The Potential Use of Near Infrared Spectroscopy (NIRS) to Determine the Heavy Metals and the Percentage of Blends in Tea.

The following study analyzed the potential of Near Infrared Spectroscopy (NIRS) to predict the metal composition (Al, Pb, As, Hg and Cu) of tea and for establishing discriminant models for pure teas (green, red, and black) and their different blends. A total of 322 samples of pure black, red, and green teas and binary blends were analyzed. The results showed that pure red teas had the highest content of As and Pb, green teas were the only ones containing Hg, and black teas showed higher levels of Cu. NIRS allowed to predict the content of Al, Pb, As, Hg, and Cu with ratio performance deviation values > 3 for all of them. Additionally, it was possible to discriminate pure samples from their respective blends with an accuracy of 98.3% in calibration and 92.3% in validation. However, when the samples were discriminated according to the percentage of blending (>95%, 95-85%, 85-75%, or 75-50% of pure tea) 100% of the samples of 10 out of 12 groups were correctly classified in calibration, but only the groups with a level of pure tea of >95% showed 100% of the samples as being correctly classified as to validation.

[Relation between changes in retinal microcirculation and other organ damage in hypertension and regression with antihypertensive treatment]. / Relación entre los cambios en la microcirculación retiniana y la lesión de otros órganos diana en pacientes hipertensos y su regresión tras el tratamiento.

BACKGROUND AND OBJECTIVE: The possibility to aplicate a semi-automatic computerized system to evaluate the calibre of retinal blood vessels, has shown very good reproducibility, and have let us measure the calibres of retinal arterioles and veins, and their ratio (AVR). PATIENTS AND METHOD: We have measured the calibres of retinal vessels in a group of 51 hypertensive outpatients before and after 6 months' treatment with losartan or, losartan plus hydrochlorothiazide if the association was required to adequate control of the blood pressure. RESULTS: AVR increased from 0.7530 (0.03) to 0.7563 (0.03) (p = 0.005). We have related these modifications with damage in other target organs and we have found out a inverse relation between AVR and left ventricular mass index. This relation could be confirmed in multiple regression analysis. We have found no relation between AVR and microalbuminuria, probably because of its variability. CONCLUSIONS: These results suggest a relation between retinal microcirculation and hypertensive cardiopathy, but they should be interpreted with caution because the sample is small.

Relación entre los cambios en la microcirculación retiniana y la lesión de otros órganos diana en pacientes hipertensos y su regresión tras el tratamiento / Relation between changes in retinal microcirculation and other organ damage in hypertension and regression with antihypertensive treatment

Fundamento y objetivo: Aunque la evaluación de los cambios iniciales en la microcirculación retiniana es subjetiva y difícilmente reproducible, la posibilidad de disponer de un método semiautomático y reproducible permite cuantificar los cambios iniciales y su modificación con el tratamiento antihipertensivo. Pacientes y método: Hemos cuantificado los cambios en la microcirculación retiniana, medidos con el índice arteriovenoso retiniano, en un grupo de 51 hipertensos, y hemos observado su modificación tras 6 meses de tratamiento antihipertensivo con losartán combinado o no con hidroclorotiazida. Resultados: El índice arteriovenoso (IAV) retiniano aumentó de 0,7530 (0,03) a 0,7563 (0,03) (p = 0,005). Hemos relacionado estas modificaciones con los cambios en la lesión de otros órganos diana, y encontramos una relación inversa entre los cambios en la microcirculación y el índice de masa ventricular izquierda. Dicha relación se confirmó en el análisis multivariable. No se encontró relación entre el IAV y la microalbuminuria, probablemente por la amplia dispersión de sus valores. Conclusiones: Los resultados indican una relación entre microcirculación retiniana y cardiopatía hipertensiva, aunque se debe interpretar con cautela, al tratarse de una muestra pequeña

