Mammary and reproductive tract tumours and tumour-like lesions of 286 small pet mammals: a retrospective study.

Small mammals are very popular companion animals, and the incidence of particular tumour types in these animals is the subject of extensive research. We carried out a retrospective and comparative analysis of the incidence of reproductive tract and mammary tumours and tumour-like lesions collected from 103 pet rabbits, 75 pet rats, 71 guinea pigs, 12 mice, 11 hamsters, eight African pygmy hedgehogs, four ferrets and two chinchillas. The results indicate that uterine tumours and tumour-like lesions are common in pet rabbits, guinea pigs and African pygmy hedgehogs. In pet rabbits, the most common uterine tumour was endometrial adenocarcinoma, while in guinea pigs benign lesions predominated (ie, leiomyoma, endometrial adenoma, cystic endometrial hyperplasia and deciduoma). Uterine tumours in African pygmy hedgehogs included adenosarcomas and endometrial polyps. Ovarian lesions were found only in guinea pigs (ovarian rete adenomas, rete cysts) and African pygmy hedgehogs (mostly granulosa cell tumours), while testicular tumours were diagnosed in pet rabbits, one pet rat and one guinea pig. Mammary tumours were common in pet rabbits, pet rats, guinea pigs, mice, hamsters and African pygmy hedgehogs. In pet rats, the most common mammary tumour was fibroadenoma, while in other animals carcinomas predominated. In guinea pigs and, to a lesser extent, in pet rats, a significant percentage of mammary tumours occurred in males. Guinea pigs seem to be predisposed to mammary tumours of ductal origin. This study describes for the first time uterine angioleiomyoma in the pet rabbit and mammary spindle cell carcinoma in the Djungarian hamster and chinchilla.

Computed tomography and three dimensional anatomical study of the liver in the chinchilla (Chinchilla lanigera).

Few instances of neoplastic formations in the liver of chinchillas have been found, even though the species is widely used in different scientific experiments. In the present article we investigate the anatomical features of the chinchilla's liver using CT and three dimension (3D) imaging. For the trials we used 12 (six males and six females) clinically healthy chinchillas all at 18 months of age. The animals were positioned in dorsal recumbency. We used Th8 to L2 vertebrae and the sternum as bone markers for the transverse CT study. The investigated anatomical landmarks for the CT coronal study were the vertebrae, costal arch, soft abdominal wall, diaphragm, stomach and the right kidney. 3D reconstructions were accomplished with a specific imaging software. On transverse and coronal CT images, the chinchilla's liver was composed of lobus hepatis sinister lateralis, 'middle lobe'-without proper Latin term in NAV 2017, lobus hepatis dexter and lobus caudatus. The 'middle lobe' was separated into the 'left middle lobe' and the 'right middle lobe'. Lobus hepatis dexter consisted of lobus hepatis dexter medialis and lobus hepatis dexter lateralis. There was an anatomical relation between the liver, fundus ventriculi and corpus ventriculi. Proc. caudatus was in close contact with the right kidney. Vesica fellea was elongated and ellipsoid. 3D reformatted images confirmed the results obtained by transverse and coronal CT studies. The CT density of the liver in HU was 195.6 ± 73.1. The CT and 3D reconstructed images were visualized at high resolution. This data could be used as a basis for further morphological and imaging studies.

In vivo biodistribution and ototoxicity assessment of cationic liposomal-ceftriaxone via noninvasive trans-tympanic delivery in chinchilla models: Implications for otitis media therapy.

