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Abstract To compare the vibrational patterns of human and guinea pig cochleae accurately, we developed and validated a novel finite element model of the guinea pig, leveraging it to analyze vibrational patterns in the cochlea. This approach is mirrored in our examination of the human cochlear model, providing granular insights into the nuances of human bone conduction hearing. The comparative analysis reveals that the guinea pig cochlea mirrors human cochlear vibrational patterns, thus serving as an efficient proxy for exploring human cochlear function. The human mastoid and the upper region of the guinea pig’s skull are recommended as the convenient and comparable sites for bone conduction stimulation. The cochlear vibration pattern encompasses a mix of rigid, rotational, and compressive motion. Significantly, the guinea pig model demonstrates robust agreement with existing experimental data and other studies, these findings are confirming the validity of the model. Our study delineates the distinct roles of the three vibration types across various frequency spectrums. At lower frequencies, rigid motion is the dominant mechanism, supplemented by rotational motion. However, at higher frequencies, the influence of rigid motion wanes, ceding prominence to rotational and compressive motions. This trend is consistently observed in both human and guinea pig models.

Abstract Trixacarus caviae is a sarcoptic mange mite infesting guinea pigs. Infestation in immunosuppressed animals produces severe dermatological problems, including alopecia, intense pruritus, hyperkeratosis and non‐dermatological issues (e.g., seizures). Treatment options are limited and include topical application of macrocyclic lactones or amitraz or injectable administration of ivermectin or doramectin. Considering the severity of the disease and the challenging treatment, the present paper aimed to determine the efficacy of oral afoxolaner in a severe case of infestation with T. caviae in a pet guinea pig. One female guinea pig was referred to the New Companion Animal Clinic due to severe dermatological problems. A clinical evaluation was done, and skin scrapings were collected and examined under the microscope. Small mites were detected and morphologically identified as T. caviae. The animal was treated with a single oral dose of 2.50 mg/kg afoxolaner, and the lesions, presence/absence of mites and intensity of pruritus were evaluated periodically until 2 months post‐treatment. A week after the medication, the lesions were milder, but pruritus was still present and was attributed to the healing process. Further examinations showed significant improvement with the complete remission of clinical signs and no mites at the microscopic examination after 4 weeks. Afoxolaner was safe and effective in this guinea pig for the treatment of T. caviae mange with no repetition needed.

Masticatory myositis is an autoimmune neuromuscular disorder that affects the muscles of mastication. The affected individual has difficulties in opening or closing the mouth, pain, and swelling in the acute phase, and significant atrophy of the affected musculature in the chronic phase. A guinea pig (Cavia porcellus) with a history of chronic hyporexia, recurrent cheek teeth overgrowth, and loss of facial silhouette, was suspected of having masticatory myositis. The disease was confirmed by computed tomography and histopathological examination of muscle fragments. The patient was treated with a protocol involving corticosteroids and gabapentin, and occlusal correction procedures. [ABSTRACT FROM AUTHOR]

AIM: To quantitatively measure ocular morphological parameters of guinea pig with Python technology. METHODS: Thirty-six eyeballs of eighteen 3-week-old guinea pigs were measured with keratometer and photographed to obtain the horizontal, coronal, and sagittal planes respectively. The corresponding photo pixels-actual length ratio was acquired by a proportional scale. The edge coordinates were identified artificially by ginput function. Circle and conic curve fitting were applied to fit the contour of the eyeball in the sagittal, coronal and horizontal view. The curvature, curvature radius, eccentricity, tilt angle, corneal diameter, and binocular separation angle were calculated according to the geometric principles. Next, the eyeballs were removed, canny edge detection was applied to identify the contour of eyeball in vitro. The results were compared between in vivo and in vitro. RESULTS: Regarding the corneal curvature and curvature radius on the horizontal and sagittal planes, no significant differences were observed among results in vivo, in vitro, and the keratometer. The horizontal and vertical binocular separation angles were 130.6°±6.39° and 129.8°±9.58° respectively. For the corneal curvature radius and eccentricity in vivo, significant differences were observed between horizontal and vertical planes. CONCLUSION: The Graphical interface window of Python makes up the deficiency of edge detection, which requires too much definition in Matlab. There are significant differences between guinea pig and human beings, such as exotropic eye position, oblique oval eyeball, and obvious discrepancy of binoculus. This study helps evaluate objectively the ocular morphological parameters of small experimental animals in emmetropization research.

