Speciation of inorganic arsenic in alimentary and environmental aqueous samples by using derivative anodic stripping chronopotentiometry (dASCP).

The purpose of this research was to develop a sensitive and accurate chronopotentiometric method at a gold film electrode, to determine trace and ultra trace levels of As(III) and As(V) in alimentary and environmental water systems. As(III) was directly determined in the aqueous matrix at a deposition potential of -300 mV for 180 s and at a constant anodic current of 2.5 microA, without any sample pre-treatment; moreover the chronopotentiometric method did not require a time-consuming de-oxygenation step prior to the analysis. A 3M HCl solution was chosen as the best stripping medium. The direct analysis of As(V) required the application of a high negative over-potential and, thus, measurements were characterized by poor reproducibility; therefore As(V) was determined after reduction to As(III) with KI in a strong hydrochloric acid solution. Under the optimised electrochemical conditions, detection limits of 0.08 microg As(III) l(-1) were achieved and no significant interferences from Cd, Cu, Pb, Zn and organic substances were observed. As(V) was the most abundant species in all the studied environmental and alimentary aqueous matrices. Amongst the beverages, tea and coffee presented the As(V) highest concentration ranges (934-1740 microg l(-1) and 850-1290 microg l(-1), respectively) while bottled mineral water the lowest (<1.61 microg l(-1)); whereas As(III) levels lower than 5.0 microg l(-1) were detected only in wine samples.

Influence of calcium on fungal growth, hyphal morphology and citric acid production in Aspergillus niger.

Addition of 0.5 g/L CaCl2 to the fermentation medium lowered the final biomass dry mass by 35% and increased the uptake of phosphate and sucrose, and the production of citric acid by 15, 35 and 50%, respectively. In a medium deprived of Ca2+ the microorganism displayed both a pelleted and a filamentous form of growth, the hyphae being scarcely branched, without bulbous cells. An addition of Ca2+ induced a pelleted form of growth, highly branched hyphae and numerous bulbous cells. Bulbous cells growing in the presence of Ca2+ exhibited cell walls composed of laminated layers, and featured vesicles associated with the wall and/or the cell membrane, containing numerous inclusions. The cytotoxic effect of high concentrations of citric acid in the medium as well as an increase of the activity of N-acetyl-beta-D-glucosaminidase, a lytic enzyme, might be involved in these morphological changes.

In postmenopausal osteoporosis the bone increasing effect of monofluorophosphate is not dependent on serum fluoride.

According to previous pharmacokinetic studies the bioavailability of fluorine (F) from sodium monofluorophosphate (MFP) doubles that of sodium fluoride (NaF). This paper reports a study designed to verify whether the vertebral bone mass increasing effect of NaF (30 mg F/day) was comparable to that of MFP (15 mg F/day), given for 18 months to osteoporotic postmenopausal women. The BMD of lumbar vertebrae of both groups showed significant increases (MFP: 60 +/- 15 mg/cm2, NaF: and 71 +/- 12 mg/cm2) over basal levels (P < 0.001). The difference between treatments was not significant (P = 0.532). The serum levels of ionic F (the mitogenic species on osteoblasts) were not related to the above mentioned effects. In NaF-treated patients, the fasting levels of total serum F increased significantly (6.7 +/- 0.9 microM vs. Basal: 2.0 +/- 0.8 microM; P < 0.001). This phenomenon was accounted for by ionic fluoride that increased over 20-fold (6.5 +/- 1.9 microM vs. Basal: 0.3 +/- 0.04 microM). In MFP-treated patients the fasting serum levels of total (7.0 +/- 0.7 microM vs. Basal: 2.2 +/- 0.9 M) and diffusible F (0.5 +/- 0.02 microM vs. Basal 0.2 +/- 0.02 microM) increased significantly (P < 0.001). The increase in the non diffusible F fraction is accounted for by protein-bound F, probably by the complexes formed between MFP and alpha 2-macroglobulin and C3. Serum diffusible F was formed by two fractions: ionic F and F bound to low molecular weight macromolecule/s (2,200 +/- 600 Da), in approximately equal amounts. The general information afforded by the present observations support the hypothesis that ionic F is released progressively during the metabolism of MFP bound to alpha 2-macroglobulin and C3. These phenomena explain why comparable effects to those obtained with 30 mg F/d of NaF could by obtained with one half the dose of MFP.

