Tomas De Paoli

Zinc as an essential micronutrient : A review

Zinc is one of the most important essential tracer metals of human nutrition, and its deficiency is a world nutritional problem. This work compiles past and present information about the role of zinc in human health.

Zinc and diabetes mellitus: is there a need of zinc supplementation in diabetes mellitus patients?

Diabetes mellitus is a group of metabolic disorders, the incidence of which varies widely throughout the world. The treatment of diabetes mellitus includes insulin, oral antidiabetic agents, and dietary regimens. Although the emphasis is on macronutrients intakes, there is strong evidence that there is an abnormal metabolism of several micronutrients in diabetic individuals. Zinc is one of the essential micronutrients of which status and metabolism is altered in this condition. This work is a short review about the close relation among zinc, glucose metabolism, and insulin physiology, as well as about the few experimental data about zinc absorption and zinc supplementation in diabetes mellitus patients.

Bioavailability, biodistribution, and toxicity of biozn-aas: a new zinc source. comparative studies in rats

Food fortification with a proper zinc compound is an economic and effective strategy to prevent zinc deficiency. BioZn-AAS, a zinc gluconate stabilized with glycine, was compared with zinc sulfate (reference standard), zinc hydroxide, and zinc gluconate, all of them labeled with (65)Zn. This preclinical study was performed on Sprague-Dawley rats of both sexes, and the administered dose was 85 microg/kg of zinc. Bioavailability studies showed that absorption of BioZn-AAS was not statistically different than absorption from other sources in female rats (25.65% +/- 2.20% for BioZn-AAS, 28.24% +/- 4. 60% for ZnSO(4), 24.91% +/- 4.02% for Zn[OH](2), and 25.51% +/- 2. 70% for Zn-gluconate). In the case of the male rats, absorption of BioZn-AAS (27.97% +/- 4.20%) was higher (P<0.05) than that from the other compounds (23.15% +/- 2.90% for ZnSO(4), 22.62% +/- 3.90% for Zn[OH](2), and 22.30% +/- 3.90% for Zn-gluconate). Biodistribution studies demonstrated that the zinc from BioZn-AAS followed the same metabolic pathway as zinc from the other sources. Toxicity studies were performed with 50 female and 50 male rats. The value of oral lethal dose 50 (LD(50)) was 2000 mg/kg for female rats and 1900 mg/kg for male rats. Therefore, we conclude that BioZn-AAS has adequate properties to be considered a proper zinc compound for food fortification or dietary supplementation.

Long term production of reactive oxygen species during perinatal asphyxia in the rat central nervous system: Effects of hypothermia

The formation of oxygen-derived free radicals in hypoxic and ischemic/reperfused brains has been proposed as an important step that links brain injury to neuronal death. Previously, we have demonstrated that reactive oxygen species (ROS) production was significantly increased in rat neostriatum during acute perinatal asphyxia (PA) in pups. In this article, we have studied the time course of ROS production in the neostriatum and neocortex of adult rats subjected to PA using electron spin resonance spectrometry (ESR) in order to record ROS production. Further more, we analyzed the actions of hypothermia on ROS release in pups and adult rats. We used for this study 6-month-old rats that suffered sub-severe and severe PA when they were pups. The most significant production of ROS was detected either in the neostriatum or neocortex at 19 and 20 min of PA. Hypothermia during 20 and 100 min at 15°C prevented ROS formation either in pups and adult rats. These data further support the concept that free radicals may contribute to the brain injury alterations and that hypothermia can prevent long-term sequelae induced by PA.

Bioavailability, biodistribution and toxicity of biocalTM♣ a new calcium source. Comparative studies in rats

Abstract The purpose of this study is to determine the bioavailability, biodistribution and toxicity of Biocal™, a new calcium source. Biocal™ is a calcium gluconate stabilized with glycine. A comparative study of this compound versus calcium gluconate was performed in Sprague-Dawley rats. Bioavailability studies were carried out by the labeling of both compounds with 45 Ca. We administered a dose of 30 mg of Ca per kg of body weight p.o. to two groups of 7 male adult rats each. The urine elimination of the 45 Ca, expressed as total accumulated percentage of 45 Ca activity in urine (Ae ∞ ), between the rats that received Biocal™ (Ae ∞ = 2.436±1.337 %) and the rats that received calcium gluconate (Ae ∞ = 1.241±0.473 %) were found to be statistically different (p 50 for female rats was 13.5 g/kg with a lower limit of 12.8 g/kg and upper limit of 14.3 g/kg. In the case of male rats the LD 50 was 13.0 g/kg with a lower limit of 12.2 g/kg and upper limit of 13.9 g/kg. These values are higher with regard to the oral LD 50 for calcium gluconate (10 g/kg). Our results demonstrate that calcium from Biocal™ has a higher bioavailability with the same metabolic behavior than calcium from calcium gluconate. The value of oral LD 50 shows that the toxicity of Biocal™ is lower than that of the calcium gluconate. Therefore we conclude that Biocal™ has adequate properties to be considered as a promissory calcium compound to be used as dietary supplement or for food fortification.

Determination of the Volume of the Blood of Rabbits and Pigs Using Electron Spin Resonance

Blood volume of rabbits and pigs was determined by an electron spin resonance (ESR) measurement of erythrocytes spin labelled by attaching the radical ion 4-maleimido-2,3,6,6,-tetramethylpiperidine-1-oxyl (MAL-4) to reduced glutathione. All correction factors were considered in detail, including the stability of MAL-4 in erythrocytes inside and outside the blood stream (by taking multiple blood samples and measuring the strength of the signal). It was found that exercise and certain anesthetics (Midazolam, pentobarbitone (rompum), Ketamine) did not affect the in vivo stability. Some measurements were taken to determine how fast the fluid lost after haemorrhage is replaced in the blood stream as well as when the excess fluid after transfusion is removed from the blood stream. The time decay data were fitted to stretched exponential functions. This method of blood volume determination is believed to be superior to the usual radioactive labeling method.

GLUTATHIONE DECAY IN STORED BLOOD MEASURED BY ELECTRON SPIN RESONANCE

An electron spin resonance has been developed by our group which employs spin labeled erythrocytes to study the decay of glutathione in stored blood. The results are compared with determinations made by the usual optical method. The values of the glutathione concentration C(t) in the blood fit the stretched exponential equation.

Oxidative stress and membrane fluidity in erythrocytes from patients with hemolytic uremic syndrome

C\left( t \right) = \left( {C_0 - C_f } \right)e^{ - \left( {\frac{t}{\tau }} \right)^n } + C_f

Liposomes containing bioavailable iron (II) and process for obtaining them

where C0 is the initial concentration, at time t=0, Cf is the final concentration at time t→∞, and the constants n and τ have the average values

Conceptos actuales del metabolismo del glutatión Utilización de los isótopos estables para la evaluación de su homeostasis

\begin{array}{l} n = 5.3 \\ \tau = 5.8\,{\rm{days}} \\ \end{array}