726 resultados para Pathway Model


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There is increasing epidemiological and molecular evidence that cutaneous melanomas arise through multiple causal pathways. The purpose of this study was to explore the relationship between germline and somatic mutations in a population-based series of melanoma patients to reshape and refine the divergent pathway model for melanoma. Melanomas collected from 123 Australian patients were analyzed for melanocortin-1 receptor (MC1R) variants and mutations in the BRAF and NRAS genes. Detailed phenotypic and sun exposure data were systematically collected from all patients. We found that BRAF-mutant melanomas were significantly more likely from younger patients and those with high nevus counts, and were more likely in melanomas with adjacent neval remnants. Conversely, BRAF-mutant melanomas were significantly less likely in people with high levels of lifetime sun exposure. We observed no association between germline MC1R status and somatic BRAF mutations in melanomas from this population. BRAF-mutant melanomas have different origins from other cutaneous melanomas. These data support the divergent pathways hypothesis for melanoma, which may require a reappraisal of targeted cancer prevention activities.

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Gifted students who have a reading disability have learning characteristics that set them apart from their peers. The ability to read impacts upon all areas of the formal curriculum in which print-based texts are common. Therefore, the full intellectual development of gifted students with a reading disability can be repressed because their access to learning opportunities is reduced. When the different learning needs caused by concomitant giftedness and reading disability are not met, it can have serious implications for both academic achievement and the social-emotional wellbeing of these students. In order to develop a deeper understanding of this vulnerable group of students, this study investigated the learning characteristics of gifted students with a reading disability. Furthermore, it investigated how the learning characteristics of these students impact upon their lived experiences. Since achievement and motivation have been shown to be closely linked to self-efficacy, self-efficacy theory underpinned the conceptual framework of the study. The study used a descriptive case study approach to document the lived experiences of gifted students with a reading disability. Nine participants aged between 11 and 18, who were formally identified as gifted with a reading disability, took part in the study. Data sources in the case study database included: cognitive assessments, such as WISC assessments, Stanford Binet 5, or the Raven's Standard Progressive Matrices; the WIAT II reading assessment; the Reader Self-Perception Scale; document reviews; parent and teacher checklists designed to gain information about the students' learning characteristics; and semi-structured interviews with students. The study showed that gifted students with a reading disability display a complex profile of learning strengths and weaknesses. As a result, they face a daily struggle of trying to reconcile the confusion of being able to complete some tasks to a high level, while struggling to read. The study sheds light on the myriad of issues faced by the students at school. It revealed that when the particular learning characteristics and needs of gifted students with a reading disability are recognised and met, these students can experience academic success, and avoid the serious social-emotional complications cited in previous studies. Indeed, rather than suffering from depression, disengagement from learning, and demotivation, these students were described as resilient, independent, determined, goal oriented and motivated to learn and persevere. Notably, the students in the study had developed effective coping strategies for dealing with the daily challenges they faced. These strategies are outlined in the thesis together with the advice students offered for helping other gifted students with a reading disability to succeed. Their advice is significant for all teachers who wish to nurture the potential of those students who face the challenge of being gifted with a reading disability, and for the parents of these students. This research advances knowledge pertaining to the theory of self-efficacy, and self-efficacy in reading specifically, by showing that although gifted students with a reading disability have low self-efficacy, the level is not the same for all aspects of reading. Furthermore, despite low self-efficacy in reading these students remained motivated. The study also enhances existing knowledge in the areas of gifted education and special education because it documents the lived experience of gifted students with a specific learning disability in reading from the students' perspectives. Based on a synthesis of the literature and research findings, an Inclusive Pathway Model is proposed that describes a framework to support gifted students with a reading disability so that they might achieve, and remain socially and emotionally well-adjusted. The study highlights the importance of clear identification protocols (such as the use of a range of assessment sources, discussions with students and parents, and an awareness of the characteristics of gifted students with a reading disability) and support mechanisms for assisting students (for example, differentiated reading instruction and the use of assistive technology).

