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Ono K, Takahashi R, Morita K, Ara Y, Abe S, Ito S, Uno S, Abe M, Shirasaka T. Can AI predict walking independence in patients with stroke upon admission to a recovery-phase rehabilitation ward? Jpn J Compr Rehabil Sci 2024; 15: 1-7. Objective: This study aimed to develop a prediction model for walking independence in patients with stroke in the recovery phase at the time of hospital discharge using Prediction One, an artificial intelligence (AI)-based predictive analysis tool, and to examine its utility. Methods: Prediction One was used to develop a prediction model for walking independence for 280 patients with stroke admitted to a rehabilitation ward-based on physical and mental function information at admission. In 134 patients with stroke hospitalized during different periods, accuracy was confirmed by calculating the correct response rate, sensitivity, specificity, and positive and negative predictive values based on the results of AI-based predictions and actual results. Results: The prediction accuracy (area under the curve, AUC) of the proposed model was 91.7%. The correct response rate was 79.9%, sensitivity was 95.7%, specificity was 62.5%, positive predictive value was 73.6%, and negative predictive value was 93.5%. Conclusion: The accuracy of the prediction model developed in this study is not inferior to that of previous studies, and the simplicity of the model makes it highly practical.
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INTRODUCTION: Peritoneal dialysis (PD) is a mode of therapy in which the patients themselves actively participate in the care of their own disease. We examined a possible association of salt reduction before starting dialysis with PD technique survival. METHODS: This retrospective cohort study included 42 patients who started PD between April 2014 and March 2018. Participants were allocated to two groups based on their estimated daily salt intake before the initiation of dialysis: patients with an estimated daily salt intake <6 g/day were allocated to the appropriate salt intake group (AS group), while the rest were assigned to the high salt intake group (HS group). RESULTS: During a median follow-up of 47 months, PD technique survival, defined by death or transition to hemodialysis, was significantly lower in the HS group compared to the AS group. CONCLUSION: Successful salt reduction before dialysis introduction is associated with better PD technique survival.
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Diálisis Peritoneal , Humanos , Diálisis Peritoneal/métodos , Masculino , Femenino , Estudios Retrospectivos , Persona de Mediana Edad , Anciano , Cloruro de Sodio Dietético/administración & dosificación , Fallo Renal Crónico/terapia , Fallo Renal Crónico/mortalidad , Adhesión a Directriz/estadística & datos numéricos , Estudios de Cohortes , Educación del Paciente como Asunto/métodos , Guías de Práctica Clínica como AsuntoRESUMEN
Objectives: Assuming SpA manifestations may vary among patients with different inflammatory bowel disease (IBD) subtypes, we explored the clinical characteristics associated with the presence of Crohn's disease (CD) or ulcerative colitis (UC) in patients with spondyloarthritis (SpA). Methods: We included 3152 patients of ASAS-PerSpA study diagnosed with either axial SpA or peripheral SpA, according to their treating rheumatologist. Of these, 146 (4.6%) had confirmed IBD by endoscopy and were categorized into CD or UC groups. Demographics, clinical characteristics, treatments and patient-reported outcomes were compared between the two subgroups. Results: From 146 patients included in the current analysis, 87 (59.6%) had CD [75 (86.2%) axial SpA and 12 (13.8%) peripheral SpA], and 39 (26.7%) had UC [34 (87.2%) axial SpA and 5 (12.8%) peripheral SpA]. CD and UC groups had similar age with average of 44.9 (13.5) vs 44.0 (13.0) years, respectively, and a slight male predominance in CD (63.2%) compared with UC (51.3%). Diagnostic delay for SpA was 7.0 (6.9) years for CD and 8.8 (8.1) years for UC. Chronic back pain was the most reported symptom present in 95.4% of CD patients and 89.7% of UC patients. Both groups had similar musculoskeletal phenotyping, with higher frequency of psoriasis (15.4%) and uveitis 28.2% in UC; and higher tendency to be HLA-B27 positive in CD (51.9% in CD vs.s 39.4% in UC). Conclusion: In our analysis patients with SpA and concurrent CD or UC had mainly similar musculoskeletal phenotypes. However, they differ slightly in extra-musculoskeletal manifestations and HLA-B27 prevalence.
