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1.
Lung ; 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38977494

RESUMO

INTRODUCTION: Cough is common in interstitial lung disease (ILD) and is associated with disease progression, yet its mechanisms are understudied. We investigated cough hypersensitivity features and impact in ILD. METHODS: Participants with ILD and cough (n = 195) completed a multiple choice and free text questionnaire on cough sensations/triggers and impacts. RESULTS: The majority of participants were male (54%), aged > 65 (64%), with idiopathic pulmonary fibrosis (IPF, 75%). Common cough triggers were body position (74%), physical activity (72%), and talking (62%). Common laryngeal sensations were globus (43%), and itch/tickle (42%). Cough impacted everyday life in 55%, and all activities in 31%, causing exhaustion (59%), social embarrassment (70%), urinary incontinence (46% females), and syncope/pre-syncope (12%). The total number of cough-provoking sensations/triggers correlated with impacts; ρ = 0.73, p < 0.001. CONCLUSION: Cough hypersensitivity symptoms are prevalent in ILD and detrimentally affect quality of life. Further studies investigating mechanisms of cough hypersensitivity and targeted pharmacotherapy are warranted.

2.
Phys Rev Lett ; 127(23): 235001, 2021 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-34936794

RESUMO

Understanding how atoms interact with hot dense matter is essential for astrophysical and laboratory plasmas. Interactions in high-density plasmas broaden spectral lines, providing a rare window into interactions that govern, for example, radiation transport in stars. However, up to now, spectral line-shape theories employed at least one of three common approximations: second-order Taylor treatment of broadening operator, dipole-only interactions between atom and plasma, and classical treatment of perturbing electrons. In this Letter, we remove all three approximations simultaneously for the first time and test the importance for two applications: neutral hydrogen and highly ionized magnesium and oxygen. We found 15%-50% change in the spectral line widths, which are sufficient to impact applications including white-dwarf mass determination, stellar-opacity research, and laboratory plasma diagnostics.

3.
Int J Tuberc Lung Dis ; 23(5): 555-562, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31097063

RESUMO

BACKGROUND Little is known about tuberculosis (TB) risk in the earlier stages of chronic kidney disease (CKD). OBJECTIVE To investigate the relationship between CKD at all stages and the risk of incident TB. METHODS We conducted a cohort study using 100 058 participants of a community-based health screening programme in northern Taiwan, 2005-2008. Renal function was ascertained at baseline using serum creatinine level and the urine dipstick test. The occurrence of active TB was ascertained using the National Tuberculosis Registry. Cox proportional hazards regression was used to estimate the association between CKD and TB. RESULTS During a median follow-up of 7.5 years, TB incidence was 472. In the Cox regression analyses, individuals with Stage 1-4 CKD had a 25% increase in TB hazard than those without disease (adjusted hazard ratio [aHR] 1.25, 95%CI 1.02-1.54). A positive correlation between CKD stage and TB was observed (P = 0.02 for trend). TB risk increased by 5.1% with every 10 ml/min/1.73 m² decrease in the estimated glomerular filtration rate (aHR 1.05, 95%CI 0.99-1.12). CONCLUSIONS Our results suggested an increased risk of TB in early-stage CKD. TB prevention efforts should consider individuals with earlier stages of CKD. .


Assuntos
Programas de Rastreamento , Insuficiência Renal Crônica/complicações , Tuberculose/epidemiologia , Adulto , Idoso , Estudos de Coortes , Creatinina/sangue , Progressão da Doença , Feminino , Seguimentos , Humanos , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Insuficiência Renal Crônica/fisiopatologia , Taiwan/epidemiologia , Tuberculose/etiologia
4.
Cont Lens Anterior Eye ; 41(6): 542-546, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30100388

