Nonlocal finite difference discretization of a class of renewal equation models for epidemics.

In this paper we consider a non-standard discretization to a Volterra integro-differential system which includes a number of age-of-infection models in the literature. The aim is to provide a general framework to analyze the proposed scheme for the numerical solution of a class of problems whose continuous dynamic is well known in the literature and allow a deeper analysis in cases where the theory lacks.

Optical Coherence Tomography Angiography in Central Retinal Vein Occlusion: Macular Changes and Their Correlation with Peripheral Nonperfusion at Ultra-Widefield Fluorescein Angiography.

INTRODUCTION: The aim of this study was to investigate the correlation between ischemic index (ISI) measured on ultra-widefield (UWF) fluorescein angiography (FA) images and macular parameters obtained by optical coherence tomography angiography (OCT-A) in eyes affected by central retinal vein occlusion (CRVO). METHODS: Retrospective study of data from 12 eyes affected by treatment-naïve CRVO. All patients underwent a comprehensive ocular examination including structural OCT, OCT-A, and UWF FA. Variables analyzed included best corrected visual acuity (BCVA) measured with the ETDRS chart; foveal avascular zone (FAZ) area at full-thickness OCT-A angiogram; perfusion density (PD) in the superficial (SCP) and deep capillary plexus (DCP); ISI; and central macular thickness (CMT). RESULTS: ISI showed a significant positive correlation with FAZ area (r = 0.63, p = 0.019) and a significant negative correlation with PD in the SCP (r = -0.62, p = 0.022), PD in the DCP (r = -0.66, p = 0.011), and BCVA (r = -0.75, p = 0.002). FAZ area also negatively correlated to PD in the SCP (r = -0.75, p = 0.002) and DCP (r = -0.64, p = 0.016). BCVA positively correlated to PD in the SCP (r = 0.67, p = 0.009) and DCP (r = 0.68, p = 0.008), while a negative correlation was found with FAZ area (r = -0.65, p = 0.013) and CMT (r = -0.70, p = 0.006). DISCUSSION/CONCLUSION: OCT-A macular parameters (namely, FAZ area and PD of SCP and DCP) significantly correlated with ISI, a quantitative way to assess peripheral retinal nonperfusion on UWF FA. Macular OCT-A analysis may help in assessing the need for additional UWF FA testing in eyes affected by CRVO.

PHOTORECEPTOR OUTER SEGMENT IS EXPANDED IN THE FELLOW EYE OF PATIENTS WITH UNILATERAL CENTRAL SEROUS CHORIORETINOPATHY.

PURPOSE: To quantitatively evaluate the photoreceptor structural changes in the fellow unaffected eyes of patients with unilateral central serous chorioretinopathy (CSC). METHODS: This is a retrospective cross-sectional study. We analyzed data from patients with diagnosis of unilateral CSC, as based on clinical examination and multimodal imaging, who had structural optical coherence tomography obtained. An additional group of age-matched healthy patients was included for comparison. Main outcome measures were as follows: (1) the foveal photoreceptor outer segment lateral surface and (2) the foveal choroidal thickness. RESULTS: One hundred and sixty fellow unaffected eyes of 160 unilateral CSC patients and 50 age-matched controls (50 eyes) were included. The mean ± SD age was 51.6 ± 11.1 years (range 28-80 years) in the unilateral CSC group and 52.8 ± 10.8 years (range 31-74 years) in the control group (P = 0.511). The foveal photoreceptor outer segment lateral surface was significantly increased in the unaffected eyes with CSC in the fellow eye (0.068 ± 0.007 mm2) as compared with control eyes (0.060 ± 0.005 mm2, P < 0.0001). The mean ± SD foveal choroidal thickness was 368.0 ± 105.7 µm in the unilateral CSC group and 302.9 ± 92.2 µm in control patients (P < 0.0001). In the Pearson correlation test, the photoreceptor outer segment lateral surface correlated with the choroidal thickness in the CSC group (R = 0.166, P = 0.016) but not in the control group (R = -0.025, P = 0.864). CONCLUSION: Our results corroborate the hypothesis that retinal and choroidal changes affect both eyes of patients with acute/history of unilateral disease. These structural changes could be intended as an imaging evidence of reduced photoreceptor outer segment turnover secondary to retinal pigment epithelium and choroid dysfunction.

Effects of social exclusion and maternal rejection on Children's high-caloric food consumption.

