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At least 487 records · Page 27Linked to original sources
PubMed1990

Eradication of Helicobacter mustelae from the ferret stomach: an animal model of Helicobacter (Campylobacter) pylori chemotherapy.

Colonization of the ferret stomach by Helicobacter mustelae has been suggested as a possible animal model for Helicobacter pylori-associated gastroduodenal disease of humans. Our study was designed to determine whether antimicrobial chemotherapy could eradicate H. mustelae from ferrets. Triple antimicrobial therapy combining amoxicillin, metronidazole, and bismuth subsalicylate was successful in eradicating the organism from 5 of 7 (71%) adult ferrets. Despite apparent in vitro susceptibility, neither chloramphenicol monotherapy nor a polytherapeutic regimen combining tetracycline, metronidazole, and bismuth subsalicylate proved effective in the eradication of H. mustelae. Several strains isolated after unsuccessful polytherapy showed markedly increased resistance to metronidazole. These preliminary findings are similar to results of H. pylori treatment trials with humans and suggest that the ferret may be a useful model for evaluating and comparing potential antimicrobial modalities for the eradication of H. pylori.

Animals↗
PubMed1978

Local and systemic immunity to influenza infections in ferrets.

To establish whether immunity to influenza infection in the ferret is local or systemic, two sites of challenge were utilized: the nose and the anatomically isolated tracheal pouch. Infection of either site did not spread to the other site, and challenge of either site resulted in seroconversion by 13 days. Simultaneous challenge of both sites 21 days after the primary infection revealed that prior infection of the pouch prevented subsequent reinfection of the pouch, but not infection of the nose. Thus, systemic immunity did not prevent the initiation of nasal influenza infection in the ferret. However, the duration of virus shedding from the nose was reduced to half of that seen when ferrets were infected for the first time, showing that the prior pouch infection did lead to a more rapid recovery from the subsequent nasal infection. Passively administered anti-influenza antibody did not prevent or modify the nasal infection, but it did prevent the pouch infection. This is consistent with the observation that an initial infection of the nose prevented pouch infection upon challenge 21 days later. The prior nasal infection also prevented the subsequent nasal infection. These data suggest that immunity to acquisition of influenza infection in the ferret is a local phenomenon, whereas recovery from active infection is influenced by systemic immune mechanisms.

Animals↗
PubMed2001

Antigastric autoantibodies in ferrets naturally infected with Helicobacter mustelae.

Infection with Helicobacter pylori has been associated with induction of autoantibodies that cross-react with the gastric mucosa. There have been discordant reports as to whether or not these autoantibodies arise due to molecular mimicry between H. pylori and host cell antigens on parietal cells. In this study, we investigated whether molecular mimicry by H. mustelae causes autoantibodies in infected ferrets. Serum from H. mustelae-infected ferrets reacted with parietal cells in the ferret gastric mucosa but not with duodenal or colonic mucosa. These sera did not react with the blood group A epitope on erythrocytes or H. mustelae lipopolysaccharide, and absorption with H. mustelae whole cells or red blood cells did not remove autoantibodies. In conclusion, ferrets naturally infected with H. mustelae generate antibodies that react with parietal cells, but these autoantibodies are not due to molecular mimicry.

ABO Blood-Group System↗
PubMed1979

Immunological studies of subacute measles encephalitis in ferrets: similarities to human subacute sclerosing panencephalitis.

Ferrets inoculated with subacute sclerosing panencephalitis virus strains D.R. and Biken developed a subacute encephalitis. Brain extracts, at neutral pH, from these ferrets showed high measles antibody titers, increased concentrations of immunoglobulin G (IgG), and higher IgG/albumin ratios than those of controls. Although the brain extracts of subacute encephalitic animals showed significant synthesis of measles-specific IgG (20 to 60% of the total IgG) within the central nervous system, the electrophoretic patterns of these extracts did not show oligoclonal bands in the gamma-globulin region. Brain residues from most ferrets with subacute encephalitis, when eluted at low pH, demonstrated the presence of bound measles-specific antibodies. Excluding the electrophoresis data, other results are identical to those seen in human subacute sclerosing panencephalitis, indicating that the subacute encephalitis in ferrets may serve as a model for human subacute sclerosing panencephalitis.

Animals↗
PubMed1991

Mn and Cd transport by the Na-Ca exchanger of ferret red blood cells.

