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1.
Breast J ; 2022: 1863519, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35711886

RESUMO

Background: The rate of inpatient mastectomies remains high despite multiple studies reporting favourably on outpatient mastectomies. Outpatient mastectomies do not compromise quality of patient care and are more efficient than inpatient care. The objective of this study was to evaluate the feasibility of outpatient mastectomy. Materials and Methods: Implementation of an outpatient mastectomy program was evaluated in a retrospective study. All patients who underwent mastectomy between January 2019 and September 2021 were included. Results: 213 patients were enrolled in the study: 62.4% (n = 133) outpatient mastectomies versus 37.6% (n = 80) inpatient mastectomies. A steady rise in outpatient mastectomies was observed over time. The second quarter of 2020, coinciding with the first COVID-19 wave, showed a peak in outpatient mastectomies. The only significant barrier to outpatient mastectomy proved to be bilateral mastectomy. Unplanned return to care was observed in 27.8% of the outpatient versus 36.3% of the inpatient mastectomies (P=0.198); the reason for unplanned return of care was similar in both groups. Conclusions: Outpatient mastectomy is shown to be feasible and safe with a steady increase during the study period. A barrier to outpatient mastectomy was bilateral mastectomy. Incidence of unplanned return to care or complications did not differ significantly between the outpatient and inpatient cohorts.


Assuntos
Neoplasias da Mama , COVID-19 , Neoplasias da Mama/cirurgia , Feminino , Humanos , Mastectomia , Pacientes Ambulatoriais , Estudos Retrospectivos
2.
Artigo em Inglês | MEDLINE | ID: mdl-33935382

RESUMO

RadiaBeam has developed a 6 MeV accelerator that is compact and light enough to be placed on a robotic arm or light truck. The main drivers of size and weight in conventional accelerators are the power source and the shielding. Small dimensions are enabled by operation at 9.3 GHz frequency (X-band), which allows reducing the size and weight of all accelerator components. Thanks to the robust design of the accelerating structure, the accelerator can be used as a source for novel cargo inspection and radiotherapy techniques. In this paper, we present the linac design and its components, as well the results of the experimental demonstration of beam acceleration.

3.
Entropy (Basel) ; 22(8)2020 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-33286677

RESUMO

The first paper published as Finite-Time Thermodynamics is from 1977 [...].

4.
Nutr Metab Cardiovasc Dis ; 29(2): 127-134, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30642793

RESUMO

BACKGROUND AND AIMS: Epidemiological investigations include dietary intakes as primary exposures or potential confounders. To reduce bias, data collection protocols include the administration of questionnaires together with measurements of biomarkers. Some error, however, remains and needs to be considered in the analysis and interpretation of results. The European Food Safety Authority supported a ring-trial to compare the precision and reproducibility of dietary assessment methods applied in Europe. METHODS AND RESULTS: Software applications used to collect 24-hour recalls and food records in six countries (Estonia, Italy, Latvia, Portugal, Spain, and Sweden) were assessed. The intake of 256 foods was identically reported to each method. Experienced interviewers participated and were instructed to repeat national protocols closely. The error in recording quantities, compared with reference values, was variable but in about 60% of recorded quantities was in the range of ±20%. Errors were however unsystematic and independent of the food type or quantification method used - although food pictures performed better. The reproducibility of some tools was limited. The methods generally captured additional ingredients (usually flavoring agents), but not sweetening agents or fortification and failed to record packaging information in about 60% of the cases. CONCLUSION: In a design that eliminated respondent bias, this study indicates that softwares, supporting databases and interviewers generally introduce random error in dietary assessments. The inclusion of large sample sizes and food pictures to quantify portions, together with enhanced attention on interviewers' training, standardisation of procedures and regular tool upgrades are essential in assuring a study's quality and comparability.


