Asymmetric framework motion of TCRαß controls load-dependent peptide discrimination.

Mechanical force is critical for the interaction between an αß T cell receptor (TCR) and a peptide-bound major histocompatibility complex (pMHC) molecule to initiate productive T-cell activation. However, the underlying mechanism remains unclear. We use all-atom molecular dynamics simulations to examine the A6 TCR bound to HLA-A*02:01 presenting agonist or antagonist peptides under different extensions to simulate the effects of applied load on the complex, elucidating their divergent biological responses. We found that TCR α and ß chains move asymmetrically, which impacts the interface with pMHC, in particular the peptide-sensing CDR3 loops. For the wild-type agonist, the complex stabilizes in a load-dependent manner while antagonists destabilize it. Simulations of the Cß FG-loop deletion, which reduces the catch bond response, and simulations with in silico mutant peptides further support the observed behaviors. The present results highlight the combined role of interdomain motion, fluctuating forces, and interfacial contacts in determining the mechanical response and fine peptide discrimination by a TCR, thereby resolving the conundrum of nearly identical crystal structures of TCRαß-pMHC agonist and antagonist complexes.

Use of a barrier membrane to repair congenital hard palate defects and to close oronasal fistulae remaining after cleft palate repair: seven dogs (2019-2022).

OBJECTIVE: To describe the use of a barrier membrane in dogs for repair of congenital hard palate defects and closure of oronasal fistulae (ONF) remaining after previous cleft palate (CFP) repair. ANIMALS: 7 client-owned dogs. METHODS: The hard palate defect was closed with medially positioned flaps (Von Langenbeck technique) or pedicle flaps (2-flap palatoplasty) and a membrane composed of autologous auricular cartilage from the pinna or allogenous fascia lata underlying the mucoperiosteal flaps. RESULTS: All palate defects were considered to have a high risk of dehiscence based on their type and size and the characteristics of the surrounding tissue. The barrier membrane was used in 5 dogs for repair of congenital hard palate defects and in 2 dogs for closure of ONF remaining after previous CFP repair. Resolution of clinical signs occurred in all cases. Complete success (ie, complete closure of the palate defect and absence of clinical signs) was achieved in 5 dogs (4 with congenital hard palate defects and 1 with an ONF remaining after previous CFP repair). The persistent ONF in 1 dog with functional success (incomplete closure, but no clinical signs) was smaller than prior to surgery. CLINICAL RELEVANCE: Barrier membranes underlying mucoperiosteal flaps may constitute an alternative technique in dogs for repair of congenital hard palate defects and closure of ONF remaining after previous CFP repair.

Etiology, clinical presentation, and outcome of temporomandibular joint luxation in cats: 21 cases (2000-2018).

This study was performed to report etiology, clinical presentation, treatment, and outcome of temporomandibular joint (TMJ) luxation in 21 cats (2000-2018). TMJ luxation was diagnosed by either dental radiography or computed tomography (CT). Causes for TMJ luxation included altercation with a dog (38%), hit-by-car (19%), unknown (19%), fall (19%), and ran into inanimate object (5%). The most common complication was development of permanent malocclusion (24%), followed by reduced vertical mandibular range of motion (5%). Reduction of TMJ luxation was successful in 94.7% of the cases. Reduction of the TMJ luxation was significantly associated with time from injury to treatment. No other significant associations were observed between cause of injury, type of TMJ stabilization, and outcome. TMJ luxation in cats carries an excellent prognosis with early joint reduction and supportive care. Concurrent dental trauma and maxillofacial injuries are common, and all patients with head trauma must be stabilized and evaluated with a thorough examination.

Asymmetric framework motion of TCRαß controls load-dependent peptide discrimination.