Background and objective: The possibility to aplicate a semi-automatic computerized system to evaluate the calibre of retinal blood vessels, has shown very good reproducibility, and have let us measure the calibres of retinal arterioles and veins, and their ratio (AVR). Patients and method: We have measured the calibres of retinal vessels in a group of 51 hypertensive outpatients before and after 6 months' treatment with losartan or, losartan plus hydrochlorothiazide if the association was requiered to adequate control of the blood pressure. Results: AVR increased from 0.7530 (0.03) to 0.7563 (0.03) (p = 0.005). We have related these modifications with damage in other target organs and we have found out a inverse relation between AVR and left ventricular mass index. This relation could be confirmed in multiple regression analysis. We have found no relation between AVR and microalbuminuria, probably because of its variability. Conclusions: These results suggest a relation between retinal microcirculation and hypertensive cardiopathy, but they should be interpreted with caution because the sample is small

Regression of alterations in retinal microcirculation following treatment for arterial hypertension.

Evaluation of early hypertension-related alterations in retinal microcirculation has been subjective and poorly reproducible. The authors recently described a semiautomatic computerized system for evaluation of the calibre of retinal blood vessels that has shown very good reproducibility. In the study, this system was used to measure the calibres of retinal arterioles and veins, and their ratio, in a group of 51 hypertensive outpatients before and after 6 months of treatment with losartan or, if required for satisfactory blood pressure control, losartan plus hydrochlorothiazide. Mean retinal arteriole diameter increased from 0.0842 +/- 0.003 mm to 0.0847 +/- 0.003 mm (p = 0.001). Arteriovenous ratio increased from 0.753 +/- 0.03 to 0.756 +/- 0.03 (p = 0.005). This observation suggests regression of early hypertension-related alterations in retinal microcirculation after 6 months of antihypertensive treatment.

Computerized measurement of retinal blood vessel calibre: description, validation and use to determine the influence of ageing and hypertension.

OBJECTIVE: To validate a computer-based method for measuring the calibre of retinal blood vessels, and use it to determine the effects of ageing and arterial hypertension on the calibres of these vessels and on their ratio. METHODS: Digital eye fundus images covering a 50 degrees field and centred on the optic disc were obtained using a 540 nm filter. The boundaries of blood vessels crossing a series of circles concentric with the optic disc were located by an image analysis program; the calibres of vessels crossing the circles perpendicularly were determined automatically, the average arteriole and average vein calibres were calculated, and the arteriovenous ratio (AVR) was calculated as the ratio of these averages. The within-operator, between-operator and within-eye reliability of this method was investigated using images of 30 or 40 eyes; the effects of ageing on average vessel calibres and AVR using both eyes of each of 120 normotensive volunteers aged 10-69 years (60 males, 60 females); and the effects of arterial hypertension using a group of 54 hypertensive patients aged 50.9 +/- 13.9 years. RESULTS: Within-operator, between-operator and within-eye correlation coefficients for AVR were all better than 0.95, and the corresponding coefficients of variation were all better than 3%. The results of Bland Altman approach show a very good agreement. There were no significant differences between right and left eyes or between the sexes in either the normotensive or the hypertensive group. In the normotensive group, vein calibre was almost constant (111 +/- 6 microm), but arteriole calibre and AVR fell significantly from 96 +/- 6 microm and 0.870 +/- 0.046, respectively, in the second decade of life to 85 +/- 4 microm and 0.761 +/- 0.044 in the seventh decade. Arterial hypertension was not associated with changes in vein calibre, but was associated with decreases in arteriole calibre (from 91 +/- 7 microm among normotensive individuals to 84 +/- 2 microm) and AVR (from 0.816 +/- 0.056 to 0.755 +/- 0.027). Age significantly modulated the AVR-reducing influence of hypertension (P = 0.003). CONCLUSION: The proposed method of measuring retinal blood vessel calibres is reliable and precise (especially for the AVR). In this study, its results confirmed that increasing age and arterial hypertension are both associated with reductions in retinal arteriole calibre and AVR.