Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 94
Filtrar
1.
AJNR Am J Neuroradiol ; 43(12): 1784-1791, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36456082

RESUMO

BACKGROUND AND PURPOSE: Social media has made inroads in medical education. We report the creation and 3-year (2018-2021) longitudinal assessment of the American Society of Head and Neck Radiology Case of the Week (#ASHNRCOTW), assessing viewership, engagement, and impact of the coronavirus disease 2019 (COVID-19) pandemic on this Twitter-based education initiative. MATERIALS AND METHODS: Unknown cases were tweeted from the American Society of Head and Neck Radiology account weekly. Tweet impressions (number of times seen), engagements (number of interactions), and new followers were tabulated. A social media marketing platform identified worldwide distribution of Twitter followers. Summary and t test statistics were performed. RESULTS: #ASHNRCOTW was highly visible with 2,082,280 impressions and 203,137 engagements. There were significantly greater mean case impressions (9917 versus 6346), mean case engagements (1305 versus 474), case engagement rates (13.06% versus 7.76%), mean answer impressions (8760 versus 5556), mean answer engagements (908 versus 436), answer engagement rates (10.38% versus 7.87%), mean total (case + answer) impressions (18,677 versus 11,912), mean total engagements (2214 versus 910), and total engagement rates (11.79% versus 7.69%) for cases published after the pandemic started (all P values < .001). There was a significant increase in monthly new followers after starting #ASHNRCOTW (mean, 134 versus 6; P < .001) and significantly increased monthly new followers after the pandemic started compared with prepandemic (mean, 178 versus 101; P = .003). The American Society of Head and Neck Radiology has 7564 Twitter followers throughout 130 countries (66% outside the United States). CONCLUSIONS: Social media affords substantial visibility, engagement, and global outreach for radiology education. #ASHNRCOTW viewership and engagement increased significantly during the COVID-19 pandemic.


Assuntos
COVID-19 , Radiologia , Mídias Sociais , Humanos , Estados Unidos , Pandemias/prevenção & controle , Radiologia/educação , Escolaridade
2.
AJNR Am J Neuroradiol ; 43(12): 1792-1796, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36423954

RESUMO

BACKGROUND AND PURPOSE: Patients with surgically resected vestibular schwannoma will undergo multiple postoperative surveillance examinations, typically including postcontrast sequences. The purpose of this study was to compare high-resolution T2WI with gadolinium T1WI in the postoperative assessment of vestibular schwannoma. MATERIALS AND METHODS: This was a retrospective study of patients with a history of resected vestibular schwannoma at a single institution. High-resolution T2WI and gadolinium T1WI were independently evaluated for residual disease. In addition, 3D and 2D measurements were performed in the group of patients with residual tumor. Statistical analysis was performed to evaluate the agreement between sequences on the binary assessment (presence/absence of tumor on initial postoperative examination) and to evaluate the equivalence of measurements for the 2 sequences on 3D and 2D quantitative assessment in individuals with residual disease. RESULTS: One hundred forty-eight patients with retrosigmoid-approach resection of vestibular schwannomas were included in the final analysis. There was moderate-to-substantial agreement between the 2 sequences for the evaluation of the presence versus absence of tumor (Cohen κ coefficient = 0.78; 95% CI, 0.68-0.88). The 2 sequences were significantly equivalent for 2D and 3D quantitative assessments (short-axis P value = .021; long-axis P value = .015; 3D P value = .039). CONCLUSIONS: In this retrospective study, we demonstrate moderate-to-substantial agreement in the categoric assessment for the presence versus absence of tumor and equivalence between the 2 sequences for both 2D and volumetric tumor measurements as performed in the subset of patients with measurable residual. On the basis of these results, high-resolution T2WI alone may be sufficient for early postoperative imaging surveillance in this patient population.


Assuntos
Neuroma Acústico , Humanos , Neuroma Acústico/diagnóstico por imagem , Neuroma Acústico/cirurgia , Neoplasia Residual , Estudos Retrospectivos , Gadolínio , Imageamento por Ressonância Magnética/métodos
3.
AJNR Am J Neuroradiol ; 43(8): 1090-1098, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35863785

RESUMO

Intraosseous venous malformations represent a subtype of venous vascular malformations that arise primarily in bone. In the head and neck, intraosseous venous malformations are most frequently found in the skull, skull base, and facial skeleton, with location at the geniculate ganglion of the facial nerve perhaps the most widely recognized. These non-neoplastic lesions are characterized by dilated venous channels with characteristic internal bony spicules on CT but may present with a more complex appearance on MR imaging and may share features with more aggressive lesions. Further confounding the imaging-based diagnosis of intraosseous venous malformation is the frequent misrepresentation of these lesions as hemangiomas in the radiology and clinical literature, as well as in daily practice. Because most intraosseous venous malformations can be left alone, their correct diagnosis may spare a patient unnecessary concern and intervention.