Assuntos
Confiabilidade dos Dados , Registros de Dieta , Dieta , Europa (Continente) , Humanos , Entrevistas como Assunto , Ensaio de Proficiência Laboratorial , Rememoração Mental , Tamanho da Porção , Reprodutibilidade dos Testes , Autorrelato , Software , Fatores de Tempo
5.
BMC Cancer ; 18(1): 892, 2018 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-30217171

RESUMO

BACKGROUND: Frailty is an indicator of physiological reserve in older people. In non-cancer settings, frailty indices are reliable predictors of adverse health outcomes. The aims of this study were to 1) derive and validate a frailty index (FI) from comprehensive geriatric assessment (CGA) data obtained in the solid tumour chemotherapy setting, and 2) to explore whether the FI-CGA could predict chemotherapy decisions and survival in older cancer patients with solid tumours. METHODS: Prospective cohort study of a consecutive series sample of 175 cancer patients aged 65 and older with solid tumours. A frailty index was calculated using an accumulated deficits model, coding items from the comprehensive geriatric assessment tool administered prior to chemotherapy decision-making. The domains of physical and cognitive functioning, nutrition, mood, basic and instrumental activities of daily living, and comorbidities were incorporated as deficits into the model. RESULTS: The FI-CGA had a right-skewed distribution, with median (interquartile range) of 0.27 (0.21-0.39). The 99% limit to deficit accumulation was below the theoretical maximum of 1.0, at 0.75. The FI-CGA was significantly related (p < 0.001) to vulnerability as assessed by the Vulnerable Elders Survey-13 and to medical oncologists' assessments of fitness or vulnerability to treatment. Baseline frailty as determined by the FI-CGA was also associated with treatment decisions (Treatment Terminated, Treatment Completed, No Planned Treatment) (p < 0.001), with the No Planned Treatment group significantly frailer than the other two groups. CONCLUSION: The FI-CGA is a potentially useful adjunct to cancer clinical decision-making that could predict chemotherapy outcomes in older patients with solid tumours.


Assuntos
Fragilidade/epidemiologia , Avaliação Geriátrica , Neoplasias/epidemiologia , Atividades Cotidianas , Idoso , Idoso de 80 Anos ou mais , Feminino , Idoso Fragilizado , Fragilidade/fisiopatologia , Humanos , Masculino , Neoplasias/fisiopatologia , Neoplasias/terapia
6.
MMWR Morb Mortal Wkly Rep ; 64(15): 421-3, 2015 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-25905896

RESUMO

Neural tube defects (NTDs) such as spina bifida, anencephaly, and encephalocele are serious birth defects of the brain and spine that occur during the first month of pregnancy when the neural tube fails to close completely. Randomized controlled trials and observational studies have shown that adequate daily consumption of folic acid before and during early pregnancy considerably reduces the risk for NTDs. The U.S. Public Health Service recommends that women capable of becoming pregnant consume 400 µg of folic acid daily for NTD prevention. Furthermore, fortification of staple foods (e.g., wheat flour) with folic acid has decreased folate-sensitive NTD prevalence in multiple settings and is a highly cost-effective intervention.


Assuntos
Eritrócitos/química , Ácido Fólico/sangue , Guias como Assunto , Defeitos do Tubo Neural/prevenção & controle , Organização Mundial da Saúde , Adulto , Feminino , Ácido Fólico/administração & dosagem , Alimentos Fortificados , Fidelidade a Diretrizes/estatística & dados numéricos , Humanos , Defeitos do Tubo Neural/epidemiologia , Gravidez , Estados Unidos/epidemiologia
7.
Br J Nutr ; 113(12): 1965-77, 2015 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-25917925