Ca influx via the Na-Ca exchanger into ferret red blood cells is easily measured from a Na-free solution; the intracellular Na concentration is normally approximately 150 mM in ferret red blood cells. We have found that Mn and Cd competitively inhibit Ca influx. Mn influx and Cd influx were a saturable function of the divalent cation concentration, consistent with a carrier mechanism. Indeed, the Km (approximately 10 microM) and the Vmax (usually 1-3 mmol.l packed cells-1.h-1) were similar for Ca, Cd, and Mn. Extracellular Na inhibited divalent cation influx, and intracellular Na stimulated influx. These results are consistent with Na-Cd and Na-Mn influx pathways in ferret red blood cells. Ca (1 mM) almost completely inhibited Mn influx and Cd influx, whereas 1 mM Mg inhibited 5-15%. These results strongly support the notion that Mn and Cd are alternative substrates for Ca on the ferret red cell Na-Ca exchanger. The similarity in the behavior of all three divalent cation places important constraints on kinetic and structural models of the exchanger.

Animals↗
PubMed2002

Comparative analysis of aortic impedance and wave reflection in ferrets and dogs.

Our modified version of the T-tube arterial model (consisting of two parallel, loss-free transmission paths terminating in lumped loads of complex and frequency-dependent nature) was applied to experimental measurements of ascending aortic pressure and of ascending and descending aortic flows taken from dogs and ferrets. Our aim was to provide quantitative evaluation of the aortic pressure and flow pulse wave components as they relate to the distribution of arterial properties and relate to wave travel and reflection in mammalians of consistently different size and shape. Estimated effective lengths (distances to effective reflection sites) of the head-end (d(h)) and body-end (d(b)) transmission paths were approximately 12 and 30 cm, respectively, in the dog and 6.5 and 13 cm, respectively, in the ferret. These lengths and distributions of estimated arterial properties were consistent with the difference in the body size and with the more central location of the heart in the ferret's body than it is in the dog's body. In both animal species the ascending aortic pressure and flow waves could be interpreted in terms of forward and reflected components arising from the two distinct effective reflection sites, although the higher d(h)/d(b) ratio in the ferret determined the presence of one broad, indistinct minimum in the modulus of ascending aortic impedance in the frequency range from 0 to 10 Hz, rather than two distinct minima as observed in the dog.

Animals↗
PubMed1981

Pulmonary mechanisms of the normal ferret.

Pulmonary mechanics were measured in normal anesthetized male Fitch ferrets (200-360 g). In eight transorally intubated ferrets, pressure-volume (PV) curves for the lung and chest wall were obtained with an esophageal balloon and body plethysmograph. The lung volumes and capacities expressed as a percentage of the total lung capacity (mean, 49.8 ml) were: vital capacity, 84.7%; inspiratory capacity, 63.7%; inspiratory reserve volume, 58.2%; functional residual capacity, 33.8%; expiratory reserve volume, 16.8%; residual volume, 15.3%; and tidal volume, 8.0%. The compliance of the lung (2.93 ml . cmH2O-1), chest wall (22.42 ml . cmH2O-1) and respiratory system (2.55 ml . cmH2O-1) were determined from the PV curves. The dynamic compliance (1.6 ml . cmH2O-1), pulmonary resistance (0.024 cmH2O . ml-1 . s), frequency of breathing (43.5 breaths . min-1), and minute ventilation (195 ml . min-1) were measured during spontaneous breathing. In a second group of 10 ferrets the total airway resistance (0.116 cmH2O . ml-1 . s) and specific conductance (0.915 ml . s-1 . cmH2O . ml-1) were measured during spontaneous nasal breathing. In general the pulmonary mechanics of the ferret were similar to those of the rabbit and dog, when the data were normalized for lung volume.

Airway Resistance↗
PubMed1989

Electromechanical coupling of ferret airway smooth muscle in response to leukotriene C4.

We investigated the possible electrophysiological basis for the slow, prolonged force generation by airway smooth muscle (ASM) produced by leukotriene C4 (LTC4). Preparations of ASM were made from ferret trachea and placed in tissue microchambers for study. Some of these preparations were arranged so that force transducers and intracellular microelectrodes (with tip resistances of 30-80 M omega) could be used to measure isometric force and cell membrane potential (Em) simultaneously from ASM cells stimulated by LTC4. We found that ferret tracheal muscle was relatively sensitive to LTC4 and that this sensitivity was not significantly affected by atropine (1 microM), phentolamine (1 microM), propranolol (3 microM), and pyrilamine (1 microM). In a 1 nM solution of LTC4, Em was -54.0 +/- 1.2 mV from 18 impalements (n) from 6 animals (N) compared with a base-line value of -61.6 +/- 0.8 mV (n/N = 29/8, P less than 0.0005). This change did not lead to force generation, however. Higher concentrations of LTC4 led to progressive decreases in Em to which force generation was closely coupled. Concentrations greater than or equal to 70 nM led to phasic oscillations in Em of 0.6-0.8 Hz and 1.7 mV in amplitude, which were abolished by 10 microM verapamil, although the base-line Em was unaffected by this concentration. Although 300 nM LTE4 by itself caused only a small depolarization of ferret trachealis, it substantially antagonized the electromechanical responsiveness of this smooth muscle to LTC4. We conclude that ferret ASM is relatively sensitive to LTC4 and that there is an electrical basis for the slow, prolonged force generation caused by this mediator.

