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Biomedical subjects

D Romeo

Publications and source records attributed to D Romeo.

At least 55 records · Page 3Linked to original sources
PubMed1987

Modulation of human neutrophil function by C-reactive protein.

Investigation of the effect of C-reactive protein (CRP), an acute-phase reactant, on the functional capacities of human neutrophils was carried out as the basis for elucidating the biological function of C-reactive protein. An initial stimulation at low concentrations, followed by inhibition of superoxide production, and secretion of vitamin-B12-binding protein in the presence of two stimulants, phorbol myristate acetate and concanavalin A, and of neutrophil chemotaxis with increasing concentration of CRP was observed. Correlation between modulation of cell function, at least at relatively high CRP concentrations (greater than 50 micrograms/ml) and an increase in the intracellular level of cAMP is suggested. CRP was also found to enhance neutrophil phagocytosis of particles not containing phosphorylcholine, the native CRP ligand. The proposed role of CRP in neutrophil function is one of regulation and as a negative feedback for potential cytotoxic neutrophil functions.

Bacterial Outer Membrane Proteins↗
PubMed1987

Inactivation of herpes simplex virus by protein components of bovine neutrophil granules.

From an acid extract of granules of bovine neutrophils we isolated fractions of cationic proteins, exhibiting significant anti-herpesvirus activity at concentrations which were devoid of cytotoxicity and of activity against a picornavirus (rhinovirus). The mechanism of action seems to involve a direct neutralization of the virions. Two antiviral peptides with an approximate MW 7500 were purified to homogeneity by reversed phase high-performance liquid chromatography. Proline and arginine accounted for about 43% and 26-27% of their amino acid residues. One of these peptides (IIIa2 beta) had an MIC of 2 microM.

Animals↗
PubMed1987

Successful therapy of Niemann-Pick disease by implantation of human amniotic membrane.

In a patient with a lysosomal storage disorder, not involving the CNS, repeated implantations of human amniotic sheets have proved to provide a successful approach to enzyme replacement therapy. Implantation of pure epithelial cells, separated from the other cell types of the amnion, might markedly improve the procedure, avoiding some risks of host-versus-graft rejection.

Adolescent↗
PubMed1986

C5a fragment of bovine complement. Purification, bioassays, amino-acid sequence and other structural studies.

C5a and des-Arg-C5a have been purified from bovine serum in milligram amounts. The progress of the purification was followed by measuring the chemotactic activity of the complement fragments. The two polypeptides induce activation of neutrophil-oriented locomotion and secretion with very similar dose/response effects. After preparing a rabbit antiserum to bovine C5a/des-Arg-C5a, a competitive enzyme-linked immunosorbent assay (ELISA) was set up for the detection of C5a from 5 ng/mol to 1 microgram/ml. The complete primary structure of bovine C5a, which consists of 74 amino acids, has been determined by sequence analysis of the tryptic peptides, aligned by peptides derived from a chymotryptic digest, and by partially sequencing the intact molecule. Bovine C5a has a sequence homology of 78% and 70% with porcine and human C5a, respectively, reacts with an antiserum to porcine C5a and is recognized by cell surface receptors on human neutrophils. Finally, the secondary structure of bovine C5a was investigated by circular dicroic spectroscopy and predicted from the amino acid sequence. A comparison of the content and distribution of alpha-helical and/or hydropathic regions, suggests that the three-dimensional structure of C5a might be modeled from the known crystal structure of the homologous C3a molecule.

Amino Acid Sequence↗
PubMed1986

Co-activation of protein kinase C and NADPH oxidase in the plasma membrane of neutrophil cytoplasts.