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The lowland tropical triple-cropping rice system has unique characteristics that affect the hydrological, nutrient, and atmospheric environments. To better understand the ecosystem carbon and water dynamics of a triple-cropping rice paddy from the perspective of sustainability, ecosystem-level CO2 flux and ecosystem water use efficiency (eWUE) were observed using eddy covariance over 2 years (2016-2018) at an experimental field site in southern India, and gross primary production (GPP) and ecosystem respiration (RE) were derived using the flux partitioning technique. Results showed that among the three crop seasons per year, GPP and RE were higher (887.2 and 570.2 g C m-2, respectively) in Thaladi (October-January: wet season) than in Kuruvai (June-September: dry season; 773.4 and 568.9 g C m-2, respectively) and summer rice (February-May; 694.0 and 499.7 g C m-2, respectively) owing to the longer growing season. Triple-cropping meant that the quasi-annual GPP of 2598 g C m-2 (i.e., the total value for the three consecutive seasons, including the corresponding fallow periods) was much greater than the quasi-annual RE of 1974 g C m-2. Consequently, the net ecosystem production value was positive (624 g C m-2). Evapotranspiration was also high on the annual scale (1681 mm); that is, 48 % greater than mean annual precipitation (1139 mm). Analysis revealed that Thaladi had higher eWUE (2.21 g C (kg H2O)-1) than that of Kuruvai (1.46 g C (kg H2O)-1) and summer rice (1.57 g C (kg H2O)-1) owing to decreased water loss in cloudy weather. Intense solar radiation is generally recognized as advantageous for crop growth in most regions, but not for Kuruvai and summer rice, when too strong solar radiation increases loss of water unused for photosynthesis. The findings indicate that water-saving techniques should be targeted on the Kuruvai and summer rice seasons.
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Currently, tongue cancers are primarily managed by surgery, and interstitial brachytherapy is only recommended for a selected group of early state T1-2N0 patients who refuse surgery or are medically inoperable. In this report, a case with T3N2cM0 tongue cancer who has been effectively treated by the combination of concurrent chemoradiotherapy involving volumetric arc therapy and boost high-dose rate interstitial brachytherapy is presented. Of course, surgery remains the main treatment strategy for tongue cancer patients; however, the authors believe that if volumetric arc therapy is carefully planned to reduce the mandible dose as much as possible and high-dose rate interstitial brachytherapy with a mouthpiece that protects the mandible is combined, it is possible to treat T3N2 disease, and this can be considered for patients who want to preserve organ function.
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Braquiterapia , Neoplasias de la Lengua , Humanos , Braquiterapia/efectos adversos , Neoplasias de la Lengua/radioterapia , Dosificación Radioterapéutica , Cabeza , QuimioradioterapiaRESUMEN
There are particularly few reports on kidney transplantation after hematopoietic stem cell transplantation (HSCT) for malignant lymphoma, and none of the cases reported a favorable outcome in patients who received kidney transplantation from a different donor to HSCT. In this report, we describe the first case of kidney transplantation from a different donor to HSCT with a successful outcome. Furthermore, we reviewed the previously reported cases. A 59-year-old female patient received an HSCT from her younger brother after chemotherapy for malignant lymphoma. After HSCT, she did not have graft-versus-host disease (GVHD) requiring maintenance treatment. The patient developed chronic kidney disease requiring kidney replacement therapy, probably due to drug toxicity or cardio-renal syndrome. At age 65, she underwent an ABO-compatible, HLA-A, -B, -DR 5/6 mismatched kidney transplantation from her husband. Immunosuppressive therapy with tacrolimus, mycophenolate mofetil, methylprednisolone, and basiliximab was administered. The patient had urinary tract infections at 7 days, 9 weeks, and 4 months after kidney transplantation, and cytomegalovirus antigenemia at 9 weeks after kidney transplantation, which improved with antibiotic and valganciclovir, respectively. When each infection occurred, we weakened immunosuppressive therapy. Four years after kidney transplantation, the patient is in good clinical condition with a serum creatinine of 1.2 mg/dL, without critical infection or malignancy. In this case, we believe that it was important to optimize the immunosuppressive therapy. In addition, from a review of previous cases, it seemed important that there was no GVHD requiring maintenance therapy in order to prevent excessive immunosuppression.
