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The topography of platinum electrodes produced by electrodeposition (19 to 200 mC cm-2) on highly oriented pyrolytic graphite (HOPG) under different potential modulations was investigated by atomic force microscopy, scanning tunneling microscopy, and H-atom electrosorption voltammetry. To modulate electrodeposition, (i) triangular potential cycling at 0.1 V s-1, (ii) a linear cathodic potential at 0.1 V s-1 and anodic potential step cycling, and (iii) square wave potential cycling at 5000 Hz were utilized. AFM and STM imaging showed that at lower platinum loading the HOPG surface was partially covered by a 3D sublayer of platinum. Electrodes produced by procedure (i) were made of faceted platinum aggregates of about 200 nm and nanoclusters in the range of 5-20 nm; those that resulted from procedure (ii) consisted of anisotropic aggregates of nanoclusters arranged as quasi-parallel domains. These electrodes from (i) and (ii) behaved as fractal objects. The electrodes resulting from procedure (iii) exhibited a flat surface that behaved as a Euclidean object. For all WEs, as the platinum loading was increased the HOPG surface was fully covered by a thin 3D layer of platinum aggregates produced by electrodeposition and coalescence phenomena. Large platinum loading led to electrodes with fractal geometry. Statistical parameters (root-mean-square height, skewedness, kurtosis, anisotropy, Abbot curve, number of protrusions and valleys, and fractal dimension) were obtained from the analysis of AFM and STM imaging data. Platinum electrodeposition coupled to either H-adatom formation for procedures (i) and (ii) or phonon dispersion for (iii) was involved in the surface atom rearrangements related to electrofaceting. The H-adatom electrosorption voltammetry data were used to evaluate the real electrode surface area via the voltammetric charge and to advance a tentative explanation of the contribution of the different crystallographic facets to the global electrochemical process dominated by weak H-Pt adsorption interactions.

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Kinetics and mechanism of the oxidation of tyrosine (Tyr) and valine (Val) di- and tripeptides (Tyr-Val, Val-Tyr and Val-Tyr-Val) mediated by singlet molecular oxygen [O(2)((1)Delta(g))], phosphate (HPO(4)(*-) and PO(4)(*2-)) and sulfate (SO(4)(*-)) radicals was studied, employing time-resolved O(2)((1)Delta(g)) phosphorescence detection, polarographic determination of dissolved oxygen and flash photolysis. All the substrates were highly photooxidizable through a O(2)((1)Delta(g))-mediated mechanism. Calculated quotients between the overall and reactive rate constants for the quenching of O(2)((1)Delta(g)) by Tyr-derivatives (k(t)/k(r) values, accounting for the efficiency of the effective photooxidation) were 1.3 for Tyr, 1 for Tyr-Val, 2.8 for Val-Tyr and 1.5 for Val-Tyr-Val. The effect of pH on the kinetics of the photooxidative process confirms that the presence of the dissociated phenolate group of Tyr clearly dominates the O(2)((1)Delta(g)) quenching process. Products analysis by LC-MS indicates that the photooxidation of Tyr di- and tripeptides proceeds with the breakage of peptide bonds. The information obtained from the evolution of primary amino groups upon photosensitized irradiation is in concordance with these results. Absolute rate constants for the reactions of phosphate radicals (HPO(4)(*-) and PO(4)(*2-), generated by photolysis of the P(2)O(8)(4-) at different pH) and sulfate radicals (SO(4)(*-), produced by photolysis of the S(2)O(8)(2-)) with Tyr peptides indicate that for all the substrates, the observed tendency in the rate constants is: SO(4)(*-) > or = HPO(4)(*-) > or = PO(4)(*2-). Formation of the phenoxyl radical of tyrosine was detected as an intermediate involved in the oxidation of tyrosine by HPO(4)(*-).

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A close relationship between alcohol consumption and hypertension has been established, but it is unclear whether there is a threshold level for this association. In addition, it has infrequently been studied in longitudinal studies and in black people. In a cohort study, 8334 of the Atherosclerosis Risk in Communities (ARIC) Study participants, aged 45 to 64 years at baseline, who were free of hypertension and coronary heart disease had their blood pressures ascertained after 6 years of follow-up. Alcohol consumption was assessed by dietary interview. The type of alcoholic beverage predominantly consumed was defined by the source of the largest amount of ethanol consumed. Incident hypertension was defined as a systolic blood pressure >/=140 mm Hg or diastolic blood pressure >/=90 mm Hg or use of antihypertensive medication. There was an increased risk of hypertension in those who consumed large amounts of ethanol (>/=210 g per week) compared with those who did not consume alcohol over the 6 years of follow-up. The adjusted odds ratios (95% confidence interval) were 1.2 (0.85 to 1.67) for white men, 2.02 (1.08 to 3.79) for white women, and 2.31 (1.11 to 4.86) for black men. Only 4 black women reported drinking >210 g ethanol per week. At low to moderate levels of alcohol consumption (1 to 209 g per week), the adjusted odds ratios (95% confidence interval) were 0.88 (0.71 to 1.08) in white men, 0.89 (0.73 to 1.09) in white women, 1.71 (1.11 to 2.64) in black men, and 0.88 (0.59 to 1.33) in black women. Systolic and diastolic blood pressures were higher in black men who consumed low to moderate amounts of alcohol compared with the nonconsumers but not in the 3 other race-gender strata. Models with polynomial terms of alcohol exposure suggested a nonlinear association in white and black men. Higher levels of consumption of all types of alcoholic beverages were associated with a higher risk of hypertension for all race-gender strata. The consumption of alcohol in amounts >/=210 g per week is an independent risk factor for hypertension in free-living North American populations. The consumption of low to moderate amounts of alcohol also appears to be associated with a higher risk of hypertension in black men.