Assuntos
Tomografia Computadorizada por Raios X , Malformações Vasculares , Humanos , Tomografia Computadorizada por Raios X/métodos , Malformações Vasculares/diagnóstico por imagem , Malformações Vasculares/patologia , Cabeça/diagnóstico por imagem , Crânio/anormalidades , Pescoço/diagnóstico por imagem
4.
AJNR Am J Neuroradiol ; 42(3): E12, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33122217
5.
AJNR Am J Neuroradiol ; 41(11): 2001-2008, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32819899

RESUMO

BACKGROUND AND PURPOSE: A large spectrum of neurologic disease has been reported in patients with coronavirus disease 2019 (COVID-19) infection. Our aim was to investigate the yield of neuroimaging in patients with COVID-19 undergoing CT or MR imaging of the brain and to describe associated imaging findings. MATERIALS AND METHODS: We performed a retrospective cohort study involving 2054 patients with laboratory-confirmed COVID-19 presenting to 2 hospitals in New York City between March 4 and May 9, 2020, of whom 278 (14%) underwent either CT or MR imaging of the brain. All images initially received a formal interpretation from a neuroradiologist within the institution and were subsequently reviewed by 2 neuroradiologists in consensus, with disputes resolved by a third neuroradiologist. RESULTS: The median age of these patients was 64 years (interquartile range, 50-75 years), and 43% were women. Among imaged patients, 58 (21%) demonstrated acute or subacute neuroimaging findings, the most common including cerebral infarctions (11%), parenchymal hematomas (3.6%), and posterior reversible encephalopathy syndrome (1.1%). Among the 51 patients with MR imaging examinations, 26 (51%) demonstrated acute or subacute findings; notable findings included 6 cases of cranial nerve abnormalities (including 4 patients with olfactory bulb abnormalities) and 3 patients with a microhemorrhage pattern compatible with critical illness-associated microbleeds. CONCLUSIONS: Our experience confirms the wide range of neurologic imaging findings in patients with COVID-19 and suggests the need for further studies to optimize management for these patients.


Assuntos
Encefalopatias/diagnóstico por imagem , Encefalopatias/virologia , Infecções por Coronavirus/complicações , Pneumonia Viral/complicações , Idoso , Betacoronavirus , COVID-19 , Estudos de Coortes , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Cidade de Nova Iorque , Pandemias , Estudos Retrospectivos , SARS-CoV-2
6.
AJNR Am J Neuroradiol ; 41(10): 1882-1887, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32855190

RESUMO

BACKGROUND AND PURPOSE: Unique among the acute neurologic manifestations of Severe Acute Respiratory Syndrome coronavirus 2, the virus responsible for the coronavirus disease 2019 (COVID-19) pandemic, is chemosensory dysfunction (anosmia or dysgeusia), which can be seen in patients who are otherwise oligosymptomatic or even asymptomatic. The purpose of this study was to determine if there is imaging evidence of olfactory apparatus pathology in patients with COVID-19 and neurologic symptoms. MATERIALS AND METHODS: A retrospective case-control study compared the olfactory bulb and olfactory tract signal intensity on thin-section T2WI and postcontrast 3D T2 FLAIR images in patients with COVID-19 and neurologic symptoms, and age-matched controls imaged for olfactory dysfunction. RESULTS: There was a significant difference in normalized olfactory bulb T2 FLAIR signal intensity between the patients with COVID-19 and the controls with anosmia (P = .003). Four of 12 patients with COVID-19 demonstrated intraneural T2 signal hyperintensity on postcontrast 3D T2 FLAIR compared with none of the 12 patients among the controls with anosmia (P = .028). CONCLUSIONS: Olfactory bulb 3D T2 FLAIR signal intensity was greater in the patients with COVID-19 and neurologic symptoms compared with an age-matched control group with olfactory dysfunction, and this was qualitatively apparent in 4 of 12 patients with COVID-19. Analysis of these preliminary finding suggests that olfactory apparatus vulnerability to COVID-19 might be supported on conventional neuroimaging and may serve as a noninvasive biomarker of infection.


