No abstract available.
Chinchilla* ; Neurons*

No abstract available.
Chinchilla* ; Vestibular Nerve*

No abstract available.
Chinchilla* ; Vestibular Nerve* ; Vestibular Nuclei*

BACKGROUND AND OBJECTIVES: TElectrical stimulation has been used for several vestibular tests, such as galvanic body sway tests and galvanic evoked myogenic responses. In these tests, small amplitude galvanic currents are delivered transcuta-neously to the vestibular afferents. It is noted, however, there has not been any reports concerning the difference between the afferent-responses to transcutaneous and perilymphatic galvanic stimulations. SUBJECTS AND METHOD: We used anesthetized chinchillas and made extracellular recordings from vestibular afferents. Galvanic currents were applied transcutaneously and perilymphatically, and we compared the responses of vestibular afferents at each condition. RESULTS: Irregular afferents had characteristically large galvanic responses and regular afferents had characteristically small responses. For regularly discharging afferents, the mean galvanic sensitivities to anodal/cathodal currents were 0.22+/-0.23/0.23+/-0.17 spikes.s-1/microA (n=17), and 1.64+/-2.18/1.88+/-2.07 spikes.s-1/microA for irregularly discharging afferents (n=11). The estimated amplitude of perilymphatic galvanic stimulus, which showed the same changes of the resting rates by transcutaneous galvanic stimulation using 1 mA, were 65.0/66.0 microA for regularly and irregularly discharging afferents, respectively. CONCLUSION: These findings suggest that transcutaneous galvanic stimulation affects irregular afferents more than regular afferents perilymphatic galvanic stimulation. And more than 1.54 mA amplitude of transcutaneous galvanic stimulation is needed to ablate irregularly discharging afferents functionally.
Chinchilla ; Electric Stimulation* ; Otolithic Membrane ; Semicircular Canals ; Transcutaneous Electric Nerve Stimulation*

BACKGROUNDS AND OBJECTIVES: We developed a method of intraotic treatment using gentamicin (GM) in chinchillas. MATERIALS AND METHOD: An osmotic pump, connected near the round window by a Teflon tube (0.13mm ID X 0.18mm OD) through an opening in the scala tympani, continuously perfused 12microliter of GM per day for a week. In the three experimental groups (n=12), each animal was treated with a total dose of 0.1mg of GM for a week. Animals in the control group (n=4) were immediately sacrificed after perfusion with saline for a week. RESULTS: In the control group, there was no damage in any of the hair cells. In the treatment group, the hair cells were more severely damaged at 4 weeks than at 1 week. The outer hair cells were more sensitive to GM than the inner hair cells. Among the outer hair cells, the first rows were damaged first. The basal part of cochlea was damaged earlier than the apical. The ototoxic effect continued even after perfusion had ceased. CONCLUSIONS: This pump system limits drug distribution to the target tissue, minimizing systemic side effects while permitting precise control of delivery rate, volume, concentration and duration.
Animals ; Chinchilla* ; Cochlea ; Gentamicins* ; Hair ; Microscopy, Electron, Scanning ; Perfusion ; Polytetrafluoroethylene ; Scala Tympani

BACKGROUND AND OBJECTIVES: Aminoglycoside antibiotics are toxic to hair cells of the inner ear. Recently, intratympanic gentamicin injection is widely accepted as a treatment modality for Meniere's disease. SUBJECTS AND METHOD: We treated anesthetized chinchillas with one injection of gentamicin into the middle ear and made extracellular recordings from afferents after three to four weeks. RESULTS: The spontaneous firing rate of regular and irregular afferents was lower (p<0.05) on the treated side than on the untreated side. The relative proportions of regular, intermediate, and irregular afferents did not change after treatment. The majority of the treated afferents did not significantly respond to rotation, and those that did respond had abnormally low levels of sensitivity. Sensitivity to externally applied galvanic currents was unaffected. CONCLUSION: These findings suggest that a single intratympanic gentamicin injection preserves enough hair cell synaptic activity to drive the spontaneous activity of vestibular afferents, and does not damage the afferent spike initiation zones.
Anti-Bacterial Agents ; Chinchilla ; Ear, Inner ; Ear, Middle ; Electrophysiology ; Fires ; Gentamicins* ; Hair ; Meniere Disease

