated lymphoid tissues in the intestinal tract of cotton rats (sigmodon hispidus). peyer's patches in the small intestine are prominent, ranging from four to 13, and increase in size (surface area) with age. the average peyer's patch in the adult cotton rat measured 23.9 mm2. lymphoid tissue in the cecum was primarily limited to a large aggregate located in the vermiform appendix, which increased in size wit ...19921548786
influence of habitat modification on the community of gastrointestinal helminths of cotton rats.dynamics of communities of gastrointestinal helminths of cotton rats (sigmodon hispidus) were monitored in response to five experimental brush management treatments using herbicide applications with and without prescribed burning on the cross timbers experimental range in payne county, oklahoma (usa). a total of 113 adult cotton rats (68 male and 45 female) was collected from experimental pastures in winter and summer 1986 resulting in the recovery of five species of helminths: longistriata adun ...19911758023
acute effects of benzene and cyclophosphamide exposure on cellular and humoral immunity of cotton rats, sigmodon hispidus. 19911863803
an established cell line of larval echinococcus multilocularis.a cell line of larval echinococcus multilocularis has been established from an echinococcal cyst excised surgically from a patient with alveolar hydatid disease. a standardized procedure established for the preparation and continuation of primary cultures was applied to isolate the e. multilocularis cells from the tissue fragments. trypsin was used for the enzymatic release of the monodispersed cells from the tissue fragments and for dispersing monolayers. the culture medium was rpmi 1640 with 1 ...19911869357
evaluation of ultrastructural hepatic response to environmental toxicants in wild cotton rats (sigmodon hispidus). 19911912711
o-dealkylation of resorufin ethers as an indicator of hepatic cytochrome p-450 isoenzyme induction in the cotton rat (sigmodon hispidus): a method for monitoring environmental contamination. 19911932860
recovery of adult stages and microfilaraemia after low dose inoculation of third stage larvae of litomosoides carinii in sigmodon hispidus.because of the negative binomial distribution of filarial third stage larvae (l3) in their vectors, under natural conditions only a few are usually transferred per bite. after an inoculation of 5 l3 per animal into eight host animals at least one developed a long lasting patency based on one reproductive female only. after an inoculation of 15 l3, three of eight animals developed long lasting patency, harbouring between two and five fertile females. the rates of adult stages recovered were 0.43 ...19911940253
etiologic agent of lyme disease, borrelia burgdorferi, detected in ticks (acari: ixodidae) collected at a focus in alabama.the study was conducted at sites of known transmission of borrelia burgdorferi in east central alabama. the objectives were to determine species of ticks present at these sites, their host associations, and species of ticks and small mammals naturally infected with b. burgdorferi. a total of 451 hosts were examined for ticks, including cotton mice, peromyscus gossypinus (le conte); cotton rats, sigmodon hispidus say & ord; southern short-tailed shrews, blarina carolinensis (bachman); house mice, ...19911941933
in vitro cultivation of adult litomosoides carinii: evaluation of basic culture media, gas phases and litomosoides carinii, recovered from cotton rats (sigmodon hispidus) 4-5 months post-infection (p.i.), were cultivated in vitro with emphasis on investigations into the development of intra-uterine embryonic stages. baseline values for the embryonic status of female worms were established immediately after recovery from the hosts. in such females, on average, 16% of the intra-uterine stages were fully formed microfilariae while the remainder belonged to the early embryonic classes that wer ...19911945528
hispid cotton rats (sigmodon hispidus) as a source for infecting immature dermacentor variabilis (acari: ixodidae) with rickettsia rickettsii.hispid cotton rats (sigmodon hispidus say and ord) were susceptible to infection with rickettsia rickettsii wolbach under laboratory conditions and were capable of serving as sources for infecting ticks with rickettsiae. cotton rats developed rickettsemias that could be detected for as long as 6 h following intraperitoneal inoculation of 10(5) plaque-forming units (pfus) of r. rickettsii (morgan strain). an estimate of the median infectious dose (id50) was made by inoculating six groups (eight a ...19902117665
