Infrared spectroscopy combined with chemometrics in transflectance mode: An alternative approach in the photodiagnosis of COVID-19 using saliva

The Coronavirus Disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has required the search for sensitive, rapid, specific, and lower-cost diagnostic methods to meet the high demand. The gold standard method of laboratory diagnosis is real-time reverse transcription polymerase chain reaction (RT-PCR). However, this method is costly and results can take time. In the literature, several studies have already described the potential of Fourier transform infrared spectroscopy (FTIR) as a tool in the biomedical field, including the diagnosis of viral infections, while being fast and inexpensive. In view of this, the objective of this study was to develop an FTIR model for the diagnosis of COVID-19. For this analysis, all private clients who had performed a face-to-face collection at the Univates Clinical Analysis Laboratory (LAC Univates) within a period of six months were invited to participate. Data from clients who agreed to participate in the study were collected, as well as nasopharyngeal secretions and a saliva sample. For the development of models, the RT-PCR result of nasopharyngeal secretions was used as a reference method. Absorptions with high discrimination (p < 0.001) between GI (28 patients, RT-PCR test positive to SARS-CoV-2 virus) and GII (173 patients who did not have the virus detected in the test) were most relevant at 3512 cm-1, 3385 cm-1 and 1321 cm-1 after 2nd derivative data transformation. To carry out the diagnostic modeling, chemometrics via FTIR and Discriminant Analysis of Orthogonal Partial Least Squares (OPLS-DA) by salivary transflectance mode with one latent variable and one orthogonal signal correction component were used. The model generated predictions with 100 % sensitivity, specificity and accuracy. With the proposed model, in a single application of an individual's saliva in the FTIR equipment, results related to the detection of SARS-CoV-2 can be obtained in a few minutes of spectral evaluation.

Structural characterization of DNA amplicons by ATR-FTIR spectroscopy as a guide for screening metainflammatory disorders in blood plasma

Attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy is a promising rapid, reagent-free, and low-cost technique considered for clinical translation. It allows to characterize biofluids proteome, lipidome, and metabolome at once. Metainflammatory disorders share a constellation of chronic systemic inflammation, oxidative stress, aberrant adipogenesis, and hypoxia, that significantly increased cardiovascular and cancer risk. As a result, these patients have elevated concentration of cfDNA in the bloodstream. Considering this, DNA amplicons were analyzed by ATR-FTIR at 3 concentrations with 1:100 dilution: (IU/mL): 718, 7.18, and 0.0718. The generated IR spectrum was used as a guide for variable selection. The main peaks in the biofingerprint (1800-900 cm-1) give important information about the base, base-sugar, phosphate, and sugar-phosphate transitions of DNA. To validate our method of selecting variables in blood plasma, 38 control subjects and 12 with metabolic syndrome were used. Using the wavenumbers of the peaks in the biofingerprint of the DNA amplicons, was generated a discriminant analysis model with Mahalanobis distance in blood plasma, and 100 % discrimination accuracy was obtained. In addition, the interval 1475-1188 cm-1 showed the greatest sensitivity to variation in the concentration of DNA amplicons, so curve fitting with Gaussian funcion was performed, obtaining adjusted-R2 of 0.993. PCA with Mahalanobis distance in the interval 1475-1188 cm-1 obtained an accuracy of 96 % and PLS-DA modeling in the interval 1475-1088 cm-1 obtained AUC = 0.991 with sensitivity of 95 % and specificity of 100 %. Therefore, ATR-FTIR spectroscopy with variable selection guided by DNA IR peaks is a promising and efficient method to be applied in metainflammatory disorders.

Prediction of melanin content of Fonsecaea pedrosoi using Fourier transform infrared spectroscopy (FTIR) and chemometrics

Fungal melanin contributes to the survival and virulence of pathogenic fungi, such as Fonsecaea pedrosoi, which is responsible for causing chromoblastomycosis. The objective of this study was to employ Fourier transform infrared spectroscopy (FTIR) to predict the melanin content of F. pedrosoi. The melanin content, in percentage, was previously determined using gravimetry for twenty-six clinical isolates. Quintuplicate spectra of each isolate were obtained using attenuated total reflection (ATR) within the range of 4000 to 650 cm-1. To predict the melanin content, modeling was performed using partial least squares regression (PLS) in the region 1800 - 750 cm-1. Two models were tested: PLS and successive projections algorithms for interval selection in partial least squares (iSPA-PLS). The best modeling results were achieved using iSPA-PLS with one factor. The calibration set exhibited a determination coefficient (R2) of 0.9745 and a root mean square error of cross-validation (RMSECV) of 0.0977. In the prediction set, the R2 value was 0.9711, and the root mean square error of prediction (RMSEP) was 0.0999. Modeling with FTIR and multivariate calibration provides a valuable means of predicting fungal melanin content, which is simpler and more robust, thereby contributing to the advancement of this field of study.

