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The contribution of sensory experience to the maturation of orientation selectivity in ferret visual cortex.

Sensory experience begins when neural circuits in the cerebral cortex are still immature; however, the contribution of experience to cortical maturation remains unclear. In the visual cortex, the selectivity of neurons for oriented stimuli at the time of eye opening is poor and increases dramatically after the onset of visual experience. Here we investigate whether visual experience has a significant role in the maturation of orientation selectivity and underlying cortical circuits using two forms of deprivation: dark rearing, which completely eliminates experience, and binocular lid suture, which alters the pattern of sensory driven activity. Orientation maps were present in dark-reared ferrets, but fully mature levels of tuning were never attained. In contrast, only rudimentary levels of orientation selectivity were observed in lid-sutured ferrets. Despite these differences, horizontal connections in both groups were less extensive and less clustered than normal, suggesting that long-range cortical processing is not essential for the expression of orientation selectivity, but may be needed for the full maturation of tuning. Thus, experience is beneficial or highly detrimental to cortical maturation, depending on the pattern of sensory driven activity.

Animals↗

Husbandry and management of the domestic ferret.

Domesticated thousands of years ago and used for their hunting skills, ferrets have in more recent times proven to be excellent models for several fields of study, including virology and immunology. The author reviews the basic care and management of ferrets in the animal facility.

Anesthesia↗

Dexamethasone can potentiate the anti-emetic action of a 5HT3 receptor antagonist on cyclophosphamide induced vomiting in the ferret.

A new group of selective 5HT3 antagonists are proving to be effective anti-emetics for cytotoxic and radiation induced vomiting in both animal models and man. Current anti-emetic regimens often benefit from combination therapy, in particular the efficacy of metoclopramide (which can be a weak 5HT3 antagonist), can be improved by combination with dexamethasone, another anti-emetic. Hence it was of interest to evaluate whether a 5HT3 receptor antagonist GR38032F could be improved by combination with dexamethasone. Vomiting induced by cyclophosphamide in the ferret was observed after pre-treatment with dexamethasone alone or in combination with GR38032F. Animals were also observed for signs of 'nausea'. Dexamethasone alone proved a weak anti-emetic in this system but did have significant effects on 'nausea'. GR38032F has previously been shown to be capable of totally controlling emesis due to cyclophosphamide in the ferret. Here a dose of GR38032F that is not 100% effective was employed; this was shown to have effects on 'nausea' but most interestingly its anti-emetic action was increased by combination with dexamethasone. This may be important for the minority of patients whose vomiting is not completely controlled by GR38032F alone.

Animals↗

Blood collection from the cranial vena cava of the ferret.

The domestic ferret, though not as common a laboratory animal as the rat or mouse, serves as a model in critical research areas, including influenza biology and vaccine development. Studies involving ferrets necessitate knowledge of proper blood collection methods, such as cranial vena cava puncture.

Animals↗

Neuroregulation of mucus secretion by opioid receptors and K(ATP) and BK(Ca) channels in ferret trachea in vitro.