Mechanical force is critical for the interaction between an αßT cell receptor (TCR) and a peptide-bound major histocompatibility complex (pMHC) molecule to initiate productive T-cell activation. However, the underlying mechanism remains unclear. We use all-atom molecular dynamics simulations to examine the A6 TCR bound to HLA-A*02:01 presenting agonist or antagonist peptides under different extensions to simulate the effects of applied load on the complex, elucidating their divergent biological responses. We found that TCR α and ß chains move asymmetrically, which impacts the interface with pMHC, in particular the peptide-sensing CDR3 loops. For the wild-type agonist, the complex stabilizes in a load-dependent manner while antagonists destabilize it. Simulations of the Cß FG-loop deletion, which reduces the catch bond response, and simulations with in silico mutant peptides further support the observed behaviors. The present results highlight the combined role of interdomain motion, fluctuating forces, and interfacial contacts in determining the mechanical response and fine peptide discrimination by a TCR, thereby resolving the conundrum of nearly identical crystal structures of TCRαß-pMHC agonist and antagonist complexes.

Surgical treatment for cleft palate in dogs yields excellent outcomes despite high rates of oronasal fistula formation: a narrative review.

Cleft palate is the most common congenital orofacial defect in dogs. Although this topic has been extensively studied in experimental dogs, current literature on clinical patients is limited to case reports and small case series studies with many individual opinions based on experience. This narrative review summarizes the literature of the last 10 years with application to clinical practice, focusing on the preparation of the patient until surgery, options for surgical management, and perioperative complications. Surgical treatment must be performed to obtain separation between the nasal/nasopharyngeal and oral/oropharyngeal passages. This will allow the dog to have independent function and reduce clinical signs associated with food, water, and other foreign material entering the respiratory tract. Surgical treatment has good to excellent outcomes when the procedure is carefully planned and appropriately executed despite the high rates of postoperative oronasal fistula reported.

Surgical Treatment and Outcome of Acquired Midline Palate Defects in Cats.

Acquired midline palate defects (PDE) affect the hard palate and/or soft palate, and result from trauma, commonly falling from a height or being hit by a motor vehicle. Additional life-threating injuries and costs associated with the treatment may delay the surgical treatment. This retrospective study describes signalment, cause, and extent of the PDE, and treatment in 25 cats. In addition, the outcome of the surgical repair is described in 19 (76%) cats. All defects were repaired within 5 days of the injury. Twenty (80%) cats were 4 years of age or younger. The most common rostral extent of the PDE was to the level of the third premolar tooth (n = 8; 32%), incisor teeth (n = 7; 28%), and fourth premolar tooth (n = 5; 20%). The soft palate laceration was present in all cases. Surgical therapy was successful in all cases with follow-up. The most common techniques used for the closure of the hard palate defect were bilateral pedicle flaps with lateral releasing incisions (n = 8; 32%), direct apposition of the oral mucosa (n = 7; 28%), bilateral pedicle flaps with lateral releasing incisions and interquadrant splinting (n = 5; 20%), and unilateral pedicle flap with one lateral releasing incision (n = 4; 16%). A tension-free closure by direct apposition of the edges was possible for the soft palate laceration. No oronasal fistulae were identified at follow-up. The only complication was malocclusion. The interquadrant splinting was most often used for PDE extending to the rostral portion of the hard palate (p < 0.05). The cats that suffered postoperative malocclusion were significantly more likely to have sustained temporomandibular joint injury, underwent CT scan, or had a feeding tube placed before discharge. The results of this retrospective study indicate that the early treatment (within 5 days) of the acquired longitudinal defects in the midline of the hard and soft palates is highly successful.

Dental Abnormalities in Immature Dogs with a History of Mandibular Fractures.

