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B Teisseire

Publications and source records attributed to B Teisseire.

At least 19 recordsLinked to original sources
PubMed1992

Specific esponse to 5-HT2 agonists by arterioles linked to Meth A tumors in mice.

Using intravital microscopy, we compared the responses to serotonin [5-hydroxytryptamine (5-HT)] and to a specific 5-HT2 agonist [1-(2,5-dimethoxy-4-bromo-phenyl)-2-aminopropane (DOB)] by normal arterioles and by the host-modified arterioles feeding a Meth A tumor implanted into the flank of female BALB/c mice. Topical and intravenous administration of 5-HT (10(-6) to 10(-4) M and 0.01-10 micrograms) or DOB (5 x 10(-7) to 5 x 10(-5) M and 0.01-10 micrograms) induced arteriolar constriction, which was far more pronounced for the arterioles feeding the tumor. This larger degree of vasoconstriction in tumor-feeding vs. normal arterioles was not found with norepinephrine. We also compared tumor growth and the mouse life span in three groups of mice, which were given 1 mg of serotonin or 0.74 mg DOB or saline solution. 5-HT or DOB both reduced tumor growth drastically compared with the controls (P less than 0.001), and survival rates were significantly higher in the 5-HT or DOB-treated groups (P less than 0.001). We conclude that 5-HT2-serotoninergic agonists are of particular pharmacological interest, since their vasoconstrictive action on the microvasculature feeding the tumors is much greater than in normal tissue and may interfere with tumor growth.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1992

Converting-enzyme inhibitors potentiate bradykinin-induced relaxation in vitro.

Experiments were designed to study the effects of converting-enzyme inhibitors (captopril and S 10211) on the endothelium-dependent relaxation to bradykinin in isolated porcine arteries. Rings of femoral arteries with and without endothelium were suspended in organ chambers to record isometric tension. Rings of coronary arteries without endothelium were used as bioassay tissue to record release of endothelium-derived relaxing factor (EDRF) from perfused femoral arteries. In organ chambers, bradykinin induced endothelium-dependent relaxation and, inconsistently, endothelium-independent contraction of the femoral artery rings. The relaxation is mediated by endothelial B2 bradykinin receptors, the contraction through B1 bradykinin receptors. Converting-enzyme inhibitors induced a weak potentiation of the contractile response and weak or no potentiation of the endothelium-dependent relaxation. In the presence of indomethacin, the response to bradykinin was not modified and no potentiation from the inhibitor could be observed. Blockade of the contractile response with a B1 bradykinin antagonist did not unmask a potentiation of the bradykinin endothelium-dependent relaxation by the converting-enzyme inhibitors. However, in the presence of B2 bradykinin antagonist, when high concentrations of bradykinin are required to induce relaxation, converting-enzyme inhibitors potentiated the effects of bradykinin. In contrast, in bioassay conditions with a perfused vascular segment, converting-enzyme inhibitors selectively enhanced the release of EDRF by bradykinin. This effect is observed in the bioassay tissue and in the donor segment. These results suggest that converting enzyme is indeed a powerful modulator of bradykinin action and that other enzymatic pathways of bradykinin metabolism present in the vascular wall could mask its action.

Acetylcholine↗
PubMed1992

Decrease in enkephalinase A number in kidney membranes from hypercholesterolemic and hypertensive rats.

The variation of enkephalinase A number on the hypertensive and hypercholesterolemia rats kidney membranes is studied using the [3H]-acetorphan, a potent inhibitor of enkephalinase A to label the protease in rat kidney. The binding of [3H]-acetorphan to kidney membrane determined in vitro with both equilibrium and kinetic methods is saturable and reversible involving a single class of sites with a dissociation constant of 4-5.3 nM. The [3H]-acetorphan binding capacity is identical, Bmax approximately 51 pmoles per mg of proteins, for kidney membranes from Sprague Dawley and Wistar Kyoto rats. In contrast, the enkephalinase A number is decreased in the pathological states studied: 20% for hypertensive rats and 50% for hypercholesterolemic rats. Such pharmacological results provide a great deal of information about the modification appeared in the metabolism of peptidic substrates of enkephalinase A in hypercholesterolemia and hypertension.

Animals↗
PubMed1990

Converting enzyme inhibition in isolated porcine resistance artery potentiates bradykinin relaxation.