BACKGROUND AND OBJECTIVES: Partial resection of vestibular labyrinth has a great interest to all otologists and neurotologists. Various materials have been applied for occlusion of semicircular canals with different postoperative hearing results. However, the most suitable material for occlusion has not determined yet. Authors tried to compare the occlusion materials through a histologic study in experimental animals. MATERIALS AND METHOD: The lateral semicircular canal (LSCC) was transected, and the canal lumens were occluded with bone dust, muscle or bone wax in chinchillas. Thresholds for the auditory brainstem response (ABR) were measured after occlusion for two months, and histologic changes of LSCC were observed. RESULTS: Periosteal osteogenesis at the surgical defects of LSCC and perilymphatic fibrosis in the canal lumen were remarkable in the bone dust and muscle groups. The bone wax group showed minimal osteoneogenesis and some degree of perilymphatic inflammation (serous labyrinthitis). CONCLUSION: This study showed complications of each occlusion material. The proper selection of an occlusion material based on its characteristics seems to be important for a successful partial labyrinthectomy.
Animals ; Chinchilla* ; Dust ; Evoked Potentials, Auditory, Brain Stem ; Fibrosis ; Hearing ; Inflammation ; Osteogenesis ; Semicircular Canals* ; Vestibule, Labyrinth

Feline endometrial adenocarcinomas are uncommon malignant neoplasms that have been poorly characterized to date. In this study, we describe a uterine adenocarcinoma in a Persian cat with feline leukemia virus infection. At the time of presentation, the cat, a female Persian chinchilla, was 2 years old. The cat underwent surgical ovariohystectomy. A cross-section of the uterine wall revealed a thickened uterine horn. The cat tested positive for feline leukemia virus as detected by polymerase chain reaction. Histopathological examination revealed uterine adenocarcinoma that had metastasized to the omentum, resulting in thickening and the formation of inflammatory lesions. Based on the histopathological findings, this case was diagnosed as a uterine adenocarcinoma with abdominal metastasis. To the best of our knowledge, this is the first report of a uterine adenocarcinoma with feline leukemia virus infection.
Adenocarcinoma ; Animals ; Cats ; Chinchilla ; Female ; Horns ; Humans ; Leukemia Virus, Feline ; Leukemia, Feline ; Neoplasm Metastasis ; Omentum ; Polymerase Chain Reaction ; Uterus

A 5-year-old castrated male Chinchilla Persian cat weighing 4.84 kg was referred for hematuria. The cat had a history of urethrostomy and bacterial cystitis. In urine culture, Candida glabrata was cultured on Sabouraud dextrose agar. Based on these results, the cat was diagnosed with Candida cystitis. Subsequently, oral administration of fluconazole was initiated. Urine culture was negative at 31 days after administration. This case describes the diagnosis and treatment of Candida glabrata infection of urinary bladder in a cat with a history of urethrostomy.
Administration, Oral ; Agar ; Animals ; Candida glabrata* ; Candida* ; Cats* ; Child, Preschool ; Chinchilla* ; Cystitis ; Diagnosis ; Fluconazole ; Glucose ; Hematuria ; Humans ; Male ; Urinary Bladder*

Digestive disorders caused by sudden changes in diet or inappropriate diet are among the most common disorders of the digestive system. Cecal or intestinal tympany, one consequence of inappropriate diet, is characterized by the accumulation of gases, marked distension of the cecum and colon and the induction of inflammatory processes. To know the effects of intestinal tympany on the enteric plexuses, we developed a method of experimental tympanic colic (TC) in the Chinchilla lanigera. This species was used in view of its susceptibility to TC. TC was induced with a diet rich in alfalfa associated with grain overload for two weeks. Physical and clinical examination including the von Frey test confirmed the diagnosis. The chinchillas with acute abdomen were treated with 1% ketoprofen and resumption of a balanced diet. Necropsy and histopathological analysis showed tympany-induced alterations mainly in the cecum and colon. After treatment, the control conditions were restored. The TC protocol is proposed as an experimental approach designed to aid the study of the effects of acute intestinal inflammation and obstruction caused by an inappropriate diet.
Abdomen, Acute ; Cecum ; Edible Grain ; Chinchilla* ; Colic* ; Colon ; Diagnosis ; Diet ; Digestive System ; Gases ; Inflammation ; Ketoprofen ; Medicago sativa ; Models, Theoretical*