Expression of ß1- and ß2-adrenergic receptors in oral squamous cell carcinoma and their association with psychological and clinical factors.

BACKGROUND: Psychological stressors have been related to tumor progression through the activation of beta-adrenergic receptors (ß-AR) in several types of cancer. PURPOSE: This study aimed to investigate the expressions of ß1- and ß2-AR and their association with psychological and clinicopathological variables in patients with oral squamous cell carcinoma. METHODS: Tumor samples from 99 patients diagnosed with OSCC were subjected to immunohistochemical reaction to detect the expression of ß1-AR and ß2-AR. Anxiety and depression symptoms were assessed using the Beck Anxiety Inventory and Beck Depression Inventory (BDI), respectively. The Brunel Mood Scale was used for measuring affective mood states. RESULTS: Univariate analyzes revealed that higher expression of ß1-AR was associated with increased alcohol consumption (p = 0.032), higher education (p = 0.042), worse sleep quality (p = 0.044) and increased levels of pain related to the primary tumor (p < 0.001). Higher expression of ß2-AR was related with regional metastasis (p = 0.014), increased levels of pain related to the primary tumor (p = 0.044), anxiety (p < 0.001) and depressive (p = 0.010) symptoms and higher mood scores of angry (p = 0.010) and fatigue (p = 0.010). Multivariate analysis identified that patients with advanced clinical stage had lower ß1-AR expression (OR=0.145, 95% CI=0.025-0.828, p = 0.003). Higher anxiety symptoms and higher mood fatigue are independent factors for increased ß2-AR expression (OR=4256, 95% CI=1439-12606, p = 0.009; OR=3816, 95% CI=1258-11,573, p = 0.018, respectively). CONCLUSION: This study reveal that anxiety, fatigue symptoms, and clinical staging are associated with tumor expression of beta-adrenergic receptors in patients with oral cancer.

Effects of orchiectomy and testosterone replacement therapy on redox balance and salivary gland function in Wistar rats.

The objective of this study was to investigate the effects of orchiectomy (ORX) and testosterone replacement therapy (TRT) on redox balance and function of salivary glands. Forty-five young adult male Wistar rats (3 months old) were either castrated bilaterally or underwent fictitious surgery (SHAM) and were subsequently distributed into 3 groups: SHAM, ORX, and TRT (castrated rats that received an intramuscular injection of testosterone cypionate 10 mg/kg/weekly). All treatments started 4 weeks after castration (4 months old) and lasted 4 weeks (5 months old). At the end of treatment, pilocarpine-induced salivary secretion was collected to analyze salivary flow rate and biochemistry composition, and the parotid (PG) and submandibular (SMG) glands were sampled for redox balance markers and histomorphometric analyses. ORX increased salivary flow rate, calcium, phosphate, and chloride, and decreased total protein and amylase, while not changing the salivary buffer capacity, pH, sodium, and potassium compared to SHAM. TRT restored all salivary parameters to SHAM values. ORX increased oxidative lipid and protein damage, total antioxidant capacity, and uric acid in both salivary glands compared to SHAM. Superoxide dismutase, catalase, and glutathione peroxidase activities were greater only in the SMG of the ORX group in relation to SHAM. ORX decreased duct and acini area, while increasing connective tissue in the PG. On the other hand, ORX reduced duct area and increased acini area in the SMG compared to SHAM. TRT restored the redox balance and histomorphometric parameters to close to SHAM values in both salivary glands. Orchiectomy-induced salivary gland dysfunction was characterized by an increase in the salivary flow rate and changes in the secretion of total protein, amylase, and electrolytes, which are key factors, considered important for maintaining oral health status. To sum up, orchiectomy impaired the redox balance of the salivary glands. Our results also showed that TRT reversed the oxidative damage, morphological alterations, and salivary gland dysfunction induced by orchiectomy. Therefore, these results suggest an important action of testosterone on the redox balance and secretory ability of salivary glands.

Social isolation stress facilitates chemically induced oral carcinogenesis.

