Effect of oxidation on the structure of human low- and high-density lipoproteins.

This work presents a controlled study of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) structural changes due to in vitro oxidation with copper ions. The changes were studied by small-angle x-ray scattering (SAXS) and dynamic light scattering (DLS) techniques in the case of LDL and by SAXS, DLS, and Z-scan (ZS) techniques in the case of HDL. SAXS data were analyzed with a to our knowledge new deconvolution method. This method provides the electron density profile of the samples directly from the intensity scattering of the monomers. Results show that LDL particles oxidized for 18 h show significant structural changes when compared to nonoxidized particles. Changes were observed in the electrical density profile, in size polydispersity, and in the degree of flexibility of the APO-B protein on the particle. HDL optical results obtained with the ZS technique showed a decrease of the amplitude of the nonlinear optical signal as a function of oxidation time. In contrast to LDL results reported in the literature, the HDL ZS signal does not lead to a complete loss of nonlinear optical signal after 18 h of copper oxidation. Also, the SAXS results did not indicate significant structural changes due to oxidation of HDL particles, and DLS results showed that a small number of oligomers formed in the sample oxidized for 18 h. All experimental results for the HDL samples indicate that this lipoprotein is more resistant to the oxidation process than are LDL particles.

Impact of pre-analytical errors on costs of clinical analysis laboratory / Impacto nos custos por erros pré-analíticos em laboratório de análises clínicas

ABSTRACT Introduction: Currently, it is well known that quality assurance systems in healthcare organizations are constantly evolving. Quality improvements can reduce costs by avoiding repetition of exams, which results in a waste of time and money for the company, as well as customer and physician dissatisfaction. Objective: To quantify the cost that errors in the pre-analytical phase generate for the laboratory using the collection indicators, direct material cost, and operating cost. Materials and methods: The database of a large laboratory in the city of Porto Alegre, Rio Grande do Sul, was analyzed between January 2013 and July 2014. Results: A total cost of R$ 23,330.71 spent on recollections was obtained. Discussion: Management cost is committed to efficiency in reducing expenses, through studies and analyzes aimed at changing management and conduct processes. Conclusion: Cost management is necessary in any company because in the case where it fails to be carried out, besides the being able to bring the institution down to bankrupt, it brings negative costs, as well as impacts customers and physician's satisfaction.

RESUMEN Introducción: Actualmente, llama atención que los sistemas de garantía de calidad en organizaciones sanitarias están en constante evolución. Las mejoras en la calidad pueden reducir los costos, evitando la repetición de pruebas, que genera una pérdida de tiempo y dinero para la empresa, así como la insatisfacción de clientes y médicos. Objetivo: Cuantificar el costo que los errores en la fase preanalítica generan para el laboratorio, utilizando los indicadores de nueva extracción, el costo con material directo y el costo de operación. Materiales y métodos: Se analizó la base de datos de un gran laboratorio en la ciudad de Porto Alegre, Rio Grande do Sul, entre enero de 2013 y julio de 2014. Resultados: Obtuvimos un costo total de R$ 23.330,71 gastados en tomas repetidas. Discusión: El costo de gestión se compromete con la eficiencia en la reducción de gastos, mediante estudios y análisis orientados a cambiar los procesos de gestión y conducción. Conclusión: La gestión de costos es necesaria en cualquier empresa, porque si no se hace, además de poder llevar a la institución a la quiebra, trae costos negativos, así como impactos en la satisfacción de clientes y médicos.

RESUMO Introdução: Atualmente, é notório que os sistemas de garantia da qualidade em organizações de assistência à saúde estão em constante evolução. As melhorias na qualidade podem reduzir os custos, evitando a repetição de exames, que gera desperdício de tempo e dinheiro para a empresa, bem como insatisfação do cliente e médico. Objetivo: Quantificar o custo que os erros na fase pré-analítica geram para o laboratório, utilizando os indicadores de recoleta, o custo com material direto e o custo de operação. Materiais e métodos: O banco de dados de um laboratório de grande porte da cidade de Porto Alegre, Rio Grande do Sul, foi analisado entre janeiro de 2013 e julho de 2014. Resultados: Obtivemos um total de R$ 23.330,71 gastos com as recoletas. Discussão: O custo gerencial compromete-se com a eficiência para redução dos gastos, por meio de estudos e análises voltados para mudanças de processos de administração e conduta. Conclusão: O gerenciamento de custo é necessário em qualquer empresa, pois, caso não seja realizado, além de poder levar a instituição à falência, traz custos negativos, assim como impactos na satisfação de clientes e médicos.

Non-linear Optical Responses of Low-Density Lipoprotein are Associated with Intima-Media Thickness of Carotid Artery in Athletes.

We investigated the association between the degree of oxidative modification of LDL particles by non-linear optical response of LDL (Z-scan technique) and the presence of subclinical atherosclerosis in different segments of the carotid artery. We recruited high-intensity athlete runners (n = 44) and controls (n = 51) to participate in the study. The carotid intima-media thickness (cIMT), interleukin 10 (IL-10), TNF-alpha, and the non-linear optical responses of LDL particle (Z-scan) were assessed. In athletes, the mean cIMT differed between genders, with higher values observed in female athletes compared to male athletes (P < 0.05). Higher mean values for cIMT were seen in the right carotid arteries of female athletes as compared to female controls (P < 0.05). Higher levels of TNF-alpha and IL-10 were found in athletes (P < 0.05). Yet, ΔΓpv (transmittance curve) of Z-scan in athletes was higher than in the non-athletes, indicating less oxidation in LDL particles of athletes (P < 0.05). There was an inverse association between the ΔΓpv and cIMT in the right internal carotid segments (ß = -0.163, P < 0.05) in all subjects, and between the VO2max and the mean cIMT (ß = -0.003, P < 0.05) in male subjects. The present study shows that the Z-scan technique enabled to detect less oxidative modifications in LDL particles from athletes. This effect was associated with cIMT in a gender-dependent mode.