1. Opioid agonists inhibit neurogenic mucus secretion in the airways. The mechanism of the inhibition is unknown but may be via opening of potassium (K+) channels. We studied the effect on neurogenic secretion in ferret trachea in vitro of the OP1 receptor (formerly known as delta opioid receptor) agonist [D-Pen2,5]enkephalin (DPDPE), the OP2 receptor (formely kappa) agonist U-50,488H, the OP3 receptor (formerly micro) agonist [D-Ala2, N-Me-Phe, Gly-ol5]enkephalin (DAMGO), the ATP-sensitive K+ (K(ATP)) channel inhibitor glibenclamide, the large conductance calcium activated K+ (BK(Ca)) channel blocker iberiotoxin, the small conductance K(Ca) (SK(Ca)) channel blocker apamin, the K(ATP) channel opener levcromakalim, a putative K(ATP) channel opener RS 91309, and the BK(Ca) channel opener NS 1619. Secretion was quantified by use of 35SO4 as a mucus marker. 2. Electrical stimulation increased tracheal secretion by up to 40 fold above sham-stimulated levels. DAMGO or DPDPE (10 microm each) significantly inhibited neurogenic secretion by 85% and 77%, respectively, effects which were reversed by naloxone. U-50,488H had no significant inhibitory effect on neurogenic secretion, and none of the opioids had any effect on ACh-induced or [Sar9]substance P-induced secretion. 3. Inhibition of neurogenic secretion by DAMGO or DPDPE was reversed by iberiotoxin (3 microM) but not by either glibenclamide or apamin (0.1 microM each). Iberiotoxin alone did not affect the neurogenic secretory response. 4. Levcromakalim, RS 91309 or NS 1619 (3 nM-3 microM) inhibited neurogenic secretion with maximal inhibitions at 3 microM of 68%, 72% and 96%, respectively. Neither levcromakalim nor RS 91309 at any concentration tested significantly inhibited acetylcholine (ACh)-induced secretion, whereas inhibition (60%) was achieved at the highest concentration of NS 1619, a response which was blocked by iberiotoxin. 5. Inhibition of neurogenic secretion by levcromakalim (3 microM) or RS 91309 (30 nM) was inhibited by glibenclamide but not by iberiotoxin. In contrast, inhibition by NS 1619 (30 nM and 3 microM) was blocked by iberiotoxin but not by glibenclamide. 6. We conclude that, in ferret trachea in vitro, OP1 or OP3 opioid receptors inhibit neurogenic mucus secretion at a prejunctional site and that the mechanism of the inhibition is via opening of BK(Ca) channels. Direct opening of BK(Ca) channels or K(ATP) channels also inhibits neurogenic mucus secretion. In addition, opening of BK(Ca) channels inhibits ACh-evoked secretion of mucus. Drugs which open BK(Ca) channels may have therapeutic anti-secretory activity in bronchial diseases in which neurogenic mechanisms and mucus hypersecretion are implicated in pathophysiology, for example asthma and chronic bronchitis.

Adenosine Triphosphate↗

Effect of vasoactive intestinal peptide (VIP)-related peptides on cholinergic neurogenic and direct mucus secretion in ferret trachea in vitro.

1 We investigated whether vasoactive intestinal peptide (VIP) and its related peptides, pituitary adenylate cyclase activating peptide (PACAP) and secretin, regulate cholinergic neural mucus secretion in ferret trachea in vitro, using 35SO4 as a mucus marker. We also studied the interaction between VIP and secretin on cholinergic mucus output. 2 VIP (1 and 10 microM) increased secretion, whereas neither PACAP1 - 27, PACAP1 - 38 nor secretin (up to 10 microM) increased mucus output. In contrast, VIP, PACAP1 - 27 and PACAP1 - 38 concentration-dependently inhibited cholinergic neural secretion, with an order of potency of VIP>PACAP 1 - 38>PACAP1 - 27. Neither PACAP1 - 27 nor PACAP1 - 38 altered the secretion induced by acetylcholine (ACh). 3 Secretin increased cholinergic neural secretion with a maximal increase of 190% at 1 microM. This potentiation was blocked by VIP or atropine. Similarly, secretin (1 microM) potentiated VIP (1 microM)-induced mucus output by 160%. Secretin did not alter exogenous ACh-induced secretion. VIP vs secretin competition curves suggested these two peptides were competing reversibly for the same receptor. 4 We conclude that, in ferret trachea in vitro, VIP and PACAPs inhibit cholinergic neural secretion via pre-junctional modulation of cholinergic neurotransmission. VIP and secretin compete for the same receptor, possibly a VIP1 receptor, at which secretin may be a receptor antagonist.

Acetylcholine↗

Comparison of the affinity of beta-blockers for two states of the beta 1-adrenoceptor in ferret ventricular myocardium.

We compared the potency of 11 clinically available beta-blockers as antagonists of the positive inotropic effects of (-)-isoprenaline and CGP12177 on ferret ventricular myocardium. (-)-CGP12177, (-)-pindolol and (-)-alprenolol were non-conventional partial agonists with intrinsic activity of 0.7, 0.2 and 0.1 respectively. All beta-blockers antagonized in a concentration-dependent and surmountable manner the positive inotropic effects of both (-)-isoprenaline and CGP12177. The potency of each beta-blocker was consistently higher against (-)-isoprenaline than against CGP12177. Two groups of beta-blockers were identified. In one group the difference between the pK(B) values of blockade against (-)-isoprenaline and CGP12177 was 1.1 - 1.6 log units ((-)-alprenolol, (-)-pindolol, (-)-bupranolol, nadolol and carvedilol). In the other group the pK(B) difference was of 2.1 - 3.0 log units ((-)-atenolol, metoprolol, bisoprolol, sotalol, (-)-propranolol and (-)-timolol). The beta-blockers competed with (-)-[(125)I]-cyanopindolol for binding to ventricular beta(1)-adrenoceptors. The binding affinities correlated with the corresponding blocking potencies against (-)-isoprenaline. On average the pK(i) values were 0.5 log units smaller than the pK(B) values against (-)-isoprenaline but 1.6 log units greater than the pK(B) values against CGP12177. In ferret ventricle the effects of (-)-isoprenaline appear to be antagonized by beta-blockers through the state of the beta(1)-adrenoceptor for which (-)-[(125)I]-cyanopindolol and beta-blockers have high affinity. The cardiostimulant effects of CGP12177 appear to be mediated through a low-affinity state of the beta(1)-adrenoceptor for which beta-blockers have low affinity.