Social isolation has affected a large number of people and may lead to impairment of physical and mental health. Although stress resulting from social isolation may increase cancer progression, its interference on tumorigenesis is poorly known. In this study, we used a preclinical model to evaluate the effects of social isolation stress on chemically induced oral carcinogenesis. Sixty-two 21-day-old male Wistar rats were divided into isolated and grouped groups. After 90 days of age, the rats from both groups underwent oral carcinogenesis with 4-nitroquinoline 1-oxide (4NQO) for 20 weeks. All rats were assessed for depressive-like behavior and euthanized for oral squamous cell carcinoma (OSCC) diagnosis and measurement of inflammatory mediators in the tumor microenvironment. Social isolation stress increased the OSCC occurrence by 20.4% when compared to control. Isolated rats also showed higher tumor volume and cachexia than the grouped rats. Social isolation did not induce changes in the depressive-like behavior after carcinogenic induction. Tumors from stressed rats had increased levels of the inflammatory mediators, TNF-alpha, IL1-beta and MCP-1. The concentrations of TNF-alpha and MCP-1 were significantly increased in the large tumors from isolated animals. Higher tumor levels of TNF-alpha, IL-6, IL1-beta and MCP-1 were positively correlated with OSCC growth. This study provides the first evidence that social isolation stress may facilitate OSCC occurrence and tumor progression, an event accompanied by increased local levels of inflammatory mediators.

In situ melanoma of oral cavity: Diagnosis and treatment of a rare entity.

Oral melanoma is an extremely aggressive and rare tumor. Commonly, oral melanomas are diagnosed as invasive tumors, which considerably reduces the chances of cure. In situ oral melanomas being exceedingly rare, which makes its clinicopathological and prognostic characteristics poorly known. Herein, we report a case of 67-year-old non-white woman with a large black patch on the maxillary alveolar mucosa. A biopsy was made and microscopical analysis revealed moderate atypical junctional melanocytic. Tumor cells were positive for S100 (Polyclonal), Melan-A (Clone A103) and Melanosome (HMB-45). The diagnosis of in situ oral melanoma was made and the patient was treated surgically with partial maxillectomy and rehabilitated with obturator prosthesis. Although extremely rare in situ melanomas should be considered in the differential diagnosis of non-invasive pigmented lesions of the oral mucosa.

Oral leukoplakia-epidemiological survey and histochemical analysis of 107 cases in Brazil.

OBJECTIVE: To perform an epidemiological survey comparing the cell proliferative activity of 107 cases of oral leukoplakia with their clinical and histopathological characteristics. MATERIALS AND METHODS: A cross-sectional, observational, and histological-histochemical study. The cases came from the Histopathological Diagnostic Service of UPF/RS and the School of Dentistry of Araçatuba FOA/UNESP/SP (1986-2016). The histopathological sections were stained using the silver staining (AgNOR) technique and the nuclei of 100 epithelial cells selected randomly were recorded to count the number of nucleolar organizer regions (NORs). The mean NORs per lesion were correlated to clinical and histological characteristics using ANOVA, at 5% significance. RESULTS: Most of the cases included men (62.62%), white (64.49%), and with an average age of 53.94 years. The most probable etiological factors were smoking (44.7%) and alcohol consumption (9.85%). The evolution time of most lesions was fast (33.65%), manifesting mainly in the form of plaques (70.37%) and without symptoms (58.88%). They were located mainly in the cheek mucosa (26.62%) and presented white color (66.35%), well-defined edges (59.81%), firm consistency (47.5%), and keratinized surface (49.53%). Etiological factor (p = 0.003), evolution time (p = 0.006), symptoms (p = 0.029), location (p = 0.020), consistency (p = 0.047), histopathological characteristics (p = 0.004), and superficial keratinization (p = 0.001) were statistically significant regarding the mean NORs of the leukoplakias studied. CLINICAL RELEVANCE: Oral leukoplakias caused by alcohol consumption and/or tobacco use, considering an evolution time of fewer than 12 months, asymptomatic, located in the lower lip or tongue, and with a firm consistency and increased superficial keratinization should be treated more aggressively by the clinician to avoid cancerization.

Pineal gland protects against chemically induced oral carcinogenesis and inhibits tumor progression in rats.

