RESUMO
Triage strategies are needed for primary human papillomavirus (HPV)-based cervical cancer screening to identify women requiring colposcopy/biopsy. We assessed the performance of p16/Ki-67 dual-stained (DS) immunocytochemistry to triage HPV-positive women and compared it to cytology, with or without HPV16/18 genotyping. A prospective observational screening study enrolled 35 263 women aged 25 to 65 years at 32 U.S. sites. Cervical samples had HPV and cytology testing, with colposcopy/biopsy for women with positive tests. Women without cervical intraepithelial neoplasia Grade 2 or worse (≥CIN2) at baseline (n = 3876) were retested after 1 year. In all, 4927 HPV-positive women with valid DS results were included in this analysis. DS sensitivity for ≥CIN2 and ≥CIN3 at baseline was 91.2% (95% confidence interval [CI]: 86.8%-94.2%) and 91.9% (95% CI: 86.1%-95.4%), respectively, in HPV16/18-positive women and 83.0% (95% CI: 78.4%-86.8%) and 86.0% (95% CI: 77.5%-91.6%) in women with 12 "other" genotypes. Using DS alone to triage HPV-positive women showed significantly higher sensitivity and specificity than HPV16/18 genotyping with cytology triage of 12 "other" genotypes, and substantially higher sensitivity but lower specificity than using cytology alone. The risk of ≥CIN2 was significantly lower in HPV-positive, DS-negative women (3.6%; 95% CI: 2.9%-4.4%), compared to triage-negative women using HPV16/18 genotyping with cytology for 12 "other" genotypes (7.4%; 95% CI: 6.4%-8.5%; P < .0001) or cytology alone (7.5%; 95% CI: 6.7%-8.4%; P < .0001). DS showed better risk stratification than cytology-based strategies and provided high reassurance against pre-cancers both at baseline and at 1-year follow-up, irrespective of the HPV genotype. DS allows for the safe triage of primary screening HPV-positive women.
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Inibidor p16 de Quinase Dependente de Ciclina/análise , Papillomavirus Humano 16/isolamento & purificação , Papillomavirus Humano 18/isolamento & purificação , Antígeno Ki-67/análise , Neoplasias do Colo do Útero/virologia , Adulto , Idoso , Colposcopia , Feminino , Genótipo , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , Estudos Prospectivos , Triagem , Neoplasias do Colo do Útero/química , Neoplasias do Colo do Útero/patologiaRESUMO
Pathologists have had increasing responsibility for quantitating immunohistochemistry (IHC) biomarkers with the expectation of high between-reader reproducibility due to clinical decision-making especially for patient therapy. Digital imaging-based quantitation of IHC clinical slides offers a potential aid for improvement; however, its clinical adoption is limited potentially due to a conventional field-of-view annotation approach. In this study, we implemented a novel solely morphology-based whole tumor section annotation strategy to maximize image analysis quantitation results between readers. We first compare the field-of-view image analysis annotation approach to digital and manual-based modalities across multiple clinical studies (~120 cases per study) and biomarkers (ER, PR, HER2, Ki-67, and p53 IHC) and then compare a subset of the same cases (~40 cases each from the ER, PR, HER2, and Ki-67 studies) using whole tumor section annotation approach to understand incremental value of all modalities. Between-reader results for each biomarker in relation to conventional scoring modalities showed similar concordance as manual read: ER field-of-view image analysis: 95.3% (95% CI 92.0-98.2%) vs digital read: 92.0% (87.8-95.8%) vs manual read: 94.9% (91.4-97.8%); PR field-of-view image analysis: 94.1% (90.3-97.2%) vs digital read: 94.0% (90.2-97.1%) vs manual read: 94.4% (90.9-97.2%); Ki-67 field-of-view image analysis: 86.8% (82.1-91.4%) vs digital read: 76.6% (70.9-82.2%) vs manual read: 85.6% (80.4-90.4%); p53 field-of-view image analysis: 81.7% (76.4-86.8%) vs digital read: 80.6% (75.0-86.0%) vs manual read: 78.8% (72.2-83.3%); and HER2 field-of-view image analysis: 93.8% (90.0-97.2%) vs digital read: 91.0 (86.6-94.9%) vs manual read: 87.2% (82.1-91.9%). Subset implementation and analysis on the same cases using whole tumor section image analysis approach showed significant improvement between pathologists over field-of-view image analysis and manual read (HER2 100% (97-100%), P=0.013 field-of-view image analysis and 0.013 manual read; Ki-67 100% (96.9-100%), P=0.040 and 0.012; ER 98.3% (94.1-99.5%), p=0.232 and 0.181; and PR 96.6% (91.5-98.7%), p=0.012 and 0.257). Overall, whole tumor section image analysis significantly improves between-pathologist's reproducibility and is the optimal approach for clinical-based image analysis algorithms.
