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1.
BMC Health Serv Res ; 20(1): 213, 2020 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-32171308

RESUMO

BACKGROUND: For studying the effectiveness of treatment, it is important to check whether a new treatment is performed as originally described in the study-protocol. OBJECTIVES: To evaluate whether an interdisciplinary graded exposure program, for adolescents with chronic musculoskeletal pain reporting pain-related fear, was performed according to protocol, and whether it is feasible to implement the program in rehabilitation care. METHODS: A process evaluation where quantitative and qualitative data on participant characteristics (adolescents, parents and therapists), attendance and participants' opinion on the program were collected, by means of registration forms, questionnaires and group interviews. To evaluate treatment fidelity, audio and video recordings of program sessions were analyzed. RESULTS: Thirty adolescents were offered the program, of which 23 started the program. Adolescents attended on average 90% of the sessions. At least one parent per adolescent participated in the program. Analysis of 20 randomly selected recordings of treatment sessions revealed that treatment fidelity was high, since 81% of essential treatment elements were offered to the adolescents. The program was considered client-centered by adolescents and family-centered by parents. Treatment teams wished to continue offering the program in their center. CONCLUSION: The interdisciplinary graded exposure program was performed largely according to protocol, and therapists, adolescents and their parents had a favorable opinion on the program. Implementation of the program in rehabilitation care is considered feasible. TRIAL REGISTRATION: Clinicaltrials.gov ID: NCT02181725 (7 February 2014).


Assuntos
Dor Crônica/psicologia , Dor Crônica/reabilitação , Medo , Dor Musculoesquelética/psicologia , Dor Musculoesquelética/reabilitação , Adolescente , Criança , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pais/psicologia , Avaliação de Processos em Cuidados de Saúde , Avaliação de Programas e Projetos de Saúde , Pesquisa Qualitativa , Inquéritos e Questionários
3.
Stem Cells ; 33(7): 2343-50, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25826782

RESUMO

Danon disease is a familial cardiomyopathy associated with impaired autophagy due to mutations in the gene encoding lysosomal-associated membrane protein type 2 (LAMP-2). Emerging evidence has highlighted the importance of autophagy in regulating cardiomyocyte bioenergetics, function, and survival. However, the mechanisms responsible for cellular dysfunction and death in cardiomyocytes with impaired autophagic flux remain unclear. To investigate the molecular mechanisms responsible for Danon disease, we created induced pluripotent stem cells (iPSCs) from two patients with different LAMP-2 mutations. Danon iPSC-derived cardiomyocytes (iPSC-CMs) exhibited impaired autophagic flux and key features of heart failure such as increased cell size, increased expression of natriuretic peptides, and abnormal calcium handling compared to control iPSC-CMs. Additionally, Danon iPSC-CMs demonstrated excessive amounts of mitochondrial oxidative stress and apoptosis. Using the sulfhydryl antioxidant N-acetylcysteine to scavenge free radicals resulted in a significant reduction in apoptotic cell death in Danon iPSC-CMs. In summary, we have modeled Danon disease using human iPSC-CMs from patients with mutations in LAMP-2, allowing us to gain mechanistic insight into the pathogenesis of this disease. We demonstrate that LAMP-2 deficiency leads to an impairment in autophagic flux, which results in excessive oxidative stress, and subsequent cardiomyocyte apoptosis. Scavenging excessive free radicals with antioxidants may be beneficial for patients with Danon disease. In vivo studies will be necessary to validate this new treatment strategy.