AIM: To avoid the problem of retinal dissection in guinea pig large eyeball tissue sections, different methods were used to optimize the fixation effect of the posterior pole of the eyeball.METHODS: A total of 75 normal guinea pigs(2 weeks old)were randomly divided into 5 large groups. Group A(1-3 small groups), the entire eyeball was fixed with FAS, Davidson fixative 1(D1), and Davidson fixative 2(D2)for 24 h; group B(4-6 small groups), the entire eyeball was fixed with FAS, D1, and D2 for 1 h, then cut the cornea and fix it in their respective fixatives for 2 h; group C(7-9 small groups), the eyeball was fixed in FAS, D1, and D2 for 1 h, divided into left and right halves along the direction of the optic nerve, and then placed them in their respective fixation solutions for 2 h; group D(10-12 small groups), after fixation for 3 h in FAS, D1, and D2, the eyeball was divided into left and right halves along the optic nerve direction; group E(13-15 small groups), the cornea was cut after fixation for 3 h in FAS, D1, and D2. Hematoxylin-eosin(HE)staining was used to compare the fixation effect on posterior eyeball in each group.RESULTS: After fixation, the surface of the eyeballs in groups, 1-6 and 11-15 was smooth and round, with a transparent and bright color. In groups 7-10, the eyeballs were sunken, wrinkled, and deformed. The HE staining showed that the eyeball morphology of groups 1, 5, 6, 14, and 15 was significantly better than the other groups, with a regular internal tissue structure. The eyeballs of the other groups were sunken and wrinkled, and the internal tissue was curled and tangled, with severe retinal detachment. In groups 1, 5, 6, 14, and 15, the retina, choroid, and sclera tissues of group 14 were closely connected, without obvious retinal detachment, rupture, or curling. The tissue structure was clear and visible, and the cells were arranged neatly.CONCLUSION: The fixation effect of cutting the cornea after fixing guinea pig eyeball with D1 fixative for 3 h is the most ideal, and this operation method is simple and suitable for studying the related structures of the posterior pole of the eye.