Rapid Classification of Serum from Patients with Paracoccidioidomycosis Using Infrared Spectroscopy, Univariate Statistics, and Linear Discriminant Analysis (LDA)

Paracoccidioidomycosis (PCM) is a systemic mycosis that is diagnosed by visualizing the fungus in clinical samples or by other methods, like serological techniques. However, all PCM diagnostic methods have limitations. The aim of this study was to develop a diagnostic tool for PCM based on Fourier transform infrared (FTIR) spectroscopy. A total of 224 serum samples were included: 132 from PCM patients and 92 constituting the control group (50 from healthy blood donors and 42 from patients with other systemic mycoses). Samples were analyzed by attenuated total reflection (ATR) and a t-test was performed to find differences in the spectra of the two groups. The wavenumbers that had p < 0.05 had their diagnostic potential evaluated using receiver operating characteristic (ROC) curves. The spectral region with the lowest p value was used for variable selection through principal component analysis (PCA). The selected variables were used in a linear discriminant analysis (LDA). In univariate analysis, the ROC curves with the best performance were obtained in the region 1551-1095 cm-1. The wavenumber that had the highest AUC value was 1264 cm-1, achieving a sensitivity of 97.73%, specificity of 76.01%, and accuracy of 94.22%. The total separation of groups was obtained in the PCA performed with a spectral range of 1551-1095 cm-1. LDA performed with the eight wavenumbers with the greatest weight from the group discrimination in the PCA obtained 100% accuracy. The methodology proposed here is simple, fast, and highly accurate, proving its potential to be applied in the diagnosis of PCM. The proposed method is more accurate than the currently known diagnostic methods, which is particularly relevant for a neglected tropical mycosis such as paracoccidioidomycosis.

Immobilization of Horseradish Peroxidase on Ca Alginate-Starch Hybrid Support: Biocatalytic Properties and Application in Biodegradation of Phenol Red Dye

In this study, horseradish peroxidase was extracted, purified, and immobilized on a calcium alginate-starch hybrid support by covalent bonding and entrapment. The immobilized HRP was used for the biodegradation of phenol red dye. A 3.74-fold purification was observed after precipitation with ammonium sulfate and dialysis. An immobilization yield of 88.33%, efficiency of 56.89%, and activity recovery of 50.26% were found. The optimum pH and temperature values for immobilized and free HRP were 5.0 and 50 °C and 6.5 and 60 °C, respectively. The immobilized HRP showed better thermal stability than its free form, resulting in a considerable increase in half-life time (t1/2) and deactivation energy (Ed). The immobilized HRP maintained 93.71% of its initial activity after 45 days of storage at 4 °C. Regarding the biodegradation of phenol red, immobilized HRP resulted in 63.57% degradation after 90 min. After 10 cycles of reuse, the immobilized HRP was able to maintain 43.06% of its initial biodegradative capacity and 42.36% of its enzymatic activity. At the end of 15 application cycles, a biodegradation rate of 8.34% was observed. In conclusion, the results demonstrate that the immobilized HRP is a promising option for use as an industrial biocatalyst in various biotechnological applications.

Immobilization of commercial horseradish peroxidase in calcium alginate-starch hybrid support and its application in the biodegradation of phenol red dye

In this study, horseradish peroxidase (HRP) was immobilized for the first time on Ca alginate-starch hybrid beads and employed for the biodegradation of phenol red dye. The optimal protein loading was 50 mg/g of support. Immobilized HRP demonstrated improved thermal stability and maximum catalytic activity at 50 °C and pH 6.0, with an increase in half-life (t1/2) and enzymatic deactivation energy (Ed) compared to free HRP. After 30 days of storage at 4 °C, immobilized HRP retained 109% of its initial activity. Compared to free HRP, the immobilized enzyme exhibited higher potential for phenol red dye degradation, as evidenced by the removal of 55.87% of initial phenol red after 90 min, which was 11.5 times greater than free HRP. In sequential batch reactions, the immobilized HRP demonstrated good potential efficiency for the biodegradation of phenol red dye. The immobilized HRP was used for a total of 15 cycles, degrading 18.99% after 10 cycles and 11.69% after 15 cycles, with a residual enzymatic activity of 19.40% and 12.34%, respectively. Overall, the results suggest that HRP immobilized on Ca alginate-starch hybrid supports shows promise as a biocatalyst for industrial and biotechnological applications, particularly for the biodegradation of recalcitrant compounds such as phenol red dye.