Assuntos
Betacoronavirus , Infecções por Coronavirus/complicações , Transtornos do Olfato/diagnóstico por imagem , Bulbo Olfatório/diagnóstico por imagem , Pneumonia Viral/complicações , Idoso , COVID-19 , Feminino , Humanos , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Transtornos do Olfato/etiologia , Transtornos do Olfato/fisiopatologia , Bulbo Olfatório/fisiopatologia , Pandemias , Estudos Retrospectivos , SARS-CoV-2
7.
AJNR Am J Neuroradiol ; 41(6): 960-965, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32354706

RESUMO

During the Severe Acute Respiratory Syndrome Coronavirus 2 (COVID-19) pandemic, neuroradiology practices have experienced a paradigm shift in practice, which affected everything from staffing, workflow, work volumes, conferences, resident and fellowship education, and research. This article highlights adaptive strategies that were undertaken at the epicenter of the outbreak in New York City during the past 4-6 weeks, as experienced by 5 large neuroradiology academic departments.


Assuntos
Infecções por Coronavirus , Neurologia/organização & administração , Pandemias , Pneumonia Viral , Radiologia/organização & administração , Fluxo de Trabalho , Betacoronavirus , COVID-19 , Humanos , Cidade de Nova Iorque , Serviço Hospitalar de Radiologia/organização & administração , SARS-CoV-2
8.
AJNR Am J Neuroradiol ; 40(4): 584-590, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30765377

RESUMO

The sinonasal tract is an environment diverse with neoplasia. Given the continued discovery of entities generally specific to the sinonasal tract, the fourth edition of the World Health Organization Classification of Head and Neck Tumors was released in 2017. It describes 3 new, well-defined entities and several less-defined, emerging entities. The new entities are seromucinous hamartomas, nuclear protein in testis carcinomas, and biphenotypic sinonasal sarcomas. Emerging entities include human papillomavirus-related sinonasal carcinomas, SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1-deficient sinonasal carcinomas, renal cell-like adenocarcinomas, and chondromesenchymal hamartomas. The literature thus far largely focuses on the pathology of these entities. Our goal in this report was to familiarize radiologists with these new diagnoses and to provide available information regarding their imaging appearances.


Assuntos
Neoplasias dos Seios Paranasais/diagnóstico por imagem , Neoplasias dos Seios Paranasais/patologia , Humanos , Organização Mundial da Saúde
9.
AJNR Am J Neuroradiol ; 39(8): 1509-1514, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29903925

RESUMO

BACKGROUND AND PURPOSE: Skull base chordomas often demonstrate variable MR imaging characteristics, and there has been limited prior research investigating the potential clinical relevance of this variability. The purpose of this retrospective study was to assess the prognostic implications of signal intensity on standard imaging techniques for the biologic behavior of skull base chordomas. MATERIALS AND METHODS: Medical records were retrospectively reviewed for 22 patients with pathologically confirmed skull base chordomas. Clinical data were recorded, including the degree of surgical resection, the presence or absence of radiation therapy, and time to progression/recurrence of the tumor or time without progression/recurrence of the tumor following initial treatment. Pretreatment imaging was reviewed for the presence or absence of enhancement and the T2 signal characteristics. Tumor-to-brain stem signal intensity ratios on T2, precontrast T1, and postcontrast T1 spin-echo sequences were also calculated. Statistical analysis was then performed to assess correlations between imaging characteristics and tumor progression/recurrence. RESULTS: Progression/recurrence of skull base chordomas was seen following surgical resection in 11 of 14 (78.6%) patients with enhancing tumors and in zero of 8 patients with nonenhancing tumors. There was a statistically significant correlation between skull base chordoma enhancement and subsequent tumor progression/recurrence (P < .001), which remained significant after controlling for differences in treatment strategy (P < .001). There was also a correlation between postcontrast T1 signal intensity (as measured by postcontrast T1 tumor-to-brain stem signal intensity ratios) and recurrence/progression (P = .02). While T2 signal intensity was higher in patients without tumor progression (median tumor-to-brain stem signal intensity ratios on T2 = 2.27) than in those with progression (median tumor-to-brain stem signal intensity ratios on T2 = 1.78), this association was not significant (P = .12). CONCLUSIONS: Enhancement of skull base chordomas is a risk factor for tumor progression/recurrence following surgical resection.