PURPOSE: We previously reported differential gene expression of the bone morphogenetic protein 2 (Bmp2) in guinea pig retinal pigment epithelium (RPE) after 1 day of hyperopic defocus, imposed with a negative contact lens (CLs). The study reported here sought to obtain insights into the temporal profiles of gene expression changes in Bmp2, as well as those of two closely related genes, the inhibitor of DNA binding 3 (Id3) and Noggin (Nog), both during myopia induction and when the CL treatment was terminated to allow recovery from induced myopia. METHODS: To induce myopia, 2-week-old pigmented guinea pigs (New Zealand strain, n = 8) wore monocular -10 diopter (D) rigid gas-permeable (RGP) CLs for one week, while the other eye served as a control. Ocular measurements were made at baseline, 3 days, and 7 days after the initiation of CL wear, with treatment then being terminated and additional measurements being made after a further 3 days, 1 week, and 2 weeks. Spherical equivalent refractive errors (SERs), axial length (AL), choroidal thickness (ChT), and scleral thickness (ScT) data were collected using retinoscopy, optical biometry (Lenstar), and spectral domain optical coherence tomography (SD-OCT), respectively. RPE samples were collected from both eyes of the guinea pigs after either 1 day or 1 week of CL wear or 1 day or 2 weeks after its termination, and RNA was subsequently isolated and subjected to quantitative real-time PCR (qRT-PCR) analyses, targeting the Bmp2, Id3, and Nog genes. RESULTS: Mean interocular differences (treated-control) in AL and SER were significantly different from baseline after 3 and 7 days of CL wear, consistent with induced myopia (p < 0.001 for all cases). Termination of CL wear resulted in the normalization (i.e., recovery) of the ALs and SERs of the treated eyes within 7 days, and the earlier significant ChT thinning with CL wear (p = 0004, day 7) was replaced by rapid thickening, which remained significant on day 7 (p = 0.009) but had normalized by day 14. The ChT changes were much smaller in magnitude than the AL changes in both phases. Interocular differences in the ScT showed no significant changes. The Bmp2 and Id3 genes were both significantly downregulated with CL wear, after 1 day (p = 0.012 and 0.016) and 7 days (p = 0.002 and 0.005), while Bmp2 gene expression increased and Nog gene expression decreased after the termination of CL wear, albeit transiently, which was significant on 1 day (p = 0.004 and 0.04) but not 2 weeks later. No change in Id3 gene expression was observed over the latter period. Conclusions: The above patterns of myopia induction and recovery validate this negative RGP-CL model as an alternative to traditional spectacle lens models for guinea pigs. The defocus-driven, sign-dependent changes in the expression of the Bmp2 gene in guinea pig RPE are consistent with observations in chicks and demonstrate the important role of BMP2 in eye growth regulation.

This review explores the economic impact and importance of guinea pig production for sustainable food security and sovereignty in South America. The ease of management, short reproductive cycles of 16 days, and profitability make guinea pig farming attractive. The review delves into the diverse breeds, breeding systems, and facilities employed, emphasizing the crucial role of guinea pigs in South American economies. Descriptions of the guinea pig’s physical attributes, origin, and digestive system underscore their adaptability and versatility. The review also details feeding practices, nutritional requirements, and alternative strategies to enhance feed efficiency, addressing the importance of vitamin C supplementation. Probiotic strains’ incorporation into guinea pig diets is explored for improved health and productivity. Furthermore, the manuscript discusses slaughter methods and concludes by emphasizing the role of guinea pig breeding in sustainable food security and sovereignty, highlighting challenges, and advocating for responsible antibiotic use to mitigate potential risks of antimicrobial resistance.

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus and the leading cause of infectious disease related birth defects worldwide. How the immune response modulates the risk of intrauterine transmission of HCMV after maternal infection remains poorly understood. Maternal T cells likely play a critical role in preventing infection at the maternal-fetal interface and limiting spread across the placenta, but concerns exist that immune responses to infection may also cause placental dysfunction and adverse pregnancy outcomes. This study investigated the role of CD4+ and CD8+ T cells in a guinea pig model of primary cytomegalovirus infection. Monoclonal antibodies specific to guinea pig CD4 and CD8 were used to deplete T cells in non-pregnant and in pregnant guinea pigs after mid-gestation. CD4+ T cell depletion increased the severity of illness, caused significantly elevated viral loads, and increased the rate of congenital guinea pig cytomegalovirus (GPCMV) infection relative to animals treated with control antibody. CD8+ T cell depletion was comparably well tolerated and did not significantly affect the weight of infected guinea pigs or viral loads in their blood or tissue. However, significantly more viral genomes and transcripts were detected in the placenta and decidua of CD8+ T cell depleted dams post-infection. This study corroborates earlier findings made in nonhuman primates that maternal CD4+ T cells play a critical role in limiting the severity of primary CMV infection during pregnancy while also revealing that other innate and adaptive immune responses can compensate for an absent CD8+ T cell response in α-CD8-treated guinea pigs.