This study was performed to report the dental abnormalities encountered in immature dogs with a history of mandibular fracture. Dogs were included in the study if mandibular fractures were diagnosed by means of oral examination and diagnostic imaging, they were treated with non-invasive or minimally invasive methods, and there was a follow-up examination of at least 90 days after the initial presentation with the last follow-up visit occurring at 6 months of age or older. Eleven dogs met the inclusion criteria. Dental abnormalities occurred exclusively in those dogs that had sustained fracture of the mandibular body or fracture at the transition of mandibular body and mandibular ramus. A high number of developing permanent teeth located in or near the mandibular fracture were affected (73.5%). The most common dental abnormalities were failure of eruption or partial eruption (29.0%), resorption (22.6%), abnormal shape (19.4%), and enamel hypoplasia (16.1%). The majority of deciduous teeth (64.3%) in or near the mandibular fracture exfoliated uneventfully. Ten out of 11 dogs needed a surgical procedure to treat dental abnormalities after mandibular fracture healing. The development of the tooth germs located in or near a mandibular fracture is frequently affected. Radiographic evaluation of the area of trauma is recommended until eruption and full development of the teeth are completed.

Etiology, Clinical Presentation, and Outcome of Mandibular Fractures in Immature Dogs Treated with non-Invasive or Minimally Invasive Techniques.

This study was performed to report etiology, clinical presentation, and outcome of mandibular fractures in immature dogs treated with non-invasive or minimally invasive techniques. Immature dogs diagnosed with mandibular fractures from 2001 to 2016 were included in this study. Diagnosis of the mandibular fracture was achieved by oral examination and diagnostic imaging in the anesthetized dog. Twenty-nine immature dogs with 54 mandibular fractures were selected. Within the mandibular body, the regions of the developing permanent canine and first molar teeth were most commonly involved (46.4% and 35.0%, respectively). Within the mandibular ramus, 53.8% of the fractures were located in its ventral half, and 38.5% in the condylar process. Muzzling was applied in 72.4% of the dogs. All dogs had clinical healing with resolution of signs of pain and recovery of mandibular function. Mean time for clinical healing was 21 ± 9 days. Age of the dog and duration of muzzling were significantly associated with the time needed for clinical healing. In immature dogs, fractures of the mandibular body occur most commonly in the regions of the developing permanent canine and first molar teeth, while fractures of the mandibular ramus are most commonly found in its ventral half and the condylar process. Non-invasive or minimally invasive management of mandibular fractures in immature dogs carries a good prognosis regarding clinical healing and recovery of mandibular function. Dogs should be monitored for the development of dental abnormalities and/or skeletal malocclusion until permanent teeth have erupted and jaw growth is completed.

Oral and Maxillofacial Tumor Management - From Biopsy to Surgical Removal.

The main objective of oral and maxillofacial (OMF) tumor resection is to get local control of the disease. Many OMF tumors can be cured with wide or radical surgery, whereas others might only achieve temporary local control of the disease by removing infection and the source of pain, thereby improving the quality of life of the patient while keeping masticatory function. The standard of care on managing OMF tumors includes the diagnosis and identification of the local and distant extension of the disease to establish an appropriate treatment plan tailored for each patient. In this article, we provide a practical review of the current information related to staging, biopsy, and main surgical techniques for OMF tumor removal.

Building a three-dimensional model of early-stage zebrafish embryo brain.

We introduce a computational approach to build three-dimensional (3D) surface mesh models of the early-stage zebrafish brain primordia from time-series microscopy images. The complexity of the early-stage brain primordia and lack of recognizable landmarks pose a distinct challenge for feature segmentation and 3D modeling. Additional difficulty arises because of noise and variations in pixel intensity. We overcome these by using a hierarchical approach in which simple geometric elements, such as "beads" and "bonds," are assigned to represent local features and their connectivity is used to smoothen the surface while retaining high-curvature regions. We apply our method to build models of two zebrafish embryo phenotypes at discrete time points between 19 and 28 h post-fertilization and collect measurements to quantify development. Our approach is fast and applicable to building models of other biological systems, as demonstrated by models from magnetic resonance images of the human fetal brain. The source code, input scripts, sample image files, and generated outputs are publicly available on GitHub.

Concentrations of bisphenol-A in adults from the general population: A systematic review and meta-analysis.

