PubMed Health⌕ Search

Biomedical subjects

B Ferrari

Publications and source records attributed to B Ferrari.

At least 37 records · Page 2Linked to original sources
PubMed1988

Malaria invasion of human erythrocytes. Synthesis of peptides relevant to glycophorin A and evaluation of their inhibitory properties.

The objective of this study was to determine whether a nonglycosylated portion of glycophorin A (GPA), the main erythrocyte membrane glycoprotein, was involved in the process of invasion of red blood cells (RBC) by merozoites of Plasmodium falciparum, a parasite responsible for the most severe form of malaria. A series of peptides covering the sequence 55-76 situated upstream from the intramembraneous hydrophobic region of GPA was synthesized by an active ester coupling strategy and assessed for invasion-blocking capacity by using an in vitro assay system. Tests showed peptide 65-69, Ala-His-His-Phe-Ser, to be a good inhibitor of the invasion of RBC. Results presented here provide a confirmation of the existence of parasite binding sites on the peptide domain of GPA. Furthermore, comparison of inhibitory activity with peptide composition allowed us to rule out any contribution of a toxic parameter related to hydrophobicity as reported earlier.

Animals↗
PubMed1987

Pore formation by Staphylococcus aureus alpha-toxin in lipid bilayers. Dependence upon temperature and toxin concentration.

Staphylococcus aureus alpha-toxin forms ionic channels of large size in lipid bilayer membranes. We have developed two methods for studying the mechanism of pore formation. One is based on measurement of the ionic current flowing through a planar lipid membrane after exposure to the toxin; the other is based on measuring the release of the fluorescent complex Tb-Dipicolinic acid from large unilamellar vesicles under similar conditions. Both methods indicate that the pore formation process is complex, showing an initial delay followed by non-linear kinetics. The power dependence of the pore formation rate on the toxin concentration in planar bilayers indicates that an aggregation mechanism underlies the channel assembly. Arrhenius plots, obtained with both techniques, show no deviation from linearity up to 50 degrees C and the derived activation energies are found to be comparable to those for the binding and the lysis of rabbit erythrocytes by the same toxin. The temperature dependence of the conductance induced in planar bilayers by a large number of toxin channels indicates that the pores are filled with aqueous solution. The analysis of single conductance events shows that a heterogeneous population of pores exist and that smaller channels are preferred at low temperature. We attribute this heterogeneity to the existence of pores resulting from the aggregation of different numbers of monomers.

Bacterial Toxins↗
PubMed1986

Blood group antigens: synthesis of Ss antigenic peptides related to human glycophorin B.

The human Ss blood group antigens are located on glycophorin B, a minor human erythrocyte membrane glycoprotein. The structural difference in Ss antigens is determined by a Met/Thr polymorphism at position 29. This report describes the first synthesis of the two peptides carrying the Ss specificities, SS: Asn-Gly-Glu-Met-Gly-Gln-Leu-Val and ss: Asn-Gly-Glu-Thr-Gly-Gln-Leu-Val.

Amino Acid Sequence↗
PubMed1986

Trapeziometacarpal total joint replacement using the Steffee prosthesis.

The first forty-five Steffee trapeziometacarpal total joint replacements that were used to treat severe trapeziometacarpal arthritis in thirty-eight patients were analyzed retrospectively. The length of follow-up ranged from two through six and one-half years. Forty-two of the arthroplasties resulted in relief of pain, and the restoration of strength and motion was highly satisfactory. Although radiographs showed a high incidence of asymptomatic radiolucent lines at the bone-cement interface of the trapezial component, only three patients had symptomatic loosening. We concluded that trapeziometacarpal total joint replacement can provide good relief of pain and restore function of the thumb to patients with severe trapeziometacarpal arthritis, although further study is necessary to assess the long-term results of the procedure.

Arthritis, Rheumatoid↗
PubMed1984

Synthesis of the Mg antigenic determinant and peptide analogs related to human glycophorin A.

The Mg antigen is a well known rare mutation of the MN blood group system. The amino-terminal pentapeptide related to human glycophorin AMg, Leu-Ser-Thr-Asn-Glu, as well as pentapeptides representing the peptide backbone of glycophorin AM, AN and AMc and other analogs, were synthesized to serve both as glycosyl transferase acceptors and as artificial antigens. These compounds were obtained by a stepwise peptide coupling strategy in solution.

Amino Acid Sequence↗
PubMed1984

Specificity of anti-Mg antibody--a study with synthetic peptides and glycopeptides.

The specificity of a human anti-Mg antibody has been evaluated by agglutination-inhibition assays using several peptides and glycopeptides structurally related to the N-terminal end of glycophorin A, which were obtained by chemical synthesis. We have shown that the anti-Mg antibody is strongly inhibited by pentapeptides containing a leucine residue at their N-terminal end. Glycosylations of these peptides at positions 2, 3 and 4 by N-acetylgalactosamine and/or galactose-beta 1-3-N-acetylgalactosamine units abolish the biological activity, as well as the masking of the leucine residue by addition of N-acetylglycine. The results demonstrate also that the presence of an asparagine residue at position 4 of the pentapeptides (or glycopeptides) is not a requirement for Mg specificity and suggest that the antibody recognizes primarily a nonglycosylated peptide structure with an N-terminal leucine residue.