Animals↗
PubMed1999

Enhanced NR2A subunit expression and decreased NMDA receptor decay time at the onset of ocular dominance plasticity in the ferret.

Enhanced NR2A subunit expression and decreased NMDA receptor decay time at the onset of ocular dominance plasticity in the ferret. The NMDA subtype of glutamate receptor is known to exhibit marked changes in subunit composition and functional properties during neural development. The prevailing idea is that NMDA receptor-mediated synaptic responses decrease in duration after the peak of cortical plasticity in rodents. Accordingly, it is believed that shortening of the NMDA receptor-mediated current underlies the developmental reduction of ocular dominance plasticity. However, some previous evidence actually suggests that the duration of NMDA receptor currents decreases before the peak of plasticity. In the present study, we have examined the time course of NMDA receptor changes and how they correlate with the critical period of ocular dominance plasticity in the visual cortex of a highly binocular animal, the ferret. The expression of NMDA receptor subunits NR1, NR2A, and NR2B was examined in animals ranging in age from postnatal day 16 to adult using Western blotting. Functional properties of NMDA receptors in layer IV cortical neurons were studied using whole cell patch-clamp techniques in an in vitro slice preparation of ferret primary visual cortex. We observed a remarkable increase in NR1 and NR2A, but not NR2B, expression after eye opening. The NMDA receptor-mediated synaptic currents showed an abrupt decrease in decay time concurrent with the increase in NR2A subunit expression. Importantly, these changes occurred in parallel with increased ocular dominance plasticity reported in the ferret. In conclusion, molecular changes leading to decreased duration of the NMDA receptor excitatory postsynaptic current may be a requirement for the onset, rather than the end, of the critical period of ocular dominance plasticity.

Aging↗
PubMed1983

Normal differentiation of masculine sexual behavior in male ferrets despite neonatal inhibition of brain aromatase or 5-alpha-reductase activity.

Male ferrets born in the laboratory received subcutaneous Silastic capsules containing either the aromatase inhibitor, androst-1,4,6-triene-3, 17-dione (ATD), the 5 alpha-reductase inhibitor, testosterone-17 beta-carboxylic acid (17 beta C), or no hormone, for 15 days beginning on the day of birth; an additional group of females received empty Silastic capsules. All ferrets were gonadectomized when 11 weeks of age and were subsequently tested for masculine sexual behavior after a latin-square sequence of treatments with subcutaneous Silastic capsules containing testosterone (T), estradiol (E), or dihydrotestosterone (DHT). After T, control males displayed significantly more neck gripping, mounting and pelvic thrusting than control females, and males treated neonatally with ATD or 17 beta C were no less responsive than control males. After DHT, little masculine sexual behavior was shown by any group. After E, the duration of mounting was significantly longer in control and ATD males than in control females or 17 beta C males. Subsequently, however, there were no differences between control and 17 beta C males on any parameter of masculine sexual performance, when they were retested sequentially after subcutaneous implantation of E followed by E + DHT. Additional groups of newborn male and female ferrets received subcutaneous capsules containing either ATD, 17 beta C, or no hormone and were killed on postnatal day 7. Administration of ATD, but not 17 beta C, strongly inhibited aromatase activity in the hypothalamus + preoptic area. In all groups, the formation of significantly inhibited cortical 5 alpha-reductase activity. Plasma concentrations of T were equivalent on postnatal day 7 in males given each of the neonatal treatments. These results suggest that behavioral masculinization in the male ferret results primarily from the neonatal action in brain of T itself, and not from its estrogenic or 5 alpha-reduced androgenic metabolites.

5-alpha Reductase Inhibitors↗
PubMed1989

The ferret as an animal model in cerebrovascular research.