In the present study, a total number of 10 guinea pig eyes were studied macroscopically and microscopically (with staining by H&E, Verhoeff, Van Gieson, and P.A.S.). The results showed that posterior surface of lens was more convex than anterior surface. The average lens diameter and thickness were respectively measured as 0.61±0.02 and 0.45±0.024 centimeters. The average ciliary body thickness was measured as 0.25±0.03 centimeters. In addition, the ciliary body’s mean external diameter as 0.92±0.03 centimeters and the number of ciliary body process is about 68. The epithelium of lens was cuboid and the lens capsule as positive PAS reaction intensively. The anterior surface of capsule was thicker than posterior one. The lens fibers in the central part were thicker than other parts and the elastic fibers in lens were not observed. The epithelium of ciliary processes has two layers; the superficial layer was non-pigmented and culumnar with eosinophilic cytoplasm. Deep layer of epithelium was non-pigmented and cuboid with clear cytoplasm. There was not any pigments in subepithelial tissue. The subciliary process’s connective tissue had smooth muscle with longitudinal sections. There are a lot of thick elastic fibers in the ciliary body tissue. In conclusion, the major distinction of guinea pig in addition to differences of the lens and ciliary body’s dimensions was lack of pigmentation of epithelial cells of ciliary body.

Primary cell culture is a technique that is widely used in neuroscience research to investigate mechanisms that underlie pathologies at a cellular level. Typically, mouse or rat tissue is used for this process; however, altricial rodent species have markedly different neurodevelopmental trajectories comparatively to humans. The use of guinea pig brain tissue presents a novel aspect to this routinely used cell culture method whilst also allowing for dual isolation of two major cell types from a physiologically relevant animal model for studying perinatal neurodevelopment. Primary neuronal and oligodendrocyte cell cultures were derived from fetal guinea pig's frontal cortex brain tissue collected at a gestational age of 62 days (GA62), which is a key time in the neuronal and oligodendrocyte development. The major advantage of this protocol is the ability to acquire both neuronal and oligodendrocyte cellular cultures from the frontal cortex of one fetal brain. Briefly, neuronal cells were grown in 12-well plates initially in a 24-h serum-rich medium to enhance neuronal survival before switching to a serum-free media formulation. Oligodendrocytes were first grown in cell culture flasks using a serum-rich medium that enabled the growth of oligodendrocyte progenitor cells (OPCs) on an astrocyte bed. Following confluency, the shake method of differential adhesion and separation was utilized via horizontally shaking the OPCs off the astrocyte bed overnight. Therefore, OPCs were plated in 12-well plates and were initially expanded in media supplemented with growth hormones, before switching to maturation media to progress the lineage to a mature phenotype. Reverse transcription-polymerase chain reaction (RT-PCR) was performed on both cell culture types to analyze key population markers, and the results were further validated using immunocytochemistry. Primary neurons displayed the mRNA expression of multiple neuronal markers, including those specific to GABAergic populations. These cells also positively stained for microtubule-associated protein 2 (MAP2; a dendritic marker specific to neurons) and NeuN (a marker of neuronal cell bodies). Primary oligodendrocytes expressed all investigated markers of the oligodendrocyte lineage, with a majority of the cells displaying an immature oligodendrocyte phenotype. This finding was further confirmed with positive oligodendrocyte transcription factor (OLIG2) staining, which serves as a marker for the overall oligodendrocyte population. This study demonstrates a novel method for isolating both neurons and oligodendrocytes from the guinea pig brain tissue. These isolated cells display key markers and gene expression that will allow for functional experiments to occur and may be particularly useful in studying neurodevelopmental conditions with perinatal origins.

