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At least 901 records · Page 50Linked to original sources
PubMed1995

Vitamin E enhances the lymphatic transport of beta-carotene and its conversion to vitamin A in the ferret.

BACKGROUND/AIMS: beta-Carotene and alpha-tocopherol may have either antagonistic or synergistic effects on each other's absorption and metabolism. The effects of both physiological and pharmacological concentrations of alpha-tocopherol on the absorption and metabolism of beta-carotene in ferret intestine were determined. METHODS: A high concentration of beta-carotene was perfused through the upper portion of the small intestine of ferrets in vivo with varying levels of alpha-tocopherol. The effluent of a mesenteric lymph duct cannulation, the intestinal mucosal scraping, and portal vein blood were sampled and analyzed by high-performance liquid chromatography. RESULTS: The lymphatic transport of beta-carotene was enhanced 4-fold by alpha-tocopherol at a physiological dose and 12-21-fold at a pharmacological dose. The lymphatic transport of alpha-tocopherol was linearly (r = 0.8; P < 0.05) related to the luminal alpha-tocopherol concentration even in the presence of a high concentration of beta-carotene. Furthermore, alpha-tocopherol increased the conversion of beta-carotene into retinol in the intestine in a dose-dependent manner. CONCLUSIONS: alpha-Tocopherol has a positive effect on the intestinal absorption of intact beta-carotene and may modulate the metabolic conversion of beta-carotene into retinoids.

Absorption↗
PubMed1987

Cystic mucinous hyperplasia in the gallbladder of a ferret.

An 8-year-old male ferret had icterus, hepatomegaly and an enlarged gallbladder. Microscopically, the gallbladder had numerous mucinous cysts and papillary hyperplasia of the mucosa, consistent with a diagnosis of cystic mucinous hyperplasia. No previous published reports of this condition in ferrets were found.

Animals↗
PubMed1988

Chordoma in two ferrets.

Chordomas, characterized by lobules of vacuolated cells lying in a mucinous matrix, are described in 2 ferrets. This is the first report of this rare tumour of notochordal remnant origin in the ferret.

Animals↗
PubMed1988

Desheathing the nodose ganglion is not a reliable method of de-efferentation in the ferret.

The present study reports the results of physiological and anatomical experiments in which the purpose was to determine whether desheathing the nodose ganglion is a reliable method of vagal de-efferentation in the ferret. In physiological studies, the effects of electrically stimulating the treated and untreated vagal nerves on cardiovascular and intestinal responses were examined and compared with previously obtained data after left supranodose vagotomy. The anatomical studies illustrated the effects of desheathing the left nodose ganglion on the transport of horseradish peroxidase (HRP) within a thoracic vagal communicating branch. These data were compared to data from control animals and animals that had undergone left supranodose vagotomy. The results demonstrated that severing the fascicles overlying the left nodose ganglion and allowing the nerve fibers to degenerate, caused no reduction in labeled efferent cell bodies in the left dorsal motor nucleus of the vagus as compared to controls. However, after left supranodose vagotomy there were no efferent cell bodies labeled in the left dorsal motor nucleus of the vagus. Following degeneration of the fascicles, electrical stimulation of the peripheral cut end of this nerve did not abolish the efferent responses in 7 out of 9 animals studied, whereas supranodose vagotomy abolished the responses in all animals. These findings demonstrate that desheathing the nodose ganglion and thereby removing the nerve bundles overlying the nodose ganglion is not a guaranteed method of destroying the efferent fibers in the vagus nerve of the ferret. Supranodose vagotomy, therefore, is a more reliable method of de-efferentation in this species.

Animals↗
PubMed1992

The neuropharmacology of loperamide-induced emesis in the ferret: the role of the area postrema, vagus, opiate and 5-HT3 receptors.

Loperamide, an opiate receptor agonist, commonly used in the treatment of diarrhoea, reliably induced emesis in the ferret, when given subcutaneously. The response latency was short (less than 10 min) and the emesis lasted for approx 70 min. The dose-response curve for the emetic response was "bell-shaped" and all animals responded at 0.5 mg/kg but none at 5 mg/kg (s.c.). The response was unaffected by dopamine D2 receptor antagonism (domperidone 1.0 mg/kg, s.c.) or 5-HT3 receptor antagonism (granisetron or ondansetron 1.0 mg/kg, s.c.). The onset of the response was delayed for about 60 min by naloxone or naloxone methiodide (1.0 mg/kg, s.c.) and abolished by naloxanazine (1.0 mg/kg, s.c.), reported to be relatively selective for mu receptors. The results implicate mu receptors (possibly mu 1) in the induction of emesis by loperamide and provide some support for activation of opiate receptors also having anti-emetic effects, as suggested in previous studies. The emetic response to loperamide was unaffected by abdominal vagotomy but was abolished by ablation of the area postrema, indicating that loperamide-induced emesis may be used as a test for ablation of the area postrema in studies of the emetic mechanism in the ferret.