Detection of metabolic syndrome with ATR-FTIR spectroscopy and chemometrics in blood plasma

Metabolic Syndrome (MetS) is a constellation of 3 or more risk factor (abdominal obesity, high triglycerides, low HDL-c, high blood pressure, and elevated blood glucose) for atherosclerotic cardiovascular disease. Considering these systemic metabolic changes in the biochemical pathways of all biomolecules, Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy is a rapid, low-cost, and reagent-free alternative technique capable of identifying spectral biomarkers that differentiate subjects with MetS from control. In this study, plasma samples from 74 subjects (14 MetS, 60 control) were analyzed on the ATR-FTIR spectrophotometer. The objective was to differentiate subjects with MetS from control with supervised chemometrics modeling (Orthogonal Partial Least Squares-Discriminant Analysis, OPLS-DA). Additionally, the inflammatory status of subjects with MetS and control (supervised by C-reactive protein - CRP, leptin, and cell-free DNA - cfDNA) was verified. The OPLS-DA model achieved 100% sensitivity and specificity in cross-validation. For 1 latent variable (93.4% of variance), RMSECV < 0.002, PRESS CV < 0.0001, and R² > 0.9999 was obtained. Significant spectrochemical differences (p < 0.05) were found between MetS and control subjects in the following biomolecular regions (cm^-1): 1717-1703 [ν(CO) and δ(NH)], 1166-1137 [ν(C-OH) + ν(CO) and ν(CC) + δ(OH) + ν(CO)], 1113-1040 [ν(PO₂^-) and ν(C-OH)], and 1027-1008 [ν(CO) and v(CH₂OH)]. In the OPLS-DA model loadings, amide I [1720-1600 cm^-1, ν(CO)] and amide II [1570-1480 cm^-1, δ(NH) + ν(CH)] had significantly greater weight than all other regions. There was a significant difference in inflammatory status between MetS patient and control (p < 0.05 for CRP and leptin, and p < 0.01 for cfDNA).

Rapid and low-cost liquid biopsy with ATR-FTIR spectroscopy to discriminate the molecular subtypes of breast cancer

Breast cancer (BC) is the most prevalent cancer worldwide. The prognosis and survival of these patients are directly related to the diagnostic stage. Even so, the gold standard screening method (mammography) has a long waiting period, high rates of false positives, anxiety for patients, and consequently delays the diagnosis by core needle biopsy (invasive method). Alternatively, the Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy is a noninvasive, low-cost, rapid, and reagent-free technique that generates the spectral metabolomic profile of biomolecules. This makes it possible to assess systemic repercussions, such as the BC carcinogenesis process. Blood plasma samples (n = 56 BC and n = 18 controls) were analyzed in the spectrophotometer in the ATR-FTIR mode. For the exploratory analysis of the data, interval Principal Component Analysis (iPCA) was used, and for predictive chemometric modeling, the Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) algorithm with validation by leave-one-out cross-validation. iPCA in the region of 1118-1052 cm^-1 (predominantly DNA/RNA bands) showed significant clustering of molecular subtypes and control. The OPLS-DA model achieved 100% accuracy with only 1 latent variable and Root Mean Square Error of Cross-Validation (RMSECV) < 0.005 for all molecular subtypes and control. The wavenumbers (cm^-1) with the highest iPCA peaks (loadings: 1117, 1089, 1081, 1075, 1057, and 1052) were used as input to MANOVA (Wilks' Lambda, p < 0.001 between molecular subtypes and control). The rapid and low-cost detection of BC molecular subtypes by ATR-FTIR spectroscopy would plausibly allow initial screening and clinical management, improving prognosis, reducing mortality and costs for the health system.

Discrimination of dyslipidemia types with ATR-FTIR spectroscopy and chemometrics associated with multivariate analysis of the lipid profile, anthropometric, and pro-inflammatory biomarkers

BACKGROUND

Obesity, dyslipidemia, and low-grade inflammatory state form a triad of self-sustaining metabolic dysfunction. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is a simple, rapid, and non-destructive technique that generates spectral fingerprints of biomolecules that can be correlated with metabolic changes. We verified the efficiency of ATR-FTIR spectroscopy in blood plasma (n = 74) to discriminate the types of dyslipidemias and suggest metabolic inflammatory changes.

METHODS

Principal Component Analysis (PCA) was performed on the biochemical and anthropometric data to verify whether the dyslipidemia types share a similar biochemical profile plausible of discrimination in chemometric modeling. To discriminate the types of dyslipidemias based on spectral data, Orthogonal Partial Least-Squares Discriminant Analysis (OPLS-DA) was used and validated with leave-one-out cross-validation.

RESULTS

Although no significant difference was obtained between the types of dyslipidemia and normal subjects by CRP, leptin, and cfDNA, there was a significant difference between normal subjects vs combined hyperlipidemia (CH) + hypercholesterolemia (HCL) + hypertriglyceridemia (HTG) (p < 0.05) by the 1245 cm^-1 peak [ν_as(PO₂^-)] (possible indication of chronic inflammation by increased cfDNA). The area under the curve of the region between 1770 and 1720 cm^-1 was significantly increased for CH in relation to other dyslipidemias and normal subjects. Furthermore, there were significant differences for the main representative peaks of lipids, proteins, carbohydrates, and nucleic acids between the types of dyslipidemias and between the types of dyslipidemias and normal subjects. The OPLS-DA model achieved 100 % accuracy with 1 latent variable and Standard Error of Cross-Validation (SECV) < 0.004 for all types of dyslipidemia  and the control group.