Assuntos
Cordoma/diagnóstico por imagem , Cordoma/patologia , Imageamento por Ressonância Magnética/métodos , Neoplasias da Base do Crânio/diagnóstico por imagem , Neoplasias da Base do Crânio/patologia , Adulto , Idoso , Cordoma/cirurgia , Meios de Contraste , Feminino , Gadolínio , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/epidemiologia , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Neoplasias da Base do Crânio/cirurgia
10.
Diabetes Obes Metab ; 18(5): 519-27, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26876427

RESUMO

AIMS: To examine whether co-administration of intestinal alkaline phosphatase (IAP) with antibiotics early in life may have a preventive role against metabolic syndrome (MetS) in mice. METHODS: A total of 50 mice were allocated to four treatment groups after weaning. Mice were treated with azithromycin (AZT) ± IAP, or with no AZT ± IAP, for three intermittent 7-day cycles. After the last treatment course, the mice were administered a regular chow diet for 5 weeks and subsequently a high-fat diet for 5 weeks. Body weight, food intake, water intake, serum lipids, glucose levels and liver lipids were compared. 16S rRNA gene pyrosequencing was used to determine the differences in microbiome composition. RESULTS: Exposure to AZT early in life rendered mice susceptible to MetS in adulthood. Co-administration of IAP with AZT completely prevented this susceptibility by decreasing total body weight, serum lipids, glucose levels and liver lipids to the levels of control mice. These effects of IAP probably occur as a result of changes in the composition of specific bacterial taxa at the genus and species levels (e.g. members of Anaeroplasma and Parabacteroides). CONCLUSIONS: Co-administration of IAP with AZT early in life prevents mice from susceptibility to the later development of MetS. This effect is associated with alterations in the composition of the gut microbiota. IAP may represent a novel treatment against MetS in humans.


Assuntos
Fosfatase Alcalina/uso terapêutico , Antibacterianos/efeitos adversos , Azitromicina/efeitos adversos , Suplementos Nutricionais , Disbiose/prevenção & controle , Mucosa Intestinal/enzimologia , Síndrome Metabólica/prevenção & controle , Acholeplasma/classificação , Acholeplasma/efeitos dos fármacos , Acholeplasma/crescimento & desenvolvimento , Acholeplasma/isolamento & purificação , Fosfatase Alcalina/efeitos adversos , Animais , Bacteroides/classificação , Bacteroides/efeitos dos fármacos , Bacteroides/crescimento & desenvolvimento , Bacteroides/isolamento & purificação , Bovinos , Dieta Hiperlipídica/efeitos adversos , Suplementos Nutricionais/efeitos adversos , Disbiose/induzido quimicamente , Disbiose/microbiologia , Disbiose/fisiopatologia , Fezes/microbiologia , Microbioma Gastrointestinal/efeitos dos fármacos , Masculino , Síndrome Metabólica/complicações , Síndrome Metabólica/etiologia , Síndrome Metabólica/microbiologia , Camundongos Endogâmicos C57BL , Tipagem Molecular , Obesidade/complicações , Obesidade/etiologia , Obesidade/microbiologia , Obesidade/prevenção & controle , Desmame , Aumento de Peso/efeitos dos fármacos
11.
AJNR Am J Neuroradiol ; 37(2): 349-53, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26564432

RESUMO

BACKGROUND AND PURPOSE: The infraorbital nerve arises from the maxillary branch of the trigeminal nerve and normally traverses the orbital floor in the infraorbital canal. Sometimes, however, the infraorbital canal protrudes into the maxillary sinus separate from the orbital floor. We systematically studied the prevalence of this variant. MATERIALS AND METHODS: We performed a retrospective review of 500 consecutive sinus CTs performed at our outpatient centers. The infraorbital nerve protruded into the maxillary sinus if the entire wall of the infraorbital canal was separate from the walls of the sinus. We recorded the length of the bony septum that attached the infraorbital canal to the wall of the maxillary sinus and noted whether the protrusion was bilateral. We also measured the distance from the inferior orbital rim where the infraorbital canal begins to protrude into the sinus. RESULTS: There was a prevalence of 10.8% for infraorbital canal protrusion into the maxillary sinus and 5.6% for bilateral protrusion. The median length of the bony septum attaching the infraorbital canal to a maxillary sinus wall, which was invariably present, was 4 mm. The median distance at which the infraorbital nerve began to protrude into the sinus was 11 mm posterior to the inferior orbital rim. CONCLUSIONS: Although this condition has been reported in only 3 patients previously, infraorbital canal protrusion into the maxillary sinus was present in >10% of our cohort. Identification of this variant on CT could help a surgeon avoid patient injury.