[identification of wild rodents as hosts of angiostrongylus costaricencis in southern brazil].increasing number of human cases of abdominal angiostrongyliasis has been diagnosed in the south of brazil. the main definitive host of angiostrongylus costaricensis in central america is the cotton rat (sigmodon hispidus) that does not occur in south america, except in the north of colombia, peru and venezuela. rodents were captured in the endemic area in rio grande do sul (rs) and definitive hosts were identified for the first time in brazil: oryzomys nigripes and oryzomys ratticeps. o. nigrip ...19902135366
role of early genes in pathogenesis of adenovirus pneumonia.intranasal inoculation of type 5 adenovirus into the cotton rat sigmodon hispidus produces a pneumonia pathologically similar to that in humans, and it, therefore, provides an excellent animal model to investigate the pathogenesis of this disease. the goal of this study was to test the hypothesis that accumulation of viral structural proteins is responsible for a major portion of the cell-damage-producing disease. since viral dna replication is essential for synthesis of the viral structural pro ...19902166948
strongyloidiasis in cotton rats (sigmodon hispidus) from central oklahoma.thirty-one of 40 cotton rats (sigmodon hispidus) collected from central oklahoma were infected with strongyloides sp. (78% prevalence). larvae of strongyloides sp. (rhabditiform or filariform) were not demonstrable in intestinal contents and scrapings. female nematodes recovered from intestinal contents and scrapings had morphological similarities with strongyloides sigmodontis. cotton rats infected with strongyloides sp. were indistinguishable clinically from non-infected hosts. infected animal ...19902201800
induction of hepatic cytochrome p-450 activity in wild cotton rats (sigmodon hispidus) by phenobarbital and 3-methylcholanthrene. 19892663101
hematologic and coagulation studies on cotton rats, sigmodon hispidus.1. blood coagulation factor levels and the normal ranges of commonly used coagulation tests were established for sigmodon hispidus. 2. the white cell, red cell and platelet counts have been determined together with the red cell parameters as measured by the coulter model s-plus. 3. the relationship between the results reported here and those published for related species are discussed.19872892631
serum from the cotton rat (sigmodon hispidus) lacks lytic activity against some trypanosoma vivax stocks. short communication. 19882901208
responsiveness of pineal n-acetyltransferase and melatonin in the cotton rat exposed to either artificial or natural light at three separate experiments, the effect of acute exposure to either artificial or natural light during darkness of pineal n-acetyltransferase (nat) activity and melatonin content was studied in the cotton rat (sigmodon hispidus). the exposure of animals to an artificial-light irradiance of 160,000 microw/cm2 during darkness for either 1 s, 5 s, or 30 min was followed by a precipitous decline in pineal nat activity and melatonin content when measured at either 15 or 30 min after light onset. wh ...19853007730
[the cotton rat (sigmodon hispidus) as an experimental model for studying viruses in human respiratory tract infections. i. para-influenza virus type 1, 2 and 3, adenovirus type 5 and rs virus]. 19873035295
fatal caryospora bigenetica (apicomplexa: eimeriidae) infections in cotton rats, sigmodon hispidus.four groups of cotton rats, sigmodon hispidus, were shown to be suitable secondary hosts for the viperid coccidium, caryospora bigenetica, following oral inoculation of a mixture of oocysts and sporocysts. swelling of the face, ears, and scrota and hemorrhagic ears were the predominant clinical signs and some cotton rats died in 3 of 4 experiments. developmental stages of c. bigenetica were found in connective tissue components of the ear, nose, cheeks, anal skin, scrotum, and penile sheath of a ...19883047353
spermatogenesis and ultrastructural changes of spermatids during spermiogenesis in the cotton rat, sigmodon hispidus. 19883065688
litomosoides carinii in rodents: immunomodulation in potentiating action of diethylcarbamazine.the antifilarial activity of combination of diethylcarbamazine (dec) and an immunomodulator, n-palmitoylmuramyl-l-alanyl-d-isoglutamine (np-mdp) was evaluated against litomosoides carinii in cotton rat (sigmodon hispidus) and mastomys natalensis. dec was used at 6 mg/kg in cotton rat whereas it was 75 mg/kg x 5 days in mastomys. the immunomodulator was administered at 62.5 to 500 micrograms/animal x 2 days. combination therapy with optimum dose of immunomodulator resulted in prolonged and signif ...19883075985