Bone morphometry and differences in bone fluorine containing compounds in rats treated with NaF and MFP.

Sodium fluoride (NaF) and sodium monofluorophosphate (MFP) are drugs used to increase bone mass. They have been considered equivalent but the results of the treatments were not always coincident. Most studies have been carried out in osteoporotic women or ovariectomized rats pointing to the result in bone mass rather than at the mechanism of action. Convincing evidence indicates that pharmacokinetic of NaF is different from MFP. While only fluoride is found in bones and plasma of rats treated with NaF, in MFP-treated rats, there are also fluorine (F) bound to plasma alpha-macroglobulin and bone covalently bound F. A significant increase in bone mass of rats was observed after 30 days of treatment with NaF and MFP in young rats. This increase in bone mass correlates with the increase in number and thickness of trabeculas in cancellous bone. In the femur of MFP-treated rats, there was an increase in the inertia momentum of the diaphysis without changes in bone width. In addition, bone F content of MFP-treated animals is twice of the content of NaF-treated rats. This difference is the consequence of bone covalently bound F, which is absent in NaF-treated rats. In addition, alpha-macroglobulin was detected in noncollagenous bone matrix of MFP-treated rats. Although F in feces and plasma did not differ among treatments, the urinary excretion of F was lower in MFP than in NaF-treated rats, which is consistent with the higher bone F content.

Statistical study of the influence of fungicide treatments (mancozeb, zoxamide and copper oxychloride) on heavy metal concentrations in Sicilian red wine.

The aim was to assess the influence of mancozeb, zoxamide and copper oxychloride fungicide treatments on Mn, Zn, Cu, Cd and Pb concentrations in Sicilian red wines, grapes, marcs and grape stalks. The experimentation was carried out over two crop years: 2003 and 2004. Trace metals analysis was performed by derivative stripping chronopotentiometry, which allowed detection of concentrations lower than 1 ng g(-1). The data obtained gave evidence that the levels of Mn and Zn in wines from plots treated with zoxamide-mancozeb were about threefold higher than those observed in the control. Wines treated with Cu oxychloride had a significant increase in Cu(II) concentrations with respect to the control; in particular, samples from 2004 showed a 50% increase in Cu levels. Furthermore, as shown in a previous paper, the fungicides treatments studied led to a moderate increase in Pb(II) and Cd(II) levels in treated samples with respect to the control. Wines from 2004 had higher Cu and Pb amounts than wines from 2003; but the concentrations of all the other metals were similar. Statistical analysis of the data by linear discriminant analysis (LDA) and the Kruskal-Wallis test confirmed that both zoxamide-mancozeb treatments and copper oxychloride treatments exerted a significant influence on Mn(II), Zn(II) Cu(II), Pb(II) and Cd(II) concentrations in wines, grapes, marcs and grape stalks samples from both the studied vintages.

Influence of roasting and different brewing processes on the ochratoxin A content in coffee determined by high-performance liquid chromatography-fluorescence detection (HPLC-FLD).

A rapid and reliable procedure has been developed for the determination of ochratoxin A (OTA) in green and roasted coffee. The method consists of extraction of the sample with methanol-5% aqueous sodium hydrogen carbonate/1% PEG8000 (20:80), followed by immunoaffinity column (IAC) clean-up and, finally, high-performance liquid chromatography (HPLC) determination with fluorimetric detection. Mean recoveries for green and roasted coffee spiked at different levels ranging from 94 and 105% were obtained. The limit of determination (S/N = 3) was 0.032 ng g(-1) and the precision (within-laboratory relative standard deviation) was 6%. The method described has been used to assess the influence of roasting and different brewing processes on OTA content in commercial lots of green and roasted coffee. The results provided evidence that roasting led to a significant drop on OTA levels (65-100%). Also, the way coffee is prepared affects the OTA content: brewing using a Moka Express (Italian coffee) led to a significant reduction of OTA concentration (50-75%) since hot water stays in contact with coffee for a short time. On the contrary, Turkish coffee-making (infusion for about 10 min) cause poor reduction in OTA.