Assuntos
Doença de Depósito de Glicogênio Tipo IIb/genética , Insuficiência Cardíaca/genética , Miócitos Cardíacos/metabolismo , Estresse Oxidativo/genética , Apoptose , Autofagia , Doença de Depósito de Glicogênio Tipo IIb/patologia , Insuficiência Cardíaca/patologia , Humanos , Células-Tronco Pluripotentes Induzidas
4.
Nanotechnology ; 26(7): 074001, 2015 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-25629930

RESUMO

Graphene nanopores are receiving great attention due to their atomically thin membranes and intrinsic electrical properties that appear greatly beneficial for biosensing and DNA sequencing. Here, we present an extensive study of the low-frequency 1/f noise in the ionic current through graphene nanopores and compare it to noise levels in silicon nitride pore currents. We find that the 1/f noise magnitude is very high for graphene nanopores: typically two orders of magnitude higher than for silicon nitride pores. This is a drawback as it significantly lowers the signal-to-noise ratio in DNA translocation experiments. We evaluate possible explanations for these exceptionally high noise levels in graphene pores. From examining the noise for pores of different diameters and at various salt concentrations, we find that in contrast to silicon nitride pores, the 1/f noise in graphene pores does not follow Hooge's relation. In addition, from studying the dependence on the buffer pH, we show that the increased noise cannot be explained by charge fluctuations of chemical groups on the pore rim. Finally, we compare single and bilayer graphene to few-layer and multi-layer graphene and boron nitride (h-BN), and we find that the noise reduces with layer thickness for both materials, which suggests that mechanical fluctuations may be the underlying cause of the high 1/f noise levels in monolayer graphene nanopore devices.


Assuntos
Técnicas Biossensoriais/métodos , Grafite/química , Nanopartículas Metálicas/química , Nanoporos , Nanotecnologia/métodos , Benzofenonas , Soluções Tampão , DNA/química , Etanol/química , Análise de Fourier , Concentração de Íons de Hidrogênio , Cetonas/química , Microscopia Eletrônica de Transmissão , Polietilenoglicóis/química , Polímeros , Reprodutibilidade dos Testes , Análise de Sequência de DNA , Razão Sinal-Ruído
6.
JID Innov ; 4(4): 100286, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38994234

RESUMO

Basal cell carcinoma (BCC) is classified histologically into subtypes that determine treatment decisions. MicroRNAs (miRs) are short noncoding RNAs that may serve as diagnostic biomarkers. We investigated if particular miRs could distinguish BCC subtypes. We sequenced miRs from 55 archival BCC and 9 control skin specimens and then validated these miRs by qRT-PCR assay on a second BCC cohort (18 superficial, 16 nodular, 15 infiltrative) and control skin (n = 12). Expression values for individual miRs were normalized to miR-16-5p, which was the least variant among the control skin and BCC samples. We found that (i) miR-383-5p and miR-145-5p are downregulated in all BCC subtypes compared with control skin, (ii) miR-181c-5p is downregulated in superficial compared with invasive (nodular/infiltrative) BCC, and (iii) miR-22-5p and miR-708-5p are upregulated in infiltrative compared with superficial/nodular BCC and miR-30c-5p is downregulated in infiltrative compared with nodular BCC. Receiver operating characteristic analysis demonstrated excellent capacity of these miRs to discriminate between BCC and control skin (area under the curve, 0.94-0.98), whereas the capacity to discriminate between superficial and invasive subtypes was less robust (area under the curve, 0.7-0.8). Future prospective studies may determine the utility of these miRs as diagnostic biomarkers to guide biopsy and treatment of BCC.

7.
bioRxiv ; 2024 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-38948879

RESUMO

Acral melanoma (AM) is an aggressive melanoma variant that arises from palmar, plantar, and nail unit melanocytes. Compared to non-acral cutaneous melanoma (CM), AM is biologically distinct, has an equal incidence across genetic ancestries, typically presents in advanced stage disease, is less responsive to therapy, and has an overall worse prognosis. Independent analysis of published genomic and transcriptomic sequencing identified that receptor tyrosine kinase (RTK) ligands and adapter proteins are frequently amplified, translocated, and/or overexpressed in AM. To target these unique genetic changes, a zebrafish acral melanoma model was exposed to a panel of narrow and broad spectrum multi-RTK inhibitors, revealing that dual FGFR/VEGFR inhibitors decrease acral-analogous melanocyte proliferation and migration. The potent pan-FGFR/VEGFR inhibitor, Lenvatinib, uniformly induces tumor regression in AM patient-derived xenograft (PDX) tumors but only slows tumor growth in CM models. Unlike other multi-RTK inhibitors, Lenvatinib is not directly cytotoxic to dissociated AM PDX tumor cells and instead disrupts tumor architecture and vascular networks. Considering the great difficulty in establishing AM cell culture lines, these findings suggest that AM may be more sensitive to microenvironment perturbations than CM. In conclusion, dual FGFR/VEGFR inhibition may be a viable therapeutic strategy that targets the unique biology of AM.