RESUMO

This study investigated the efficacy of a novel povidone-iodine based disinfection solution for rigid gas permeable (RGP) lenses compared to three other currently available multipurpose and hydrogen peroxide solutions. Bactericidal and fungicidal activities were assessed using ISO 14729 reference methods, whilst amoebicidal properties were evaluated using an automated viability counter. All solutions were also assessed for long term storage stability over a 3-month period. The FDA guidelines were adequately achieved by all solutions tested and 3-month storage did not affect their activity against bacterial and fungal agents. Activity against Acanthamoeba castellani trophozoites reached 1-log reduction for the povidone-iodine solution and approached this level for the remaining solutions. Activity against cysts was somewhat reduced and ranged from 78 to 86% reduction in viability. A povidone-iodine based solution, which may offer advantages as resistance to this agent has not been demonstrated and it lacks toxicity, provided equivalent antimicrobial activity to other RGP solutions.


Assuntos
Bactérias/isolamento & purificação , Soluções para Lentes de Contato/farmacologia , Desinfecção/métodos , Infecções Oculares Bacterianas/prevenção & controle , Infecções Oculares Fúngicas/prevenção & controle , Fungos/isolamento & purificação , Povidona-Iodo/farmacologia , Anti-Infecciosos Locais/farmacologia , Bactérias/efeitos dos fármacos , Infecções Oculares Bacterianas/microbiologia , Infecções Oculares Fúngicas/microbiologia , Fungos/efeitos dos fármacos , Humanos
5.
Chem Sci ; 9(10): 2782-2790, 2018 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-29732064

RESUMO

Highly luminescent gold clusters simultaneously synthesized and stabilized by protein molecules represent a remarkable category of nanoscale materials with promising applications in bionanotechnology as sensors. Nevertheless, the atomic structure and luminescence mechanism of these gold clusters are still unknown after several years of developments. Herein, we report findings on the structure, luminescence and biomolecular self-assembly of gold clusters stabilized by the large globular protein, bovine serum albumin. We highlight the surprising identification of interlocked gold-thiolate rings as the main gold structural unit. Importantly, such gold clusters are in a rigidified state within the protein scaffold, offering an explanation for their highly luminescent character. Combined free-standing cluster synthesis (without protecting protein scaffold) with rigidifying and un-rigidifying experiments, were designed to further verify the luminescence mechanism and gold atomic structure within the protein. Finally, the biomolecular self-assembly process of the protein-stabilized gold clusters was elucidated by time-dependent X-ray absorption spectroscopy measurements and density functional theory calculations.

6.
J Pediatr Urol ; 14(1): 42-46, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29150195

RESUMO

INTRODUCTION: Pre-operative physical examination of male epispadias allows for classification of epispadias level as glanular (GE), penile (PE) or penopubic (PPE), and for delineation of anatomic anomalies. The incidence of associated extragenital abnormalities, such as vesicoureteral reflux (VUR), bladder neck (BN) abnormality and abnormal pubic diastasis (PD), and their impact on urinary continence has not yet been systematically studied. OBJECTIVE: The goal of this study was to evaluate whether the more proximal level of epispadias correlated with associated extragenital anatomic anomalies seen on initial imaging or endoscopic evaluation, and whether these pre-operative findings contributed to subsequent surgical management and impacted on achieving urinary continence. It was hypothesized that the more severe forms of epispadias may be associated with a higher frequency of associated anomalies. STUDY DESIGN: The study was an IRB-approved, retrospective case study of all male patients treated initially for isolated epispadias at the current institution between 1994 and 2011. Data collection was achieved by chart and radiology review evaluating PD, BN appearance, presence of VUR, surgical treatment, and urinary continence. RESULTS: A total of 26 patients were identified and divided into three groups based on appearance at physical examination: four glanular (GE), eight penile (PE), and 14 penopubic (PPE); 17 patients had an abnormal BN. Reflux was noted in nine of 20 patients who had a voiding cystourethrogram (VCUG), two of which had an episode of pyelonephritis. Of the 22 patients past the age of toilet training, 17 were continent (64% (9/14) penopubic, 63% (5/8) penile, and 75% (3/4) glanular). DISCUSSION: Anatomic classification for male epispadias did not provide sufficient information regarding extragenital findings. This study provided new information regarding PD, BN appearance, presence of reflux, and ultimate urinary continence. Pubic diastasis and BN abnormalities were more frequently seen in more severe forms of epispadias, whereas VUR seemed more prevalent in less severe forms. A template for pre-operative evaluation was outlined. Limitations of the study were its retrospective design and relatively small cohort of patients, which reflected the rarity of the condition. CONCLUSION: Based on the information generated, additional anatomic information was generated regarding boys with epispadias. This information will help guide the evaluation and the management of these patients in the future.


