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Biomedical subjects

A Bertazzo

Publications and source records attributed to A Bertazzo.

31 records · Page 2Linked to original sources
PubMed1996

Determination of copper and zinc levels in human hair: influence of sex, age, and hair pigmentation.

The Cu and Zn levels of both 607 men (1-85 y old) and 649 women (1-92 y old) were determined by atomic absorption spectrometry. Sex does not influence Cu (14.89 + or - 0.89 mu g/g and 15.26 + or - 0.79 mu g/g hair for males and females, respectively) and Zn contents (200.97 + or - 9.68 mu g/g for men and 209.81 + or - 9.49 mu g/g hair for women). Age influences Cu and Zn concentrations, but only significantly in females: Cu levels decrease over 60 y of age; whereas Zn levels increase significantly from age groups 2-5 to 20-40 years. Hair color influences Cu concentrations in both males and females. In males, white hair contains less Cu than black hair; in females, white hair's Cu levels are significantly lower than those of dark blond, red, light brown, and brown hair. There are no significant differences in Zn concentrations with respect to different hair colors, in either males or females.

Adolescent↗
PubMed1995

Biosynthesis of melanin from dopamine. An investigation of early oligomerization products.

Matrix-assisted laser desorption/ionization (MALDI) and fast-atom bombardment (FAB) mass spectrometry experiments were applied to the study of the early stages of the oligomerization reaction of dopamine with mushroom tyrosinase. Ultrafiltration was employed to remove the enzyme at various reaction times, to prevent possible attachment of the protein to the highly reactive intermediates. Two sets of five samples each, obtained at different reaction times, in one case immediately lyophilized and in the other left to react under an oxygen stream for 24 h before lyophilization, were compared. FAB showed the presence of various species and of these, that at m/z 305 increased in abundance with reaction time in immediately lyophilized set of samples only. Accurate mass measurements and tandem mass spectrometric experiments indicated the structure of a dopamine protonated dimer for this ion. MALDI measurements showed that all samples were composed of clusters of oligomers differing in degree of oligomerization. Oligomerization increases with reaction time, resulting in the formation of species at 2643-2911 Da. These clusters in turn were formed of species with a different degree of oxidation, detected in both sets of samples.

Dopamine↗
PubMed1994

Laser desorption ionization mass spectrometry in the study of natural and synthetic melanins. II--Serotonin melanins.

Various biosynthetic melanins obtained by enzymic oxidation of serotonin with polyphenol oxidase from Psalliota campestris mushroom or potato, and with tyrosinase from Sepia officinalis or from Sigma were studied by means of laser desorption ionization mass spectrometry. Various oligomeric clusters were evidenced, proving that the examined melanins are composed of sets of different oligomers, the production of which strongly depends on the enzyme reaction. While serotonin melanins obtained with polyphenol oxidase from potato showed wide species distribution with molecular weights ranging from 2008 to 13,000 Da, the same melanins obtained from mushroom showed oligomer distributions from 1505 to 9000 Da. Serotonin melanins prepared with tyrosinase from Sepia showed oligomers from 1636 to 18,000 Da. A dopa-melanin obtained with mushroom polyphenol oxidase showed oligomer species from 1709 to 17,874 Da. Comparison of molecular weight distributions of the various oligomer sets in serotonin melanins with those in tyrosine melanins revealed clear differences, which are investigated and discussed.

Agaricus↗
PubMed1993

Laser desorption ionization mass spectrometry in the study of natural and synthetic melanins. I--Tyrosine melanins.

Nine synthetic, biosynthetic and natural tyrosine melanins, together with dopa and catechol melanins, have been studied by means of laser desorption ionization mass spectrometry. The results obtained have shown that all the melanins under study consist of homogeneous sets of oligomers and have led to definitive information on their molecular weight distribution (from 500 to 30,000 Da). A deeper analysis of the spectra, in terms of mass differences among the various oligomers, allowed the identification of some monomeric units, identical or analogous to those already proposed in the literature.

Lasers↗
PubMed1992

Melanin biosynthesis from dopamine. II. A mass spectrometric and collisional spectroscopic investigation.

Electron impact (EI) and fast atom bombardment (FAB) mass spectrometry together with collisional activation (CA) experiments were applied to the study of the oxidation pathway of dopamine by tyrosinase. In order to prevent attachment of the protein to the highly reactive intermediates, ultrafiltration was employed to remove the enzyme at different reaction times. FAB, privileging molecular species formation, was successfully used for identification of transient intermediates and their relative concentrations with respect to time, directly in the reaction mixture. The presence of isobaric molecular species made chromatographic separation necessary. Further EI mass spectrometry and collision spectroscopy led to structural identification of pure components. Of these, dopamine-o-quinone, leucoaminochrome, and aminochrome semiquinone were characterized for the first time as real intermediates in dopamine melanogenesis, in agreement with previous hypotheses. This approach elucidated the pathway of dopamine melanogenesis.

Dopamine↗
PubMed1989

Accumulation of arachidonic acid cyclo- and lipoxygenase products in rat brain during ischemia and reperfusion: effects of treatment with GM1-lactone.

The aim of our study was to investigate the changes of various biochemical parameters (concentrations of lactate, free arachidonate, cyclo- and lipoxygenase products) in rat brain after ischemia and reperfusion and the effects of pretreatment with the ganglioside derivative GM1-lactone on the same parameters. Ischemia was induced by reversible occlusion of common carotid arteries for 20 min, which included a final 5 min of respiration of 5% oxygen in nitrogen. Reperfusion was obtained by removing the occlusion. Pre-ischemic conditions were obtained on sham-operated animals. Animals were killed by microwave irradiation of their heads. Brain levels of lactate and of free arachidonate were markedly increased after ischemia and returned to normal values at 5 min of reperfusion. Levels of the cyclooxygenase metabolites prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 were increased after ischemia, whereas levels of the lipoxygenase metabolite leukotriene C4 (LTC4) did not change. After reperfusion, a very marked increase of the cyclooxygenase products occurred but not of LTC4. Treatment with GM1-lactone prevented the elevation of cyclo- and lipoxygenase metabolites especially during reperfusion, with limited effects on lactate and free arachidonate levels.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

The carbochromene derivative AD6 reduces the TxB2/6-keto-PGF1 alpha ratio in cerebral cortex during hypoxia and recovery and leukotriene synthesis in brain tissue, in the rat.

Pretreatments of rats with the Carbochromene derivative AD6 (4 mg/kg i.p., 2 h before sacrifice) resulted in elevation of brain levels of 6-keto-PGF1 alpha in cerebral cortex under physiological conditions, had no effect on levels of TxB2 and 6-Keto-PGF1 alpha at 30 min of hypoxia (respiration of 5% O2 in N2) and prevented the accumulation of TxB2 occurring in brain at 5 min of recovery after hypoxia. In addition, the accumulation of LTC4 and B4 in brain slices incubated in the presence of the Ca++ ionophore A23187 and arachidonic acid, was reduced in samples obtained from pretreated rats. The drug, thus, had favourable effects on the 6-keto-PGF1 alpha/TxB2 ratio in normal conditions, as well as in conditions of altered oxygen supply. In addition it reduced the formation of compounds, the leukotrienes, which may exert pro-inflammatory activities on the cerebral microcirculation.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Effects of hypoxia and recovery on brain eicosanoids and carbohydrate metabolites in rat brain cortex.

The effects of hypoxia (respiration of 5% O2 for 30 min) and recovery (respiration of air up to 30 min) on brain levels of carbohydrate metabolites, of free arachidonate (FAA) and of several eicosanoids (E) were studied in the rat. Animals were sacrificed before or after 30 min of hypoxia, and during recovery, by microwave radiation (MW). At the end of the hypoxic period, arterial pO2 was reduced to 28 mm Hg and glycemia was elevated. Brain lactate and glucose levels were also elevated, whereas glycogen was unchanged. Levels of free FAA and of E were practically unchanged. During recovery, arterial pO2 values were raised above prehypoxic levels at 5 min and returned to normal within 30 min. The elevated serum glucose declined at 5 min and values returned to normal at 30. Brain glucose was still elevated at 5 min and returned to normal, together with lactate, at 30 min. Brain FAA did not change during recovery, but levels of prostaglandin F2 alpha (PGF2 alpha), prostaglandin E2 (PGF2) and thromboxane B2 (TxB2) were raised, at 5 min, and those of 6-keto-PGF1 alpha were reduced with respect to pre-hypoxia. At the end of recovery, all E were lower than during hypoxia. The results indicate that changes of brain E occur only during recovery from hypoxia. At 5 min of recovery, at high arterial pO2 values, concentrations of all E were elevated, with the exception of 6-keto-PGF1 alpha which was reduced. At 30 min a marked reduction of E levels was observed, possibly resulting from increased clearance following elevation of cerebral blood flow.

Animals↗
PubMedDate not supplied

Tryptophan, copper and zinc in hair of healthy subjects. Correlation with differences in hair pigmentation.

Tryptophan, copper and zinc levels were determined in the hair of 300 healthy subjects divided by sex, age and hair colour. Sex influences tryptophan content in hair, the levels of this amino acid being higher in males than in females. Tryptophan is also higher in infancy (2-5 years) and in both males and females aging around 80 years and over. Hair colour also influences tryptophan levels, which increase from fair to black hair. Copper levels are similar in hair of both males and females, while those of zinc are higher in women. Age influences the distribution of these two metals in human hair. Copper contents in hair of males are higher at the age 20-40 years. In females, values decrease over the age of 60 years. Instead, zinc levels are higher between 20 and 60 years in males, and between 13 and 19 years in females. As regards hair colour, copper is slightly higher in black hair in males and in fair hair in females, and lower in white hair in both sexes. Zinc values appear to be higher in red and lower in white hair in males. In females they are higher in black hair.

Adolescent↗