8.
Development ; 137(11): 1887-96, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20460367

RESUMO

Discovering the genetic and cellular mechanisms that drive cardiac morphogenesis remains a fundamental goal, as three-dimensional architecture greatly impacts functional capacity. During development, accurately contoured chambers balloon from a primitive tube in a process characterized by regional changes in myocardial cell size and shape. How these localized changes are achieved remains elusive. Here, we show in zebrafish that microRNA-143 (miR-143) is required for chamber morphogenesis through direct repression of adducin3 (add3), which encodes an F-actin capping protein. Knockdown of miR-143 or disruption of the miR-143-add3 interaction inhibits ventricular cardiomyocyte F-actin remodeling, which blocks their normal growth and elongation and leads to ventricular collapse and decreased contractility. Using mosaic analyses, we find that miR-143 and add3 act cell-autonomously to control F-actin dynamics and cell morphology. As proper chamber emergence relies on precise control of cytoskeletal polymerization, Add3 represents an attractive target to be fine-tuned by both uniform signals, such as miR-143, and undiscovered localized signals. Together, our data uncover the miR-143-add3 genetic pathway as essential for cardiac chamber formation and function through active adjustment of myocardial cell morphology.


Assuntos
Proteínas de Ligação a Calmodulina/genética , Coração/embriologia , MicroRNAs/genética , Proteínas de Peixe-Zebra/genética , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Regiões 3' não Traduzidas , Actinas/metabolismo , Animais , Sequência de Bases , Proteínas de Ligação a Calmodulina/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Hibridização In Situ , Miócitos Cardíacos/citologia , Miócitos Cardíacos/fisiologia , Oligodesoxirribonucleotídeos Antissenso/genética , Homologia de Sequência do Ácido Nucleico , Peixe-Zebra/fisiologia , Proteínas de Peixe-Zebra/fisiologia
9.
Nucleic Acids Res ; 39(15): 6558-67, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21576230

RESUMO

Homologous recombination is essential for the preservation of genome stability, thereby preventing cancer. The recombination protein RAD51 drives DNA strand exchange, which requires the assembly, rearrangement and disassembly of a RAD51 filament on DNA, coupled to ATP binding and hydrolysis. This process is facilitated and controlled by recombination mediators and accessory factors. Here, we have employed a range of single molecule techniques to determine the influence of the C-terminal RAD51 interaction domain (CTRD) of the breast cancer tumor suppressor BRCA2 on intrinsic aspects of RAD51-DNA interactions. We show that at high concentration the CTRD entangles RAD51 filaments and reduces RAD51 filament formation in a concentration dependent manner. It does not affect the rate of filament disassembly measured as the loss of fluorescent signal due to intrinsic RAD51 protein dissociation from double-stranded DNA (dsDNA). We conclude that, outside the context of the full-length protein, the CTRD does not reduce RAD51 dissociation kinetics, but instead hinders filament formation on dsDNA. The CTRDs mode of action is most likely sequestration of multiple RAD51 molecules thereby rendering them inactive for filament formation on dsDNA.