Assuntos
Nervo Maxilar/anormalidades , Seio Maxilar/diagnóstico por imagem , Idoso , Feminino , Humanos , Masculino , Nervo Maxilar/diagnóstico por imagem , Pessoa de Meia-Idade , Prevalência , Estudos Retrospectivos , Tomografia Computadorizada por Raios X
12.
AJNR Am J Neuroradiol ; 36(7): 1355-61, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26066627

RESUMO

Parry Romberg syndrome is a rare progressive hemiatrophy of the face that typically occurs in children and young adults and has a peculiar progression that ceases without apparent cause after a highly variable period. Only a subset of patients with Parry Romberg syndrome will develop secondary neurologic or ophthalmologic symptoms, and prognosis is highly variable. Inconsistency in the pattern of atrophy and the development of associated symptoms in patients with Parry Romberg syndrome has made it challenging to diagnose, prognosticate, and treat. The precise etiology of this disease remains unknown, but some authors have implicated sympathetic cervical ganglion dysfunction, abnormal embryogenesis, autoimmune and inflammatory mechanisms, or vasculopathy as potential causes. We present 7 cases of Parry Romberg syndrome and their associated clinical and imaging findings with specific attention to the radiographic characteristics of this disease.


Assuntos
Hemiatrofia Facial/diagnóstico por imagem , Hemiatrofia Facial/patologia , Adulto , Criança , Humanos , Radiografia
13.
Mol Ecol ; 23(16): 3999-4017, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25041117

RESUMO

Although the grey seal Halichoerus grypus is one of the most familiar and intensively studied of all pinniped species, its global population structure remains to be elucidated. Little is also known about how the species as a whole may have historically responded to climate-driven changes in habitat availability and anthropogenic exploitation. We therefore analysed samples from over 1500 individuals collected from 22 colonies spanning the Western and Eastern Atlantic and the Baltic Sea regions, represented by 350 bp of the mitochondrial hypervariable region and up to nine microsatellites. Strong population structure was observed at both types of marker, and highly asymmetrical patterns of gene flow were also inferred, with the Orkney Islands being identified as a source of emigrants to other areas in the Eastern Atlantic. The Baltic and Eastern Atlantic regions were estimated to have diverged a little over 10 000 years ago, consistent with the last proposed isolation of the Baltic Sea. Approximate Bayesian computation also identified genetic signals consistent with postglacial population expansion across much of the species range, suggesting that grey seals are highly responsive to changes in habitat availability.


Assuntos
Fluxo Gênico , Genética Populacional , Focas Verdadeiras/genética , Animais , Oceano Atlântico , Teorema de Bayes , DNA Mitocondrial/genética , Ecossistema , Repetições de Microssatélites , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNA
14.
Ecol Evol ; 3(1): 18-37, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23403722

RESUMO

Patterns of genetic variation observed within species reflect evolutionary histories that include signatures of past demography. Understanding the demographic component of species' history is fundamental to informed management because changes in effective population size affect response to environmental change and evolvability, the strength of genetic drift, and maintenance of genetic variability. Species experiencing anthropogenic population reductions provide valuable case studies for understanding the genetic response to demographic change because historic changes in the census size are often well documented. A classic example is the bowhead whale, Balaena mysticetus, which experienced dramatic population depletion due to commercial whaling in the late 19th and early 20th centuries. Consequently, we analyzed a large multi-marker dataset of bowhead whales using a variety of analytical methods, including extended Bayesian skyline analysis and approximate Bayesian computation, to characterize genetic signatures of both ancient and contemporary demographic histories. No genetic signature of recent population depletion was recovered through any analysis incorporating realistic mutation assumptions, probably due to the combined influences of long generation time, short bottleneck duration, and the magnitude of population depletion. In contrast, a robust signal of population expansion was detected around 70,000 years ago, followed by a population decline around 15,000 years ago. The timing of these events coincides to a historic glacial period and the onset of warming at the end of the last glacial maximum, respectively. By implication, climate driven long-term variation in Arctic Ocean productivity, rather than recent anthropogenic disturbance, appears to have been the primary driver of historic bowhead whale demography.