CONCLUSIONS

Our results suggest that ATR-FTIR spectroscopy associated with chemometric modeling is a plausible applicant for screening the types of dyslipidemias. However, more extensive studies should be conducted to verify the real applicability in clinical analysis laboratories or medical clinics.

Saliva may predict quality of life in psoriasis as measured by Fourier transform infrared spectroscopy (FTIR) and chemometrics

BACKGROUND

Psoriasis is a chronic skin disease, with several comorbidities, such as psoriatic arthritis, inflammatory bowel disease, metabolic syndrome, and impaired quality of life and work activity. The Dermatology Life Quality Index (DLQI) is the most commonly used quality of life index in psoriatic patients, as it is a marker of severe disease. This study evaluated the association between salivary Fourier transform Infrared Spectroscopy (FTIR) metabolic fingerprints and severity of psoriasis as measured by DLQI, using chemometric algorithms.

MATERIALS AND METHODS

Saliva was collected from 56 (27 with DLQI ≤ 10 [GI]; 29 with DLQI > 10 [GII]) psoriatic patients diagnosed and assessed by DLQI for disease severity by a dermatologist and analyzed by the transflectance technique in mid-infrared. Hierarchic cluster analysis (HCA), principal component analysis (PCA), orthogonal partial least squares discriminant analysis (OPLS-DA) and orthogonal partial least squares (OPLS) algorithms were used to associate salivary FTIR spectra with the respective DLQI scores.

RESULTS

Second derivative (2D) discriminated GI and GII at 2522 cm^-1 (p < 0.0001). HCA and PCA partially discriminated GI from GII at 4000-450 cm^-1 (p = 0.042 and 0.00821, respectively). Data processing with 1^st derivative (1D), 3 latent variables (LV) and 1 orthogonal signal correction (OSC) component at 2550-1801 cm^-1 generated an FTIR/OPLS-DA model with 100% accuracy to classify the severity of psoriasis, and an FTIR/OPLS model to quantify DLQI (range 0-28) with high performance: root mean square error of prediction (RMSEP) < 0.01 and coefficient of determination (R²) > 0.9999.

CONCLUSIONS

Salivary FTIR combined with chemometric algorithms such as OPLS-DA and OPLS can be used as a clinical tool to classify or predict the severity of psoriasis according to DLQI in patients with confirmed psoriasis.

QUANTIFICAÇÃO MAIS LIMPA DE FIBRAS EM BISCOITOS SALGADOS TIPO CRACKER ATRAVÉS DE FTIR E QUIMIOMETRIA

Neste trabalho apresentamos a implantação e a otimização de um novo método mais limpo baseado em Espectroscopia no Infravermelho com Transformada de Fourier (FTIR) e quimiometria para a quantificação de fibras em biscoitos salgados tipo cracker. Para tanto, 60 amostras de biscoitos salgados tipo cracker oriundos do comércio local de Santa Cruz do Sul (RS, Brasil) foram trituradas e submetidas à análise de fibras por digestão ácida e alcalina segundo o método de referência. As amostras foram também analisadas pela técnica de Reflectância Total Atenuada (ATR) na faixa de 4000-650 cm-1. O conjunto de espectros foi modelado via regressão por mínimos quadrados parciais ortogonais (OPLS) com os dados do método de referência em diferentes faixas espectrais e pré-processamentos. Um modelo ATR/OPLS otimizado foi obtido na faixa de 4000-650 cm-1 com 2 variáveis latentes e dados sem pré-processamento, transformados pela 1ª derivada e por 1 componente de correção de sinal ortogonal. A validação cruzada retornou um coeficiente de determinação de 0,9999 e um RMSECV comprovando assim a validade do método FTIR com quimiometria para esta finalidade    

Rapid classification of chromoblastomycosis agents genera by infrared spectroscopy and chemometrics supervised by sequencing of rDNA regions

Chromoblastomycosis (CBM) is a skin and subcutaneous infection caused by species of seven fungal genera. Identification of CBM species is performed by DNA sequencing of one or more genes, which becomes a time-consuming work. Fourier Transform Infrared Spectroscopy (FTIR) has been used for the identification of other microorganisms, however, only one CBM genus was evaluated by FTIR analysis to date. Therefore, the study is aimed to differentiate the CBM agents for identification at genera level using FTIR supervised by Internal Transcribed Spacer (ITS) rDNA region. Seventy-seven isolates of the main five CBM genera were prepared for Attenuated Total Reflection FTIR (ATR-FTIR) with a new methodology using slices of dry fungus in glass fixing-modeling proposed in this study. The algorithm Hierarchical Cluster Analysis (HCA) was used to analyze the differences and similarities between species through the spectra. Orthogonal Partial Least Square Discriminant Analysis (OPLS-DA) allowed to correctly classify all samples of five CBM genera. The ATR-FTIR/OPLS-DA models highlighted important contributions of regions attributed to NH and OH stretching, amide I of proteins, polysaccharides bands and fingerprint region for the complete differentiation of the genera investigated. Thus, FTIR can be a fast and inexpensive alternative for identification of CBM agents.