Assuntos
Proteína BRCA2/metabolismo , Rad51 Recombinase/metabolismo , Proteína BRCA2/química , DNA/metabolismo , Cinética , Microscopia de Força Atômica , Microscopia de Fluorescência , Domínios e Motivos de Interação entre Proteínas , Rad51 Recombinase/análise , Rad51 Recombinase/química
10.
Breast Cancer Res Treat ; 134(1): 253-8, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22434527

RESUMO

Being recalled for further diagnostic procedures after an abnormal screening mammogram (ASM) can evoke a high state anxiety with lowered quality of life (QoL). We examined whether these adverse psychological consequences are found in all women with benign breast disease (BBD) or are particular to women referred after ASM. In addition, the influence of the anxiety as a personality characteristic (trait anxiety) was studied. Between September 2002 and February 2010 we performed a prospective longitudinal study in six Dutch hospitals. Women referred after ASM or with a palpable lump in the breast (PL), who were subsequently diagnosed with BBD, were included. Before diagnosis (at referral) and during follow-up, questionnaires were completed examining trait anxiety (at referral), state anxiety, depressive symptoms (at referral, one, three and 6 months after diagnosis), and QoL (at referral and 12 months). Women referred after ASM (N=363) were compared with women with PL (N=401). A similar state anxiety score was found in both groups, but a lower psychological QoL score at 12 months was seen in the ASM group. In women with not-high trait anxiety those in the ASM group were more anxious with more depressive symptoms at referral, and reported impaired psychological QoL at referral and at 12 months compared with the PL group. No differences were found between ASM and PL in women with high trait anxiety, but this group scored unfavorably on anxiety, depressive symptoms and QoL compared with women with not-high trait anxiety. ASM evokes more anxiety and depressive symptoms and lowered QoL compared with women referred with PL, especially in women who are not prone to anxiety. Women should be fully informed properly about the risks and benefits of breast cancer screening programs. We recommend identifying women at risk of reduced QoL using a psychometric test.


Assuntos
Ansiedade , Doenças Mamárias/diagnóstico por imagem , Detecção Precoce de Câncer/psicologia , Adulto , Doenças Mamárias/psicologia , Depressão , Feminino , Humanos , Pessoa de Meia-Idade , Palpação , Estudos Prospectivos , Qualidade de Vida , Radiografia , Inquéritos e Questionários
11.
Case Rep Dermatol Med ; 2022: 2598965, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36386569

RESUMO

This study describes a case of amelanotic lentigo maligna melanoma in a 69-year-old female that had been growing for approximately 5 years. The asymptomatic lesion had been previously diagnosed and treated as a fungal skin infection, an inflammatory rash, and an actinic keratosis that did not respond to standard treatments. Biopsy revealed confluent and nested atypical melanocytes at the dermal-epidermal junction, consistent with melanoma in situ. Excisional biopsy revealed invasive lentigo maligna melanoma, Breslow depth 0.3 mm, with positive melanoma in situ at margins. She is now 3 years post-Mohs surgery without recurrence. When working up a patient with a hypopigmented or inflammatory lesion not responding to standard therapies, physicians should always consider biopsy to rule out unusual neoplastic etiologies, such as amelanotic melanomas.

12.
Int J Food Microbiol ; 370: 109638, 2022 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-35378381

RESUMO

Thermal inactivation of pathogenic and spoilage organisms in low and intermediate moisture foods is of critical importance for guaranteeing microbiological safety and stability of these products. Producers tendentially reduce salt in low and intermediate moisture foods because of nutritional health considerations, but it is unclear how this affects microbial inactivation rates during pasteurization. In this study we predict the time to achieve a pre-defined 6-log reduction for Salmonella enterica subsp. enterica serovar Napoli (hereafter: S. Napoli) and Eurotium herbariorum mould spores (hereafter: E. herbariorum spores) and the relationship with product characteristics. We tested 31 design products for heat inactivation of S. Napoli and 29 design products for heat inactivation of E. herbariorum spores. We used a global Bayesian regression combining primary Weibull models with a secondary regression model to relate pasteurization temperature and product characteristics (water activity (aw), pH, and fractions of sodium chloride, sucrose and oil on product) to microbial counts. With this model, we predict the time to 6-log reduction. Thermal inactivation rates were much higher for vegetative S. Napoli than for E. herbariorum spores. Also, inactivation curves were non-linear for many experiments. There were significant associations between the Weibull model parameters and temperature, and pH and aw for S. Napoli and E. herbariorum spores, respectively. We parameterized an inactivation model for S. Napoli and E. herbariorum spores using design products with a broad range of characteristics and showed how the simplified approach of using D-values does not accurately describe the non-linearity of thermal inactivation for both types of organism. Results of our model can be used to produce accurate heat inactivation predictions as input for the pasteurization process in factories where intermediate moisture foods are manufactured.