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Biomarcadores Tumorais/análise , Neoplasias da Mama/química , Neoplasias da Mama/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Imuno-Histoquímica/métodos , Biomarcadores Tumorais/química , Feminino , Humanos , Antígeno Ki-67/análise , Antígeno Ki-67/química , Proteína Supressora de Tumor p53/análise , Proteína Supressora de Tumor p53/químicaRESUMO
There is broad consensus among paleoanthropologists that meat-eating played a key role in the evolution of Homo, but the details of where, when, and why are hotly debated. It has been argued that increased faunivory was causally connected with hominin adaptation to open, savanna habitats. If savanna-dwelling chimpanzees eat meat more frequently than do forest chimpanzees, it would support the notion that open, dry, seasonal habitats promote hunting or scavenging by hominoids. Here we present observational and fecal analysis data on vertebrate consumption from several localities within the dry, open Ugalla region of Tanzania. Combining these with published fecal analyses, we summarize chimpanzee vertebrate consumption rates, showing quantitatively that savanna chimpanzee populations do not differ significantly from forest populations. Compared with forest populations, savanna chimpanzees consume smaller vertebrates that are less likely to be shared, and they do so more seasonally. Analyses of chimpanzee hunting that focus exclusively on capture of forest monkeys are thus difficult to apply to chimpanzee faunivory in open-country habitats and may be misleading when used to model early hominin behavior. These findings bear on discussions of why chimpanzees hunt and suggest that increases in hominin faunivory were related to differences between hominins and chimpanzees and/or differences between modern and Pliocene savanna woodland environments.
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Dieta , Pan troglodytes/fisiologia , Comportamento Predatório , Animais , Florestas , Pradaria , Tanzânia , VertebradosRESUMO
Comparative data on the diets of extant primates inform hypotheses about hominin resource use. Historically, data describing chimpanzee diets stem primarily from forest-dwelling communities, and we lack comparative data from chimpanzees that live in mosaic habitats that more closely resemble those reconstructed for Plio-Pleistocene hominins. We present data on the diet of a partially-habituated community of open habitat chimpanzees (Pan troglodytes schweinfurthii) from the Issa valley, western Tanzania, collected over a four-year period. Based mostly on macroscopic faecal analysis, Issa chimpanzees consumed a minimum of 69 plant species. There was no relationship between plant consumption and either fruit availability or feeding tree density; the most frequently consumed plant species were found in riverine forests, with woodland species consumed more frequently during the late dry season. We conclude by contextualising these findings with those of other open-habitat chimpanzee sites, and also by discussing how our results contribute towards reconstructions of early hominin exploitation of mosaic landscapes.
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Dieta , Pan troglodytes/fisiologia , Animais , Ecossistema , TanzâniaRESUMO
HER2 gene-protein assay (GPA) is a new method for the simultaneous evaluation of HER2 immunohistochemistry (IHC) and HER2 dual in situ hybridization (DISH) on single tissue sections of breast cancer. We investigated the presence of HER2 gene and protein discrepancy and HER2-heterogeneity using HER2-GPA. HER2 status was analyzed for the correlation between the presence of HER2-heterogeneity and patient prognosis. Consecutive 280 invasive breast cancer were examined. Statuses of HER2 protein and gene were evaluated in whole tumor sections of HER2 GPA slides. HER2 protein and gene combination patterns were classified to six phenotypic and genotypic types for each case, as well as at individual cell levels: (A) IHC and DISH positive; (B) IHC positive and DISH negative; (C) IHC equivocal and DISH positive; (D) IHC equivocal and DISH negative; (E) IHC negative and DISH positive; and (F) IHC and DISH negative. The presence of HER2-heterogeneity was determined by the existence of at least two of six types within one tumor. HER2-IHC positive patients had significantly worse survival than IHC negative patients and HER2-DISH positive patients had significantly worse survival than DISH negative patients. HER2 IHC negative and DISH positive patients had significantly worse recurrence-free survival than IHC and DISH negative patients. In the HER2 IHC and DISH negative group, the HER2 heterogeneous group had significantly worse survival than the nonheterogeneous group. Notably, among triple negative breast cancer (TNBC), the HER2 heterogeneous group had significantly worse survival than the nonheterogeneous group. Our study suggests that the presence of HER2-heterogeneity might be a prognostic factor in HER2 negative breast cancer patients, especially in TNBC.