RESUMO

Serum and erythrocyte (RBC) total folate are indicators of folate status. No nationally representative population data exist for folate forms. We measured the serum folate forms (5-methyltetrahydrofolate (5-methylTHF), unmetabolised folic acid (UMFA), non-methyl folate (sum of tetrahydrofolate (THF), 5-formyltetrahydrofolate (5-formylTHF), 5,10-methenyltetrahydrofolate (5,10-methenylTHF)) and MeFox (5-methylTHF oxidation product)) by HPLC-MS/MS and RBC total folate by microbiologic assay in US population ≥ 1 year (n approximately 7500) participating in the National Health and Nutrition Examination Survey 2011-2. Data analysis for serum total folate was conducted including and excluding MeFox. Concentrations (geometric mean; detection rate) of 5-methylTHF (37·5 nmol/l; 100 %), UMFA (1·21 nmol/l; 99·9 %), MeFox (1·53 nmol/l; 98·8 %), and THF (1·01 nmol/l; 85·2 %) were mostly detectable. 5-FormylTHF (3·6 %) and 5,10-methenylTHF (4·4 %) were rarely detected. The biggest contributor to serum total folate was 5-methylTHF (86·7 %); UMFA (4·0 %), non-methyl folate (4·7 %) and MeFox (4·5 %) contributed smaller amounts. Age was positively related to MeFox, but showed a U-shaped pattern for other folates. We generally noted sex and race/ethnic biomarker differences and weak (Spearman's r< 0·4) but significant (P< 0·05) correlations with physiological and lifestyle variables. Fasting, kidney function, smoking and alcohol intake showed negative associations. BMI and body surface area showed positive associations with MeFox but negative associations with other folates. All biomarkers showed significantly higher concentrations with recent folic acid-containing dietary supplement use. These first-time population data for serum folate forms generally show similar associations with demographic, physiological and lifestyle variables as serum total folate. Patterns observed for MeFox may suggest altered folate metabolism dependent on biological characteristics.


Assuntos
Ácido Fólico/sangue , Inquéritos Nutricionais , Estado Nutricional , Adolescente , Adulto , Biomarcadores/sangue , Índice de Massa Corporal , Criança , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Eritrócitos/química , Etnicidade , Feminino , Humanos , Lactente , Leucovorina/sangue , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Valores de Referência , Fatores Sexuais , Espectrometria de Massas em Tandem , Tetra-Hidrofolatos/sangue , Estados Unidos/epidemiologia , Adulto Jovem
8.
Phys Chem Chem Phys ; 16(21): 9747-59, 2014 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-24401866

RESUMO

Reconciling or somehow linking the macroscopic and microscopic approaches to chemical and physical processes has been a challenge unaddressed for many years. One approach, presented here, treats the issue by examining individual phenomena well described by a macro approach that fails when applied to small systems. The key to the approach is determining the approximate system size below which the breakdown of the macro description is observable. The most developed example is the failure of the Gibbs phase rule for sufficiently small atomic clusters. Other examples, such as the onset, at sufficient size, of the insulator-to-metal transition, are discussed, as are some still more challenging phenomena.

9.
J Phys Chem A ; 117(39): 9401-3, 2013 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-23210625

RESUMO

In recent years, several theoretical studies have indicated potentially interesting, even perhaps surprising phenomena that could be observed by experiment--but have not yet been studied in the laboratory. Here we give the background and motivation for two of these, with the admitted goal of stimulating those experimental studies. The two topics: (1) the production and study of amorphous alkali metal halide clusters; (2) Penning detachment, the analogue of the well-studied Penning ionization, but in which an electron is detached from a negative ion, rather than from a neutral atom, by energy transfer in collision with an excited atom. The latter phenomenon could be particularly relevant for stellar atmospheres where negative ions are abundant. In each case, we indicate the implications and potential of having substantive experimental information about each, in effect explaining the motivation to carry out the experiments.