Assuntos
Microbiologia de Alimentos , Temperatura Alta , Aspergillus , Teorema de Bayes , Contagem de Colônia Microbiana , Salmonella/fisiologia , Esporos Fúngicos
13.
Br J Surg ; 98(4): 537-42, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21656719

RESUMO

BACKGROUND: Screening for breast cancer reduces breast cancer-related mortality. Advantages of screening are explained clearly, but its disadvantages are underrepresented in consent folders. METHODS: In September 2002 a prospective, longitudinal study started concerning quality of life (QoL) in women with breast disease. Between September 2002 and January 2007, 385 women with an abnormal screening mammogram were included. Of these, 152 women were diagnosed with breast cancer (BC group) and 233 had a false-positive result (FP group). Questionnaires concerning anxiety (State and Trait Anxiety Inventory) and QoL (World Health Organization Quality of Life assessment instrument 100) were completed before diagnosis, and 1, 3, 6 and 12 months later. RESULTS: The BC group was significantly older (60.2 versus 57.3 years; P < 0.001); significantly more histological biopsies were needed in the FP group (P < 0.001). Almost 60 per cent of the FP group revisited the outpatient clinic in the first year. Trait anxiety had a profound influence on QoL. Women in the FP group with a high score on trait anxiety had lowest QoL on all measurements (P < 0.001). They also reported more feelings of anxiety compared with women in the FP group with a lower trait anxiety score, and women in the BC group with a low trait anxiety score (P < 0.001). CONCLUSION: Women with a false-positive diagnosis of screen-detected breast cancer had a low QoL and feelings of anxiety, especially when they scored high on trait anxiety. This effect lasted for at least 1 year.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Mamografia/métodos , Qualidade de Vida , Idoso , Análise de Variância , Ansiedade/etiologia , Neoplasias da Mama/psicologia , Detecção Precoce de Câncer , Feminino , Humanos , Mamografia/psicologia , Pessoa de Meia-Idade , Personalidade , Fatores de Risco
14.
Proc Natl Acad Sci U S A ; 105(2): 417-21, 2008 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-18184817

RESUMO

We study ionic current fluctuations in solid-state nanopores over a wide frequency range and present a complete description of the noise characteristics. At low frequencies (f approximately < 100 Hz) we observe 1/f-type of noise. We analyze this low-frequency noise at different salt concentrations and find that the noise power remarkably scales linearly with the inverse number of charge carriers, in agreement with Hooge's relation. We find a Hooge parameter alpha = (1.1 +/- 0.1) x 10(-4). In the high-frequency regime (f approximately > 1 kHz), we can model the increase in current power spectral density with frequency through a calculation of the Johnson noise. Finally, we use these results to compute the signal-to-noise ratio for DNA translocation for different salt concentrations and nanopore diameters, yielding the parameters for optimal detection efficiency.