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Neoplasias da Mama/metabolismo , Receptor ErbB-2/genética , Receptor ErbB-2/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/genética , Feminino , Heterogeneidade Genética , Humanos , Pessoa de Meia-Idade , Prognóstico , Análise de SobrevidaRESUMO
Diet influences the stable isotope ratios of carbon and nitrogen (δ(13) C and δ(15) N values) in animal tissue; but here we explore the influences of particular aspects of the local environment on those values in chimpanzees (Pan troglodytes). In this article we present new δ(13) C and δ(15) N values in Gombe chimpanzees using hairs collected from night nests in 1989. Then, we explore the influence of environmental factors by comparing our Gombe data to those from eight additional Pan study sites with previously published stable isotope data. We compare chimpanzee δ(13) Chair and δ(15) Nhar values to specific characteristics of local site ecology (biome and ecoregion) and to local Mean Annual Precipitation (MAP) to test hypotheses based on known effects of these variables on the δ(13) C and δ(15) N values in plant tissues. The comparison shows that hair from chimpanzees living in savanna sites with lower MAP have higher δ(13) Chair values than do chimpanzees living in woodland and forested sites with higher MAP. These results demonstrate the potential of using δ(13) C values in primate tissue to indicate aspects of their local ecology in cases where the ecology is uncertain, such as samples collected early in the last century and in fossil hominins. In contrast to expectations, however, chimpanzee δ(15) Nhair values from some savanna sites with lower MAP are lower, not higher, than those living in more forested areas with higher MAP. It is likely that diet selectivity by chimpanzees affects δ(15) Nhair values to a greater extent than does the influence of precipitation on plants. Am. J. Primatol. 78:1055-1069, 2016. © 2015 Wiley Periodicals, Inc.
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Isótopos de Carbono , Cabelo/química , Isótopos de Nitrogênio , Pan troglodytes , Animais , Carbono , Dieta , Meio Ambiente , NitrogênioRESUMO
BACKGROUND: Treatment for patients with breast cancer (BC) is guided by human epidermal growth factor receptor 2 (HER2) status. The patient's HER2 status is assessed using US Food and Drug Administration-approved in vitro diagnostic (IVD) immunohistochemical (IHC) tests and laboratory-developed IVD tests. We analysed HER2 testing accuracy using data from the Nordic Immunohistochemistry Quality Control (NordiQC) HER2 IHC programme; results were used in an economic BC treatment model. METHODS: Data were obtained from NordiQC HER2 BC surveys performed from 2008 to 2012. False-negative (FN) and false-positive (FP) rates for approved and laboratory-developed IVDs were used to estimate direct costs, loss of survival, productivity benefit and quality-adjusted life-years. In the absence of consistent and accessible clinical and economic data from countries participating in the NordiQC programme, United States productivity data, healthcare costs and patient numbers were used as a surrogate in order to estimate the potential impact of selecting an approved or laboratory-developed IVDs. RESULTS: In total, 1703 tests were performed. Pooled FN rates were 11% for approved IVDs and 25% for laboratory-developed IVDs; FP rates were 0% and 5%, respectively. Using these FP and FN rates in the economic model and applying them to the United States BC population, approved IVD tests would result in better clinical outcomes, i.e., better survival and fewer disease recurrences/progressions, and lower costs, i.e., total direct costs and lost productivity, versus laboratory-developed IVD tests. Every $1 saved by laboratories by using cheaper reagents could potentially result in approximately $6 additional costs to the healthcare system. CONCLUSIONS: The results of this analysis suggest that incorrect HER2 test results have far-reaching clinical and economic consequences.
