Search PubMed⌕ Search

Biomedical subjects

S Fadda

Publications and source records attributed to S Fadda.

At least 19 recordsLinked to original sources
PubMed2006

Surface properties and behaviour on abiotic surfaces of Staphylococcus carnosus, a genetically homogeneous species.

This work aimed to characterize the surface properties of Staphylococcus carnosus and the influence of different media on their ability to adhere and grow on industrial supports. As their colonization could be dependant of the strain, the genetic diversity of the strains was studied. The diversity of 13 strains analysed by pulsed-field gel electrophoresis revealed that the S. carnosus strains formed a homogeneous genetic group. Their surface properties, characterized by studying their affinity to solvents, were hydrophilic with a strong negative surface charge. The S. carnosus strain CIT 833 hardly adhered to polytetrafluoroethylene (PTFE) and stainless steel chips. Tryptic soy broth (TSB) was the most favourable medium for growth on stainless steel support while TSB/NaCl was better for growth on PTFE. Scanning electron microscopy (sem) showed that this strain weakly colonized both supports and did not form cell aggregates. Indeed, the strain did not synthesize polysaccharides. These results showed that S. carnosus adhered on different abiotic surfaces which are used in food factories but was not able to accumulate on these surfaces. The inability of S. carnosus to form biofilm could explain why S. carnosus is rarely isolated in meat processing environment.

Bacterial Adhesion↗
PubMed2002

Decarboxylase activity involved in methyl ketone production by Staphylococcus carnosus 833, a strain used in sausage fermentation.

Staphylococcus carnosus strain 833, inoculated into sausage, increased the levels of methyl ketones which contributed to the cured aroma. These ketones were predicted to arise from incomplete beta-oxidation followed by a decarboxylation. To check this hypothesis, we measured the beta-decarboxylase activity in resting cells of S. carnosus grown in complex or in synthetic medium, using as substrate a beta-ketoacid, which can be an intermediate of the beta-oxidation pathway. This activity was present throughout the growth period. The enzyme appeared to be constitutive because no induction was observed. High aeration, a pH of 5 and the presence of nitrate promoted the production of methyl ketones.

Carboxy-Lyases↗
PubMed2001

Effect of curing conditions and Lactobacillus casei CRL705 on the hydrolysis of meat proteins.

AIMS: The effect of the common curing conditions used during the manufacture of dry fermented sausage on the proteolytic activity of Lactobacillus casei CRL705 against meat proteins was investigated. METHODS AND RESULTS: Hydrolysis of pork muscle sarcoplasmic and myofibrillar proteins was evaluated by SDS-PAGE and reverse phase-HPLC analysis. Ascorbic acid exerted a stimulatory effect on both sarcoplasmic and myofibrillar protein breakdown by Lact. casei CRL705 with the release of hydrophilic peptides and free amino acids, while NaCl and NaNO2 mainly stimulated myofibrillar degradation. CONCLUSION: Even when processing temperature (25 degrees C) did not positively affect bacterial protein hydrolysis, the presence of curing salts accounted for a remarkable increase in the non-volatile components that constitute taste-active compounds that strongly influence the final flavour of the product. SIGNIFICANCE AND IMPACT OF THE STUDY: To predict the suitability of Lact. casei CRL705 and its proteolytic enzymes as a starter culture for the dry processing of dry fermented sausages.

Amino Acids↗
PubMed1999

Hydrolysis of muscle myofibrillar proteins by Lactobacillus curvatus and Lactobacillus sake.

Proteolytic enzyme activities of whole cells and cell free extracts (CFE) of Lactobacillus curvatus CECT 904 and Lactobacillus sake CECT 4808 were characterised using synthetic chromogenic compounds and myofibrillar proteins as substrates. The hydrolytic action was monitored by SDS-PAGE and reverse phase-HPLC analyses. The CFE of L. sake partially contributed, together with muscle enzymes, to the initial hydrolysis of myofibrillar proteins. Whole-cells of both L. curvatus and L. sake generated peptides considered important for cured-meat taste. The peptide mapping, resulting from the action on the substrates assayed, revealed a profile of extra and intracellular enzymes. Both strains expressed strong amino acid metabolism.

Aminopeptidases↗
PubMed1999

Hydrolytic action of Lactobacillus casei CRL 705 on pork muscle sarcoplasmic and myofibrillar proteins.