Organochlorine pesticides and polychlorinated biphenyl residues in reared and wild Dicentrarchus labrax from the Mediterranean Sea (Sicily, Italy).

The aim of this research was to compare the levels of organochlorine pesticides and PCBs in samples of Dicentrarchus labrax living in the Straits of Messina with samples cultivated in cages in the Mediterranean Sea. Muscles and liver tissues sampled over the months, within the same year, were analyzed. The quantitative determination of the organochlorine compounds was performed by GC-ECD and confirmed with GC-MS. The results showed that the concentrations of DDTs in muscles and livers as such of reared sea bass were in the range 0.2-1.3 microg/kg and 9.6 -48.4 microg/kg, respectively. In wild fish the concentrations of DDTs were very much lower: 0.1 microg/kg in muscles, 5.1-9.0 microg/kg in livers. Total PCBs levels were higher in cultivated sea bass than in wild fish; the concentration ranges were 5.3-59.7 microg/kg and 74.4-267.4 microg/kg in muscle and liver of reared samples, respectively, and 1.1-1.5 microg/kg and 63.2-109.4 microg/kg in muscle and liver of wild samples, respectively.

The ultrastructure of the paratympanic organ in the domestic fowl (Gallus gallus domesticus).

The structure of the paratympanic organ in chickens was investigated by means of the transmission electron microscope. The epithelium lining the lumen of the paratympanic organ consists of sensory and non-sensory components. The sensory epithelium is composed of supporting and hair cells. The hair cells are similar to the type II receptor cells present in the neuroepithelia of the vestibule and of the lateral line organs. The afferent synapses at the bases of the hair cells are also described. The non-sensory epithelium is made up of cells with a clear cytoplasm and arranged in a single layer. It also contains dark, flattened cells which sometimes possess motile cilia. Special emphasis is given to the fact that the results agree with Vitali's theory that the paratympanic organ and the lateral line organs are homologous. It is concluded, therefore, that present knowledge about this structure is not yet sufficient to allow a definitive functional interpretation.

[The ultrastructure of the paratympanic organ (Vitali) in Gallus domesticus: preliminary studies]. / L'ultrastruttura dell'organo paratimpanico (Vitali) in Gallus domesticus: indagini preliminari.

The sensory epithelium of the paratypanic organ (Vitali) was studied by means of the electron microscope. Two kinds of cells are present. One type extends from the basement membrane to the surface of the epithelium; their nuclei are arranged close to the connective tissue and are surrounded by a pale cytoplasm. The distal part of these cells, which are denser and richer in organelles, possess microvilli. The cells of the second type are located above the basement membrane and are found between the upper parts of the cells of the first type. Their cytoplasm is rich in small round vesicles, free ribosomes and cisternae of rough endoplasmic reticulum are present especially in the infranuclear zone. The apical part contains a Golgi apparatus lysosomes and multive sicular bodies. At the apex each cell possesses a cuticular plate numerous stereocilia and one kinocilium. The stereocilia become increasingly longer from one side of the cell surface to the other and the kinocilium is situated on the side where the stereocilia are longest. Nervous fibers are present in the epithelium and are in close contact with the cells of the second type. The cells we have described are remarkably similar to the supporting and hair cells of the vestibular sensory epithelium.

Binding of monofluorophosphate to alpha2-macroglobulin and C3.