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Neoplasias da Mama/tratamento farmacológico , Erros de Diagnóstico/economia , Imuno-Histoquímica/normas , Receptor ErbB-2/análise , Feminino , Custos de Cuidados de Saúde , Humanos , Recidiva Local de Neoplasia , Anos de Vida Ajustados por Qualidade de Vida , Fatores Socioeconômicos , Estados UnidosRESUMO
INTRODUCTION: Heart failure (HF) is increasingly common and associated with excess morbidity, mortality, and healthcare costs. Treatment of HF can alter the disease trajectory and reduce clinical events in HF. However, many cases of HF remain undetected until presentation with more advanced symptoms, often requiring hospitalisation. Predicting incident HF is challenging and statistical models are limited by performance and scalability in routine clinical practice. An HF prediction model implementable in nationwide electronic health records (EHRs) could enable targeted diagnostics to enable earlier identification of HF. METHODS AND ANALYSIS: We will investigate a range of development techniques (including logistic regression and supervised machine learning methods) on routinely collected primary care EHRs to predict risk of new-onset HF over 1, 5 and 10 years prediction horizons. The Clinical Practice Research Datalink (CPRD)-GOLD dataset will be used for derivation (training and testing) and the CPRD-AURUM dataset for external validation. Both comprise large cohorts of patients, representative of the population of England in terms of age, sex and ethnicity. Primary care records are linked at patient level to secondary care and mortality data. The performance of the prediction model will be assessed by discrimination, calibration and clinical utility. We will only use variables routinely accessible in primary care. ETHICS AND DISSEMINATION: Permissions for CPRD-GOLD and CPRD-AURUM datasets were obtained from CPRD (ref no: 21_000324). The CPRD ethical approval committee approved the study. The results will be submitted as a research paper for publication to a peer-reviewed journal and presented at peer-reviewed conferences. TRIAL REGISTRATION DETAILS: The study was registered on Clinical Trials.gov (NCT05756127). A systematic review for the project was registered on PROSPERO (registration number: CRD42022380892).
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Registros Eletrônicos de Saúde , Insuficiência Cardíaca , Humanos , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/epidemiologia , Calibragem , Inglaterra , Etnicidade , Revisões Sistemáticas como AssuntoRESUMO
Increasing numbers of people are seeking assisted conception. In people with known cardiac disease or risk factors for cardiac disease, assisted conception may carry increased risks during treatment and any subsequent pregnancy. These risks should be assessed, considered and minimized prior to treatment.
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Doenças Cardiovasculares , Cardiopatias , Feminino , Gravidez , Humanos , Reprodução , Fertilização , Fatores de RiscoRESUMO
Data on chimpanzee (Pan troglodytes) nesting patterns were collected in Issa, Ugalla, western Tanzania. Ugalla is one of the driest, most open, and seasonal habitats inhabited by chimpanzees. We investigated the physical characteristics of nests and trees used for nesting to understand environmental influences on nest building and identify the characteristics preferred by the chimpanzees and the basis for such preferences. We analyzed 2,167 nests and 1,523 nesting trees. Most nests were built in the middle section of the tree crown and close to the tree trunk, and used a single tree in construction. Some physical characteristics of nests (e.g., distance from tree trunk) seemed to be the result of constraints imposed by tree structure. Issa chimpanzees preferred tall trees with high first branches for nesting supporting the hypothesis that elevated height of a sleeping place is a predator defense strategy. The height from the ground to the first branch showed less variation than either tree height or crown height and correlated weakly with tree height, suggesting that height from the ground to the first branch may be a more important factor than tree height alone in selecting a tree in which to nest. As in other study sites, the chimpanzees used tree species in proportions that did not correspond to their abundance suggesting tree species preference. We report for the first time that chimpanzees directionally oriented their nests and propose that this may be to maximize sunlight. We compare our data to those of other chimpanzee study sites.
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Ecossistema , Comportamento de Nidação/fisiologia , Pan troglodytes/fisiologia , Pan troglodytes/psicologia , Animais , Análise de Regressão , TanzâniaRESUMO
Studies about parasitization by Cryptosporidium in great apes have been scarce and mostly conducted in captivity. The present study reports the presence of Cryptosporidium sp. in wild chimpanzees (Pan troglodytes) from Ugalla, western Tanzania. Ugalla is one of the driest, most open, and seasonal habitats inhabited by chimpanzees. Cryptosporidium sp. was found in 8.9 % of the samples. The presence of the parasite was determined by preserving fecal samples in chemical conventional fixatives (MIF and alcohol absolute) staining them using a modified Zielh-Neelsen technique, and examining them with a light microscope. The number of fecal samples positive for Cryptosporidium was significantly higher during the rainy than during the dry season (p < 0.005). The results showed that feces collected in the rainy season were almost three times more likely to be positive for Cryptosporidium than those collected in the dry season (OR = 2.81). Cryptosporidium detection was significantly negatively affected by highest temperatures (>28.7 °C, p < 0.001). Cryptosporidiosis can cause serious health problems in humans and its potential effect on Ugalla chimpanzees is discussed.