Prediction of itraconazole minimum inhibitory concentration for Fonsecaea pedrosoi using Fourier Transform Infrared Spectroscopy (FTIR) and chemometrics

Fonsecaea pedrosoi is one of the main agents of chromoblastomycosis, a chronic subcutaneous mycosis. Itraconazole (ITC) is the most used antifungal in its treatment, however, in vitro antifungal susceptibility tests are important to define the best therapy. These tests are standardized by the Clinical and Laboratory Standards Institute (CLSI), but these protocols have limitations such as the high complexity, cost and time to conduct. An alternative to in vitro susceptibility test, which overcomes these limitations, is FTIR. This study determined the minimum inhibitory concentration (MIC) of itraconazole for F. pedrosoi, using FTIR and chemometrics. The susceptibility to ITC of 36 strains of F. pedrosoi was determined according to CLSI and with the addition of tricyclazole (TCZ), to inhibit 1,8-dihydroxynaphthalene (DHN)-melanin biosynthesis. Strains were grown in Sabouraud agar and prepared for Attenuated Total Reflection (ATR)/FTIR. Partial least squares (PLS) regression was performed using leave-one-out cross-validation (by steps of quintuplicates), then tested on an external validation set. A coefficient of determination (R²) higher than 0.99 was obtained for both the MIC-ITC and MIC-ITC+TCZ ATR/PLS models, confirming a high correlation of the reference values with the ones predicted using the FTIR spectra. This is the first study to propose the use of FTIR and chemometric analyses according to the M38-A2 CLSI protocol to predict ITC MICs of F. pedrosoi. Considering the limitations of the conventional methods to test in vitro susceptibility, this is a promising methodology to be used for other microorganisms and drugs.

Discrimination of healthy and colorectal cancer patients using FTIR and PLS-DA

Spectroscopic methods have already been used as effective tools in several studies involving the detection of cancer. Fourier transform infrared spectroscopy (FTIR) has already been applied in the discrimination of cancer cells and tissues or blood of patients with the disease, observing that this technique requires the use of chemometric algorithms to obtain such results. The aim of this study was to employ a partial least squares discriminant analysis (PLS-DA) with FTIR data in the discrimination of plasma samples from patients with colorectal cancer (RCC) and healthy individuals. Multivariate analysis was performed using PLS-DA of the sample triplicates (n=90) with different types of processing. The best PLS-DA condition was obtained using the 1st derivative, 1 orthogonal signal correction (OSC) and no pre-processing. With 1 factor only, the model presented a mean square error of cross-validation (RMSECV) of 0.0004 and coefficient of determination (r^2) of 1.0000. The accuracy, precision and sensitivity of the model were 100%.

Síntese e avaliação de azoderivado de 2-fenilbenzoxazol como substrato fluorogênico na diferenciação de Candida spp

Neste estudo foram sintetizados três derivados de 2-fenilbenzoxazol (2FBO) funcionalizados com a função azo: (2’-hidroxi-5’-fenilazofenil)benzoxazol (HFAZBO), 2-(2’-hidroxi-5’-(4’’-carboxi)fenilazofenil)benzoxazol (HFAZBO-CO2H) e 2-(2’-hidroxi-5’-(4’’-nitro)fenilazofenil)benzoxazol (HFAZBO-NO2).Os compostos foram utilizados como substratos fluorogênicos para agentes de infecção urinária, representantes de Candida spp., para explorar suas características metabólicas. A caracterização estrutural dos compostos foi realizada por meio de Espectroscopia de Absorção Molecular no Infravermelho com transformada de Fourier (FT-IR) e por determinação da faixa de fusão. Os ensaios fluorogênicos foram realizados em espécies de Candida spp.: Candida albicans ATCC 10231, Candida famata RL38, Candida glabrata 06130L, Candida glabrata RL43, Candida glabrata 0030L, Candida guilliermondii TH07, Candida krusei ATCC 6258, Candida krusei 0037L, Candida parapsilosis (RL33), Candida parapsilosis (RL38), Candida stellatoidea (9875), Candida stellatoidea (3613), Candida tropicalis ATCC 750. Não foi observada alteração sob luz uv nas leveduras testadas. Do mesmo modo, o extrato obtido a partir das colônias não apresentou fluorescência sob luz uv. Dessa forma, faz-se necessário desenvolver novos estudos que avaliem a função metabólica de Candida spp. a partir da biotransformação levando a liberação de moléculas fluorescentes.