OBJECTIVES: We report the in vivo biodistribution and ototoxicity of cationic liposomal-ceftriaxone (CFX) delivered via ear drop formulation in adult chinchilla. METHODS: CFX was encapsulated in liposomes with size of ∼100 nm and surface charge of +20 mV. 100 µl liposomes or free drug was applied twice daily in both external ear canals of adult chinchillas for either 3 or 10 days. Study groups included free ceftriaxone (CFX, Day 3: n = 4, Day 10: n = 8), liposomal ceftriaxone (CFX-Lipo, Day 3: n = 4, Day 10: n = 8), and a systemic control group (Day 3: n = 4, Day 10: n = 4). Ceftriaxone delivery to the middle ear and systemic circulation was quantified by HPLC assays. Liposome transport was visualized via confocal microscopy. Auditory brainstem response (ABR) tests and cochlear histology were used to assess ototoxicity. RESULTS: Liposomal ceftriaxone (CFX-Lipo) displayed a ∼658-fold increase in drug delivery efficiency in the middle ear relative to the free CFX (8.548 ± 0.4638% vs. 0.013 ± 0.0009%, %Injected dose, Mean ± SEM). CFX measured in blood serum (48.2 ± 7.78 ng/ml) following CFX-Lipo treatment in ear was 41-fold lower compared to systemic free-CFX treatment (1990.7 ± 617.34 ng/ml). ABR tests and histological analysis indicated no ototoxicity due to the treatment. CONCLUSION: Cationic liposomal encapsulation results in potent drug delivery across the tympanic membrane to the middle ear with minimal systemic exposure and no ototoxicity.

High Prevalence of Hymenolepis (Rodentolepis) nana in Amateur Breeding Facilities of Chinchillas (Chinchilla lanigera) and Sugar Gliders (Petaurus breviceps) from Italy.

PURPOSE: Hymenolepis (Rodentolepis) nana is an enteric tapeworm globally widespread in wild and captive rodents. The survey was carried out in three chinchilla breeding facilities and in one sugar glider breeding facility in Central and Southern Italy. METHODS: One hundred and four chinchilla fecal pools and 40 sugar glider fecal pools were collected from cages housing breeding pairs or females with their offspring. Fecal samples were examined with a qualitative and quantitative copromicroscopical approach. Hymenolepis eggs were identified based on morphological and morphometrical features, and the average number of eggs per gram (EPG) of feces was estimated. RESULTS: Hymenolepis nana eggs were detected in 39.42% of chinchilla samples with an average of 16.33 EPG; whereas, all of the sugar glider samples tested positive with an average of 454.18 EPG. Neither helminth eggs nor protozoan cysts/oocysts were detected in any of the breeding facilities. CONCLUSION: The results clearly show a diffuse parasitism in both chinchillas and sugar gliders, and should be taken into consideration given the rising popularity of these two pet species combined with the zoonotic complications presented by H. nana.

Phacoemulsification in a chinchilla (Chinchilla lanigera).

Background: A cataract is one of the underlying causes of blindness in animals. Phacoemulsification is the standard procedure in cataract surgery for humans and animals. This procedure has been used to restore vision in cataracts in a variety of animals. However, this technique is difficult in very small animals, such as rodents, due to their small eyes. Case Description: A 4-year-old male domestic chinchilla was presented with cloudiness in the lenses for 1 month. The ophthalmic examination revealed cataracts (oculus uterque: both eyes). Positive dazzle reflex oculus sinister; left eye (OS) and negative reflex oculus dexter; right eye (OD) were noted. The electroretinography was low amplitude OS whereas a flat waveform presented OD. In this case, cataract surgery was performed using phacoemulsification without intraocular lens implantation OS. Postoperative, the chinchilla was alert and could jump on and jump off the ledge in a house. When the veterinarian approached closely to OS, the chinchilla displayed an erect body posture and open eyes, whereas the chinchilla was ignored when the veterinarian doing the same OD. The chinchilla was alert and had improved vision observe by this chinchilla can jump on and jump off the ledge in his house throughout the follow-up period 18 months later. Conclusion: In this chinchilla, phacoemulsification was successfully performed and resulted in better overall vision. The chinchilla was alert and could jump on and jump off the ledge in a house after cataract surgery throughout the follow-up period of 18 months.

Binocular 3-D otolith-ocular reflexes: responses of chinchillas to natural and prosthetic stimulation after ototoxic injury and vestibular implantation.