BACKGROUND: Human bisphenol-A (BPA) exposure has been linked to adverse health effects even at low doses, which may be of potential public health concern. OBJECTIVE: To summarize BPA concentrations in general human population and their variability according to sex, geographic area, and analytical method. METHODS: Systematic review and meta-analysis of studies reporting BPA concentrations in adult human populations. Separate meta-analyses of median values were carried out for BPA in serum, creatinine-adjusted urinary BPA, and unadjusted urinary BPA concentrations using a random-effects model. Cochran's Q-statistic, I2 index, 95% prediction intervals (PIs), between-studies standard deviation (τ), and forest plots were applied to verify study heterogeneity. Sensitivity and subgroup analyses and weighted ANOVAs and meta-regressions were conducted. Funnel plots and Egger's tests were used to examine publication bias. RESULTS: Fifteen studies were included in the meta-analysis, totaling 28,353 participants. BPA was detected in over 90% of participants. The pooled creatinine-adjusted urinary BPA concentration was 1.76 µg/g (95% PI: 0.79-2.73), with individual estimates ranging between 1.20 and 2.41. The pooled estimate for unadjusted urinary BPA was 1.91 µg/l (95% PI: 0-3.97), ranging between 0.81 and 3.50, while the pooled estimate for serum BPA was 1.75 µg/l (95% PI: 0-10.58), ranging between 0.34 and 3.76. No differences were found by sex, geographic area or analytical technique. Larger sample sizes were associated with lower BPA concentrations. There was large heterogeneity across studies, whereas data for urinary BPA levels suggested a publication bias affecting research in low exposed populations. CONCLUSION: This first meta-analysis of human BPA concentrations highlights a widespread population exposure to BPA. Although there was high heterogeneity across studies, the expected range of estimated human BPA concentrations suggests that potential health risks are unlikely. Further studies are warranted to better characterize the epidemiology of human BPA exposure, accounting for ethnic, geographic, individual and environmental variability.

Locoregional Anesthesia of the Head.

Locoregional (local and regional) anesthesia is used routinely during surgical procedures of the head. The goal of this article is to provide a practical guide for the clinician to safely perform different techniques in dogs and cats and to minimize the risk of complications associated with locoregional anesthesia.

Management and Outcome of Maxillofacial Trauma in a 9-Week-Old Dog.

This case report describes diagnosis, treatment, and outcome of maxillofacial trauma in a 9-week-old shih tzu. In addition to an open left mandibular body fracture and a right condylar process fracture, there were several relatively stable and minimally displaced right maxillary fractures. The torn soft tissues associated with the left mandibular body fracture were sutured closed, and a tape muzzle was placed. Due to sufficient fracture healing at the 2-week recheck examination, the tape muzzle was removed. The 6-week reexamination confirmed continued healing and recovery. Anesthesia was performed at the 5.5-month reexamination when the dog was 8 months old, revealing the presence of persistent deciduous teeth, linguoverted, malformed, and partially erupted permanent teeth, and asymmetric skeletal malocclusion (in addition to the breed-specific mandibular mesioclusion). Persistent deciduous teeth and linguoverted and malformed permanent teeth were extracted to allow for normal opening and closing of the mouth without traumatic occlusion. Long-term follow-up is recommended in juvenile dogs with maxillofacial injuries in order to prevent, recognize, and treat dental complications resulting from the trauma.

Fracture Limits of Maxillary Fourth Premolar Teeth in Domestic Dogs Under Applied Forces.