The purpose of this study was to determine the effects of converting enzyme inhibition on the contractile reactivity of porcine femoral and intramuscular resistance arteries. The arteries were dissected free of hind limb skeletal muscle from anaesthetized pigs (Micro-pig Yucatan, Charles River), and were mounted in organ chambers and in a myograph system for tension recording. Bradykinin induced an endothelium-dependent relaxation in both vessels which was potentiated by S 10211, a converting enzyme inhibitor, only in resistance arteries. Under basal conditions angiotensin II and angiotensin I did not contract resistance arteries although contraction could be obtained with other agents such as KCl, noradrenaline or vasopressin. If the tone was increased with noradrenaline, angiotensin II and angiotensin I produced an increase in tension. S 10211 inhibited the increase in tension induced by angiotensin I but not by angiotensin II in vessels with and without endothelium. These results suggest that (1) converting enzyme is present in the vascular wall of porcine resistance arteries, (2) this enzyme is not necessarily located on the endothelial cells and, (3) converting enzyme could influence the responsiveness to angiotensin I and bradykinin.

Angiotensin II↗
PubMed1989

Arteriolar vasoconstriction and tachyphylaxis with intraarterial angiotensin II.

Several aspects of the differences between the responses of the second- to fifth-order arterioles (A2 to A5) to intraarterial administration of angiotensin II (AII) were studied by intravital microscopy on an original preparation of rat cremaster muscle. Dose-response curves displayed a leftward shift when the arteriolar order increased. Doses inducing 50% vasoconstriction were 15.1, 0.51, and 0.08 micrograms for A3, A4, and A5, respectively. For A2, very small vasoconstriction was found even at the highest dose of angiotensin II. The dynamics of the response were also dependent on the arteriolar order. The duration of the peak of vasoconstriction increased from A3 to A5, and the interval between the contact of vascular wall with drug and the response was smaller in A4 and A5 than in A3. To understand the effect of diameter as a determinant of heterogeneity in the degree of arteriolar vasoconstriction, norepinephrine was administered under the same conditions as angiotensin II, and responses were measured on arterioles with the same morphological characteristics as those examined after angiotensin II. When comparing the regression curves for the percentage of vasoconstriction vs diameter, we found that this relationship was drug dependent. The significantly steeper slope for angiotensin II than for norepinephrine excluded the possibility that heterogeneity of the degree of vasoconstriction is solely due to differences between the morphological characteristics of the arterioles. Since tachyphylaxis to AII is considered to be a reflection of the drug-receptor interaction, we also studied the magnitude of this phenomenon from proximal to distal parts of the arteriolar network. We showed that the degree of partial tachyphylaxis after 1 microgram AII was dependent on the arteriolar order and a decreasing tachyphylaxis gradient was evidenced from A3 to A5 arterioles.

Angiotensin II↗
PubMed1987

Long-term physiological effects of enhanced O2 release by inositol hexaphosphate-loaded erythrocytes.

A continuous lysing and resealing procedure with erythrocytes permitted incorporation in these cells of inositol hexaphosphate (InsP6), a strong allosteric effector of Hb. This leads to significant rightward shifts of the HbO2 dissociation curves with in vitro P50 (partial pressure of O2 at 50% Hb saturation), values increasing from 32.2 +/- 1.8 torr for control erythrocytes to 86 +/- 60 torr (pH 7.40; PCO2 40 torr at 37 degrees C; 1 torr = 1.333 X 10(2) Pa). The shape of the dissociation curve was still sigmoidal, although the Hill coefficient was decreased. The life span of InsP6-loaded erythrocytes equaled that of control erythrocytes. The long-term physiological effects of the InsP6-loaded erythrocytes on piglets were increased O2 release and reduced cardiac output. The reduced O2 affinity of the InsP6-loaded erythrocytes was still effective 20 days after transfusion in awake piglets. The electrolyte concentration appeared stable over the 5-day observation period except for a transient, but significant, hyperkalemia immediately after transfusion. The reductions in the O2 affinity of Hb reported here are large compared with previously reported values. Introduction of InsP6 into viable erythrocytes improves tissue oxygenation when, for any reason, normal blood flow is impaired.

Animals↗
PubMed1987

Oxygen transport to tissue modified by entrapment of an allosteric effector of haemoglobin in erythrocytes.

Oxygen affinity of haemoglobin is modulated by several parameters such as the allosteric effector 2-3 DPG for most mammalians. Inositol hexaphosphate (I.H.P.) exerts the same effect on haemoglobin. A previously developed new methodology for the entrapment of drugs into erythrocytes has been adapted to I.H.P.; it is based on a reversible osmotic shock. I.H.P. loaded red blood cells have characteristics very similar to those of native cells. The decrease in oxygen affinity is related to the dose of encapsulated I.H.P. In piglets, transfusion of such cells has led to an increase of oxygen extraction from haemoglobin. Normal anesthetized animals regulate their oxygen consumption by reduction of cardiac output.

2,3-Diphosphoglycerate↗
PubMed1986

Laser angioplasty of arterial stenoses.