Assuntos
Epispadia/diagnóstico , Epispadia/cirurgia , Qualidade de Vida , Incontinência Urinária/cirurgia , Procedimentos Cirúrgicos Urológicos/métodos , Criança , Pré-Escolar , Estudos de Coortes , Bases de Dados Factuais , Epispadia/psicologia , Humanos , Lactente , Imageamento por Ressonância Magnética/métodos , Masculino , Cuidados Pré-Operatórios/métodos , Prognóstico , Procedimentos de Cirurgia Plástica/métodos , Estudos Retrospectivos , Medição de Risco , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios X/métodos , Resultado do Tratamento , Uretra/anormalidades , Uretra/cirurgia , Incontinência Urinária/diagnóstico , Incontinência Urinária/etiologia
7.
Cont Lens Anterior Eye ; 40(2): 82-87, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28038841

RESUMO

PURPOSE: To evaluate and compare changes in axial elongation, over a 14-month period, in subjects who discontinued and then resumed ortho-k lens wear with those who continued to wear their lenses or spectacles following a 2-year myopia control study. METHOD: This single masked, prospective study recruited subjects who had just completed a 2-year myopia control study. Ortho-k subjects were classified as Group OKc, in which subjects continued ortho-k lens wear for the duration of the study; or Group OKd in which subjects discontinued lens wear for seven months and wore single-vision spectacles (Phase I) and then resumed ortho-k lens wear for another seven months (Phase II). Spectacle-wearing control subjects from the initial myopia control study continued wearing spectacles as control subjects. Axial lengths were measured at scheduled visits using the IOLMaster. RESULTS: Thirteen, 16, and 15 Control, OKc, and OKd subjects, aged 8-14 years, respectively completed the study. Significant increase in axial elongation was found in OKd subjects only in Phase I but not in Phase II. On resuming lens wear, in Phase II, the rate of axial elongation was no longer significantly different from those of the Control or OKc subjects. CONCLUSION: Stopping ortho-k lens wear at or before the age of 14 years led to a more rapid increase in axial length; comparable to those wearing spectacles during the initial 2-year myopia control study, but greater than the Control and OKc group in this study. Axial elongation slowed again with resumed lens wear after six months.


Assuntos
Comprimento Axial do Olho/fisiopatologia , Miopia/terapia , Procedimentos Ortoceratológicos , Suspensão de Tratamento , Adolescente , Criança , Lentes de Contato , Óculos , Feminino , Humanos , Masculino , Miopia/fisiopatologia , Estudos Prospectivos , Método Simples-Cego
8.
J Pediatr Urol ; 12(5): 313.e1-313.e2, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27687533

RESUMO

INTRODUCTION: Bladder augmentation is a common surgical intervention for neuropathic bladder dysfunction, and has conventionally been an open procedure. We present a robotic ileocystoplasty to demonstrate the feasibility of an entirely intracorporeal approach in a pediatric patient. METHODS: The patient was a 6 year old (18.5 kg) boy with a neurogenic bladder secondary to lumbar myelomeningocele. Urodynamics revealed a small capacity and poorly compliant bladder and he was incontinent between frequent catheterizations. A robotic augmentation cystoplasty was performed. RESULTS: At one-month postoperatively, a cystogram revealed no urine leak, and the suprapubic tube was removed. The patient resumed CIC every 3 h during the day and once overnight until postoperative urodynamic studies confirmed safe dynamics, after which the CIC interval was lengthened. CONCLUSION: Robotic bladder augmentation is safe and feasible in a select pediatric population. The entire procedure including preparation of the bowel segment can be completed intracorporeally, even in smaller children.