15.
AJNR Am J Neuroradiol ; 33(3): 429-33, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22135127

RESUMO

BACKGROUND AND PURPOSE: 4D-CT is a novel method of multiphase CT imaging. When used to localize parathyroid adenomas and hyperplasia, this technique may allow for more robust diagnostic accuracy than traditional sonography and nuclear scintigraphy techniques. The purpose of our study is to assess the accuracy of 4D-CT for localizing pathologically proved parathyroid adenomas and hyperplasia found during surgery. MATERIALS AND METHODS: A total of 35 pathologically proved cases of parathyroid adenoma and hyperplasia were retrospectively reviewed between January 2009 and March 2011. Inclusion criteria were availability of final surgical pathology and performance of preoperative 4D-CT. No cases were excluded. Sensitivity, specificity, and accuracy of 4D-CT were ascertained including both the side and quadrant of the pathologically proved lesion. RESULTS: Of the 35 pathologically proved cases collected over the study period, 32 (sensitivity = 91%) patients were found positive for parathyroid disease using 4D-CT, including 3 cases of multigland disease. For lateralization of single-gland disease, 4D-CT demonstrated an accuracy of 93%. 4D-CT revealed a suboptimal 44% sensitivity, but 100% specificity, for multigland disease. CONCLUSIONS: 4D-CT demonstrated a high diagnostic accuracy for single and multigland disease in our cohort. Importantly, 4D-CT accurately lateralized single-gland adenomas in >90% of cases, allowing the surgeon to employ a directed operative approach. 4D-CT also showed a very high specificity for the detection of multigland disease.


Assuntos
Adenoma/diagnóstico por imagem , Imageamento Tridimensional/métodos , Iohexol , Neoplasias das Paratireoides/diagnóstico por imagem , Técnicas de Imagem de Sincronização Respiratória/métodos , Tomografia Computadorizada por Raios X/métodos , Meios de Contraste , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
Mol Ecol ; 20(19): 3989-4008, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21895820

RESUMO

Emerging Bayesian analytical approaches offer increasingly sophisticated means of reconstructing historical population dynamics from genetic data, but have been little applied to scenarios involving demographic bottlenecks. Consequently, we analysed a large mitochondrial and microsatellite dataset from the Antarctic fur seal Arctocephalus gazella, a species subjected to one of the most extreme examples of uncontrolled exploitation in history when it was reduced to the brink of extinction by the sealing industry during the late eighteenth and nineteenth centuries. Classical bottleneck tests, which exploit the fact that rare alleles are rapidly lost during demographic reduction, yielded ambiguous results. In contrast, a strong signal of recent demographic decline was detected using both Bayesian skyline plots and Approximate Bayesian Computation, the latter also allowing derivation of posterior parameter estimates that were remarkably consistent with historical observations. This was achieved using only contemporary samples, further emphasizing the potential of Bayesian approaches to address important problems in conservation and evolutionary biology.


Assuntos
Otárias/genética , Animais , Teorema de Bayes , Conservação dos Recursos Naturais , DNA Mitocondrial/química , Otárias/fisiologia , Genótipo , Repetições de Microssatélites , Densidade Demográfica , Dinâmica Populacional
17.
AJNR Am J Neuroradiol ; 32(7): 1208-11, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21659479

RESUMO

Although a relatively rare neoplasm, primary carcinoid tumor has an unusual propensity to metastasize to the orbits. Within the orbit, metastatic EOM lesions have been described in scattered reports in the ophthalmology literature but have received little to no attention in the radiology literature. After a retrospective review, we identified CT and MR imaging studies of 7 patients with carcinoid tumor metastatic to the EOM. Our findings suggest that in patients with known carcinoid tumor, well-defined, round, or fusiform masses of the EOM should strongly suggest metastatic involvement. Our series suggests that bilateral lesions may occur and that any EOM can be involved. Knowledge of this pattern of metastatic disease may spare biopsies in some patients, and with current orbit-sparing therapy for patients with localized orbital disease, early and accurate diagnosis can significantly improve patient outcomes.