Resíduos citrícolas: uma breve revisão

O Brasil é um dos países que mais desperdiçam alimentos, como frutas e hortaliças. A procura por alimentos saudáveis aumenta e o desperdício segue o mesmo caminho. A população está investindo mais em alimentos saudáveis e atenta às suas propriedades funcionais, a fim de prevenir e diminuir problemas de saúde. A produção de farinhas a partir da casca e polpa de mandarina é descrita como forma de reaproveitamento de resíduos provenientes de raleio. Os citrus são conhecidos como antioxidantes, prevenindo doenças e conferindo homeostasia às células. São ricos em compostos bioativos como os compostos fenólicos que conferem cor e sabor ao fruto, e os flavonoides com ação anti-inflamatória, antialergênica, ambos responsáveis pela atividade antioxidante quando consumidos. O presente trabalho de revisão tem como enfoque o desperdício de alimentos, reaproveitamento de resíduos citrícolas, a importância de compostos bioativos como compostos fenólicos e flavonoides, bem como métodos analíticos para a quantificação dos mesmos.

Uma abordagem sobre a determinação de atividade antioxidante e fenóis totais por FT-IR e quimiometria em alimentos

Os componentes bioativos presentes nos alimentos são conhecidos por suas propriedades nutracêuticas sendo necessário desenvolver metodologias analíticas capazes de determinar e quantificar tais compostos. No entanto, os métodos disponíveis para tais análises que são essencialmente baseados em reações colorimétricas, demandam tempo e implicam em considerável geração de custos, decorrente do alto valor dos reagentes, e de resíduos. Com isso, as técnicas moleculares como a Espectroscopia de Absorção Molecular no Infravermelho com transformada de Fourier (FT-IR) aliada à quimiometria surgem como técnicas complementares para a análise de dados multivariados provenientes das amostras por meio de modelos de predição. Esta revisão aborda uma atualização referente ao período de 2013 a 2018 no uso de modelos quimiométricos como complemento à análise de atividade antioxidante e conteúdo fenólico total em alimentos sólidos. Em razão de a técnica ser propícia para atender aos requisitos de consciência ambiental e economia de custos sem prejuízo nos resultados de pesquisa, verifica-se a importância do desenvolvimento de métodos à base de FT-IR associados a recursos quimiométricos para análise de componentes alimentares.

[Evaluation of the quality of air in a surgical center of a hospital in the south of Brazil]

Objective The aim of this study was to evaluate the quality of air in surgical centre rooms of a hospital in the South of Brazil. Methods An evaluation of the parameters of comfortability (temperature, luminosity, concentration of carbon dioxide and relative humidity), microbiological analysis and chromatographic of the particulate material present in the filters of air conditioners was carried out. Results Regarding the aspects of comfortability, three surgical rooms did not present temperature in accordance to the current legislation, but were found within the ideal patterns in other environmental factors. In the analysis of particulate material, a larger number of fungal bio-aerosols of viscous colonies was obtained than filamentous. Conclusion It was found that the main aspects related to the quality of air in the hospital being studied are being accomplished; however there is a need of modifying building aspects in the surgical rooms in order to reduce the possibility of contamination by air and decrease the concentration of carbon dioxide in the environment.

Desenvolvimento de primers para identificação e diferenciação de espécies de Candida em secreção vaginal por PCR em tempo real (qPCR)

Infecções fúngicas são cada vez mais frequentes, principalmente relacionadas ao sistema geniturinário e causadas por Candida spp. A PCR mostra-se promissora para o diagnóstico e para sua aplicação faz-se necessário o desenvolvimento de primers. Para isso obteve-se sequências da região ITS do rDNA 18S de 5 espécies de Candida, alinhou-se e verificou-se os tamanhos dos amplicons e as Tms teóricas. Cepas padrão e cepas cultivadas foram utilizadas como referência. Além disso, 67 amostras de DNA de secreção vaginal foram submetidas a qPCR e os resultados foram confirmados em gel de agarose 2%. Os testes in silico demonstraram a capacidade do par de primers em diferenciar as cinco espécies, o que foi confirmado após a amplificação das cepas padrão e de amostras de secreção vaginal, identificadas em 20 amostras. O limite de detecção foi de 58 células/mL para as cepas padrão de C. albicans e C. tropicalis e 29 células/mL para C. parapsilosis. A sensibilidade da qPCR frente ao teste de crescimento microbiológico foi de 68%, com especificidade de 90%. A técnica possui potencial de diagnóstico, porém precisa ser otimizada para testes quantitativos.

