Improvement and validation of d-xylose determination in urine and serum as a new tool for the noninvasive evaluation of lactase activity in humans.

BACKGROUND: The phloroglucinol assay is the current method for d-xylose determination in urine/plasma/serum. However, its sensitivity is limited when low amounts of d-xylose are to be measured, such as in the noninvasive evaluation of intestinal lactase with 4-galactosylxylose (gaxilose). An improved assay was therefore needed. METHODS: We developed and validated a modified version of the phloroglucinol-based assay for quantification of d-xylose in urine/serum samples. A method for gaxilose determination by gas chromatography (GC) was also optimized. RESULTS: Linearity ranged from 0.125 to 5.0 mg/l (5-200 mg/l in original sample). Accuracy at LOQ (0.125 mg/l) was 0.97/2.49% in spiked urine/serum; for other quality controls (QC), it was <1.27%. Intra- and interassay precision at LOQ were 6.02% and 6.45% for urine, and 8.86% and 10.00%, respectively, for serum; for other QC, precision was <2.15%. Linearity of gaxilose determination by GC was 3.90-195.17 for urine and 9.75-195.17 mg/l for serum with acceptable sensitivity and reproducibility. The method proved adequate for the d-xylose determination in healthy and hypolactasic subjects after oral administration of gaxilose. CONCLUSIONS: The modified method provides high sensitivity and robustness for d-xylose quantification in urine/serum for routine clinical use especially in the noninvasive diagnosis of intestinal lactase deficiency with the gaxilose test.

Adequate hydration status promotes a lower concentration of proinflammatory cytikines in healthy adults / Una adecuada hidratación promueve una menor concentración de citoquinas proinflamatorias en adultos sanos

Background: Good hydration status (HS) is necessary for an adequate homeostasis of the organism. Cytokines are secreted mainly by inflammatory leukocytes and act as intercellular mediators. Objetive: Assessing pro and anti-inflammatory cytokines concentration in serum and in the aqueous phase of stools (APhS) from healthy adults in function of their HS. Methods: HS data were obtained from 86 healthy adults of 45-65 years old and BMI ≥18.5-<40 kg/m2. HS was measured by bioelectrical impedance (BIA) with a standardized protocol. Cytokines serum concentrations were determined by multiple ELISAs. Stools were recollected by the participants, frozen, and carefully transported to the laboratory where they were stored at -80°C until their determination. Stools were ultra-centrifuged and cytokines were measured in APhS with an ultra-sensible cytokines array. All samples were analyzed in duplicate. Results: Mean age was 51.2 ± 4.9 years old and BMI was 28.2 ± 4.7 kg/m2. The average intake of water from foods and beverages was not adequate enough (1,411.6 ± 427.4 ml/day; 81% consumed less than two-thirds of the recommended intake) however only 89.5% showed an adequate HS and only 10.5% showed clearly dehydration measured by BIA. Volunteers who had good HS had lower values of IFN(2.7 ± 2.4 vs 6.4 ± 4.3 pg/ml; p < 0.05) and IL6 serum (5.5 ± 13.3 vs 6.4 ± 16.3 pg/ml; p < 0.01) than those who had a dehydration status. IL1 from AphS showed lower values in adults with good hydration than those dehydrated (648.3 ± 615 vs 1,194 ± 561.2 pg/ml; p < 0.05). Conclusions: Adults with an appropriate HS have a minor concentration of pro-inflammatory cytokines in serum and in APhS than adults who showed a dehydration status. More studies are needed in order to corroborate these results (AU)