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Objectives The p38 mitogen-activated protein kinase (MAPK) signal transduction pathway is involved in a variety of inflammatory responses, including cytokine generation, cell differentiation proliferation and apoptosis. Here, we examined the effects of systemic p38 MAPK inhibition on cartilage cells and osteoarthritis (OA) disease progression by both in vitro and in vivo approaches. Methods p38 kinase activity was evaluated in normal and OA cartilage cells by measuring the amount of phosphorylated protein. To examine the function of p38 signaling pathway in vitro, normal chondrocytes were isolated and differentiated in the presence or absence of p38 inhibitor; SB203580 and analysed for chondrogenic phenotype. Effect of systemic p38 MAPK inhibition in normal and OA (induced by menisectomy) rats were analysed by treating animals with vehicle alone (DMS0) or p38 inhibitor (SB203580). Damage to the femur and tibial plateau was evaluated by modified Mankin score, histology and immunohistochemistry. Results Our in vitro studies have revealed that a down-regulation of chondrogenic and increase of hypertrophic gene expression occurs in the normal chondrocytes, when p38 is neutralized by a pharmacological inhibitor. We further observed that the basal levels of p38 phosphorylation were decreased in OA chondrocytes compared with normal chondrocytes. These findings together indicate the importance of this pathway in the regulation of cartilage physiology and its relevance to OA pathogenesis. At in vivo level, systematic administration of a specific p38 MAPK inhibitor, SB203580, continuously for over a month led to a significant loss of proteoglycan; aggrecan and cartilage thickness. On the other hand, SB203580 treated normal rats showed a significant increase in TUNEL positive cells, cartilage hypertrophy markers such as Type 10 collagen, Runt-related transcription factor and Matrix metalloproteinase-13 and substantially induced OA like phenotypic changes in the normal rats. In addition, menisectomy induced OA rat models that were treated with p38 inhibitor showed aggravation of cartilage damage. Conclusions In summary, this study has provided evidence that the component of the p38 MAPK pathway is important to maintain the cartilage health and its inhibition can lead to severe cartilage degenerative changes. The observations in this study highlight the possibility of using activators of the p38 pathway as an alternative approach in the treatment of OA.

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Introduction: Ankylosing spondylitis (AS) is unique in its pathology where inflammation commences at the entheses before progressing to an osteoproliferative phenotype generating excessive bone formation that can result in joint fusion. The underlying mechanisms of this progression are poorly understood. Recent work has suggested that changes in Wnt signalling, a key bone regulatory pathway, may contribute to joint ankylosis in AS. Using the proteoglycan-induced spondylitis (PGISp) mouse model which displays spondylitis and eventual joint fusion following an initial inflammatory stimulus, we have characterised the structural and molecular changes that underlie disease progression. Methods: PGISp mice were characterised 12 weeks after initiation of inflammation using histology, immunohistochemistry (IHC) and expression profiling. Results: Inflammation initiated at the periphery of the intervertebral discs progressing to disc destruction followed by massively excessive cartilage and bone matrix formation, as demonstrated by toluidine blue staining and IHC for collagen type I and osteocalcin, leading to syndesmophyte formation. Expression levels of DKK1 and SOST, Wnt signalling inhibitors highly expressed in joints, were reduced by 49% and 63% respectively in the spine PGISp compared with control mice (P < 0.05) with SOST inhibition confirmed by IHC. Microarray profiling showed genes involved in inflammation and immune-regulation were altered. Further, a number of genes specifically involved in bone regulation including other members of the Wnt pathway were also dysregulated. Conclusions: This study implicates the Wnt pathway as a likely mediator of the mechanism by which inflammation induces bony ankylosis in spondyloarthritis, raising the potential that therapies targeting this pathway may be effective in preventing this process.

