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PURPOSE: The incidence of breast cancer in young women (BCYW) has increased in recent decades. Malignant disease in this subset is characterized by its aggressiveness and poor prognosis. Ovarian function suppression (OFS) in these patients improves survival especially in hormone receptor-positive (HR +) cases. The Regan Composite Risk (RCR) is a prognostic tool to identify high-risk HR + BC candidates for OFS. Our study sought to characterize a Chilean cohort of early HR + BCYW assessing the use of OFS and its related prognosis and the utility of RCR in our patients. METHODS: This was a retrospective population cohort study that included ≤ 35-year-old early HR + /human epidermal growth factor receptor 2 -negative (HER2-) BC patients treated between 2001 and 2021. Analysis included clinical-pathological characteristics, treatment strategies, and survival. Also, we evaluated the association between RCR and survival. RESULTS: A total of 143 patients were included into our study, representing 2.9% of all early BC cases in our registry. Median age was 31 years old (range: 19-35). Most patients (93%) received endocrine therapy (ET). Of these, 18% received OFS. No survival differences were observed among treatment strategies. Median RCR score for patients treated with CT plus ET was significantly higher vs. ET alone (2.95 vs. 1.91; p = 0.0001). Conversely, patients treated with tamoxifen alone had significantly lower RCR scores vs. OFS (2.72 vs. 3.14; p = 0.04). Higher RCR scores were associated with poorer overall survival. CONCLUSION: Less than 20% of very young women with early HR + /HER2-BC in our cohort received OFS, in most cases, this involved surgical oophorectomy. RCR score was higher in patients that underwent CT and OFS and was associated with survival, regardless of treatment. We confirm the RCR score as a valuable prognostic tool to identify high-risk BC patients who could benefit from OFS.
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Neoplasias de la Mama , Femenino , Humanos , Adulto , Neoplasias de la Mama/terapia , Neoplasias de la Mama/tratamiento farmacológico , Antineoplásicos Hormonales/uso terapéutico , Estudios Retrospectivos , Estudios de Cohortes , Quimioterapia Adyuvante , Premenopausia , Receptor ErbB-2/metabolismoRESUMEN
Understanding phenology, its genetics and agronomic consequences, is critical for crop adaptation. Here we aim to (i) characterize lentil response to photoperiod with a focus on five loci: the lentil ELF3 orthologue Sn, two loci linked to clusters of lentil FT orthologues, and two loci without candidates in chromosomes 2 and 5 (Experiment 1: 36 lines, short and long days in a phytotron), and (ii) establish the phenology-yield relationship (Experiment 2: 25 lines, 11 field environments). A vintage perspective, where we quantify time trends in phenotype over three decades of breeding, links both experiments. Yield increased linearly from older to newer varieties at 29 kg ha-1 year-1 or 1.5% year-1, correlated negatively with flowering time in both winter- and summer-rainfall regimes, and decoupled from biomass in favourable environments. Time to flowering shortened from older to newer varieties at -0.56% year-1 in the field, and -0.42% year-1 (short days) and -0.99% year-1 (long days) in the phytotron. Early-flowering lines of diverse origin carried multiple early alleles for the five loci, indicating that at least some of these loci affect phenology additively. Current germplasm primarily features the early-flowering haplotype for an FTb cluster region, hence the potential to increase phenological diversity with yield implications.
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Lens (Planta) , Semillas , Lens (Planta)/genética , Lens (Planta)/crecimiento & desarrollo , Lens (Planta)/fisiología , Semillas/crecimiento & desarrollo , Semillas/genética , Fotoperiodo , Flores/crecimiento & desarrollo , Flores/genética , Estaciones del Año , FenotipoRESUMEN
BACKGROUND: Latin American (LA) studies on triple-negative breast cancer (TNBC) and their characteristics are scarce. This forces physicians to make clinical decisions based on data obtained from studies that include non-Hispanic patients. Our study sought to obtain local epidemiological data, including risk factors and clinical outcomes from a Chilean BC registry. METHODS: This was a retrospective population-cohort study that included patients treated at a community hospital (mid-low income) or an academic private center (high income), in the 2010-2021 period. Univariate and multivariate analyses were performed to identify prognostic factors associated with survival. RESULTS: 647 out of 5,806 BC patients (11.1%) were TNBC. These patients were younger (p = 0.0001) and displayed lower rates of screening-detected cases (p = 0.0001) compared to non-TNBC counterparts. Among TNBC patients, lower income (i. e., receiving treatment at a community hospital) was associated with poorer overall survival (HR: 1.53; p = 0.0001) and poorer BC specific survival (HR: 1.29; p = 0.004). Other risk factors showed no significant differences between TNBC and non-TNBC. As expected, 5-year OS was significantly shorter on TNBC versus non-TNBC patients (p = 0.00001). In our multivariate analyses TNBC subtype (HR: 2.30), locally advanced stage (HR: 7.04 for stage III), lower income (HR: 1.64), or non-screening detected BC (HR: 1.32) were associated with poorer OS. CONCLUSION: To the best of our knowledge, this is the largest LA cohort of TNBC patients. Interestingly, the proportion of TNBC among Chileans was smaller compared to similar studies within LA. As expected, TNBC patients had poorer survival and higher risk for early recurrence versus non-TNBC. Other relevant findings include a higher proportion of premenopausal patients among TNBC. Also, mid/low-income patients that received medical attention at a community hospital displayed lower survival versus private health center counterparts.