Adrenergic beta-1 Receptor Agonists↗

The temporal pattern of mating-induced immediate-early gene product immunoreactivity in LHRH and non-LHRH neurons of the estrous ferret forebrain.

The mating-induced preovulatory surge of luteinizing hormone (LH) lasts for at least 12 h in the female ferret. This prolonged increase in circulating LH is presumably accompanied by a corresponding elevation in the activity and output of luteinizing hormone-releasing hormone (LHRH) neurons projecting to the hypothalamic-hypophyseal portal blood vessels and adenohypophysis. We used the protein products of the immediate early genes (IEGs) c-fos, and c-jun as markers of neural activation in order to determine whether a sub-population of LHRH neurons is differentially activated by mating and whether non-LHRH neurons in specific forebrain regions are selectively activated at different times during the mating-induced preovulatory LH surge. In Experiment 1, estrous female ferrets were perfused 0.5, 1.5, 3.0, 6.0 or 12.0 h after receiving one 5-min intromission from a male or after being placed alone in a testing cage for 20 min. Fos-like immunoreactivity (Fos-IR; Oncogene Ab-2 antiserum) and LHRH-like immunoreactivity (LHRH-IR; LR-1 antiserum) were visualized. The percentage of Fos-IR LHRH neurons was significantly augmented 1.5 h after mating but had returned to basal levels by 3.0 h. The double-labeled LHRH neurons were concentrated in the caudal medio-basal hypothalamus. In non-LHRH neurons the number of Fos-IR neural nuclei was significantly increased by mating in the medial preoptic area (MPOA), bed nucleus of the stria terminalis (BNST), medial amygdala (MA), ventrolateral hypothalamus (VLH), and midbrain central tegmental field (CTF) 1.5 h after mating but, as in LHRH neurons, had returned to basal levels by 3.0 h. In Experiment 2, estrous females were perfused 1.5 h or 8.0 h after either receiving one 5-min intromission or being placed alone in a testing cage, and the brains were processed for LHRH and c-Fos-like (DCH-1, Dr Gerard Evan), c-Jun-like (Jun-IR; Oncogene Ab-2) or Egr-1-like (Egr-IR; Santa Cruz) immunoreactivity. The percentage of LHRH neurons colabeled with both Fos-IR and Jun-IR was significantly greater in the 1.5 h group than in the unpaired group. Again, the induction of these IEG products occurred in LHRH neurons in the caudal medio-basal hypothalamus. Mating significantly increased the number of Fos-IR non-LHRH neural nuclei in the MPOA, BNST, MA, VMH and CTF, as well as the number of Egr-IR nuclei in the MPOA, BNST and MA in the 1.5 h group. By contrast, the number of Jun-IR non-LHRH neurons was unaffected by mating. In these Experiments we have identified a sub-population of LHRH neurons which, using Fos and Jun as markers of neural activation, is activated by mating and may be differentially involved in the generation of the preovulatory LH surge. Although the LHRH system is presumably activated throughout the duration of the 12 h preovulatory LH surge, c-Fos and c-Jun immunoreactivity in LHRH neurons is augmented only transiently. Fos-IR and Egr-IR in non-LHRH neurons show a similar time-course. Together, these results suggest that the presence of augmented levels of these proteins is not required for the maintenance or termination of the preovulatory output of LHRH.

Animals↗

Pyloric motor response to central and peripheral nitric oxide in the ferret.