Refletindo sobre o processo de institucionalização do idoso

Justificativa e Objetivo: O envelhecimento é um processo natural que vem obtendo maior relevância e preocupação a partir do aumento considerável da expectativa de vida da população. É observado que atualmente ocorre um aumento de estudos relacionados com o cuidado do idoso, em especial daquele que se encontra em uma Instituição de Longa Permanência (ILP). O objetivo deste artigo é discutir sobre o processo de institucionalização do idoso e sobre as características do grupo familiar e perfil da população internada nestas instituições. Conteúdo: O aumento da população idosa ao longo do tempo é acompanhado por modificações na estrutura e rotina familiar, fazendo com que, para muitas famílias, torne-se inviável atender as necessidades do idoso. Deste modo, as Instituições de Longa Permanência para Idosos (ILPIs) constituem-se em uma alternativa para suprir estas necessidades, proporcionando cuidado amplo pelo trabalho de equipe multidisciplinar. No entanto, deve-se ter uma atenção especial, para que não ocorra uma quebra no vínculo familiar do idoso, visto que a família é uma ferramenta essencial na qualificação do cuidado. Conclusão: É fundamental abandonar o conceito de que ao ingressar nas ILPIs o idoso está abandonado e desamparado, pois com a mudança na rotina familiar, a implantação da Política Nacional do Idoso e o aprimoramento das instituições, esta tornou-se uma alternativa importante para o bem estar do idoso, permitindo acesso a uma assistência que, muitas vezes, não receberia em seu ambiente familiar, sendoimportante a manutenção do vínculo familiar, pois constitui-se em importante ferramenta para a qualidade de vida do idoso.

Identificação de três espécies de Candida por PCR em tempo real

Infecções causadas por leveduras do gênero Candida são muito prevalentes. A correta identificação da espécie é uma etapa fundamental para a escolha do tratamento adequado, mas os métodos tradicionais apresentam limitações. Assim, o objetivo do presente trabalho foi padronizar uma reação de PCR em tempo real (qPCR) para identificação de Candida albicans, C. glabrata e C. parapsilosis, que é uma técnica mais rápida para o diagnóstico. As amostras utilizadas consistiram em DNA extraído de cepas padrão. Realizou-se uma qPCR com SybrGreen® e diluições seriadas das amostras, com as mesmas condições do trabalho em que foram descritos os primers utilizados. Nesse ensaio os resultados foram satisfatórios apenas para C. parapsilosis, pois em C. albicans e C. glabrata, apesar de ocorrer a amplificação da sequência alvo, houve formação de produtos inespecíficos nas reações. Foi feita então uma análise in silico dos primers, que sugeriu não haver problemas significativos em sua construção, contudo encontrou-se alguns problemas de especificidade para C. parapsilosis e C. glabrata. Conclui-se que são necessários estudos posteriores para desenvolvimento e validação de novos primers que mostrem maior sensibilidade e especificidade para as espécies patogênicas.

The influence of active and passive smoking on the cardiorespiratory fitness of adults

Background: The aim of this study was to analyze the influence of active and passive smoking on cardiorespiratory responses in asymptomatic adults during a sub-maximal-exertion incremental test. Methods: The participants (n = 43) were divided into three different groups: active smokers (n = 14; aged 36.5 ± 8 years), passive smokers (n = 14; aged 34.6 ± 11.9 years) and non-smokers (n = 15; aged 30 ± 8.1 years). They all answered the Test for Nicotine Dependence and underwent anthropometric evaluation, spirometry and ergospirometry according to the Bruce Treadmill Protocol. Results: VO2max differed statistically between active and non-smokers groups (p < 0.001) and between non-smokers and passive group (p=0.022). However, there was no difference between the passive and active smokers groups (p=0.053). Negative and significant correlations occurred between VO2max and age (r = − 0.401, p = 0.044), percentage of body fat (r = − 0.429, p = 0.011), and waist circumference (WC) (r = − 0.382, p = 0.025). Conclusion: VO2max was significantly higher in non-smokers compared to active smokers and passive smokers. However, the VO2max of passive smokers did not differ from active smokers.

The influence of active and passive smoking on the cardiorespiratory fitness of adults

BACKGROUND

The aim of this study was to analyze the influence of active and passive smoking on cardiorespiratory responses in asymptomatic adults during a sub-maximal-exertion incremental test.

METHODS

The participants (n = 43) were divided into three different groups: active smokers (n = 14; aged 36.5 ± 8 years), passive smokers (n = 14; aged 34.6 ± 11.9 years) and non-smokers (n = 15; aged 30 ± 8.1 years). They all answered the Test for Nicotine Dependence and underwent anthropometric evaluation, spirometry and ergospirometry according to the Bruce Treadmill Protocol.

RESULTS

VO2max differed statistically between active and non-smokers groups (p < 0.001) and between non-smokers and passive group (p=0.022). However, there was no difference between the passive and active smokers groups (p=0.053). Negative and significant correlations occurred between VO2max and age (r = - 0.401, p = 0.044), percentage of body fat (r = - 0.429, p = 0.011), and waist circumference (WC) (r = - 0.382, p = 0.025).

CONCLUSION

VO2max was significantly higher in non-smokers compared to active smokers and passive smokers. However, the VO2max of passive smokers did not differ from active smokers.