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Criptosporidiose/veterinária , Cryptosporidium/isolamento & purificação , Doenças dos Primatas/epidemiologia , Animais , Clima , Criptosporidiose/epidemiologia , Criptosporidiose/parasitologia , Fezes/parasitologia , Microscopia , Pan troglodytes , Parasitologia , Prevalência , Doenças dos Primatas/parasitologia , Estações do Ano , Tanzânia/epidemiologiaRESUMO
Simian immunodeficiency virus of chimpanzees (SIVcpz) has a significant negative impact on the health, reproduction, and life span of chimpanzees, yet the prevalence and distribution of this virus in wild-living populations are still only poorly understood. Here, we show that savanna chimpanzees, who live in ecologically marginal habitats at 10- to 50-fold lower population densities than forest chimpanzees, can be infected with SIVcpz at high prevalence rates. Fecal samples were collected from nonhabituated eastern chimpanzees (Pan troglodytes schweinfurthii) in the Issa Valley (n = 375) and Shangwa River (n = 6) areas of the Masito-Ugalla region in western Tanzania, genotyped to determine the number of sampled individuals, and tested for SIVcpz-specific antibodies and nucleic acids. None of 5 Shangwa River apes tested positive for SIVcpz; however, 21 of 67 Issa Valley chimpanzees were SIVcpz infected, indicating a prevalence rate of 31% (95% confidence interval, 21% to 44%). Two individuals became infected during the 14-month observation period, documenting continuing virus spread in this community. To characterize the newly identified SIVcpz strains, partial and full-length viral sequences were amplified from fecal RNA of 10 infected chimpanzees. Phylogenetic analyses showed that the Ugalla viruses formed a monophyletic lineage most closely related to viruses endemic in Gombe National Park, also located in Tanzania, indicating a connection between these now separated communities at some time in the past. These findings document that SIVcpz is more widespread in Tanzania than previously thought and that even very low-density chimpanzee populations can be infected with SIVcpz at high prevalence rates. Determining whether savanna chimpanzees, who face much more extreme environmental conditions than forest chimpanzees, are more susceptible to SIVcpz-associated morbidity and mortality will have important scientific and conservation implications.
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Pan troglodytes/virologia , Síndrome de Imunodeficiência Adquirida dos Símios/epidemiologia , Síndrome de Imunodeficiência Adquirida dos Símios/virologia , Vírus da Imunodeficiência Símia/isolamento & purificação , Animais , Análise por Conglomerados , Fezes/virologia , Genótipo , Dados de Sequência Molecular , Filogenia , Prevalência , RNA Viral/genética , Análise de Sequência de DNA , TanzâniaRESUMO
Background: Identification of HER2 protein overexpression and/or amplification of the HER2 gene are required to qualify breast cancer patients for HER2 targeted therapies. In situ hybridization (ISH) assays that identify HER2 gene amplification function as a stand-alone test for determination of HER2 status and rely on the manual quantification of the number of HER2 genes and copies of chromosome 17 to determine HER2 amplification. Methods: To assist pathologists, we have developed the uPath HER2 Dual ISH Image Analysis for Breast (uPath HER2 DISH IA) algorithm, as an adjunctive aid in the determination of HER2 gene status in breast cancer specimens. The objective of this study was to compare uPath HER2 DISH image analysis vs manual read scoring of VENTANA HER2 DISH-stained breast carcinoma specimens with ground truth (GT) gene status as the reference. Three reader pathologists reviewed 220, formalin-fixed, paraffin-embedded (FFPE) breast cancer cases by both manual and uPath HER2 DISH IA methods. Scoring results from manual read (MR) and computer-assisted scores (image analysis, IA) were compared against the GT gene status generated by consensus of a panel of pathologists. The differences in agreement rates of HER2 gene status between manual, computer-assisted, and GT gene status were determined. Results: The positive percent agreement (PPA) and negative percent agreement (NPA) rates for image analysis (IA) vs GT were 97.2% (95% confidence interval [CI]: 95.0, 99.3) and 94.3% (95% CI: 90.8, 97.3) respectively. Comparison of agreement rates showed that the lower bounds of the 95% CIs for the difference of PPA and NPA for IA vs MR were -0.9% and -6.2%, respectively. Further, inter- and intra-reader agreement rates in the IA method were observed with point estimates of at least 96.7%. Conclusions: Overall, our data show that the uPath HER2 DISH IA is non-inferior to manual scoring and supports its use as an aid for pathologists in routine diagnosis of breast cancer.