sarcocystis sigmodontis n. sp. from the cotton rat (sigmodon hispidus).sarcocystis sarcocysts were found in 3 of 4 cotton rats (sigmodon hispidus) from atlanta, georgia. sarcocysts were several centimetres long and were present only in skeletal muscles. the sarcocyst wall appeared thin (less than 1 micron), with minute projections in the light microscope. by transmission electron microscopy, the sarcocyst wall had 0.6-1.0 x 0.21-0.36-micron villar protrusions without microtubules. the metrocytes were 6.5 x 3.8 micron, and the bradyzoites were 8 x 2.7 micron. the sa ...19883138400
chromosomal aberrations in the cotton rat, sigmodon hispidus, exposed to hazardous waste.the study of chromosome damage in rodents living on hazardous-waste sites may provide evidence of important biological consequences of chronic exposure to toxic chemical wastes. this study compared bone-marrow cells of animals (sigmodon hispidus) taken from two superfund waste-disposal sites with those from an uncontaminated site and demonstrated that both populations exposed to hazardous wastes had significantly more structural and numerical aberrations than the control population.19883281828
[the cotton rat (sigmodon hispidus) as an experimental model for studying viruses in respiratory tract infections. ii. influenza viruses types a and b]. 19873295428
predation of cattle fever ticks by hispid cotton rats in south texas. 19873325626
effects of the two new anthelmintic agents cgp 6140 and cgp 20376 on adult paragonimus uterobilateralis in the experimental host sigmodon hispidus.the new compounds cgp 6140 and cgp 20376 were tested for their anthelmintic activity against adult paragonimus uterobilateralis in experimentally infected sigmodon hispidus. both drugs were effective at a dosage of 2 x 100 mg/kg b.w. given orally with an interval of six hours between the doses. this regimen killed 80% of the flukes collected on days 7 and 11 after treatment with cgp 6140 and 100% of the flukes collected on days 5, 7, and 11 after therapy with cgp 20376. both compounds showed no ...19873327145
fecundity of litomosoides carinii (nematoda, filarioidea) in vivo and in vitro.several parameters concerning the reproduction of litomosoides carinii were assessed using quantitatively infected cotton rats (sigmodon hispidus). the course of embryogenesis from the fertilization of eggs to the delivery of the first microfilariae was observed by daily autopsies during prepatency. the duration of embryogenesis in vivo could thus be determined as 18 +/- 2 days. the contents of embryos in the uteri of female worms had been examined at various intervals. at the onset of patency 7 ...19863515790
effect of milbemycin d against microfilariae of litomosoides carinii.the filaricidal effect of milbemycin d, a compound closely related to ivermectin, was studied in vivo and in vitro using litomosoides carinii. microfilaria (mf) densities in the peripheral blood of cotton rats, sigmodon hispidus, were reduced to less than 3% of initial densities within 24 hours after treating either subcutaneously or orally at doses of 0.05 to 50 mg/kg body weight. in cotton rats treated with diethylcarbamazine at a single dose of 200 mg/kg, mf densities were reduced transiently ...19863531647
effects of long and short photoperiod on the ultrastructure of pinealocytes of the cotton rat (sigmodon hispidus).the ultrastructure of the pinealocytes of wild-captured cotton rats (sigmodon hispidus) housed in either long or short photoperiod was examined. quantitative comparison of selected pinealocyte organelles revealed larger relative volumes of mitochondria, granular endoplasmic reticulum and ribosomes, golgi apparatus, and inclusion bodies, as well as a higher number of dense-core vesicles in the animals kept in short photoperiod (ld 8:16) as compared to those in animals kept in long photoperiod (ld ...19863537273
susceptibility of the hispid cotton rat (sigmodon hispidus) to the lyme disease spirochete (borrelia burgdorferi).the susceptibility of the hispid cotton rat, sigmodon hispidus, to the lyme disease spirochete, borrelia burgdorferi, was investigated by inoculating rats with infected tick suspensions or by allowing infected ixodes scapularis nymphs to feed on them. culture of blood samples in bsk ii medium demonstrated that cotton rats developed spirochetemias that lasted for a minimum of 3 to 4 weeks and were of sufficient concentration to infect simultaneously feeding normal i. scapularis nymphs. the spiroc ...19873688316
[potential filaricides. suramin analogs].a series of suramin analogues has been synthesized in which the methyl groups of suramin have been replaced by hydrogen, alkyl, phenyl, and fluoro substituents, or which contain more than two methyl groups. the substances have been screened against dipetalonema viteae in meriones unguiculatus, litomosoides carinii in sigmodon hispidus and l. carinii in mastomys natalensis, respectively. small structural modifications have a marked influence on the antifilarial activity. there are marked differen ...19863778551
echinococcus multilocularis: responses to infection in cotton rats (sigmodon hispidus). 19853897083
macrophage migration inhibition test of peritoneal exudate cells of litomosoides carinii-infected cotton rats by direct method in agar plate.the macrophage migration inhibition test (mit) was successfully made in agar plates using peritoneal exudate cells (pec) of cotton rats, sigmodon hispidus, during infection with litomosoides carinii. it was found that 1% bacto agar plate containing heat-inactivated serum was most suitable for the migration of pec of the cotton rat induced by liquid paraffin injection. ten percent normal cotton rat serum mixed in agar plate was best for pec migration as compared with the various concentrations of ...19853904853
experimental studies of st. louis encephalitis virus in vertebrates.serologically negative birds and mammals of species, known from other studies to be exposed naturally to st. louis encephalitis (sle) virus in memphis, tennessee, and other selected species were inoculated experimentally with strains of sle virus to determine their potential as natural hosts. mosquitoes (culex sp.) were allowed to feed on some of the inoculated vertebrate species, held for 14 days, and tested for sle infection. the cardinals (richmondena cardinalis), robins (turdus migratorius), ...19853999258
coccidia of the cotton rat, sigmodon hispidus, from alabama. 19744209629
experimental infection and intracage transmission of venezuelan equine encephalitis virus (subtype ib) among cotton rats, sigmodon hispidus (say and ord). 19744429187
copulatory behavior of cotton rats (sigmodon hispidus). 19724672558
lipofuscin distribution and histological lesions in the vitamin e deficient cotton rat (sigmodon hispidus hispidus). 19734737182
bioenergetic strategies of the cotton rat, sigmodon hispidus. 19734795625
experimental infection of the cotton rat sigmodon hispidus with rickettsia rickettsii.studies of experimental infection of the cotton rat, sigmodon hispidus, with the virulent sheila smith (r type) and the avirulent si 7 (u type) strains of rickettsia rickettsii were undertaken to evaluate the role of this native wild mammal in the ecology of rocky mountain spotted fever. the sheila smith strain, which was highly lethal for guinea pigs, was nonpathogenic for cotton rats. serial passage of the r-type strain in the cotton rat did not alter the virulence of the agent for cotton rats ...19674964475
american trypanosomiasis in british honduras. vii. a natural infection in a wild cotton rat sigmodon hispidus (rodentia, cricketidae) with a trypanosome morphologically resembling trypanosoma sigmodoni culbertson, 1941. 19694980587
social influences on exploratory behavior in the cotton rat, sigmodon hispidus. 19715167404
the chromosomes of the hispid cotton rat, sigmodon hispidus, from two localities in venezuela. 19695351757
effect of forced swimming on body temperatures and eosinophil levels in cotton rats (sigmodon hispidus). 19705425660
the filaricidal effect of basically substituted 2,6-bis-benzimidazoles in litomosoides carinii infection of the cotton rat (sigmodon hispidus). 19715575895
determination of a cobalt-60 ld50 (30) for the wild-caught cotton rat (sigmodon hispidus). 19685663791
a comparison of escape and avoidance conditioning in wild and domesticated the first of two experiments, three cotton rats (sigmodon hispidus) and three albino rats were exposed to instrumental escape, unsignaled avoidance, and signaled avoidance, in that order. all subjects learned the escape procedure quickly, with the albino rats having generally shorter latencies, higher response rates, and requiring fewer sessions to reach the criterion. when the avoidance contingency was introduced, the cotton rats continued to respond almost entirely in the presence of the sh ...19685672257
agnonistic behavior in organized and disorganized cotton rat populations.agonistic interaction rate is significantly lower in groups of caged cotton rats (sigmodon hispidus) from naturally occurring organized populations than in groups composed of strangers. some type of social structure is apparently present between animals sharing a common area under natural conditions. after a 24-hour period, there is no significant difference in the behavior of the two groups, an indication that a social structure is rapidly formed in the disorganized groups.19685689267
