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1.
Nanoscale ; 13(31): 13353-13367, 2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34477741

RESUMO

Despite the significance of surface absorbed proteins in determining the biological identity of nanoparticles (NPs) entering the human body, little is known about the surface corona and factors that shape their formation on dietary particles used as food additives. In this study, food grade NPs of silica and titania and their food additive counterparts (E551 and E171) were interacted with milk proteins or with skimmed milk and the levels of protein adsorption were quantified. Characteristics of proteins correlating with their level of adsorption to NPs were determined using partial least squares regression analysis. Results from individual protein-particle interactions revealed the significance of factors such as zeta potential, hydrophobicity and hydrodynamic size of particles, and protein characteristics such as the number of beta strands, isoelectric points, the number of amino acid units (Ile, Tyr, Ala, Gly, Pro, Asp, and Arg), and phosphorylation sites on their adsorption to particles. Similar regression analysis was performed to identify the characteristics of twenty abundant and enriched proteins (identified using LC-MS/MS analysis) for their association with the surface corona of milk-interacted particles. Contrary to individual protein-particle interactions, protein characteristics such as helices, turns, protein structures, disulfide bonds, the number of amino acid units (Cys, Met, Leu, and Trp), and Fe binding sites were significant for their association with the surface corona of milk interacted particles. This difference in factors identified from individual proteins and milk interacted particles suggested possible interactions of proteins with surface adsorbed biomolecules as revealed by scanning transmission X-ray microscopy and other biochemical assays.


Assuntos
Nanopartículas , Coroa de Proteína , Adsorção , Sequência de Aminoácidos , Cromatografia Líquida , Humanos , Proteoma , Espectrometria de Massas em Tandem
2.
J Microbiol Methods ; 187: 106275, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34182074

RESUMO

Four methods were tested for enumerating bacteria present in the absorbent pads (AP) used in packaging chicken and other meats. Viable counts were ascertained at day 0 and day 7 (d0 and d7, respectively). Sampling bacterial cells from AP were carried out using a countertop blender, Stomacher, sonication, and blender in combination to sonication. The release of bacterial cells by breaking down the AP with the blender resulted in the highest CFU counts. At d0, a bacterial recovery rate of 94% was obtained with the blender, while the recovery rates using Stomacher or sonication alone were 58% and 73%, respectively. At d7, the Stomacher treatment also gave the lowest colony forming unit (CFU) values in the AP incubated at 7 °C. Sonication of the AP prior to homogenization with the blender did not increase CFU counts. Results suggested that breaking down the AP with a blender gives higher CFU levels than the Stomacher, which is the most commonly used technique for this purpose.

3.
Food Chem ; 360: 129956, 2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33965713

RESUMO

Essential oils (EOs) have potential utility as clean-label food preservatives due to their antimicrobial and antioxidant properties. In this study, various EOs were screened for their antimicrobial activities against Listeria grayi in vitro. The susceptibility of L. monocytogenes to select EOs was compared with that of L. grayi. The effectiveness of the selected EOs in inhibiting the growth of L. grayi on vegetable products was also investigated. The results showed that cinnamon and oregano EOs and carvacrol were effective in the vapor phase in inhibiting the growth of L. grayi as well as L. monocytogenes, with the susceptibility of L. monocytogenes to cinnamon EO being slightly higher than that of L. grayi. The packaging of green peppers with cellulose stickers impregnated with cinnamon EO at 556 µL/Lheadspace reduced the Listeria count to 1 log CFU/g after 2 days of storage as compared to 7.5 log CFU/g for controls.


