Flatness optimization of micro-injection moulded parts: The case of a PMMA microfluidic component

Micro-injection moulding (µ-IM) has attracted a lot of interest because of its potential for the production of low-cost, miniaturized parts in high-volume. Applications of this technology are, amongst others, microfluidic components for lab-on-a-chip devices and micro-optical components. In both cases, the control of the part flatness is a key aspect to maintaining the component's functionality. The objective of this work is to determine the factors affecting the flatness of a polymer part manufactured by µ-IM and to control the manufacturing process with the aim of minimizing the in-process part deformation. As a case study, a PMMA microfluidic substrate with overall dimensions of 10 mm diameter and 1 mm thickness was investigated by designing a µ-IM experiment having flatness as the experimental response. The part flatness was measured using a micro-coordinate measuring machine. Finite elements analysis was also carried out to study the optimal ejection pin configuration. The results of this work show that the control of the µ-IM process conditions can improve the flatness of the polymer part up to about 15 µm. Part flatness as low as 4 µm can be achieved by modifying the design of the ejection system according to suggested guideline

Design and fabrication of a three-dimensional microfluidic device for blood separation using micro-injection moulding

Micro-manufacturing is a fast developing area due to the increasing demand for components and systems of high precision and small dimensions. A number of challenges are yet to be overcome before the full potential of such techniques is realised. Examples of such challenges include limitations in component geometry, material selection and suitability for mass production. Some micro-manufacturing techniques are still at early development stages, while other techniques are at higher stage of manufacturing readiness level but require adaptation in part design or manufacturing procedure to overcome such limitations. This article presents a case study, where the design of a micro-scale, biomedical device is adapted for functionality and manufacturability by a high-volume micro-fabrication technique. Investigations are described towards a disposable three-dimensional, polymer-based device for the separation of blood cells and plasma. The importance of attempting a three-dimensional device design and fabrication route was to take advantage of the highthroughput per unit volume that such systems can, in principle, allow. The importance of a micro-moulding fabrication route was to allow such blood-containing devices to be cheaply manufactured for disposability. Initial device tests showed separation efficiency up to approximately 80% with diluted blood samples. The produced prototype indicated that the process flow was suitable for high-volume fabrication of three-dimensional microfluidics

Cystic fibrosis transmembrane conductance regulator gene mutations and glutathione S-transferase null genotypes in cystic fibrosis patients in Brazil

OBJECTIVE: To determine the effects that mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene and deletion of the glutathione S-transferase (GST) genes mu-1 (GSTM1) and theta-1 (GSTT1) have on the clinical course of cystic fibrosis (CF) in patients residing in the southeastern region of Brazil. METHODS: The study sample consisted of all consecutive CF patients treated at the Hospital de Clínicas School of Medical Sciences of the State University at Campinas between March of 2002 and March of 2005. We included 66 CF patients. Genomic DNA was analyzed by polymerase chain reaction and restriction endonuclease digestion for the identification of the genotypes. RESULTS: The DF508 mutation of the CFTR gene was found in 44 patients (66.7%). The null genotypes GSTM1, GSTT1 and GSTM1/GSTT1 were found in 40.9%, 15.2%, and 3.0% of the patients, respectively. The DF508 CFTR mutation was more common in patients diagnosed with CF before 2.5 years of age than in those diagnosed later (75.5% vs. 41.2%; p = 0.008). The frequency of the DF508 CFTR mutation, as well as of the GSTM1 and GSTT1 genotypes, was not found to be associated with gender, ethnicity, pulmonary disease status, or pancreatic disease status. CONCLUSIONS: When the patients were stratified by clinical and epidemiological features, the frequencies of the GSTM1 and GSTT1 null genotypes were similar, suggesting that the inherited absence of these enzymatic pathways does not alter the course of CF. However, the high frequency of the DF508 CFTR mutation found in younger children suggests that it influences the age at diagnosis of CF in this region of Brazil.OBJETIVO: Determinar os efeitos que a mutação do gene cystic fibrosis transmembrane conductance regulator (CFTR) e da deleção dos genes glutationa S-transferase (GST) mu-1 (GSTM1) e teta-1 (GSTT1) têm na evolução clínica da fibrose cística (FC) em pacientes da região sudeste do Brasil. MÉTODOS: Entre março de 2002 e março de 2005, incluímos no estudo todos os pacientes com FC atendidos consecutivamente no Departamento de Pediatria do Hospital de Clínicas da Faculdade de Ciências Médicas da Universidade Estadual de Campinas. O DNA genômico de 66 pacientes com FC foi analisado por PCR e digestão com endonuclease de restrição para a identificação dos genótipos. RESULTADOS: A mutação ΔF508 do gene CFTR foi identificada em 44 (66,7%) pacientes. As deleções dos genes GSTM1, GSTT1 e da combinação nula GSTM1/GSTT1 foram identificadas em 40,9%, 15,2% e 3,0% dos pacientes, respectivamente. A mutação ΔF508 do gene CFTR foi mais comum em pacientes diagnosticados com FC antes dos 2,5 anos de idade que naqueles diagnosticados mais tarde (75,5% vs. 41,2%; p = 0,008). CONCLUSÕES: Foram observadas frequências similares da mutação ΔF508 do gene CFTR e dos genótipos GSTM1 e GSTT1 nos pacientes, independentemente do sexo, etnia ou status da doença pulmonar ou pancreática. Quando os pacientes foram estratificados por aspectos clínicos e epidemiológicos, as frequências dos genótipos GSTM1 e GSTT1 nulos foram semelhantes, sugerindo que a ausência herdada dessas vias enzimáticas não altera o curso da FC. Em contraste, a alta frequência da mutação ΔF508 no gene CFTR encontrada em pacientes mais jovens sugere que essa mutação influencia a idade no momento do diagnóstico de FC nessa região do país.505

