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Biomedical subjects

M Bouvier

Publications and source records attributed to M Bouvier.

At least 127 records · Page 7Linked to original sources
PubMed1992

Agonist-modulated palmitoylation of beta 2-adrenergic receptor in Sf9 cells.

The palmitoylation of the human beta 2-adrenergic receptor (beta 2-AR) was studied in recombinant baculovirus-infected insect Sf9 cells. At 48 h post-infection, a high level expression of an epitope-tagged beta 2-AR (10-25 pmol/mg protein) was detected by [125I]iodocyanopindolol ([125I]CYP) binding assays. The identity of the receptor was confirmed both by photoaffinity labeling and immunoblotting. The fusion receptor displayed typical beta 2-AR pharmacological properties and conferred a beta-adrenergic sensitive adenylyl cyclase activity to the Sf9 cells. Moreover, exposure of the Sf9 cells to the beta-adrenergic agonist isoproterenol induced a rapid desensitization of the receptor-stimulated adenylyl cyclase activity. Purification of the epitope-tagged beta 2-AR by immunoprecipitation as well as by alprenolol-Sepharose affinity chromatography revealed that the receptor is covalently modified with palmitic acid in the insect cells as is observed in mammalian cells. In addition, short-term incubation of the cells with isoproterenol led to a specific increase in the incorporation of [3H]palmitate in the receptor, consistent with a rapid agonist-modulated turnover of the beta 2-AR-attached palmitic acid. These results suggest that agonist-mediated regulation of beta 2-AR post-translational palmitoylation could represent an other regulatory process for G protein-coupled receptors.

Affinity Labels↗
PubMed1992

Probing the functional conformation of neuropeptide Y through the design and study of cyclic analogues.

The functional importance of the PP-fold conformation in neuropeptide Y (NPY) was investigated. NPY and N alpha-Ac-NPY(10-36), and corresponding cyclic analogues cyclo18,22-[Lys18,Asp22]-NPY and N alpha-Ac-cyclo18,22-[Lys18,Asp22]-NPY(10-36), were synthesized. Strategies for synthesis of the cyclic analogues included the use of the Kaiser oxime resin and a segment condensation approach. Circular dichroism studies in phosphate buffer, pH 5.0, indicated self-association of all four peptides at low micromolar concentrations. Monomeric N alpha-Ac-NPY(10-36) showed only 13% alpha-helix, compared to 32% alpha-helix for monomeric NPY, demonstrating a helix-stabilizing effect of residues 1-9 that is consistent with the PP fold. The [Lys18,Lys22] lactam bridge stabilized the helical conformation in N alpha-Ac-NPY(10-36)(51% alpha-helix), but was helix destabilizing in NPY (21% alpha-helix). In rat brain receptor binding assays, the cyclic and linear N alpha-Ac-NPY(10-36) analogues were equipotent (IC50 = 13 nM for 125I-BH-NPY displacement), although the cyclic analogue was twice as potent in rat vas deferens assays. NPY was more potent than its cyclic analogue in the brain receptor binding assays (IC50 = 0.07 and 0.25 nM, respectively), but these peptides were equipotent in the vas deferens assays. These results support a functional role for the PP fold in NPY and correlate with the solution conformations of the monomeric peptides.

Animals↗
PubMed1992

Serum N terminal procollagen III fragment: a predictive marker of joint destruction in rheumatoid arthritis?

The level of the N terminal fragment of procollagen III (P3NP) levels of 100 consecutive patients affected by rheumatoid arthritis (RA) were evaluated in comparison with disease activity markers (erythrocytes sedimentation rate, C reactive protein), immunological status (rheumatoid factors, immune complexes) and joint destruction (assessed according to the Steinbrocker index). P3NP levels showed no significant relationship either to disease activity or to immunological status; however, a strong association was fond between X-ray grade and P3NP values. A two-year retrospective study of 32 patients belonging to the original 100 patient population allowed us to assign a predictive value for joint destruction to the P3NP level in the early stage of the disease.

Adult↗
PubMed1992

Presence of low amounts of "neuronal" antigens in cultured human skin fibroblasts.

To explore the utility of cultured skin fibroblasts in investigating diseases of the nervous system in which constituents characteristic of neurons are involved, sensitive immunochemical methods were used to test for the presence in skin fibroblasts of low amounts of proteins normally used as neuronal markers. The presence of each of the neurofilament triplet proteins and of neuron-specific enolase was demonstrated by immunoblotting and by immunocytochemistry, and of an 86-kDa synapsin-like material by immunoblotting. These observations agree with previous suggestions that readily available cultured fibroblasts may be useful in investigations of disorders in which molecules are involved which are typically associated with neurons in vivo, such as Alzheimer's disease.

Animals↗
PubMed1992

[Vertebral osteosclerosis, sacro-iliitis and palmoplantar dermatitis. Apropos of a case].

The authors report a case of aseptic vertebral osteitis which they classify in the context of SAPHO in view of the association with unilateral sacro-ileitis and palmoplantar dermatitis. They stress the importance of recognizing this disease which is initially suggestive of either a bone disease (Paget's disease, bone metastasis) or infectious discospondylitis.

Humans↗
PubMed1992

Distinct regulation of beta 1- and beta 2-adrenergic receptors in Chinese hamster fibroblasts.

