RESUMEN
Various studies have suggested that potassium depletion leads to acidosis and hypocitraturia. In Northeastern Thailand, for example, mild hypokalemia and mild hyperoxaluria are observed in most stone formers. However, there are limited reports about the direct link between potassium depletion and the formation of urinary stones, most of which are calcium oxalate stones. Therefore, we studied the direct effect of potassium depletion on the risk factors for calcium oxalate stone formation. Seventy-two rats were fed a control diet or a potassium-deficient diet for 1, 2, or 3 weeks (n = 12 per group). Twenty-four-hour urine collection was done for the measurement of potassium, calcium, oxalate, glycolate, citrate, phosphorus, and magnesium. Lactate dehydrogenase activity was also measured in order to assess renal tubular damage, and kidneys were harvested for histological examination. Furthermore, urinary supersaturation of calcium oxalate was calculated. With potassium depletion, the urinary concentrations of potassium, citrate, magnesium, and phosphorus decreased rapidly. There was no detectable renal damage, renal calcium deposition, and no significant increase of urinary oxalate or calcium. However, the urinary supersaturation index of calcium oxalate increased significantly in rats with potassium depletion. These findings indicate that potassium deficiency may increase the risk of stone formation through enhanced supersaturation.
Asunto(s)
Deficiencia de Potasio/complicaciones , Cálculos Urinarios/epidemiología , Urolitiasis/epidemiología , Animales , Oxalato de Calcio/orina , Citratos/orina , Modelos Animales de Enfermedad , Concentración de Iones de Hidrógeno , Magnesio/orina , Masculino , Potasio/orina , Deficiencia de Potasio/orina , Ratas , Ratas Wistar , Factores de Riesgo , Cálculos Urinarios/orina , Urolitiasis/orinaRESUMEN
We studied the effects of an intravenous hydroxypyruvate load on endogenous oxalogenesis in rats receiving a standard diet or a vitamin-B6-deficient diet. Twelve male Wistar rats were randomized to two groups and were fed either a standard diet or a vitamin-B6-deficient diet for 3 weeks. Then the animals received an intravenous infusion of 100 mg/ml (960.6 micromol/ml) of hydroxypyruvate slowly over 10 min. Urine samples were collected just before hydroxypyruvate infusion and at hourly intervals until 5 h afterward. Urinary oxalate, glycolate, and citrate levels were measured by capillary electrophoresis. Hourly urinary oxalate excretion peaked within 2 h, while urinary glycolate excretion peaked at 1 h, after the hydroxypyruvate load in both control and vitamin-B6-deficient rats. Both urinary oxalate and glycolate excretion were higher in vitamin-B6-deficient rats than in control rats. Infusion of hydroxypyruvate increased the 5-h urinary oxalate and glycolate excretion to 0.68% (6.56 micromol) and 0.53% (5.10 micromol) of the administered dose (mol/mol), respectively, in the control rats, while oxalate and glycolate excretion, respectively, increased to 2.43% (23.36 micromol) and 0.79% (7.59 micromol) of the dose in the vitamin-B6-deficient rats. Urinary citrate excretion was significantly lower at baseline and all other times in the vitamin-B6-deficient rats than in the control rats. In conclusion, a hydroxypyruvate load increased endogenous oxalate synthesis in control rats, and its synthesis was even greater in vitamin-B6-deficient rats. Vitamin B6 deficiency also resulted in significant hypocitraturia.
Asunto(s)
Ácido Cítrico/orina , Glicolatos/orina , Oxalatos/orina , Piruvatos/metabolismo , Deficiencia de Vitamina B 6/metabolismo , Animales , Masculino , Distribución Aleatoria , Ratas , Ratas Wistar , Urolitiasis/metabolismoRESUMEN
We studied whether urinary oxalate excretion after an acute oral load of oxalic acid is influenced by concomitant administration of calcium in rats. Male Wistar rats weighing approximately 180 g were divided into six groups of five animals each. After inducing anesthesia, the animals were orally (via a gastrostomy) given 110 micromol of oxalic acid along with 0, 27.5, 55, 110, or 220 micromol of calcium (0, 27.5, 55, 110, or 220 micromol Ca group, respectively). Saline was given to the control group instead of oxalic acid. Urine specimens were collected before administration and then at hourly intervals up to 5 h afterward. Urinary oxalate and citrate levels were measured by capillary electrophoresis, while urinary calcium, magnesium, and phosphorus levels were measured by ICP spectrophotometry. Urinary oxalate excretion peaked at 1 h after administration and was higher in the 0, 27.5, and 55 micromol Ca groups than in the control group. The urinary recovery of oxalate in these groups was 10-15%, while the recovery rate was less than 3% in other groups. Urinary Ca excretion showed no significant changes, either over time or between groups. Free oxalic acid is absorbed more readily from the gastrointestinal tract than calcium oxalate, while simultaneous administration of calcium appears to block intestinal oxalic acid absorption in a dose-dependent manner.
Asunto(s)
Calcio de la Dieta/farmacología , Absorción Intestinal , Ácido Oxálico/farmacocinética , Animales , Relación Dosis-Respuesta a Droga , Masculino , Ratas , Ratas WistarRESUMEN
Different autoimmune mechanisms may be involved in childhood- and adult-onset type 1 diabetes. Our aim was to explore the differences in IA-2 autoantibody epitope recognition between childhood- and adult-onset type 1 diabetes. Therefore, in vitro synthesized radiolabeled IA-2ic (amino acid 601-979), IA-2JM (amino acid 557-629), and IA-2PTP (amino acid 630-979) were used to analyze the IA-2 autoantibody epitope specificities in 93 patients with new-onset type 1 diabetes. Among 93 patients with type 1 diabetes the prevalences of autoantibodies to GAD, IA-2ic, and insulin were 69.9%, 58.1%, and 45.2%, respectively. The prevalence of IA-2ic autoantibodies in patients with childhood-onset type 1 diabetes (aged Asunto(s)
Autoanticuerpos/inmunología
, Diabetes Mellitus Tipo 1/inmunología
, Diabetes Mellitus Tipo 2/inmunología
, Epítopos/inmunología
, Adolescente
, Adulto
, Edad de Inicio
, Especificidad de Anticuerpos
, Niño
, Diabetes Mellitus Tipo 1/fisiopatología
, Diabetes Mellitus Tipo 2/fisiopatología
, Femenino
, Glutamato Descarboxilasa/inmunología
, Humanos
, Insulina/inmunología
, Isoenzimas/inmunología
, Masculino
, Persona de Mediana Edad