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Neoplasias de la Mama , Neoplasias de la Mama Triple Negativas , Humanos , Femenino , Estudios de Cohortes , Estudios Retrospectivos , Neoplasias de la Mama Triple Negativas/epidemiología , Neoplasias de la Mama Triple Negativas/terapia , Neoplasias de la Mama Triple Negativas/diagnóstico , Chile/epidemiología , Factores de Riesgo , PronósticoRESUMEN
BACKGROUND: Insulin resistance (IR) is considered the main driver of obesity related metabolic complications, and is related to oxidative stress and inflammation, which in turn promote each other. There is currently no specific definition of IR in children, rather, that for adult population is used by pediatric endocrinologists instead. Altered insulin secretion dynamics are associated with worse metabolic profiles and type 2 diabetes mellitus development, thus we aimed to test whether insulin response relates to oxidative stress and inflammation in children. METHODS: We conducted a case-control study, including 132 children classified as follows: 33 children without obesity (Lean); 42 with obesity but no IR according to the American Diabetes Association criteria for adults (OBIR-); 25 with obesity and IR and an early insulin response to an oral glucose tolerance test (OGTT) (EP-OBIR +); 32 with obesity, IR, and a late insulin peak (LP-OBIR +); and studied variables associated with lipid and carbohydrate metabolism, oxidative stress, inflammation and inflammasome activation. RESULTS: The measured parameters of children with obesity, IR, and an early insulin response were similar to those of children with obesity but without IR. It was late responders who presented an impaired antioxidant system and elevated oxidative damage in erythrocytes and plasma, and inflammasome activation at their white blood cells, despite lower classical inflammation markers. Increased uric acid levels seems to be one of the underlying mechanisms for inflammasome activation. CONCLUSIONS: It is insulin response to an OGTT that identifies children with obesity suffering oxidative stress and inflammasome activation more specifically. Uric acid could be mediating this pathological inflammatory response by activating NLRP3 in peripheral blood mononuclear cells.
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Diabetes Mellitus Tipo 2 , Resistencia a la Insulina , Niño , Humanos , Estudios de Casos y Controles , Inflamasomas , Inflamación , Insulina , Secreción de Insulina , Leucocitos Mononucleares , Obesidad/complicaciones , Estrés Oxidativo , Ácido ÚricoRESUMEN
In this work, we study a two-dimensional system composed by Active Brownian Particles (ABPs) interacting via a repulsive potential with two length scales-a soft shell and a hard core. Depending on the ratio between the strength of the soft shell barrier and the activity, we find two regimes: If this ratio is much larger or smaller than 1, the observed behavior is comparable with ABPs interacting via a single length scale potential. If this ratio is similar to 1, the two length scales are relevant for both structure and dynamical properties. On the structural side, when the system exhibits a motility induced phase separation, the dense phase is characterized by new and more complex structures compared with the hexatic phase observed in single length scale systems. From the dynamic analysis, we find, to our knowledge, the first manifestation of a dynamic heterogeneity in active particles, reminiscent of the glassy dynamics widely studied in passive colloids.
