Tratamiento digital de retinografías para detectar automáticamente lesiones asociadas con la retinopatía diabética / Retinal image analysis to detect lesions associated with diabetic retinopathy

Objetivos: La retinopatía diabética es la causa más frecuente de ceguera en la población activa de los países industrializados. Para retrasar su evolución y evitar así la pérdida de visión, el mejor método de prevención es un seguimiento regular médico. Para ello, se utilizan las imágenes de fondo de ojo o retinografías. Sin embargo, debido al gran número de pacientes, se requiere mucho esfuerzo y tiempo para revisar todas las imágenes. El objetivo de este trabajo es desarrollar un método automático que ayude a detectar los primeros síntomas de la retinopatía diabética mediante un tratamiento digital de las retinografías. Métodos: El método expuesto en este artículo se centra exclusivamente en la detección de exudados duros, uno de los primeros síntomas de la retinopatía diabética. Su localización automática se basa en su color, usando clasificación estadística, y sus bordes definidos, mediante un filtro detector de bordes. Resultados: Aplicando el algoritmo propuesto a 20 retinografías de distinta calidad, iluminación y color, obtuvimos una sensibilidad de 79,62% con una media de 3 falsos positivos por imagen. El número de falso negativos aumentaba sobre todo cuando los exudados aparecían muy cerca de los vasos sanguíneos. Conclusión: El objetivo final de este proyecto es automatizar el seguimiento médico de la retinopatía diabética mediante el tratamiento digital de las retinografias de los pacientes. En esta primera etapa, se ha desarrollado una herramienta que permite la detección automática de una lesión asociada a esta enfermedad: los exudados duros. En futuros trabajos se pretende mejorar los resultados obtenidos y continuar con la localización de otras lesiones(AU)

Purpose: Diabetic retinopathy is a leading cause of vision loss in developed countries. Regular diabetic retinal eye screenings are needed to detect early signs of retinopathy, so that appropriate treatments can be rendered to prevent blindness. Digital imaging is becoming available as a means of screening for diabetic retinopathy. However, with the large number of patients undergoing screenings, medical professionals require a tremendous amount of time and effort in order to analyse and diagnose the fundus photographs. Our aim is to develop an automatic algorithm using digital image analysis for detecting these early lesions from retinal images. Methods: An automatic method to detect hard exudates, a lesion associated with diabetic retinopathy, is proposed. The algorithm is based on their colour, using a statistical classification, and their sharp edges, applying an edge detector, to localise them. Results: A sensitivity of 79.62% with a mean number of 3 false positives per image is obtained in a database of 20 retinal images with variable colour, brightness and quality. It can also be seen that the number of the false negative cases increases when the hard exudates were very close to the vessel tree. Conclusion: The long term goal of the project is to automate the screening for diabetic retinopathy with retinal images. We have described the preliminary development of a tool to provide automatic analysis of digital fundus photographs to localise hard exudates. Future work will address the issue of improving the obtained results and also will focus on detecting other lesions(AU)

[Retinal image analysis to detect lesions associated with diabetic retinopathy]. / Tratamiento digital de retinografías para detectar automáticamente lesiones asociadas con la retinopatía diabética.

PURPOSE: Diabetic retinopathy is a leading cause of vision loss in developed countries. Regular diabetic retinal eye screenings are needed to detect early signs of retinopathy, so that appropriate treatments can be rendered to prevent blindness. Digital imaging is becoming available as a means of screening for diabetic retinopathy. However, with the large number of patients undergoing screenings, medical professionals require a tremendous amount of time and effort in order to analyse and diagnose the fundus photographs. Our aim is to develop an automatic algorithm using digital image analysis for detecting these early lesions from retinal images. METHODS: An automatic method to detect hard exudates, a lesion associated with diabetic retinopathy, is proposed. The algorithm is based on their colour, using a statistical classification, and their sharp edges, applying an edge detector, to localise them. RESULTS: A sensitivity of 79.62% with a mean number of 3 false positives per image is obtained in a database of 20 retinal images with variable colour, brightness and quality. It can also be seen that the number of the false negative cases increases when the hard exudates were very close to the vessel tree. CONCLUSION: The long term goal of the project is to automate the screening for diabetic retinopathy with retinal images. We have described the preliminary development of a tool to provide automatic analysis of digital fundus photographs to localise hard exudates. Future work will address the issue of improving the obtained results and also will focus on detecting other lesions.

Characterization of tryptophan high affinity transport system in pinealocytes of the rat. Day-night modulation.

