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Biomedical subjects

A Fournier

Publications and source records attributed to A Fournier.

At least 343 records · Page 19Linked to original sources
PubMed1992

Inhibitory action of neuropeptide Y on agonist-induced responses in isolated guinea pig trachea.

The effect of neuropeptide Y (NPY) was tested on isolated guinea pig trachea. At 30 nM, NPY induced a weak but significant contractile response which was on average less than 6% of responses elicited by standard spasmogens. This myotropic action of NPY was blocked by indomethacin. In addition to its contractile activity, NPY greatly reduced the maximal response to vasoactive intestinal peptide (VIP), noradrenaline (NA), substance P (SP) and 5-hydroxytryptamine (5-HT), without affecting their pD2 values. However, NPY did not influence the response induced by histamine and carbamylcholine. Pretreatment of tracheal spirals with indomethacin (10(-6) M) abolished the NPY-evoked inhibition of VIP, SP and 5-HT responses but failed to reduce the action of NPY on NA-elicited relaxation. This latter effect was however blocked in the presence of tetrodotoxin. In conclusion, NPY inhibits responses elicited by various agonists in the guinea pig trachea. This effect seems to be mediated at both pre- and postjunctional levels. The postjunctionally mediated inhibitory action of NPY appears to be expressed especially with agents that generate prostaglandins concomitantly with inducing their response. In contrast, the NPY-evoked inhibition of NA-evoked relaxation seems to be mediated via a prejunctional mechanism.

Airway Resistance↗
PubMed1992

Structure-activity study of hCGRP8-37, a calcitonin gene-related peptide receptor antagonist.

A structure-activity study was carried out to determine the importance of the N-terminal amino acids of hCGRP8-37 in binding and antagonistic activity to CGRP receptors. Therefore, fragments of hCGRP8-37 as well as analogs obtained by the replacement of residues 9-12 by L-alanine were synthesized by solid-phase peptide synthesis, using BOP as a coupling reagent. The affinities of the peptides to CGRP receptors were evaluated in the rat brain, guinea pig atrium, and guinea pig vas deferens membrane preparations. Their antagonistic activities were measured in the guinea pig atria and rat vas deferens bioassays. The pharmacological characterization showed that arginine-11 and leucine-12 play a crucial role for the affinity of hCGRP8-37. Interestingly, it was observed that [Ala11]hCGRP8-37 was able to potentiate the twitch response of the electrically stimulated rat vas deferens. On the other hand, the substantial antagonistic potencies of analogs [Ala9]-, [Ala10]-, and [Ala12]hCGRP8-37, as compared to those of the fragments hCGRP10-37, hCGRP11-37, and hCGRP12-37, suggest that the side chains of Thr-9, His-10, and Leu-12 assume mainly a structural role. Accordingly, the conformational characterization of these peptides by circular dichroism spectroscopy revealed that the residues 9-12 are important for the integrity of the amphiphilic alpha-helix of hCGRP8-37.

Amino Acid Sequence↗
PubMed1992

Endothelin-1 enhances vascular permeability in conscious rats: role of thromboxane A2.

The purpose of the present experiments was to study the effects of endothelin-1 (ET-1) on vascular permeability and the involvement of the cyclooxygenase metabolites in the vascular responses to ET-1. Bolus intravenous injection of ET-1 (0.1-1.0 nmol/kg) into conscious rats induced immediate hypotension lasting for 30 s followed by sustained dose-dependent hypertension. A low dose of ET-1 (0.1 nmol/kg) did not modify the hematocrit value but the 1.0-nmol/kg dose increased the hematocrit value from 39.7 to 44.4%. Pretreatment of the animals with BM-13505 (1 mg/kg), a thromboxane A2 (TxA2) receptor antagonist, prolonged the duration of the hypotensive response to ET-1 (1.0 nmol/kg) but had no effect on the pressor response. Pretreatment with OKY-046 (10 mg/kg), a TxA2 synthesis inhibitor, or indomethacin (10 mg/kg), a cyclooxygenase inhibitor, had no significant effect on ET-1-induced changes in blood pressure. Evans blue dye extravasation, a marker of vascular permeability, increased up to 235% over control levels in specific vascular beds including the upper and lower bronchi, stomach, duodenum and kidney of ET-1 (1.0 nmol/kg)-treated animals. Pretreatment of the animals with BM-13505, OKY-046 or indomethacin reduced by 60-100% the Evans blue extravasation in these tissues. These results suggest that the effect of ET-1 on vascular permeability is partly mediated and/or modulated by the secondary release of TxA2, whereas its action on arterial blood pressure appears to be independent from prostanoid release in conscious rats.