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OBJECTIVE: Analysis of longitudinal data can provide neonatologists with tools that can help predict clinical deterioration and improve outcomes. The aim of this study is to analyze continuous monitoring data in newborns, using vital signs to develop predictive models for intensive care admission and time to discharge. STUDY DESIGN: We conducted a retrospective cohort study, including term and preterm newborns with respiratory distress patients admitted to the neonatal ward. Clinical and epidemiological data, as well as mean heart rate and saturation, at every minute for the first 12 hours of admission were collected. Multivariate mixed, survival and joint models were developed. RESULTS: A total of 56,377 heart rate and 56,412 oxygen saturation data were analyzed from 80 admitted patients. Of them, 73 were discharged home and 7 required transfer to the intensive care unit (ICU). Longitudinal evolution of heart rate (p < 0.01) and oxygen saturation (p = 0.01) were associated with time to discharge, as well as birth weight (p < 0.01) and type of delivery (p < 0.01). Longitudinal heart rate evolution (p < 0.01) and fraction of inspired oxygen at admission at the ward (p < 0.01) predicted neonatal ICU (NICU) admission. CONCLUSION: Longitudinal evolution of heart rate can help predict time to transfer to intensive care, and both heart rate and oxygen saturation can help predict time to discharge. Analysis of continuous monitoring data in patients admitted to neonatal wards provides useful tools to stratify risks and helps in taking medical decisions. KEY POINTS: · Continuous monitoring of vital signs can help predict and prevent clinical deterioration in neonatal patients.. · In our study, longitudinal analysis of heart rate and oxygen saturation predicted time to discharge and intensive care admission.. · More studies are needed to prospectively prove that these models can helpmake clinical decisions and stratify patients' risks..
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Deterioro Clínico , Enfermedades del Recién Nacido , Síndrome de Dificultad Respiratoria del Recién Nacido , Insuficiencia Respiratoria , Humanos , Recién Nacido , Unidades de Cuidado Intensivo Neonatal , Oximetría , Pronóstico , Estudios RetrospectivosRESUMEN
RATIONALE: Investigations of the isotope ratios of dissolved oxygen (δ18 ODO ) provide valuable information about the oxygen cycle in aquatic systems. However, oxidation of Fe(II) may change pristine δ18 ODO values during storage and can lead to a misinterpretation. We sampled an Fe(II)-rich spring system and measured δ18 ODO values at various time intervals in order to determine influences of Fe-oxidation. METHODS: Water samples were collected from an Fe-rich spring and related stream and the δ18 ODO values were measured in fresh, 4- and 13-day-old samples with an isotope ratio mass spectrometer. Three replicates were measured for each sample with a 1σ of ± 0.2. On-site parameters and Fe(II) contents were also measured over the course of the spring system by multi-parameter probes and spectrophotometry. RESULTS: The δ18 ODO values over the course of the spring system in fresh, 4- and 13-day-old samples revealed differences of up to 8. We explain this increase by the consumption of DO by Fe(II)-oxidation. After a flow length of 85 m the differences in δ18 ODO values between fresh and older samples decreased because most of the Fe(II) was consumed. CONCLUSIONS: False interpretations of δ18 ODO values are possible if Fe-rich water samples are measured after too long storage, and we recommend measurement immediately after sampling.
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BACKGROUND: Blood biochemistry and reference intervals help to differentiate between healthy and ill dogs as well as to provide information for the prognosis, evaluation, and monitoring; however, these intervals are often obtained from adult animals. It is essential to understand that puppies and adults are physiologically different, which justifies the need to obtain age-specific biochemical reference intervals. The aim of this research was to assess the potential effect of age, sex, body size, and their interaction on routine biochemical analytes and physiological constants (body temperature, heart rate, and respiratory rate). To carry out the research, we selected 197 healthy dogs of both sexes and different body sizes (small, medium and large) classified by age: group I (4-8 wk), group II (9-24 wk), group III (25-52 wk), and group IV (> 52 wk). The biochemical analysis included the measurement of the enzymatic activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and the concentrations of cholesterol, triglycerides, total proteins, albumin, globulins, glucose, urea, and creatinine. Statistical analyses used analysis of variance (ANOVA) and a general linear model (GLM), which allows the comparison of multiple factors at two or more levels (p < 0.05). RESULTS: The results of this study showed that ALT, total protein, albumin, globulin, urea, creatinine, and body temperature levels were lower in puppies than in adult dogs of group IV (p < 0.05), while the enzymatic activity of ALP, LDH, glucose concentration, and heart rate were higher. Whereas sex, body size and the interaction did not show a significant effect (p > 0.05). CONCLUSIONS: Some biochemical components are influenced by age. For this reason, this manuscript contributes with additional data for the clinical interpretation of blood biochemical results in puppies.
