PubMed Health⌕ Search

Biomedical subjects

V Casal

Publications and source records attributed to V Casal.

8 recordsLinked to original sources
PubMed1999

Effects of high pressure and heat treatment on the mineral balance of goats' milk.

Changes in the distribution of minerals in skim goats' milk by high pressure (400 MPa) and/or heat (85 degrees C for 30 min) treatment have been studied. Heat treatment caused reduced solubility of the calcium, magnesium and phosphorus, and this increased with the severity of heating. In contrast, high pressure released different levels of micellar elements into the soluble phase without causing appreciable changes in pH or ionic calcium concentration. The levels of soluble salts returned to their original values when the heated samples were subjected to high pressure. However, heating pressurized milk resulted in concentrations of soluble minerals that were lower than in control milks, and close to values found in heated milks. The salt balance in goats' milk was less affected by high pressure treatment at 75 degrees C than was that of cows' milk. These results are discussed in relation to the effects of high pressure and heat treatment on mineral equilibrium and micellar structure.

Animals↗
PubMed1996

Proteolytic activity of lactobacilli in a model goats' milk curd system.

Mesophyllic lactobacilli cultures propagated in MRS broth were inoculated in goats' milk curd slurries and incubated at 30 degrees C for 10 d. The micro-organisms tested were Lactobacillus casei subsp. casei IFPL 731 and IFPL 99, and Lactobacillus plantarum IFPL 3. Whole cells, cell-free extracts and cell lysates were evaluated for acceleration of proteolysis in the curd slurries. Conversion of water-soluble nitrogen to non-protein nitrogen and amino acid nitrogen, reverse phase-HPLC peak areas and ratio of hydrophobic to hydrophilic peptides, were all affected by the type of inoculum used as well as the strain under study. The results suggest that the accelerated-ripening model system developed, containing cell lysates, may be suitable as a good and rapid indicator of the contribution of the strains to proteolysis during cheese ripening.

Amino Acids↗
PubMed1995

Evaluation of solid-phase extraction procedures in peptide analysis.

Solid-phase extraction (SPE) procedures for peptide isolation and fractionation, based on non-polar and ionic interactions, were evaluated using small synthetic peptides and casein enzymatic hydrolysates. SPE based on hydrophobic phases is a useful, efficient and rapid procedure for peptide extraction and concentration. It allows a successful peptide fractionation using eluents that contain an increasing content of acetonitrile in the presence of trifluoroacetic acid. Differences regarding selectivity are observed between sorbents. Non-polar interaction with C18 sorbents is adequate for the isolation of very polar and hydrophobic peptides. CN sorbents are only adequate for very hydrophobic peptides. PH, CH, C8 and C2 sorbents are useful for isolating and fractionating hydrophobic and very non-polar peptides, but generally not for very polar peptides. Ionic solid-phase extraction using Accell Plus cartridges of QMA (quaternary methylammonium) and CM (carboxymethyl) are very useful for the fractionation of peptide mixtures into basic, acidic and neutral pools of peptides. It can be concluded that SPE using these procedures is a useful tool for the isolation and fractionation of peptides from biological and food samples.

Amino Acid Sequence↗
PubMed1994

Reversed-phase HPLC analysis of peptides in standard and dairy samples using on-line absorbance and post-column OPA-fluorescence detection.

Absorbance and post-column o-phthalaldehyde (OPA)-fluorescent detection were used to analyse standard and dairy peptides following reverse-phase HPLC. Using both detection systems on-line provides additional information on the presence of peptides in dairy products. The detection response depends on the amino acid composition of the peptide involved. Among the peptides used, glutathione, lysine-containing peptides and peptides with glycine as the N-terminal residue give the highest fluorescence after the OPA post-column reaction. Absorbance is more sensitive than fluorescence for peptides with aromatic amino acids. Different parameters, such as the flow rate of OPA, the amount of mercaptoethanol in the OPA reagent and the temperature of reaction, substantially influence the fluorescent response of peptides. The interest of using on-line absorbance and fluorescence detection is highlighted by analysing peptides from skim milk and from a tryptic hydrolysate.

Amino Acid Sequence↗
PubMed1994

[Terminal ileitis due to cryptosporidium and cytomegalovirus in a patient with AIDS].

Terminal patients with infection by the Human Immunodeficiency Virus (HIV), gastrointestinal affection is frequently observed, caused by many etiological agents. However, the affection of the terminal ileon is and generally associated to cytomegalovirus (CMV), intracellular Mycobacterium avium (IMA) and Mycobacterium tuberculosis. We present a patient diagnosed of AIDS with clinical signs of chronic diarrhea secondary to terminal ileitis by Cryptosporidium and CMV. We discuss the radiological and hystological findings and the potential pathogenic synergism.

AIDS-Related Opportunistic Infections↗