This study has investigated the relative importance of central nervous and peripheral nitroxidergic mechanisms in the control of pyloric motility. In 10 urethane-anaesthetized ferrets, drugs were administered directly to the CNS via a 0.5-mm-diameter cannula inserted into the 4th ventricle, approximately at the obex. Drugs were also given directly to the upper GI tract by close intra-arterial (i.a.) injection at the coeliac axis. Antropyloroduodenal pressures were recorded with a five-channel sleeve/sidehole micromanometric assembly (1.35 x 1.75 mm o.d.), which was introduced via the duodenum. Pyloric motility was stimulated throughout the main part of each study with a continuous i.v. infusion of CCK-8 (30 pmol min-1). This infusion produced an immediate and sustained increase in tonic and phasic pyloric activity, and sustained abolition of antral pressure waves. CCK-8 also induced a duodenal motor response, but this was short-lived (11.4 +/- 7.9 min). Coeliac axis injection of the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) decreased phasic pyloric activity (from 330 +/- 35 to 148 +/- 21 mmHg min-1 after SNAP 5 micrograms, P < 0.01). By comparison central SNAP administration over the same dose range had no effect on CCK-stimulated pyloric motlity. Inhibition of endogenous NO synthase with L-Nitro Arginine Methyl Ester (L-NAME, 100 mg kg-1 close i.a.) caused a marked increase of phase pyloric motor activity from 349 +/- 59 to 1044 +/- 140 mmHg min-1 (P < 0.01). In addition, SNAP caused marked stimulation of pyloric tone from 2.6 +/- 0.5 to 13.1 +/- 2.8 mmHg (P < 0.01). Central nervous administration of L-NAME caused modest enhancement of phasic pyloric activity (248 +/- 31 to 283 +/- 32 mmHg min-1 P < 0.05) and pyloric tone (2.6 +/- 0.5 to 3.7 +/- 0.7 mmHg, P < 0.05). Our data indicate that motor activity of the ferret pylorus is potently modulated by NO released within the upper gut. Additionally, there is potential for modulation of pyloric motility by central nervous system production of NO.

Animals↗

Presence of putative neurotransmitters in the myenteric plexus of the gastrointestinal tract and in the musculature of the urinary bladder of the ferret.

The innervation of the musculature in the ferret stomach, ileum, colon and urinary bladder was investigated using immunohistochemistry in noncolchicin-treated tissues. In the gastrointestinal tract two main subpopulations of myenteric neurones were found: cholinergic neurones expressing choline acetyltransferase (ChAT), which made up 68, 67 and 67% of the neurones in the stomach, ileum and colon, respectively, and nitrergic neurones containing nitric oxide synthase and NADPH-diaphorase (stomach: 23%, ileum: 21%, colon: 26%). In the stomach, cholinergic neurones expressed substance P (SP, 2% of all neurones), dopamine-beta-hydroxylase (DBH, 19%) but not tyrosine hydroxylase (TH) or vasoactive intestinal polypeptide (VIP), while nitrergic neurones contained VIP and neuropeptide Y (NPY). TH- but not DBH-immunoreactivity was observed in 4% of gastric neurones. Intense immunoreactivity in the musculature suggests that part of ChAT/SP- and NOS/NPY/VIP-positive neurones function as motorneurones. In the ileum, a high number (32%) of DBH-positive neurones was demonstrated. About half of the SP-positive neurones in the ileum also contained calcitonin gene-related peptide (CGRP). In the urinary bladder, only few intramural ganglia were observed. The smooth muscle was densely innervated by ChAT, NPY and DBH immunoreactive fibres. The data showed that the innervation of the ferret viscera exhibited similarities but also differences as compared with other mammalian species. Some of the chemical coding of myenteric neurones is remarkably similar to that observed in other mammals.

Animals↗

Hypereosinophilic syndrome with Hodgkin's-like lymphoma in a ferret.

Hodgkin's-like lymphoma involving the lung, mediastinum, liver, kidneys and mesenteric lymph nodes was diagnosed in a ferret. The diagnosis was based on the presence of an admixture of CD3+ small lymphocytes with smaller numbers of macrophages, eosinophils, and large, pleomorphic, frequently multinucleated, Reed-Sternberg-like cells which were immunoreactive to BLA.36 monoclonal antibody. In addition, the liver, pancreas, small intestine and lungs were infiltrated with moderate to large numbers of eosinophils, forming eosinophilic granulomas with occasional deposition of Splendore-Hoeppli material, supporting a diagnosis of hypereosinophilic syndrome. The concurrent diagnosis of hypereosinophilic syndrome and Hodgkin's-like lymphoma in this ferret provides further support to the concept that, in animals, multisystemic eosinophilic infiltrates may be caused by the abnormal proliferation of T lymphocytes, as has been demonstrated in man.