The otolith end organs inform the brain about gravitational and linear accelerations, driving the otolith-ocular reflex (OOR) to stabilize the eyes during translational motion (e.g., moving forward without rotating) and head tilt with respect to gravity. We previously characterized OOR responses of normal chinchillas to whole body tilt and translation and to prosthetic electrical stimulation targeting the utricle and saccule via electrodes implanted in otherwise normal ears. Here we extend that work to examine OOR responses to tilt and translation stimuli after unilateral intratympanic gentamicin injection and to natural/mechanical and prosthetic/electrical stimulation delivered separately or in combination to animals with bilateral vestibular hypofunction after right ear intratympanic gentamicin injection followed by surgical disruption of the left labyrinth at the time of electrode implantation. Unilateral intratympanic gentamicin injection decreased natural OOR response magnitude to about half of normal, without markedly changing OOR response direction or symmetry. Subsequent surgical disruption of the contralateral labyrinth at the time of electrode implantation surgery further decreased OOR magnitude during natural stimulation, consistent with bimodal-bilateral otolith end organ hypofunction (ototoxic on the right ear, surgical on the left ear). Delivery of pulse frequency- or pulse amplitude-modulated prosthetic/electrical stimulation targeting the left utricle and saccule in phase with whole body tilt and translation motion stimuli yielded responses closer to normal than the deficient OOR responses of those same animals in response to head tilt and translation alone.NEW & NOTEWORTHY Previous studies to expand the scope of prosthetic stimulation of the otolith end organs showed that selective stimulation of the utricle and saccule is possible. This article further defines those possibilities by characterizing a diseased animal model and subsequently studying its responses to electrical stimulation alone and in combination with mechanical motion. We show that we can partially restore responses to tilt and translation in animals with unilateral gentamicin ototoxic injury and contralateral surgical disruption.

Clinical, pathologic, and immunohistochemical features of pituitary tumors in 4 chinchillas.

Pituitary tumors are rare in chinchillas. This report describes the clinical, gross, histologic, and immunohistochemical characteristics of pituitary tumors in 4 chinchillas. The affected chinchillas were females between 4 and 18 years of age. Clinically, neurologic signs were most commonly reported and included depression, obtundation, seizure, head-pressing, ataxia, and possible blindness. Computed tomography scanning of 2 chinchillas revealed solitary intracranial extra-axial masses in the region of the pituitary gland. Two pituitary tumors were confined to the pars distalis; the other 2 invaded the brain. Based on their microscopic appearances and lack of distant metastases, all 4 tumors were diagnosed as pituitary adenomas. Immunohistochemically, all pituitary adenomas were weakly to strongly positive for growth hormone, most consistent with the diagnosis of somatotropic pituitary adenomas. To the authors' knowledge, this is the first detailed report of the clinical, pathologic, and immunohistochemical features of pituitary tumors in chinchillas.

Epistatic Effects Between Amino Acid Insertions and Substitutions Mediate Toxin resistance of Vertebrate Na+,K+-ATPases.

The recurrent evolution of resistance to cardiotonic steroids (CTS) across diverse animals most frequently involves convergent amino acid substitutions in the H1-H2 extracellular loop of Na+,K+-ATPase (NKA). Previous work revealed that hystricognath rodents (e.g., chinchilla) and pterocliform birds (sandgrouse) have convergently evolved amino acid insertions in the H1-H2 loop, but their functional significance was not known. Using protein engineering, we show that these insertions have distinct effects on CTS resistance in homologs of each of the two species that strongly depend on intramolecular interactions with other residues. Removing the insertion in the chinchilla NKA unexpectedly increases CTS resistance and decreases NKA activity. In the sandgrouse NKA, the amino acid insertion and substitution Q111R both contribute to an augmented CTS resistance without compromising ATPase activity levels. Molecular docking simulations provide additional insight into the biophysical mechanisms responsible for the context-specific mutational effects on CTS insensitivity of the enzyme. Our results highlight the diversity of genetic substrates that underlie CTS insensitivity in vertebrate NKA and reveal how amino acid insertions can alter the phenotypic effects of point mutations at key sites in the same protein domain.

No Reduction in the 226-Hz Probe Tone Acoustic Reflex Amplitude Following Severe Inner Hair Cell Loss in Chinchillas.