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Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas , Linfoma , Anciano , Antibacterianos/uso terapéutico , Basiliximab , Creatinina , Femenino , Enfermedad Injerto contra Huésped/etiología , Antígenos HLA-A , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Humanos , Inmunosupresores/efectos adversos , Riñón , Linfoma/etiología , Masculino , Metilprednisolona , Persona de Mediana Edad , Ácido Micofenólico/uso terapéutico , Tacrolimus , ValganciclovirRESUMEN
The purpose of this study was to clarify the clinical characteristics of spondyloarthritis (SpA) patients with inflammatory bowel disease (IBD) compared to those without IBD. Furthermore, among patients with SpA and IBD, we aimed to clarify what clinical characteristics lead rheumatologists to diagnose "IBD-related arthritis." Utilizing SpA and psoriatic arthritis (PsA) patients' data from an international, cross-sectional, observational study, we analyzed information on demographics and disease characteristics, dichotomizing patients by IBD status. The presence or absence of IBD was determined based on data collection of treating rheumatologists. Patients with SpA (including PsA) and IBD were also categorized based on treating rheumatologists' definitive diagnosis in regard to SpA type, and compared by whether the patients had IBD-related arthritis or not. Among 4465 SpA patients, 287 (6.4%, 95%CI 5.7-7.2%) were identified with IBD. Compared to SpA patients without IBD, patients with SpA and IBD had a longer diagnostic delay (5.1 vs. 2.9 years, p < 0.001). In patients with SpA and IBD, 111 (38.7%, 95%CI 33.0-44.6%) were diagnosed with IBD-related arthritis. Multivariable analyses showed that HLA-B27 positivity [OR = 0.35, (95%CI 0.15-0.80)], psoriasis [OR = 0.14, (95%CI 0.04-0.50)], IBD as first symptom of SpA [OR = 3.32, (95%CI 1.84-6.01)], and need for IBD-specific treatment [OR = 5.41, (95%CI 2.02-14.50)] were independently associated with the definitive diagnosis of IBD-related arthritis. Collaboration with gastroenterologists is needed to shorten the diagnostic delay in patients with SpA and IBD. The recognition of the factors for the diagnosis of "IBD-related arthritis" may lead to the elucidation of the pathogenesis.