Assuntos
Antibacterianos/farmacologia , Listeria monocytogenes/efeitos dos fármacos , Listeria/efeitos dos fármacos , Óleos Voláteis/farmacologia , Produtos Vegetais/microbiologia , Microbiologia de Alimentos , Conservantes de Alimentos , Testes de Sensibilidade Microbiana
4.
Foods ; 10(2)2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33670588

RESUMO

Animal welfare status is assessed today through visual evaluations requiring an on-farm visit. A convenient alternative would be to detect cow welfare status directly in milk samples, already routinely collected for milk recording. The objective of this study was to propose a novel approach to demonstrate that Fourier transform infrared (FTIR) spectroscopy can detect changes in milk composition related to cows subjected to movement restriction at the tie stall with four tie-rail configurations varying in height and position (TR1, TR2, TR3 and TR4). Milk mid-infrared spectra were collected on weekly basis. Long-term average spectra were calculated for each cow using spectra collected in weeks 8-10 of treatment. Principal component analysis was applied to spectral averages and the scores of principal components (PCs) were tested for treatment effect by mixed modelling. PC7 revealed a significant treatment effect (p = 0.01), particularly for TR3 (configuration with restricted movement) vs. TR1 (recommended configuration) (p = 0.03). The loading spectrum of PC7 revealed high loadings at wavenumbers that could be assigned to biomarkers related to negative energy balance, such as ß-hydroxybutyrate, citrate and acetone. This observation suggests that TR3 might have been restrictive for cows to access feed. Milk FTIR spectroscopy showed promising results in detecting welfare status and housing conditions in dairy cows.

5.
Analyst ; 145(10): 3678-3685, 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32307493

RESUMO

One of the great challenges in identifying effective therapy in many neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), is the lack of reliable biomarkers. In this study, we applied infrared imaging microspectroscopy, a valuable technique to investigate biomolecule fingerprints and secondary structure of proteins within biological tissue. We hypothesized that, since skin and CNS have the same embryonic origin, spectral differences associated with ALS-specific pathological events will be readily detectable through skin testing using this technique. Cells from healthy individuals and ALS patients were isolated from skin biopsies in order to generate tissue-engineered in vitro skin (TES). Infrared spectra of the generated TES were recorded using a focal-plane-array Fourier transform infrared (FPA-FTIR) spectrometer, and hierarchical cluster analysis of the spectral data was performed in order to establish clear differences between the tested TES specimens. Interestingly, our analyses showed that it was readily possible to discriminate ALS- and control-TES solely based on differences in associated FTIR spectra, mainly located between 1149 and 1473 cm-1, attributed to disruption of phospholipid cell membranes, extracellular matrix remodeling or cholesterol accumulation. Spectral differences within the TES samples may therefore be associated with disease state, paving the way for the identification of biomarkers in ALS.


Assuntos
Esclerose Amiotrófica Lateral/diagnóstico , Esclerose Amiotrófica Lateral/metabolismo , Pele/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Estudos de Casos e Controles , Humanos
6.
Polymers (Basel) ; 12(4)2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32326030

RESUMO

More than 10 million tons of textile waste are disposed through landfill every year in North America. The disposal of textile waste via landfill or incineration causes environmental problems and represents a waste of useful resources. In this work, we explored the possibility to directly extract cellulose nanocrystals (CNCs) from untreated textile waste through two methods, namely sulfuric acid hydrolysis and three-step oxidization. CNCs with cellulose Iß crystalline structure and rod-like shape were successfully obtained. The aspect ratios of CNCs prepared from acid hydrolysis and oxidization were 10.00 ± 3.39 and 17.10 ± 12.85, respectively. Their application as reinforcing agent of soybean protein isolate (SPI) film was evaluated. With the addition of 20% CNCs, the composite film maintained the high transparency, while their water vapor barrier property, tensile strength, and Young's modulus were significantly improved. This research demonstrates a promising approach to recycle textile waste, and more value-added applications based on the derived CNCs could be expected.