The relationship between the middle ear acoustic reflex (AR) and inner hair cell (IHC) loss is currently unknown. Given that IHC are believed to convey nearly all acoustic information to the central auditory nervous system, it has been assumed that loss of IHC would significantly impact the AR. To evaluate this relationship, we assessed the presence and amplitude of the AR in chinchillas before and after treatment with carboplatin, an anticancer drug that reliably and selectively destroys IHC in this species. Baseline measures of hearing sensitivity, including auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAE), were assessed and then re-evaluated following carboplatin treatment. Post-carboplatin ABR thresholds and DPOAE were found to be unchanged or slightly elevated; results were consistent with published reports. Our main hypothesis was that loss of IHC would abolish the reflex or significantly reduce its amplitude. Contrary to our hypothesis, the ipsilateral 226-Hz AR continued to be reliably elicited following carboplatin treatment. Post-mortem histological analysis confirmed significant IHC loss (65-85 %), but no measurable loss of outer hair cells (OHCs). Given that loss of IHC alone does not significantly reduce the 226-Hz AR, our results suggest that few IHC are needed to maintain the 226-Hz AR response. These results suggest additional studies are needed to better understand the role of IHC in the reflex arc, present opportunities to further study the reflex pathway, and could change how we use the clinical AR as a potential diagnostic tool for IHC dysfunction, including those related to IHC synaptopathy.

Pathology of Salmonella enterica Subspecies enterica Serotype Typhimurium Infection in Chinchillas (Chinchilla lanigera).

Septicaemia is the main pathological manifestation of Salmonella infection in chinchillas (Chinchilla lanigera), although information on its pathology is limited. We now describe the gross, histological and immunohistochemical features of Salmonella enterica subspecies enterica serotype Typhimurium (S. Typhimurium) infection in ranched chinchillas. Eighty-five adult pregnant chinchillas had anorexia, prostration, weight loss, hyperthermia and abortion. Necropsy of 13 animals revealed splenomegaly, hepatomegaly, mesenteric lymphadenomegaly, prominent Peyer's patches, pulmonary oedema, white pinpoint lesions in multiple organs and petechiae in the urinary bladder. In all cases, histological lesions were consistent with septicaemia, characterized by acute necrotizing hepatitis, splenitis, lymphadenitis, cystitis, pneumonia, enterocolitis, gastritis and/or nephritis. Immunohistochemistry for Salmonella spp on seven cases revealed intralesional immunolabelling in all affected organs. Salmonella sp was isolated from liver, spleen, intestinal contents and blood of 10 chinchillas. Isolates of four animals were identified as S. Typhimurium.

Clinicopathologic, immunohistochemical, and ultrastructural features of histiocytic sarcoma in a chinchilla (Chinchilla lanigera).

A 9-year-old intact female chinchilla (Chinchilla lanigera) was presented to a referring veterinarian due to small, multiple cervical nodules that had been rapidly increasing in size and number. Cytology of the nodules revealed sheets of pleomorphic round cells that were morphologically most compatible with histiocytic sarcoma. Histologically, the nodules were fairly demarcated, partially infiltrative, densely cellular neoplasm, and was composed of pleomorphic large round cells arranged in sheets. Special stains for bacteria (Gram stain and Ziehl-Neelsen stain) and fungi (periodic acid-Schiff stain) were all negative. On immunohistochemistry, the neoplastic cells showed strong cytoplasmic positivity for Iba-1 and CD204, but were negative for CD3 and CD20. Transmission electron microscopy failed to detect Birbeck's granules in the cytoplasm of the neoplastic histiocytes. The chinchilla received chemotherapy with lomustine but died spontaneously on day 62 despite treatment. Autopsy with histopathologic examination revealed disseminated histiocytic sarcoma involving the bone marrow, bronchial lymph nodes, nasal cavity, lung, heart, stomach, pancreas, pancreatic lymph nodes, liver, spleen, and kidney. To the best of our knowledge, this is the first report of disseminated histiocytic sarcoma in chinchillas.

Concomitant Congenital Diaphagmatic Hernia (CDH) and bilateral bacterial glomerulonephritis in a pet chinchilla (Chinchilla lanigera).