Animals↗
PubMed1992

Effectiveness of oral sotalol for treatment of pediatric arrhythmias.

Sotalol is a beta blocker with class III activity. Few investigators have reported its use in pediatric patients. From August 1985 to May 1990, 66 patients (mean age 8.7 years; range 9 days to 24 years), including 14 infants aged less than 3 months, were treated with oral sotalol alone (n = 46) or in association with digoxin (n = 20). Supraventricular reentrant tachycardia was present in 38 patients (20 with documented preexcitation), atrial flutter in 10 and atrial ectopic tachycardia in 7. Three patients had other types of supraventricular tachycardia. Tachycardia was of ventricular origin in 6 patients and both of supraventricular and ventricular origin in the remaining 2. Mean dose of oral sotalol was 135 mg/m2/day given in 2 doses. Congenital heart disease was present in 28 patients, 14 with previous cardiac surgery, mostly at the atrial level. Prior treatment with 1 or more antiarrhythmic agent had been unsuccessful in 83% of patients. Mean duration of treatment was 13.3 months (range 2 months to 5 years). Overall, treatment was successful in 79% of cases. Highest rate of success was observed in patients with supraventricular reentrant tachycardia with or without preexcitation (89%) and in those with atrial ectopic tachycardia (85.5%). Atrial flutter could be controlled in 60% of cases. Sotalol seemed less effective in ventricular tachycardia with a complete control of the arrhythmia being achieved in only 17%; however, it decreased the number of runs of ventricular tachycardia and the number of ventricular premature complexes in 50% of patients. There were no adverse effects in 89% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Production of alginate beads by emulsification/internal gelation. I. Methodology.

Small diameter alginate beads (microspheres) were formed via internal gelation of alginate solution emulsified within vegetable oil. Gelation was initiated by addition of an oil-soluble acid thereby reducing the pH of the alginate solution and releasing soluble Ca2+ from the citrate complex. Smooth, spherical, micron-sized beads were formed. The mean diameter ranged from 200 to 1000 microns, controlled by the reactor impeller design and rotational speed. The technique has potential for large-scale and continuous applications in immobilization.

Alginates↗
PubMed1992

Correlation between gI, gII, gIII, and gp 50 antibodies and virus excretion in vaccinated pigs infected with pseudorabies virus.

Eleven groups of 8 pigs were vaccinated with different vaccinal strains of pseudorabies virus deleted or not for non-essential glycoproteins (gI, gX, gp 63), then were challenged 8-9 weeks later with a virulent strain. Antibodies against the major viral glycoproteins (gII, gIII, gp 50) were titrated at the day of challenge. Excretion of the challenge strain, growth performance of the pigs, and gI antibody responses from pigs vaccinated with a gI minus strain, were monitored after the challenge. The results demonstrated a strong association between gII and gIII antibody titres before the challenge, with the amount of the challenge strain excreted and clinical protection after the challenge. Furthermore, gI antibody titres after the challenge were negatively correlated with the level of gII and gIII antibodies at the day of challenge, the virus excretion and the clinical protection after the challenge. Implications of these results for vaccination of pigs and gI antibody screening for the infection are discussed.

Animals↗
PubMed1992

Usefulness of oral sotalol for the treatment of junctional ectopic tachycardia.

An infant with junctional ectopic tachycardia diagnosed at three weeks of age was treated with oral sotalol. At the first echocardiogram the shortening fraction was decreased. After one day of treatment the ventricular rate decreased from 230 to 130 beats per minute. Five months later sinus rhythm was restored, shortening fraction was normal and sotalol was withdrawn without relapse.

Administration, Oral↗
PubMed1992

Non-aluminic adynamic bone disease in non-dialyzed uremic patients: a new type of osteopathy due to overtreatment?