7.
J Agric Food Chem ; 67(44): 12264-12272, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31613615

RESUMO

While silica particles are used extensively in food products, different grades and temperature variants of silica particles have not been compared for their physiochemical and biological properties. Different grades of silica (food-grade nanoparticles (FG-NPs), nonfood-grade nanoparticles (NFG-NPs), and food-grade micron particles (FG-MPs)) and the temperature variants generated by exposing FG-NPs to wet heating, dry heating, and refrigeration were compared for their physicochemical properties and interaction with trypsin. FG-NPs were similar to NFG-NPs and FG-MPs in their elemental composition and amorphous nature but had relatively less branched and ring siloxane groups than the latter ones. There were subtle but noticeable changes in the agglomeration behavior and relative abundance of different silica groups in FG-NPs exposed to food-handling temperatures. Secondary structure and function of trypsin were negatively impacted by FG-NPs and their temperature variants. Silica particles showed a "mixed-type inhibition" of trypsin resulting in partial digestion of bovine serum albumin. In conclusion, our studies showed differences in the surface chemistry of different grades of silica particles and temperature variants of FG-NPs and their negative impact on the structure and function of trypsin.


Assuntos
Aditivos Alimentares/química , Nanopartículas/química , Dióxido de Silício/química , Tripsina/química , Animais , Biocatálise , Bovinos , Hidrodinâmica , Tamanho da Partícula , Soroalbumina Bovina/química , Propriedades de Superfície , Temperatura
8.
J Drug Assess ; 8(1): 115-121, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31231590

RESUMO

Background: The incidence of Type 2 Diabetes Mellitus (T2DM) in Egypt is considered one of the highest in the world. Metformin and Sulfonylureas are usually prescribed together due to their efficacy and their relatively low cost. Organic cation transport 1, encoded by SLC22A1 gene, is the main transporter of metformin into hepatocytes, which is considered metformin site of action. Sulfonylureas enhance insulin release from pancreatic B-cells through binding to sulfonylurea receptor 1, encoded by ABCC8 gene. Single nucleotide polymorphisms in the SLC22A1 and ABCC8 genes might affect the response of each drug. Aims: To investigate the influence of SLC22A1 rs622342 (A>C) and ABCC8 rs757110 (A>C) genetic variants on the efficacy of metformin and glimepiride combination therapy in Egyptian T2DM patients. Methods: Observational cross-sectional study in which patients receiving metformin and glimepiride combination therapy for at least 6 months were included for genotyping and classified into either responders or non-responders, based on their HbA1C level. Results: A total of 127 patients were included and genotyped. They were divided into 93 responders (HbA1C<7%) and 34 non-responders (HbA1C≥7%). Minor allele frequencies for rs622342 and rs757110 were 0.189 and 0.271, respectively. Only SLC22A1 rs622342 variant was found to be associated with the response of combination therapy, in which AA alleles carriers were 2.7-times more responsive to metformin than C allele carriers (Recessive model, odds ratio = 2.718, p = 0.025, 95% CI = 1.112-6.385). Conclusion: Genotyping of rs622342 can be useful in predicting the response to metformin in combination therapy in Egyptian T2DM patients.

9.
J Clin Microbiol ; 57(5)2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30787141

RESUMO

Invasive fungal infections by opportunistic yeasts have increased concomitantly with the growth of an immunocompromised patient population. Misidentification of yeasts can lead to inappropriate antifungal treatment and complications. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy is a promising method for rapid and accurate identification of microorganisms. ATR-FTIR spectroscopy is a standalone, inexpensive, reagent-free technique that provides results within minutes after initial culture. In this study, a comprehensive spectral reference database of 65 clinically relevant yeast species was constructed and tested prospectively on spectra recorded (from colonies taken from culture plates) for 318 routine yeasts isolated from various body fluids and specimens received from 38 microbiology laboratories over a 4-month period in our clinical laboratory. ATR-FTIR spectroscopy attained comparable identification performance with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). In a preliminary validation of the ATR-FTIR method, correct identification rates of 100% and 95.6% at the genus and species levels, respectively, were achieved, with 3.5% unidentified and 0.9% misidentified. By expanding the number of spectra in the spectral reference database for species for which isolates could not be identified or had been misidentified, we were able to improve identification at the species level to 99.7%. Thus, ATR-FTIR spectroscopy provides a new standalone method that can rival MALDI-TOF MS for the accurate identification of a broad range of medically important yeasts. The simplicity of the ATR-FTIR spectroscopy workflow favors its use in clinical laboratories for timely and low-cost identification of life-threatening yeast strains for appropriate treatment.