Background: Segmental aplasia of the caudal vena cava with azygos continuation is a congenital malformation macroscopically described in mammals including humans, dogs and rodents. It is usually detected as an incidental finding and the final diagnosis is reached by computed tomography, fluoroscopy or post-mortem dissection. Case Description: A 3-year-old guinea pig (Cavia porcellus) presented with subacute dyspnea. A computed tomographic exam was performed for the evaluation of subtle pulmonary changes previously suspected on conventional radiography, and a segmental aplasia of the caudal vena cava with azygos continuation was identified as an incidental finding. Conclusion: According to database negative results, this is the first report describing a segmental aplasia of the caudal vena cava and azygos continuation in a guinea pig by computed tomography. [Open Vet J 2024; 14(4.000): 1076-1080]

This case report refers to a 1-year-old Guinea pig showing signs of anorexia and antipain posture. On abdominal radiography, five rounded mineral opaque structures were evident in the mid-caudal abdomen. On ultrasound, a right seminal vesicle with a reduction in diameter was observed, containing less echogenic material than the contralateral one, with five oval structures with a hyperechogenic contour and a central hypoechogenic area, forming acoustic shadowing. The left seminal vesicle presented with the usual characteristics. After bilateral vesiculectomy, the patient recovered well, with no further symptoms. The histopathological result was a suppurative/abscessive inflammatory process with an accumulation of proteinaceous material., (© 2024 American College of Veterinary Radiology.)

Diabetes (DM) patients have an increased risk (~50%) for sudden cardiac death (SCD), mostly as a result of ventricular arrhythmias. The molecular mechanisms involved remain partially defined. The potent proinflammatory lipid mediator leukotriene (LT) B4, is pathologically elevated in DM compared to nondiabetic patients, resulting in increased LTB4 accumulation in heart, leading to an increased risk for life-threatening proarrhythmic signatures. We used electrophysiology, immunofluorescence, and confocal microscopy approaches to evaluate LTB4 cellular effects in guinea pig heart and ventricular myocytes. We have observed that LTB4 is increased in multiple mouse models (C57BL/6 J/Lep ob/ob and PANIC-ATTAC) of DM, promotes profound cellular arrhythmogenesis (spontaneous beats and early after depolarizations, EADs), and severely depresses the rapidly activating delayed rectifier K current (hERG1/I Kr ) density in HEK293 cells and guinea pig ventricular myocytes. We have further found that guinea pigs challenged with LTB4 displayed a significantly prolonged QT interval, and that this can be prevented with LTB4R inhibition, suggesting that preventing such LTB4R effects may be therapeutically beneficial in DM. Our data suggests that a further elucidation of LTB4 vulnerable substrates, and how this leads to ventricular arrhythmias, is likely to lead to continued improvements in management options, and the development of new therapies for prevention of SCD in DM patients., (© 2024 The Author(s). Journal of Cellular Physiology published by Wiley Periodicals LLC.)

Asthma is a chronic inflammatory disease with many patients failing to respond appropriately to pharmacotherapy. Thus, virgin coconut oil (VCO) can be an alternative therapy. Guinea pigs were divided into control (Ctrl), chronic allergic lung inflammation (Asth), Asth treated with dexamethasone (Asth + dexa), and Asth supplemented with VCO (Asth + VCO4). The tested animals were sensitized and challenged with ovalbumin. Relaxation induced by arachidonic acid (AA) was impaired in Asth, and this reduction was prevented by VCO (p = 0.0004), indicating formation of relaxing prostanoids, or the decrease of cysteinyl-leukotrienes by VCO. Furthermore, a possible negative modulation of β receptors/BKCa pathway by TGF–β in Asth was prevented by VCO (p = 0.0073). Finally, in Asth, Masson’s trichrome staining revealed airway remodeling and immunohistochemistry showed increased TGF-β expression in the lungs of Asth (p