To establish the optimal conditions for recanalization of obstructed arteries without damage to vessel walls, an Nd-YAG laser coupled to a 0.2-mm-diameter optical fiber was used on obstructed human cadaver coronary and peripheral arteries and on popliteal arteries in amputated limbs. Vaporization of atheromatous plaques was consistently obtained with energy of 360-600 J and a diluted blood perfusate (3 g/100 ml hemoglobin) at a rate of 30 ml/min. The arterial wall was protected from thermal injury by inserting the optical fiber into an inflated balloon catheter and by cooling the system with the perfusate. Since recanalization of occluded arteries was consistently obtained without damage to the arterial wall or debris and thin and flexible optical fibers were easy to guide in the arteries, percutaneous transluminal Nd-YAG laser angioplasty was used in obstructed femoral and popliteal arteries in 12 patients. The first trials in man with Nd-YAG laser showed the method to be feasible, effective, and at low risk, although further studies are required to improve penetration of the obstruction and increase the diameter tunnel.

Angioplasty, Balloon↗
PubMed1979

Attempts to use carbodiimide (EDCI) to cross-link hemoglobin for transfusions.

The polymerization of hemoglobin for use as a blood substitute and an oxygen carrier would be of interest because high-mol. wt macromolecules would have a longer vascular retention time than the monomer. We found that the molecules resulting from the treatment of hemoglobin with ethyldimethylaminopropylcarbodiimide did not have a higher mol. wt than free hemoglobin and also had a dissociation curve resembling that of monomers, but seemed more stable.

Carbodiimides↗
PubMed1979

Comparative effects of CO2 on the affinity for O2 of fetal and adult erythrocytes.

1. Oxygen-linked carbamino formation in fetal erythrocytes was compared to that measured in adult erythrocytes. 2. Whole oxygen binding curves were recorded on washed intact erythrocytes either fresh or D-glycerate-2,3-P depleted with a continuous recording technique. Erythrocytes were resuspended in buffer media of different pH and PCO2 varying from 0-10.7 kPa (80 torr) at physiological ionic strength. Oxygen linked carbamates were estimated as deltalog PO2/delta log PCO2 at constant pH and constant saturation levels from 10-90% oxygen saturation. 3. The overall CO2 effect (deltalog P50/deltalog PCO2) was consistently lower in fetal erythrocytes than in the adult. The deltalog PO2/deltalog PCO2 ratio was markedly dependent on oxygen saturation in both types of erythrocytes and highest at the early part of the oxygen binding curve. This was more so in fetal erythrocytes. 4. Carbamino formation was lower in fetal erythrocytes than in adult erythrocytes at any pH value, indicating a higher apparent pK of the alpha amino groups involved in CO2 binding in fetal erythrocytes. This may be related to the different primary structures of the non alpha chains of HbFII and HbAI. 5. The large effect of low PCO2 on both fetal and adult erythrocytes was related to the higher affinity for CO2 of deoxyhemoglobin compared to oxyhemoglobin and a model for CO2 binding analogous to that described by de Bruin et al. [6] for anion binding is proposed. 6. It is concluded that the lower CO2 binding to fetal erythrocytes is in keeping with the lower allosteric effect of other major effectors of hemoglobin within the cells. This leads to a higher affinity for O2 of fetal erythrocytes well suited for O2 transport in utero.

Adult↗
PubMed1979

[Acute respiratory failure: comparison of spontaneous ventilation with continuous positive airway pressure (CPAP) and mechanical ventilation with positive and expiratory pressure (CPPV) in 6 cases (author's transl)].

The hemodynamic and respiratory effects of spontaneous ventilation with continuous positive airway pressure (CPAP) and mechanical ventilation with positive and expiratory pressure (CPPV) were compared in six patients with acute respiratory failure. Arterial and mixed venous gases, cardiac output, oxygen delivery and consumption, airway and oesophageal pressures were measured, with each patient on intermittent positive pressure ventilation (IPPV), CPAP and CPPV with the same level of positive and expiratory pressure (PEEP = 20 cmH2O). CPAP was as efficient as CPPV for improving arterial oxygenation. Cardiac output was higher on CPAP than on CPPV due to a lower intra-thoracic pressure with spontaneous ventilation, thus oxygene transport was higher with this methode. However total oxygene consumption and PaCO2 were slightly increased with CPAP due to a higher breathing's work. So, CPAP is as efficient as CPPV at the same level of PEEP in improving intra-pulmonary shunt and PaO2, without adversely affecting cardiac output.

Heart Rate↗
PubMed1979

Effect of an increase in HbO2 affinity on the calculated capillary recruitment of an isolated rat heart.

