Biomedical subjects

M Mecozzi

Publications and source records attributed to M Mecozzi.

9 recordsLinked to original sources

PubMed2005

Exo-enzymatic activities and dissolved organic pools in relation with mucilage development in the Northern Adriatic Sea.

We tested the hypothesis that the appearance of mucilage in the Northern Adriatic Sea was related with the accumulation of dissolved organic compounds released by intensive enzymatic activities and not utilized as direct substrate for microbial growth. To do this enzymatic activities and dissolved organic and inorganic pools in periods characterized by the presence of mucilage and in the same seasons but in absence of mucilage were compared. Extracellular enzymatic activities (aminopeptidase, beta-glucosidase and alkaline phosphatase), nutrient pool concentrations (total dissolved nitrogen, dissolved organic nitrogen, total dissolved phosphorus, dissolved organic phosphorus) and the biochemical composition of particulate and dissolved organic matter (in terms of proteins and carbohydrates) were determined on a monthly basis over a period of 3 years. Aminopeptidase and alkaline phosphatase activities displayed higher values in springs preceding the appearance of mucilage than in spring when no mucilage was observed. Beta-Glucosidase activity showed significantly higher values in summer periods characterized by the massive production of mucilage than in summers without mucilage events. The months preceding mucilage events were also characterized by an increase of the alkaline phosphatase to aminopeptidase activity ratio and by a significant accumulation of dissolved proteins. These findings, together with the significant increase of the DON/DOP ratio, suggest that mucilage formation is favoured by the deficiency of organic P. The present study provides compelling evidences that mucilage formation is favoured by the unbalance between organic matter mobilization by enzymatic activities and the accumulation of labile dissolved organic-N compounds.

Alkaline Phosphatase↗

PubMed2002

Ultrasound extraction and thin layer chromatography-flame ionization detection analysis of the lipid fraction in marine mucilage samples.

This paper reports an analytical procedure based on ultrasound to extract lipids in marine mucilage samples. The experimental conditions of the ultrasound procedure (solvent and time) were identified by a FT-IR study performed on different standard samples of lipids and of a standard humic sample, before and after the sonication treatment. This study showed that diethyl ether was a more suitable solvent than methanol for the ultrasonic extraction of lipids from environmental samples because it allowed to minimize the possible oxidative modifications of lipids due to the acoustic cavitation phenomena. The optimized conditions were applied to the extraction of total lipid amount in marine mucilage samples and TLC-flame ionization detection analysis was used to identify the relevant lipid sub-fractions present in samples.

Chromatography, Thin Layer↗

PubMed2002

An ultrasound assisted extraction of the available humic substance from marine sediments.

In this paper an ultrasound assisted procedure for the extraction of the bio-available fraction of humic substance in marine sediments is described. The proposed method is based on a preliminary 24 h 8 M HCl treatment already proposed in a previous paper [M. Mecozzi, E. Pietrantonio, M. Amici, Fres. Environ. Bull. 7 (1998) 605], followed by consecutive extractions by 0.5 M NaOH coupling to an ultrasonic treatment. The main advantages of the ultrasound procedure are the reduced times of extraction which take 30 min in contrast to the 24 h required by shaking method and the possibility to perform also the quantitative estimation of the extractable fraction of humic substance present in marine samples.

Carbohydrates↗

PubMed2001

Characterization of mucilage aggregates in Adriatic and Tyrrhenian Sea: structure similarities between mucilage samples and the insoluble fractions of marine humic substance.

The appearance of gelatinous aggregates called mucilages causes serious damages to tourism and fishery industries of the Adriatic Sea. So, many studies have been planned and some of them are still in progress to clarify the origin and causes of the phenomenon. The scientific research has showed that mucilages are produced by several marine organisms when peculiar climatic and trophic conditions occur. Moreover, as far as the mucilage composition is concerned, although it is well known that polysaccharides give a high contribution, knowledge of the structural characteristics of mucilages and their relationship with the natural organic matter of the marine environment has not been clarified yet. In this paper a study on the characterization of the marine mucilage samples collected in the Adriatic and Tyrrhenian Seas is described. The study was performed by spectroscopic (infrared and colorimetric) techniques, and elemental analysis. The results showed that mucilage samples have chemical and structural similarities with the insoluble fraction of the marine humic substance (humin). According to experimental evidences it is possible to establish the relationship between mucilages and the dissolved organic matter (DOM) in the marine environment in order to identify the most likely pathways of mucilage formation.

