Contaminación por mercurio en humanos y peces en el Municipio de Ayapel, Córdoba, Colombia, 2009 / Mercury contamination in humans and fishes in the municipality of Ayapel, Córdoba, Colombia, 2009

Objetivo: evaluar las concentraciones de mercurio total (Hg-T) en cabello de habitantes del municipio de Ayapel (Córdoba) y en peces capturados en la ciénaga de Ayapel. Metodología: se tomaron 112 muestras de cabello de la región occipital in¬ferior a pobladores ribereños de la ciénaga de Ayapel mayores de 14 años y muestras de tejido muscular a siete especies de peces; estas fueron analizadas por espectrometría de absorción atómica por vapor frío después de digestión ácida. Se aplicaron encuestas sobre síntomas clínicos relacionados con intoxica¬ción por mercurio, previa aceptación del consentimiento infor¬mado. Resultados: los resultados de mercurio total en cabello presentaron una media de 2,18 ± 1,77 μg/g con valores entre 0,11 y 12,76 μg/g. El valor mas alto de Hg-T en peces lo pre¬sentó la especie carnívora Sorubin cuspicaudus, con concen¬tración media de 0,74 ± 0,19 μg/g de peso fresco, y la menor concentración, la especie iliófaga Prochilodus magdalenae, con 0,15 ± 0,02 μg/g de peso fresco. Conclusiones: la pobla¬ción estudiada de Ayapel presentó concentraciones de mercu¬rio superiores a las permitidas internacionalmente por la Agen-cia de Protección Ambiental de los Estados Unidos (usepa) y síntomas acordes con tales niveles, lo que presumiblemente se debe al alto consumo de pescado contaminado con mercurio.

Objective: to assess the concentration of total mercury (Hg-T) in hair samples from inhabitants of the municipality of Ayapel (Córdoba) and in fishes captured in the Ayapel swamp. Methodology: a total amount of 112 hair samples were taken from the inferior occipital area of settlers of the Ayapel swamp who were over 14 years old, and samples of muscle tissue of seven species of fishes were also chosen. These samples were analyzed by means of spectrometry of atomic absorption through cold steam after acid digestion. Surveys on clinical symptoms related to poisoning by mercury were applied after the acceptance of the informed consent. Results: the total amount of mercury present in hair displayed an average of 2.18 ± 1.77 μg/g with values between 0.11 and 12.76 μg/g. The highest value of Hg-T in fishes was identified in the carnivorous species Sorubin cuspicaudus, with an average concentration of 0.74 ± 0,19 μg/g, and the smaller concentration was found on the iliophagous species Prochilodus magdalenae with 0.15±0.02 μg/g of fresh weight. Conclusions: the population studied in Ayapel showed mercury levels above those internationally allowed by the usepa. There were also signs and symptoms related to such mercury levels, which can probably be a consequence of the high consumption of fishes contaminated with mercury.

Characterization of dilute species within CVD-grown silicon nanowires doped using trimethylboron: protected lift-out specimen preparation for atom probe tomography.

Three-dimensional quantitative compositional analysis of nanowires is a challenge for standard techniques such as secondary ion mass spectrometry because of specimen size and geometry considerations; however, it is precisely the size and geometry of nanowires that makes them attractive candidates for analysis via atom probe tomography. The resulting boron composition of various trimethylboron vapour-liquid-solid grown silicon nanowires were measured both with time-of-flight secondary ion mass spectrometry and pulsed-laser atom probe tomography. Both characterization techniques yielded similar results for relative composition. Specialized specimen preparation for pulsed-laser atom probe tomography was utilized and is described in detail whereby individual silicon nanowires are first protected, then lifted out, trimmed, and finally wet etched to remove the protective layer for subsequent three-dimensional analysis.

Secondary focal segmental glomerulosclerosis in non-obese patients with increased muscle mass.