Assuntos
Líquidos Corporais/microbiologia , Micoses/microbiologia , Leveduras/isolamento & purificação , Bases de Dados Factuais , Humanos , Indicadores e Reagentes , Micoses/diagnóstico , Estudos Prospectivos , Espectroscopia de Infravermelho com Transformada de Fourier , Leveduras/classificação
10.
Biotechnol J ; 14(1): e1800306, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30488607

RESUMO

There is a strong clinical need to develop small-caliber tissue-engineered blood vessels for arterial bypass surgeries. Such substitutes can be engineered using the self-assembly approach in which cells produce their own extracellular matrix (ECM), creating a robust vessel without exogenous material. However, this approach is currently limited to the production of flat sheets that need to be further rolled into the final desired tubular shape. In this study, human fibroblasts and smooth muscle cells were seeded directly on UV-C-treated cylindrical polyethylene terephthalate glycol-modified (PETG) mandrels of 4.8 mm diameter. UV-C treatment induced surface modification, confirmed by Fourier-transform infrared spectroscopy (FTIR) analysis, was necessary to ensure proper cellular attachment and optimized ECM secretion/assembly. This novel approach generated solid tubular conduits with high level of cohesion between concentric cellular layers and enhanced cell-driven circumferential alignment that can be manipulated after 21 days of culture. This simple and cost-effective mandrel-seeded approach also allowed for endothelialization of the construct and the production of perfusable trilayered tissue-engineered blood vessels with a closed lumen. This study lays the foundation for a broad field of possible applications enabling custom-made reconstructed tissues of specialized shapes using a surface treated 3D structure as a template for tissue engineering.


Assuntos
Engenharia Tecidual/métodos , Animais , Prótese Vascular , Fibroblastos/citologia , Fibroblastos/metabolismo , Humanos , Espectroscopia de Infravermelho com Transformada de Fourier , Tecidos Suporte
11.
Sensors (Basel) ; 15(3): 4734-48, 2015 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-25730479

RESUMO

The eco-toxicological indicators used to evaluate soil quality complement the physico-chemical criteria employed in contaminated site remediation, but their cost, time, sophisticated analytical methods and in-situ inapplicability pose a major challenge to rapidly detect and map the extent of soil contamination. This paper describes a sensor-based approach for measuring potential (substrate-induced) microbial respiration in diesel-contaminated and non-contaminated soil and hence, indirectly evaluates their microbial activity. A simple CO2 sensing system was developed using an inexpensive non-dispersive infrared (NDIR) CO2 sensor and was successfully deployed to differentiate the control and diesel-contaminated soils in terms of CO2 emission after glucose addition. Also, the sensor system distinguished glucose-induced CO2 emission from sterile and control soil samples (p ≤ 0.0001). Significant effects of diesel contamination (p ≤ 0.0001) and soil type (p ≤ 0.0001) on glucose-induced CO2 emission were also found. The developed sensing system can provide in-situ evaluation of soil microbial activity, an indicator of soil quality. The system can be a promising tool for the initial screening of contaminated environmental sites to create high spatial density maps at a relatively low cost.


Assuntos
Biodegradação Ambiental , Técnicas Biossensoriais , Dióxido de Carbono/isolamento & purificação , Poluentes do Solo/isolamento & purificação , Dióxido de Carbono/toxicidade , Respiração Celular/efeitos dos fármacos , Gasolina/toxicidade , Humanos , Microbiologia do Solo , Poluentes do Solo/química , Espectrofotometria Infravermelho
12.
Harv Rev Psychiatry ; 21(3): 138-50, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23660969