Animals↗
PubMed1987

Reproductive state and motor activity in female ferrets.

The pattern of motor activity in female ferrets (Mustela putorius furo) housed in cages mounted upon rocker platforms was followed under conditions of short-(8 hr) and long-(16 hr) day illumination. A distinct diurnal rhythm was evident that remained unchanged after lesioning of the anterior hypothalamus. The level of activity did not differ between animals kept under short days and long days, between anoestrous and oestrous females, or during the development or waning of oestrus. Ovariectomy did not affect the pattern of activity. These findings are at variance with those of a previous study where wheel-running activity was followed and oestrous females found to be more active than anoestrous ferrets.

Anestrus↗
PubMed1988

Evidence implicating aromatization of testosterone in the regulation of male ferret sexual behavior.

We compared the effects of the aromatase inhibitor, 1,4,6-androstatriene-3,17-dione (ATD) and castration on the expression of mating behavior in adult male ferrets which were in breeding condition. Males implanted SC with Silastic capsules containing ATD displayed significantly less neck gripping, mounting and intromittive behavior than intact males which received empty capsules, although the ATD-induced reductions in behavior were not as large as those seen after castration. ATD had no effect on mating behavior in castrated males. As reported in another publication, brain aromatase activity was significantly reduced in both the intact and castrated males treated with ATD in the present study. Plasma estradiol (E2) levels were uniformly low in intact and castrated males, regardless of whether they received ATD or no steroid. As expected, plasma testosterone (T) levels were significantly lower in castrated than in intact males, and ATD treatment did not affect these values. These results suggest that E2 formed via the neural aromatization of T contributes to the activation of masculine sexual behavior in intact male ferrets in breeding condition.

Androstatrienes↗
PubMed1986

Characterization of the mechanical behavior of isolated papillary muscle preparations of the ferret.

The characteristics of isometric and isotonic contraction were studied in isolated papillary muscle preparations from the right ventricle of the ferret and compared with those previously reported for comparable preparations from cat and rat. The effects of stimulation rate, temperature, extracellular calcium concentration, caffeine, verapamil, and ouabain were measured. Afterloaded contractions and load clamps were used to study the mechanics of relaxation. The contractile characteristics of ferret papillary muscle preparation appear to be intermediate in many respects between those reported for cat and rat preparations.

Animals↗
PubMed1988

The anesthetized ferret, an in vivo model for evaluating inotropic activity: effects of milrinone and anagrelide.

The anesthetized ferret model is introduced as an in vivo acute model for evaluating inotropic effects of new cardiovascular compounds. The effects of anagrelide and milrinone were compared to vehicle. Validation was accomplished using intravenous isoproterenol, which elicited a dose-dependent inotropic response. This suggests that the anesthetized ferret model is both reproducible and dependable. Additionally, in vivo inotropic activity can be assessed on small amounts of compound in a relatively inexpensive species.

Animals↗
PubMed1990

Use of the ferret for a myocardial ischemia/salvage model.

Exploratory work was undertaken in the anesthetized ferret to determine if it is an applicable species for use as an in vivo ischemic model and suitable for recovery surgical procedures. Experimental protocols utilizing varying combinations of left anterior descending (LAD) coronary artery occlusion (30, 60, 90 min) and reperfusion (4, 6, 18-24 hr) were evaluated. The results indicated that a 90-min/6-hr combination led to the production of an infarct equivalent, or slightly greater, in size to that observed following coronary artery occlusion either with and without reflow during an 18-24-hr recovery period prior to sacrifice. A combination of 90 min occlusion/4 hr reperfusion yielded an infarct area ca. 50% of that associated with 6 hr interval of reflow. An occlusive interval of 60 min or less combined with any reperfusion interval lack reproducibility. The administration of saline in varying volumes by different routes (IV versus left atrial) had no influence on either the absolute or, more especially, the relative (i.e., as a percent of left ventricle) tissue damage provoked by a 90-min/6-hr occlusion/reperfusion maneuver of the LAD coronary artery. When evaluated as a reference standard, superoxide dismutase (SOD) infused via the left atrium at a dose of 5 mg/kg afforded a 36% reduction in the area of ischemic damage in this model. These studies demonstrated that the ferret represents a useful species for initial, rapid, and economic--both in terms of cost and drug substance utilization--in vivo myocardial salvage screening assessments. The model permits an interpretation of potential test agent efficacy, dosage requirements, and hemodynamic actions, and it is suitable for basing a go/no-go decision that continued experimental development in more labor intense preparations is warranted.