10.
J Chem Phys ; 139(21): 215101, 2013 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-24320403

RESUMO

A method for time series analysis of molecular dynamics simulation of a protein is presented. In this approach, wavelet analysis and principal component analysis are combined to decompose the spatio-temporal protein dynamics into contributions from a hierarchy of different time and space scales. Unlike the conventional Fourier-based approaches, the time-localized wavelet basis captures the vibrational energy transfers among the collective motions of proteins. As an illustrative vehicle, we have applied our method to a coarse-grained minimalist protein model. During the folding and unfolding transitions of the protein, vibrational energy transfers between the fast and slow time scales were observed among the large-amplitude collective coordinates while the other small-amplitude motions are regarded as thermal noise. Analysis employing a Gaussian-based measure revealed that the time scales of the energy redistribution in the subspace spanned by such large-amplitude collective coordinates are slow compared to the other small-amplitude coordinates. Future prospects of the method are discussed in detail.


Assuntos
Simulação de Dinâmica Molecular , Proteínas/química , Cinética , Conformação Proteica
11.
J Musculoskelet Neuronal Interact ; 13(1): 89-96, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23445918

RESUMO

OBJECTIVES: The purpose of this study was to determine variability in cortical volumetric bone density (vBMD) from a single slice tibia image over a range of vBMD readings and ages. METHODS: Males and females (N=80; aged 6-80) were randomly selected from a previous study. Cortical vBMD at the anterior, posterior, medial, and lateral regions as well as the endocortical, mid-cortical, and pericortical regions of the cortical shell were determined using pQCT. RESULTS: Mean anterior ROI cortical vBMD (1111±11 mg/cm(3)) was lower than the posterior and lateral ROIs (1169±7 mg/cm(3) and 1151±9 mg/cm(3), respectively), (p<0.05). Individuals with lower overall cortical vBMD and younger individuals had greater vBMD variability within the shell (r=0.37, p=0.004). Difference between anterior and posterior regions was inversely associated with cortical vBMD and jump power (r=0.46, p=0.001). Endocortical vBMD (1080±6 mg/cm) was lower than the mid-cortical and pericortical regions (1152±5 mg/cm(3) and 1147±5 mg/cm, respectively). CONCLUSIONS: Variability in cortical vBMD was higher among young individuals and those with lower overall cortical vBMD, while lowest in older individuals and men. The anterior ROI had lower mean cortical vBMD than posterior or lateral regions, and endocortical vBMD was lower than the mid- and pericortical regions.


Assuntos
Envelhecimento/fisiologia , Densidade Óssea/fisiologia , Tíbia/diagnóstico por imagem , Tíbia/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X/métodos , Adulto Jovem
12.
Nat Genet ; 10(4): 415-23, 1995 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7670491

RESUMO

Using our data set of 3,143 single pass sequences from human brain cDNA libraries, we have developed a strategy in which gene-based sequence-tagged-sites (STSs), derived from 3'untranslated regions of human cDNAs, are rapidly assigned to megabase-insert yeast artificial chromosomes and somatic cell hybrids to generate regional gene mapping data. Employing this approach, we have mapped 318 cDNAs, representing 308 human genes. Ninety-two of these mapped to regions implicated in human genetic diseases, identifying them as candidate genes. Extension of this strategy has the potential to result in virtually every human gene having, at its 3' end, its own associated STS, with each STS in turn specifying both a corresponding genomic clone and a specific regional location in the genome.


Assuntos
Mapeamento Cromossômico/métodos , Genoma Humano , Sitios de Sequências Rotuladas , Animais , Encéfalo , Cromossomos Artificiais de Levedura , Humanos , Células Híbridas , Reação em Cadeia da Polimerase , Roedores
13.
Nat Genet ; 20(2): 175-9, 1998 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9771711