variation in chromosomes of the cotton rat, sigmodon hispidus. 19685722742
some developments in techniques for the study of the rodent filarial parasite litomosoides carinii. i. a preliminary comparison of the host effciency of the multimammate rat, praomys (mastomys) natalensis, with that of the cotton rat, sigmodon hispidus. 19685729256
retention of 134cs as an index to metabolism in the cotton rat (sigmodon hispidus). 19695772187
effects of acute ionizing radiation on incorporation of 131-iudr by cotton rats, sigmodon hispidus. 19695777988
american cotton rat (sigmodon hispidus) as an experimental host for brugia pahangi. 19655857267
incorporation and tissue distribution of a thymidine analog in the cotton rat sigmodon hispidus. 19676075143
a new animal model for human respiratory tract disease due to adenovirus.cotton rats (sigmodon hispidus) were tested as a model for human respiratory tract infection due to adenovirus. after intranasal instillation of 10(6.1) 50% tissue culture infectious doses (tcid50) of adenovirus type 5 into one-month-old cotton rats, groups were killed at intervals for nasal and lung titration of virus and lung histopathology. in lung, eclipse occurred at 8 hr followed by peak viral titer (10(7.5) tcid50/g of lung) on day 5. titers fell to 10(3.2) tcid50/g by day 10 and persiste ...19846086773
efficacy of aerosolized recombinant interferons against vesicular stomatitis virus-induced lung infection in cotton rats.cotton rats (sigmodon hispidus) were inoculated intranasally with vesicular stomatitis virus (vsv) and exposed to different regimens of small particle aerosols of either recombinant human alpha interferon a (rifn-alpha a) or hybrid recombinant human alpha interferon a/d (rifn-alpha a/d). preliminary in vitro tests indicated that both recombinant ifns were effective in protecting primary cotton rat pulmonary cells against vsv replication. however, rifn-alpha a/d was 20-fold more active than rifn- ...19846094681
shared antigens between litomosoides carinii and its hosts sigmodon hispidus and mastomys natalensis.using a indirect immunofluorescent technique it has been shown that host or host-like antigens are present on adults and microfilariae of litomosoides carinii from cotton rats and multimammate rats. red blood cell components were seldom detected on any stage but serum antigens were found associated with the cuticle of adults worms. serum components were absent from in utero and in vitro microfilariae but were found on microfilariae from pleural exudate and host blood. these components were lost ...19816179274
geographic variation in litter size in the cotton rat (sigmodon hispidus): factors influencing ovulation rate.litter size in many mammalian populations varies along a gradient of latitude or altitude. this investigation tested the hypothesis that geographic variation in litter size among populations of the cotton rat is the result of differences in ovulation rate. oviducts and uteri of virgin and recently mated lab-reared descendants of cotton rats from kansas (ks), texas (tx), and tennessee (tn) were flushed on the day following the last day of estrus. ovulation rates differ significantly among the thr ...19853899204
effects of nutrition on age determination using eye lens weights.populations of hispid cotton rats (sigmodon hispidus) were studied in 6 young loblolly pine (pinus taeda) plantations in south carolina, usa. each plantation had 2, 1-ha, live-trapping grids; 1 to sample a sigmodon population which continually received supplemental food, the other to sample a control population. after 15 months of live-trapping, the sigmodon were killed and their eye lenses removed, dried and weighed. birth dates were calculated for 425 sigmodon which were first captured when yo ...19863803993
unusual cytoplasmic inclusion bodies in the pinealocytes of the cotton rat (sigmodon hispidus). 19826303924
inclusion bodies in pinealocytes of the cotton rat (sigmodon hispidus). an ultrastructural study and x-ray microanalysis.pinealocytes of the cotton rat (sigmodon hispidus) often contain large (2-6 micron diameter) intracytoplasmic inclusions, the function of which is not known. these inclusions may represent nucleolus-like bodies, mineral deposits, secretory products or viral inclusions. in this study these inclusions were classified as type a, b or c inclusions based on the amount of electron-dense material interspersed within the finely granular material comprising the bulk of these inclusions. each type of incl ...19836309397