Behavior of the thermal diffusivity of native and oxidized human low-density lipoprotein solutions studied by the Z-scan technique.

Modifications in low-density lipoprotein (LDL) have emerged as a major pathogenic factor of atherosclerosis, which is the main cause of morbidity and mortality in the western world. Measurements of the heat diffusivity of human LDL solutions in their native and in vitro oxidized states are presented by using the Z-Scan (ZS) technique. Other complementary techniques were used to obtain the physical parameters necessary to interpret the optical results, e.g., pycnometry, refractometry, calorimetry, and spectrophotometry, and to understand the oxidation phase of LDL particles. To determine the sample's thermal diffusivity using the thermal lens model, an iterative one-parameter fitting method is proposed which takes into account several characteristic ZS time-dependent and the position-dependent transmittance measurements. Results show that the thermal diffusivity increases as a function of the LDL oxidation degree, which can be explained by the increase of the hydroperoxides production due to the oxidation process. The oxidation products go from one LDL to another, disseminating the oxidation process and caring the heat across the sample. This phenomenon leads to a quick thermal homogenization of the sample, avoiding the formation of the thermal lens in highly oxidized LDL solutions.

Interobserver variability in the diagnosis of anal cancer precursor lesions: study of the usual scenario.

OBJECTIVE: To assess interobserver variability in the diagnosis of anal cancer precursor lesions in the usual scenario of a service consisting of pathologists without previous experience in the diagnosis of these lesions. METHODS: Five hundred and two anal specimens taken from 372 HIV-positive and HIV-negative patients were analyzed at the Pathology Department of the Tropical Medicine Foundation of Amazonas by three pathologists with extensive experience in the diagnosis of infectious and tropical diseases, but without significant prior experience in the diagnosis of anal cancer precursor lesions. The individual readings of each pathologist were compared to the one following the consensus diagnosis in shared optical microscope by kappa statistics. RESULTS: The absolute agreement between each individual diagnosis and corresponding consensus was poor (kappa = -0.002). Considering only the positive or negative results for anal squamous intraepithelial lesions, we obtained a fair agreement between observers (kappa = 0.35), while the agreement was moderate when the histopathological findings were considered positive or negative for high-grade squamous intraepithelial lesion or cancer (kappa = 0.52). CONCLUSION: The interobserver variability in histopathologic diagnosis of anal cancer and its precursor lesions among pathologists with little experience in the area is such that the diagnoses in this field and this scenario should always be a consensus.

Variabilidade interobservadores no diagnóstico de lesões precursoras do câncer anal: estudo do cenário habitual / Interobserver variability in the diagnosis of anal cancer precursor lesions: study of the usual scenario

OBJETIVO: Analisar a variabilidade interobservadores no diagnóstico de lesões precursoras do câncer anal no cenário mais comum de um serviço constituído por patologistas sem experiência prévia no diagnóstico destas lesões. MÉTODOS: Quinhentas e duas lâminas histopatológicas com espécimes anais retirados de 372 pacientes HIV-positivos e HIV-negativos foram analisadas no Departamento de Patologia da Fundação de Medicina Tropical do Amazonas por três patologistas com ampla experiência no diagnóstico de doenças tropicais e infecciosas, mas sem experiência prévia importante no diagnóstico de lesões precursoras do câncer anal. As leituras individuais de cada patologista foram comparadas com a que se seguiu a diagnóstico de consenso em microscópio de ótica compartilhada. Os diagnósticos individuais foram confrontados com os de consenso mediante análise da estatística kappa. RESULTADOS: A concordância absoluta entre cada diagnóstico individual e o de consenso correspondente foi ruim (kappa=-0,002). Considerando os resultados apenas positivos ou negativos para lesões intraepiteliais escamosas anais, obteve-se concordância regular entre os observadores (kappa=0,35), enquanto que a concordância foi moderada quando os resultados histopatológicos foram considerados positivos ou negativos para lesão intraepitelial de alto grau ou câncer (kappa=0,52). CONCLUSÃO: A variabilidade interobservadores no diagnóstico histopatológico do câncer anal e de suas lesões precursoras entre patologistas sem grande experiência na área, apesar de experts em outras, é tal que os diagnósticos neste campo e neste cenário comum devem sempre ser de consenso.

OBJECTIVE: To assess interobserver variability in the diagnosis of anal cancer precursor lesions in the usual scenario of a service consisting of pathologists without previous experience in the diagnosis of these lesions. METHODS: Five hundred and two anal specimens taken from 372 HIV-positive and HIV-negative patients were analyzed at the Pathology Department of the Tropical Medicine Foundation of Amazonas by three pathologists with extensive experience in the diagnosis of infectious and tropical diseases, but without significant prior experience in the diagnosis of anal cancer precursor lesions. The individual readings of each pathologist were compared to the one following the consensus diagnosis in shared optical microscope by kappa statistics. RESULTS: The absolute agreement between each individual diagnosis and corresponding consensus was poor (kappa = -0.002). Considering only the positive or negative results for anal squamous intraepithelial lesions, we obtained a fair agreement between observers (kappa = 0.35), while the agreement was moderate when the histopathological findings were considered positive or negative for high-grade squamous intraepithelial lesion or cancer (kappa = 0.52). CONCLUSION: The interobserver variability in histopathologic diagnosis of anal cancer and its precursor lesions among pathologists with little experience in the area is such that the diagnoses in this field and this scenario should always be a consensus.