| noise stress and in vitro adrenocortical responsiveness to acth in wild cotton rats, sigmodon hispidus. | | 1978 | 210010 |
| rodent hearing: apparatus for behavioral measurements with ultrasounds. | for frequencies from 4 to 80 khz, the acoustic reliability, behavioral reliability and overall performance of an open platform were entirely satisfactory in measurements of "absolute" auditory thresholds (using a reward operant procedure) in rattus norvegicus. equal satisfaction was provided by a rodent-holder in measurements of preyer reflex thresholds over a similar frequency range in r. norvegicus, mus musculus, clethrionomys glareolus, meriones unguiculatus and sigmodon hispidus. | 1979 | 515213 |
| [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. | 1977 | 615323 |
| 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 ... | 1978 | 650786 |
| 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 ... | 1978 | 748620 |
| qualitative cranial characters distinguishing sigmodon hispidus and sigmodon arizonae and the distribution of these two species in northern mexico. | | 1978 | 750644 |
| 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 ... | 1977 | 917691 |
| endogenous stages of eimeria sigmodontis (protozoa: eimeriidae) in the cotton rat, sigmodon hispidus. | | 1977 | 924723 |
| observations on the involvement of wildlife in an epornitic of chlamydiosis in domestic turkeys. | in 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 ... | 1976 | 988009 |
| 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 ... | 1976 | 1008132 |
| elimination of 137-cs and 59-fe and its relationship to metabolic rates of wild small rodents. | elimination of 137-cs and 59-fe by three species of wild rodents was measured in laboratory and field experiments to determine whether excretion rates of these nuclides are influenced directly by general metabolic (co-2 production) rates. sigmodon hispidus and peromyscus leucopus were used in both field and laboratory experiments, and reithrodontomys humulis was investigated only in the laboratory. final-component biological half-lives (tb) of 59-fe for sigmodon averaged 108 days in winter, 144 ... | 1975 | 1133569 |
| 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 ... | 1976 | 1249916 |
| 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 ... | 1992 | 1290381 |
| 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 ... | 1992 | 1404263 |
| 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 ... | 1992 | 1548786 |
| [intestinal perforation by angiostrongylus costaricensis. a report of 2 cases]. | two cases of abdominal angiostronylosis with terminal ileum perforation are reported. the first two cases diagnosed in panama of a well established eosinophilic granulomatous process which affects mostly children in costa rica. the parasite angiostrongylus costaricensis has been demonstrated in cases with a geographic range, from mexico down to brazil. the parasite has been found in rodents in panama (sigmodon hispidus and rattus rattus) with an still pending further epidemiological and serologi ... | 1992 | 1620898 |
| 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 ... | 1991 | 1758023 |
| natural anti-snake venom proteins. | the resistance of several animals to snake venom has been reviewed. some general concepts are introduced to allow the comparative evaluation of the resistance of different animals studied by different investigators. the purification and properties of several factors isolated from the serum of different animals by some researchers are described: trimeresurus flavoviridis (omori-satoh et al., 1972); vipera palaestinae (ovadia et al., 1975, 1977); sigmodon hispidus (pichyangkul and perez, 1981); di ... | 1991 | 1801313 |
| pathogenesis of human parainfluenza virus 3 infection in two species of cotton rats: sigmodon hispidus develops bronchiolitis, while sigmodon fulviventer develops interstitial pneumonia. | human parainfluenza virus 3 replicates well in the noses and lungs of two species of cotton rats, sigmodon hispidus and sigmodon fulviventer. peak viral titers of nearly 10(6) pfu/g are reached 2 days after infection in both tissues, are maintained through day 5, and are equivalent in the two species. infectious virus is eliminated by day 8 after infection. both species produce a strong neutralizing antibody response with titers of 1:10,000 4 weeks after infection. viral replication in the nasal ... | 1991 | 1845878 |