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Ultraviolet radiation (UV) is the carcinogen that causes the most common malignancy in humans – skin cancer. However, moderate UV exposure is essential for producing vitaminDin our skin. VitaminDincreases the absorption of calcium from the diet, and adequate calcium is necessary for the building and maintenance of bones. Thus, low levels of vitamin D can cause osteomalacia and rickets and contribute to osteoporosis. Emerging evidence also suggests vitamin D may protect against falls, internal cancers, psychiatric conditions, autoimmune diseases and cardiovascular diseases. Since the dominant source of vitamin D is sunlight exposure, there is a need to understand what is a “balanced” level of sun exposure to maintain an adequate level of vitamin D but minimise the risks of eye damage, skin damage and skin cancer resulting from excessive UV exposure. There are many steps in the pathway from incoming solar UV to the eventual vitamin D status of humans (measured as 25-hydroxyvitamin D in the blood), and our knowledge about many of these steps is currently incomplete. This project begins by investigating the levels of UV available for synthesising vitamin D, and how these levels vary across seasons, latitudes and times of the day. The thesis then covers experiments conducted with an in vitro model, which was developed to study several aspects of vitamin D synthesis. Results from the model suggest the relationship between UV dose and vitamin D is not linear. This is an important input into public health messages regarding ‘safe’ UV exposure: larger doses of UV, beyond a certain limit, may not continue to produce vitamin D; however, they will increase the risk of skin cancers and eye damage. The model also showed that, when given identical doses of UV, the amount of vitamin D produced was impacted by temperature. In humans, a temperature-dependent reaction must occur in the top layers of human skin, prior to vitamin D entering the bloodstream. The hypothesis will be raised that cooler temperatures (occurring in winter and at high latitudes) may reduce vitamin D production in humans. Finally, the model has also been used to study the wavelengths of UV thought to be responsible for producing vitamin D. It appears that vitamin D production is limited to a small range of UV wavelengths, which may be narrower than previously thought. Together, these results suggest that further research is needed into the ability of humans to synthesise vitamin D from sunlight. In particular, more information is needed about the dose-response relationship in humans and to investigate the proposed impact of temperature. Having an accurate action spectrum will also be essential for measuring the available levels of vitamin D-effective UV. As this research continues, it will contribute to the scientific evidence-base needed for devising a public health message that will balance the risks of excessive UV exposure with maintaining adequate vitamin D.

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Objectives: To explore whether people's organ donation consent decisions occur via a reasoned and/or social reaction pathway. --------- Design: We examined prospectively students' and community members' decisions to register consent on a donor register and discuss organ donation wishes with family. --------- Method: Participants completed items assessing theory of planned behaviour (TPB; attitude, subjective norm, perceived behavioural control (PBC)), prototype/willingness model (PWM; donor prototype favourability/similarity, past behaviour), and proposed additional influences (moral norm, self-identity, recipient prototypes) for registering (N=339) and discussing (N=315) intentions/willingness. Participants self-reported their registering (N=177) and discussing (N=166) behaviour 1 month later. The utility of the (1) TPB, (2) PWM, (3) augmented TPB with PWM, and (4) augmented TPB with PWM and extensions was tested using structural equation modelling for registering and discussing intentions/willingness, and logistic regression for behaviour. --------- Results: While the TPB proved a more parsimonious model, fit indices suggested that the other proposed models offered viable options, explaining greater variance in communication intentions/willingness. The TPB, augmented TPB with PWM, and extended augmented TPB with PWM best explained registering and discussing decisions. The proposed and revised PWM also proved an adequate fit for discussing decisions. Respondents with stronger intentions (and PBC for registering) had a higher likelihood of registering and discussing. --------- Conclusions: People's decisions to communicate donation wishes may be better explained via a reasoned pathway (especially for registering); however, discussing involves more reactive elements. The role of moral norm, self-identity, and prototypes as influences predicting communication decisions were highlighted also.

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This paper will explore how a general education can contribute successfully to vocational outcomes using both Participatory Action Research (PAR) and Program Theory methodology. The paper will focus on the development aspects of ‘marrying’ vocational and general education including engagement processes, student, teacher, institute and employer preparation and the pathway possibilities that emerge. Successful cases presented include the: Healthy Futures program (pathways into the Health and Allied industries); Accounting Pathways program (simultaneously studying a general Accounting subject and a Certificate III vocational qualification); and Sustainable Sciences initiative (development of a vocational qualification that focuses on the emerging renewable energy industry and is linked to school science programs). The case studies have been selected because they are unique in character and application and can be used as a basis for future program development in other settings or curriculum areas.