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Envejecimiento/fisiología , Análisis Químico de la Sangre/veterinaria , Tamaño Corporal/fisiología , Perros/sangre , Envejecimiento/sangre , Animales , Perros/crecimiento & desarrollo , Perros/fisiología , Femenino , Pruebas Hematológicas/veterinaria , Masculino , Valores de ReferenciaRESUMEN
We study a two-dimensional system composed by Active Brownian Particles (ABPs), focusing on the onset of Motility Induced Phase Separation (MIPS), by means of molecular dynamics simulations. For a pure hard-disk system with no translational diffusion, the phase diagram would be completely determined by their density and Péclet number. In our model, two additional effects are present: translational noise and the overlap of particles; we study the effects of both in the phase space. As we show, the second effect can be mitigated if we use, instead of the standard Weeks-Chandler-Andersen potential, a stiffer potential: the pseudo-hard sphere potential. Moreover, in determining the boundary of our phase space, we explore different approaches to detect MIPS and conclude that observing dynamical features, via the non-Gaussian parameter, is more efficient than observing structural ones, such as through the local density distribution function. We also demonstrate that the Vogel-Fulcher equation successfully reproduces the decay of the diffusion as a function of density, with the exception of very high densities. Thus, in this regard, the ABP system behaves similar to a fragile glass.
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BACKGROUND: Prostate cancer is one of the most frequently diagnosed types of cancers worldwide. In its initial period, the tumor is hormone-sensitive, but in advanced states, it evolves into a metastatic castration-resistant tumor. In this state, chemotherapy with taxanes such as Docetaxel (DTX) comprises the first line of treatment. However, the response is poor due to chemoresistance and toxicity. On the other hand, Pentoxifylline (PTX) is an unspecific inhibitor of phosphodiesterases; experimental, and clinically it has been described as sensitizing tumor cells to chemotherapy, increasing apoptosis and decreasing senescence. We study whether the PTX sensitizes prostate cancer cells to DTX for greater effectiveness. METHODS: PC3 human prostate cancer cells were treated in vitro at different doses and times with PTX, DTX, or their combination. Viability was determined by the WST-1 assay by spectrophotometry, cell cycle progression, apoptosis, generic caspase activation and senescence by flow cytometry, DNA fragmentation and caspases-3, -8, and -9 activity by ELISA. RESULTS: We found that PTX in PC3 human prostate cancer cells induces significant apoptosis per se and increases that generated by DTX, while at the same time it reduces the senescence caused by the chemotherapy and increases caspases-3,-8, and -9 activity in PTX + DTX-treated cells. Both treatments blocked the PC3 cell in the G1 phase. CONCLUSIONS: Our results show that PTX sensitizes prostate tumor cells to apoptosis induced by DTX. Taken together, the results support the concept of chemotherapy with rational molecular bases.
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Antineoplásicos/farmacología , Docetaxel/farmacología , Pentoxifilina/farmacología , Inhibidores de Fosfodiesterasa/farmacología , Neoplasias de la Próstata/patología , Humanos , Masculino , Células PC-3/efectos de los fármacosRESUMEN
Asymmetric obstacles can be exploited to direct the motion and induce sorting of run-and-tumble particles. In this work, we show that flocking particles which follow the Vicsek model aligning rules experience collective trapping in the presence of a wall of funnels made of chevrons, concentrating at the opposite side of the wall of funnels to run-and-tumble particles. Flocking particles can be completely trapped or exhibit a dynamical trapping behaviour; these two regimes open the door to the design of a system with two perpendicular flows of active particles. This systematic study broadens our understanding of the emergence of collective motion of microorganisms in confined environments and directs the design of new microfluidic devices able to control these collective behaviours.
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In this work we have characterized the phase behaviour and the dynamics of bidimensional mixtures of active and passive Brownian particles. We have evaluated state diagrams at several concentrations of the passive components finding that, while passive agents tend to hinder phase separation, active agents force crystal-like structures on passive colloids. In order to study how passive particles affect the dynamics of the mixture, we have computed the long-time diffusion coefficient of each species, concluding that active particles induce activity and super-diffusive behaviour on passive ones. Interestingly, at the density at which the system enters a MIPS state the active particles' diffusivity shows an inflection point and the passive particles' one goes through a maximum, due to the change in the dynamics of the active components, as shown in the displacement's probability distribution function.