RESUMO

OBJECTIVE: To review the literature on quality of life (QoL) in borderline personality disorder (BPD) by examining the use of QoL instruments, the extent of QoL impairments in BPD, and the impact of treatment on QoL in BPD. METHODS: Studies were identified through PubMed and PsycINFO searches for articles from 1980 to 2011 using the following keywords: quality of life OR health-related quality of life OR QOL OR HRQOL AND borderline personality disorder. We focused our search on studies that actually measured QoL. Two authors agreed independently on including 25 studies that met specific selection criteria. RESULTS: The data on QoL in BPD are still sparse, with high heterogeneity in the instruments used to measure QoL, which decreases the comparability of existing studies. EQ-5D, WHOQOL, SF-36, Satisfaction Profile, and Q-LESQ have been utilized as QoL measures in BPD research. The reviewed studies uniformly demonstrated grave impairments in QoL of BPD patients. The available evidence indicates that BPD treatments improve not only psychiatric symptoms but also QoL, as shown by psychotherapy and pharmacotherapy studies. Nevertheless, it remains unclear whether current treatments are able to restore QoL to community norms. CONCLUSIONS: QoL is gaining more importance as an outcome measure of psychiatric interventions. Research evidence confirms that QoL is seriously impaired in BPD and that QoL improves with treatment. Further research is needed to build a consensus on the utilization of QoL measures and to improve their validity in BPD. More importantly, future studies need to develop and test interventions to improve QoL in BPD.


Assuntos
Transtorno da Personalidade Borderline/psicologia , Qualidade de Vida/psicologia , Transtorno da Personalidade Borderline/tratamento farmacológico , Transtorno da Personalidade Borderline/terapia , Terapia Combinada , Feminino , Humanos , Masculino , Escalas de Graduação Psiquiátrica , Testes Psicológicos , Psicoterapia , Psicotrópicos/uso terapêutico , Resultado do Tratamento
13.
Turk Neurosurg ; 23(1): 61-6, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23344869

RESUMO

AIM: Evaluation of the laparoscopic assisted revision of the ventriculoperitoneal shunt as an alternative technique to the traditional laparotomy. MATERIAL AND METHODS: Out of 1181 elective neurosurgical procedures have been done from January 2009 to December 2010. There are 98 (8.2%) ventriculoperitoneal shunt procedures. New shunt insertion was performed 41 times (41.9%) and shunt revision performed 57 times (58.1%). Shunt-related infection was detected in 11 cases (11.22%) while mechanical failure was found in 46 cases (46.9%), proximal obstruction was diagnosed in 26 cases (26.5 %) while 20 patients (20.4%) suffered from distal obstruction. Out of the 20 patients with distal obstruction, 12 patients were treated with laparoscopic assisted revision of the peritoneal end. RESULTS: Intra operative finding revealed peritoneal adhesion in 83.3% of cases and cerebrospinal fluid pseudo cyst in 16.6% while extra peritoneal tube was found in one case. Intraoperative management included adhesiolysis in 10 patient, evacuation and marsupialization of the cyst in two cases in addition to tube repositioning in all cases. There was no procedure-related complications. CONCLUSION: Laparoscopic assisted revision of the peritoneal catheter is an alternative technique to traditional laparotomy in the revision of ventriculoperitoneal shunt.


Assuntos
Hidrocefalia/cirurgia , Laparoscopia/métodos , Reoperação/métodos , Derivação Ventriculoperitoneal/efeitos adversos , Derivação Ventriculoperitoneal/métodos , Adolescente , Adulto , Criança , Análise de Falha de Equipamento , Feminino , Humanos , Masculino , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/etiologia , Infecções Relacionadas à Prótese/diagnóstico , Infecções Relacionadas à Prótese/etiologia , Aderências Teciduais/diagnóstico , Aderências Teciduais/etiologia , Adulto Jovem
14.
Diagn Microbiol Infect Dis ; 70(2): 157-66, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21596219