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Blood pressure (BP) has a seasonal cycle in the general population and in patients undergoing maintenance dialysis, but the causes remain unclear. We studied the BP measurements recorded at fixed hours three times weekly from 1994 to 1997 in 102 hemodialysis patients. We obtained monthly averages of the following variables: predialysis mean BP, greatest overhydration (OH) estimated by predialysis body weight excess over dry weight, chronic OH estimated by the remaining postdialysis weight excess over dry weight, urea reduction ratio (URR) in dialysis, and monthly means for daylight span and outdoor temperature over the study period. Average BP in the population diminished over the 48-month period, associated with a decrease in chronic OH (r = 0.66; P < 0.0005) but independent of greatest OH. BP and chronic OH presented synchronous seasonal variations, with peaks in late autumn and early winter and troughs in summer. These biological rhythms were inversely related to the seasonal daylight span and outdoor temperature. Both BP and chronic OH periods were synchronous with the daylight annual cycle and preceded the seasonal variations of temperature by 1 month. Multiple regression analysis showed that chronic OH and daylight, but not URR or temperature, had a significant independent association with BP changes. These results show the existence of seasonal variations of BP in dialysis patients that are associated and synchronous with seasonal changes in chronic OH status. Both cycles depend on conditions influenced by the annual daylight span more than by external temperature.

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The Caribbean nation of Cuba is comprised of over 10 million persons who trace their ancestry primarily to Africa and Spain. To date, little data on blood pressure (BP) or hypertension prevalence from Cuba have appeared in English language journals. Because the current government has pursued an active policy of reducing social differentiation on the basis of ethnic origin, Cuba provides an important population laboratory from which to advance the understanding of black-white differences in BP and hypertension. The authors conducted a population-based random sample among adults (aged > 15 years) in the city of Cienfuegos. Overall response rate was 95%, yielding 1633 participants who provided BP readings, self-reported racial group, demographic information, and treatment status. Overall prevalence of hypertension (SBP > or = 140 mm Hg or DBP > or = 90 mm Hg or currently treated) was 44% (46% among blacks and 43% whites; P = 0.19). Excess BP among black subjects was reduced slightly by excluding those under treatment, but attained statistical significance after adjustment for sex and age (P = 0.01). The black-white difference was small, however, relative to that observed in the United States. Racial differences in treatment status and control were also observed. Although there remains a difference in socioeconomic profile between those of African and of European origin in Cuba, this has decreased over recent decades. In the United States, the greater magnitude of social differentiation parallels a greater relative risk of BP elevation among blacks, suggesting that social, economic and psychological factors may play an important role in the observed racial gap in cardiovascular risk.

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The 1991 to 1994 epidemic of neuropathy in Cuba has been one of the more devastating in recent history, affecting more than 50,000 people throughout the entire country with clinical manifestations of optic and peripheral neuropathy. Although the causes are not entirely clear, it seems that a combination of acute nutritional deficiency and the toxic effects of tobacco and possibly other unidentified toxic substances is involved. The epidemic coincided with the acute worsening of the economic situation on the island following political changes in Eastern European countries and a tightening of the US economic embargo. This paper reviews reports of a strikingly similar epidemic known as the "Amblyopia of the Blockade," which occurred in Cuba almost a century ago when the island was undergoing a US naval blockade during the Cuban-Spanish-American war. It discusses the parallelism with the recent epidemic as well as the implications of this historical evidence to clarify further the ultimate causes of these epidemics.

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In English, odds ratio is a basic epidemiological measure approximating the relative risk. Odds ratio has been translated into Spanish in several ways, which has produced great terminological confusion. On the other hand, the English word odds is often used in epidemiology or statistics English textbooks, alone or as part of other expressions, but always keeping a definite mathematical meaning, which calls for a similarly definite term in Spanish. We discuss several translations of odds ratio found in the literature and propose the Spanish word "posibilidades" as a translation of odds and "razón de posibilidades" as a translation of odds ratio.

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