Introducción: Un adecuado estado de hidratación (EH) es necesario para mantener la homesostasis del organismo. Las citoquinas son mediadores intercelulares que son secretadas principalmente por leucocitos. Objetivo: Valorar la concentración de citoquinas pro y antiinflamatorias en suero y la fase acuosa de las heces (FAH) de adultos sanos en función de su EH. Métodos: Se obtuvo información sobre el EH de 86 adultos sanos de 45-65 años y un IMC de 18,5-<40 kg/m2. El EH fue medido por Impedancia Bioeléctrica (BIA) siguiendo el protocolo estándar. La concentración de citoquinas en suero fue determinada por múltiples ELISAs. Las heces fueron recolectadas por los participantes, congeladas y transportadas al laboratorio donde fueron almacenadas a -80°C hasta su determinación. Posteriormente las heces fueron ultracentrifugadas y las citoquinas fueron medidas en la FAH con un array ultrasensible. Resultados: La edad media fue de 51,2 ± 4,9 años y el IMC fue de 28,2 ± 4,7 kg/m2. El consumo medio de agua proveniente de los alimentos y las bebidas realizado por los participantes no fué suficiente (1.411,6 ± 427,4 ml/día; el 81% consumió menos de dos tercios de la ingesta recomendada), sin embargo, el 89,5% presentó un adecuado EH y solo el 10,5% estuvo en rango de deshidratación. Los participantes con un adecuado EH tuvieron valores de IFN(2,7 ± 2,4 vs 6,4 ± 4,3 pg/ml; p < 0,05) e IL6 séricos (5,5 ± 13,3 vs 6,4 ± 16,3 pg/ml; p < 0,01) inferiores a las personas deshidratadas. La IL1 medida en la FAH mostró una concentración más baja en personas bien hidratadas que en aquellas deshidratadas (648,3 ± 615 vs 1194,0 ± 561,2 pg/ml; p < 0,05). Conclusiones: Los adultos de nuestro estudio con un adecuado EH presentan una concentración inferior de citoquinas proinflamatorias en suero y en la FAH que aquellos que estaban deshidratados. Se necesitan más estudios que confirmen estos resultados (AU)

Phenobarbital pretreatment increases thioacetamide induced necrosis and postnecrotic regeneration in rats

Uno de los aspectos más importantes de las interacciones de fármacos es la habilidad de algunos de ellos de inducir las monooxigenasas microsomales hepáticas e incrementar la toxicidad de otras drogas. Se administró a las ratas una dosis única de tioacetamida por vía intraperitoneal (500 mg/Kg de peso) para provocar una necrosis y regeneración hepática; sobre este modelo experimental se estudió la influencia de la administración intraperitoneal de fenobarbital (80 mg/ Kg/día) durante los cinco días previos a la administración de la tioacetamida. Los resultados muestran que el pretratamiento con fenobarbital incrementó el daño hepático provocado por la tioacetamida, como se demuestra por los incrementos de las actividades enzimáticas en suero, niveles totales de bilirrubina y por la extensión del área necrótica en la región acinar perivenosa. Este mayor daño hepático fue paralelo al incremento de la respuesta regenerativa del tejido como queda demostrado por el aumento de la síntesis de DNA y por el nivel de α-fetoproteína en suero. Podemos concluir que el pretratamiento con fenobarbital aumenta la hepatotoxicidad y la regeneración hepatocelular, sin embargo, no modifica ni la localización acinar ni el patrón temporal del daño hepático y regeneración inducida por la tioacetamida. Además, tanto la respuesta proliferativa como los cambios en las poblaciones diploides y poliploides, fueron más pronunciados en los hepatocitos pretratados con fenobarbital

One of the most important events related to drug interactions is the ability of some drugs to induce hepatic microsomal monooxygenases and to increase the toxicity of other drugs. A single intraperitoneal dose of thioacetamide was administered to rats (500 mg/Kg) to induce liver necrosis and regeneration; and on this experimental model the influence of intraperitoneal phenobarbital administration (80 mg/Kg/day) for five days before thioacetamide was studied. The results show that phenobarbital pre-treatment increased liver damage induced by thioacetamide, as detected by increases in serum enzymatic activities, levels of total bilirubin, and by the extent of the necrotic area in the perivenous acinar region. The higher liver injury was parallel to the higher rate of tissue regenerative response as demonstrated by the rate of DNA synthesis in hepatocytes and the level of α-fetoprotein in serum. We can conclude that phenobarbital pre-treatment enhanced hepatotoxicity and hepatocellular regeneration, but did not change either acinar location or timing of liver injury and regeneration induced by thioacetamide. Moreover, the proliferative response as well as the changes in diploid and polyploid populations, were more pronounced in phenobarbital pretreated hepatocytes