BACKGROUND: The domestic chinchilla has been descended from Chinchilla lanigera (long-tailed Chinchilla) or Chinchilla chinchilla (short-tailed Chinchilla). Both species of chinchilla are currently listed as endangered by the IUCN Red List of Threatened Species. Over the past 20 years, they have spread as pets and overall knowledge about their care is improving. The present case report describes a congenital diaphragmatic hernia in a Chinchilla lanigera. CASE PRESENTATION: A 1-year-old, 420 g female chinchilla (Chinchilla lanigera) was presented for clinical examination due to 2 days haematuria episodes and anorexia. A complete haematological analysis was performed, showing a moderate neutrophilia and severe renal involvement. X-rays showed severe intestinal meteorism affecting mostly the cecum, and a soft tissue density mass with translucent areas located in the caudal thorax, making it hard to distinguish the cardiac silhouette. A barium swallow (barium sulfate) was performed and after 20 min, radiograms were performed again, showing part of the stomach dislocated in thorax. Ultrasound was also carried out, confirming the partial stomach herniation into the thoracic cavity and a severe nephropathy. The patient was euthanized according to the owner's wish and a complete necropsy was performed. The diagnosis was congenital diaphragmatic hernia concomitant to a severe bilateral bacterial glomerulonephritis. DISCUSSION AND CONCLUSIONS: Diaphragmatic hernias can be either congenital or acquired. About CDHs in pet chinchillas, literature is still lacking. In this patient there was no history of previous traumas. No scar tissue or thickening involved margins of the pathological diaphragm window at the necropsy, supporting the hypothesis of a congenital defect. Glomerulonephritis most often results from immune-mediated mechanisms, generally after the deposition of soluble immune complexes within the glomeruli. This mechanism is favoured by a prolonged antigenemia that could occur during specific viral infections, chronic bacterial infections, chronic parasitism, autoimmune diseases and neoplasia. Few cases of nephritis are described in chinchillas (Chinchilla lanigera), mostly related to bacterial sepsis or less commonly involving fungi. The evidence of bacterial aggregates in kidneys at the histopathology, confirmed the infective aetiology. No relationship between the diaphragmatic hernia and glomerulonephritis was found in this report.

Genotoxicity of physical silver nanoparticles, produced by the HVAD method, for Chinchilla lanigera genome.

Each year, growing demand for silver nanoparticles (AgNP) contributes to the search for alternative methods of their production. Stable AgNP with antibacterial properties, low toxicity to the environment and living organisms are especially valued. In the study presented here, an attempt was made to assess the toxicity of two AgNP solutions produced using the HVAD method to the Chinchilla lanigera genome. The AgNO3 solution was the indicator and reference for the harmfulness of AgNP. The study was carried out in vitro on bone marrow cells isolated from Chinchilla lanigera bones. The genotoxicity was assessed by comet assay, following the treatment of cells with three silver solutions: unstable and sodium citrate-stabilized silver nanoparticles, as well as silver nitrate at three concentrations (5, 10 and 20 µg/L), after 3, 6 and 24 h. Based on the percentage of the DNA content in the comet tail and the tail moment, an increase in cell DNA integrity disruption was demonstrated in all tested variants: of solution, exposure time and concentration, compared to the control sample. A statistically significant correlation was determined between the level of induced DNA breaks and the concentration of the active solutions and the duration of their activity. A solution of silver nanoparticles stabilized with sodium citrate was shown to have the most harmful effect on bone marrow cells. Silver nitrate demonstrated a level of toxicity similar to these particles. Further studies are necessary to directly compare the genotoxic properties of AgNP produced using the HVAD method and the chemical method under the same conditions.

First report of deep crypt secretory cells in ascending colon in chinchilla (Chinchilla lanigera): a histological and histochemical study / Primer reporte de células secretoras de criptas profundas en colon ascendente en chinchilla (Chinchilla lanigera): un estudio histológico e histoquímico