Application of 6-nitrocoumarin as a substrate for the fluorescent detection of nitroreductase activity in Sporothrix schenckii

Introduction

Sporothrix schenckii is a thermal dimorphic pathogenic fungus causing a subcutaneous mycosis, sporotrichosis. Nitrocoumarin represents a fluorogenic substrate class where the microbial nitroreductase activity produces several derivatives, already used in several other enzyme assays. The objective of this study was the analysis of 6-nitrocoumarin (6-NC) as a substrate to study the nitroreductase activity in Sporothrix schenckii.

Methods

Thirty-five samples of S. schenckii were cultivated for seven, 14 and 21 days at 35 °C in a microculture containing 6-nitrocoumarin or 6-aminocoumarin (6-AC) dissolved in dimethyl sulfoxide or dimethyl sulfoxide as a negative control, for posterior examination under an epifluorescence microscope. The organic layer of the seven, 14 and 21-day cultures was analyzed by means of direct illumination with 365 nm UV light and by means of elution on G silica gel plate with hexane:ethyl acetate 1:4 unveiled with UV light.

Results

All of the strains showed the presence of 6-AC (yellow fluorescence) and 6-hydroxylaminocoumarin (blue fluorescence) in thin layer chromatography, which explains the green fluorescence observed in the fungus structure.

Conclusion

The nitroreductase activity is widely distributed in the S. schenckii complex and 6-NC is a fluorogenic substrate of easy access and applicability for the nitroreductase activity detection.

Lipolytic activity of chromoblastomycosis agents measured by infrared spectroscopy and chemometric methods

The lipase activity of nine strains of six chromoblastomycosis agents (Fonsecaea pedrosoi, Phialophora verrucosa, Cladophialophora bantianum, Cladophialophora carrionii, Rhinocladiela aquaspersa and Exophiala jeanselmei) grown on solid medium was investigated using Fourier transform infrared spectroscopy and hierarchical clustering analysis. The data was quantified by p-nitrophenyl palmitate assay using partial least squares (PLS) regression. These methods allowed the correlation of six genera and species within the 1230-1650 and 2800+3000 cm(-1) spectral ranges among strains grown for 14 days from their respective lipolytic activity with RMSEV=0.048 and R2val=0.95 and ten latent variables. The lipolytic activity also was predicted using PLS models with 1230-1650 and 2800-3000 cm(-1) and 900-1450 cm(-1) spectral ranges for strains grown for 21 days. The separate analysis of F. pedrosoi strains yielded a prediction model for biomass at 21 days with RMSEV=0.065 and R2val=0.95 with eight latent variables using (1100-1300)+(1330-1460)+(1550-1650) cm(-1) spectral regions The best model obtained with the clustering of P. verrucosa, C. bantianum, C. carrionii, R. aquaspersa and E. jeanselmei strains was constructed with the same spectral ranges, but with RMSEV=0.074 and R2val=0.94 and ten latent variables. Infrared spectroscopy is suitable for the quantitation of extracellular lipase activity linked to the biomass of chromoblastomycosis agents.

Secretion of five extracellular enzymes by strains of chromoblastomycosis agents

The gelatinase, urease, lipase, phospholipase and DNase activities of 11 chromoblastomycosis agents constituted by strains of Fonsecaea pedrosoi, F. compacta, Phialophora verrucosa, Cladosporium carrionii, Cladophialophora bantiana and Exophiala jeanselmei were analyzed and compared. All strains presented urease, gelatinase and lipase activity. Phospholipase activity was detected only on five of six strains of F. pedrosoi. DNase activity was not detected on the strains studied. Our results indicate that only phospholipase production, induced by egg yolk substrate, was useful for the differentiation of the taxonomically related species studied, based on their enzymatic profile.

Delayed-type hypersensitivity response to crude and fractionated antigens from Fonsecaea pedrosoi CMMI 1 grown in different culture media

Chromoblastomycosis is a subcutaneous fungal disease caused by dematiaceous fungi, especially by Fonsecaea pedrosoi, regarded as its major causative agent in Brazil. In recent years there has been a decline in the use of skin testing for delayed-type hypersensitivity (DTH) in epidemiological surveys of fungal infections, mainly because of the unpredictability of positive reactions and lack of specificity of the antigens used. The aim of the present study was to assess delayed-type skin tests in guinea pigs experimentally infected with F. pedrosoi using exoantigens prepared from two culture filtrates. Sixteen adult male guinea pigs were inoculated intratesticularly with fungal cells and submitted to sensitivity assays 4 weeks after inoculation. They received an intradermal injection with crude and fractionated antigens from Alviano's and Smith's cultures, and were assessed 24 and 48 h thereafter. Except for one animal, all of them had positive indurations after 48 h. There were no statistical differences between the measurements at 24 and 48 h for each exoantigen used, neither among the induration measurements at 48 h when different preparations were compared. Our results suggest that a delayed-type skin test using antigens produced in synthetic media may be useful for the assessment of primary exposure to chromoblastomycosis.