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Artritis Psoriásica , Enfermedades Inflamatorias del Intestino , Espondiloartritis , Artritis Psoriásica/complicaciones , Artritis Psoriásica/diagnóstico , Artritis Psoriásica/epidemiología , Estudios Transversales , Diagnóstico Tardío , Humanos , Enfermedades Inflamatorias del Intestino/complicaciones , Enfermedades Inflamatorias del Intestino/diagnóstico , Enfermedades Inflamatorias del Intestino/epidemiología , Espondiloartritis/complicaciones , Espondiloartritis/diagnóstico , Espondiloartritis/epidemiologíaRESUMEN
OBJECTIVES: To delineate characteristics of non-radiographic axial spondyloarthritis (nr-axSpA) in Asia versus non-Asian regions, and compare radiographic axSpA (r-axSpA) with nr-axSpA within Asia. METHODS: Data were collected from the Assessment of SpondyloArthritis international Society-COMOrbidities in SPondyloArthritis database. Categorising patients by region, we compared clinical characteristics between nr-axSpA from Asia vs elsewhere (Europe, the Americas and Africa). Within Asians, we additionally compared patient characteristics of those with nr-axSpA versus r-axSpA. RESULTS: Among 3984 SpA cases, 1094 were from Asian countries. Of 780 axSpA patients in Asia, 112 (14.4%) had nr-axSpA, less than in non-Asian countries (486/1997, 24.3%). Nr-axSpA patients in Asia were predominantly male (75.9% vs 47.1%), younger at onset (22.8 vs 27.8 years) and diagnosis (27.2 vs 34.5 years), and experienced less diagnostic delay (1.9 vs 2.9 years) compared with nr-axSpA in non-Asian countries. Nr-axSpA in Asia exhibited higher human leucocyte antigens-B27 prevalence (90.6% vs 61.9%), fewer peripheral SpA features (53.6% vs 66.3%) and similar extra-articular and comorbid disease rates compared with those with nr-axSpA in non-Asian countries. Disease activity, functional impairment and MRI sacroiliitis were less in nr-axSpA in Asia, with higher rates of non-steroidal anti-inflammatory drug response and less methotrexate and biological disease-modifying antirheumatic drugs use. Within Asia, r-axSpA showed higher disease activity and structural damage compared with nr-axSpA, with no differences in other features. CONCLUSION: Among axSpA, lower frequency of nr-axSpA was observed in Asia. Our results offer an opportunity to better understand clinical characteristics and optimise diagnostic strategies, such as ensuring access and availability of MRI resources for accurate diagnosis of nr-axSpA in Asia.
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Espondiloartritis , Espondilitis Anquilosante , Asia/epidemiología , Estudios Transversales , Diagnóstico Tardío , Humanos , Masculino , Espondiloartritis/diagnóstico por imagen , Espondiloartritis/epidemiología , Estados UnidosRESUMEN
While wetlands are the largest natural source of methane (CH4 ) to the atmosphere, they represent a large source of uncertainty in the global CH4 budget due to the complex biogeochemical controls on CH4 dynamics. Here we present, to our knowledge, the first multi-site synthesis of how predictors of CH4 fluxes (FCH4) in freshwater wetlands vary across wetland types at diel, multiday (synoptic), and seasonal time scales. We used several statistical approaches (correlation analysis, generalized additive modeling, mutual information, and random forests) in a wavelet-based multi-resolution framework to assess the importance of environmental predictors, nonlinearities and lags on FCH4 across 23 eddy covariance sites. Seasonally, soil and air temperature were dominant predictors of FCH4 at sites with smaller seasonal variation in water table depth (WTD). In contrast, WTD was the dominant predictor for wetlands with smaller variations in temperature (e.g., seasonal tropical/subtropical wetlands). Changes in seasonal FCH4 lagged fluctuations in WTD by ~17 ± 11 days, and lagged air and soil temperature by median values of 8 ± 16 and 5 ± 15 days, respectively. Temperature and WTD were also dominant predictors at the multiday scale. Atmospheric pressure (PA) was another important multiday scale predictor for peat-dominated sites, with drops in PA coinciding with synchronous releases of CH4 . At the diel scale, synchronous relationships with latent heat flux and vapor pressure deficit suggest that physical processes controlling evaporation and boundary layer mixing exert similar controls on CH4 volatilization, and suggest the influence of pressurized ventilation in aerenchymatous vegetation. In addition, 1- to 4-h lagged relationships with ecosystem photosynthesis indicate recent carbon substrates, such as root exudates, may also control FCH4. By addressing issues of scale, asynchrony, and nonlinearity, this work improves understanding of the predictors and timing of wetland FCH4 that can inform future studies and models, and help constrain wetland CH4 emissions.