Adynamic bone disease, characterized by a low bone formation rate with normal or reduced amount of unmineralized osteoid, is supposed to be the consequence of aluminum intoxication in uremic patients. However, the emergence of adynamic bone disease has been recently reported in hemodialyzed patients in the total absence of aluminum overload. This study was aimed to assess whether such a histological pattern of adynamic bone disease was already present in uremic patients not yet on dialysis. Twenty-seven asymptomatic uremic patients (mean age +/- SD 43 +/- 10 years, mean creatinine clearance 19 +/- 3 ml/mm) were studied and bone biopsies were repeated in 16 of them after 18 +/- 10 months of treatment with oral calcium carbonate (1-3 g of elemental calcium/day) and calcidiol (21 +/- 14 micrograms/day). None of the patients received aluminum hydroxide, and the search for bone aluminum deposits was negative in all patients both before and after treatment. Two patients fulfilled the criteria of adynamic bone disease on their post-treatment biopsies. They originated from patients classified as having normal bone histology before treatment. Comparison with the other patients showed that they had comparable plasma C-terminal PTH but higher plasma creatinine than patients with normal bone histology and lower plasma C-terminal PTH than patients with osteitis fibrosa but comparable plasma creatinine. The plasma levels of 1,25(OH)2D reached values above normal after treatment in these two patients. It is suggested that adynamic bone disease not related to aluminum intoxication can develop in uremic patients independently of dialysis, and is favored by a relative hypoparathyroidism for the degree of renal failure, possibly induced by elevated plasma concentrations of calcitriol.

Adult↗
PubMed1992

Ketodiet, physiological calcium intake and native vitamin D improve renal osteodystrophy.

The effects of a very low-protein diet (VLPD) supplemented with amino acids and ketoanalogues (KA) and with 1 g of calcium carbonate and 1000 IU of vitamin D2, were studied in 17 patients with advanced renal failure (GFR < or = 20 ml/min) over a period of one year. The protein intake was 0.3 g protein/kg body wt/day. Daily phosphorus and calcium intake were respectively 1,500 mg and 300 mg. Sequential bone densitometry was performed and bone histomorphometry after double tetracycline labeling was evaluated, before and after one year of diet. Calcium and phosphate metabolism parameters were monitored every two months. In spite of a significant decrease of GFR, phosphorus, parathyroid hormone (1-84) and osteocalcin plasma levels decreased significantly, while low plasma bicarbonate normalized, and calcitriol and calcium levels remained respectively low and normal. Before the diet, histological study disclosed four cases of mixed osteopathy: osteomalacia associated with osteitis fibrosa (OM/OF), nine pure osteitis fibrosa (OF) and four with normal bone remodeling (NB). After one year of diet, the OM component of OM/OF disappeared, as evidenced by a normalization of the mineral apposition rate and osteoid thickness. In the patients presenting pure OF, a significant decrease in osteoblastic and osteoclastic surfaces, in the number of osteoclasts, and in the bone formation rate (BFR) were found. Vertebral mineral density measured by quantitative computerized tomodensitometry did not change significantly. In conclusion, this study not only confirms the beneficial effects of VLPD + KA + calcium on uremic hyperparathyroid bone disease in advanced renal failure assessed using static bone histomorphometry, but also shows a correction of histodynamic bone parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Non-neutralizing monoclonal antibodies against Ras GTPase-activating protein: production, characterization and use in an enzyme immunometric assay.

We studied several monoclonal antibodies (mAbs) raised against the 100 kD Ras GTPase activating protein (p100-GAP), which was purified from human placenta. These antibodies recognized p120-GAP and p100-GAP in native and in denatured forms. The most reactive, GP15 and GP200, both recognized distinct epitopes and did not neutralize GTPase stimulatory activity. These two mAbs were selected for a two-site enzyme immunoassay, using covalent conjugates of the antibodies coupled to the tetrameric form of acetylcholinesterase as tracer. This assay was used to quantify Ras-GAP in both normal and tumor tissues and cell extracts.

Animals↗
PubMed1992

Intestinal transfer of manganese: resemblance to and competition with calcium.

The effect of calcium, phosphate and the sugars lactose and sorbitol on the intestinal absorption of manganese were studied in adult male rats. Gastric gavage showed that lactose (100 mM or 200 mM) increased the hepatic retention of 54Mn, while phosphate decreased it. In situ ileal loop studies indicated that Mn absorption was normally complete in 30 min. Sorbitol had no effect on uptake during this period, but extended Mn absorption from 30 min to 120 min. Low concentrations of Mn (10 microM) did not alter the enhancing effect of lactose on calcium transport (10 mM), but the enhancing effect of lactose on Mn transport was blocked by this high calcium concentration. Intestinal alkaline phosphatase activity was rapidly stimulated by Mn. These similarities plus the competition between cations, especially calcium, suggest that a common mechanism exists in their intestinal transport.

Alkaline Phosphatase↗