Clinical investigations suggest that melatonin suppression and circadian dysfunction may be related to cancer development in shift workers. Studies also show that melatonin suppression after pinealectomy increases cancer incidence in preclinical models. However, no study evaluated the influence of pinealectomy on oral cancer development. In the current study, we investigated the effects of pinealectomy on oral squamous cell carcinoma (OSCC) occurrence and progression in rats. Rats submitted to sham surgery were used as control. Pinealectomy promoted an increase of 140% in OSCC occurrence when compared to sham animals. Tumors from pinealectomized rats displayed a higher volume and thickness than the tumors from sham-operated animals. Pinealectomy induced atrophy of the epithelium adjacent to the oral lesions. Pinealectomized rats showed higher mean number of tumor-associated macrophages and eosinophils in the invasive front of OSCC. In addition, nuclear overexpression of ERK1/2 and p53 was also observed in the front of carcinomas from pinealectomized rats. These results reveal that pineal gland plays a protective role against oral carcinogenesis. The melatonin suppression caused by the pinealectomy might contribute to oral cancer development by acting on ERK1/2 and p53 pathways and regulating tumor inflammation.

High p16INK4a immunoexpression is not HPV dependent in oral leukoplakia.

OBJECTIVE: To evaluate the prevalence of HPV DNA detection in fresh tissue from oral leukoplakia by Linear Array assay, and its correlation with p16INK4a immunoexpression in the northwest region of the São Paulo state, Brazil. PATIENTS AND METHODS: Fifty patients diagnosed with oral leukoplakia were included in the study. Sociodemographic, clinicopathologic and lifestyle data, fresh tissue and formalin fixed paraffin embedded (FFPE) tissue samples were collected. The fresh tissue was stored at -80 °C and then submitted to further viral DNA detection by the Linear Array method. Immunohistochemical analysis for the p16INK4a expression was performed. RESULTS: Of the 50 patients included in the study, 62 % were men, and the age ranged from 25 to 82 years. Twenty-three (46 %) were elderly, 46 % were middle-aged adults, and only 12 % were young adults. Most patients were smokers (76 %), 14 % were former smokers, and 10 % were non-smokers. Most patients (56 %) were current drinkers, 22 % were ex-drinkers and 22 % were non-drinkers. Thirty-two percent of the lesions presented some degree of dysplasia. No lesions were positive to HPV by Linear Array detection. Thirty (60 %) OL had p16-low immunoexpression and 20 (40 %) had p16-high immunoexpression. CONCLUSION: HPV was not identified in the population studied. The high p16INK4a immunoexpression is not dependent on HPV in oral leukoplakia. Broader epidemiological studies are required to clarify the geographic variability in the prevalence of HPV in head and neck squamous cell carcinoma and oral potentially malignant lesions.

Mate tea (Ilex paraguariensis) improves bone formation in the alveolar socket healing after tooth extraction in rats.

OBJECTIVES: The objective of this study was to investigate the effects of mate tea (MT) [Ilex paraguariensis] on alveolar socket healing after tooth extraction. MATERIALS AND METHODS: Sixteen male rats were divided into MT and control groups. MT was administered by intragastric gavage at a dose of 20 mg/kg/day for 28 days before and 28 days after right maxillary incisor extraction. The control group received an equal volume of water. Histopathological and histometric analysis of the neoformed bone area and osteocyte density were performed, as well as immunohistochemical analysis of osteocalcin (OCN), receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), tartrate-resistant acid phosphatase (TRAP), and manganese superoxide dismutase (MnSOD) in the alveolar socket. Calcium, phosphorus, alkaline phosphatase (ALP) activity, total antioxidant capacity (TAC), and malondialdehyde (MDA) were measured in plasma, whereas TRAP activity was determined in serum. RESULTS: Histometry evidenced an increase in bone area (P < 0.0001) and osteocyte density (P < 0.0001). MT increased immunolabeling of MnSOD (P < 0.001), OCN (P < 0.0001), RANKL (P < 0.001), OPG (P < 0.0001), and TRAP (P < 0.001). Calcium and phosphorus concentrations did not differ between the groups. In addition, MT enhanced ALP (P < 0.05) and TRAP (P < 0.0001) activities. MT increased the TAC (P < 0.001), whereas it reduced MDA concentrations (P < 0.0001). CONCLUSIONS: MT increases bone area and osteocyte density in the alveolar socket healing on day 28 after tooth extraction. CLINICAL RELEVANCE: Regular MT ingestion improves the antioxidant defenses and bone formation, which is beneficial for alveolar socket bone healing after tooth extraction.