A cadaveric study was performed to investigate the external mechanical forces required to fracture maxillary fourth premolar teeth in domestic dogs and describe a clinically relevant model of chewing forces placed on functionally important teeth in which fracture patterns are consistent with those defined by the American Veterinary Dental College (AVDC). Twenty-four maxillary fourth premolar teeth were harvested from dog cadavers. Samples consisted of teeth with surrounding alveolar bone potted in polycarbonate cylinders filled with acrylic. The cylinders were held by an aluminum device at an angle of 60° with respect to the ground. An axial compression test was performed, creating a force upon the occluso-palatal aspects of the main cusps of the crowns of the teeth. The highest compressive force prior to failure was considered the maximum force sustained by the teeth. Results showed the mean maximum force (± SD) sustained by the tested teeth at the point of fracture was 1,281 N (± 403 N) at a mean impact angle (± SD) of 59.7° (± 5.2°). The most common fracture type that occurred among all samples was a complicated crown fracture (n = 12), followed by an uncomplicated crown fracture (n = 6), complicated crown-root fracture (n = 5), and uncomplicated crown-root fracture (n = 1). There was no statistically significant correlation between dog breed, age, weight, impact angle, crown height or crown diameter, and the maximum force applied at the point of fracture. The only independent variable that remained significantly associated with maximum force was the crown height to diameter ratio (p = 0.005), suggesting that a decreased ratio increases tooth fracture resistance. The methodology described herein has been successful in creating a pattern of fracture of maxillary fourth premolar teeth consistent with that defined by the AVDC under angled compression at forces within the maximum chewing capability of the average domestic dog.

Isolation of thermotolerant Vermamoeba vermiformis strains from water sources in Lanzarote Island, Canary Islands, Spain.

In this study, twenty water samples were collected in the island of Lanzarote, Canary Islands, Spain in order to check for the presence of V. vermiformis strains in these samples. Water samples were cultured on 2% Non-Nutrient Agar (NNA) plates covered with a thin layer of heat killed E. coli and checked daily for the presence of Vermamoeba. After a week, V. vermiformis amoebae were observed in 2 of the 20 processed samples (10%) incubated at room temperature and 37°C. Molecular characterization was carried out by amplifying the 18S rDNA gene and DNA sequencing in order to confirm the identity of the isolated amoebic strains. To the best of our knowledge, this is the first report on the presence of FLA in environmental sources in Lanzarote Island and the first report of Vermamoeba vermiformis in water sources in this island. Furthermore, the two strains isolated in this study were collected in recreational areas with close contact with humans and thus awareness should be raised.

Isolation and Molecular Identification of Vermamoeba vermiformis Strains from Soil Sources in El Hierro Island, Canary Islands, Spain.

Free-living amoebae (FLA) are widely distributed protozoa in the environment and have been isolated from many sources such as dust, soil and water. Furthermore, some genera/species of FLA such as Naegleria fowleri, Balamuthia mandrillaris and Acanthamoeba spp. are also able to cause opportunistic infections in humans and other animals. More recently, FLA have been reported to be environmental carriers of pathogenic bacteria, fungi and viruses, and thus have gained further importance from the public health point of view. Among them, Acanthamoeba spp. and Vermamoeba vermiformis have been described in many occasions as the most common carriers of pathogens of high medical relevance such as Legionella pneumophila and Mycobacterium spp. In this study, 24 soil samples were collected from the island of El Hierro, Canary Islands, Spain, in order to check for the presence of V. vermiformis strains in these samples. Soil samples were cultured on 2 % non-nutrient agar plates covered with a thin layer of heat-killed E. coli and checked daily for the presence of Vermamoeba. After a week, V. vermiformis amoebae were observed in 5 of the 24 processed samples (20.8 %) incubated at room temperature and 37 °C. Molecular characterization was carried out by amplifying the 18S rDNA gene and DNA sequencing, confirming that the isolated strains belonged to Vermamoeba vermiformis species. The high percentage of V. vermiformis in the studied soil sources should raise awareness in the region since these amoebae are potential environmental carriers of pathogens of high medical relevance.

Mast cells and its relation to collagen and VEGF in oral inflammatory lesions.