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To evaluate whether luminance contrast discrimination losses in amblyopia on putative magnocellular (MC) and parvocellular (PC) pathway tasks reflect deficits at retinogeniculate or cortical sites. Fifteen amblyopes including six anisometropes, seven strabismics, two mixed and 12 age-matched controls were investigated. Contrast discrimination was measured using established psychophysical procedures that differentiate MC and PC processing. Data were described with a model of the contrast response of primate retinal ganglion cells. All amblyopes and controls displayed the same contrast signatures on the MC and PC tasks, with three strabismics having reduced sensitivity. Amblyopic PC contrast gain was similar to electrophysiological estimates from visually normal, non-human primates. Sensitivity losses evident in a subset of the amblyopes reflect cortical summation deficits, with no change in retinogeniculate contrast responses. The data do not support the proposal that amblyopic contrast sensitivity losses on MC and PC tasks reflect retinogeniculate deficits, but rather are due to anomalous post-retinogeniculate cortical processing of retinal signals.

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Introduction: Degradative enzymes, such as A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) and matrix metalloproteinases (MMPs), play key roles in osteoarthritis (OA) development. The aim of the present study was to investigate if cross-talk between subchondral bone osteoblasts (SBOs) and articular cartilage chondrocytes (ACCs) in OA alters the expression and regulation of ADAMTS5, ADAMTS4, MMP-1, MMP-2, MMP-3, MMP-8, MMP-9 and MMP-13, and also to test the possible involvement of mitogen activated protein kinase (MAPK) signaling pathway during this process. Methods: ACCs and SBOs were isolated from normal and OA patients. An in vitro co-culture model was developed to study the regulation of ADAMTS and MMPs under normal and OA joint cross-talk conditions. MAPK-ERK inhibitor, PD98059 was applied to delineate the involvement of specific pathway during this interaction process. Results: Indirect co-culture of OA SBOs with normal ACCs resulted in significantly increased expression of ADAMTS5, ADAMTS4, MMP-2, MMP-3 and MMP-9 in ACCs, whereas co-culture of OA ACCs led to increased MMP-1 and MMP-2 expression in normal SBOs. The upregulation of ADAMTS and MMPs under these conditions was correlated with activation of the MAPK-ERK1/2 signaling pathway and the addition of the MAPK-ERK inhibitor, PD98059, reversed the overexpression of ADAMTS and MMPs in co-cultures. Conclusion: In summary, we believe, these results add to the evidence that in human OA, altered bi-directional signals transmitted between SBOs and ACCs significantly impacts the critical features of both cartilage and bone by producing abnormal levels of ADAMTS and MMPs. Furthermore, we have demonstrated for the first time that this altered cross-talk was mediated by the phosphorylation of MAPK-ERK1/2 signaling pathway.

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Hyperhomocysteinemia (hHcy) has been associated with an increased risk of cardiovascular disease and stroke. Essential hypertension (EH), a polygenic condition, has also been associated with increased risk of cardiovascular related disorders. To investigate the role of the homocysteine (Hcy) metabolism pathway in hypertension we conducted a case-control association study of Hcy pathway gene variants in a cohort of Caucasian hypertensives and age- and sex-matched normotensives. We genotyped two polymorphisms in the methylenetetrahydrofolate reductase gene (MTHFR C677T and MTHFR A1298C), one polymorphism in the methionine synthase reductase gene (MTRR A66G), and one polymorphism in the methylenetetrahydrofolate dehydrogenase 1 gene (MTHFD1 G1958A) and assessed their association with hypertension using chi-square analysis. We also performed a multifactor dimensionality reduction (MDR) analysis to investigate any potential epistatic interactions among the four polymorphisms and EH. None of the four polymorphisms was significantly associated with EH and although we found a moderate synergistic interaction between MTHFR A1298C and MTRR A66G, the association of the interaction model with EH was not statistically significant (