Validation of a new experimental model of extrusive luxation on maxillary molars of rats: a histological study.

BACKGROUND/AIM: The aim of this study was to test and validate a new model of extrusive luxation trauma on maxillary first molars of rats. MATERIAL AND METHODS: Forty adult male rats (Rattus norvegicus albinus, Wistar; weight = 230-250 g), 45 days old, were divided into eight groups (n = 5): control groups, in which animals were not subjected to any procedure and waited 1 day (GC1D) or 3 days (GC3D) for euthanasia, and experimental groups, in which animals were subjected to forces of 1100cN, 1300cN, or 1500cN and waited 1 or 3 days for euthanasia (GT1100/1D, GT1100/3D, GT1300/1D, GT1300/3D, GT1500/1D, GT1500/3D). In animals of the experimental groups, trauma was produced by an extrusive force in maxillary first right molars. Four-micrometer serial cuts stained with hematoxylin and eosin (HE) were made. Descriptive microscopic analysis of first upper right molar and semi-quantitative analysis (scores 1 to 4) of intensity of acute and chronic inflammation and vascular changes in the periodontal ligament and active and inactive external root resorption were conducted. The distribution of scores in the groups was compared using the Freeman-Halton extension of Fisher's exact test. The significance level was 5%. RESULTS: It was observed that vascular disorders (bleeding) on the periodontal ligament became more evident with increasing extrusive force. CONCLUSIONS: This new method was capable of generating histological changes, proving its secure application in this research area. The 1500cN force produced more damage on the periodontal ligament. CLINICAL RELEVANCE: The validation of a new experimental method can produce more reliable evidence in further research.

llex paraguariensis decreases oxidative stress in bone and mitigates the damage in rats during perimenopause.

During perimenopause, oxidative stress increases, which may result in disruption of bone turnover, and consequently in osteoporosis. The use of antioxidants may be an effective nutritional approach to reducing osteoporosis in this period of life. Mate tea (MT) (Ilex paraguariensis), a typical and inexpensive beverage consumed in the Brazilian south-east, Argentina and Uruguay, increases antioxidant defense. Our hypothesis was that MT would decrease oxidative stress and mitigate bone deterioration. To test this, we analyzed oxidative stress markers of bone turnover, and local and systemic markers of bone metabolism of rats during natural perimenopause. Female Wistar rats (aged 16months) in proven perimenopause period received 20mg/kgBW/day of mate tea, by gavage (PM+MT Group, n=10) or water (PM Group, n=10). Female rats aged 4months (AD Group, n=10) received water. The treatment period was four weeks. MT minimized the deterioration of rat microarchitecture, characterized by increase in the bone trabecular area, number of osteocytes and areal bone mineral density. These results were accompanied by a lower level of malondialdehyde, an oxidative stress marker, in femoral tissue homogenate. Plasmatic tartrate-resistant acid phosphatase, a typical osteoclastic function marker, decreases after treatment, indicating a decrease in osteoclastic function. MT also modified the immunostaining pattern of bone metabolism markers, decreasing the receptor activator of nuclear factor kappa-B ligant (RANKL), superoxide dismutase isoform 2 (SOD2) and increasing osteoprotegerin (OPG), a decoy receptor for the RANKL, which positively modulates bone mass. These results suggested MT was capable of decreasing bone resorption by inhibiting the osteoclastogenesis in a RANKL-dependent signaling pathway activated by oxidative stress. Taken together, the results indicated that MT minimized bone loss in perimenopause and this effect is at least partly due to the decrease in oxidative stress, confirming our hypothesis.

Extra-Gingival Pyogenic Granuloma Displacing Teeth.

Pyogenic granuloma is a common cause of growth of soft tissue in the oral cavity, especially in the gingiva. It is mainly associated with local and chronic irritants besides hormonal changes during pregnancy. Here, the authors present an unusual patient of an extra-gingival pyogenic granuloma with large dimensions and displacing teeth arising in a male patient. This is an interesting patient to be reported due to its exacerbated and atypical clinical features.

Kallikrein 4 and matrix metalloproteinase-20 immunoexpression in malignant, benign and infiltrative odontogenic tumors.