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Introduction Posttraumatic brachial plexus injuries are devastating, as the brain and spinal cord are disconnected from the upper limb. Restoration of elbow flexion has been widely recognized as the primary objective of nerve reconstruction. In the absence of utilizable (ruptured) root stumps in the neck, one has recourse only to nerve transfers. The direct transfer of intercostal nerves to the musculocutaneous nerve is one of the techniques that has been commonly employed over the past four decades. However, the outcomes of this procedure cited in the literature have varied considerably. The patient's age and the delay from the accident to surgery have been known to affect the results of nerve reconstruction operations. The authors present a study of the effect of these parameters on intercostal nerve transfers. Methods The data of 232 patients with total and near-total brachial plexus injuries treated by the senior author between April 1995 and December 2015 was examined. Intercostal nerve transfers were used for the restoration of biceps function in each of these patients. The outcomes were tabulated, and the correlation with the age and the delay before surgery was examined. Results The strength of the biceps regained was better in patients younger than 30 years old and those operated upon earlier than 6 months from the accident. The differences in outcomes were found to be statistically significant ( p = 0.001 for preoperative delay and p < 0.005 for the patient's age). Conclusion The results give clear proof of the significant effect of the age and preoperative delay on the outcomes of intercostal nerve transfers for restoration of biceps function. These findings can serve as pointers to help the surgeon in choosing the method of nerve reconstruction in a given case.
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In our work we have studied a two-dimensional suspension of finite-size Vicsek hard disks, whose time evolution follows an event-driven dynamics between subsequent time steps. Having compared its collective behaviour with the one expected for a system of scalar Vicsek point-like particles, we have analysed the effect of considering two possible bouncing rules between the disks: a Vicsek-like rule and a pseudo-elastic one, focusing on the order-disorder transition. Next, we have added to the two-dimensional suspension of hard-disk Vicsek particles disk-like passive obstacles of two types: either fixed in space or moving according to the same event-driven dynamics. We have performed a detailed analysis of the particles' collective behaviour observed for both fixed and moving obstacles. In the fixed obstacles case, we have observed formation of clusters at low noise, in agreement with previous studies. When using moving passive obstacles, we found that that order of active particles is better destroyed as the drag of obstacles increases. In the no drag limit an interesting result was found: introduction of low drag passive particles can lead in some cases to a more ordered state of active flocking particles than what they show in bulk.
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Residential solid fuel combustion in cookstoves has established health impacts including bladder and lung cancers, cataracts, low birth weight, and pneumonia. The chemical composition of particulate matter (PM) from 4 commonly-used solid fuels (coal, dung, ambient/dry applewood, and oakwood pellets), emitted from a gasifier cookstove, as well as propane, were examined. Temporal changes between the different cookstove burn-phases were also explored. Normalized concentrations of non-refractory PM1, total organics, chloride, ammonium, nitrate, sulfate, and 41 particle-phase polycyclic aromatic hydrocarbons (PAHs) were measured using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a Thermal desorption Aerosol Gas chromatograph (TAG), respectively. Coal demonstrated the highest fraction of organic matter in its particulate emission composition (98%), followed by dung (94%). Coal and dung also demonstrated the highest numbers and concentrations of PAHs. While dry applewood emitted ten times lower organic matter compared to ambient applewood, a higher fraction of these organics was composed of PAHs, especially the more toxic ones such as benzo(a)pyrene (9.63ng/L versus 0.04ng/L), and benzo(b)fluoranthene (31.32ng/L versus 0.19ng/L). Data from the AMS demonstrated no clear trends for any of the combustion fuels over the different combustion phases unlike the previously reported trends observed for the physical characteristics. Of the solid fuels, pellets demonstrated the lowest emissions. Emissions from propane were below the quantification limit of the instruments. This work highlights the benefits of incorporating additional metrics into the cookstove evaluation process, thus enriching the existing PM data inventory.
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Contaminantes Atmosféricos/química , Contaminación del Aire Interior/análisis , Monitoreo del Ambiente , Compuestos Inorgánicos/análisis , Compuestos Orgánicos/análisis , Material Particulado/química , Contaminantes Atmosféricos/análisis , Carbón Mineral , Culinaria , Heces , Material Particulado/análisis , MaderaRESUMEN
Volume-to-surface area ratio (V:S) across stem succulent taxa varies by almost two orders of magnitude. The broad range in V:S of cacti and other succulent species likely has considerable importance for adaptation since stem volume determines the storage capacity of water, carbon and nutrients and stem surface area is directly related to whole-stem photosynthetic capacity. We examined the intrinsic physiological tradeoffs across diverse stem morphologies in three divergent evolutionary groups where stem succulence is common: Cactoideae, Opuntioideae (Cactaceae) and Euphorbiaceae. We predicted that variation in physiological response to environmental conditions would be (1) constrained by stem V:S, and (2) detectable in the stable isotope ratios of plant tissues. Stable isotope ratios were measured in the spines/prickles of 62 stem-succulent species occurring in a common garden setting in Phoenix, AZ, USA. Biomass δ(13)C, δ(2)H and δ(18)O increased with V:S in Cactoideae only, possibly reflecting various levels of Crassulacean acid metabolism (CAM) strength in the other lineages. Within Cactoideae-group with the highest CAM strength and largest range in V:S-δ(13)C and δ(18)O increased 2.2 and 11.5 , respectively, with a 22-fold increase in V:S. Both δ(13)C and V:S decreased with species climate-niche estimates of precipitation, indicating that stem morphology and physiology in Cactoideae may be constrained by available moisture. Taken together, these data suggest that physiological tradeoffs associated with stem V:S are detectable across broad evolutionary groups despite differences in CAM strength.