RESUMO

Over 200,000 new prostate cancer cases are diagnosed in the United States each year, accounting for more than 35% of all cancer cases affecting men, and resulting in 40,000 deaths annually. Attempts to characterize genes predisposing to prostate cancer have been hampered by a high phenocopy rate, the late age of onset of the disease and, in the absence of distinguishing clinical features, the inability to stratify patients into subgroups relative to suspected genetic locus heterogeneity. We previously performed a genome-wide search for hereditary prostate cancer (HPC) genes, finding evidence of a prostate cancer susceptibility locus on chromosome 1 (termed HPC1; ref. 2). Here we present evidence for the location of a second prostate cancer susceptibility gene, which by heterogeneity estimates accounts for approximately 16% of HPC cases. This HPC locus resides on the X chromosome (Xq27-28), a finding consistent with results of previous population-based studies suggesting an X-linked mode of HPC inheritance. Linkage to Xq27-28 was observed in a combined study population of 360 prostate cancer families collected at four independent sites in North America, Finland and Sweden. A maximum two-point lod score of 4.60 was observed at DXS1113, theta=0.26, in the combined data set. Parametric multipoint and non-parametric analyses provided results consistent with the two-point analysis. Significant evidence for genetic locus heterogeneity was observed, with similar estimates of the proportion of linked families in each separate family collection. Genetic mapping of the locus represents an important initial step in the identification of an X-linked gene implicated in the aetiology of HPC.


Assuntos
Predisposição Genética para Doença/genética , Neoplasias da Próstata/genética , Cromossomo X , Adulto , Idoso , Idoso de 80 Anos ou mais , Mapeamento Cromossômico , Marcadores Genéticos , Genótipo , Humanos , Escore Lod , Masculino , Pessoa de Meia-Idade , Linhagem , Receptores Androgênicos/genética
14.
J Obstet Gynaecol ; 33(2): 165-70, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23445141

RESUMO

The aim of this study was to compare the effect of low-dose metformin and rosiglitazone on clinical, biochemical, ultrasound features and endothelial function in patients with polycystic ovary syndrome (PCOS). After randomisation, a group of 17 women received metformin 500 mg b.d. (MG) and a group of 18 received rosiglitazone 4 mg o.d. (RG) for 3 months. Serum FSH, LH, testosterone, fasting glucose, insulin, IGF-1, IGFBP-3, CRP were measured at baseline and follow-up. Ovarian scan and microcirculation studies were also performed. It was found that there was a reduction in hyperandrogenaemia, insulin resistance, lipidaemia, CRP levels, ovarian volume and number of follicles in both groups. No improvement in endothelial- dependent function was noted but a significant improvement in endothelial-independent function in rosiglitazone group. It was concluded that low-dose therapeutic regimen with rosiglitazone and metformin, has comparable beneficial impacts on metabolic, hormonal and morphological features of PCOS but no obvious effect on vascular parameters in a population of predominantly mild PCOS.


Assuntos
Hipoglicemiantes/administração & dosagem , Metformina/administração & dosagem , Síndrome do Ovário Policístico/tratamento farmacológico , Tiazolidinedionas/administração & dosagem , Adulto , Quimioterapia Combinada , Endotélio Vascular/efeitos dos fármacos , Feminino , Humanos , Ovário/diagnóstico por imagem , Ovário/efeitos dos fármacos , Síndrome do Ovário Policístico/sangue , Síndrome do Ovário Policístico/diagnóstico por imagem , Rosiglitazona , Resultado do Tratamento , Ultrassonografia
15.
Radiography (Lond) ; 29(1): 101-108, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36327514

RESUMO

INTRODUCTION: Pain and discomfort has a negative impact on a patient's overall experience and may impact on subsequent re-attendance to mammography. Pain during mammography remains a significant issue. Assessment of interventions to reduce levels of pain associated with mammography are essential to increase attendance to breast services and improve user experience. METHODS: Participants (n = 60) were invited to take part in the study at one hospital Trust within the UK. Postal invitations were sent 2 weeks prior to appointment to patients older than 40 years with previous mammography attendance at the same Trust to allow for comparison of previous and current pain scores/compression values. Patients were randomised into 3 groups: Binaural music (BM), non-binaural music (NBM) and standard care (C). A numerical rating scale (NRS) was used to rate pain. RESULTS: Patient tolerance is increased by the application of both the non-binaural and binaural music. Binaural music was most effective in improving patient tolerance (p = 0.02). When applied compression increased some patients recorded less pain, which may have implications to image quality and radiation dose for patients. Binaural music reduces the perception of mammographic pain within this data set. CONCLUSION: 5 min exposure to binaural music improves patient experience and tolerance for mammography which could be utilised to improve attendance rates in screening and symptomatic services. IMPLICATIONS FOR PRACTICE: There is an indication for further research looking at application prior and during interventional biopsies. Music intervention can be offered to patients in the severe pain category who refuse mammography. It is acknowledged from these findings that the introduction of BM and NBM prior to mammography would be a low risk, cost effective intervention within the hospital setting.