immunoglobulin administration and ribavirin therapy: efficacy in respiratory syncytial virus infection of the cotton rat.we studied the effects of combined administration of human immunoglobulin (ivig) and ribavirin aerosol on respiratory syncytial virus (rsv) infection in cotton rats (sigmodon hispidus). cotton rats assigned to receive combined therapy were administered gamimune, a preparation of purified ivig with a high titer of anti-rsv neutralizing activity, intraperitoneally 24 h prior to intranasal rsv challenge and then treated with ribavirin aerosol 3 days after challenge. lung viral titers from these cot ...19873550674
cell-mediated cytotoxic responses in lungs of cotton rats infected with respiratory syncytial virus.pneumonia induced in cotton rats (sigmodon hispidus) after inoculation of respiratory syncytial virus (rsv) was accompanied by the appearance of leukocytes in infected lungs. the number of these leukocytes increased until day 5 after inoculation when sixfold more leukocytes were recovered from infected lungs using transpleural lavage than were recovered from lungs of uninfected control animals. although macrophages and lymphocytes constituted approximately 65 and 25%, respectively, of the cells ...19836340570
effects of social environment on sexual maturation in female cotton rats (sigmodon hispidus).age at sexual maturation among female cotton rats was measured in a variety of intraspecific social environments. two experiments were conducted. in experiment i, female cotton rats attained vaginal perforation and first estrus at younger ages and lighter body masses when paired from weaning with a conspecific juvenile male than when caged alone. in experiment ii, these findings were replicated and extended. females housed with juvenile males matured at the youngest ages, while those housed alon ...19863548833
correlation of cytotoxic activity in lungs to recovery of normal and gamma-irradiated cotton rats from respiratory syncytial virus infection.cotton rats (sigmodon hispidus) that were exposed to 300, 600, or 900 rads of gamma irradiation and inoculated intranasally 2 days later with respiratory syncytial virus (rsv) exhibited prolonged virus shedding and delayed humoral and cytotoxic immune responses compared with comparably inoculated nonirradiated control rats. in nonirradiated animals and in animals exposed to 300 and 600 rads, levels of virus declined and then disappeared from the lungs during the period in which cytotoxic activit ...19836354026
distribution status of the cotton rat (sigmodon hispidus) in colorado. 19863521051
the purification and characterization of an antihemorrhagic factor in woodrat (neotoma micropus) serum.a protein antihemorrhagic factor was purified from the serum of the southern plains woodrat (neotoma micropus) by gel filtration and ion exchange chromatography. the homogeneity of the purified factor was measured by disc electrophoresis in polyacrylamide gel. the factor had an isoelectric ph of 4.1, a molecular weight of 54,000, and migrated with alpha-globulins in disc electrophoresis. the factor failed to form a precipitate with crude western diamondback rattlesnake (crotalus atrox) venom and ...19846372164
extraintestinal development of caryospora simplex (apicomplexa: eimeriidae) in experimentally infected mice, mus musculus.developmental stages of caryospora simplex were found in connective tissue of the cheek, tongue, and nose of swiss-webster and c57 bl/6 mice (mus musculus) from 8 through 70 days after oral inoculation with 50,000 or 250,000 oocysts, or 60,000 free sporocysts of the same species obtained from an ottoman viper, vipera xanthina xanthina. the earliest developmental stages were seen on day 8 post-inoculation (pi) and consisted of two types of meronts and gamonts (undifferentiated sexual stages). gam ...19846389848
the response to litomosoides carinii to antifilarial agents in cotton rat (sigmodon hispidus) & multimammate rat (mastomys natalensis). 19846394476
chromosomal aberrations in native small mammals (peromyscus leucopus and sigmodon hispidus) at a petrochemical waste disposal site: i. standard karyology. 19873314736
studies of potential filaricides: part 14--activity of 1-iso-butoxycarbonyl-4-methylpiperazine against experimental filariasis.the synthesis and filaricidal activity of 1-iso-butoxycarbonyl-4-methylpiperazine against litomosoides carinii in sigmodon hispidus and dipetalonema viteae in mastomys natalensis is reported. at an intraperitoneal or oral dose of 3 mg/kg given for 6 days, the compound removed 91% of the circulating microfilariae but had no effect on adult l. carinii. however, it killed all microfilariae and adults of d. viteae at a subcutaneous dose of 50 mg/kg given for 6 days. the compound also possessed chemo ...19846542118