| acute effects of benzene and cyclophosphamide exposure on cellular and humoral immunity of cotton rats, sigmodon hispidus. | | 1991 | 1863803 |
| 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 ... | 1991 | 1869357 |
| 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. | | 1991 | 1932860 |
| 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, ... | 1991 | 1941933 |
| in vitro cultivation of adult litomosoides carinii: evaluation of basic culture media, gas phases and supplements. | adult 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 ... | 1991 | 1945528 |
| 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 ... | 1990 | 2166948 |
| 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 ... | 1990 | 2201800 |
| effects of phenobarbital and 3-methylcholanthrene on the hepatic cytochrome p-450 metabolism of various alkoxyresorufin ethers in the cotton rat (sigmodon hispidus). | 1. microsomes isolated from phenobarbital and 3-methylcholanthrene induced cotton rats (sigmodon hispidus) were tested for o-dealkylase activity with methoxy-, ethoxy-, pentoxy- and benzoxyresorufin ethers. 2. the activity of 3-methylcholanthrene induced microsomes was greater than controls. 3. activity of phenobarbital induced microsomes was not different from controls. 4. there was a distinct difference between male and female animals. 5. the results obtained from cotton rats are markedly diff ... | 1989 | 2576787 |
| 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. | 1987 | 2892631 |
| serum from the cotton rat (sigmodon hispidus) lacks lytic activity against some trypanosoma vivax stocks. short communication. | | 1988 | 2901208 |
| 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 ... | 1991 | 1940253 |
| evaluation of ultrastructural hepatic response to environmental toxicants in wild cotton rats (sigmodon hispidus). | | 1991 | 1912711 |
| spermatogenesis and ultrastructural changes of spermatids during spermiogenesis in the cotton rat, sigmodon hispidus. | | 1988 | 3065688 |
| postnatal changes in nerve cells and myelinated fibers in the pineal gland of cotton rats (sigmodon hispidus). a light microscopic study. | intrapineal neurons and intracapsular and intrapineal myelinated fibers were studied by light microscopy in male cotton rats (sigmodon hispidus) at various postnatal ages. until 300 days of age, neurons are encountered mainly in the distal third of the organ; neuronal nuclei are largest in this region. the remaining regions contain only a few neurons with smaller nuclei. in all regions, nuclear sizes of the neurons increase, and neuronal numbers reduce by half until 100-200 days. neurons thus co ... | 1991 | 1760216 |
| effect of microsomal enzyme inducing agents on hepatic biotransformation in cotton rats (sigmodon hispidus): comparison to that in sprague-dawley rats. | 1. activities of several biotransformation enzymes were determined in male and female sigmodon hispidus. benzphetamine n-demethylase and glutathione s-transferases toward 1-chloro-2,4-dinitrobenzene and sulfobromophthalein were higher in male sigmodon hispidus than the female animals. 2. the study also determined the effect of microsomal enzyme inducing agents on hepatic biotransformation in male sigmodon hispidus. 3. cytochrome p-450 concentration was similar in cotton and sprague-dawley rats, ... | 1991 | 1676957 |
| 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 ... | 1988 | 3138400 |
| behavioral response of altricial and precocial rodent fetuses to acute umbilical cord compression. | norway rat fetuses (rattus norvegicus) exhibit a stereotypic behavioral response when the umbilical cord is experimentally compressed with a vascular clamp. in this study, the development of the fetal behavioral response to cord compression was compared in altricial and precocial rodents, which differ markedly in neural and motor maturity at the time of birth. both altricial and precocial species showed some form of behavioral response to umbilical cord compression. fetuses of two altricial spec ... | 1992 | 1586357 |
| [the cotton rat (sigmodon hispidus) as an experimental model for studying viruses in respiratory tract infections. ii. influenza viruses types a and b]. | | 1987 | 3295428 |
| 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 ... | 1992 | 1528912 |
| chromosomal aberrations in native small mammals (peromyscus leucopus and sigmodon hispidus) at a petrochemical waste disposal site: i. standard karyology. | | 1987 | 3314736 |
| predation of cattle fever ticks by hispid cotton rats in south texas. | | 1987 | 3325626 |
| 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 ... | 1992 | 1512870 |
| 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 ... | 1986 | 3515790 |
| 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 ... | 1975 | 1097743 |
| immunoprophylaxis with bcg of experimental echinococcus multilocularis infections. | previous studies have demonstrated that prophylactic treatment with bcg protects cotton rats (sigmodon hispidus) against experimental infections with echinococcus multilocularis; this treatment can, however, induce granulomatous reactions. in an attempt to identify a minimum prophylactic dose of bcg which would not induce granulomas, cotton rats were treated intraperitoneally with various doses of bcg (10(1) to 10(7) colony-forming units [cfu]) and then inoculated intraperitoneally with one broo ... | 1978 | 711311 |
| 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 ... | 1986 | 3537273 |
| 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 ... | 1978 | 646022 |
| 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 ... | 1987 | 3550674 |
| 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 ... | 1987 | 3688316 |
| [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 ... | 1986 | 3778551 |
| 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 ... | 1986 | 3803993 |
| echinococcus multilocularis: responses to infection in cotton rats (sigmodon hispidus). | | 1985 | 3897083 |
| field studies of systemic insecticides. iv. evaluation of phoxim for prevention of natural seasonal increases of fleas on the hispid cotton rat. | | 1977 | 609076 |
| photoperiodic influences on gonadal development and maintenance in the cotton rat, sigmodon hispidus. | | 1979 | 486631 |
| 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), ... | 1985 | 3999258 |
| coccidia of the cotton rat, sigmodon hispidus, from alabama. | | 1974 | 4209629 |
| experimental infection and intracage transmission of venezuelan equine encephalitis virus (subtype ib) among cotton rats, sigmodon hispidus (say and ord). | | 1974 | 4429187 |
| copulatory behavior of cotton rats (sigmodon hispidus). | | 1972 | 4672558 |
| lipofuscin distribution and histological lesions in the vitamin e deficient cotton rat (sigmodon hispidus hispidus). | | 1973 | 4737182 |
| bioenergetic strategies of the cotton rat, sigmodon hispidus. | | 1973 | 4795625 |
| 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 ... | 1967 | 4964475 |
| 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. | | 1969 | 4980587 |
| social influences on exploratory behavior in the cotton rat, sigmodon hispidus. | | 1971 | 5167404 |
| radiocesium uptake by a population of cotton rats (sigmodon hispidus) inhabiting the banks of a radioactive liquid waste pond. | | 1979 | 422372 |
| effect of forced swimming on body temperatures and eosinophil levels in cotton rats (sigmodon hispidus). | | 1970 | 5425660 |
| the filaricidal effect of basically substituted 2,6-bis-benzimidazoles in litomosoides carinii infection of the cotton rat (sigmodon hispidus). | | 1971 | 5575895 |
| ultrastructure of pinealocytes of the cotton rat, sigmodon hispidus. | fine structural features of pinealocytes of cotton rats (sigmodon hispidus) were examined. golgi complexes, mitochondria, endoplasmic reticulum and polysomes are usual organelles seen in the perikaryonal cytoplasm of pinealocytes. many non-granulated vesicles (40 to 80 nm in diameter) and a few granulated vesicles (about 100 nm in diameter) are associated with the golgi cisternae. occasionally, the cisternae contain granular materials. the perikaryonal cytoplasm of pinealocytes is characterized ... | 1979 | 230906 |
| an evaluation of the zygomatic arch for separating juvenile from adult cotton rats (sigmodon hispidus). | | 1975 | 167088 |
| 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. | 1968 | 5689267 |
| variation in chromosomes of the cotton rat, sigmodon hispidus. | | 1968 | 5722742 |
| the role of the tail in temperature regulation of the cotton rat, sigmodon hispidus. | | 1975 | 1200 |
| 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 ... | 1990 | 2117665 |
| [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 ... | 1990 | 2135366 |
| [light microscopic observations on intrapineal neurons and myelinated fibers distributed in the pineal gland and its capsule in cotton rats (sigmodon hispidus) at various postnatal ages]. | from birth to 300 days, neurons are mainly encountered in the distal third of the pineal gland. neurons are scarce in the middle or proximal third; their number is fewer in the proximal third. nuclear size of neurons in all pineal regions increases until 100-200 day. since there are regional differences in size of nuclei of intrapineal neurons in cotton rats until 200 days, intrapineal neurons of this animal may be composed of different populations of cells. the observation that age changes in s ... | 1990 | 2227798 |
| susceptibility of wild mammals to infection with naegleria fowleri. | animals of 4 families of small wild mammals were live-trapped and inoculated intranasally with naegleria fowleri to determine patterns of susceptibility. of the 7 species of animals examined, only rodents were susceptible to n. fowleri. susceptible animals were eastern gray squirrel, hispid cotton rat, muskrat, and house mouse. mammals that were not susceptible at a dose of 10(6) were opossum, raccoon, and eastern cottontail rabbit. perhaps rodents and humans share a common anatomical or physiol ... | 1990 | 2254821 |
| development of the cotton rat (sigmodon hispidus) as a biomonitor of environmental contamination with emphasis on hepatic cytochrome p-450 induction and population characteristics. | | 1989 | 2653475 |
| induction of hepatic cytochrome p-450 activity in wild cotton rats (sigmodon hispidus) by phenobarbital and 3-methylcholanthrene. | | 1989 | 2663101 |
| role of early region 3 (e3) in pathogenesis of adenovirus disease. | the cotton rat sigmodon hispidus has provided an animal model of adenovirus pneumonia that permits investigation of the viral gene products required to produce the disease and the molecular mechanisms effecting the damage. this study was carried out to test the hypothesis that early region 3 (e3) of the adenovirus genome plays a critical role in pathogenesis of the virus's disease process even though none of its gene products are essential for its replication. mutants whose e3 region is largely ... | 1989 | 2726753 |
| responsiveness of pineal n-acetyltransferase and melatonin in the cotton rat exposed to either artificial or natural light at night. | in 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 ... | 1985 | 3007730 |
| [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]. | | 1987 | 3035295 |
| 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 ... | 1988 | 3047353 |
| 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 ... | 1988 | 3067323 |
| 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 ... | 1988 | 3075985 |
| 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. | 1988 | 3281828 |
| 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 ... | 1987 | 3309267 |
| 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 ... | 1987 | 3327145 |
| distribution status of the cotton rat (sigmodon hispidus) in colorado. | | 1986 | 3521051 |
| 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 ... | 1986 | 3531647 |
| 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 ... | 1986 | 3548833 |
| 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 ... | 1985 | 3899204 |
| 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 ... | 1985 | 3904853 |
| the chromosomes of the hispid cotton rat, sigmodon hispidus, from two localities in venezuela. | | 1969 | 5351757 |
| determination of a cobalt-60 ld50 (30) for the wild-caught cotton rat (sigmodon hispidus). | | 1968 | 5663791 |
| a comparison of escape and avoidance conditioning in wild and domesticated rats. | in 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 ... | 1968 | 5672257 |
| 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. | | 1968 | 5729256 |
| retention of 134cs as an index to metabolism in the cotton rat (sigmodon hispidus). | | 1969 | 5772187 |
| effects of acute ionizing radiation on incorporation of 131-iudr by cotton rats, sigmodon hispidus. | | 1969 | 5777988 |
| american cotton rat (sigmodon hispidus) as an experimental host for brugia pahangi. | | 1965 | 5857267 |
| incorporation and tissue distribution of a thymidine analog in the cotton rat sigmodon hispidus. | | 1967 | 6075143 |
| 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 ... | 1984 | 6086773 |
| 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- ... | 1984 | 6094681 |