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Metano , Humedales , Dióxido de Carbono , Ecosistema , Agua Dulce , Estaciones del AñoRESUMEN
INTRODUCTIONS: The morbidity and mortality after completion pneumonectomy (CP) are reportedly high. We, herein, report the outcomes of CP at our institution. SUBJECTS: Nine consecutive patients [7 men and 2 women, average age of 72 years(range 44~84 years)] who underwent CP for recurrence of lung cancer during 2012~2018 were retrospectively reviewed. RESULTS: Right-sided sleeve CP was performed in two cases and left-sided CP in seven cases. The indications for surgery were lymph node metastasis of the cancer, pulmonary metastasis, and bronchial stump recurrence in 4, 3, and 2 cases, respectively. Postoperative complications occurred in six patients. One of the patients who underwent right sleeve pneumonectomy developed bronchopleural fistula and died 68 days after the surgery. The mean follow-up period was 33 months, and four patients died during follow-up. Of the 5 patients still alive, 4 had no recurrence and 1 had recurrence in the stump of the main bronchus. The five-year overall survival rate was 78%. CONCLUSIONS: Although only few cases were assessed, the prognosis after CP at our institution was relatively good.
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Fístula Bronquial , Neoplasias Pulmonares , Enfermedades Pleurales , Adulto , Fístula Bronquial/cirugía , Femenino , Humanos , Neoplasias Pulmonares/cirugía , Masculino , Recurrencia Local de Neoplasia/cirugía , Enfermedades Pleurales/cirugía , Neumonectomía , Complicaciones Posoperatorias/cirugía , Estudios RetrospectivosRESUMEN
Reactive arthritis (ReA) is typically preceded by sexually transmitted disease or gastrointestinal infection. An association has also been reported with bacterial and viral respiratory infections. Herein, we report the first case of ReA after the he severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This male patient is in his 50s who was admitted with COVID-19 pneumonia. On the second day of admission, SARS-CoV-2 PCR was positive from nasopharyngeal swab specimen. Despite starting standard dose of favipiravir, his respiratory condition deteriorated during hospitalisation. On the fourth hospital day, he developed acute respiratory distress syndrome and was intubated. On day 11, he was successfully extubated, subsequently completing a 14-day course of favipiravir. On day 21, 1 day after starting physical therapy, he developed acute bilateral arthritis in his ankles, with mild enthesitis in his right Achilles tendon, without rash, conjunctivitis, or preceding diarrhoea or urethritis. Arthrocentesis of his left ankle revealed mild inflammatory fluid without monosodium urate or calcium pyrophosphate crystals. Culture of synovial fluid was negative. Plain X-rays of his ankles and feet showed no erosive changes or enthesophytes. Tests for syphilis, HIV, anti-streptolysin O (ASO), Mycoplasma, Chlamydia pneumoniae, antinuclear antibody, rheumatoid factor, anticyclic citrullinated peptide antibody and Human Leukocyte Antigen-B27 (HLA-B27) were negative. Gonococcal and Chlamydia trachomatis urine PCR were also negative. He was diagnosed with ReA. Nonsteroidal Anti-Inflammatory Drug (NSAID)s and intra-articular corticosteroid injection resulted in moderate improvement.