Abstract Background Since there is no complete study of topographic features of thorax structures in guinea pigs, this study strives to define the exact topographic features of thorax structures. Objectives The aim of this study is to provide comprehensive topographic information about the location of the trachea, bronchi, lungs and heart inside the thoracic cavity in guinea pig, as well as to study the features of these structures, their proximity to other organs and comparative anatomical studies with CT scan images in living samples. Methods Ten adult male and healthy guinea pigs were selected. CT scan transverse images were taken. The morphometric parameters of the lungs, bronchi, trachea, heart, thoracic cavity and abdominal cavity were measured. Results In these studies, the position of organs such as the trachea, lungs and heart were monitored, and specified descriptions of CT scan images and anatomical observations were obtained. We realised that the heart in this animal was not inclined to the left, and due to the equal size of the lungs, the heart was almost on the midline. According to the measurements, 20.05% of the ventral cavity volume was thoracic cavity and 79.95% was abdominal cavity. Conclusions According to studies on guinea pigs, the right and left have the volume, and the heart is located between them on the midline without a tendency to the left. It seems that one of the reasons for the reluctance of the heart to the left and its placement on the midline in the guinea pig is that the volume of the two lungs is equal. In the case of guinea pigs, both numerical parameters are smaller than rabbits’, but close to it. One of the most important factors in this study is that none of the animals were euthanised, and all of samples were alive after our study.

Abstract We studied the inhibitory actions of docosahexaenoic acid (DHA) on the contractions induced by carbachol (CCh), angiotensin II (Ang II), and bradykinin (BK) in guinea pig (GP) gastric fundus smooth muscle (GFSM), particularly focusing on the possible inhibition of store-operated Ca2+ channels (SOCCs). DHA significantly suppressed the contractions induced by CCh, Ang II, and BK; the inhibition of BK-induced contractions was the strongest. Although all contractions were greatly dependent on external Ca2+, more than 80% of BK-induced contractions remained even in the presence of verapamil, a voltage-dependent Ca2+ channel inhibitor. BK-induced contractions in the presence of verapamil were not suppressed by LOE-908 (a receptor-operated Ca2+ channel (ROCC) inhibitor) but were suppressed by SKF-96365 (an SOCC and ROCC inhibitor). BK-induced contractions in the presence of verapamil plus LOE-908 were strongly inhibited by DHA. Furthermore, DHA inhibited GFSM contractions induced by cyclopiazonic acid (CPA) in the presence of verapamil plus LOE-908 and inhibited the intracellular Ca2+ increase due to Ca2+ addition in CPA-treated 293T cells. These findings indicate that Ca2+ influx through SOCCs plays a crucial role in BK-induced contraction in GP GFSM and that this inhibition by DHA is a new mechanism by which this fatty acid inhibits GFSM contractions.

Botulinum neurotoxins (BoNT) are some of the most toxic proteins known and can induce respiratory failure requiring long-term intensive care. Treatment of botulism includes the administration of antitoxins. Monoclonal antibodies (mAbs) hold considerable promise as BoNT therapeutics and prophylactics, due to their potency and safety. A three-mAb combination has been developed that specifically neutralizes BoNT serotype A (BoNT/A), and a separate three mAb combination has been developed that specifically neutralizes BoNT serotype B (BoNT/B). A six mAb cocktail, designated G03-52-01, has been developed that combines the anti-BoNT/A and anti-BoNT/B mAbs. The pharmacokinetics and neutralizing antibody concentration (NAC) of G03-52-01 has been determined in guinea pigs, and these parameters were correlated with protection against an inhalation challenge of BoNT/A1 or BoNT/B1. Previously, it was shown that each antibody demonstrated a dose-dependent mAb serum concentration and reached maximum circulating concentrations within 48 h after intramuscular (IM) or intraperitoneal (IP) injection and that a single IM injection of G03-52-01 administered 48 h pre-exposure protected guinea pigs against an inhalation challenge of up to 93 LD50s of BoNT/A1 and 116 LD50s of BoNT/B1. The data presented here advance our understanding of the relationship of the neutralizing NAC to the measured circulating antibody concentration and provide additional support that a single IM or intravenous (IV) administration of G03-52-01 will provide pre-exposure prophylaxis against botulism from an aerosol exposure of BoNT/A and BoNT/B.