experimental transmission of sarcocystis from icterid birds to sparrows and canaries by sporocysts from the opossum.cowbirds (molothrus ater) and grackles (cassidix mexicanus) infected with muscle cysts of sarcocystis were fed to opposums (didelphis virginiana) and fecal sporocysts from the latter were given to sparrows (passer domesticus, family ploceidae), canaries (serinus canarius, family fringillidae) and ducks (anas platyrhynchos, family anatidae). asexual parasites were found in the endothelium of sparrows and canaries but not in ducks. when birds were kept 10 weeks or more after infection, muscle cyst ...197898622
biosynthesis and secretion of testosterone by adrenal tissue from the north american opossum, didelphis virginiana, and the effects of tropic hormone stimulation. 1975173619
the opossum (didelphis virginiana) as a host for sarcocystis debonei from cowbirds (molothrus ater) and grackles (cassidix mexicanus, quiscalus quiscula).sarcocystis-infected muscles from ducks, cowbirds, and grackles were fed to cats, opossums, rats, and a dog. only the opossum (didelphis virginiana) was a suitable definitive host. all opossums that were fed sarcocystis-infected cowbirds (molothrus ater) and grackles (cassidix mexicanus and quiscalus quiscula) passed sporocysts in their feces. opossums that ate the cowbirds had prepatent periods of 5 and 10 days and remained patent for at least 105 days. opossums that ate the grackles became pat ...1978417165
dipetalonema (acanthocheilonema) didelphis sp. n. (nematoda: filarioidea) from opossums, with a redescription of d. (a.) pricei (vaz and pereira 1934).dipetalonema (acanthocheilonema) didelphis sp. n. recovered from the subcutaneous and periesophageal connective tissues of didelphis virginiana from several localities in the united states and of d. marsupialis from colombia is described. dipetalonema didelphis sp. n. resembles d reconditum and d. mansonbahri in size, in lacking a two-segmented buccal capsule, and in the female having a long, digitiform tail. dipetalonema reconditum, however, has a much longer glandular esophagus and d. mansonba ...1979575550
primary isolation of mycobacterium avium complex-serotype 6 on blood agar.mycobacterium avium complex-serotype 6 was isolated in pure culture on blood agar plates from inocula taken from the heart blood, lungs, liver, kidneys, and spleen of a naturally infected captive female opossum (didelphis marsupialis virginiana). repeat cultures from stored tissues and transfer of colonies from original blood agar plates revealed that the mycobacterium grew on tryptose, brilliant green, eosin-methylene blue. sabouraud glucose, and mycobiotic agar plates and in fletcher leptospir ...1976972192
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
electrocardiographic and echocardiographic features of trypanosomiasis in dogs inoculated with north american trypanosoma cruzi isolates.purebred beagles were inoculated with trypanosoma cruzi isolates from a north american opossum or armadillo (tc-w), and dog (tc-d). although tc-d established infection in dogs, the dogs did not develop cardiac abnormalities. dogs inoculated with tc-w developed acute myocarditis associated with increases in p-r interval, atrioventricular block, depression of r wave amplitude and shifts in mean electrical axis. echocardiograms were normal during this stage. three tc-w-inoculated dogs died during t ...19921586022
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 ...19911801313
hypertrophic smooth muscle in the partially obstructed opossum esophagus. the model: histological and ultrastructural observations.obstruction is a complication of many esophageal diseases, but the morphological changes occurring in the obstructed esophagus are poorly understood. we developed a model of esophageal obstruction in the american opossum, didelphis virginiana. a nonconstricting band around the gastroesophageal junction led to esophageal distention and tortuosity in the weeks following its placement. despite a marked increase of the esophageal circumference, the esophageal wall was not thinned, and the circular m ...19912001825
host-dependent differences in feeding and reproduction of ixodes dammini (acari: ixodidae).the frequencies with which adult ixodes dammini spielman, clifford, piesman and corwin feed upon white-tailed deer (odocoileus virginianus), raccoons (procyon lotor), opossums (didelphis virginiana), and domestic cats were compared in a wooded site in northeastern united states. by combining estimates of the quantity of ticks feeding on each host species with host densities, we derived the relative contribution made by each kind of host to the feeding of the tick population. to compare engorgeme ...19902280395
the lamina propria of vertebrate seminiferous tubules: a comparative light and electron microscopic investigation.the lamina propria of the seminiferous tubules was compared by means of light and electron microscopy in specimens obtained from the following vertebrates: mute swan, northern mallard, blackbird, grey short-tailed opossum, north american opossum, european rabbit, mouse, rat, golden hamster, mini pig, bull, llama, roebuck, horse, coati, cat, dog, java monkey, orang utan. the lamina propria consists of basal lamina, ground substance, collagen fibers, fibroblasts and myofibroblasts. myofibroblasts ...19902281881
aerobic bacteria cultured from the mouth of the american opossum (didelphis virginiana) with reference to bacteria associated with bite infections.the american opossum inflicts bite injuries both when hunted for food and when accidentally provoked when handled in captivity. this study involved aerobically culturing organisms from the mouths of seven wild opossums (didelphis virginiana). isolates included streptococci, coagulase-positive and -negative staphylococci, aeromonas spp., citrobacter freundii, eikenella corrodens, and escherichia coli.19902229365
autoradiographic demonstration of specific binding sites for e. coli enterotoxin in various epithelia of the north american the north american opossum, heat-stable specific binding sites for e. coli enterotoxin are observed (i) in epithelial cells lining the small intestine, colon, gall bladder, cystic duct, common bile duct and trachea, and (ii) in epithelial cells forming the duodenal (brunner's) glands, liver, kidneys (metanephros, mesonephros) and testis, as demonstrated by autoradiography. enterotoxin-specific binding sites in the intestinal tract are only found in intestinal epithelial cells with the highest ...19902162736