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Fotosíntesis , Tallos de la Planta/química , Cactaceae , Isótopos de Carbono , Clima , IsótoposRESUMEN
INTRODUCTION: Papillary thyroid carcinoma (PTC) is a rare childhood disease. The development of PTC in dyshormonogenetic congenital hypothyroidism (CH) is infrequent, with very few case reports in literature. OBJECTIVE: To report a case of PTC in a boy with dyshormonogenetic CH without goitre and exposed to ionising radiation. To evaluate relationships between these factors and development of PTC. CASE REPORT: We present a boy with dyshormonogenetic CH since birth. Early hormonal substitution was initiated, with subsequent normal levels of thyrotropin and thyroid hormones. He has also congenital cardiomyopathy, exposed to interventional treatment with 10 heart catheterisations, and approximately 26 chest X-rays at paediatric doses. A thyroid nodule was found in thyroid echography at the age of 6 years old. Fine needle aspiration biopsy confirmed high probability of thyroid carcinoma (Bethesda 5). The pre-surgical thorax and cerebral scan showed no evidence of metastasis. The patient underwent total thyroidectomy. Pathological examination revealed a 0.5cm papillary thyroid micro-carcinoma in the right lobe, with no evidence of dissemination. CONCLUSION: Genetic mutations and radiation exposure may play an important role in the development of PTC. There may be common pathways between dyshormonogenetic CH and thyroid carcinoma that need further investigation.
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Carcinoma/etiología , Hipotiroidismo Congénito/complicaciones , Neoplasias de la Tiroides/etiología , Tiroidectomía/métodos , Biopsia con Aguja Fina , Carcinoma/diagnóstico , Carcinoma/cirugía , Carcinoma Papilar , Niño , Hipotiroidismo Congénito/terapia , Humanos , Masculino , Cáncer Papilar Tiroideo , Hormonas Tiroideas/administración & dosificación , Neoplasias de la Tiroides/diagnóstico , Neoplasias de la Tiroides/cirugíaRESUMEN
INTRODUCTION: Electronic cigarettes (e-cigs) generate aerosols that users inhale. Analyses of e-liquids inconsistently report nicotyrine, a nicotine analog that could impede nicotine metabolism, raising questions about nicotyrine formation. METHODS: E-cig aerosols were analyzed on-line using a Thermal Desorption Aerosol Gas Chromatograph. Three e-liquids were tested: an unflavored solution in propylene glycol (PG); an unflavored solution in PG and vegetable glycerin (VG), and a flavored solution in PG and VG. A heating duration experiment determined the nicotyrine to nicotine ratio (NNR) in particle phase as a function of the duration of e-cig activation. An aging experiment determined the NNR in e-liquids and aerosols as a function of time since initial exposure to air and storage condition. RESULTS: Nicotine and nicotyrine were quantified in all 3 e-liquids and aerosols. Duration of e-cig activation was inversely related to NNR (NNR = 0.04 with 3-s activation, 0.26 with 0.5 s). Aging influenced both e-liquid NNR and aerosol NNR. On average, the e-liquid NNR increased from 0.03 at 11 days after opening to 0.08 after 60 days. For similar heating durations, aerosol NNR increased from 0.05 at 11 days to 0.23 after 60 days. Storage conditions had little effect on NNR. CONCLUSIONS: E-cig aerosols have variable nicotyrine quantities. Aerosol NNR depends on vaping technique and time elapsed since the e-liquid was exposed to air. It is hypothesized that aerosolized nicotyrine could facilitate nicotine absorption, inhibit the metabolism of nicotine, and reduce a user's urge to smoke.