Tryptophan is required in the pineal gland for the formation of serotonin, precursor of melatonin biosynthesis. The level of this amino acid in the serum and in the pineal gland of the rat undergoes a circadian rhythm, and reduced plasma tryptophan concentration decreases secretion of melatonin in humans. Tryptophan is transported into the cells by the long chain neutral amine acid system T and by the aromatic amino acid system T. The high affinity component of [(3)H]tryptophan uptake was studied in pinealocytes of the rat. Inhibition was observed in the presence of phenylalanine or tyrosine, but not in the presence of neutral amino acids, alanine, glycine, serine, lysine or by 2-aminobicyclo[2,2,1]-heptane-2-carboxylic acid, a substrate specific for system L. The transport of tryptophan was temperature-dependent and trans-stimulated by phenylalanine and tyrosine, but was energy-, sodium-, chloride-, and pH-independent. In addition, the sulphydryl agent N-ethylmaleimide did not modify the high affinity transport of tryptophan in pinealocytes. The kinetic parameters were not significantly different at 12:00 as compared to 24:00 h. The treatment with the inhibitor of tryptophan hydroxylase, p-chlorophenylalanine, produced an increase in the maximal velocity of the uptake and a reduction in the affinity at 12:00, but not at 24:00 h, probably indicating that during the day, the formation of serotonin in the pineal gland is favoured by elevating the uptake of tryptophan, whereas at 24:00 h other mechanisms, such as induction of enzymes are taking place. High affinity tryptophan uptake in the rat pineal gland occurs through system T and is upregulated during the day when the availability of serotonin is reduced.

[Migraine and MIDAS (MIDASELA) in Colombian hospital workers]. / Migraña y MIDAS (MIDASELA) en trabajadores hospitalarios colombianos.

AIMS: The aim of this study was to determine the prevalence of migraine and its implications in the occupational and outside employment/daily activities of the workers at a regional hospital in the Cundiboyacense Plateau in Colombia. PATIENTS AND METHODS: The available members of the house staff at this institution were interviewed by applying the neuroepidemiological protocol drawn up by the World Health Organization (WHO); general doctors performed the initial screening and the determination of neurological disease was carried out by a clinical neurologist, both in patients who were positive and negative for neurological disease. Quality of life was evaluated by means of the MIDAS (Migraine Disability Assessment) survey, MIDASELA (in Spanish for Latin America); the analysis was performed using the EPI 6.04 software application. RESULTS: A total of 238 people were studied: 188 females and 50 males; the prevalence of migraine was 22.5% (15.5% by the WHO protocol and 7% false negatives), with predominance in females (OR: 5.49; p< 0.005). In the MIDASELA questionnaire, 47.2% of the patients had a 50% alteration in their productivity, with regard to their occupational and outside employment/daily activities. A minimum number of patients (3.8%) were unable to work because of migraine, as compared to the figures for outside employment/daily activities (29.7%) or those involving leisure/family (66.4%). The average work, outside employment/daily and family time lost per patient because of migraine was 0.3, 2 and 5.2 days, respectively. CONCLUSION: A sub register in the prevalence of migraine could be reported in places where the WHO protocol is used. This pathology will have to be taken well into account in Colombian hospital workers due to its individual, occupational, family, social and economic impact. It is necessary to introduce health policies and programmes aimed at evaluating, controlling and treating this type of pathology in an appropriate manner, in order to improve the quality of life of those whose job it is to look after and improve that of the other Colombians.

Role of bradykinins and nitric oxide in the AT2 receptor-mediated hypotension.

Footshocks increases mean arterial pressure and heart rate. Systemic or intracerebroventricular (IVT) administration of losartan, a specific angiotensin AT1 receptor antagonist, not only inhibited the pressor response to footshocks but resulted in vasodepression. Peripheral or IVT administration of PD 123319, a specific angiotensin AT2 receptor antagonist, did not alter the haemodynamic response to footshocks. However, simultaneous blockade of angiotensin AT1 and AT2 receptors by combined systemic or central administration of losartan and PD 12319, eliminated the vasodepressor response to footshocks unmasked in losartan pretreated rats. Our data suggest that activation of peripheral or brain angiotensin AT2 receptor mediated the vasodepressor response to footshocks in the presence of angiotensin AT1 receptor antagonist. We studied the role of kinins and nitric oxide in the vasodepressor response observed after footshocks. The decrease in mean arterial pressure observed after footshocks in losartan treated rats was blunted by systemic or IVT administration of icatibant (HOE 140) or N(G)-nitro-L-arginine-methyl ester, indicating that peripheral or brain kinins and nitric oxide are involved in the hypotensor response to footshocks during angiotensin AT1 receptor blockade. Our results suggest a role for angiotensin AT2 receptor in the regulation of arterial blood pressure, possibly through the release of vasodilator autacoids such as bradykinins and nitric oxide.