Animals↗

Developmental patterns of thyroid hormones and testosterone in ferrets.

Plasma levels of thyroxine (T4) and triiodothyronine (T3) were measured in male and female ferrets at regular intervals between postnatal day 20 and 150 as well as in adult animals. In addition, testosterone level in male ferrets was measured. All hormones showed characteristic developmental patterns. There is a T4 maximum prior to a T3 maximum in subadult animals which in both cases surpasses adult levels. Testosterone level shows a different developmental pattern. There is an outstanding peak in subadult males around day 60-80, which, however, is surpassed by adult levels during the mating season.

Animals↗

Bone repair of experimentally induced through-and-through defects by Gore-Tex, Guidor, and Vicryl in ferrets: a pilot study.

OBJECTIVE: The purpose of this pilot study was to evaluate whether improved bone regeneration can be achieved in experimentally induced through-and-through mandibular defects in ferrets and whether there is a quantitative and qualitative difference of regenerated bone with different guided tissue regeneration membranes. STUDY DESIGN: Through-and-through osseous defects were created at the apices of 16 mandibular premolars of 8 ferrets. The transosseous defects were covered with Gore-Tex, Vicryl, or Guidor membranes. As control, the defects were covered with mucoperiosteal flaps without any membranes. RESULTS: The control group showed ingrowth of sulcular epithelium into the defect. The Gore-Tex group showed good bone formation, whereas the Vicryl group showed the highest degree of bone formation. Six weeks after the operation, the defect had nearly completely filled with fibered and lamellar bone. Twelve weeks after the operation, mainly lamellar bone was observed. In contrast, the Guidor group was found to have limited bone regeneration. CONCLUSION: The results of this in vivo study suggest that guided tissue regeneration membranes generally promote and improve bone regeneration in osseous defects of endodontic origin.

Animals↗

Glucose-6-phosphate isomerase is necessary for embryo implantation in the domestic ferret.

The mechanism of implantation in carnivores is poorly understood. However, a previously unidentified 60-kDa protein has been shown to be necessary for embryo implantation in ferrets. Here we identify this protein as glucose-6-phosphate isomerase (GPI). GPI is expressed by the corpus luteum on days 6-9 of pregnancy, the time at which implantation-promoting activity has been found in corpora lutea. Passive immunization against GPI reduced the number of implantation sites in pregnant ferrets in a dose-dependent manner. GPI is a multifunctional protein. Although first identified for its role in glycolysis, GPI has since been implicated in neural growth, lymphocyte maturation, and metastasis. This study demonstrates a previously uncharacterized function of this protein that may represent the natural motility-stimulating activity that has been co-opted by tumor cells.

Amino Acid Sequence↗

Nerve fibers immunoreactive to calcitonin gene-related peptide, substance P, neuropeptide Y, and dopamine beta-hydroxylase in innervated and denervated oral tissues in ferrets.

The effect of sensory and sympathetic denervation on the localization and distribution of nerve fibers immunoreactive (IR) to calcitonin gene-related peptide (CGRP), substance P (SP), neuropeptide Y (NPY), and dopamine beta-hydroxylase (DBH) was studied in the dental pulp, periodontal ligament (PDL), and gingiva in ferrets. Unilateral axotomy was performed by resection of the inferior alveolar nerve (IAN) 10 days before the experiment (Group 1); sympathectomy, by unilateral removal of the cervical ganglion 5 days before the experiments (Group 2). Immunohistochemistry was performed on free-floating sections by the avidin-biotin-peroxidase technique. A considerably higher density of sensory fibers IR to CGRP and SP was found in the dental pulp than in PDL and gingiva. The majority of pulpal fibers were located in the walls of blood vessels. A subodontoblastic network of fibers IR to CGRP and SP was lacking in incisors and canines and was found only in the coronal pulp in premolars and molars. Sympathetic fibers were sparsely distributed in the pulp, and they were mainly confined to large vessels running centrally in the root pulp as well as the larger vessels in apical PDL and alveolar bone. Gingiva was well supplied with CGRP- and SP-IR nerves, and some NPY and DBH fibers were located in association with larger vessels. Round cell-like structures within the basal part of the epithelium were CGRP-IR. Axotomy induced a complete loss of CGRP- and SP-IR fibers in the anterior part of the jaws, whereas sympathectomy caused a reduction, but not a total loss, of NPY- and DBH-IR nerves. It is concluded that, except for some distributional differences, the oral tissues in the ferret have an abundant sensory innervation similar to that found in other species.