Animals↗
PubMed1990

Immunological detection of cat uterine proteins in ferrets, dogs and baboons.

In the cat, a high molecular weight (greater than 320 kDa) estrogen (E2)-dependent protein (CUPED) and a group of low molecular weight (28 kDa, 36 kDa, 41 kDa) progesterone (P)-dependent proteins (PDP) are synthesized by the epithelial cells of the deep uterine glands and secreted into the lumen. The present study was designed to investigate the possibility that other species synthesize proteins similar to CUPED and PDP in response to steroids. Uterine flushings and media from cultured endometrial explants obtained from E2 or P dominated animals were analyzed on Western blots for the presence of proteins which cross-react with antibodies raised against CUPED and PDP. CUPED antibody immunoreacted with a protein band at approximately the same molecular weight as CUPED in the media and flushings from E2-treated ferret, dog and baboon, but not from rat, mouse or hamster. In the cat, ferret and dog, specific immunocytochemical staining was observed in the apical portion of the secretory cells. In the baboon, staining was observed in both the basal and apical areas of the epithelial cells. The presence of CUPED in the uterine lumen during the E2-dominated phase of the reproductive cycle in several species suggests that CUPED may play a general role in providing the necessary biochemical milieu for reproductive success. The PDP antibody did not cross-react with proteins in the media of species other than cat, and therefore may be unique to the cat.

Animals↗
PubMed1992

Distributions of interstitial cells of Cajal in stomach and colon of cat, dog, ferret, opossum, rat, guinea pig and rabbit.

Electrical slow waves vary in prominence from one location to another in stomach and colon. If interstitial cells of Cajal are involved in generation of the slow waves, they might be more abundant in regions where slow waves are prominent than in regions where slow waves are small or absent. We calculated the density of distribution of interstitial cells of Cajal in colon and stomach of cat, dog, ferret, guinea pig, opossum, rabbit, and rat, using the zinc iodide-osmic acid reaction for light microscopy. The cells in the stomach were concentrated in the myenteric plexus and in the circular muscle layer. Along the greater curvature, cells were relatively sparse in the fundus, more frequent in the corpus and densest in the antrum. Along the lesser curvature, they were denser distally than proximally in all species except guinea pig. In the colon most cells lay with an axonal network at the circular muscle-submucosal interface. The axons were sparse in the cecum but uniformly conspicuous from the ileocolonic junction to the internal and sphincter. The density of the interstitial cells of Cajal in cat, dog, opossum, and rabbit rose from a relatively low level in the cecum to a maximum in the mid-colon, declining toward the rectum. In guinea pig, rat, and ferret, the levels throughout the most proximal colon were high. Since gastric slow waves are absent from the fundus, diminutive in the body, and prominent in the antrum, the density of interstitial cells of Cajal in the stomach roughly parallels the prominence of slow waves. Colonic slow waves are most prominent in the right colon and mid-colon, and so the density distribution of interstitial cells of Cajal in the colon also roughly parallels the prominence of slow waves.

Animals↗
PubMed1987

Evidence for a multiple innervation of cerebellar Purkinje cells by climbing fibers in adult ferrets infected at birth by a mink enteritis virus.

Newborn ferrets were inoculated with Mink Enteritis virus (parvovirus). They developed a cerebellar hypoplasia and presented severe ataxia. Electrophysiological study by intracellular recordings in the cerebellar cortex demonstrates that in these ferrets, like in other mammals, Purkinje cells deprived from granule cell input during development remain multiply innervated by climbing fibers in the adult.

Animals↗
PubMed1990

Auditory brainstem of the ferret: bilateral cochlear lesions in infancy do not affect the number of neurons projecting from the cochlear nucleus to the inferior colliculus.

Unilateral cochlear removal in infancy produces a number of changes in the structure and physiology of the central auditory system. To test the role that interaural competition plays in this plasticity, ferrets were reared with bilateral cochlear removals from the fourth postnatal week; before the time of the normal onset of auditory function. The totality of the removals was confirmed using brainstem response audiometry and cochlear histology. Following 3-month survival, the animals were injected with wheatgerm horseradish peroxidase in the left inferior colliculus. Retrogradely labeled neurons in the cochlear nucleus on each side were counted. Neither the absolute number nor the bilateral symmetry of the labeled neurons differed significantly from normal adult ferrets. Thus, bilateral cochlear removal does not produce the same change in brainstem connections as unilateral removal or unilateral conductive hearing loss. The results are consistent with the competitive hypothesis.

Animals↗
PubMed1992

Rapid development of the auditory brainstem response threshold in individual ferrets.