Assuntos
Laparoscopia , Procedimentos Cirúrgicos Robóticos , Bexiga Urinaria Neurogênica/cirurgia , Bexiga Urinária/cirurgia , Criança , Humanos , Masculino , Procedimentos Cirúrgicos Urológicos/métodos
9.
J Pediatr Urol ; 12(3): 158.e1-7, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26897325

RESUMO

BACKGROUND: Sacral agenesis (SA) is a rare congenital condition that refers to the absence of part or all of two or more lower sacral vertebral bodies. It can be associated with neurogenic bladder dysfunction that does not necessarily correlate with the level of spinal or skeletal defect. Patients with SA should undergo urodynamic studies (UDS) to guide lower urinary tract (LUT) management. OBJECTIVE: This review aimed to update the present institutional experience since 1981 of this rare patient population with detailed, long-term follow-up of bladder and kidney function. STUDY DESIGN: A single institution, retrospective, IRB-approved review was performed on patients born after January 1, 1981 with an isolated diagnosis of sacral agenesis without spina bifida, and followed with urologic involvement at Boston Children's Hospital. Records were reviewed for demographics, radiologic imaging, UDS including cystometrogram (CMG) and electromyography (EMG), surgery, and blood chemistries. Comparisons were made between groups of patients based on age at diagnosis, with specific focus on renal function and stability of neurogenic bladder lesion. RESULTS: Forty-three patients were identified: 23 female and 20 male. Thirty-seven children (86%) had a known age of diagnosis. Nineteen were diagnosed before 2 months old, including five who were diagnosed prenatally, 11 were diagnosed between 2 and 18 months, and seven were diagnosed after 18 months. All 43 had UDS, with 24 (55.8%) studied at the time of diagnosis (Summary Table). Twenty had serial full UDS, with 30% demonstrating neurourologic instability. None developed end-stage renal disease (ESRD) or required spinal cord detethering. DISCUSSION: Many children with SA appeared to be diagnosed prenatally or early in life; SA was mostly identified during evaluation of associated anomalies. Though UDS aid in urologic management, testing was not routinely utilized at the time of diagnosis. CONCLUSIONS: This review of long-term follow-up in SA patients showed stable LUT and renal function, with minimal risk of progression to ESRD.


Assuntos
Anormalidades Múltiplas/fisiopatologia , Rim/fisiopatologia , Meningocele/complicações , Meningocele/fisiopatologia , Região Sacrococcígea/anormalidades , Bexiga Urinaria Neurogênica/etiologia , Bexiga Urinaria Neurogênica/fisiopatologia , Bexiga Urinária/fisiopatologia , Feminino , Humanos , Lactente , Masculino , Estudos Retrospectivos , Região Sacrococcígea/fisiopatologia , Fatores de Tempo , Resultado do Tratamento , Bexiga Urinaria Neurogênica/cirurgia
11.
Int J Organ Transplant Med ; 6(4): 141-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26576259

RESUMO

BACKGROUND: There are over 250 kidney transplant programs in the USA. OBJECTIVE: To determine if highly competitive regions, defined as regions with a higher number of transplant centers, will approve and wait-list more end-stage renal disease (ESRD) candidates for transplant despite consistent incidence and prevalence of ESRD nationwide. METHODS: ESRD Network and OPTN data completed in 2011 were obtained from all transplant centers including listing data, market saturation, market share, organs transplanted, and ESRD prevalence. Herfindahl-Hirschman Index (HHI) was used to measure the size of firms in relation to the industry to determine the amount of competition. RESULTS: States were separated into 3 groups (HHI<1000 considered competitive; HHI 1000-1800 considered moderate competition; and HHI>1800 considered highly concentrated). The percentage of ESRD patients listed in competitive, moderate, and highly concentrated regions were 19.73%, 17.02%, and 13.75%, respectively. The ESRD listing difference between competitive versus highly concentrated was significant (p<0.05). CONCLUSION: When there is strong competition without a dominant center as defined by the HHI, the entire state tends to list more patients for transplant to drive up their own center's market share. Our analysis of the available national data suggests a discrepancy in access for ESRD patient to transplantation due to transplant center competition.