Amino Acid Sequence↗
PubMed1983

Blood group antigens: synthesis of TN glycopeptide related to human glycophorin AM.

Three 2-acetamido-2-deoxy-alpha-D-galactopyranose residues attached to Ser2, Thr3 and Thr4 of the amino-terminal portion of glycophorin AM are responsible for the so-called TN blood group specificity. In a continuation of earlier work, this report describes the first chemical synthesis of the triglycosylated pentapeptide H2N-Ser1-Ser2*-Thr3*-Thr4*-Gly5-OH, in which (*) represents the 2-acetamido-2-deoxy-alpha-D-galactopyranosyl residue. This compound constitutes the G1-G5 sequence of the amino-terminal portion of human glycophorin AM, the main erythrocyte membrane glycoprotein. The above compound was obtained by a stepwise peptide coupling strategy alternatively using aminoacids and adequately protected and/or activated O-glycosyl-aminoacids. Since the desired sequence possesses both unglycosylated and glycosylated serine this route was preferred to that in which the glycosylation is carried out on the preformed pentapeptide H2N-Ser-Ser-Thr-Thr-Gly-OH. Carbohydrate residues were introduced into the sequence as 2-azido-2-deoxy-alpha-D-galactopyranosyl-L-serine and L-threonine derivatives. The azido functions were further converted into the corresponding acetamido groups by treatment of the final triglyco-pentapeptide with sodium borohydride in the presence of nickel chloride followed by acetylation.

Amino Acid Sequence↗
PubMed1983

Synthetic TN glycopeptide related to human glycophorin AM. High-field proton and carbon-13 nuclear magnetic resonance study.

Three 2-acetamido-2-deoxy-alpha-D-galactopyranoses attached to Ser2, Thr3 and Thr4 of the amino-terminal portion of glycophorin AM are responsible for the so-called TN blood group specificity. The corresponding glycopeptide H2N-Ser-Ser*-Thr*-Gly-OH obtained by a stepwise peptide coupling strategy was submitted to a detailed high-field nuclear magnetic resonance (n.m.r.) analysis. 13C-n.m.r. spectrum confirms the validity of previous assignments made on M sialo and asialoglycopeptides obtained by specific degradation of human glycophorin AM. In addition, the 400 MHz 1H-n.m.r. spectrum allowed most of the proton resonances to be assigned. A careful examination of the chemical shifts and coupling constants revealed some interesting features of the conformational properties of the GalNAc-Ser and GalNAc-Thr linkage as well as of the rotational isomerism of Thr and Ser side-chains. The data give conclusive evidence that high-field n.m.r. spectroscopy can be successfully used to gain structural and dynamic information on rather sophisticated glycopeptides.

Blood Group Antigens↗
PubMed1982

[Trial of a delivery chair in a Parma obstetrics and gynecology clinic].

We have carried out the experiment about the use of "obstetric chairs" on 31 women in labour. There were no obstetric complications for any woman. In all cases the delivery was spontaneous and the patients appreciated the new of delivery very much. The fetus did not show any complication either during the labour or during the alter-birth period. All cases showed a high Apgar - score. The fetal heart rate monitoring didn't record any FHR changes. The midwives didn't point out any difficulty about the delivery management. These results encourage, to continue this experience.

Adolescent↗
PubMed1979

[Down syndrome: cardiotocographic alterations (author's transl)].

The Authors describe the results of a study on the cardiotocographic tracings during labour of pregnant women, whose fetuses were affected by Down syndrome. The high incidence of cardiotocographic alterations in these fetuses does not seem to be in relation with congenital cardiac disease.

Adult↗
PubMed1979

[Concentrations of polyamines in maternal and umbilical-cord blood and in the amniotic fluid during normal human pregnancy and in feto-placental insufficiency].

Blood maternal polyamines during normal pregnancy exhibit an important augmentation around the 10th and the 34th-38th week, and a minor increase between the 20th-25th week of pregnancy. These peaks coincide with extremely important metabolic events in the feto-placental unit such as maximal growth rate in the placenta and fetus, respectively. The levels of polyamines measured from the 38th to 41th week in the blood of the umbilical cord are higher than in the blood of the mother. Putrescine, spermidine and spermine are not detectable when measured in the non-hydrolized amniotic fluid during normal pregnancy, instead a band with a lower Rf than spermine is present. In case of feto-placental insufficiency polyamine concentration in maternal blood are well below the normal values, from the 34th to 38th week of pregnancy. Such a behaviour appears for umbilical cord blood at the 38th and 39th week. Also the unknown polyamine of the amniotic fluid undergoes evident modification in feto-placental insufficiency. These results show that blood polyamines of the mother are probably of fetal origin, and that modified pattern of maternal polyamines may indicate an insufficient body growth of the fetus.

Adult↗