Alveolar Process↗

The effects of dietary taurocholate, fat, protein, and carbohydrate on the distribution and fate of dietary beta-carotene in ferrets.

Dietary beta-carotene has been shown to have cancer chemopreventive action on the basis of epidemiologic evidence and studies in animals. Because the anticarcinogenic property of beta-carotene may be exerted per se, it is desirable to achieve the maximum absorption and accumulation of intact beta-carotene in various parts of the body. Therefore the effects of dietary taurocholate, fat, protein, and carbohydrate on the absorption, accumulation, and fate of dietary beta-carotene (3.730 nmol/g diet) in selected tissues of ferrets were explored. Taurocholate (0.2-1.0% wt/wt) and fat (6-23% wt/wt) caused two- to threefold (p < 0.05) increases in the absorption and accumulation of beta-carotene in the liver, lungs, and adipose tissue in a dose-dependent manner. In contrast, neither dietary protein (10-40% wt/wt) nor carbohydrate (25-55% wt/wt) affected the absorption and accumulation of beta-carotene in various tissues. Significantly, taurocholate, 23% fat, or 40% protein also markedly increased the amounts of hepatic retinol and retinyl esters derived from dietary beta-carotene. These results indicate that dietary taurocholate, fat, and high protein have a marked influence on the exposure of beta-carotene to intestinal carotene cleavage enzyme or its activity. Thus an ideal combination of dietary components (wt/wt) in ferrets for the maximal absorption and accumulation of beta-carotene in different tissues is 0.5% taurocholate and 13.4% fat, whereas 1% taurocholate, 23% fat, or 40% protein stimulates its conversion to vitamin A.

Absorption↗

Radiation-induced acute intestinal inflammation differs following total-body versus abdominopelvic irradiation in the ferret.

PURPOSE: The studies were designed to investigate the differences in the intestinal inflammatory response following abdominopelvic or total-body irradiation in a ferret model. MATERIALS AND METHODS: Ferrets were exposed either to total-body or to abdominopelvic gamma-radiation (5 Gy) and various parameters of inflammation studied in the jejunum, ileum and colon 2 and 7 days later. RESULTS: Abdominopelvic and, to a greater extent, total-body irradiation caused weight loss by 7 days. White blood cell counts were reduced in both groups, but more so following total-body irradiation. Myeloperoxidase activity was significantly increased in the ileum 2 days after abdominopelvic irradiation, but it was reduced after total-body irradiation. Total-body irradiation increased tissue prostaglandin E2 levels in all regions at 2 days and decreased jejunal leukotriene B4 levels in the jejunum at both time points. Ileal prostaglandin E2 levels were increased 2 days after abdominopelvic irradiation. Expression of inducible nitric oxide synthase was not altered by either irradiation protocol. CONCLUSIONS: The data show that there are regional differences in the intestinal response to irradiation, depending on whether it was delivered to the whole body or locally to the abdominopelvic region. In particular, the ileum exhibited an acute increase in myeloperoxidase activity following abdominopelvic but not total-body irradiation.

Animals↗

Studies of influenza infection in ferrets by means of fluorescein-labelled antibody. I. The pathogenesis and diagnosis of the disease.

By means of fluorescein-labelled antibody staining, specific influenza viral antigens were seen in both the cytoplasm and the nucleus of infected ciliated epithelial cells covering the nasal turbinates of infected ferrets. Initially, only a small portion of the nasal epithelium showed fluorescence, and no appreciable abnormality of the cells could be detected by hematoxylin and eosin staining. The fluorescence soon spread to involve the entire epithelium, followed by desquamation coinciding with the onset of manifest illness. Pneumonia was seen in some of the infected ferrets, and in them, viral antigens were found in the bronchial epithelium and in the mediastinal lymph nodes. A rise of viral infectivity titer paralleled the observed spread of viral antigens. Many desquamated nasal epithelial cells and macrophages containing antigen were present in nasal smears. The finding would seem to offer a method for the rapid specific diagnosis of influenza infection.

Animals↗