CONTEXT: Matrix metalloproteinase-20 (MMP20) (enamelysin) and kallikrein 4 (KLK4) are enzymes secreted by ameloblasts that play an important role in enamel matrix degradation during amelogenesis. However, studies have shown that neoplastic cells can produce such enzymes, which may affect the tumor infiltrative and metastatic behaviors. AIMS: The aim of this study is to assess the biological role of MMP20 and KLK4 in odontogenic tumors. MATERIALS AND METHODS: The enzymes were analyzed immunohistochemically in ameloblastoma, adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor, keratocystic odontogenic tumor with or without recurrence and odontogenic carcinoma. STATISTICAL ANALYSIS USED: Clinicopathological parameters were statistically correlated with protein expression using the Fisher's exact test. Kruskal-Wallis and Wilcoxon-independent methods were used to evaluate the differences in median values. RESULTS: Positive Immunoexpression was detected in all benign lesions, with a prevalence of 75-100% immunolabeled cells. Patients were predominantly young, Caucasian, female, with slow-growing tumors located in the mandible causing asymptomatic swelling. No KLK4 expression was seen in carcinomas, and the amount of MMP20-positive cells varied between 20% and 80%. Rapid evolution, recurrence and age >60 years characterized the malignant nature of these lesions. CONCLUSIONS: Data showed that KLK4 and MMP20 enzymes may not be crucial to tumoral infiltrative capacity, especially in malignant tumors, considering the diversity and peculiarity of these lesions. The significant immunoexpression in benign lesions, remarkably in AOT, is likely associated with differentiated tumor cells that can produce and degrade enamel matrix-like substances. This would be expected since the histogenesis of odontogenic tumors commonly comes from epithelium that recently performed a secretory activity in tooth formation.

Condyloma acuminata in the tongue and palate of a sexually abused child: a case report.

BACKGROUND: Condyloma acuminata caused by human papilloma viruses, (HPV) is a sexually transmitted disease (STD) appearing most frequently as soft, pink cauliflower like growths in moist areas, such as the genitalia, mouth and other places. The disease is highly contagious, can appear singly or in groups, small or large. In children, the isolation of a sexually transmitted organism may be the first indication that an abuse has occurred. Although the presence of a sexually transmissible agent from a child beyond the neonatal period is suggestive of sexual abuse, exceptions do exist. CASE PRESENTATION: The authors report the clinical case of a five-year-old Caucasian male with lesions located in the dorsal surfaces of the posterior tongue and palate. Both lesions had a firm consistency, reddish appearance and presence of whitish areas and regions of ulceration. During the interview, the mother reported that the boy had been sexually abused. CONCLUSION: Sexually transmitted disease may occur during sexual abuse. Dentists as well as pediatricians have a role to play in identifying and treating these children. The diagnosis is essentially clinical (anamnesis and physical examination), but also the use of cytology eventually resorts to biopsy of the suspicious lesions for histological examination. The therapeutic option was the excision of the lesions.

Oral Focal Mucinosis: Clinical Case Presentation With a Focus on Esthetic and Functional Surgical Resolution.

INTRODUCTION: When planning excisional surgery, alterations in the oral mucosa, particularly in esthetically important areas, represent a challenge. For cases involving an exophytic lesion with a vegetative tumoral aspect, a clinician may prioritize obtaining a definitive diagnosis by histopathologic and histochemical examinations over the preservation of esthetics or maintenance of the involved tooth. CASE PRESENTATION: A painless, hard lesion with normal coloration was present in the maxillary left central incisor of a patient for at least 6 years. A biopsy was performed to preserve oral mucosa and a treatment plan was established that included endodontic retreatment and prosthetic restoration. The histopathologic diagnosis was oral focal mucinosis, an uncommon and poorly characterized type of lesion. CONCLUSION: A conservative biopsy of the lesion facilitated an accurate diagnosis, promoted the patient's comfort, and achieved satisfactory esthetic results.

Total spontaneous regression of a central giant cell granuloma after incisional biopsy: a four-year follow-up case report.

