PubMed Health⌕ Search

Biomedical subjects

J M Piot

Publications and source records attributed to J M Piot.

33 records · Page 2Linked to original sources
PubMed1995

Peptic hemoglobin hydrolysis in an ultrafiltration reactor at pilot plant scale generates opioid peptides.

Two hemorphins, peptides with opioid activity, have been isolated from a pepsin hydrolysate of bovine hemoglobin, by use of gel permeation (GP) and reverse phase (RP) high-performance liquid chromatography (HPLC). Their primary structure and accurate molecular weights, determined by amino acid analysis and fast atom bombardment (FAB) mass spectrometry, were identical to fragments 31-40 (LVV-hemorphin-7) and 32-40 (VV-hemorphin 7) of the beta-chain of bovine hemoglobin. Two other peptides, 34-40 (hemorphin-7) and 34-41 (hemorphin-8) of the beta-chain of bovine hemoglobin, have been synthesized and studied. The opioid potency of these peptides, exhibited by the use of electrically stimulated muscle of isolated guinea pig ileum (GPI), were significant and comparable with some others previously described. Studies of opioid activities and primary structure of hemorphins led us to postulate the important role of arginine and phenylalanine in opioid potency.

Amino Acid Sequence↗
PubMed1995

VV-hemorphin-7 and LVV-hemorphin-7 released during in vitro peptic hemoglobin hydrolysis are morphinomimetic peptides.

Two opioid peptides were generated by in vitro pepsin treatment of bovine hemoglobin. These peptides were identified using a GPI test and purified using HPLC chromatographic techniques. They correspond to fragments 31-40 (LVV-hemorphin-7) and 32-40 (VV-hemorphin-7) of the beta-chain of bovine hemoglobin. Binding experiments strongly confirm that VV-hemorphin-7 and LVV-hemorphin-7 are opioid peptides since they inhibited [3H]naloxone binding to rat brain membranes. Our results indicate that VV-hemorphin-7 and LVV-hemorphin-7 exhibit a lesser potency both in GPI and binding tests. Selectivity and affinity of these purified peptides and synthetic hemorphin-7 for opioid receptors is discussed.

Animals↗
PubMed1995

Isolation from bovine haemoglobin of a peptide that might be used as a potential hydrophobic photosensitizer carrier.

The isolation of a peptic hydrolysate and of a pure peptide from bovine haemoglobin is described. These peptides were used to solubilize an insoluble photosensitizer in order to study their utilization as a carrier for photochemotherapy. Protoporphyrin IX was used as a model of an insoluble photosensitizer. Solubilization of protoporphyrin IX was first performed with the total haemoglobin hydrolysate, then with peptide fractions, and finally with a pure peptide isolated from this fraction by reversed-phase HPLC. The molecular mass and the primary structure of the pure peptide were determined by fast-atom-bombardment and tandem MS (molecular mass 1648 Da). The singlet oxygen quantum yield of the protoporphyrin IX-peptide complex was determined.

Amino Acid Sequence↗
PubMed1994

Photophysical and photobiological activities of a porphyrin peptide fraction derived from haemoglobin.

In a previous study, we described the preparation of a porphyrin peptide hydrolysate from haemoglobin, its isolation and its analysis by high performance liquid chromatography (HPLC) and fast atom bombardment (FAB) mass spectrometry. The purpose of the present paper is to test the photosensitizing activity of this fraction. We determined the singlet oxygen quantum yield (phi delta) in order to quantify the efficiency of the porphyrin peptide fraction. The quantum yield is about phi(1O2)=0.06. An analysis of the phototoxic effect on tumour cells in culture was performed and compared with haematoporphyrin derivative (HpD), the only photosensitizer in clinical use at present. The phototoxicity of the porphyrin peptide fraction is weaker than that of HpD. However, for a porphyrin dose of 50 micrograms ml-1, the difference in phototoxicity is low, and in the absence of irradiation porphyrin peptides are less toxic than HpD. These results suggest that porphyrin peptides could be potent photosensitizers; moreover, they are of great interest since they allow the solubilization of hydrophobic porphyrins and could be applied in the future as insoluble photosensitizer carriers.

Cell Line↗
PubMed1993

Stabilizing effect of water/alcohol solvents towards autoxidation of human haemoglobin.

The stabilization of haemoglobin (Hb) in water/alcohol solvents (ethanol, butan-1-ol, ethylene glycol and glycerol) against autoxidation, a major barrier to the successful use of Hb in biological and medical engineering was studied, with these solvents, a large decrease in the autoxidation rate is observed over a range of concentrations. Studies on the effect of Hb concentration on autoxidation showed that, irrespective of the Hb concentration, oxyHb is more stabilized in water/alcohol solvents than in water. In these solvents, at the concentration exhibiting the maximal stabilizing effect, the oxygen affinity of Hb was little disturbed, but the changes in enthalpy and entropy of activation increased with the stabilization effect of alcohol. The impact of alcohols on the thermal denaturation of metHb was studied. We observed that metHb is less stable in ethanol and butan-1-ol than in water, whereas the opposite is observed with glycerol and ethylene glycol. The strong stability of oxyHb observed with these solvents could result both from an increase in water structure and an increase of viscosity. Finally, e.p.r. has shown that alcohols lead to an increase of the global distance between the nitrogens of proximal histidine (F8) and nitric oxide in the nitrosyl Hb.

1-Butanol↗
PubMed1992

Isolation and characterization of two opioid peptides from a bovine hemoglobin peptic hydrolysate.