Assuntos
Tumor Carcinoide/diagnóstico por imagem , Tumor Carcinoide/secundário , Músculos Oculomotores/diagnóstico por imagem , Músculos Oculomotores/patologia , Neoplasias Orbitárias/diagnóstico por imagem , Neoplasias Orbitárias/secundário , Adulto , Idoso , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X
18.
Mol Ecol ; 18(16): 3379-93, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19627492

RESUMO

Despite the widely recognized incidence of homoplasy characterizing this region, the hypervariable region I (HVRI) of the mitochondrial control region is one of the most frequently used genetic markers for population genetic and phylogeographic studies. We present an evolutionary analysis of HVRI and cytochrome b sequences from a range-wide survey of 1031 Steller sea lions, Eumetopias jubatus, to quantify homoplasy and substitution rate at HVRI. Variation in HVRI was distributed across 41 variable sites in the 238-bp segment examined. All variants at HVR1 were found to be transitions. However, our analyses suggest that a minimum of 101 changes have actually occurred within HVRI with as many as 18 substitutions occurring at a single site. By including this hidden variation into our analyses, several instances of apparent long-range dispersal were resolved to be homoplasies and 8.5-12% of observed HVRI haplotypes were found to have geographic distributions descriptive of convergent molecular evolution rather than identity by descent. We estimate the rate of substitution at HVRI in Steller sea lions to be approximately 24 times that of cytochrome b with an absolute rate of HVRI substitution estimated at 27.45% per million years. These findings have direct implications regarding the utility of HVRI data to generate a variety of evolutionary genetic hypotheses.


Assuntos
DNA Mitocondrial/genética , Evolução Molecular , Variação Genética , Leões-Marinhos/genética , Animais , Geografia , Haplótipos , Análise de Sequência de DNA
19.
Mol Ecol ; 18(14): 2961-78, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19500256

RESUMO

Many studies use genetic markers to explore population structure and variability within species. However, only a minority use more than one type of marker and, despite increasing evidence of a link between heterozygosity and individual fitness, few ask whether diversity correlates with population trajectory. To address these issues, we analysed data from the Steller's sea lion, Eumetiopias jubatus, where three stocks are distributed over a vast geographical range and where both genetic samples and detailed demographic data have been collected from many diverse breeding colonies. To previously published mitochondrial DNA (mtDNA) and microsatellite data sets, we have added new data for amplified fragment length polymorphism (AFLP) markers, comprising 238 loci scored in 285 sea lions sampled from 23 natal rookeries. Genotypic diversity was low relative to most vertebrates, with only 37 loci (15.5%) being polymorphic. Moreover, contrasting geographical patterns of genetic diversity were found at the three markers, with Nei's gene diversity tending to be higher for AFLPs and microsatellites in rookeries of the western and Asian stocks, while the highest mtDNA values were found in the eastern stock. Overall, and despite strongly contrasting demographic histories, after applying phylogenetic correction we found little correlation between genetic diversity and either colony size or demography. In contrast, we were able to show a highly significant positive relationship between AFLP diversity and current population size across a range of pinniped species, even though equivalent analyses did not reveal significant trends for either microsatellites or mtDNA.


Assuntos
Variação Genética , Genética Populacional , Repetições de Microssatélites , Leões-Marinhos/genética , Análise do Polimorfismo de Comprimento de Fragmentos Amplificados , Animais , Teorema de Bayes , Análise por Conglomerados , DNA Mitocondrial/genética , Marcadores Genéticos , Geografia , Modelos Genéticos , Filogenia , Densidade Demográfica , Análise de Sequência de DNA
20.
AJNR Am J Neuroradiol ; 29(8): 1561-3, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18499797

RESUMO

Esthesioneuroblastoma (ENB) is a malignant neoplasm of the olfactory epithelium. Metastasis of ENBs to retropharyngeal lymph nodes is an important finding on imaging examinations that alters staging and treatment. A total of 17 cases of ENB from 3 institutions were evaluated. The CT and MR imaging findings from the cases of 4 patients with ENB with retropharyngeal metastatic disease are reviewed. The vector of spread, staging, and treatment implications are discussed.


Assuntos
Estesioneuroblastoma Olfatório/diagnóstico , Estesioneuroblastoma Olfatório/secundário , Cavidade Nasal/diagnóstico por imagem , Cavidade Nasal/patologia , Neoplasias Nasais/diagnóstico , Faringe/diagnóstico por imagem , Faringe/patologia , Idoso , Feminino , Humanos , Metástase Linfática , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA