Maria Luisa Gozzo

Determination of copper, zinc, and selenium in human plasma and urine samples by potentiometric stripping analysis and constant current stripping analysis

Potentiometric stripping analysis and constant current stripping analysis are proposed as routine methods for analysis of copper, zinc and selenium in plasma and urine samples. The analytical performance of these methods is comparable with that reported for atomic absorption spectrometry. However the low cost, greater simplicity of the apparatus, and the facility of execution make this methodology a valid candidate for routine application in Clinical Chemistry laboratories.

Plasma levels of coenzyme Q(10), vitamin E and lipids in uremic patients on conservative therapy and hemodialysis treatment: some possible biochemical and clinical implications.

Coenzyme Q(10) (CoQ(10)), vitamin E, total cholesterol, HDL-cholesterol (HDLC) and triglycerides were measured in the plasma of 62 patients with kidney failure, 46 under hemodialysis treatment and 16 under conservative therapy, and 95 controls. The sum of LDL-cholesterol (LDL-C) and VLDL-cholesterol (VLDL-C) was also calculated for each patient. The ratio CoQ(10)/LDL-C+VLDL-C in both conservative therapy and hemodialysis populations was significantly lower (P<0.001) compared with normal controls and remained unchanged after the dialysis treatment. On the contrary the ratio vitamin E/LDL-C+VLDL-C was normal but decreased significantly (P<0.02) after each dialysis. Since coenzyme Q is the main inhibitor of the prooxidant action of vitamin E, it was hypothesized that its decrease in both the populations examined could make the lipoproteins of these patients more vulnerable to a peroxidative attack.

The Oxidative Metabolism of Antarctic Fish: Some Peculiar Aspects of Cold Adaptation

Environmental factors are key determinants in the process of adaptation and evolution of living organisms. In this respect, analysis of biological systems from Antarctic fish may provide valuable insights on the molecular and cellular strategies which have been adopted in response to the very low environmental temperature which characterizes Antarctica. Hence, the temperature of the Antarctic Ocean varies from −1.86 °C at high latitudes to +5 °C towards the Antarctic Convergence. Moreover, seasonal variations in temperature are less than 0.2 °C close to the permanent ice shelf [1] and only 2.5 °C in the northern Antarctic [2]. Very likely these conditions have existed relatively unchanged for several million years [3]. Antarctic fish have therefore been forced to become highly specialized to cold conditions [4]. This extreme specialization is outlined by the fact that a water temperature of −1.8 °C, near the freezing point of sea water, is a condition which would be lethal for virtually all other fish. Among antarctic fishes the strong challenge of this extreme environmental condition has been overcome by a number of physiological and biochemical adaptation mechanisms, the most striking of which is the synthesis of freezing-point depressing molecules (antifreeze molecules), either peptides or glycopeptides, which protect the organism from ice crystal formation in a noncolligative way [5]. In addition, hematocrit of the blood is either substantially reduced or erythrocytes and hemoglobin are absent as in Channichthyidae [6, 7, 8].

Coenzyme Q homologs and trace elements content of Antarctic fishes Chionodraco hamatus and Pagothenia bernacchii compared with the mediterranean fish Mugil cephalus

Coenzyme Q and trace element contents of two antarctic fishes (Pagothenia bernacchii and Chionodraco hamatus) were investigated and compared with that of one temperate marine fish (Mugil cephalus). In particular, muscle and erythrocyte concentrations of coenzyme Q, vitamin E, selenium, copper and zinc were determined. Antarctic fishes showed, at the level of their muscles, higher levels of selenium, zinc and copper compared with M. cepalus. In antarctic fishes, in the place of Q10, the coenzyme Q form generally observed in temperature fishes, only the homolog coenzyme Q9 was found. This particular finding has been related to the difference in the crystallization temperature existing between CoQ10 and CoQ9. Moreover, the high levels of zinc and selenium, observed in C. hamatus, correlate very well with a recent report on the presence, in the liver of this fish, of a zinc-binding protein that, in addition, is characterized by an amino acid sequence closely similar to that of a selenium-containing protein isolated from ovine heart. All together, the results indicate, for the antarctic species, a high level of antioxidant defenses with respect to the mediterranean fish and may be considered as a stimulating basis for further studies on the oxidative metabolism of Antarctic organisms.

Effects of Dental Methacrylates on Oxygen Consumption and Redox Status of Human Pulp Cells

Several studies have already demonstrated that the incomplete polymerization of resin-based dental materials causes the release of monomers which might affect cell metabolism. The aim of this study was to investigate the effects of triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, urethane dimethacrylate, and 2-hydroxyethyl methacrylate on (1) cellular energy metabolism, evaluating oxygen consumption rate, glucose consumption, glucose 6-phosphate dehydrogenase activity, and lactate production, and (2) cellular redox status, through the evaluation of glutathione concentration and of the activities of enzymes regulating glutathione metabolism. Methods. Human pulp cells were used and oxygen consumption was measured by means of a Clark electrode. Moreover, reactive oxygen species production was quantified. Enzymatic activity and glucose and lactate concentrations were determined through a specific kit. Results. Triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and 2-hydroxyethyl methacrylate induced a decrease in oxygen consumption rate, an enhancement of glucose consumption, and lactate production, whilst glucose 6-phosphate dehydrogenase and glutathione reductase activity were not significantly modified. Moreover, the monomers induced an increase of reactive oxygen species production with a consequent increase of superoxide dismutase and catalase enzymatic activities. A depletion of both reduced and total glutathione was also observed. Conclusion. The obtained results indicate that dental monomers might alter energy metabolism and glutathione redox balance in human pulp cells.