BACKGROUND: The aim of this study was to evaluate the population of intact and degranulated MCs in oral inflammatory lesions. METHODS: A cross sectional study of 48 samples, including inflammatory fibrous hyperplasia, pyogenic granulomas, periapical granulomas and radicular cysts, was performed. Samples of normal gingival mucosa were used as controls. The degree of edema and lymphoplasmacytic infiltrate was determined by the analysis of hematoxylin-eosin (HE)-stained sections. To determine the collagen fibers contents and correlate it with the MC count, sections stained with Sirius red and Toluidine blue were used. Immunohistochemistry with an antivascular endothelial growth factor (VEGF) was also used to count endothelial cells. RESULTS: Although the total number of intact MCs was higher in the oral inflammatory lesions, these differences were not statistically significant (P=0.33). There were statistically significant differences between the numbers of degranulated MCs from the lesions and those from the normal oral mucosae (P=0.001) and a positive correlation between the number of MCs and the degree of inflammation (P<0.001). The MC count did not correlate with the collagen fibers or VEGF positive cells (P>0.05). CONCLUSIONS: The involvement of MCs in the pathogenesis of the oral inflammatory lesions is suggested. However, there was no positive correlation with these cells and collagen fibers or angiogenesis in the lesions studied.

Endosymbiotic Mycobacterium chelonae in a Vermamoeba vermiformis strain isolated from the nasal mucosa of an HIV patient in Lima, Peru.

In March 2010, a 35 year-old HIV/AIDS female patient was admitted to hospital to start treatment with Highly Active Antiretroviral Therapy (HAART) since during a routine control a dramatic decrease in the CD4(+) levels was detected. At this stage, a nasal swab from each nostril was collected from the patient to include it in the samples for the case study mentioned above. Moreover, it is important to mention that the patient was diagnosed in 2009 with invasive pneumococcal disease, acute cholecystitis, pancreatitis and pulmonary tuberculosis. The collected nasal swabs from both nostrils were positive for Vermamoeba vermiformis species which was identified using morphological and PCR/DNA sequencing approaches. Basic Local Alignment Search Tool (BLAST) homology and phylogenetic analysis confirmed the amoebic strain to belong to V.vermiformis species. Molecular identification of the Mycobacterium strain was carried out using a bacterial universal primer pair for the 16S rDNA gene at the genus level and the rpoB gene was amplified and sequenced as previously described to identify the Mycobacterium species (Shin et al., 2008; Sheen et al., 2013). Homology and phylogenetic analyses of the rpoB gene confirmed the species as Mycobacterium chelonae. In parallel, collected swabs were tested by PCR and were positive for the presence of V.vermiformis and M.chelonae. This work describes the identification of an emerging bacterial pathogen,M.chelonae from a Free-Living Amoebae (FLA) strain belonging to the species V.vermiformis that colonized the nasal cavities of an HIV/AIDS patient, previously diagnosed with TB. Awareness within clinicians and public health professionals should be raised, as pathogenic agents such as M.chelonae may be using FLA to propagate and survive in the environment.

Isolation and characterization of Acanthamoeba strains from soil samples in Gran Canaria, Canary Islands, Spain.

Free-living Amoebae of Acanthamoeba genus include non-pathogenic and pathogenic strains that are currently classified in 18 different genotypes, T1-T18. In this study, a survey was carried out to evaluate the presence of Acanthamoeba strains in soil samples collected between 2012 and 2013 in Gran Canaria Island, Canary Islands, Spain. Samples were inoculated onto non-nutrient agar (NNA) plates and were checked for the presence of Acanthamoeba. Identification of Acanthamoeba strains was based on the morphology of the cyst and trophozoite forms. Subsequently, positive samples were cloned for their molecular characterization at the genotype level by sequencing the DF3 region located in the 18S rDNA gene of Acanthamoeba as previously described. Sequencing results revealed the presence of T2, T5 and T4 genotypes within the studied samples. To the best of our knowledge, this is the first report demonstrating the presence of Acanthamoeba in Gran Canaria Island and the first study at the genotype level in the Canary Islands.