RESUMO

The emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) carrying Panton-Valentine leukocidin is a worldwide problem. Their identification is based currently on costly and complicated molecular methods. This article describes a simple method for differentiating CA-MRSA from hospital-associated (HA) epidemic MRSA pulsed-field gel electrophoresis types using Fourier transform infrared (FTIR) spectroscopy. The 47 CA-MRSA isolates included 3 Southwest Pacific (resembling USA1100), 24 CMRSA7 (resembling USA400/MW2), 19 CMRSA10 (resembling USA300), and 1 European ST80, while HA-MRSA were represented by 27, 16, 11, 15, 7, and 8 Canadian epidemic isolates CMRSA1 through CMRSA6 respectively, plus 25 nontyped Canadian HA-MRSA. Principal component analysis (PCA), self-organized maps (SOMs), and the K-nearest neighbor (KNN) method were used to cluster the isolates based on chemometric analysis of FTIR spectra of dried films of stationary-phase cells grown on Que-Bact® Universal Medium No. 2 (Quelab Laboratories, Montreal, QC, Canada). First-derivative normalized data from a single narrow spectral region (1361-1236 cm(-1), suggesting differences in protein amide III and nucleic acid phosphodiester contents) allowed 98% correct classification by KNN, 93% by SOMs, and 92% by PCA. FTIR spectroscopic analysis of cells grown on Que-Bact® Universal Medium No. 2 offers a rapid and simple alternative to molecular methods for routine identification of CA-MRSA epidemic isolates.


Assuntos
Técnicas Bacteriológicas/métodos , Infecções Comunitárias Adquiridas/microbiologia , Staphylococcus aureus Resistente à Meticilina/química , Staphylococcus aureus Resistente à Meticilina/classificação , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Infecções Estafilocócicas/microbiologia , Análise por Conglomerados , Infecções Comunitárias Adquiridas/diagnóstico , Humanos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Tipagem Molecular , Sensibilidade e Especificidade , Infecções Estafilocócicas/diagnóstico
15.
Environ Sci Technol ; 44(11): 4136-41, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-20438073

RESUMO

The effects of dissolved oxygen tension during bacterial growth and acclimation on the cell surface properties and biochemical composition of the bacterial pathogens Escherichia coli O157:H7 and Yersinia enterocolitica are characterized. Three experimental techniques are used in an effort to understand the influence of bacterial growth and acclimation conditions on cell surface charge and the composition of the bacterial cell: (i) electrophoretic mobility measurements; (ii) potentiometric titration; and (iii) ATR-FTIR spectroscopy. Potentiometric titration data analyzed using chemical speciation software are related to measured electrophoretic mobilities at the pH of interest. Titration of bacterial cells is used to identify the major proton-active functional groups and the overall concentration of these cell surface ligands at the cell membrane. Analysis of titration data shows notable differences between strains and conditions, confirming the appropriateness of this tool for an overall charge characterization. ATR-FTIR spectroscopy of whole cells is used to further characterize the bacterial biochemical composition and macromolecular structures that might be involved in the development of the net surficial charge of the organisms examined. The evaluation of the integrated intensities of HPO(2)(-) and carbohydrate absorption bands in the IR spectra reveals clear differences between growth protocols. Taken together, the three techniques seem to indicate that the dissolved oxygen tension during cell growth or acclimation can noticeably influence the expression of cell surface molecules and the measurable cell surface charge, though in a strain-dependent fashion.


Assuntos
Bactérias/metabolismo , Ensaio de Desvio de Mobilidade Eletroforética/métodos , Oxigênio/química , Potenciometria/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Microbiologia da Água
16.
J Antimicrob Chemother ; 61(1): 95-102, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17962217

RESUMO

OBJECTIVES: To evaluate Fourier transform infrared (FTIR) spectroscopy as a rapid method for distinguishing glycopeptide-intermediate Staphylococcus aureus (GISA) from glycopeptide-susceptible methicillin-resistant S. aureus (MRSA) and to compare three data analysis methods. METHODS: First-derivative normalized spectra of dried films of bacterial growth on Que-Bact Universal Medium No. 2 were examined by singular value decomposition to identify key spectral regions. Region selection was analysed by principal component analysis (PCA), self-organizing maps (SOMs) and the K-nearest neighbour (KNN) algorithm. The initial data set included 35 GISA (including GISA Mu50 and heterogeneous GISA Mu3) and 25 epidemic MRSA. The regions were then tested using enlarged data sets that included 22 sporadic and 85 additional epidemic MRSA. RESULTS: Epidemic MRSA and GISA/hGISA were separated into two distinct clusters on the basis of spectral data from regions 1352-1315 and 1480-1460 cm(-1), the former providing 100% correct classification by all three analyses and the latter providing 96.67% correct by PCA, 98.34% by SOM and 100% by KNN. The 1480-1460 cm(-1) region was more effective for distinguishing GISA/hGISA from a set combining sporadic and epidemic MRSA, with two GISA/hGISA and four sporadic MRSA misclassified by PCA and SOM (92.69% correct), while the KNN method misclassified three of the four sporadic MRSA (93.90% correct). The addition of 85 other epidemic MRSA this set increased the fraction of correctly classified isolates to 96.41% and 97.01% by PCA, SOM and KNN, respectively. CONCLUSIONS: As only 6 of 167 isolates were misclassified, FTIR spectroscopy may provide means of rapid and accurate identification of GISA and hGISA among isolates of MRSA.