Central giant cell granuloma (CGCG) of the jaws represents a localized and benign neoplastic lesion sometimes characterized by aggressive osteolytic proliferation. The World Health Organization defines it as an intraosseous lesion composed of cellular and dense connective tissues that contain multiple hemorrhagic foci, an aggregation of multinucleated giant cells, and occasional bone tissue trabeculae. The origin of this lesion is uncertain; however, factors such as local trauma, inflammation, intraosseous hemorrhage, and genetic abnormalities have been identified as possible causes. CGCG generally affects those younger than 30 years and occurs more frequently in women (2:1). This lesion corresponds to approximately 7% of all benign tumors of the jaws, with prevalence in the anterior region of the jaw. Aggressive lesions are characterized by symptoms, such as pain, numbness, rapid growth, cortical perforation, root resorption, and a high recurrence rate after curettage. In contrast, nonaggressive CGCGs have a slow rate of growth, may contain sparse trabeculation, and are less likely to move teeth or cause root resorption or cortical perforation. Nonaggressive CGCGs are generally asymptomatic lesions and thus are frequently found on routine dental radiographs. Radiographically, the 2 forms of CGCG present as radiolucent, expansive, unilocular or multilocular masses with well-defined margins. The histopathology of CGCG is characterized by multinucleated giant cells, surrounded by round, oval, and spindle-shaped mononuclear cells, scattered in dense connective tissue with hemorrhagic and abundant vascularization foci. The final diagnosis is determined by histopathologic analysis of the biopsy specimen. The preferred treatment for CGCG consists of excisional biopsy, curettage with a safety margin, and partial or total resection of the affected bone. Conservative treatments include local injections of steroids, calcitonin, and antiangiogenic therapy. Drug treatment using antibiotics, painkillers, and corticosteroids and clinical and radiographic monitoring are necessary for approximately 10 days after surgery. There are only a few cases of spontaneous CGCG regression described in the literature; therefore, a detailed case report of CGCG regression in a 12-year-old boy with a 4-year follow-up is presented and compared with previous studies.

Expression of odontogenic ameloblast-associated protein, amelotin, ameloblastin, and amelogenin in odontogenic tumors: immunohistochemical analysis and pathogenetic considerations.

Screening for expression of amelogenesis-related proteins represents a powerful molecular approach to characterize odontogenic tumors and investigate their pathogenesis. In this study, we have examined the presence and distribution of odontogenic ameloblast-associated protein (ODAM), amelotin (AMTN), ameloblastin (AMBN), and amelogenin (AMEL) by immunohistochemistry in samples of adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor (CEOT), developing odontoma, ameloblastoma, calcifying cystic odontogenic tumor (CCOT), ameloblastic fibroma (AF), myxoma, odontogenic fibroma (OF), and reduced enamel epithelia (REE). Positive results were obtained in those tumors with epithelial component, except for AF, OF, and ameloblastoma. ODAM was found around mineralized structures (dystrophic calcifications) and CEOT's amyloid, whereas AMTN stained the eosinophilic material of AOTs. The CCOT transitory cells to ghost cells were strongly positive with all proteins except AMEL, and the REE as well as odontomas showed immunoexpression for ODAM, AMTN, AMBN, and AMEL similar to those found in normal rat tooth germs. Based on these results, some histopathogenetic theories were formulated.

Efeitos da radioterapia sobre as condições bucais de pacientes oncológicos / Effects of radiotherapy on the oral consitions of oncologic patients

o presente estudo avaliou as condições bucais de 50 pacientes oncológicos submetidos à radioterapia de cabeça e pescoço (rT). os exames clínicos foram realizados antes do tratamento, imediatamente após 30 dias da rT e 6 meses após a conclusão da rT. As condições periodontais foram avaliadas segundo os critérios do Periodontal screening and recording (Psr) e determinou-se a necessidade de tratamento odontológico. A presença de xerostomia, mucosite e outros efeitos colaterais da rT foi também avaliada. Os pacientes irradiados logo após o início da radioterapia desenvolvem severa mucosite, dermatite, disgeusia, xerostomia e, em menor extensão, candidose. Após a conclusão da radioterapia, 68% dos pacientes apresentavam mucosite grau III ou IV. Verificou-se que o desenvolvimento de mucosite dificulta a higiene bucal, o que colabora para exacerbar a inflamação nos tecidos periodontais. Os dados do presente estudo mostraram que a principal causa de abandono da RT e da severidade das sequelas da RT dependem das condições bucais dos pacientes antes do início do tratamento e da ausência de tratamento odontológico prévio à RT.