12.
Nature ; 525(7568): 201-5, 2015 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-26331545

RESUMO

The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.


Assuntos
Florestas , Mapeamento Geográfico , Árvores/crescimento & desenvolvimento , Ecologia/estatística & dados numéricos , Ecossistema , Agricultura Florestal/estatística & dados numéricos , Densidade Demográfica , Reprodutibilidade dos Testes
13.
Genes Immun ; 14(4): 199-211, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23466493

RESUMO

Significant variability in cytokine and chemokine expression after Toll-like receptor (TLR) stimulation has been observed between individuals. In this study, we determined the immunophenotypic variation in a cohort of 152 neonates associated with specific single-nucleotide polymorphisms (SNPs). We identified 23 SNPs in 12 genes of the innate immune system to be significantly associated with differential cytokine and chemokine production. SNPs in three gene families, namely STAT, IRF and SYK, accounted for most associations. These gene families are important signaling components of the innate anti-viral response. A potentially damaging non-synonymous SNP in the TLR3 gene (rs3775291) associated with significant differences in expression of interferon-γ after stimulation with the synthetic TLR3 ligand, poly (I:C). Additionally, a general increase in cytokine production was observed in subjects of Asian descent. This observation could be associated with differences in SNP genotype distribution between racial groups in our cohort. Taken together, our data suggest that particular aspects of the newborn innate response to TLR stimulation are closely associated with genetic variation. These findings provide the basis for detailed molecular dissection of cause-effect relationships between genotype and immune responses, and may account for inter-individual differences in response to vaccination and risk for infection and autoimmune disease.


Assuntos
Citocinas/sangue , Imunidade Inata/genética , Recém-Nascido/imunologia , Polimorfismo de Nucleotídeo Único , Receptor 4 Toll-Like/metabolismo , Povo Asiático/genética , Feminino , Estudos de Associação Genética , Humanos , Fatores Reguladores de Interferon/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Masculino , Proteínas Tirosina Quinases/genética , Fatores de Transcrição STAT/genética , Quinase Syk , Receptor 3 Toll-Like/genética
14.
Cont Lens Anterior Eye ; 36(1): 4-12, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23116923

RESUMO

As the literature has described the increasing penetration of DDSL into the contact lens market worldwide, this review aimed to describe the development of this modality as a solution to the problems experienced with other types of contact lenses. The advantages of DDSL in comparison to reusable lenses are discussed. The important role of the practitioner in prescribing for and managing patients using this lens type are also examined, in particular with respect to non-compliance. Problems with the use of this lens type and possible solutions are explored and new applications and future development in this field are described.


Assuntos
Lentes de Contato Hidrofílicas/normas , Equipamentos Descartáveis , Optometria/normas , Cooperação do Paciente , Padrões de Prática Médica , Desenho de Equipamento , Humanos , Inquéritos e Questionários
15.
Waste Manag ; 30(7): 1273-9, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19850462

RESUMO

The incineration of MSW in fluidized beds is a commonly applied waste management practice. The composition of the ashes produced in a fluidized bed boiler has important environmental implications as potentially toxic trace elements may be associated with ash particles and it is therefore essential to determine the mechanisms controlling the association of trace elements to ash particles, including the role of major element composition. The research presented here uses micro-analytical techniques to study the distribution of major and trace elements and determine the importance of affinity-based binding mechanisms in separate cyclone ash particles from MSW combustion. Particle size and the occurrence of Ca and Fe were found to be important factors for the binding of trace elements to ash particles, but the binding largely depends on random associations based on the presence of a particle when trace elements condensate in the flue gas.