Assuntos
Farmacorresistência Bacteriana/efeitos dos fármacos , Glicopeptídeos/farmacologia , Staphylococcus aureus/isolamento & purificação , Algoritmos , Antibacterianos/farmacologia , Humanos , Resistência a Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Análise de Componente Principal , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/classificação , Staphylococcus aureus/efeitos dos fármacos
17.
J Microbiol Methods ; 69(1): 146-53, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17316849

RESUMO

A rapid and simple typing system is needed for controlling the spread of epidemic methicillin-resistant Staphylococcus aureus (MRSA), currently one of the most widespread multi-resistant nosocomial pathogens in Canadian hospitals. Fourier transform infrared (FTIR) spectroscopy was used to subtype 85 isolates representing five strains of epidemic Canadian MRSA (CMRSA). Spectral fingerprints of whole cells grown on Que-Bact(R) Universal Medium No. 2 were transformed to first derivative peak-height normalized files and examined visually and by singular-value decomposition (SVD). Distinguishing spectral regions were processed by principal component analysis (PCA), self-organizing map and K-nearest neighbor supervised cluster analysis. Among the visually identified regions, 1070-1050 and 1155-1137 cm(-1) were found suitable for discrimination of CMRSA-4 and CMRSA-2 respectively, while CMRSA-1, CMRSA-3, and CMRSA-5 each exhibited distinctive spectral profiles in the 1123-1094 cm(-1) region. The combination, 1123-1094, 1174-1154 and 2904-2864 cm(-1) separated the five CMRSA with 84.6% correct classification by PCA. Five clusters were also obtained using the SVD-selected regions 1096-1066, 1118-1090 and 2914-2880 cm(-1), with 87.8% correct classification based on visual examination of the PCA scores plot and 97% based on supervised cluster analysis. These results demonstrate that FTIR spectroscopy has considerable potential as a rapid (1-hour) and simple method for MRSA strain typing and monitoring in clinical settings.


Assuntos
Técnicas de Tipagem Bacteriana/métodos , Resistência a Meticilina , Espectroscopia de Infravermelho com Transformada de Fourier , Infecções Estafilocócicas/diagnóstico , Staphylococcus aureus/classificação , Surtos de Doenças/prevenção & controle , Eletroforese em Gel de Campo Pulsado , Análise de Componente Principal , Reprodutibilidade dos Testes , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/isolamento & purificação
18.
J Microbiol Methods ; 68(2): 236-42, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17049398

RESUMO

Coagulase-negative staphylococci (CNS), frequently associated with both community-acquired and nosocomial bloodstream infections, must be distinguished from Staphylococcus aureus for clinical purposes. Conventional methods are too laborious and time-consuming and often lack sensitivity to CNS. Fourier transform infrared (FTIR) spectroscopy combined with the use of a universal growth medium (Que-Bact Universal Medium No. 2) and chemometrics was evaluated for its potential as a rapid and simple clinical tool for making this distinction. FTIR spectra of 11 methicillin-sensitive and 11 methicillin-resistant CNS isolates as well as 25 methicillin-sensitive, 47 methicillin-resistant, 34 borderline oxacillin-resistant and 35 glycopeptide intermediate S. aureus isolates were obtained from dried films of stationary-phase cells grown on the universal medium. Principal component analysis (PCA), self-organizing maps, and the K-nearest neighbor algorithm were employed to cluster the different phenotypes based on similarity of their FTIR spectra. PCA of the first-derivative normalized spectral data from a single narrow region (2888-2868 cm(-1)) yielded complete differentiation of CNS from both methicillin-sensitive and methicillin-resistant S. aureus. The rate of correct classification was somewhat reduced, from 100% to 90%, after inclusion of borderline oxacillin-resistant and glycopeptide intermediate S. aureus strains in the data set. Differentiation based on the data in broader spectral regions was much less reliable. The results of this study indicate that with proper spectral region selection, FTIR spectroscopy and cluster analysis may provide a simple and accurate means of CNS species identification.