Assuntos
Íons , Nanopartículas/química , Nanotecnologia/métodos , Algoritmos , Transporte Biológico , DNA/química , DNA/metabolismo , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Transmissão , Modelos Químicos , Oxigênio/química , RNA/química , Reprodutibilidade dos Testes , Sais/farmacologia , Dióxido de Silício/química , Software , Temperatura
15.
Proc Natl Acad Sci U S A ; 105(23): 7941-6, 2008 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-18359849

RESUMO

The mechanics of microtubules, cylindrical protein filaments that constitute the cytoskeleton, have been well characterized on long length scales. Here, we investigate the persistence length of short (approximately 0.1 microm) ends of microtubules by measuring the trajectories of kinesin-propelled microtubules under perpendicular electric forces. We relate the measured trajectory curvatures to the biased thermal fluctuations of the leading microtubule end, and upon including all electrohydrodynamic forces, we find that the persistence length of the microtubule ends is only 0.08 +/- 0.02 mm. This is significantly shorter than the well established value of approximately 4-8 mm that is measured for long microtubules. Our data are in good agreement with recent theoretical predictions that microtubules mechanically behave as a loose assembly of independent protofilaments on these short length scales.


Assuntos
Microtúbulos/química , Animais , Fenômenos Biomecânicos , Bovinos , Drosophila melanogaster , Eletricidade
16.
Front Med (Lausanne) ; 8: 642380, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33937286

RESUMO

Despite significant progress in the development of treatment options, melanoma remains a leading cause of death due to skin cancer. Advances in our understanding of the genetic, transcriptomic, and morphologic spectrum of benign and malignant melanocytic neoplasia have enabled the field to propose biomarkers with potential diagnostic, prognostic, and predictive value. While these proposed biomarkers have the potential to improve clinical decision making at multiple critical intervention points, most remain unvalidated. Clinical validation of even the most commonly assessed biomarkers will require substantial resources, including limited clinical specimens. It is therefore important to consider the properties that constitute a relevant and clinically-useful biomarker-based test prior to engaging in large validation studies. In this review article we adapt an established framework for determining minimally-useful biomarker test characteristics, and apply this framework to a discussion of currently used and proposed biomarkers designed to aid melanoma detection, staging, prognosis, and choice of treatment.

17.
J Pediatr Surg ; 56(2): 239-244, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32829881

RESUMO

PURPOSE: Assessing quality of life (QoL) after esophageal replacement (ER) for long gap esophageal atresia (LGEA). METHODS: All patients after ER for LGEA with gastric pull-up (GPU n = 9) or jejunum interposition (JI n = 14) at the University Medical Center Groningen and Utrecht (1985-2007) were included. QoL was assessed with 1) gastrointestinal-related QoL using the Gastrointestinal Quality of Life Index (GIQLI)), 2) general QoL (Child Health questionnaire CHF87-BREF (children)/World Health Organization questionnaire WHOQOL-BREF (adults)), and 3) health-related QoL (HRQoL) (TNO AZL TACQoL/TAAQoL). Association of morbidity (heartburn, dysphagia, dyspnea on exertion, recurrent cough) and (HR)QoL was evaluated. RESULTS: Six patients after GPU (75%) and eight patients after JI (57%) responded to the questionnaires (mean age 15.7, SD 5.9, 12 male, two female). Mean gastrointestinal, general and health-related QoL total scores of the patients were comparable to healthy controls. However, young adults reported a worse physical functioning (p = 0.02) but better social functioning compared to peers (p = 0.01). Morbidity was not associated with significant differences in (HR)QoL. CONCLUSIONS: With the current validated QoL most patients after ER with GPU and JI for LGEA have normal generic and disease specific QoL scores. Postoperative morbidity does not seem to influence (HR)QoL. TYPE OF STUDY: Prognosis Study. LEVEL OF EVIDENCE: III.


Assuntos
Atresia Esofágica , Esofagoplastia , Adolescente , Anastomose Cirúrgica , Criança , Atresia Esofágica/cirurgia , Feminino , Humanos , Masculino , Qualidade de Vida , Inquéritos e Questionários , Adulto Jovem
18.
Nature ; 432(7015): 371-4, 2004 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-15549099

RESUMO

The interplay between discrete vibrational and electronic degrees of freedom directly influences the chemical and physical properties of molecular systems. This coupling is typically studied through optical methods such as fluorescence, absorption and Raman spectroscopy. Molecular electronic devices provide new opportunities for exploring vibration-electronic interactions at the single molecule level. For example, electrons injected from a scanning tunnelling microscope tip into a metal can excite vibrational excitations of a molecule situated in the gap between tip and metal. Here we show how current directly injected into a freely suspended individual single-wall carbon nanotube can be used to excite, detect and control a specific vibrational mode of the molecule. Electrons tunnelling inelastically into the nanotube cause a non-equilibrium occupation of the radial breathing mode, leading to both stimulated emission and absorption of phonons by successive electron tunnelling events. We exploit this effect to measure a phonon lifetime of the order of 10 ns, corresponding to a quality factor of well over 10,000 for this nanomechanical oscillator.