Enucleated, granule-free neutrophil cytoplasts, which in hypotonic media fully release cytosolic components and generate ghosts, have been used to study the cell localization of protein kinase C (PK-C). Treatment of cytoplasts with phorbol myristate acetate, a potent activator of neutrophil functions, triggers translocation of PK-C from the cytosol to the plasma membrane, with an activity recovery of 83 +/- 16%. In the ghost fraction, PK-C catalyzes the phosphorylation of polypeptides with an apparent mol. wt. of 115K, 89K, 79K, 62K, 47K and 19K. From the plasma membrane PK-C can be extracted in an active form by Triton X-100 but not by EGTA. Translocation of PK-C is already evident at 5 sec and plateaus at about 50 sec. Activation of plasmalemmal, O-2 generating NADPH oxidase by the phorbol ester is delayed by about 20 sec with respect to the activation of PK-C. Dose/response experiments show that the pattern of activation of O-2 generation by cytoplasts strictly superimposes with the pattern of PK-C translocation.

Adenosine Triphosphate↗
PubMed1985

Activation of protein kinase C in neutrophil cytoplasts. Localization of protein substrates and possible relationship with stimulus-response coupling.

Treatment of enucleated, granule-free neutrophil cytoplasts with the protein kinase C activator phorbol 12-O-myristate-13-acetate (PMA) causes an increased 32P-incorporation into a variety of polypeptides. Permeabilization of PMA-stimulated, 32P-labeled cytoplasts by 0.01% digitonin fully releases the majority of these phosphorylated proteins. A statistically significant correlation is found between the extent of PMA-induced activation of generation of superoxide anion (O2-) and the phosphorylation of a cytosolic polypeptide with an apparent Mr of 46,000, whose 32P-labeling is also enhanced by the treatment of cytoplasts with 1-oleyl-2-acetylglycerol, the Ca2+ ionophore ionomycin or latex beads. Furthermore, treatment of cytoplasts with the protein kinase C inhibitor trifluoperazine markedly inhibits the 32P-labeling of proteins in the 40 000 Mr range, including the 46 kDa polypeptide, and almost totally abolishes the activation of O2- production by PMA.

Animals↗
PubMed1984

Mobilization of heparan sulfate induced by immunostimulation in a patient with mucopolysaccharidosis IIIA.

Unspecific immunostimulation by bacterial vaccines of a patient with mucopolysaccharidosis IIIA (Sanfilippo A) syndrome induces a marked increase in the urinary excretion of heparan sulfate and of uronate-containing oligosaccharides. This event is presumably linked to an increased vascular permeability and exocytosis of storage material, elicited by mediators of inflammation, as well as to enhanced degradation of stored polymers in activated macrophages and surrounding tissue.

Bacterial Vaccines↗
PubMed1984

Monitoring of cytosolic free Ca2+ in C5a-stimulated neutrophils: loss of receptor-modulated Ca2+ stores and Ca2+ uptake in granule-free cytoplasts.

The cytosolic concentration of free Ca2+ in bovine neutrophils was monitored by using the intracellular Ca2+ indicator quin2, 2-[[2-bis(acetylamino)-5-methylphenoxy]methyl-6-methoxy-8- bis(acetylamino)]quinoline. Neutrophils at rest have a cytosolic Ca2+ concentration of 85 +/- 5 nM, which in 2-4 min increases to 300-400 nM upon interaction with the complement fragment C5a in a concentration range of 35 pM to 1.2 microM. In the same concentration range, C5a also sequentially activates neutrophil directional migration (ED50 less than 0.5 nM), O-2 production (ED50 = 9 nM), and secretion of the contents of specific granules (ED50 = 39 nM). The selective Ca2+ ionophore ionomycin also increases cytosolic Ca2+ concentration above 1 microM under conditions where it stimulates neutrophil functions. Conversely, phorbol 12-myristate 13-acetate markedly activates secretion and O-2 production without modifying the average cytosolic Ca2+ concentration. In the presence of EGTA (Ca2+out approximately equal to 20 nM), with both C5a and ionomycin, cytosolic Ca2+ increases to less than 200 nM, and functional responses are greatly decreased. Nucleus- and granule-free neutrophil cytoplasts accumulate Ca2+ and produce O-2 when exposed to ionomycin but not to C5a. These results and other considerations suggest that (i) activation of neutrophil functions may occur after cytosolic Ca2+ has exceeded the apparent threshold level of 200 nM; (ii) C5a receptor-mediated activation of Ca2+ influx may require cooperation between the neutrophil surface and some cytoplasmic organelle and/or redistribution of the C5a-receptor complexes on the cell surface; and (iii) the phorbol diester stimulates Ca2+-dependent pathways presumably by directly activating other mechanisms such as protein phosphorylation.