BACKGROUND: Secondary focal segmental glomerulosclerosis (FSGS) is a pattern of glomerular injury mediated by hyperfiltration and other adaptive structural-functional responses. We describe 3 non-obese patients with elevated body mass index (BMI) owing to increased muscle mass who had renal biopsy findings favoring a form of secondary FSGS. METHODS: Clinical and pathologic data were obtained on 3 patients with 1) renal biopsy findings of focal segmental and/or global glomerulosclerosis with glomerulomegaly; 2) BMI > or = 30; 3) body fat percentage < 20%; 4) "highly muscular" appearance, and 5) proteinuria > or = 1 g/d without nephrotic syndrome. 24-hour urine creatinine excretion was used to estimate lean body mass and percentage body fat. RESULTS: The 3 patients were males (age 38 - 48 years) employed in jobs requiring strenuous physical activity. BMIs ranged from 30.4 - 32.1 kg/m2 with body fat percentages of 12.9 - 16.8%. Creatinine clearances at time of biopsy ranged from 113 - 208 ml/min. Renal biopsies showed focal segmental and/or global glomerulosclerosis affecting a minority of glomeruli with glomerular hypertrophy and minimal (mean 15%) foot process effacement. Treatments included angiotensin-converting enzyme inhibitor, angiotensin II receptor blocker, or weight loss. Over a mean follow-up time of 24.3 months, serum creatinine remained stable and proteinuria decreased in all patients. CONCLUSIONS: Non-obese patients with increased BMI due to elevated muscle mass are at risk of developing a secondary form of FSGS that resembles obesity-related glomerulopathy.

Vacuum electron acceleration by coherent dipole radiation.

The validity of the concept of laser-driven vacuum acceleration has been questioned, based on an extrapolation of the well-known Lawson-Woodward theorem, which stipulates that plane electromagnetic waves cannot accelerate charged particles in vacuum. To formally demonstrate that electrons can indeed be accelerated in vacuum by focusing or diffracting electromagnetic waves, the interaction between a point charge and coherent dipole radiation is studied in detail. The corresponding four-potential exactly satisfies both Maxwell's equations and the Lorentz gauge condition everywhere, and is analytically tractable. It is found that in the far-field region, where the field distribution closely approximates that of a plane wave, we recover the Lawson-Woodward result, while net acceleration is obtained in the near-field region. The scaling of the energy gain with wave-front curvature and wave amplitude is studied systematically.

Lithium-induced renal disease: a prospective study.

Considerable controversy exists as to whether lithium maintenance therapy is associated with the development of renal insufficiency. In 1980 we initiated a prospective study of renal function in manic-depressive patients beginning lithium therapy. None of the patients had evidence of pre-existing renal disease. Sixty-five patients were entered, and 51 and 18 patients completed 1 and 3 years of follow-up, respectively. Lithium doses were titrated to the lowest level consistent with control of psychiatric symptoms; there were no episodes of overt lithium intoxication. Serum creatinine levels in all patients, and endogenous creatinine clearance in women, remained stable over the course of the study. In contrast, creatinine clearances (mean +/- SEM, ml/min/1.73 m2) in men significantly decreased over both 1 year (110 +/- 4 to 95 +/- 5, n = 21, p = 0.0126) and 3 years (107 +/- 4 to 80 +/- 11, n = 8, p = 0.0385) of evaluation. Although all patients demonstrated a mild reduction in renal concentrating ability after initiation of lithium, the decrease was not progressive over the course of the study. Quantitative urinary protein excretion did not change, and repeated urinalyses did not reveal any evidence of renal disease. Thus, lithium therapy appears to result in modestly reduced rates of glomerular filtration, as measured by endogenous creatinine clearance, in men receiving lithium maintenance therapy for manic-depressive illness. Whether this reduction is progressive and leads to clinically significant renal insufficiency requires further investigation.

Hemodynamic consequences of continuous arteriovenous hemofiltration.

Continuous arteriovenous hemofiltration (CAVH) is an extracorporeal treatment in which fluid, electrolytes, and low and middle molecular weight solutes are removed from the blood by ultrafiltration. It is efficacious in the management of acute or chronic renal failure complicated by fluid overload, and following surgery. In this study, cardiac filling pressures, cardiac indices, and BP were monitored in nine patients. A mean of 7 kg of fluid was removed in ten treatments without the induction of hypotension. In nine of ten treatments, cardiac index increased following fluid removal. An increment in myocardial pump function was noted even in patients with low output heart failure. This treatment differs from dialysis in its ability to remove large fluid volumes without compromising cardiac hemodynamics. In addition, CAVH may have a role in treating volume overload patients with renal insufficiency and heart failure resistant to pharmacologic intervention.

Effects of guanabenz on sodium and water homeostasis.