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Early diagnosis and effective management of type 2 diabetes (T2D) are crucial in reducing the risk of developing life-changing complications such as heart failure, stroke, kidney disease, blindness and amputation, which are also associated with significant costs for healthcare providers. However, as T2D symptoms often develop slowly it is not uncommon for people to live with T2D for years without being aware of their condition-commonly known as the undiagnosed missing million. By the time a diagnosis is received, many individuals will have already developed serious complications. While the existence of undiagnosed diabetes has long been recognised, wide-reaching awareness among the general public, clinicians and policymakers is lacking, and there is uncertainty in how best to identify high-risk individuals. In this article we have used consensus expert opinion alongside the available evidence, to provide support for the diabetes healthcare community regarding risk prediction of the missing million. Its purpose is to provide awareness of the risk factors for identifying individuals at high, moderate and low risk of T2D and T2D-related complications. The awareness of risk predictors, particularly in primary care, is important, so that appropriate steps can be taken to reduce the clinical and economic burden of T2D and its complications.
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Sodium-glucose cotransporter 2 (SGLT2) inhibitors were first developed as glucose-lowering therapies for the treatment of diabetes. However, these drugs have now been recognised to prevent worsening heart-failure events, improve health-related quality of life, and reduce mortality in people with heart failure with reduced ejection fraction (HFrEF), including those both with and without diabetes. Despite robust clinical trial data demonstrating favourable outcomes with SGLT2 inhibitors for patients with HFrEF, there is a lack of familiarity with the HF indication for these drugs, which have been the remit of diabetologists to date. In this article we use consensus expert opinion alongside the available evidence and label indication to provide support for the healthcare community treating people with HF regarding positioning of SGLT2 inhibitors within the treatment pathway. By highlighting appropriate prescribing and practical considerations, we hope to encourage greater, and safe, use of SGLT2 inhibitors in this population.
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Insuficiência Cardíaca/tratamento farmacológico , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêutico , Fármacos Cardiovasculares/uso terapêutico , Análise Custo-Benefício , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/epidemiologia , Quimioterapia Combinada , Insuficiência Cardíaca/epidemiologia , Insuficiência Cardíaca/mortalidade , Humanos , Estudos Multicêntricos como Assunto , Guias de Prática Clínica como Assunto , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Inibidores do Transportador 2 de Sódio-Glicose/efeitos adversos , Inibidores do Transportador 2 de Sódio-Glicose/economia , Volume Sistólico/efeitos dos fármacosRESUMO
It has been hypothesized that plant underground storage organs (USOs) played key roles in the initial hominin colonization of savanna habitats, the development of the distinctive skull and tooth morphology of the genus Australopithecus, and the evolution of the genus Homo by serving as "fallback foods" exploited during periods of food shortage. These hypotheses have been tested mostly by morphological, isotopic, and microwear analyses of hominin bones and teeth. Archaeological evidence of USO digging technology is equivocal. Until now relevant data from studies of chimpanzees, useful in behavioral models of early hominins because of their phylogenetic proximity and anatomical similarities, have been lacking. Here we report on the first evidence of chimpanzees using tools to dig for USOs, suggesting that exploitation of such resources was within the cognitive and technological reach of the earliest hominins. Consistent with scenarios of hominin adaptation to savannas, these data come from Ugalla (Tanzania), one of the driest, most open and seasonal chimpanzee habitats. USOs are, however, exploited during the rainy season, well after the period of most likely food shortage, contradicting the specific prediction of fallback food hypotheses. The discovery that savanna chimpanzees use tools to obtain USOs contradicts yet another claim of human uniqueness and provides a model for the study of variables influencing USO use among early hominins.