Biomedical subjects

Hans Meisel

Publications and source records attributed to Hans Meisel.

4 recordsLinked to original sources

PubMed2006

Synthesis of a molecularly imprinted polymer for the selective solid-phase extraction of chloramphenicol from honey.

Solid-phase extraction (SPE) with a molecularly imprinted polymer (MIP) as sorbent has been investigated for the clean-up of the broad-spectrum bacteriostatic antibiotic chloramphenicol (CAP) in honey samples. The MIP was prepared by using methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EDMA) as cross-linker, chloroform as porogen and CAP as template molecule. The binding behaviour of the template CAP on the MIP was evaluated by high-performance liquid chromatography, and then the MIP was applied as a sorbent in SPE to selectively extract CAP from honey. It was shown that recoveries of nearly 100% of a CAP standard solution and up to 94% from spiked honey samples could be obtained after SPE.

Chloramphenicol↗

PubMed2005

Biochemical properties of peptides encrypted in bovine milk proteins.

Milk proteins are precursors of many different biologically active peptides. These peptides are inactive within the protein sequence, requiring enzymatic proteolysis for release of the bioactive fragment from the proteins precursor. It is evident that activated peptides originating from milk proteins should be taken into account as potential modulators of various regulatory processes in the body. Activated peptides are potential modulators of various regulatory processes in the living system: immuno-modulatory peptides stimulate the activities of cells of the immune system and several cytomodulatory peptides inhibit cancer cell growth, antimicrobial peptides kill sensitive microorganisms, angiotensin-I-converting enzyme (ACE)-inhibitory peptides exert an hypotensive effect, opioid peptides are opioid receptor ligands which can modulate absorption processes in the intestinal tract, mineral binding peptides may function as carriers for different minerals, especially calcium, antithrombotic peptides inhibit fibrinogen binding to a specific receptor region on the platelet surface and inhibit aggregation of platelets. Moreover, many milk-derived peptides reveal multifunctional properties, i.e. specific peptide sequences having two or more different biological activities have been reported. Bioactive peptides can interact with target sites (e.g. receptors, enzymes) at the luminal side of the intestinal tract, or they could be absorbed and reach any potential site of action in the system to elicit physiological effects. Bioactive peptides encrypted in bovine milk proteins can be produced on an industrial-scale and are claimed to be health enhancing components for functional foods, nutraceuticals and pharmaceutical preparations that are used to reduce risk of disease or to enhance certain physiological functions.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2004

Multifunctional peptides encrypted in milk proteins.

Many bioactivities of milk are latent in that they are inactive within the protein sequence, requiring enzymatic proteolysis for release of bioactive peptides from milk proteins precursors. Bioactivities of peptides encrypted in major milk proteins are latent until released and activated, e.g. during gastrointestinal digestion or food processing. Bioactive peptides can be produced in vivo following intake of milk proteins, and the proteolytic system of bacterial species used in the production of fermented milk products and cheese can contribute to the liberation of bioactive peptides or precursors thereof. Activated peptides are potential modulators of various regulatory processes in the living system: immunomodulatory peptides stimulate the activities of cells of the immune system and several cytomodulatory peptides inhibit cancer cell growth, antimicrobial peptides kill sensitive microorganisms, angiotensin-I-converting enzyme (ACE)-inhibitory peptides exert an hypotensive effect, opioid peptides are opioid receptor ligands which can modulate absorption processes in the intestinal tract, mineral binding peptides may function as carriers for different minerals, especially calcium. Many milk-derived peptides reveal multifunctional properties, i.e. specific peptide sequences having two or more different biological activities have been reported. Milk protein-derived bioactive peptides are claimed to be health enhancing components that can be used to reduce the risk of disease or to enhance a certain physiological function.

Animals↗

PubMed2002

Cytochemical assessment of phosphopeptides derived from casein as potential ingredients for functional food.

Phosphopeptides derived from casein hydrolysis are suggested to have beneficial effects beyond their mere nutritive value by enhancing availability of dietary minerals, especially calcium, iron and zinc. Apart from a possible positive action the potential may exist for adverse effects that could impose restrictions to their widespread application in functional foods for human nutrition. In the present work, various case-inophosphopeptide (CPP) preparations were assessed using different human cell culture model systems in order to estimate their cytotoxic potential and their influence on epithelial properties and differentiation of human intestinal cells (Caco-2). The general cytotoxic potential of CPPs was tested using the AlphaTox NR assay. Structural and functional differentiation of intestinal Caco-2 cells was determined by measuring transepithelial electrical resistance and activity of brush border associated alkaline phosphatase over an extended cultivation period. No loss in cell viability with respect to membrane integrity could be detected, as uptake and retention of neutral red dye (AlphaTox assay) into HeLa cells was not affected by the presence of CPPs. Cytochemical assays conducted on epithelial cells (Caco-2) showed no disturbance of normal cell development and differentiation with respect to structural as well as functional differentiation markers. As all CPPs tested did not provoke any adverse effects in terms of cytotoxicity and showed no impairment of cell differentiation and monolayer integrity of human intestinal cells, it may be supposed that CPPs do not provoke a cytotoxic response in vivo in the cells assayed in the present study.

Alkaline Phosphatase↗