Clinical and pathologic observations have suggested analogies between the developing nervous system of ferrets (Mustela putorius furo) and those of more traditional animal models employed in stroke research. Experimental work has demonstrated advantages of the ferret as a model of visual development. We performed in vivo cerebral angiography and postmortem neurovascular dissection of latex-injected specimens of adult ferrets. The great vessels include a cervical arterial trunk that gives rise to both carotid arteries. The anatomy of the cranial arteries is similar to that of rabbits. No carotid rete mirabile is present. There are no intracranial anastomoses between the external and internal carotid systems. We present in vivo cerebral angiograms with pathologic correlation that demonstrate that ferrets may provide the same anatomic advantages as a rabbit model for the experimental study of cerebrovascular disease, with the additional advantage of a long extracranial cervical segment of the carotid artery, affording easier access to the intracranial vasculature.

Animals↗
PubMed1998

Human respiratory syncytial virus produces prolonged alterations of neural control in airways of developing ferrets.

A dysfunction of pathways that normally cause contraction or relaxation of airways has been proposed to explain heightened levels of responsiveness produced by various insults to the airway. For example, we previously reported (4) that infection of cotton rats with the human respiratory syncytial virus (HRSV) leads to a significant decrease in an airway's nonadrenergic noncholinergic inhibitory (NANCi) response shortly after the infection. In the present study we addressed the more chronic effects of HRSV infection on airway function in young ferrets during a period of rapid somatic growth. Animals 1 wk old received HRSV or uninfected cell culture medium intranasally. In vitro studies of airway function were performed on tracheal smooth muscle (TSM) segments at 4, 8, and 24 wk of age. To evaluate neurally mediated contractile responses, frequency-response curves to electrical field stimulation (EFS) were performed with results expressed in terms of the frequency causing 50% of the maximal contractile response (ES50). In addition, contractile responses of TSM to methacholine (MCh) were also assessed with results expressed as the concentration needed to produce 50% of the maximal contractile response (EC50). To gauge NANCi responses, TSM was contracted with neurokinin A in the presence of atropine, propranolol, and indomethacin. Relaxant responses to EFS were assessed at frequencies from 5 to 30 Hz, with results expressed as mean percent relaxation. We found increased contractile responses to EFS in infected animals compared with that in the control group in both 4- and 8-wk old animals (p = 0.001 and p = 0.008, respectively). This difference had resolved by 24 wk of age. There was no difference in TSM responses to MCh between the groups at any age. Although there were no NANCi responses in 4-wk-old ferrets from either group, NANCi responses were significantly decreased in 8-wk-old ferrets previously infected with HRSV in the first week of life (p = 0.0001). A significant difference persisted (p = 0.008), albeit to a lesser degree, at 24 wk of age. These findings demonstrate that HRSV produces prolonged alterations of TSM function in ferret airways in vitro.

Animals↗
PubMed1991

Attachment of influenza A virus to ferret tracheal epithelium at different maturational stages.

Influenza virus attaches primarily to ciliated cells in mature airways epithelium. This process is mediated by a viral envelope glycoprotein (hemagglutinin) that binds to sialic acid-containing receptors in the apical membrane of host cells. The purpose of this study was to determine the cellular distribution of these receptors as a function of tracheal epithelial maturation in the ferret, which is susceptible to influenza virus infection at all ages and undergoes postnatal ciliation. To assay for virus attachment, tracheal strips from ferrets at ages 0, 7, 14, and 28 d were incubated at 4 degrees C for 1 h with a concentrated suspension of influenza A virus. Transmission electron microscopy demonstrated virus attachment to the apical surface of 77 to 87% of ciliated cells, but only to 1 to 9% of nonciliated surface epithelial cells at all ages, including the newborn, which has few ciliated cells (less than 10% of total cells). Virions also attached to most of the preciliated cells identified. Pretreatment of tracheal strips with neuraminidase virtually eliminated viral attachment. These findings demonstrate preferential influenza virus binding to sialylated receptors on ciliated cells and their immediate precursors. The sparsity of ciliated cells with no evidence for increased influenza virus binding per cell in newborn ferret tracheas suggests that the previously demonstrated high risk of death from influenza infection in newborn ferrets is due to factors other than increased susceptibility to virus attachment. Influenza virus receptors appear to be selective membrane markers for ciliated cells and may be particularly useful for the identification of preciliated cells.

Animals↗
PubMed1990

Measurement of dietary and dentifrice effects upon calculus accumulation rates in the domestic ferret.