Research has shown that the quality of interpersonal relationships plays an important role in influencing childhood obesity-risk behavior. However, studies conducted so far have focused mostly on self-report data. But they rarely control for the effect of experimentally-induced social rejection or perceived maternal rejection. The aim of this study was to investigate the effects of the quality of the maternal relationships as well as experimentally-induced social rejection on children's motivation to consume high-caloric food. Eighty children (8-12 years of age) and their mothers participated in an experimental study. Participants were randomly assigned to a social inclusion (acceptance) or exclusion (rejection) condition in a computer-based ball-toss game (Cyberball). After completing the Cyberball game, children were presented with high-caloric food and were evaluated on the amount of the food they consumed. Participants also completed a self-report questionnaire assessing their perceptions of their mothers' acceptance-rejection. Further, mothers' Body Mass Index (BMI) was measured, and a semi-structured interview was conducted to assess the tendency of mothers to regulate their child's stress with food. Results showed that the consumption of high-caloric food was directly influenced by the children's perceptions of maternal acceptance-rejection, and by the experience of brief, experimentally-induced social exclusion (rejection). Additionally, children's consumption of high-caloric food was related to their mothers' use of food to help regulate children's distress, and by the children's own BMI. The results document the importance of affective-relational experiences in the development of childhood obesity. The results also highlight the apparent fact that regardless of individual and family characteristics, the experience of even short-term social rejection can activate obesity-risk behaviors which deplete children's self-regulatory mechanisms, thereby resulting in more consumption of high-caloric food.

Correlación del ADN y del antígeno de superficie del virus de hepatitis B en tejidos de animales transgénicos

Se estudió la presencia del ácido desoxirribonucleico (ADN) que codifica para el antígeno de superficie del virus de hepatitis B (AgsHB) en los tejidos de ratones híbridos de transgénicos/BALB-c donde se había expresado el fenotipo previamente. Los órganos extraídos se evaluaron por la técnica de inmunohistoquímica, por un ELISA cuantitativo y reacción en cadena de la polimerasa (RCP) para la detección del ADN viral. En los tejidos estudiados se encontró ADN viral, excepto en el intestino donde no se evidenció su presencia en ninguno de los especímenes. Con la técnica de inmunohistoquímica no se logró detectar expresión de la proteína viral en intestino, músculo y vesícula seminal, sólo muy baja expresión en cerebro. Mediante la técnica inmunoenzimática no se detectó AgsHB en músculo, intestino, cerebro y estómago. Al evaluar el suero de la totalidad de los animales por medio de la técnica inmunoenzimática y con la RPC, 100 % de los sueros fueron positivos.

A study was made on the presence of DNA coding for Hepatitis B surface antigen (HbsAg) in hybrid transgenic /Balb-c mice where the phenotype had not been expressed before. The extracted organs were evaluated by immunohistochemistry, by quantitative ELISA and polymerase chain reaction (PCR) for detecting viral DNA which was found in the studied tissues except for the intestines in which none of the species was evident. The immunohistochemical technique did not manage to detect the expression of viral protein in the intestines, muscles and seminal vesicle, only a very low expression of such protein in the brain. The immunoenzymatic technique did not detect HbsAG in muscles, intestines, brain or stomach. However, when evaluationg the sera of all the animals by immunoenzymatic technique and PCR, 10% pf tje sera were positive to viral DNA.

Método de inmunocomplejos específicos para detectar ADN del virus de hepatitis B en pacientes con antigenemias bajas

Se evaluó la influencia de las concentraciones de las partículas asociadas con el virus de hepatitis B desde el punto de vista inmunológico mediante la formación de inmunocomplejos específicos (ICE), se determinó el DNA antes y después de formado el inmunocomplejo. Se utilizaron 10 muestras serológicas de pacientes portadores crónicos con antigenemia baja (menos de 1 mg/mL), a las que se les realizó la técnica de reacción en cadena de la polimerasa (RCP) para detección del ADN viral. A cada muestra se le aplicó la técnica de ICE mediante un estándar de anticuerpos para su formación in vitro, se realizó una purificación con fenol cloroformo para ser procesado por RCP. La amplificación de las muestras con inmunocomplejos demostró que la técnica de ICE poseía capacidad de concentrar el antígeno y éste pudo ser detectado cuando no era posible determinar las concentraciones en una electroforesis de agarosa.

We evaluated the influence of the concentrations of particles associated with Hepatitis B virus from the immunologic viewpoint through the formation of specific antibody-antigen complexes, and also we determined DNA before and after the formation of the complexes. We used 10 serological samples of chronic carrier patients with low antigenemia(less than 1µg/mL) which were subjected to PCR for detecting viral DNA. The antibody-antigen complex technique was used in each sample through standard antibodies for the complex to be formed in vitro, then purification with phenol chrololform to be PCR-processed. The amplification of samples with the antibody-antigen complexes showed that this technique was able to concentrate antigens, so it could be detected when it was impossible to determine antigen concentrations in an agar electrophoresis.