SUMMARY: The normal morphology of the colon differs among mammal species.The ascending colon presents several types of cells, responsible for carrying different functions for this organ. Among them, the mucus-secreting cells ensure the integrity of the mucosa, local defense, protection against different external factors, inflammatory diseases, cancer, etc. The ascending colon from 5 adult male chinchillas were processed for paraffin embedding and stained with three methods: Goldner's trichrome, PAS reaction, and Alcian blue staining procedure. The results showed that the structure of the ascending colon is similar to the one described in other species, i.e. mucosa, submucosa, muscularis externa, and serosa. Regarding the mucus-secreting cells present in the deeper part of the mucosal crypts (deep crypt secretory or DCS cells) turned out to be different not only morphologically from the surface goblet cells but also regarding the type of mucus synthesized. DCS cells have a multivacuolated, faintly stained cytoplasm with moderately PAS-positive reaction and intensely positive reaction to Alcian blue stain. The mean surface of DCS cells was 521.6 μm2 as compared to 437.9 μm2 for goblet cells (p<0.05). In conclusion, our study describes for the first time in chinchilla (Chinchilla lanigera) the presence of formerly known non-goblet or vacuolated cells, and recently entitled DCS cells in the glandular epithelium of the colon. The understanding of morphological peculiarities in chinchilla may serve as a good basis to understand the pathophysiology of various conditions that may arise.

RESUMEN: La morfología normal del colon es diferente entre las especies de mamíferos. El colon ascendente presenta varios tipos de células, encargadas de llevar varias funciones a este órgano. Entre ellos, las células secretoras aseguran la integridad de la mucosa, defensa local, protección frente a diferentes factores externos, enfermedades inflamatorias, cáncer, etc. Se procesaron para su inclusión en parafina el colon ascendente de 5 chinchillas machos adultos y se tiñeron con tres métodos: tricrómico de Goldner, reacción PAS y Azul de Alcian. Los resultados mostraron que la estructura de del colon ascendente es similar a la descrita en otras especies, es decir, mucosa, submucosa, muscular externa y serosa. Las células secretoras de la mucosa presente en la parte más profunda de las criptas mucosas (células secretoras de la cripta profunda o células DCS) resultaron ser diferentes morfológicamente de las células caliciformes superficiales, con citoplasma levemente teñido con reacción PAS positiva moderada y reacción intensamente positiva a Azul de Alcian. La superficie media de las células DCS fue de 521,6 μm2 en comparación con 437,9 μm2 de las células caliciformes (p <0,05). En conclusión, nuestro estudio describe por primera vez en chinchilla (Chinchilla lanigera) la presencia de células no caliciformes o vacuoladas anteriormente conocidas, y recientemente denominadas células DCS en el epitelio glandular del colon. La comprensión de las peculiaridades morfológicas de la chinchilla puede servir como una buena base para comprender la fisiopatología de las diversas afecciones.

High-density lipoprotein remodeling by phospholipid nanoparticles improves cholesterol efflux capacity and protects from atherosclerosis.

The efficiency of cholesterol efflux from cells promoted by high-density lipoproteins (HDLs) depends on HDL concentration and functional properties. The term "dysfunctional HDL" describes HDLs with impaired protective properties. Cholesterol efflux capacity (CEC) of HDL is reduced in patients with atherosclerosis, but the exact mechanisms underlying this impairment are not well characterized. Enriching HDLs with phospholipids (PLs) improves CEC. Herein, we assessed the potential of PL nanoparticles in improving HDL functionality. We lipidated HDL subfractions by incubating with PL nanoparticles containing soybean polyunsaturated phosphatidylcholine. Incubating blood plasma with PL nanoparticles resulted in the dose-dependent lipidation of all HDL subfractions. Changes in apolipoprotein A1 (apoA-1) and PL concentrations were the most prominent in the HDL2 fraction. Concentrations of PL in the HDL3 fraction and the fraction with a density > 1.21 g/mL increased by 30-50%, whereas apoA-1 levels decreased. We hypothesized that PL nanoparticles may cause HDL remodeling that can improve their functions. The CECs of lipidated HDLs were analyzed by incubating apolipoprotein B (apoB)-depleted plasma with 3H-cholesterol-labeled THP-1 macrophages. The findings revealed a two-fold increase in cholesterol efflux compared with native apoB-depleted plasma. Moreover, intravenous administration of PL nanoparticles restored lipid profiles and effectively protected blood vessels from atherosclerosis progression in cholesterol-fed rabbits compared with that of fenofibrate and atorvastatin. PL nanoparticles also protected against atherosclerosis and decreased the atherogenic index. Altogether, these results indicate that PL nanoparticles can be used to correct the lipid composition and CEC of HDLs. DATA AVAILABILITY: Additional data can be provided upon reasonable request from the date of publication of this article within 5 years. The request should be sent to the author-correspondent at the address cd95@mail.ru.