Assuntos
Incineração , Oligoelementos/análise , Resíduos/análise , Cálcio/análise , Cidades , Ferro/análise , Tamanho da Partícula , Oligoelementos/química
16.
Med Phys ; 35(7Part3): 3417, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28512893

RESUMO

Low dose-rate permanent implant brachytherapy is widely used in the management of patients with early stage prostate cancer. An assessment of the implant quality is usually carried out 30 days after the implant is delivered, using computed tomography (CT) to identify the prostate and seeds. This is difficult due to poor contrast of the prostate and the superposition of seeds in the CT images. Magnetic resonance (MR) imaging offers superior contrast but inferior visualization of seeds. At our centre, patients are imaged using both CT and T2 weighted MR 30 days after an implant, and the image sets are fused using a commercial software package. The seeds are identified on CT and the prostate volumes are contoured on MR, with fusion performed by matching seeds on CT with seed signal voids on MR. The purpose of this study was to compare standard prostate post-implant dosimetric parameters (D90, V100, etc.) for prostates contoured on CT alone (MR blinded) versus MR/CT fusion. 25 patients were evaluated with all contouring performed by the same physician. We found that the prostate volume was overestimated using CT alone as compared to MR/CT fusion (mean: 37.2cc vs. 35.0cc respectively, p = 0.033). We also found that dosimetric parameters were underestimated for CT alone compared to MR/CT fusion, including D90 (mean: 144.3Gy vs. 150.8Gy respectively, p = 0.005) and V100 (mean: 89.2% vs. 91.0% respectively, p = 0.01). Centres using CT alone for post-implant dosimetry may therefore be underestimating their implant quality.

17.
Ophthalmic Physiol Opt ; 27(1): 11-21, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17239186

RESUMO

PURPOSE: This study aimed to examine the rates of microbial contamination, and identify contaminants associated with contact lenses and lens care accessories used by a group of young contact lens wearers. METHODS: Collected contact lenses, lens cases, and lens care solutions were studied by bacterial culture. Contamination rates of these samples were recorded and compared with those reported in previous studies. RESULTS: Of the samples tested, 9% of lens extracts, 34% of case extracts and 11% of solution samples were contaminated with ocular pathogenic microorganisms. Serratia spp., Staphylococcus aureus and coagulase-negative staphylococci were the most common microorganisms isolated. Lens cases were the most frequently contaminated item. Lens cases also yielded the widest range of bacterial isolates. Contact lenses used by occasional wearers were associated with a higher contamination rate. Using either saline or multipurpose solution to rinse lenses before use appeared to be effective in reducing incidence of contamination. CONCLUSION: Our findings demonstrate that contact lenses and lens care accessories are not well maintained by contact lens wearers. Regular reviews and reinforcement of lens care procedures for the usage and care of contact lenses and lens care accessories is therefore important and essential.


Assuntos
Lentes de Contato/microbiologia , Contaminação de Equipamentos , Serratia/isolamento & purificação , Staphylococcus aureus/isolamento & purificação , Soluções para Lentes de Contato , Hong Kong , Humanos , Estudantes
18.
Biochem Soc Trans ; 33(Pt 6): 1544-6, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16246166

RESUMO

Translational control is a key genetic regulatory mechanism underlying the initial establishment of the major spatial axes of the Drosophila embryo. Many translational control mechanisms target eIF4E (eukaryotic initiation factor 4E), an initiation factor that recognizes the 5'-cap structure of the mRNA. Cap recognition by eIF4E, in complex with eIF4G, is essential for recruitment of the mRNA to the small ribosomal subunit. One established mechanism for repressing translation involves eIF4E-binding proteins, which competitively inhibit the eIF4E-eIF4G interaction. Our group has uncovered a novel mechanism for repression in which an eIF4E cognate protein called d4EHP, which cannot bind eIF4G, binds to the 5'-cap structure of cad mRNA thus rendering it translationally inactive. These two related, but distinct, mechanisms are discussed and contrasted in this review.