After administering an oral dose of monofluorophosphate (MFP) to human beings or rats, a fraction of the drug appears in plasma that is bound to proteins, establishing a previously undetected compartment of nondiffusible fluoride. This article documents experiments performed in vitro, describing the binding of MFP to two plasma globulins: alpha2-macroglobulin and C3 (a beta-globulin). MFP binds irreversibly to these proteins through a stable bond. MFP binds to purified alpha2-macroglobulin or to C3 with a molar ratio MFP: protein close to unity. MFP binding reduces significantly the biological activity of these proteins, which share in common a macrocyclic 4-residue ring thiolactone (Cys-Gly-Glu-Glu). The binding site of MFP is as yet unknown. Protein-bound MFP appeared in the plasma of volunteers during the 5-7 hours following intake. Peak concentration of protein-bound MFP and maximal reduction of alpha2-macroglobulin activity was observed 2 hours after intake. Clearance of protein-bound MFP coincided with the return of alpha2-macroglobulin to basal levels.

Influence of environmental conditions on hyphal morphology in pellets of Aspergillus niger: role of beta-N-acetyl-D-glucosaminidase.

The influence of modifications of the environmental conditions of growth on beta-N-acetyl-D-glucosaminidase (EC 3.2.1.30) activity and on hyphal morphological patterns in pellets of Aspergillus niger was studied. It was found that changes in the degree of branching and, to a lesser extent, in the number of bulbous cells were directly related to the activity of the enzyme. Nevertheless, since beta-N-acetyl-D-glucosaminidase is not the only enzyme involved in the lytic potential of the fungus, these findings do not exclude the possibility that other enzymes may be involved.

Determination of copper, zinc, selenium, lead and cadmium in potatoes (Solanum tuberosum L.) using potentiometric stripping methods.

Potentiometric stripping analysis was used to determine simultaneously the content of zinc(II), cadmium(II), lead(II) and copper(II) in potatoes, whereas the concentration of selenium was determined by cathodic stripping potentiometric analysis. Metal cations were extracted from potatoes by hydrogen peroxide/hydrochloric acid treatments. The relative standard deviation of the methods ranged from 2.3 to 4.1% and the detection limits were lower than 2.5 microg kg(-1). The results obtained with the proposed methods were compared with those obtained with graphite furnace atomic absorption spectroscopy, a common method for determining metals. The results of the two methods agreed to within 6.1%. Twelve samples of yellow flesh potatoes from different cultivars were analysed. Of all the metals determined, Cu and Zn were the most abundant with concentrations between 0.5 and 4.6 mg kg(-1). Selenium was only found in three samples in very low amounts (<0.1 mg kg(-1)), whilst Pb and Cd concentrations were in the range 0.01-0.27 mg kg(-1).

Purification and characterization of a thermostable and highly specific beta-N-acetyl-D-glucosaminidase from Aspergillus niger 419.

After a 10.5-fold purification, beta-N-acetyl-D-glucosaminidase (EC 3.2.1.52) produced by Aspergillus niger 419, showed the following main characteristics: maximum activity at 65 degrees C, pH 4.5; K(m) and kcat using p-nitrophenyl-N-acetyl-beta-D-glucosaminide as substrate, 0.2 mM and 0.93 x 10(4) min-1, respectively; Ea, 30.5 kJ/mol; molecular mass, 131,000 Da; pI 4.4. The activity after heating for 15 min at 70, 75 and 80 degrees C was 70, 28 and 13% of that found at 65 degrees C, respectively. The enzyme was active in reaction mixtures containing glycerol, ethanol, methanol, propan-2-ol, acetone or dioxan. The presence of Sr2+ or Ca2+ enhanced the activity, while it was inhibited by Cu2+ and Fe3+. The enzyme was highly specific for p-nitrophenyl N-acetyl-beta-D-glucosaminide and no activity was found when p-nitrophenyl derivatives of N-acetyl-beta-D-galactosaminide, beta-D-galactopyranoside and beta-D-N,N'-diacetylchitobiose were tested as substrates. Due to its thermostability, specificity and resistance to different organic solvents, the enzyme might be a potentially useful tool for the analysis and production of oligosaccharides.