Two opioid peptides were isolated from a bovine hemoglobin hydrolysate, by use of gel permeation (GP) and reverse phase (RP) high performance liquid chromatography (HPLC). Their primary structure and accurate molecular weights, determined by amino acid analysis and fast atom bombardment (FAB) mass spectrometry, were identical to fragments 31-40 (LVV-hemorphin-7) and 32-40 (VV-hemorphin 7) of the beta-chain of bovine hemoglobin. The same fragments occur in human hemoglobin in positions 32-41 and 33-41 of the beta-chain, respectively. The opioid potency of these peptides, exhibited by use of electrically stimulated muscle of isolated guinea-pig ileum (GPI), were significant and comparable with some others previously described. In addition, the location of the two opioid peptides, VV-hemorphin-7 and LVV-hemorphin-7, revealed the existence of a "strategic zone" both in the bovine and human beta-chains of hemoglobin.

Amino Acid Sequence↗
PubMed1992

Isolation and characterization of a bradykinin-potentiating peptide from a bovine peptic hemoglobin hydrolysate.

A bradykinin potentiating peptide was isolated from a peptic bovine hemoglobin hydrolysate, by the use of reversed-phase high-performance liquid chromatography (RP-HPLC). Its primary structure, determined by fast atom bombardment (FAB) and tandem mass spectrometry (MS/MS), was identical to fragment 129-134 of the alpha-chain of bovine hemoglobin. The bradykinin potency of this peptide, as exhibited by the guinea-pig ileum contraction, was significant and comparable with some others previously described.

Amino Acid Sequence↗
PubMed1991

Stabilizing effect of organic solvents on oxyhemoglobin.

The role of hemoglobin solutions as oxygen carriers in biotechnology are numerous, such as in the oxygen supply to biocatalysts or in the preparation of blood substitutes. However, the major barrier to the successful use of hemoglobin in biological and medical engineering is the autoxidation of heme iron during preparation, storage, and utilization. Fifty-six solvents, chosen among the group of Parker's classification, were studied with regard to the autoxidation kinetics of oxyhemoglobin under nondenaturant conditions. Among these solvents 27 present a concentration range in which the autoxidation rates were reduced compared to autoxidation in water. Three groups of solvent have been observed: one exhibiting only a destabilizing effect regardless of the solvent proportion, a second showing a strong stabilizing effect (k(H2O)/k(solvent) greater than 20) and a third showing a low stabilization (k(H2O)/k(solvent) less than 20). The most effective stabilizing solvents were glycerol, glycols, and alcohols. The effect of hydroorganic solvents could be explained by taking into account the globin solvation by water molecules. The solvents that enhance the structure of the water and form few hydrophobic interactions with globin prevent oxyhemoglobin autoxidation.

Humans↗
PubMed1990

Glutaraldehyde effect on hemoglobin: evidence for an ion environment modification based on electron paramagnetic resonance and Mossbauer spectroscopies.

Glutaraldehyde is a widely used reagent for hemoglobin cross-linking in blood substitutes research. However, hemoglobin polymerization by glutaraldehyde involves modifications of its functional properties, such as oxygen affinity, redox potentials, and autoxidation kinetics. The aim of this article is to investigate, by electron paramagnetic resonance and Mossbauer spectroscopies, the changes that occur in the iron environment after glutaraldehyde cross-linking. Spectrometric studies were performed with native hemoglobin and hemoglobin cross-linked as soluble and insoluble polymers. Spectrometry data comparison with glutaraldehyde-modified hemoglobin functional properties allows to interpret from a structural point of view that glutaraldehyde action occurs as a decrease of the O--N(F8His) distance, an increase of the Fe--N(F8His) bond length, and the decrease of the distal-side steric hindrance.

Cross-Linking Reagents↗
PubMed1989

Identification of peptides, from a peptic haemoglobin hydrolysate produced at pilot-plant scale, by high-performance liquid chromatography and mass spectrometry.

Gel-permeation high-performance liquid chromatography (HPLC) and reversed-phase HPLC were used to separate a mixture of peptides, produced at pilot-plant scale by peptic hydrolysis of bovine haemoglobin. Volatile buffers were employed in both HPLC techniques in order to get an easy recovery of peptides for further applications. The method is more rapid than low-pressure gel filtration. Amino acid analysis and fast atom bombardment mass spectrometry confirmed the purity, and allowed accurate molecular weights to be determined, for isolated peptides. These data demonstrate that such efficient techniques, usually used to resolve hydrolysates obtained in batch with pure substrates and highly specific enzymes, can be employed to resolve complex enzymatic hydrolysates of crude protein.

Amino Acid Sequence↗
PubMed1982

[A clinical study of tiapride in ten patients with chronic respiratory failure and in ten patients before fiberoptic bronchoscopy (author's transl)].

Ten patients with chronic respiratory failure (PaO2 = 56,19 +/- 10,54; PaCO2 = 49,17 +/- 7,31 torr) were given intramuscular injections of tiapride, Changes in alveolar ventilation were assessed clinically and by monitoring blood gases. No adverse effects were recorded. PaO2 was similar before and one hour after tiapride. There was no hypoventilation but, on the contrary, a slight decrease in PaCO2 (49,17 +/- 7,3 and 47,10 +/- 7,3 torr) and a significant increase in pH (7,358 +/- 0,023 and 7,378 +/- 0,028; p less than 0,05). Tiapride was also given to ten patients before fiberoptic bronchoscopy. Endoscopy was well tolerated in eight patients, in six there was no anxiety, and in all normal vigilance was retained.

Adult↗