19.
Nucleic Acids Res ; 36(16): e104, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18658247

RESUMO

Many experiments involving nucleic acids require the hybridization and ligation of multiple DNA or RNA molecules to form a compound molecule. When one of the constituents is single stranded, however, the efficiency of ligation can be very low and requires significant individually tailored optimization. Also, when the molecules involved are very long (>10 kb), the reaction efficiency typically reduces dramatically. Here, we present a simple procedure to efficiently and specifically end-join two different nucleic acids using the well-known biotin-streptavidin linkage. We introduce a two-step approach, in which we initially bind only one molecule to streptavidin (STV). The second molecule is added only after complete removal of the unbound STV. This primarily forms heterodimers and nearly completely suppresses formation of unwanted homodimers. We demonstrate that the joining efficiency is 50 +/- 25% and is insensitive to molecule length (up to at least 20 kb). Furthermore, our method eliminates the requirement for specific complementary overhangs and can therefore be applied to both DNA and RNA. Demonstrated examples of the method include the efficient end-joining of DNA to single-stranded and double-stranded RNA, and the joining of two double-stranded RNA molecules. End-joining of long nucleic acids using this procedure may find applications in bionanotechnology and in single-molecule experiments.


Assuntos
DNA/química , RNA/química , Bioquímica/métodos , Biotinilação , Dimerização , Microscopia de Força Atômica , Estreptavidina/química
20.
PLoS Genet ; 3(8): e139, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17784788

RESUMO

Crossing over during meiotic prophase I is required for sexual reproduction in mice and contributes to genome-wide genetic diversity. Here we report on the characterization of an N-ethyl-N-nitrosourea-induced, recessive allele called mei4, which causes sterility in both sexes owing to meiotic defects. In mutant spermatocytes, chromosomes fail to congress properly at the metaphase plate, leading to arrest and apoptosis before the first meiotic division. Mutant oocytes have a similar chromosomal phenotype but in vitro can undergo meiotic divisions and fertilization before arresting. During late meiotic prophase in mei4 mutant males, absence of cyclin dependent kinase 2 and mismatch repair protein association from chromosome cores is correlated with the premature separation of bivalents at diplonema owing to lack of chiasmata. We have identified the causative mutation, a transversion in the 5' splice donor site of exon 1 in the mouse ortholog of Human Enhancer of Invasion 10 (Hei10; also known as Gm288 in mouse and CCNB1IP1 in human), a putative B-type cyclin E3 ubiquitin ligase. Importantly, orthologs of Hei10 are found exclusively in deuterostomes and not in more ancestral protostomes such as yeast, worms, or flies. The cloning and characterization of the mei4 allele of Hei10 demonstrates a novel link between cell cycle regulation and mismatch repair during prophase I.


Assuntos
Proteínas de Ciclo Celular/genética , Troca Genética/genética , Prófase Meiótica I/genética , Mutação , Ubiquitina-Proteína Ligases/genética , Proteínas Adaptadoras de Transdução de Sinal , Alelos , Animais , Pareamento Incorreto de Bases/genética , Bovinos , Proteínas de Ciclo Celular/fisiologia , Quinase 2 Dependente de Ciclina/deficiência , Quinase 2 Dependente de Ciclina/genética , Quinase 2 Dependente de Ciclina/metabolismo , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Camundongos Knockout , Recombinação Genética , Ubiquitina-Proteína Ligases/fisiologia
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