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Articulación del Tobillo/diagnóstico por imagen , Artritis Reactiva/diagnóstico , Infecciones por Coronavirus/terapia , Neumonía Viral/terapia , Síndrome de Dificultad Respiratoria/terapia , Corticoesteroides/uso terapéutico , Amidas/uso terapéutico , Antiinflamatorios no Esteroideos/uso terapéutico , Antivirales/uso terapéutico , Artritis Reactiva/tratamiento farmacológico , Artritis Reactiva/etiología , Artrocentesis , Betacoronavirus , COVID-19 , Infecciones por Coronavirus/complicaciones , Humanos , Inyecciones Intraarticulares , Masculino , Persona de Mediana Edad , Pandemias , Neumonía Viral/complicaciones , Prohibitinas , Pirazinas/uso terapéutico , Respiración Artificial , Síndrome de Dificultad Respiratoria/complicaciones , SARS-CoV-2RESUMEN
Dental treatment improves the experience of eating by healing illnesses in the oral cavity or through the installation of special devices. However, mastication can often prove difficult for short periods of time after dental treatment, potentially limiting the types of food that can be consumed. Therefore, we proposed a highly nutritious meal strategy for dental outpatients (hereafter, "easy-to-eat meals"). We previously reported patients' subjective assessment of these easy-to-eat meals as determined through a questionnaire survey. The purpose of the present study was to investigate how differences in age affected such assessments. The study participants comprised patients scheduled to undergo dental treatment. They were divided into 2 groups: one of patients aged above and one of those aged below 70 years. All were required to consume provided easy-to-eat meals at the dental hospital directly after treatment and then answer a questionnaire. The questionnaire included items on patient satisfaction with the meals, taste, portion size, convenience, reduction in discomfort, and whether they would consume them again. The format of the questionnaire was a visual analog scale (VAS), ranging from 0 (negative) to 10 (positive). Portion size was to be rated on a scale from 0 ("Not enough") to 10 ("Too much"), with 5 being "Just right". Correlations between the questionnaire items were investigated to determine how they influenced each other. The VAS average for "Reduction in discomfort" was 8.45±1.39 in the non-elderly group and 6.07±2.92 in the elderly group, and the difference was significant (p=0.02); the VAS average for "Taste" was 6.49±2.32 in the non-elderly group and 4.91±0.98 in the elderly group, and the difference was significant (p=0.04). The results of this study suggest that providing such meal plans as nutritional guidance after dental treatment can influence quality of life in elderly patients.
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Pacientes Ambulatorios , Calidad de Vida , Anciano , Humanos , Masticación , Comidas , Persona de Mediana Edad , Encuestas y CuestionariosRESUMEN
MAIN CONCLUSION: A hypothesis that squalene cyclase genes are widely distributed throughout ferns was proposed. We successfully isolated a squalene cyclase pseudogene from a fern from which no triterpene hydrocarbons were detected Ferns are the most primitive vascular plants, with their locations ranging from tropical to cold temperate regions and from lowland to alpine zones. The triterpene hydrocarbons and their derivatives are characteristic fern metabolites, and are also chemophenetic markers. Recently, our biosynthetic study into fern squalene cyclases (SCs), the enzymes responsible for triterpene synthesis, gave an unexpected inconsistency between genotype (enzyme function) and chemotype (triterpene profile). This finding prompted us to propose a hypothesis that SC genes are widely distributed throughout ferns and lycophytes whether or not they produce triterpene hydrocarbons. To test this hypothesis, we employed a multifaceted approach based on phytochemical, biochemical, and phylogenetic analyses. As anticipated, we successfully isolated two SC pseudogenes from a fern from in which no or only one triterpene hydrocarbon was detected. Subsequent mutagenesis experiments resulted in the functional conversion of these pseudogenes into active SC genes. Given an auxiliary hypothesis regarding the inherent limit of the degenerate polymerase chain reaction (PCR) method, the overall dataset supported our hypothesis, although correction was required with respect to plant coverage. Not only did the corrected hypothesis outline the distribution of SC genes throughout ferns, it provided insight into the molecular basis of the triterpene-based chemophenetics in ferns, which is also discussed.