Enzymatic determinations in acute rejection after liver transplantation: preliminary report on necrosis index

The catalytic activities of some mitochondrial and cytoplasmic enzymes were measured in plasma from 19 patients after orthotopic liver transplantation, in order to detect and monitor the evolution of hepatocellular damage and to predict liver rejection. The enzymatic activities determined were: mitochondrial isoenzyme of aspartate aminotransferase, glutamate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyltranspeptidase and alkaline phosphatase. The results of all enzymatic activities were normalized by expressing them as multiples of the upper limit of the relevant reference range and then the necrosis index (NI) has been calculated. The proposed NI consists of percent ratio of the normalized mitochondrial enzymatic activities over the sum of cytoplasmic and mitochondrial normalized activities. We observed that NI values higher than 30% correctly identified all but two acute rejection events which were documented by liver biopsies showing a diagnostic sensitivity of 90%, specificity of 78% and a predictive value of 90%.

Multimodal approach in invasive fetal therapy.

BACKGROUND Integrated fetal therapy is a new approach to prenatal management consisting of a combination of invasive procedures which complement each other to provide as much information as possible on the fetal compartments. METHODS We carried out a study on 50 fetuses of singleton pregnancies undergoing invasive procedures -- at least three per fetus -- for diagnostic and therapeutical purposes. A total of two hundred and fifty invasive procedures were adopted. The study population was divided into two groups, those studied between 1988 and 1992 and those studied between 1993 and 1995. RESULTS The diagnostic and therapeutic utility of complementary invasive procedures in fetuses with nonimmune fetal hydrops and urinary tract malformations was assessed. In fetuses with nonimmune fetal hydrops integrated invasive procedures markedly affected the fetal-neonatal survival rate, whereas in those with urinary tract malformations scheduled for postnatal surgery these procedures made it possible to limit intrauterine renal damage. CONCLUSIONS Complementary invasive procedures in NIFH fetuses particularly influence the fetal-neonatal survival rate. Since urinary tract malformations must be treated by postnatal surgery, complementary invasive procedures serve to limit intrauterine renal damage in the meantime and to reduce cesarean section rate.

Automation in urinalysis: sample and data management, and quality control

Reagents: Urine reagent strips Uriflet 7A DIC, Check Sample Set (used for calibration control of Aution analyser) and Rifra-Chek Solutions for calibration and control of Urinometer lot 040 (all by Kyoto, Daiichi, Kagaku Co. Ltd, distributed in Italy by Menarini of Firenze). Urine Controls: Kova Trol 1, Kova Trol 2, and Kova Trol 3: Human Urine (dried) manufactured by ICL Scientific, 18349 Euclid, Fountain Valley, California 92708, USA (distributed in Italy by Boehringer Biochemia Robin Diagnostic Division, Milano).

Use of N-(l-naphthyl)-ethylendiamine-dihydrochloride (NEDD) as secondary calibrator for conjugated bilirubin on the DuPont aca.

N-( 1-naphthyl)-ethylendiamine-dihydrochloride (NEDD) and its derivatives have been used as secondary calibrators for continuous-flow analytical instruments (for example Technicon’s SMAC) [1]. These molecules are known to react with the diazonium salts, yielding azoderivatives which have spectral qualities similar to those of azobilirubin. NEDD has also successfully been employed in the authors’ laboratory as secondary calibrator for conjugated bilirubin on a discrete clinical analyser: the Hitachi 706 [2].

A computer program for intra-laboratory quality control.

Intra-laboratory quality-control (intra-lab QC) is the best way of checking the performance of single components of analytical systems (methods, instruments, technicians) [1]. However, the time-consuming and tedious statistical methods necessary, if manually performed, provide late information that reduces the validity of intra-lab QC. In order to make this type of quality control more useful, a minicomputer program, which automates mathematical and graphical procedures, has been developed. The program assures rapid, unique and unequivocal interpretation ofresults by using a reliability index (RI) I-2 and 3-1. cumulative sum of RIs. Its value progressively increases if there is no variation in the RI sign; it begins again from zero if a sign variation appears. The statistical parameters are calculated monthly to allow retrospective quality-control. Monthly means and standard deviations on untruncated, truncated, and the cumulated results of two control materials are calculated. Truncated data means and related standard deviations are obtained after an iterative truncation deletes outliers (+ 3 SD). The truncated data are summed with those from the previous months and are used to calculate cumulative means and standard deviations. Control charts [7], and two sample plots [8] are printed by means ofthe P6060’s printer.