Most animal models for the study of calculus accumulation and control currently use rodents or dogs. In an effort to overcome limitations inherent in the use of these species, we investigated calculus formation in domestic ferrets, a species used by King et al. in the 1940's and 1950's. Ferrets are much smaller than dogs, and, unlike rodents, can be scored while alive. In this study, we examined the kinetics of calculus formation in female ferrets fed with moist canned cat food--either plain or supplemented with sucrose--and two combinations of mineral salts. An additional group given supplemented cat food was treated twice daily with regular Crest toothpaste. Animals were sedated with a 1:1 mixture of ketamine and xylazine solutions and given a mechanical prophylaxis prior to the trial period, then scored for area and extent of calculus accumulation at two, four, six, and eight weeks thereafter. The data showed that the mineral-supplemented groups accumulated calculus at a significantly faster rate than the unsupplemented or dentifrice-treated groups, but the differences were no longer significant at eight weeks. This demonstrated that the ferret is a suitable model for the study of calculus, that dietary mineral content influenced calculogenesis, and that the application of regular dentifrice initially slowed, but did not prevent, calculus accumulation.

Analysis of Variance↗
PubMed2003

Progress toward generating a ferret model of cystic fibrosis by somatic cell nuclear transfer.

Mammalian cloning by nuclear transfer from somatic cells has created new opportunities to generate animal models of genetic diseases in species other than mice. Although genetic mouse models play a critical role in basic and applied research for numerous diseases, often mouse models do not adequately reproduce the human disease phenotype. Cystic fibrosis (CF) is one such disease. Targeted ablation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in mice does not adequately replicate spontaneous bacterial infections observed in the human CF lung. Hence, several laboratories are pursuing alternative animal models of CF in larger species such as the pig, sheep, rabbits, and ferrets. Our laboratory has focused on developing the ferret as a CF animal model. Over the past few years, we have investigated several experimental parameters required for gene targeting and nuclear transfer (NT) cloning in the ferret using somatic cells. In this review, we will discuss our progress and the hurdles to NT cloning and gene-targeting that accompany efforts to generate animal models of genetic diseases in species such as the ferret.

Animals↗
PubMed1984

Effect of neonatal gonadectomy and administration of testosterone on coital masculinization in the ferret.

Male ferrets castrated on postnatal day 5 displayed significantly lower levels of neck gripping, mounting, and pelvic thrusting behavior than groups of males castrated on postnatal days 20 or 35 when tested in adulthood after treatment with testosterone (T). Administering a high dosage of T via sc Silastic capsules to ovariectomized female ferrets over postnatal days 5-20 caused a significant enhancement of all three parameters of masculine coital behavior and ossification of clitorides, in comparison with control females that received no exogenous hormone neonatally. A lower dosage of T given to other ovariectomized females over the same neonatal period caused only slight coital masculinization even though the plasma concentrations of T achieved in females with this particular implant were somewhat higher than the levels normally present in gonadally intact male ferrets at any time between postnatal days 5 and 40. Administration of high and low dosages of T to ovariectomized females over days 20-35 failed to cause any coital or genital masculinization. The results suggest that T acts in the male ferret brain between postnatal days 5 and 20 to cause coital masculinization. The sensitivity of the male brain to T during this period may, however, normally be enhanced by the action of T or some other hormone before day 5.

Animals↗
PubMed1997

Clonal dispersion and evidence for asymmetric cell division in ferret cortex.

Cell lineage analysis with retroviral libraries suggests that clonal progeny disperse widely in rodent cortex. To determine whether widespread dispersion is a general mammalian plan and to investigate phylogenetic differences in cortical development, we analyzed cell lineage in the ferret, a carnivore and near relative of the cat. The ferret possesses a highly developed, folded cerebral cortex, characteristic of higher mammalian species. Progenitor cells of the ferret cerebral cortex were tagged with an amphotropic retroviral library encoding alkaline phosphatase, and sibling relationships were determined using the polymerase chain reaction. Neuronal clones were single neurons (52%) or large clones (48%; average, 7 neurons) containing neurons and glia in widespread cortical locations. Neuronal clones in the ferret labeled at middle to late neurogenesis (embryonic day 33-35) contained large numbers of neurons and showed little tendency to cluster. The large proportion of single neuron clones, contrasted with the large size of multicell clones, suggests that some progenitors divide asymmetrically, producing a postmitotic neuron and regenerating a multipotential cell.

Alkaline Phosphatase↗
PubMed1991

The isolated, buffer-perfused ferret heart: a new model for the study of cardiac physiology and metabolism.

The isolated, buffer-perfused ferret heart is a new model for the study of cardiac physiology and metabolism. Compared to the more commonly used isolated heart preparation, the rat heart, the ferret has a lower rate-pressure product due to lower heart rate, a remarkably low coronary flow and almost complete oxygen extraction. The ferret heart remains in stable haemodynamic and metabolic conditions for a longer period of time than the rat heart. ATP contents of the two species are similar, but creatine phosphate content is higher in the ferret while NAD content is much lower.

Adenosine Triphosphate↗