Assuntos
Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/isolamento & purificação , Algoritmos , Coagulase , Humanos , Resistência a Meticilina , Análise de Componente Principal , Staphylococcus aureus/enzimologia
19.
J Food Prot ; 69(10): 2377-83, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17066916

RESUMO

A method was developed for whole-organism fingerprinting of Clostridium botulinum isolates by focal plane array Fourier transform infrared (FPA-FTIR) spectroscopy. A database of 150,000 infrared spectra of 44 strains of C. botulinum was acquired using a FPA-FTIR imaging spectrometer equipped with a 16 x 16 array detector to evaluate the ability of FTIR spectroscopy to differentiate the 44 strains. The database contained strains from C. botulinum groups I and II producing botulinum neurotoxin of serotypes A, B, E, and F. All strains were grown on each of three agar media (brain heart infusion, McClung Toabe agar base, and universal) prior to spectral acquisition. Given the dependence of the infrared spectra of microorganisms on the composition of the growth medium, the spectra were initially separated into three subsets corresponding to the three growth media employed. However, the replicate spectra of all strains, regardless of growth medium, were properly clustered by hierarchical cluster analysis based on differences in their infrared spectral profiles in three narrow spectral regions (1,428 to 1,412, 1,296 to 1,284, and 1,112 to 1,100 cm(-1)). The dendrogram generated from the FTIR data revealed complete separation between group I and group II strains. The spectral differences between group I and group II strains allowed accurate classification of C. botulinum strains at the group level in two blind validation studies (n = 40). These results demonstrate that FPA-FTIR spectroscopy has the potential for rapid discrimination of group I and group II C. botulinum strains in less than 3 min per sample.


Assuntos
Clostridium botulinum/classificação , Impressões Digitais de DNA/métodos , Microbiologia de Alimentos , Filogenia , Espectroscopia de Infravermelho com Transformada de Fourier , Sequência de Bases , Clostridium botulinum/genética , Clostridium botulinum/isolamento & purificação , Análise por Conglomerados , DNA Bacteriano/química , Genes Bacterianos , Sensibilidade e Especificidade , Especificidade da Espécie , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/normas , Fatores de Tempo
20.
J Agric Food Chem ; 54(18): 6475-81, 2006 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-16939300

RESUMO

The mid- and near-infrared (mid-IR and NIR) spectra of aqueous solutions of glucose and fructose, fructose and galactose, and glucose and galactose were recorded and analyzed by heterospectral two-dimensional correlation spectroscopy (H2D-CS) to determine characteristic NIR wavelengths for each sugar. Fourier self-deconvolution (FSD) was applied to the NIR spectra prior to H2D-CS analysis to help resolve the strongly overlapping sugar absorptions. Examination of the H2D-CS data gave characteristic absorption wavelengths for glucose, fructose, and galactose. The wavelengths identified by H2D-CS were then used to develop multiple linear regression (MLR) calibrations for the quantitative analysis of mixtures of the three sugars in solution. This approach gave comparable results to MLR calibrations based on wavelengths selected by examination of the first- and second-derivative spectra of solutions of the individual sugars.


Assuntos
Frutose/química , Galactose/química , Glucose/química , Soluções/química , Análise Espectral/métodos , Espectrofotometria Infravermelho , Espectroscopia de Infravermelho com Transformada de Fourier
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