Assuntos
Drosophila melanogaster/genética , Regulação da Expressão Gênica , Biossíntese de Proteínas , Capuzes de RNA/metabolismo , RNA Mensageiro/metabolismo , Animais , Proteínas de Drosophila/metabolismo , Fator de Iniciação 4E em Eucariotos/metabolismo , Fator de Iniciação Eucariótico 4G/metabolismo , Ligação Proteica , Proteínas de Ligação a RNA/metabolismo
19.
Br J Radiol ; 78(928): 316-27, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15774592

RESUMO

An algorithm is described, based on ray-tracing and the beam's-eye-view, that exhaustively searches all permitted beam directions. The evaluation of the search is based on a general cost function that can be adapted to the clinical objectives by means of parameters and weighting factors. The approach takes into account the constraints of the linear accelerator by discarding beam directions that are not permitted. A sensitivity analysis was carried out to determine appropriate parameters for different sized organs, and a prostate case was used to benchmark the approach. The algorithm was also applied to two clinical cases (brain and sinus) to test the benefits of the approach compared with manual angle selection. The time to perform a beam direction search was approximately 2 min for the coplanar and 12 min for the non-coplanar beam space. The angles obtained for the prostate case compared well with reports in the literature. For the brain case, the mean dose to the right and left optic nerves was reduced by 12% and 50%, respectively, whilst the target dose uniformity was improved. For the sinus case, the mean doses to the right and left parotid glands were reduced by 54% and 46%, respectively, to the right and left optic nerves by 37% and 62%, respectively, and to the optic chiasm by 39%, whilst the target dose uniformity was also improved. For the clinical cases the plans based on optimized beam directions were simpler and resulted in better sparing of critical structures compared with plans based on manual angle selection. The approach provides a practical alternative to elaborate and time consuming beam angle optimization schemes and is suitable for routine clinical usage.


Assuntos
Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodos , Adenocarcinoma/radioterapia , Algoritmos , Criança , Humanos , Masculino , Neoplasias Meníngeas/radioterapia , Meningioma/radioterapia , Neoplasias da Próstata/radioterapia
20.
J Appl Clin Med Phys ; 4(4): 274-81, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-14604416

RESUMO

Irradiation of the cranio-spinal axis is often one of the treatment modalities of certain childhood cancers, e.g., medulloblastoma. In order to achieve a uniform dose to the spinal cord, missing tissue compensators are required. In the past, our practice was to fabricate compensators out of strips of lead. We report on the use of intensity modulated fields to achieve the desired compensation. Seven cases of pediatric cancer whose treatment involved irradiation of the cranio-spinal axis had compensators designed using a beam intensity modulation method rather than making mechanical compensators. The compensators only adjusted for missing tissue along the spinal axis. Comparisons between calculated and measured doses were made at depth in phantoms and on the surface of the patient. The intensity modulated fields were delivered using a step-and-shoot delivery on an Elekta SL20 accelerator equipped with multileaf collimator. The intensity-modulated compensators provided more flexibility in design than the physical compensator method. Finer intensity steps were achievable, more accurate dose distributions were able to be calculated, and adjustments during treatment, e.g., junction changes, were more easily implemented. Convolution/superposition dose calculations were within +/-3% of measurements. Intensity modulated fields are a practical and more efficient method of delivering uniform doses to the spine in pediatric cancer treatments. They provide many advantages over mechanical compensators with regard to time and flexibility.


Assuntos
Planejamento da Radioterapia Assistida por Computador/métodos , Planejamento da Radioterapia Assistida por Computador/tendências , Radioterapia Conformacional/métodos , Coluna Vertebral/efeitos da radiação , Algoritmos , Neoplasias Cerebelares/radioterapia , Criança , Relação Dose-Resposta à Radiação , Humanos , Meduloblastoma/radioterapia , Imagens de Fantasmas , Dosagem Radioterapêutica , Radioterapia Assistida por Computador/métodos , Radioterapia de Alta Energia/métodos
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