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Recent evidence indicates that the estrogen receptor-a-negative, androgen receptor (AR)- positive molecular apocrine subtype of breast cancer is driven by AR signaling. The MDA-MB-453 cell line is the prototypical model of this breast cancer subtype; its proliferation is stimulated by androgens such as 5a-dihydrotestosterone (DHT) but inhibited by the progestin medroxyprogesterone acetate (MPA) via AR-mediated mechanisms. We report here that the AR gene in MDAMB- 453 cells contains a G-T transversion in exon 7, resulting in a receptor variant with a glutamine to histidine substitution at amino acid 865 (Q865H) in the ligand binding domain. Compared with wild-type AR, the Q865H variant exhibited reduced sensitivity to DHT and MPA in transactivation assays in MDA-MB-453 and PC-3 cells but did not respond to non-androgenic ligands or receptor antagonists. Ligand binding, molecular modeling, mammalian two-hybrid and immunoblot assays revealed effects of the Q865H mutation on ligand dissociation, AR intramolecular interactions, and receptor stability. Microarray expression profiling demonstrated that DHT and MPA regulate distinct transcriptional programs in MDA-MB-453 cells. Gene Set Enrichment Analysis revealed that DHT- but not MPA-regulated genes were associated with estrogen-responsive transcriptomes from MCF-7 cells and the Wnt signaling pathway. These findings suggest that the divergent proliferative responses of MDA-MB-453 cells to DHT and MPA result from the different genetic programs elicited by these two ligands through the AR-Q865H variant. This work highlights the necessity to characterize additional models of molecular apocrine breast cancer to determine the precise role of AR signaling in this breast cancer subtype. Endocrine-Related Cancer (2012) 19 599–613

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Immune reactions play important roles in determining the in vivo fate of bone substitute materials, either in new bone formation or inflammatory fibrous tissue encapsulation. The paradigm for the development of bone substitute materials has been shifted from inert to immunomodulatory materials, emphasizing the importance of immune cells in the material evaluation. Macrophages, the major effector cells in the immune reaction to implants, are indispensable for osteogenesis and their heterogeneity and plasticity render macrophages a primer target for immune system modulation. However, there are very few reports about the effects of macrophages on biomaterial-regulated osteogenesis. In this study, we used b-tricalcium phosphate (b-TCP) as a model biomaterial to investigate the role of macrophages on the material stimulated osteogenesis. The macrophage phenotype switched to M2 extreme in response to b-TCP extracts, which was related to the activation of calcium-sensing receptor (CaSR) pathway. Bone morphogenetic protein 2 (BMP2) was also significantly upregulated by the b-TCP stimulation, indicating that macrophage may participate in the b-TCP stimulated osteogenesis. Interestingly, when macrophageconditioned b-TCP extracts were applied to bone marrow mesenchymal stem cells (BMSCs), the osteogenic differentiation of BMSCs was significantly enhanced, indicating the important role of macrophages in biomaterial-induced osteogenesis. These findings provided valuable insights into the mechanism of material-stimulated osteogenesis, and a strategy to optimize the evaluation system for the in vitro osteogenesis capacity of bone substitute materials.

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National Australian reviews advocate exploring new models for preservice teacher education. This study investigates the outcomes of the School-Community Integrated Learning (SCIL) pathway as a model for advancing preservice teachers’ understandings of teaching. Thirty-two final-year preservice teachers were surveyed with extended written responses on how the SCIL pathway advanced their understandings of teaching. Results indicated 100% agreement on 6 of the 27 survey items. Indeed, 78% or more preservice teachers agreed that they had a range of experiences across the five categories (i.e., personal-professional skill development, understandings of system requirements, teaching practices, student behaviour and reflective practices). Extended responses suggested they had developed understandings around setting up classrooms, whole school planning processes with professional development, the allocation of teacher responsibilities (e.g., playground duties), parent-teacher interviews, diagnostic testing for literacy and numeracy, commencing running records of students’ assessment results, and the development of relationships (students, teachers and parents). Although a longitudinal study is required to determine long-term effects, the SCIL pathway may be viewed as a positive step towards preparing final-year preservice teachers for their first year as fully-fledged teachers.