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Helechos/metabolismo , Triterpenos/metabolismo , Clonación Molecular , Evolución Molecular , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Liasas/genética , Liasas/metabolismo , Espectroscopía de Resonancia Magnética , Biología Molecular , Filogenia , Pichia/genética , Alineación de SecuenciaRESUMEN
Patients often experience temporary difficulty in masticating during the period immediately following dental treatment. The purpose of this study was to investigate subjectively assessed satisfaction with a specially designed diet for such patients by means of a questionnaire. These "easy-to-eat meals" were planned and provided by this hospital in Japan, and comprised a combination of commercially available and nutritionally rich soft foods, jellied foods, drinks, and other items. The patients were required to commence consuming them immediately following dental treatment. The questionnaire contained 6 categories -Satisfaction, Taste, Meal completion, Convenience, Reduction in discomfort, and Likelihood of reuse - to be evaluated on a 10-cm visual analog scale (VAS). The overall response was positive in all 41 completed questionnaires, with an overall score of 6 or higher for every category. Orthodontics achieved the highest VAS score in every category, followed by oral implantology, prosthodontics, and conservative Original Article doi:10.2209/tdcpublication.2018-0055 dentistry. A correlation was observed between Satisfaction and each of the 5 remaining questionnaire categories (Taste: |r|=0.70, p≤0.00; Meal completion: |r|=0.60, p≤0.00; Convenience: |r|=0.56, p≤0.00; Reduction in discomfort: |r|=0.48, p=0.00; and Likelihood of reuse: |r|=0.79, p≤0.00). An acceptable level of convenience was obtained with these meals, as they were reported to be useful during the period immediately following treatment, when eating out or preparing meals was physically and/or psychologically difficult.
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Dieta , Pacientes Ambulatorios , Atención Odontológica , Conducta Alimentaria , Humanos , Japón , Encuestas y CuestionariosRESUMEN
Increased concentrations of atmospheric CO2 are predicted to reduce the content of essential elements such as protein, zinc, and iron in C3 grains and legumes, threatening the nutrition of billions of people in the next 50 years. However, this prediction has mostly been limited to grain crops, and moreover, we have little information about either the underlying mechanism or an effective intervention to mitigate these reductions. Here, we present a broader picture of the reductions in elemental content among crops grown under elevated CO2 concentration. By using a new approach, flow analysis of elements, we show that lower absorption and/or translocation to grains is a key factor underlying such elemental changes. On the basis of these findings, we propose two effective interventions-namely, growing C4 instead of C3 crops, and genetic improvements-to minimize the elemental changes in crops, and thereby avoid an impairment of human nutrition under conditions of elevated CO2.
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Atmósfera/química , Dióxido de Carbono/fisiología , Producción de Cultivos/métodos , Productos Agrícolas/fisiología , Fotosíntesis/fisiología , Producción de Cultivos/tendencias , Productos Agrícolas/química , Fabaceae/química , Fabaceae/fisiología , Conducta Alimentaria/fisiología , Abastecimiento de Alimentos , Humanos , Micronutrientes/administración & dosificación , Micronutrientes/fisiología , Oryza/química , Oryza/fisiología , Plantas Modificadas Genéticamente/química , Plantas Modificadas Genéticamente/fisiologíaRESUMEN
In High Arctic tundra ecosystems, seabird colonies create nitrogen cycling hotspots because of bird-derived labile organic matter. However, knowledge about the nitrogen cycle in such ornithocoprophilous tundra is limited. Here, we determined denitrification potentials and in-situ nitrous oxide (N2O) emissions of surface soils on plant-covered taluses under piscivorous seabird cliffs at two sites (BL and ST) near Ny-Ålesund, Svalbard, in the European High Arctic. Talus soils at both locations had very high denitrification potentials at 10 °C (2.62-4.88 mg N kg-1 dry soil h-1), near the mean daily maximum air temperature in July in Ny-Ålesund, with positive temperature responses at 20 °C (Q10 values, 1.6-2.3). The talus soils contained abundant denitrification genes, suggesting that they are denitrification hotspots. However, high in-situ N2O emissions, indicating the presence of both active aerobic nitrification and anaerobic denitrification, were observed only at BL (max. 16.6 µg N m-2 h-1). Rapid nitrogen turnover at BL was supported by lower carbon-to-nitrogen ratios, higher nitrate content, and higher δ15N values in the soils at BL compared with those at ST. These are attributed to the 30-fold larger seabird density at BL than at ST, providing the larger organic matter input.