Ultrasonic bone removal from the ossicular chain affects cochlear structure and function.

INTRODUCTION: Ultrasonic bone removal devices (UBD) are capable of cutting through bony tissue without injury to adjacent soft tissue. The feasibility and safety of using this technology for removal of bone from an intact ossicular chain (as might be required for otosclerosis or congenital fixation) was investigated in an animal model. METHODS: This was a prospective animal study conducted on seven anesthetised adult chinchillas. An UBD was used to remove bone from the malleus head in situ. Pre and post-operative distortion product otoacoustic emission (DPOAE) levels and auditory brainstem response (ABR) thresholds were recorded. Scanning electron microscopy (SEM) was used to assess cochlear haircell integrity. RESULTS: Precise removal of a small quantity of bone from the malleus head was achieved by a 30s application of UBD without disruption of the ossicular chain or tympanic membrane. DPOAEs became undetectable after the intervention with signal-to-noise ratios (SNR) < 5 dB SPL in all ears. Furthermore, ABR thresholds were elevated > 85 dB SPL in 13 ears. SEM showed significant disruption of structural integrity of the organ of Corti, specifically loss and damage of outer haircells. CONCLUSIONS: Although UBD can be used to reshape an ossicle without middle ear injury, prolonged contact with the ossicular chain can cause structural and functional injury to the cochlea. Extensive cochlea pathology was found, but we did not investigate for recovery from any temporary threshold shift. In the authors' opinion, further study should be undertaken before consideration is given to use of the device for release of ossicular fixation.

[Inner hair cells loss by carboplatin and the changes of cochlear compound action potential in chinchillas].

Objective: To measure the cochlear compound action potential (CAP) and the densities of hair cells (HCs) along the whole length of the basilar membrane (BM) in adult chinchillas. And to investigate the relationship between the severity of inner hair cells (IHCs) loss and the changes of CAP by using carboplatin-cochlear lesion model. Methods: Totally 18 chinchillas were recruited after ontological evaluation. They were randomly divided into three groups (with 6 subjects in each), A: control, B and C: legion groups treated with one or two shot(s) of carboplatin respectively (76 mg/kg in one shot, i.p., one-week interval between the two shots). Endpoint tests were performed 30 days after the carboplatin treatment in groups B and C, and matched time in group A. A sliver-ball electrode was placed into round window niche via hypotympanic approach in anesthetized chinchilla. CAP was measured in response to clicks and tone burst of 0.5, 1, 2, 4, 8, 16 kHz respectively under anesthesia. CAP amplitudes and thresholds were measured and compared across the groups. After the recording, the whole cochlea surface preparation was made and the HCs were stained in histochemistry against substrate of succinate dehydrogenase (SDH). Images were taken with high-resolution digital camera under light microscope and across the whole cochlea. The length of the basilar membrane (BM) and the number of both IHCs and OHCs were counted. The HC density was calculated as the number of HCs per 10% BM length. Results: The CAP thresholds were (7.1±2.6), (25.4±5.0), (24.6±5.4), (10.4±5.0), (0.4±1.4), (4.2±6.3) and (17.1±14.1) dB SPL (from 6 subjects in group A, n=12 ears) corresponding to stimuli of Click and 0.5, 1, 2, 4, 8, 16 kHz tone bursts respectively. The total number of cochlear HCs were measured as (8 936±643) (x±s) and the average length of the BMs was (17.73±1.012) mm from the six subjects in the group A (n=12 ears). The HC density was found to be varied slightly across the BM. There was no significant CAP threshold difference between the control (group A) and the group B, which received one shot of carboplatin. However, the maximal CAP amplitude was reduced by 40% in the group B and compared with group A. Correspondingly, approximately 40% loss of IHCs were seen. In contrast, a significant CAP threshold shift was seen in subjects receiving two shots of carboplatin (group C), which was accompanied by a loss of 90% IHCs. Conclusions: The CAP thresholds of adult chinchillas show typical open-V shape with the lowest values at 2, 4, and 8 kHz. IHC loss by carboplatin in certain degree is well correlated with CAP amplitude reduction, but does not change the threshold when inner hair cell loss reaches 40%, however, if inner hair cell loss exceeds 80%, the threshold shift of CAP will be inevitable.