Sodium retention may partially offset the therapeutic action of some antihypertensive agents. To assess the effects of guanabenz on sodium balance, six men with mild to moderate hypertension were placed on diets with constant sodium intake (120 mEq/day) for approximately 4 weeks. After achieving sodium balance, the subjects received guanabenz (16-24 mg daily) for approximately 2 weeks. Mean supine blood pressure decreased from 144/93 to 133/86 mmHg during guanabenz treatment (p less than 0.001). Guanabenz therapy was associated with a decrease in body weight (mean +/- SE) from 85.4 +/- 7.0 to 84.4 +/- 6.8 kg (p less than 0.01). Sodium balance, glomerular filtration rate, plasma renin activity, mean maximal urine osmolality, fluid intake, urine volume, and serum sodium concentration were unchanged during guanabenz therapy. Three additional balance studies were performed during a period of greater sodium intake (180 mEq/day). Although higher doses of guanabenz were required to achieve blood pressure control, sodium balance still was not affected by the drug. Thus, an effective therapeutic dose of guanabenz administered for 2 weeks had no clinically significant effects on sodium or water homeostasis in patients with mild to moderate hypertension.

Steroid-induced protein synthesis in giant-toad (Bufo marinus) urinary bladders. Correlation with natriferic activity.

We have identified a group of proteins (Mr approximately 70 000-80 000; pI approximately 5.5-6.0) in giant-toad (Bufo marinus) urinary bladders whose synthesis appears to be related to aldosterone-stimulated Na+ transport. Spironolactone, a specific mineralocorticoid antagonist in renal epithelia, inhibits the synthesis of these proteins as well as the natriferic effect of the hormone. Since a variety of other steroids (some of which are traditionally considered to be glucocorticoids) also stimulate Na+ transport in toad urinary bladders, we examined whether their natriferic activity was expressed in a fashion similar to that of aldosterone. Short-circuit current was used to measure Na+ transport, and epithelial-cell protein synthesis was detected with high-resolution two-dimensional polyacrylamide-gel electrophoresis and autoradiography. At a concentration of approximately 100 nM, dexamethasone, corticosterone and aldosterone were equinatriferic. Dexamethasone and aldosterone had identical dose-response curves, maximal and half-maximal activity being evident at concentrations of approximately 100 nM and 10 nM respectively. In contrast, at a concentration of approximately 10 nM, corticosterone had no effect on Na+ transport. The natriferic activities of these three steroids correlate with their known affinities for the putative mineralocorticoid receptor in toad urinary bladders. Natriferic concentrations of dexamethasone and corticosterone (140 nM) induced the synthesis of proteins with characteristics identical with those induced by aldosterone. Spironolactone, at an antagonist/agonist ratio of 2000:1, inhibited steroid-induced Na+ transport and the synthesis of these proteins. Thus it appears that all natriferic steroids share a common mechanism of action in toad urinary bladders. Natriferic activity can be correlated not only with relative steroid-receptor affinity but also with the induction of a specific group of epithelial-cell proteins.

Mineralocorticoid-specificity of aldosterone-induced protein synthesis in giant-toad (Bufo marinus) urinary bladders.

We have identified a group of proteins (Mr approximately 70000-80000; pI approximately 5.8-6.4) in giant-toad (Bufo marinus) urinary-bladder epithelial cells whose synthesis appears to be related to aldosterone-stimulated Na+ transport. To define this relationship further, we examined whether submaximal natriferic concentrations of aldosterone induced these proteins and whether spironolactone (a specific mineralocorticoid antagonist in renal epithelia) inhibited their synthesis. Short-circuit current was used to measure Na+ transport and epithelial-cell protein synthesis was detected with high-resolution two-dimensional polyacrylamide-gel electrophoresis and autoradiography. Submaximal natriferic concentrations of aldosterone (1.4 X 10(-8) M) induced the same proteins as maximal concentrations of the hormone (1.4 X 10(-7) M). In contrast, in previous experiments, similar proteins were not induced by subnatriferic concentrations (5.0 X 10(-8) M) of cortisol, a glucocorticoid. A spironolactone/aldosterone molar ratio of 2000:1 was required to inhibit aldosterone-stimulated Na+ transport completely; ratios of 200:1 and 500:1 produced partial inhibition. Concentrations of spironolactone that abolished aldosterone-stimulated Na+ transport also inhibited aldosterone-induced protein synthesis. We conclude that the synthesis of the proteins we have identified is specifically related to activation of the mineralocorticoid pathway.