Animals↗
PubMed1984

Wide-spectrum antibiotic activity of bovine granulocyte polypeptides.

The antibiotic activity of a polypeptide fraction purified from bovine granulocyte granules was tested against Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Bacillus subtilis, Bacillus stearothermophilus, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, Streptococcus pyogenes, and clinical isolates of Staphylococcus and Enterobacter spp. All of these bacterial species were susceptible to the antibiotic polypeptide(s), with MICs ranging from 3 to 100 micrograms of protein per ml. The antimicrobial activity was resistant to boiling and abolished by proteinase treatment. Saccharomyces cerevisiae and human fibroblasts grew normally in the presence of 100 and 50 micrograms of antibiotic polypeptide(s) per ml, respectively. [3H]thymidine incorporation into bacterial, but not fibroblast, DNA was efficiently and promptly inhibited by the antimicrobial polypeptide preparation. This suggests that its main target is a component of the system, which catalyzes and regulates the biosynthesis of bacterial DNA.

Animals↗
PubMed1983

Neurotensin modulates human neutrophil locomotion and phagocytic capability.

Neurotensin (NT) was found to induce oriented locomotion and augment the phagocytic capability of human blood neutrophils over 10(-11) - 10(-7) M. The tridecapeptide also causes Ca2+ extrusion from neutrophils, very likely as a result of intracellular Ca2+ mobilization. It is suggested that the NT-mediated functional modulation of neutrophils correlates with the capacity of NT to affect the intracellular compartmentalization of Ca2+. Peripheral NT-elicited phenomena such as vasodilation, enhanced vascular compartmentalization of Ca2+. Peripheral NT-elicited phenomena such as vasodilation, enhanced vascular permeability, mast cell degranulation and the enhancement of directional migration and phagocytosis of neutrophils described here, classify NT as a typical mediator of inflammation.

Calcium↗
PubMed1983

Potency of bactericidal proteins purified from the large granules of bovine neutrophils.

The novel population of large granules of bovine neutrophils, which is the cell store of bactericidal activity independent of O2 derivatives, was extracted with an acid medium. Several fractions were resolved from the extract by ion-exchange chromatography (with carboxymethyl-cellulose) and gel filtration (with Sephadex G-50). Some of these fractions contained only a very limited number of major components, as detected by polyacrylamide gel electrophoresis. The purified bactericidal proteins exhibited their activity at 0.1 to 10 micrograms/0.3 ml of assay mixture containing 1 X 10(6) to 2 X 10(6) CFU of Staphylococcus aureus or Escherichia coli in media with physiological concentrations of Na+, K+, Mg2+, and Ca2+. Two fractions, containing polypeptides with apparent molecular weights ranging from 28,000 to less than 12,000, caused rather selective and rapid (5 to 20 min) killing of S. aureus. Their action was accompanied by significant binding to the gram-positive bacteria of some low (less than 12,000)-molecular-weight components. Other Sephadex G-50 fractions, containing the first emerging proteins with relatively high molecular weights, were more active on E. coli than on S. aureus. With the gram-negative bacteria there was a 10-min delay in the onset of bactericidal activity, which thereafter developed very fast. On the basis of the in vitro potency of the large-granule bactericidal proteins, we suggest that even partial discharge of granule content into the phagosomes may supply the phagocytic vacuoles of bovine neutrophils with a very efficient nonoxidative bactericidal system acting on both gram-positive and gram-negative microorganisms.

Animals↗