Lactobacillus casei CRL 705 was screened, among other meat isolates, for its proteinase and aminopeptidase activities toward synthetic substrates and, according to that, selected for specific assays on muscle proteins. The hydrolytic effects of whole cells, cell free extracts (CFE), and the combination of both on muscle sarcoplasmic and myofibrillar protein extracts was evaluated by SDS-PAGE and reverse phase HPLC analyses. The proteinase activity of whole cells caused the degradation of a great number of sarcoplasmic protein bands. A partial hydrolysis was also associated with CFE that when combined with whole cells showed an important additional degradation. Peptide profiles from sarcoplasmic protein extracts were greatly modified regardless of the addition of whole cells or CFE, although their combination intensified these changes. The generation of free amino acids was remarkable when whole cells and CFE were incorporated together to sarcoplasmic protein extracts.

Aminopeptidases↗
PubMed1999

Hydrolysis of pork muscle sarcoplasmic proteins by lactobacillus curvatus and lactobacillus sake.

Lactobacillus curvatus CECT 904 and Lactobacillus sake CECT 4808 were selected on the basis of their proteolytic activities against synthetic substrates. Further, the effects of whole cells, cell extracts, and a combination of both enzymatic sources on muscle sarcoplasmic proteins were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reverse-phase high-performance liquid chromatography analyses. Strains of both species displayed proteinase activities on five sarcoplasmic proteins. The inoculation of whole cells caused a degradation of peptides, whereas the addition of cell extracts resulted in the generation of both hydrophilic and hydrophobic peptides. This phenomenon was remarkably more pronounced when L. curvatus was involved. Whole cells also consumed a great amount of free amino acids, while the addition of intracellular enzymes contributed to their generation. L. sake accounted for a greater release of free amino acids. In general, cell viability and also proteolytic events were promoted when cell suspensions were provided with cell extracts as an extra source of enzymes.

Journal Article↗
PubMed1999

Characterization of muscle sarcoplasmic and myofibrillar protein hydrolysis caused by Lactobacillus plantarum.

Strains of Lactobacillus plantarum originally isolated from sausages were screened for proteinase and aminopeptidase activities toward synthetic substrates; on the basis of that screening, L. plantarum CRL 681 was selected for further assays on muscle proteins. The activities of whole cells, cell extracts (CE), and a combination of both on sarcoplasmic and myofibrillar protein extracts were determined by protein, peptide, and free-amino-acid analyses. Proteinase from whole cells initiated the hydrolysis of sarcoplasmic proteins. The addition of CE intensified the proteolysis. Whole cells generated hydrophilic peptides from both sarcoplasmic and myofibrillar proteins. Other peptides of a hydrophobic nature resulted from the combination of whole cells and CE. The action of both enzymatic sources on myofibrillar proteins caused maximal increases in lysine, arginine, and leucine, while the action of those on sarcoplasmic proteins mainly released alanine. In general, pronounced hydrolysis of muscle proteins required enzyme activities from whole cells in addition to those supplied by CE.

Amino Acids↗
PubMed1996

Control of Listeria monocytogenes in ground beef by 'Lactocin 705', a bacteriocin produced by Lactobacillus casei CRL 705).

The effectiveness of Lactobacillus casei CRL 705 as well as that of Lactocin 705, the associated bacteriocin produced, in reducing population levels and growth of Listeria monocytogenes in sterile and non-sterile ground beef was studied. Predetermined numbers of L. monocytogenes and concentrations of Lactocin 705 were added to the meat slurries. Listeria in the bacteriocin-treated and control samples during incubation at 20 degrees C were enumerated as CFU on Bacto blood agar base. Results indicated that reduction in numbers of Listeria was largest with high levels of Lactocin 705 and few initial cell numbers of the pathogen present in the meat slurry. However, when the producer strain was added to the slurry, no significant inhibition was detected. Furthermore, inhibition by listeria was shown to be greater when meat slurries were heat-treated.

Animals↗
PubMed1991

A common disinfectant used in condom processing inhibits endonuclease digestion of sperm DNA.

DNA recovered from a condom found at a crime scene appeared undigestible with restriction enzymes, preventing characterization by Southern blot and polymorphic probe hybridization. Several chemical substances used in the processing and treatment of condoms were tested for inhibitory action of restriction enzymes. In particular dibenzalkonium chloride appeared to promote enzyme inhibition at very low concentrations. The effectiveness of treatments to restore cleavage of sample DNA in the presence of such contaminants is discussed.