Assuntos
Música , Dor , Humanos , Dor/etiologia , Dor/prevenção & controle , Pressão , Mamografia/métodos , Mama
16.
Dev Biol ; 352(2): 288-98, 2011 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-21295565

RESUMO

A number of Wnt genes are expressed during, and are known to be essential for, early kidney development. It is typically assumed that their products will act through the canonical ß-catenin signalling pathway. We have found evidence that suggests canonical Wnt signalling is not active in the early nephrogenic metanephric mesenchyme, but instead provide expressional and functional evidence that implicates the non-canonical Calcium/NFAT Wnt signalling pathway in nephrogenesis. Members of the NFAT (Nuclear Factor Activated in T cells) transcription factor gene family are expressed throughout murine kidney morphogenesis and NFATc3 is localised to the developing nephrons. Treatment of kidney rudiments with Cyclosporin A (CSA), an inhibitor of Calcium/NFAT signalling, decreases nephron formation--a phenotype similar to that in Wnt4(-/-) embryos. Treatment of Wnt4(-/-) kidneys with Ionomycin, an activator of the pathway, partially rescues the phenotype. We propose that the non-canonical Calcium/NFAT Wnt signalling pathway plays an important role in early mammalian renal development and is required for complete MET during nephrogenesis, potentially acting downstream of Wnt4.


Assuntos
Sinalização do Cálcio/fisiologia , Rim/embriologia , Rim/metabolismo , Fatores de Transcrição NFATC/metabolismo , Animais , Sequência de Bases , Sinalização do Cálcio/efeitos dos fármacos , Ciclosporina/farmacologia , Sondas de DNA/genética , Regulação da Expressão Gênica no Desenvolvimento , Ionomicina/farmacologia , Rim/efeitos dos fármacos , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Fenótipo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Proteínas Wnt/deficiência , Proteínas Wnt/genética , Proteínas Wnt/metabolismo , Proteína Wnt4 , beta Catenina/metabolismo
17.
J Nutr ; 142(5): 886-93, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22437563

RESUMO

The NHANES has monitored folate status of the U.S. population from prefortification (1988-1994) to postfortification (1999-2010) by measuring serum and RBC folate concentrations. The Bio-Rad radioassay (BR) was used from 1988 to 2006, and the microbiologic assay (MBA) was used from 2007 to 2010. The MBA produces higher concentrations than the BR and is considered to be more accurate. Thus, to bridge assay differences and to examine folate trends over time, we adjusted the BR results to be comparable to the MBA results. Postfortification, assay-adjusted serum and RBC folate concentrations were 2.5 times and 1.5 times prefortification concentrations, respectively, and showed a significant linear trend (P < 0.001) to slightly lower concentrations during 1999-2010. The postfortification prevalence of low serum (<10 nmol/L) or RBC (<340 nmol/L) folate concentrations was ≤ 1%, regardless of demographic subgroup, compared with 24% for serum folate and 3.5% for RBC folate prefortification, with substantial variation among demographic subgroups. The central 95% reference intervals for serum and RBC folate varied by demographic subgroup during both pre- and postfortification periods. Age and dietary supplement use had the greatest effects on prevalence estimates of low folate concentrations during the prefortification period. In summary, the MBA-equivalent blood folate concentrations in the U.S. population showed first a sharp increase from pre- to postfortification, then showed a slight decrease (17% for serum and 12% for RBC folate) during the 12-y postfortification period. The MBA-equivalent pre- and postfortification reference concentrations will inform countries that plan folic acid fortification or that need to evaluate its impact.