The development of the ferret auditory system was examined using the auditory brainstem response (ABR). Longitudinal recordings were obtained under short-acting anaesthesia from individual animals at 4-h or 24-h intervals. Particular attention was focused on the period from postnatal day (P) 26 to P32 when the ferret auditory system becomes functional. ABR thresholds to click stimuli presented in a free-field were found to decline precipitously within a 4-h period during the first 24 h following initial responsiveness. Latencies of waves I and IV of the ABR also declined significantly during this period, but the 'central conduction time' remained stable. A temporal correlation was observed between the time of the precipitous threshold decline and the time of opening of the external ear canal. No changes in cochlear anatomy were observed during this time. We suggest that the opening of the ear canal and/or the clearance of fluid from the middle ear explain the major change in threshold of hearing following onset of function.

Aging↗
PubMed1982

The inadequacy of rectal temperature measurements for assessing the effects of antiviral drugs on influenza virus infection of ferrets.

From 6 experiments in which 99 ferrets were infected with influenza virus A/Finland/74 and treated with various agents which suppress virus shedding and other parameters of infection, we assessed whether rectal temperature correlated with nasal virus shedding. A number of temperature and virus-shedding related parameters were determined for each experiment but statistical analysis showed little correlation between them, although an elevated temperature occurred at some time after infection. The pooled data also suggested that temperature and virus shedding parameters are not clearly related. The analysis indicates that intermittent rectal temperature measurements are unsatisfactory for determining the efficacy of anti-influenza agents in ferrets.

Animals↗
PubMed1986

Molecular studies of the differential replication at pyrexial temperatures of two influenza viruses differing in virulence for ferrets.

Replication of a virulent clone (7a) of the reassortant influenza virus A/Puerto Rico/8/34-A/England/939/69 (H3N2) in ferret nasal turbinate tissue is less affected than that of an attenuated clone (64d) by temperatures which occur during pyrexia in ferrets. This is a factor which contributes to the difference in virulence of the two clones. The differential replication of the two clones at pyrexial temperatures has been reproduced in allantois-on-shell (egg-bit) cultures, and the synthesis of viral polypeptides and RNA species examined. This virus-host system was chosen because it was more convenient to use than organ cultures but, like the latter, might provide information relevant to the in vivo situation. With this system it was not possible to achieve single cycle replication: the observed effects are cumulative over several (2 to 3) cycles of replication (24 h) and therefore conclusions from them may not be as definitive as those from single cycle conditions. However, in cells infected with clone 64d both A(+) cRNA and polypeptide synthesis were little affected at 40 degrees C but levels were decreased by about 70-80% at 41 degrees C; A(+) cRNA and polypeptide levels were unaffected even at 41 degrees C with clone 7a. These reductions seem insufficient to account for the 10-fold reduction in infectious yields of clone 64d at 40 degrees C or the 100-fold and 10-fold reductions in yields of clones 64d and 7a respectively at 41 degrees C. There was no evidence of increased production of non-infectious virus at elevated temperatures by either clone. Levels of vRNA were considerably reduced at 40 and 41 degrees C for both clones, but the levels were considerably greater at all temperatures in clone 7a-infected cells than in those infected with clone 64d; vRNA levels were higher for clone 7a at 41 degrees C than for clone 64d at 37 degrees C. The different levels of vRNA do not reflect differences in the availability of template A(-) cRNAs since levels of these were similar for both clones at 37 and 40 degrees C and only reduced for clone 64d at 41 degrees C. Although the interpretation of these data is complicated by multiple cycles of replication it appears that limited availability of vRNA could be an important constraint on the ability of clone 64d to replicate at pyrexial temperatures.

Animals↗
PubMed1991

Variable effects of soman on macromolecular secretion by ferret trachea.

The purpose of this study was to examine the effect of the anticholinesterase agent, soman, on macromolecular secretion by ferret trachea, in vitro. We mounted pieces of ferret trachea in Ussing-type chambers. Secreted sulfated macromolecules were radiolabeled by adding 500 microCi of 35SO4 to the submucosal medium and incubating for 17 hr. Soman added to the submucosal side produced a concentration-dependent increase in radiolabeled macromolecular release with a maximal secretory response (mean +/- SD) of 202 +/- 125% (n = 8) relative to the basal secretion rate at a concentration of 10(-7) M. The addition of either 10(-6) M pralidoxime (acetylcholinesterase reactivator) or 10(-6) M atropine blocked the response to 10(-7) M soman. At soman concentrations greater than 10(-7) M, secretion rate decreased and was not significantly different from basal secretion. Additional experiments utilizing acetylcholine and the acetylcholinesterase inhibitor, physostigmine, suggest that inhibition of secretion by high concentrations of soman may be due to a secondary antagonistic effect of soman on muscarinic receptors.

Acetylcholine↗