Adhesives↗

PubMed2001

Distribution of chlorinated organic pollutants in harbor sediments of Livorno (Italy): a multivariate approach to evaluate dredging sediments.

Dredging is a very important procedure for harbor management. In Italy the guidelines for the offshore dumping of dredged materials are issued by the Ministry of Environment. They described a few steps of dredging activities, such as the sampling strategy, but do not deal with limits or guide-values for the chemical, physical and biological composition of the resulting sediments. The quality of dredged materials is mainly dependent on the presence of inorganic and organic pollutants. In particular, polychlorinated biphenyls (PCBs) and organo-chlorinated pesticides are seen as a high priority in marine environment by international organizations because of their persistence, toxicity and bioaccumulation capacity. In this article the presence of some PCBs and organo-chlorinated pesticides in sediment samples collected from the harbor of Livorno (Northern Tyrrhenian Sea) was investigated. The concentration of HCHs, Aldrin, Chlordanes, DDEs, DDTs, and PCBs in 12 representative sites ranged between <1 microg kg(-1) and 95, 19, 32, 35, 107, and 111 microg kg(-1), respectively. The application of univariate and multivariate statistical techniques, such as linear regression analysis and principal component analysis, to the experimental data showed a different distribution of PCBs in the two sediment layers. On the contrary, the vertical distribution of the other investigated pollutants was more homogeneous and affected by random variability. The multivariate approach was an important tool to establish more rational criteria for the management of dredged materials.

Conservation of Natural Resources↗

PubMed2001

Determination of carbonate in marine solid samples by FTIR-ATR spectroscopy.

A method for detecting carbonate in marine solid samples (sediments, corals) by Fourier transform infrared spectroscopy (FTIR) coupled to the total attenuated reflectance (ATR) technique is described. Compared to other techniques, the proposed method is not based on the measurement of CO2 evolved by combustion or acidification of the sample, but on the direct measurement of carbonate present in the sample. For this reason, the method by FTIR-ATR spectroscopy does not require any chemical pre-treatment. The proposed method allows determination of carbonate in the range 6-100% (w/w) as Na2CO3 and gives comparable results with the determination of inorganic carbon by elemental analysis.

Animals↗

PubMed2000

Computer assisted determination of ATP in environmental and food samples by bioluminescent assay: comparison of algorithms.

When the bioluminescent assay (BLA) for the determination of adenosine triphosphate (ATP) in environmental and food samples is performed by conventional photometers, a computing procedure is necessary to exclude the mixing time of reagents from the global time of the reaction because it produces a poor analytical precision [M. Mecozzi, A. Amici, G. Visco, Fres. J. Anal. Chem. 357 (1997) 747-751]. In this paper three automated procedures for correcting this interference were tested and compared with illustrate their advantages and drawbacks. The three techniques were the robust exponential regression and the outliers detection method (RER), the smoothing technique of Savitzky-Golay (SSG) and the smoothing technique of Kalman Filter (SKF). RER and SSG were found to be more effective than SKF in minimizing the effect of noise produced by the mixing of reagents. In addition, the application of computing procedures such as RER and SSG allow to improve the detection limit in the BLA performed by conventional photometers.

Adenosine Triphosphate↗

PubMed1999

Ultrasound-assisted analysis of total carbohydrates in environmental and food samples.

Analytical methods to determine total carbohydrates in environmental and food samples usually require a preliminary chemical hydrolytic procedure to convert polysaccharides into monosaccharides prior to detection by colorimetric or chromatographic techniques. In this paper, an alternative hydrolytic procedure is presented. The method for hydrolysis of polysaccharides is based on the application of ultrasound at room temperature. The advantages of the method proposed here are reduced time required for analysis (4-5 h) and the improvement of the analytical accuracy due to the absence of the most common reactions of oxidation. The proposed method was applied to the determination of total carbohydrates in several environmental samples (seawater and marine mucilage) and starchy food samples. Results for total carbohydrate obtained using the ultrasound procedure for hydrolysis of samples agreed with those found when applying other published procedures.

Adhesives↗

PubMed1997

A software program based on robust linear regression methods for instrumental calibration in biochemical analysis.

A microcomputer program written in GWBASIC for conventional least squares regression (LS) and robust linear regression methods (RRMs) such as single median (SM) and repeated median (RM) is described. The main advantages of RRMs is the ability to detect outliers which can cause an inaccurate estimation of the analyzed samples. It requires MS DOS PC version 3.3 or higher and at least 256 kbyte of RAM. The joint application of RRMs and residuals analysis by the studentized method (STRM) allows a more precise biochemical analysis.

Biochemistry↗