field determination of 137cs assimilation efficiencies in wild cotton rats (sigmodon hispidus). 19806821541
native trichinosis in wild rodents in henrico county, virginia.encapsulated larvae of trichinella spiralis were found in wild-trapped, microtus pennsylvanicus and sigmodon hispidus. in addition, peromyscus leucopus and mus musculus again were found infected. these mammals were trapped from a farm site in henrico county, virginia, remote from known potential sources of trichinosis. the possible zoonotic relationship between wild rodent trichinosis and swine trichinosis is discussed.19807001047
new observations on first-generation merogony of eimeria tuskegeensis in sigmodon hispidus.first-generation development of eimeria tuskegeensis was evaluated using light microscopy. sporozoite-shaped meronts containing a prominent refractile body were observed in small intestinal cells of an experimentally infected cotton rat at 24 h post inoculation (pi). mature spherical or subspherical meronts containing crescent-shaped merozoites were observed at 36 h pi. refractile bodies were observed in some of these merozoites. sporozoite-shaped meronts that were isolated from host intestinal ...19873309267
litomosoides carinii infection in cotton-rats: evolution of microfilaraemia before and after treatment with diethylcarbamazine and suramin.the activity of diethylcarbamazine (dec) and suramin (s) on litomosoides carinii filariasis was assessed by the study of microfilaraemia in 30 cotton-rats (sigmodon hispidus). dec (per os) and s (injected subcutaneously) were administered alone or in combination, at doses of 50 mg/kg/day for five consecutive days. 15 rats were treated at day 91 after infection and 15 others at day 184. the immediate but temporary efficacy observed with dec was in contrast to the delayed and long-lasting effect o ...19817034313
potentiation of keystone virus infection in cotton rats by glucocorticoid-induced stress.cotton rats (sigmodon hispidus) were treated daily with corticosteroids and then inoculated with keystone virus. viremia and neutralizing antibody profiles were determined in treated and untreated rats. compared to untreated rats, the treated rats were substantially more susceptible to infection, and their viremia lasted much longer. this experimental model suggests that stress associated with excess glucocorticoid synthesis within a natural population could cause an increase in transmission of ...19827047766
pineal indoleamine metabolism in the cotton rat, sigmodon hispidus: studies on norepinephrine, serotonin, n-acetyltransferase activity and melatonin.the purpose of this study was to examine the levels of norepinephrine (ne), serotonin, melatonin and n-acetyltransferase (nat) activity in the cotton rat pineal gland in relationship to environmental lighting. in each of two experiments cotton rats were collected from the wild and housed indoors in a 14:10 light:dark (ld) cycle (lights on at 0600) for a period of at least two weeks. pineal glands were removed from animals in groups of eight at 0800, 1200, 1600, 2000, 2400, 0200 and 0400 hours ov ...19827051040
the effects of triclabendazole on the lung fluke, paragonimus uterobilateralis in the experimental host sigmodon hispidus.the new veterinary drug triclabendazole (fasinex) was tested for its anthelmintic activity against adult paragonimus uterobilateralis in experimentally infected cotton rats, sigmodon hispidus. after a single dose of 50, 100 or 150 mg/kg b.w. triclabendazole or after two doses of 5 or 10 mg/kg b.w. given at an interval of 24 hours, 56-61% of the flukes were dead at three to five weeks after treatment. two doses of 50 or 75 mg/kg b.w. triclabendazole killed all flukes. the flukes, which were still ...19883067323
tandem fusion, centric fusion, and chromosomal evolution in the cotton rats, genus sigmodon.g-banded and c-banded karyotypes of three closely related and morphologically similar species of cotton rats, sigmodon hispidus (2n=52; 52 autosomal arms), s. mascotensis (2n=28; 28 autosomal arms), and s. arizonae (2n=22,24; 38 autosomal arms) are presented and compared. despite the enormous difference between the higher diploid number of hispidus and the lower diploid numbers of mascotensis and arizonae, a great deal of g-band homology is retained. if the karyotype of hispidus is considered an ...19807389411
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