RESUMO
Organic nitrates in the atmosphere are associated with photochemical pollution and are the main components of secondary organic aerosols, which are related to haze. An efficient method for determining organic nitrates in atmospheric fine particles (PM2.5) was established using synthesized standards. Four alkyl (C7-C10) nitrates and three aromatic nitrates (tolyl nitrate, phenethyl nitrate, and p-xylyl nitrate) were synthesized and characterized by 1H and 13C nuclear magnetic resonance spectroscopy. The optimal ions for quantifying and confirming the identities of the analytes were identified by analyzing the standards by gas chromatography tandem mass spectrometry. The tandem mass spectrometer was a triple quadrupole instrument. This method can obtain more accurate information of organic nitrates than on-line methods. Spiked recovery tests were performed using three spike concentrations, and the recoveries were 61.0-111.4 %, and the relative standard deviations were < 8.2% for all of the analytes. Limits of detection and quantification were determined, and the linearity of the method for each analyte was assessed. The applicability of the method was demonstrated by analyzing six PM2.5 samples. Overall, 87% of the analytes were detected in the samples. Phenethyl nitrate, heptyl nitrate, and octyl nitrate were detected in every sample. Phenethyl nitrate was found at a higher mean concentration (3.23 ng/m3) than the other analytes.
RESUMO
ABSTRACT Purpose: To investigate ocular surface and meibomian glands in patients with treatment-naive acne vulgaris. Methods: The Ocular Surface Disease Index (OSDI) questionnaire, invasive tear film breakup time, fluorescein staining of the ocular surface, and Schirmer II test were performed for all subjects. Total eyelid and meibomian gland secretion scores were assessed. Non-contact meibography was performed with the Sirius corneal topographic device. Results: The right eyes of 35 patients with acne vulgaris and 35 healthy volunteers were included the study. While the OSDI and staining scores were significantly higher in the acne group than in the control group (p=0.01 and p=0.003, respectively), the invasive tear film breakup time and Schirmer measurements were significantly lower in the acne group (p=0.000 and p=0.003, respectively). The total eyelid and meibomian gland secretion scores were also higher in the acne group than in the control group (p=0.003 and p=0.000, respectively). On the morphological evaluation of the meibomian glands, the thickening, thinning, tortuosity, and presence of ghost areas were statistically significantly more common in the acne vulgaris group than in the control group (p=0.000, p=0.001, p=0.05, and p=0.006, respectively). The percentage of the meibomian gland loss area was significantly high in the acne vulgaris group on both upper and lower meibography. The meibomian gland loss area positively correlated with total eyelid and meibomian gland secretion scores. Conclusion: Acne vulgaris may have a predisposition to meibomian gland dysfunction and ocular surface damage. Early recognition of meibomian gland and ocular surface alterations seems important, especially in acne vulgaris cases for which oral isotretinoin treatment is planned.
RESUMO Objetivo: Todos os indivíduos responderam ao questionário Ocular Surface Disease Index (OSDI) e tiveram avaliados o tempo de ruptura do filme lacrimal pelo método invasivo, a coloração da superfície ocular com fluoresceína e o teste de Schirmer II. Foram ainda avaliados o escore palpebral total e o de secreção das glândulas meibomianas. Foi realizada meibografia sem contato com um dispositivo topográfico corneano Sirius. Métodos: Todos os indivíduos responderam ao questionário Ocular Surface Disease Index (OSDI) e tiveram avaliados o tempo de ruptura do filme lacrimal pelo método invasivo, a coloração da superfície ocular com fluoresceína e o teste de Schirmer II. Foram ainda avaliados o escore palpebral total e o de secreção das glândulas meibomianas. Foi realizada meibografia sem contato com um dispositivo topográfico corneano Sirius. Resultados: Foram incluídos no estudo os olhos direitos de 35 voluntários com acne vulgar e 35 saudáveis. Os escores do Ocular Surface Disease Index e da coloração foram significativamente maiores no grupo com acne em comparação com o grupo controle (p=0,01 e p=0,003, respectivamente), mas o tempo de ruptura do filme lacrimal pelo método invasivo e as medidas do teste de Schirmer II foram significativamente menores (p=0,000 e p=0,003, respectivamente). O escore palpebral total e o escore de secreção das glândulas meibomianas também foram maiores no grupo com acne que no grupo controle (p=0,003 e p=0,000). Na avaliação morfológica das glândulas meibomianas, o espessamento, o afinamento, a tortuosidade e a presença de áreas fantasmas nas glândulas foram mais comuns no grupo acne vulgar que no grupo controle, com significância estatística (p=0,000, p=0,001, p=0,05 e p=0,006 respectivamente). A porcentagem da área de perdas das glândulas meibomianas foi significativamente mais alta no grupo com acne vulgar, tanto na meibografia superior quanto na inferior. A área de perda das glândulas meibomianas demonstrou uma correlação positiva com o escore palpebral total e com o escore de secreção das glândulas meibomianas. Conclusão: A acne vulgar pode levar a uma predisposição para a disfunção das glândulas meibomianas e para danos na superfície ocular. Parece ser importante reconhecer precocemente as alterações das glândulas meibomianas e da superfície ocular, especialmente nos casos de acne vulgar para os quais se planeja o tratamento oral com isotretinoína.