Gap Detection Deficits in Chinchillas with Selective Carboplatin-Induced Inner Hair Cell Loss.

Temporal resolution is essential for processing complex auditory information such as speech. In hearing impaired persons, temporal resolution, often assessed by detection of brief gaps in continuous sound stimuli, is typically poorer than in individuals with normal hearing. At low stimulus presentation levels, hearing impaired individuals perform poorly but the deficits are greatly reduced when the sensation level of the stimuli are adjusted to match their normal hearing peers. In the present study, we evaluated the effect of selective inner hair cell loss on gap detection in chinchillas treated with carboplatin, an anticancer drug that selectively damages inner hair cells and afferents in this species. Treatment with carboplatin-induced inner hair cell loss of ~ 70 % but had little effect on audiometric thresholds in quiet and produced no evidence of outer hair cell loss. In contrast, selective inner hair cell loss had a significant effect on gap detection ability across a wide range of presentation levels. These results suggest that gap detection tasks are more sensitive to inner hair cell pathology than audiometric thresholds.

Prevalencia y hallazgos radiográficos en conejos, cuyos y chinchillas diagnosticados con maloclusión en el Hospital Veterinario de Especialidades en Fauna Silvestre y Etología Clínica de la UNAM, México / Prevalence and radiographic findings in rabbits, guinea pigs and chinchillas diagnosed with malocclusion at the UNAM Exotic Pet and Wildlife Teaching Hospital, Mexico

RESUMEN Los lagomorfos y los histricomorfos, como los cuyos y las chinchillas, comparten características dentales como: dentadura elodonta e hipsodonta. Estas peculiaridades predisponen la presentación de maloclusión debido al consumo de dietas inadecuadas, poco abrasivas. El propósito de este trabajo es identificar la prevalencia de maloclusión en cada una de las especies mencionadas, de acuerdo con su sexo y grupo etario. Además, tiene como objetivo hacer una evaluación objetiva de los estudios radiográficos de los ejemplares, basada en líneas de referencia anatómica, para determinar los principales hallazgos radiográficos según el grado de maloclusión diagnosticado de forma clínica. El 30% de todos los individuos evaluados presentaron problemas de maloclusión, 42,86% de ellos conejos, 16,6% cuyos y 23% chinchillas. No se evidenciaron diferencias significativas en la presentación por sexo. En conejos fue más común el diagnóstico de ejemplares del grupo etario I y II, mientras que en cuyos lo fue en los grupos II y III. El grado I y II fueron los más diagnosticados en conejos y cuyos. En las radiografías las lesiones más comunes fueron el sobrecrecimiento de las raíces maxilares y mandibulares, elongación de incisivos, pérdida de la superficie de oclusión y deformación de las raíces mandibulares. Se propone un método de corrección para las proyecciones radiográficas LL con rotación evidente para mantener la objetividad de la evaluación radiográfica.

ABSTRACT Lagomorphs and histricomorphs, as guinea pigs and chinchillas, have common dental characteristics, such as the elodont and hypsodont teeth. These peculiarities predispose to the presentation of malocclusion due to the consumption of inadequate, non-abrasive diets. The purpose of this work is to identify the prevalence of malocclusion in each case. In addition, it aims to make an objective evaluation of the radiological studies of the specimens, based on anatomical reference lines, to determine the main radiographic findings according to the degree of malocclusion clinically diagnosed. 30% of the individuals evaluated presented malocclusion problems being 42.86% rabbits, 16.6% guinea pigs and 23% chinchillas. There is no evidence of significant differences in the presentation by sex. In rabbits, the diagnosis of the specimens from the group I and II were more common, while in guinea pigs they were II and Ill. Grade I and II were the most diagnosed in rabbits and guinea pigs. In the radiographs, the most common lesions are the overgrowth of the maxillary and mandibular roots, elongation of the incisors, loss of the occlusal surface and deformation of the mandibular roots. A method of correction for LL radiographic projections with evident rotation is proposed to maintain the objectivity of the radiographic evaluation.