Assuntos
Eritrócitos/metabolismo , Deficiência de Ácido Fólico , Ácido Fólico/administração & dosagem , Ácido Fólico/sangue , Alimentos Fortificados/estatística & dados numéricos , Inquéritos Nutricionais/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Deficiência de Ácido Fólico/sangue , Deficiência de Ácido Fólico/epidemiologia , Deficiência de Ácido Fólico/prevenção & controle , Humanos , Masculino , Pessoa de Meia-Idade , Morbidade/tendências , Prevalência , Estados Unidos/epidemiologia , Adulto Jovem
18.
Proc Natl Acad Sci U S A ; 106(1): 73-8, 2009 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-19114654

RESUMO

The folding energy landscape of proteins has been suggested to be funnel-like with some degree of ruggedness on the slope. How complex the landscape, however, is still rather unclear. Many experiments for globular proteins suggested relative simplicity, whereas molecular simulations of shorter peptides implied more complexity. Here, by using complete conformational sampling of 2 globular proteins, protein G and src SH3 domain and 2 related random peptides, we investigated their energy landscapes, topological properties of folding networks, and folding dynamics. The projected energy surfaces of globular proteins were funneled in the vicinity of the native but also have other quite deep, accessible minima, whereas the randomized peptides have many local basins, including some leading to seriously misfolded forms. Dynamics in the denatured part of the network exhibited basin-hopping itinerancy among many conformations, whereas the protein reached relatively well-defined final stages that led to their native states. We also found that the folding network has the hierarchic nature characterized by the scale-free and the small-world properties.


Assuntos
Simulação por Computador , Proteínas do Tecido Nervoso/química , Dobramento de Proteína , Domínios de Homologia de src , Cinética , Conformação Proteica , Termodinâmica
19.
Appl Radiat Isot ; 179: 110029, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34814009

RESUMO

Although linear accelerators are used in many security, industrial and medical applications, the existing technologies are too large and expensive for several critical applications such as radioactive source replacement, field radiography and mobile cargo scanners. One of the main requirements for these sources is to be highly portable to allow field operation. In response to this problem, RadiaBeam has designed a hand-portable 1 MeV X-ray source, scalable to higher energies, based on Ku-band split electron linac, that can be used for Ir-192 radioisotope replacement. In this paper, we present its multiphysics and engineering design studies, as well as an accelerating structure prototype along with RF measurements.


Assuntos
Radioisótopos de Irídio/química , Aceleradores de Partículas , Elétrons , Desenho de Equipamento
20.
Biophys J ; 100(9): 2302-8, 2011 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-21539800

RESUMO

Formation of amyloid oligomers, the most toxic species of amyloids in degenerative diseases, is critically coupled to the interplay with surrounding water. The hydrophobic force driving the oligomerization causes water removal from interfaces, changing the surface-hydration properties. Here, we show that such effects alter the magnetic relaxation response of local water in ways that may enable oligomer detection. By using water proton magnetic resonance spectroscopy, we measured significantly longer transverse magnetic relaxation (T(2)) times in mixtures of serum and amyloidogenic Aß(1-42) peptides versus similar concentration solutions of serum and nonamyloidogenic scrambled Aß(42-1) peptides. Immunochemistry with oligomer-specific antibodies, electron microscopy and computer simulations demonstrated that the hyperintense magnetic signal correlates with Aß(1-42) oligomerization. Finding early biophysical markers of the oligomerization process is crucial for guiding the development of new noninvasive imaging techniques, enabling timely diagnosis of amyloid-related diseases and pharmacological intervention.


Assuntos
Amiloide/química , Prótons , Água/química , Amiloide/ultraestrutura , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/ultraestrutura , Espectroscopia de Ressonância Magnética , Estrutura Quaternária de Proteína , Propriedades de Superfície , Fatores de Tempo
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