effects of hydrocortisone acetate treatment on the small intestine of the lactent marsupial didelphis albiventris.when hydrocortisone acetate was administered subcutaneously to the lactent brazilian white belly opossum, it induced precocious intestinal maturation. histological features of the small intestine were reminiscent of those seen in human protein-caloric malnutrition. there were also indications that the glucocorticoid acted as an inducer of the differentiation of paneth, goblet and granulomucous cells within the small intestinal epithelium. in the lactent opossum the small intestine is lined by an ...19912064018
the role of medium-sized mammals as reservoirs of borrelia burgdorferi in southern new york.the ability of raccoons (procyon lotor), striped skunks (mephitis mephitis) and opossums (didelphis virginiana) to serve as reservoirs of borrelia burgdorferi, the spirochetal agent of lyme disease, was compared with that of white-footed mice (peromyscus leucopus). twenty-eight (28) medium-sized mammals and 34 white-footed mice were captured in westchester county, new york (usa) in summer 1986. animals were caged over pans of water for 1 to 2 days to recover engorged tick larvae (ixodes dammini) ...19902388356
a pharmacological study of oesophageal muscularis mucosae from the cat, dog and american opossum (didelphis virginiana). addendum. 19852411325
lung lesions in an opossum (didelphis virginiana) associated with capillaria opossum (didelphis virginiana) live-trapped on parramore island, virginia was infected with the lung parasite capillaria didelphis. lung lesions associated with this parasite were extensive and consisted of numerous areas with central necrosis deep within the parenchyma. necrotic foci were present around airways and consisted of a mixture of inflammatory cells and cellular debris, adult nematodes and many bipolar eggs. this parasite causes severe verminous pneumonia in the opossum.19912023321
characterization of the muscarinic cholinergic receptor in the opossum (didelphis virginiana, kerr) submandibular gland: differences in receptor density and subtype compared with higher mammalian species.1. kinetic, saturation and inhibition radioligand binding experiments with [3h]-n-methylscopolamine and [3h]quinuclidinyl benzilate were used to characterize the muscarinic cholinergic receptor in opossum (didelphis virginiana, kerr) submandibular salivary gland membranes. 2. the receptor density in opossum submandibular gland was found to be more than 3-fold higher than in rat, and 22-fold higher than in human, submandibular glands. 3. inhibitor equilibrium dissociation constants for the antago ...19901981346
deoxyadenosine triphosphate acting as an energy-transferring molecule in adenosine deaminase inhibited human erythrocytes.deoxyadenosine triphosphate (datp) is present in adenosine deaminase (ada)-deficient or ada-inhibited human red cells and in the red cells of the opossum didelphis virginiana. in order to investigate the functions of datp in the red cell, red cells were treated with 2'-deoxycoformycin (dcf), a powerful inhibitor of ada, and incubated with phosphate, deoxyadenosine and glucose. these red cells in which atp was almost completely replaced by datp, had the same shape, lactate production, nucleotide ...19911911876
salmonella infection of the biliary and intestinal tract of wild opossums.bacteriologic cultures were taken from the mesenteric lymph nodes, biliary tract, blood, liver, spleen and pancreas of opossums (didelphis virginiana) obtained directly from the wild for use as research animals. the overall incidence of salmonellosis outside the intestinal tract was 61% among 18 opossums. salmonella was recovered from the gallbladder of six (33%) animals, indicating chronic biliary tract infection. among these six animals, translocation of salmonella to regional lymph nodes was ...19911849588
immunohistochemical study of the developing endocrine pancreas of the opossum (didelphis virginiana).cells immunoreactive for insulin, glucagon, somatostatin, bovine pancreatic polypeptide and 5-hydroxytryptamine are found in the pancreas of the newborn opossum and of all later stages examined. all immunoreactive cell types are present in primary and secondary islets and within elements of the exocrine pancreas. cells immunoreactive for glucagon, bovine pancreatic polypeptide, somatostatin and 5-hydroxytryptamine generally are confined to the periphery of secondary (intralobular) islets, wherea ...19892665414
organization of midbrain catecholamine-containing nuclei and their projections to the striatum in the north american opossum, didelphis virginiana.presumptive catecholamine (ca) neurons in the opossum midbrain were identified by tyrosine hydroxylase immunohistochemistry. in the midline, small to moderate number of ca cells were present in the rostral third of the nucleus raphe dorsalis and throughout the nucleus linearis. ventrolaterally, such cells were observed in the deep tegmental reticular formation, in all subnuclei of the ventral tegmental area, and in the three subdivisions of the substantia nigra. the ca cells in these areas confo ...19911677010
host associations of ticks (acari: ixodidae) parasitizing medium-sized mammals in a lyme disease endemic area of southern new york.ticks of eight medium-sized mammal species were studied in an area of endemic lyme disease in westchester county, n.y., from 1 april 1984 to 31 march 1985. most (81%) of the 266 total mammal captures were raccoon, procyon lotor (l.) (47%), opossum, didelphis virginiana (kerr) (19%), and striped skunk, mephitis mephitis schreber (15%); these host species accounted for 91% of the 1,519 ticks collected. although the total number of ticks was rather evenly distributed among these mammals, species co ...19892724317
serologic response of the opossum didelphis virginiana to a temperature-sensitive mutant (ts-4) of toxoplasma gondii.a study was designed to measure the toxoplasma gondii-specific igm and igg antibody responses of opossums inoculated with tachyzoites of the temperature-sensitive mutant of t. gondii, ts-4, and to examine its persistence in the tissues. four young opossums seronegative for anti-toxoplasma gondii igm and igg antibodies immediately after capture and 4 wk later were injected subcutaneously with 1.8 x 10(6) ts-4 tachyzoites; a fifth opossum (also seronegative) received an injection of saline only. s ...19921635036
retinal topography in the koala (phascolarctos cinereus).nissl-stained retinal wholemounts were used to investigate the topographical organization of the ganglion cell layer of the koala (phascolarctos cinereus); the visual resolution limit of this animal was subsequently estimated from retinal ganglion cell density data. two types of cells could be differentiated on the basis of their size and staining characteristics: a subpopulation of presumed ganglion cells, consisting of medium to large cells with nissl substance in the cytoplasm and pale unifor ...19921537048
oral vaccination of raccoons (procyon lotor) with an attenuated (sad-b19) rabies virus vaccine.unlike previous reports to the contrary, raccoons (procyon lotor) were successfully vaccinated against rabies with a liquid sad-b19 attenuated virus vaccine administered per os and given in vaccine-laden baits. there was neither evidence of vaccine-induced rabies in raccoons nor in a limited safety trial with opossums (didelphis virginiana) given sad-b19. protection from lethal street rabies virus infection was not absolute: only three of nine raccoons given 1 x 10(6.0) tcid/ml were protected ve ...19892810555
immunohistochemical localization of relaxin in the reproductive system of the female opossum (didelphis virginiana).relaxin-immunoreactivity was demonstrated in the cytoplasm in the luteal cells from pregnant and lactating opossums. immunoreactivity for relaxin was not demonstrated elsewhere in the ovary, in the reproductive tract or in the placenta. the corpus luteum is thought to be the primary source of relaxin in didelphis and in this regard is similar to several eutherian mammals including man.19921416066
receptors and cgmp signalling mechanism for e. coli enterotoxin in opossum kidney.receptors for the heat-stable enterotoxin produced by escherichia coli were found in the kidney and intestine of the north american opossum and in cultured renal cell lines. the enterotoxin markedly increased guanosine 3',5'-cyclic monophosphate (cgmp) production in slices of kidney cortex and medulla, in suspensions of intestinal mucosa, and in the opossum kidney (ok) and rat kangaroo kidney (ptk-2) cell lines. in contrast, atrial natriuretic factor elicited much smaller increases in cgmp level ...19882847547
corticobulbar fibres in the north american opossum (didelphis marsupialis virginiana) with notes on the tasmanian brust-tailed possum (trichosurus vulpecula) and other marsupials.corticobulbar projections have been studied in the american opossum by both degeneration and autoradiographic methods and, for the most part, the results confirm our earlier observations (martin & west, 1967; martin, 1968). however, we have obtained evidence for certain connexions not previously described and have delineated the origin(s) of several connexions more precisely by paying particular attention to the degeneration present at thalamic levels in all cases and by the use of autoradiograp ...19751213949
leptospirosis in wildlife in brazil: isolation of a new serotype in the pyrogenes group.a new leptospiral serotype in the serogroup pyrogenes is described. the strain was isolated from one gray "four-eyed" opossum (philander opossum). it is proposed that the serotype be designated guaratuba, strain an-7705. the isolations of serotypes ballum from the south american field mouse (akodon arviculoides), szwajizak and icterohaemorrhagiae from the north american opossum (didelphis marsupialis), and grippotyphosa from many other wild animal species as well as domesticated animals are also ...19751163877
the inferior olivary nucleus of the opossum (didelphis marsupialis virginiana), its organization and connections.although the inferior olivary nucleus of the opossum is small, sections stained either for nissl substance, normal axons or cholinesterase activity reveal distinct medial, dorsal and principal nuclei. the medial nucleus contains three major subdivisions (labelled a, b, c after bowman and sladek, '73) and a group of neurons which is comparable to the cap of kooy. in contrast to the cat and monkey, the major portion of the "medial" nucleus (subgroup a) lies lateral to the principal nucleus in rost ...19751123465
proteolytic, hemorrhagic and hemolytic activities of snake venoms.proteolytic, hemorrhagic and hemolytic activities were tested on 47 different venoms from the crotalidae, viperidae, elapidae, and hydrophiidae families. antihemorrhagic activity of crude opossum (didelphis virginiana) and woodrat (neotoma micropus) serum was tested against the venoms that presented hemorrhagic activity. all venoms showed proteolytic activity when non-specific substrates such as hide powder and collagen were used. members of the crotalidae family had the highest hide powder, chy ...19883059584
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
the amino-acid sequence of the alpha-crystallin a chains of red kangaroo and virginia opossum.the amino acid sequence of the a chain of the eye lens protein alpha-crystallin from the red kangaroo (macropus rufus) was completely determined by manual edman degradation of tryptic, thermolytic and cyanogen bromide peptides. the sequence of the alpha-crystallin a chain from the virginia opossum (didelphis marsupialis) was deduced from amino acid analyses and partial edman degradation of peptides. the 173-residue a chains of kangaroo and opossum differ in six positions, whereas comparison with ...1976964255
the vestibular complex of the american opossum, didelphis virginiana. i. conformation, cytoarchitecture and primary vestibular input.degeneration experiments reveal that the vestibular nerve of the adult opossum distributes to an extensive and diverse area of the brainstem and, as in placental mammals, the traditionally named nuclei do not receive a uniform distribution of primary afferent fibers. nevertheless, such nuclei as well as other nearby cell groups have been considered as vestibular since they share other mutual connections. except for subgroups "l", "g" and the nucleus supravestibularis all of the vestibular subdiv ...1977838884
an immunohistochemical survey of gastric proteinase (pepsinogen and prochymosin)-containing cells in the stomach of the developing opossum (didelphis virginiana).cells immunoreactive to antisera of bovine pepsinogen and prochymosin are seen in the oxyntic glands but not the pyloric or cardiac glands of the opossum. immunoreactivities to pepsinogen and prochymosin occur within the same cell and are restricted to an undifferentiated cell type prior to weaning. the undifferentiated cells producing these gastric proteinases decrease in number until just prior to weaning and disappear with the appearance of chief cells. thereafter, immunoreactivities to both ...19873128513
frequency of sarcocystis spp in detroit, metropolitan area, michigan.a survey of sarcocystis spp in feral animals and in domesticated animals slaughtered in detroit, mi, was undertaken during a 6-month period, april to september, 1973, using histologic and digestion diagnostic techniques. results indicated 75.3% of 789 sheep and 10.8% of 306 lambs were infected. infection in young and adult sheep was low in april (0% of 78 lambs and 6.7% of 62 adult sheep), but increased in july (24% of 90 lambs and 94.1% of 201 adult sheep). high frequency of sarcocystis in summ ...1975803806
the organization of olivo-cerebellar projections in the opossum, didelphis virginiana, as revealed by the retrograde transport of horseradish peroxidase.the retrograde transport of horseradish peroxidase was utilized to map olivo-cerebellar projections in the virginia opossum. the spinal cerebellum (anterior lobe, paramedian lobule and pyramis) receives input from several separate regions in the dorsal accessory nucleus, the medial accessory nucleus and portions of the principal nucleus. evidence is present for a topographical organization whereby specific regions of the olive project to restricted longitudinal zones. the visual-auditory region ...1978641222
differential distribution of the p1 and p2 protamine gene sequences in eutherian and marsupial mammals and a the protein level, the p1 protamine is the predominant form of mammalian protamine, present in all mammalian spermatozoa analyzed to date. an additional variant, the p2 protamine, has been detected only in spermatozoa of the mouse, hamster and human. southern blot analysis of a group of restriction enzyme-digested mammalian dnas has revealed the presence of sequences homologous to the p1 and p2 mouse protamine genes in diverse species. in agreement with protein studies, nucleotide sequences h ...19883209180
localization of g6pd and hprt to different arms of the x chromosome of the north american marsupial (didelphis virginiana) by in situ hybridization and deletion mapping: evolutionary significance.we have mapped hprt and g6pd loci on the x chromosome in the american opossum, didelphis virginiana, by in situ hybridization to cells derived from two females by using genomic opossum dna as probes. the localizations (g6pd to xp13 and hprt to xq21), indicating that the two genes are separated by the centromere, were confirmed by results of hybridization to x chromosomes with deletions that include the hprt locus and opossum-mouse cell hybrids containing the relevant fragment of the opossum x ch ...19883243545
experimental cryptosporidium parvum infections in opossums (didelphis virginiana).five nursing opossums (didelphis virginiana) were each inoculated with 5 x 10(6) cryptosporidium parvum oocysts of calf origin. following inoculation, endogenous stages of c. parvum were observed in the ileum, cecum, and colon of these opossums. two of three noninoculated pouch mates acquired infections during the study based on examinations of feces and tissue sections of all eight opossums. mild diarrhea was observed in four of seven opossums harboring c. parvum, although none died as a result ...19883352085
spinal projections from the mesencephalic and pontine reticular formation in the north american opossum: a study using axonal transport techniques.the results from several experimental approaches lead to the following conclusions. the nucleus cuneiformis projects to at least lumbar levels of the spinal cord. its axons course through the ipsilateral sulcomarginal and ventral funiculi to distribute within lamina viii and adjacent portions of lamina vii. neurons within the nucleus reticularis pontis (rp), particularly within more medial parts of the nucleus, project through comparable routes to the same laminae. in addition, however, neurons ...1979489785
the vestibular complex of the american opossum didelphis virginiana. ii. afferent and efferent connections.we have demonstrated the connectivity of the opossum's vestibular nuclei using degeneration, autoradiographic and horseradish peroxidase techniques and have found it to be generally comparable to that reported for the cat. apart from the primary input described in part i of our study, the cerebellum provides the major source of afferent connections to the vestibular complex. axons from the cerebellar cortex distribute mainly to vestibular areas which receive no primary afferent projections, e.g. ...197765367
lyme disease ecology in wisconsin: distribution and host preferences of ixodes dammini, and prevalence of antibody to borrelia burgdorferi in small mammals.lyme disease recently has been recognized in wisconsin. trapping studies were conducted at four geographically separate and ecologically distinct regions in wisconsin to elucidate the distribution and host preferences of ixodes dammini on small and medium sized mammals, and the occurrence of antibodies to borrelia burgdorferi in these wild mammals. peak i. dammini larval activity occurred from june-september. nymphs were most active from may-august. white-footed mice (peromyscus leucopus) and ch ...19873605501
the development of commissural connections of somatic motor-sensory areas of neocortex in the north american opossum.the north american opossum does not have a corpus callosum; neocortical commissural axons are contained entirely within the anterior commissure. we have used axonal transport techniques to study the origin and distribution of commissural axons from somatic motor-sensory cortex in developing and adult opossums. neocortical axons grow into the anterior commissure by postnatal day (pnd) 12, the contralateral external capsule by approximately pnd 19, the area deep to the contralateral homotypic cort ...19853838629
tactile cutaneous representation in cerebellar granule cell layer of the opossum, didelphis virginiana.recent studies of the albino rat revealed extensive cutaneous somatosensory projections to the granule cell (gc) layer of the cerebellar hemispheres and the caudal vermis. these projections are organized asomatotopically in patchy mosaics. to determine whether similar projections exist in a marsupial, we explored the gc layer of the cerebellar cortex of anesthetized virginia opossums using in-depth microelectrode micromapping and juxtathreshold cutaneous natural stimulation techniques. we found: ...19853843070
opossum (didelphis virginiana) "little" and "big" gastrins.1. "little" gastrins from most mammalian species are 17 amino acid peptides and the precursor "big" gastrins are 34 amino acid peptides. 2. "little" gastrins of the new world hystricomorphs, guinea-pig and chinchilla, are 16 amino acid peptides due to deletion of a glutamic acid in the region 6-9 from their nh2-terminus and the corresponding "big" gastrins are 33 amino acid peptides. 3. antral gastrins from the opossum, a new world marsupial, have a glutamic acid deletion in the same region as t ...19902361360
brucella abortus in wildlife on selected cattle farms in alabama.two studies of brucellosis in wildlife on farms where the brucellosis infection prevalence in cattle was known are reported. on a research farm, 233 feral animals of 22 mammalian species and 12 of seven avian species were trapped during three time periods. sixty were studied before cattle were introduced, 128 were studied while 501 cattle infected with brucella abortus were calving and aborting, and 60 specimens were collected 20 mo after the last infected cow calved. selected tissues from 229 w ...19853923213
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
vascular and avascular retinae in mammals. a funduscopic and fluorescein angiographic study.intraretinal blood vessels are present in some and absent in other vertebrate species, including the mammals. among the marsupials, both vascular and avascular retinae are seen. we determined the funduscopic appearance of the eye, investigated the functional aspects of ocular blood flow in both types of retina in marsupials and compared our results with known patterns in placental mammals. the australian polyprotodont marsupials, the tasmanian devil, sarcophilus harrisii, and the quoll, dasyurus ...19902375974
ectoparasitic and phoretic arthropods of virginia opossums (didelphis virginiana) in central tennessee.thirteen species of ectoparasitic (12) or phoretic (1) arthropods were collected from 26 adult virginia opossums, didelphis virginiana, live-trapped from april through september 1987 in davidson county, tennessee. the cat flea ctenocephalides felis and the american dog tick dermacentor variabilis were the predominant species with respect to mean intensity and prevalence. the macronyssid mite ornithonyssus wernecki and the atopomelid mite didelphilichus serrifer, both specific parasites of this h ...19902380870
the distribution of photoreceptors, dopaminergic amacrine cells and ganglion cells in the retina of the north american opossum (didelphis virginiana).quantitative light microscopic techniques have been applied to photoreceptors, ganglion cells and dopaminergic amacrine cells in the retina of the north american opossum didelphis virginiana. this marsupial has a retina with a central areal specialization where ganglion cells reach a maximum density of 2900/mm2 and cone photoreceptors are concentrated. however, the retina is very much rod dominated and there is a ring of peak rod density approximately 2 mm around the area centralis (a.c.). at th ...19854072000
acquired immunity in opossum (didelphis virginiana) embryos. 19744133078
the immunologic responses of the north american opossum (didelphys virginiana). 19684177528
pulmonary adenomatosis in opossums (didelphis virginiana). 19694310335
pasteurella multocida infection in the opossum (didelphis virginiana). 19744374598
morphology of neuroglia in the hypothalamus of the opossum (didelphis virginiana), armadillo (dasypus novemcinctus mexicanus) and cat (felis domestica). 19714944389
experimental bacterial endocarditis in the opossum (didelphis virginiana). 3. comparison of spontaneously occurring endocarditis with that induced experimentally by pyogenic bacteria and was possible to induce bacterial endocarditis in opossums with single intravenous injections of streptococcus viridans or staphylococcus aureus. fiftyeight percent of those animals given streptococcus viridans developed bacterial endocarditis in which most of the lesions were on the left side of the heart. the experimentally induced streptococcal disease was similar to that which may occur spontaneously in opossums, both with respect to the distribution and structure of the vegetations. singl ...19715133514
the immune response of adult opossums (didelphis virginiana) to the bacteriophage f2. 19705416636
experimental bacterial endocarditis in the opossum (didelphis virginiana). ii. induction of endocarditis with a single injection of streptococcus viridans. 19705433712
experimental bacterial endocarditis in the opossum (didelphis virginiana). i. valvular changes following a single injection of bacteria in unmodified adult opossums. 19705437267
origin of mammalian thalamocortical projections. i. telencephalic projections of the medial geniculate body in the opossum (didelphis virginiana).telencephalic projections from the medial geniculate nucleus (mg) in opossum were traced with tritiated leucine autoradiography and by horseradish peroxidase and fluorescent dye retrograde labeling techniques. the results show that the opossum's mg contains two separate populations of neurons-one in the anterior two-thirds of mg projecting to auditory neocortex, the other occupying the entire caudal one-third of mg and projecting mostly to lateral amygdala and putamen. because the subcortical pr ...19862420841
a cytoarchitectonic atlas of the medial geniculate body of the opossum, didelphys virginiana, with a comment on the posterior intralaminar nuclei of the thalamus.the organization of the medial geniculate body and adjacent posterior thalamus of the virginia opossum was studied in nissl-, golgi-, reduced silver, and myelin-stained preparations. our chief goals were to define the cytoarchitectonic subdivisions and boundaries in nissl preparations and to reconcile these with those observed with the golgi method and in experimental material, to present these results in an atlas of nissl-stained sections, and to compare the chief nuclear groups in the opossum ...19882464620
characterization of serotonin-1b receptors negatively coupled to adenylate cyclase in ok cells, a renal epithelial cell line from the opossum.we have previously reported the presence of a 5-ht1 (serotonin)-like receptor coupled in an inhibitory manner to adenylate cyclase in the opossum kidney cell line, which is derived from the kidney of a north american opossum. pharmacological data from binding and cyclic amp production studies indicate that this receptor does not have characteristics of a 5-ht1a, 5-ht1c or 5-ht1d receptor, but is similar to 5-ht1b receptors found in rodent tissues. many serotonergic drugs, including 5-methoxy-3-( ...19892542534
opossum kidney contains a functional receptor for the escherichia coli heat-stable enterotoxin.the escherichia coli heat-stable enterotoxin (st1 or sta) binds to specific receptors on mammalian intestinal brush border membranes, and stimulates guanylate cyclase in those membranes. we have found a similar signal transduction system in brush border membranes prepared from kidney cortex of the american opossum (didelphis virginiana, and in a cell line (ok cell) derived from that tissue. activation of guanylate cyclase by st1 is therefore not limited to intestinal cells. furthermore, since it ...19892564275
fatal lungworm infection in an opossum.a 3-mo-old male, feral opossum (didelphis virginiana) was presented to the university of tennessee college of veterinary medicine (usa) for evaluation of prolonged dyspnea. the animal died shortly after examination and a necropsy was performed. the cause of death was attributed to a verminous pneumonia, associated with numerous intrabronchial and intrabronchiolar nematodes, subsequently identified as didelphostrongylus hayesi.19892716108
a double-labelling study of reticular collaterals to the spinal cord and cerebellum of the north american opossum.injections of horseradish peroxidase into either the spinal cord or cerebellum label neurons in the gigantocellular and lateral reticular nuclei of the north american opossum. in order to determine if neurons which project to the spinal cord and cerebellum are intermingled in these two nuclei and if single neurons provide collaterals to both areas, we have employed fluorescent markers in double-labelling experiments. our results show that reticular neurons innervating either the spinal cord or c ...19846205332
a study of overlap and collateralization of bulbar reticular and raphe neurons which project to the spinal cord and diencephalon of the north american opossum.labeled neurons were found in most reticular and raphe nuclei of the opossum's medulla after horseradish peroxidase (hrp) injections into either the spinal cord or diencephalon. the labeling produced by spinal injections differed somewhat from that produced by diencephalic ones, but hrp-positive neurons were found in what appeared to be comparable areas. in order to study the intermingling of bulbospinal and bulbodiencephalic neurons more directly, we used fluorescent markers (true blue, nuclear ...19846205718
a pharmacological study of oesophageal muscularis mucosae from the cat, dog and american opossum (didelphis virginiana).strips of muscularis mucosae from the oesophagi of cat, dog and opossum have been studied to determine their responses to drugs to electrical field stimulation. all tissues were contracted by acetylcholine, histamine and, with the exception of strips of muscularis mucosae from the opossum proximal oesophagus, noradrenaline. the effects of acetylcholine and histamine were competitively antagonized by atropine (50 nm) and mepyramine (50 nm) and were abolished by atropine (1 microm) and mepyramine ...19846207883
isolation from opossum serum of a metalloproteinase inhibitor homologous to human alpha 1b-glycoprotein.fractionation of opossum (didelphis virginiana) serum with (nh4)2so4, followed by chromatography on deae-sepharose, phenyl-sepharose, and mono q hr 5/5, has resulted in the isolation in homogeneous condition of a metalloproteinase inhibitor designated oprin (opossum proteinase inhibitor). oprin is a single-chain glycoprotein (26% carbohydrate) with an estimated mr = 52,000, pi = 3.5, and e(1%/1 cm) = 11. oprin inhibited snake venom metalloproteinases, but showed no activity on venom serine prote ...19921731898
description of sarcocystis falcatula stiles, 1893, a parasite of birds and opossums.sarcocystis falcatula stiles, 1893 is re-described. intermediate hosts of the parasite which was earlier described as sarcocystis debonei vogelsang, 1929 are species of passeriform, psittaciform, and columbiform birds. in these birds, muscle zoites are 6.88 x 2.19 (4.8-8.4 x 1.2-3.6) micron and are enclosed in a cyst wall with regular protrusions, 1-5 micron long. the convoluted primary wall has multiple thin areas in the osmiophilic layer. microtubules originate in the ground substance and exte ...19846439855
light- and electron-microscopic demonstration of immunoreactive opsin in the pinealocytes of various antibody to opsin isolated from rod outer segments of the frog retina was applied in light- and electron-microscopic immunocytochemical studies to the pineal organ of various vertebrates (cyprinus carpio, carassius auratus, rana esculenta, emys orbicularis, pseudemys scripta elegans, lacerta agilis and viridis. gallus domesticus, columba livia, melopsittacus undulatus, serinus canaria, taeniopyga punctata, didelphis virginiana, erinaceus roumanicus, myotis myotis, rabbit, rat, cat).19816458362
a cyto-architectonic description of the thalamus of the tammar wallaby, macropus eugenii.very few studies are available on the cyto-architectural features of the thalamus of metatherian mammals. most of these studies describe the thalamus of a polyprotodont metatherian, the north american opossum, didelphis virginiana. studies on diprotodont metatherians are fewer still. there are two descriptions of the thalamus of the australian possum trichosurus vulpecula. the only part of the thalamus that has been described in the wallabies is the lateral geniculate nucleus. hence, there was a ...19892765853
studies on the energy metabolism of opossum didelphis virginiana erythrocytes--iv. red cells have low adenosine deaminase activity and high levels of deoxyadenosine nucleotides.alkaline extracts of adult opossum red cells were used to determine triphosphates of adenosine, deoxyadenosine and guanosine by anion exchange hplc. mean (nm/g hg) atp content of erythrocytes was 3713 and that of datp 1913 (n = 12). sonicates of red cells deaminated adenosine (ado) at a rate of 1.55 nm/mg hg/h and deoxyadenosine (dado) at 1.82 nm/mg hg/h. datp synthesis from provided dado was one order of magnitude greater in opossum than in human erythrocytes at both low and high dado and pi co ...19892784528
bacterial flora of the gastrointestinal tract of opossums.the bacterial flora of the stomach, small intestine, cecum and bile from 20 healthy opossums (didelphis virginiana) captured from the wild was studied. results showed that their gastrointestinal flora was similar to that found in other small mammals but, in addition, opossums are heavily colonized by salmonella spp., which might adversely affect their adequacy as laboratory animals for some experimental protocols.19921557901
life cycle and development of lagochilascaris sprenti (nematoda: ascarididae) from opossums (marsupialia: didelphidae) in louisiana.the life cycle of lagochilascaris sprenti, a species which occurs in the stomach of opossums (didelphis virginiana) in louisiana, was determined. the larva in the egg developed to the infective stage after eggs from the feces of infected animals were in culture about 30 days. when eggs containing infective larvae were fed to mice, the larvae hatched, penetrated the intestinal mucosa, migrated through the liver and lungs, and eventually reached the skeletal muscles where they became encapsulated. ...19836685179
molecular studies of marsupial x chromosomes reveal limited sequence homology of mammalian x-linked explore the extent to which the x chromosome has been conserved during mammalian evolution, we compared six loci that are x-linked in the human genome with the corresponding genes of the north american marsupial, the virginia opossum (didelphis virginiana). our analysis shows that in the opossum genome there are sequences highly homologous to those of human cdnas for housekeeping genes, glucose-6-phosphoribosyltransferase (hprt), phosphoglycerate kinase a (pgk1), and alpha-galactosidase a (gl ...19872822568
the epidemiology of toxoplasmosis on iowa swine farms with an emphasis on the roles of free-living mammals.multiparous sows from 19 central iowa swine farms were tested for antibodies against toxoplasma gondii by the modified direct agglutination test. antibody titers of 1:32 or greater were considered positive. rodents, domestic cats, opossums (didelphis virginiana), raccoons (procyon lotor) and striped skunks (mephitis mephitis) were live-trapped on each farm and similarly tested for antibodies. the overall prevalence of t. gondii antibodies in the species tested was 39/273 (14.3%) swine, 31/74 (41 ...19921496780
studies on the energy metabolism of opossum didelphis virginiana erythrocytes--ii. comparative aspects of 2-deoxy-d-glucose catabolism in opossum and human red cells in vitro.1. g-6-p, f-6-p, f-1, 6-p, dhap and ga-3-p in opossum erythrocytes were found at levels above those reported in human red cells. 2. about 1% of the radioactivity provided as [1-14c] dog to red cells of both species was recovered as 14co2 in 1 hr. 3. unlike [1-14c] dog, radiochromatography of extracts of cells incubated dog revealed two diffusible radiolabelled compounds in the supernatant of cell suspensions. 4. the catabolism of dog was quantitatively and qualitatively similar in opossum and hu ...19882896089
sarcocystis of passerine birds: sexual stages in the opossum (didelphis virginiana).sexual stages of a sarcocystis of passerine birds were demonstrated by feeding muscle cysts from cowbirds (molothrus ater) and grackles (cassidix mexicanus) to opossums (didelphis virginiana). opossums were examined at necropsy at 36 h, 13.5 days, and 29.5 days post-inoculation (pi). large numbers of macro- and microgamonts were present in the small intestine 36 h pi, while only sporocysts and oocysts were present 13 days or more pi. microgamonts in different stages of development were in the in ...19806776294
studies on the energy metabolism of opossum didelphis virginiana erythrocytes--iii. metabolic depletion with 2-deoxyglucose markedly accelerates methemoglobin reduction in opossum but not in human erythrocytes.1. glucose-depleted, nitrite-treated erythrocytes reduce ferriheme in vitro in an environment 100 mm to 2-deoxy-d-glucose at a rate of 2.4 microm/ml cells/hr (opossum) and 0.37 microm/ml cells/hr (human). 2. during the process of methemoglobin reduction the breakdown of adenine ribonucleotides is more rapid in opossum (0.9 microm/g hg/hr) than in human (0.36 microm/g hg/hr) erythrocytes. 3. radiolabelled ribose from [u-14c] atp is catabolized exclusively to [14c] lactate in opossum, and to [14c] ...19882896090
catecholaminergic innervation of the spinal cord in the north american opossum, didelphis virginiana.axons presumed to contain catecholamines were visualized in the spinal cord of the spinal cord of the north american opossum using antibodies to tyrosine hydroxylase (th) by an indirect antibody peroxidase-antiperoxidase (pap) technique. axons showing th-like immunoreactivity (th-ir) coursed primarily in the dorsal part of the lateral funiculus, although they were also present more ventrally. an occasional th-ir axon was seen in the dorsal funiculus. within the gray matter, th-ir axons were dist ...19882906810
sarcocystis spp. in white-tailed deer. i. definitive and intermediate host spectrum with a description of sarcocystis odocoileocanis n. sp.sporocysts containing four sporozoites and measuring (avg.) 15.2 micrometers x 10.7 micrometers (n = 195) were shed in the feces of dogs (canis familiaris) 8 to 16 days (avg. 11.6 days) after the first feeding of venison infected with sarcocystis sp. sporocysts containing four sporozoites and measuring (avg.) 11.5 micrometers x 8.1 micrometers (n = 35) were shed by a cat (felis catus) 14 days after ingesting sarcocystis-infected venison. statistical (pooled t-test) comparison of the mean measure ...19816802990
the intermediate host spectrum in a sarcocystis species of birds.the life cycle of an avian sarcocystis has been completed in the laboratory, originating with naturally infected icterids and passing alternately between opossums (didelphis virginiana) and experimentally infected birds. to determine the intermediate host range, six avian species, including canaries (serinus canarius), zebra finches (poephila guttata), budgerigars (melopsittacus undulatus), pigeons (columba livia), chickens (gallus gallus), and guinea fowl (numida meleagris), were inoculated ora ...19826811715
receptive field properties and latencies of cells in the lateral geniculate nucleus of the north american opossum (didelphis virginiana).relay cells in the lateral geniculate nucleus (lgn) of the north american opossum were classified as types 1, 2, and 3 on the basis of their receptive field properties and afferent latencies to optic nerve (on) and optic chiasm (ox) stimulation and antidromic latencies to stimulation of cortex. type 1 and type 3 cells gave transient responses and type 2 cells gave sustained responses to appropriate standing contrast in the receptive field center. the differences in response pattern were quantifi ...19863097274
pathogenesis of sarcocystis falcatula in the budgerigar. i. early pulmonary schizogony.sarcocystis falcatula is a protozoan parasite which obligatorily alternates its definitive host, the opossum (didelphis virginiana), and a uniquely wide range of avian intermediate hosts. the disease produced by this coccidian parasite in intermediate hosts was studied in the budgerigar bird (melopsittacus undulatus). the ultrastructure of pulmonary sporozoites, meronts and merozoites of this sarcocystis species is described. early schizogony occurs progressively in pulmonary capillary and in ve ...19873099083
pathogenesis of sarcocystis falcatula in the budgerigar. ii. pulmonary pathology.sarcocystis falcatula is a protozoan parasite which obligatorily alternates its definitive host, the opossum (didelphis virginiana), and a uniquely wide range of avian intermediate hosts. the disease produced by this coccidian parasite in intermediate hosts was studied in the budgerigar bird (melopsittacus undulatus). early schizogony occurs in pulmonary endothelial cells, resulting in endothelial cell hypertrophy, capillary obstruction preceding endothelial lysis, acute endophlebitis, and chron ...19873099084
opportunistic fungi in detroit's rats and opossum.four norway rats (rattus norvegicus) and one opossum (didelphis virginiana) were surveyed for the presence of fungi. eighteen different fungi were isolated from rat samples and six from the opossum, including trichophyton mentagrophytes. hair and skin scrapings from laboratory raised norway rats, bedding and air from the room yielded only penicillium sp.19806991950
structure, processing and evolution of the neurohypophysial hormone-neurophysin precursors.neurohypophysial hormones and neurophysins are derived from common precursors processed during the axonal transport from the hypothalamus to the neurohypophysis. two neurohormones, an oxytocin-like and a vasopressin-like, on one hand, two neurophysins, termed vldv-and msel-neurophysins according to residues in positions 2, 3, 6 and 7, on the other, are usually found in vertebrate species. in contrast to placental mammals that have oxytocin and arginine vasopressin, marsupials have undergone a pe ...19883147712
husbandry of a small breeding colony of opossums (didelphis virginiana).a small breeding colony of opossums was established in a semi-enclosed structure. minor modifications of pre-existing pens permitted efficient and productive management of the opossums. dry dog food was provided, and large amounts of shredded paper was used for nesting material. vaginal smears were taken from opossums that were restrained only by their tail, a procedure that allowed one person to obtain and interpret vaginal smears from 20 females in less than 2 hours per day. pregnancy resulted ...19827144133
natural la crosse virus infection in the red fox (vulpes fulva), gray fox (urocyon cinereoargenteus), raccoon (procyon lotor), and opossum (didelphis virginiana).natural infection of sentinel red foxes (vulpes fulva) and free-ranging red foxes, gray foxes (urocyon cinereoargenteus) and raccoons (procyon lotor) with la crosse (lac) virus was demonstrated. one isolate of lac virus was obtained from a sentinel red fox in an enzootic area. the viremia titer of the lac virus-infected red fox was above the threshold of infection for aedes triseriatus mosquitoes. antibody responses were measured by the microneutralization test employing four california group vi ...19817258486
trichinella spiralis in an agricultural ecosystem. iii. epidemiological investigations of trichinella spiralis in resident wild and feral part of a larger epidemiological study examining the transmission of trichinella spiralis in an agricultural ecosystem, resident wild and feral animals were trapped to determine the extent of their involvement in the natural, on-farm cycling of the parasite among swine. during a 21-mo-study, seven of 15 skunks (mephitis mephitis), one of three opossums (didelphis virginiana), two of two feral domestic cats and a raccoon (procyon lotor) were found to be infected, while five shrews (blarina bre ...19883193554
valvular endocarditis associated with experimental erysipelothrix rhusiopathiae infection in the opossum (didelphis virginiana).intravenous inoculation of a wild type isolate of erysipelothrix rhusiopathiae in opossums resulted in valvular endocarditis in all infected animals. opossums were inoculated once a week for 3 weeks. lesions became visible with cardiac ultrasound by week four post-inoculation. opossums remained clinically normal throughout the experiment, and preinfection body weight was maintained. other lesions of chronic erysipelas including skin necrosis and arthritis were not found in infected opossums.19883374091
characterization of erysipelothrix rhusiopathiae isolated from an opossum (didelphis virginiana) with septicemia.erysipelothrix rhusiopathiae was isolated from a wild-caught opossum (didelphis virginiana). the opossum was quarantined in isolation and removed from contact with other animals. after a 2-mo period it was found dead in its cage, and presented for postmortem examination. pure cultures of erysipelothrix rhusiopathiae (slu isolate) were recovered from heart blood, liver, spleen and lungs. to compare pathogenicity, an experimental infection was attempted in cf1 mice with a single dose of 1.5 x 10(7 ...19883411715
experimental la crosse virus infection of red fox (vulpes fulva), raccoon (procyon lotor), opossum (didelphis virginiana), and woodchuck (marmota monax).susceptibility to infection, resulting viremia and antibody responses, and potential to provide infectious blood meals for aedes triseriatus were determined and compared for the red fox (vulpes fulva), raccoon (procyon lotor), and opossum (didelphis virginiana) exposed to la crosse (lac) virus transmitted by mosquitoes, ae. triseriatus. woodchucks (marmota monax) were infected with lac virus by needle and syringe. all 5 red foxes became viremic following the bite of a single lac virus-infected f ...19854003669
responses of opossum and rat hippocampal ca1 cells to paired stimulus volleys.short-term synaptic plasticity was studied in the in vitro hippocampus of the north american opossum (didelphis virginiana) and rat (rattus norvegicus). conditioning and test stimulus pulses were delivered to fibers in stratum radiatum, and intracellular and extracellular recordings were obtained from area ca1 pyramidal cells. in rat, the amplitude of the population spike in response to the second (test) of two stimulus impulses is suppressed at short inter-pulse-intervals (ipi's). in opossum, t ...19854052826
the distribution of glutamic acid decarboxylase immunoreactivity in the diencephalon of the opossum and rabbit.we have examined the distribution of neurons and terminals immunoreactive for glutamic acid decarboxylase (gad) in the thalamus and adjacent structures of the opossum (didelphis virginiana) and the rabbit and have compared this distribution with the distributions we described previously for the cat and bushbaby (galago senegalensis). the significance of these experiments depends, first, on the fact that gad is the synthetic enzyme for gaba, and therefore that gad immunoreactivity is a marker for ...19846090511
ectoparasites of opossums and raccoons in southeastern georgia.twelve species of ectoparasites (four fleas, three ticks, three chiggers, one macronyssid mite, and one atopomelid mite) were recovered from 42 opossums, didelphis virginiana kerr, live-trapped from september 1992 through april 1994 in southeastern georgia. the fleas, ctenocephalides felis (bouché) (prevalence = 19%) and polygenis gwyni (c. fox) (36%); the ticks, dermacentor variabilis (say) (40%) and ixodes scapularis say (19%); and the macronyssid mite, ornithonyssus wernecki (fonseca) (21%), ...19947815408
substance p immunoreactivity in the median eminence of the north american opossum and domestic fowl. 19806154507
immunohistochemical localization of substance-p, somatostatin, and methionine-enkephalin in the spinal cord and dorsal root ganglia of the north american opossum, didelphis virginiana.the occurrence and distribution of substance-p (sp), somatostatin (som), and enkephalin (enk) were studied in the north american opossum, a generalized marsupial. substance-p immunoreactivity was present in the tract of lissauer as well as within lamina i, the outer part of lamina ii, the lateral portion of laminae iii through vii, and lamina x at all spinal levels. although present, it was very spare in the ventral horn. substance-p was also localized within autonomic areas of the thoracolumbar ...19816165743
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