Polymorphisms in the glutathione pathway modulate cystic fibrosis severity: a cross-sectional study

BACKGROUND: Cystic fibrosis (CF) clinically manifests with various levels of severity, which are thought to be modulated by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR), modifier genes, and the environment. This study verified whether polymorphisms in modifier genes associated with glutathione (GSH) metabolism influence CF severity. METHODS: A cross-sectional study of 180 CF patients was carried out from 2011 to 2012. We analyzed CFTR mutations, polymorphisms (GSTM1 and GSTT1 deletions, GSTP1 + 313A > G, GCLC-129C > T, and GCLC-3506A > G) in modifier genes and CF clinical severity as assessed by 28 clinical and laboratory variables. RESULTS: Significant associations were found between modifier gene polymorphisms and particular phenotypes or genotype changes. These included GCLC-129C > T with a higher frequency of the Pseudomonas aeruginosa mucoid to CC genotype (p = 0.044), and GCLC-3506A > G with a higher frequency of the no-mucoid P. aeruginosa (NMPA) to AA genotype (p = 0.012). The GSTT1 deletion was associated with a higher frequency of the NMPA to homozygous deletion (p = 0.008), GSTP1 + 313A > G with a minor risk of osteoporosis (p = 0.036), and patient age ≤ 154 months (p = 0.044) with the AA genotype. The Bhalla score was associated with GCLC-3506A > G (p = 0.044) and GSTM1/GSTT1 deletion polymorphisms (p = 0.02), while transcutaneous hemoglobin oxygen saturation levels were associated with GSTT1 deletions (p = 0.048). CONCLUSION: CF severity is associated with polymorphisms in GSH pathways and CFTR mutations

Patchy and Janus Nanoparticles by Self-Organization of Mixtures of Fluorinated and Hydrogenated Alkanethiolates on the Surface of a Gold Core

The spontaneous self-organization of dissimilar ligands on the surface of metal nanoparticles is a very appealing approach to obtain anisotropic "spherical". systems. In addition to differences in ligand length and end groups, a further thermodynamic driving force to control the self-assembled monolayer organization may become available if the ligands are inherently immiscible, as is the case of hydrogenated (H-) and fluorinated (F-) species. Here, we validate the viability of this approach by combining F-19 NMR experiments and multiscale molecular simulations on large sets of mixed-monolayer-protected gold nanoparticles (NPs). The phase segregation of blends of F- and H-thiolates grafted on the surface of gold NPs allows a straightforward approach to patterned mixed monolayers, with the shapes of the monolayer domains being encoded in the structure of the F/H-thiolate ligands. The results obtained from this comprehensive study offer molecular design rules to achieve a precise control of inorganic nanoparticles protected by specifically patterned monolayers

Gold nanoparticles with\ua0patterned surface monolayers for\ua0nanomedicine: current perspectives

Molecular self-assembly is a topic attracting intense scientific interest. Various strategies have been developed for construction of molecular aggregates with rationally designed properties, geometries, and dimensions that promise to provide solutions to both theoretical and practical problems in areassuch as drug delivery, medical diagnostics, and biosensors, to name but a few. In this respect, gold nanoparticles covered with self-assembled monolayers presenting nanoscale surface patterns\u2014typically patched, striped or Janus-like domains\u2014represent an emerging field. These systems are particularly intriguing for use in bio-nanotechnology applications, as presence of such monolayers with three-dimensional (3D) morphology providesnanoparticles with surface-dependent properties that, in turn, affect their biological behavior. Comprehensive understanding of the physicochemical interactions occurring at the interface between these versatile nanomaterials and biological systems is therefore crucial to fully exploit their potential. This review aims to explore the current state of development of such patterned, self-assembled monolayer-protected gold nanoparticles, through step-by-step analysis of their conceptual design, synthetic procedures, predicted and determined surface characteristics, interactions with and performance in biological environments, and experimental and computational methods currently employed for their investigation