Benzalkonium Compounds↗
PubMed1985

Definitive localization of Becker muscular dystrophy in Xp by linkage to a cluster of DNA polymorphisms (DXS43 and DXS9).

A study of linkage between Becker muscular dystrophy and four X chromosome-specific DNA polymorphisms in 17 kindreds has indicated that this gene is located in Xp, as already anticipated by single pedigree analysis. In particular the DXS43 and DXS9 loci, identified by probes D2 and RC8, respectively, are closely linked to each other and are both located at approximately 15 cM from the Becker locus. These linkage data, together with the previously established linkage between Becker and the DXS7 locus identified by probe L 1.28, indicate that the Becker gene is located in the same region where Duchenne has been mapped and also yield information about relative genetic distances among different DNA polymorphisms of the X chromosome.

Alleles↗
PubMed1985

Mapping of X-linked Becker muscular dystrophy through crossovers identified by DNA polymorphisms and by haplotype characterization in somatic cell hybrids.

The analysis of 10 X-linked DNA polymorphisms (five mapping on the short arm and five on the long arm) in two Becker muscular dystrophy pedigrees has been used to localize this gene in the known sequence of DNA polymorphic markers on the X chromosome. In the first pedigree, the carrier mother, whose phase for Becker and for five informative polymorphisms is known, has transmitted a double recombinant X chromosome to one of her two affected sons. The discordance between these two affected brothers for four of the five informative polymorphisms indicates that the Becker gene is located between RC8 or D2 on one side and pDP34 on the other. In the second pedigree, where the maternal grandfather is dead and two maternal first cousins are affected, the phase of DNA polymorphic alleles has been identified in somatic cell hybrids resulting from the fusion of hamster fibroblasts with lymphocytes of the mothers and aunt of the patients. The discordance between the two first cousins for two of the four informative DNA polymorphisms is best explained by the occurrence of a single recombination in the X chromosome carried by one of them. This result further restricts the localization of the Becker gene to a region of the short arm delimited by B24 and L 1.28. Regional and fine gene mapping through the approach described in this paper should become useful in the future for X-linked as well as for autosomal genes.

Animals↗
PubMed1983

Incidence of Friedreich ataxia in Italy estimated from consanguineous marriages.

The frequency of consanguineous marriages up to second-cousin degree has been carefully established in the past for each of the 95 Italian provinces using the Archive of about 500,000 dispensations given by the Catholic church for such marriages over a 55-year period. It has therefore been possible to compare the frequency of consanguineous marriages observed among 83 couples of parents of Friedreich patients with the frequency of consanguineous marriages of the same degree in the different Italian provinces during the same years. From these data, an estimate of the incidence of the disease has been obtained for the whole nation (between 1/22,000 and 1/25,000). In Southern Italy, where 16 out of the 18 consanguineous marriages among Friedreich parents are concentrated, the incidence of the disease is similar (between 1/25,000 and 1/28,000). This study indicates that the Archive of consanguinity existing in Italy allows a reliable comparison of the frequency of consanguineous marriages among parents of patients with that of the general population. The same method can therefore be applied to the study of incidence of other autosomal recessive disorders in Italy.

Adult↗
PubMed1980

Regulation of cyclic AMP levels in human lymphocytes and lymphoblasts by prostaglandins.

The sensitivity of human lymphocytes to prostaglandins was compared to that of two lines of cultured lymphoblasts. It was found that 25 nM PGE1 increased lymphocyte cyclic AMP levels twofold, but had no effect on lymphoblasts. At 2.8 micrometers PGE1 the increase of cyclic AMP in lymphocytes was 14 fold versus a 1-3 fold increase in lymphoblasts. Lymphoblasts maintained a response to 6-keto-PGE1, isoproterenol and histamine similar to that observed in lymphocytes. Thus, it appears that the rapidly proliferating lymphoblasts excape signals inhibiting proliferation by impairing the function of the PGE receptor.

Alprostadil↗
PubMed1980

The effect of 6-keto-prostaglandin E1 on human lymphocyte cAMP levels.

6-keto-PGE1 was capable of increasing cyclic AMP levels of peripheral human blood lymphocytes in a dose and time dependent fashion. The response was maximal after 30 min of incubation at 37 degrees C; 1 microgram per ml of 6-keto-PGE1 elevated cyclic AMP levels 5 fold which compares with a 10 fold increase due to PGE1. Thus 6-keto-PGE1 may play a role as a modulator of lymphocyte function.

Alprostadil↗