The effect of an increase in hemoglobin O2 affinity on myocardial O2 delivery was studied in a blood perfused working rat heart preparation. In a first series of experiments P50 (PO2 for which saturation is 50%) was lowered by use of carbon monoxide. The heart was alternatively perfused with the blood sample of P50 = 32 mm Hg and the blood sample of P50 = 17 mm Hg. O2 capacity of both samples was kept the same by appropriate hemodilution. In a second serie of experiments change of P50 was obtained by the use of adult human erythrocytes containing hemoglobin creteil with a P50 of 13.6 mm Hg. As P50 decreased from 25 to 10 mm Hg, coronary sinus PO2 (PcsO2) diminished from 26 +/- 2 to 18 +/- 2 mm Hg (-29 +/- 2%), coronary sinus O2 content (CcsO2) increased by 15 +/- 3%, myocardial oxygen consumption did not change significantly. The percentage of increase of coronary flow was 23 +/- 4%. Analysis of these results with a simple mathematical model of O2 delivery suggest that increase in HbO2 affinity is corrected by a simultaneous increase in coronary flow and capillary recruitment.

Animals↗
PubMed1979

Comparative haemodynamic effects of dopamine and dobutamine in septic shock.

Septic shock associated with depressed myocardial function generally requires the use of catecholamine. Currently dopamine is often selected. Dobutamine is a newly developed catecholamine which has been shown to be of value in severe cardiomyopathic disease. The aim of this work was to determine the most appropriate drug by comparing haemodynamic responses to dopamine and dobutamine in 19 studies carried out in 11 patients with septic shock and heart failure. Cardiac index increased siliarly with dopamine and dobutamine (33%), as did stroke volume (respectively 26.4 and 25%). Arterial pressure increased by 17% with dopamine whereas it did not significantly change with dobutamine due to reduction in vascular resistance of 19%. Dobutamine decreased filling pressure, either right (14%) of left (28%) whilst they slightly but unsignificantly increased with dopamine. Pulmonary shunting increased more with dopamine (47%) than with dobutamine (16%), but PaO2 remained constant with both. Since septic shock is characterized by lowered arterial pressure and vasodilatation it is concluded that effects of dopamine on capacitance and resistance vessels make this drug more suitable. In addition it selectively increases renal blood flow. Nevertheless dobutamine could be appropriate, in case of very high filling pressures, severe peripheral vasoconstriction, marked pulmonary shunting and in some cases where dopamine becomes ineffective.

Catecholamines↗
PubMed1979

Hyperkinetic shock in viral and pneumococcal pneumonias.

Ten patients, suffering from severe viral or bacterial pneumonia had circulatory shock, characterised haemodynamically by normal or high cardiac output (CI = 4.1 +/- 1.2 1/min/m2) and low systemic resistance (SVR = 14 +/- 3.7 mm Hg/1/min/m2). Existence of such a hyperkinetic state greatly complicates the management of patients. Plasma volume expansion, performed in five cases of initial hypovolaemia, and Dopamine infusion (five patients) increased markedly the intra-pulmonary shunting. High level PEEP ventilation was not tolerated, despite the improvement of blood gases it produced. Extra-corporeal membrane lung oxygenation (three cases), whilst giving an initial decrease of shunting and restoring SVR, produced no long term surviors. All ten patients died from intractable shock and severe hypoxaemia. Spontaneous ventilation with positive expiratory pressure (CPAP) is believed to be an attractive alternative, due to its absence of deleterious haemodynamic effects.

Adult↗
PubMed1978

Chloride binding and the Bohr effect of human fetal erythrocytes and HbFII solutions.

1. We have observed that the alkaline Bohr effect of washed human fetal erythrocytes was larger than in human adult intact red cells, in physiological conditions of pH, PCO2 and temperature. This was also observed independently of the presence of CO2 and of 2,3 diphosphoglycerate (fresh or stored erythrocytes). 2. Experiments performed in purified HbFII and HbA1 solutions and direct titration of protons released upon oxygenation confirmed the larger alkaline Bohr effect of fetal hemoglobin, at physiological ionic strength. 3. At low chloride concentration HbFII solutions had an alkaline Bohr effect identical to that measured in HbA1 solutions. 4. Titration of purified Hb solutions with increasing concentrations of NaCl evidenced a lower O2 linked chloride binding by HbFII and predominantly at acid pH. 5. It is concluded that the larger alkaline Bohr effect of fetal erythrocytes of HbFII solutions is related to a diminished acid Bohr effect, due to the lower affinity of HbFII for chloride anions. 6. The physiological interest of these results for placental O2 transfer (double Bohr effect) and O2 delivery to the foetus is discussed.

Aging↗