EFEITO DA RESTRIÇÃO ALIMENTAR QUANTITATIVA SOBRE O DESEMPENHO E AS CARACTERÍSTICAS DA CARCAÇA DE SUÍNOS EM TERMINAÇÃO

Neste experimento foi investigado o efeito da restrição alimentar quantitativa sobre o desempenho e a qualidade da carcaça de suínos em terminação. A restrição alimentar, na razão de 7 % (T2), 14 % (T3) e 21 % (T4) do consumo à vontade (T1), diminuiu linearmente o ganho de peso diário e a espessura de toucinho, e aumentou linearmente a idade de abate (P < 0,05), enquanto o peso e o rendimento de carcaça foram afetados de forma quadrática e a percentagem de pernil na carcaça aumentou linearmente conforme se diminuía a quantidade de ração fornecida (P < 0,05). Abstract The effect of quantitative feed restriction upon the performance and carcass characteristics of the finished pigs was investigated. It was observed a linear reduction in the daily weight gain and backfat and linear increasing in the slaughtery age (

Measurements of CFTR-Mediated Cl- Secretion in Human Rectal Biopsies Constitute a Robust Biomarker for Cystic Fibrosis Diagnosis and Prognosis

BACKGROUND: Cystic Fibrosis (CF) is caused by ∼1,900 mutations in the CF transmembrane conductance regulator (CFTR) gene encoding for a cAMP-regulated chloride (Cl(-)) channel expressed in several epithelia. Clinical features are dominated by respiratory symptoms, but there is variable organ involvement thus causing diagnostic dilemmas, especially for non-classic cases. METHODOLOGY/PRINCIPAL FINDINGS: To further establish measurement of CFTR function as a sensitive and robust biomarker for diagnosis and prognosis of CF, we herein assessed cholinergic and cAMP-CFTR-mediated Cl(-) secretion in 524 freshly excised rectal biopsies from 118 individuals, including patients with confirmed CF clinical diagnosis (n=51), individuals with clinical CF suspicion (n=49) and age-matched non-CF controls (n=18). Conclusive measurements were obtained for 96% of cases. Patients with "Classic CF", presenting earlier onset of symptoms, pancreatic insufficiency, severe lung disease and low Shwachman-Kulczycki scores were found to lack CFTR-mediated Cl(-) secretion (<5%). Individuals with milder CF disease presented residual CFTR-mediated Cl(-) secretion (10-57%) and non-CF controls show CFTR-mediated Cl(-) secretion ≥ 30-35% and data evidenced good correlations with various clinical parameters. Finally, comparison of these values with those in "CF suspicion" individuals allowed to confirm CF in 16/49 individuals (33%) and exclude it in 28/49 (57%). Statistical discriminant analyses showed that colonic measurements of CFTR-mediated Cl(-) secretion are the best discriminator among Classic/Non-Classic CF and non-CF groups. CONCLUSIONS/SIGNIFICANCE: Determination of CFTR-mediated Cl(-) secretion in rectal biopsies is demonstrated here to be a sensitive, reproducible and robust predictive biomarker for the diagnosis and prognosis of CF. The method also has very high potential for (pre-)clinical trials of CFTR-modulator therapies.This work was supported by grants TargetScreen2 (EU/FP6/LSH/2005/037365), PIC/IC/83103/2007; PTDC/MAT/118335/2010; PEstOE/BIA/UI4046/2011 (to BioFIG) and PEstOE/MAT/UI0006/2011 (to CEAUL) from FCT (Portugal); and FAPESP (SPRF, Brazil), CNPq (40.8924/2006/3, Brazil) and Mukoviszidose e.V. S02/10 (Germany). MS and IU are recipients of SFRH/BD/35936/2007 and SFRH/BD/69180/2010 PhD fellowships (FCT, Portugal), respectively. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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Presentación realizada en: 13º Mediterranean Climate Outlook Forum (MedCOF) celebrado de forma online entre el 15 de octubre y el 26 de noviembre de 2019

A direct physical interaction between Nanog and Sox2 regulates embryonic stem cell self-renewal

Embryonic stem (ES) cell self-renewal efficiency is determined by the Nanog protein level. However, the protein partners of Nanog that function to direct self-renewal are unclear. Here, we identify a Nanog interactome of over 130 proteins including transcription factors, chromatin modifying complexes, phosphorylation and ubiquitination enzymes, basal transcriptional machinery members, and RNA processing factors. Sox2 was identified as a robust interacting partner of Nanog. The purified Nanog–Sox2 complex identified a DNA recognition sequence present in multiple overlapping Nanog/Sox2 ChIP-Seq data sets. The Nanog tryptophan repeat region is necessary and sufficient for interaction with Sox2, with tryptophan residues required. In Sox2, tyrosine to alanine mutations within a triple-repeat motif (S X T/S Y) abrogates the Nanog–Sox2 interaction, alters expression of genes associated with the Nanog-Sox2 cognate sequence, and reduces the ability of Sox2 to rescue ES cell differentiation induced by endogenous Sox2 deletion. Substitution of the tyrosines with phenylalanine rescues both the Sox2–Nanog interaction and efficient self-renewal. These results suggest that aromatic stacking of Nanog tryptophans and Sox2 tyrosines mediates an interaction central to ES cell self-renewal