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Epithelial-mesenchymal transition (EMT) is a feature of migratory cellular processes in all stages of life, including embryonic development and wound healing. Importantly, EMT features cluster with disease states such as chronic fibrosis and cancer. The dissolution of the E-cadherin-mediated adherens junction (AJ) is a key preliminary step in EMT and may occur early or late in the growing epithelial tumour. This is a first step for tumour cells towards stromal invasion, intravasation, extravasation and distant metastasis. The AJ may be inactivated in EMT by directed E-cadherin cleavage; however, it is increasingly evident that the majority of AJ changes are transcriptional and mediated by an expanding group of transcription factors acting directly or indirectly to repress E-cadherin expression. A review of the current literature has revealed that these factors may regulate each other in a hierarchical pattern where Snail1 (formerly Snail) and Snail2 (formerly Slug) are initially induced, leading to the activation of Zeb family members, TCF3, TCF4, Twist, Goosecoid and FOXC2. Within this general pathway, many inter-regulatory relationships have been defined which may be important in maintaining the EMT phenotype. This may be important given the short half-life of Snail1 protein. We have investigated these inter-regulatory relationships in the mesenchymal breast carcinoma cell line PMC42 (also known as PMC42ET) and its epithelial derivative, PMC42LA. This review also discusses several newly described regulators of E-cadherin repressors including oestrogen receptor-α and new discoveries in hypoxia- and growth factor-induced EMT. Finally, we evaluated how these findings may influence approaches to current cancer treatment.

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Background Current treatment of ovarian cancer patients with chemotherapy leaves behind a residual tumor which results in recurrent ovarian cancer within a short time frame. We have previously demonstrated that a single short-term treatment of ovarian cancer cells with chemotherapy in vitro resulted in a cancer stem cell (CSC)-like enriched residual population which generated significantly greater tumor burden compared to the tumor burden generated by control untreated cells. In this report we looked at the mechanisms of the enrichment of CSC-like residual cells in response to paclitaxel treatment. Methods The mechanism of survival of paclitaxel-treated residual cells at a growth inhibitory concentration of 50% (GI50) was determined on isolated tumor cells from the ascites of recurrent ovarian cancer patients and HEY ovarian cancer cell line by in vitro assays and in a mouse xenograft model. Results Treatment of isolated tumor cells from the ascites of ovarian cancer patients and HEY ovarian cancer cell line with paclitaxel resulted in a CSC-like residual population which coincided with the activation of Janus activated kinase 2 (JAK2) and signal transducer and activation of transcription 3 (STAT3) pathway in paclitaxel surviving cells. Both paclitaxel-induced JAK2/STAT3 activation and CSC-like characteristics were inhibited by a low dose JAK2-specific small molecule inhibitor CYT387 (1 μM) in vitro. Subsequent, in vivo transplantation of paclitaxel and CYT387-treated HEY cells in mice resulted in a significantly reduced tumor burden compared to that seen with paclitaxel only-treated transplanted cells. In vitro analysis of tumor xenografts at protein and mRNA levels demonstrated a loss of CSC-like markers and CA125 expression in paclitaxel and CYT387-treated cell-derived xenografts, compared to paclitaxel only-treated cell-derived xenografts. These results were consistent with significantly reduced activation of JAK2 and STAT3 in paclitaxel and CYT387-treated cell-derived xenografts compared to paclitaxel only-treated cell derived xenografts. Conclusions This proof of principle study demonstrates that inhibition of the JAK2/STAT3 pathway by the addition of CYT387 suppresses the ‘stemness’ profile in chemotherapy-treated residual cells in vitro, which is replicated in vivo, leading to a reduced tumor burden. These findings have important implications for ovarian cancer patients who are treated with taxane and/or platinum-based therapies. Keywords: Ovarian carcinoma, Cancer stem cell, Metastasis, Ascites, Chemoresistance, Recurrence, JAK2/STAT3 pathway