The agonist-induced reduction of beta-adrenergic receptor (beta AR) cell surface density is a well documented phenomenon. The mechanisms responsible for this regulation have been well characterized for the beta 2AR. They include a rapid sequestration of the receptor away from the cell surface in a vesicular compartment and a longer term down-regulation of the total beta 2AR number. In contrast, very little is known about the cell surface regulation of the beta 1AR. In the present study, we have compared the agonist-mediated regulation of beta 1- and beta 2AR in Chinese hamster fibroblasts transfected with the cDNA encoding either beta AR subtype. Cells expressing similar numbers of the two beta AR subtypes were selected for the study. The expressed receptors exhibit typical beta 1- and beta 2AR selectivity for agonists and antagonists, as assessed by radioligand binding. Both receptors were found to be positively coupled to the adenylyl cyclase stimulatory pathway, but marked differences in the receptor regulation profiles were observed. Treatment of the cells expressing the beta 2AR with the agonist isoproterenol leads to a rapid sequestration of greater than 30% of the receptors away from the cell surface into a light vesicular fraction, where they are inaccessible to the hydrophilic ligand CGP-12177. In contrast, virtually no agonist-induced sequestration is observed in the cells expressing the beta 1AR. Longer exposure of the cells to isoproterenol leads to a time-dependent reduction in the total number of beta ARs in both beta 1- and beta 2AR-expressing cell lines. However, this down-regulation is significantly slower in the cells expressing the beta 1AR. In fact, no appreciable down-regulation of the beta 1ARs is detected in the first 4 hr of agonist treatment, compared with a down-regulation of greater than 50% of the beta 2ARs for the same period. After a 24-hr treatment with isoproterenol, less than 20% of the original number of beta 2ARs remain, whereas 60% of the beta 1ARs are still present after the same treatment. These results, therefore, suggest that, when expressed in an identical cell line, beta 1AR and beta 2AR follow distinct patterns of regulation. In fact, both agonist-induced sequestration and down-regulation are considerably blunted for the beta 1AR, compared with the beta 2AR.

Adenylyl Cyclases↗
PubMed1992

Effects of alverine on the spontaneous electrical activity and nervous control of the proximal colon of the rabbit.

To analyse the mechanisms of the antispasmodic action of alverine, the effects of this drug on the spontaneous motility and nervous control of the proximal colon of the rabbit were studied in vivo. The electrical activity of the colonic smooth muscle was recorded using extracellular electrodes. The parasympathetic efferents were activated by electrical stimulation of distal ends of the vagus nerves. Alverine given intravenously inhibits spike potentials without modifying the slow waves. Excitatory and inhibitory responses induced by parasympathetic efferent stimulations, as well as the hyperpolarization due to intraluminal distension, were also blocked after drug injection. Our results show that alverine is able to block the spontaneous contractions and the nervous control of rabbit proximal colon, indicating that this drug has powerful antispasmodic effects.

Animals↗
PubMed1992

[Rheumatoid metatarsals, original development of the first metatarsals].

Weight-bearing roentgenograms of 308 feet of rheumatoid arthritis patients were analyzed. Several angles were determined, including the metatarsus primus adductus angle (between the first and second metatarsals, > or = 10 degrees) and the forefoot spread angle (between the first and fifth metatarsals, > or = 30 degrees). Pes planus was diagnosed when the internal arch angle was equal to or greater than 130 degrees. Tarsal arthritis was defined as the presence of joint space narrowing. Varus of the first metatarsal was correlated with tarsal arthritis and pes planus but not with duration of the disease. Forefoot spread was correlated with duration of the disease and erosive metatarsal disease but not with involvement of the midfoot. These data demonstrate that orthopedic treatment should be initiated as soon as involvement of the first metatarsal is detected and should be directed at the hindfoot, midfoot, and first metatarsal whose deformations occur concomitantly.

Adult↗
PubMed1992

Clinical semiology of common cervicobrachial neuralgia. Data from 50 hospital cases.

Common cervicobrachial neuralgia is less frequent than sciatica and its aetiological profile is more varied: men and women are equally affected, triggering factors or previous history are less often found and patients with anxiety or depression are relatively numerous. Clinically, signs of C7 lesion are present in half the patients. Acroparesthesias are frequent and may be the initial signs. Nocturnal pain is present in 50% of the cases. Signs of neurological deficit are rare, except for abolition of a reflex. The association of cervicobrachial neuralgia with tendinitis of the upper limb or algodystrophy of the shoulder is too frequent to be fortuitous. Left to itself, the syndrome usually lasts several months and sometimes one year. Recurrences are rare. The most frequent sequela is a painful neck.

Brachial Plexus Neuritis↗
PubMed1992

Odontoblast response under carious lesions.

The local regulation of odontoblast response to caries is viewed through initiation and elaboration of sclerotic as well as reparative dentin. Dentin tissue represents a multiple source of potent environment factors when teeth are affected by the demineralization phases of carious process. Some of them have already been identified in sound tissue (matrix glycoproteins, proteoglycans, growth factors, Bone Morphogenetic Protein) and may act on the cell through membrane receptors. Thus, the amplification in collagen synthesis and alkaline phosphatase activity previously observed during sclerotic dentin deposition can be related to the interaction between matrix signals and cell receptors such as the 165 kDa protein shown only by odontoblasts under the affected zone. Similarly, under established lesions generating cell death, the specific matrix made of odontoblasts debris and damage tissues, probably rich in active molecules, may trigger pulp cells to elaborate a cartilage-like layer (identified by type II and XI collagen) followed by odontoblast-like cells to give rise to abnormal tubular dentin. Here, odontoblast response is identical to bone-cells response to injury. What remains to be elucidated concern: The nature of signals found in carious dentin (matrix components, growth factors, bacterial products). The nature and regulation of expression of cell membrane receptors during tooth repair. How the odontoblast produces specific responses to each of these signaling molecules will be the focus of important new investigations.

Cell Differentiation↗
PubMed1991

Phorbol-ester-induced phosphorylation of the beta 2-adrenergic receptor decreases its coupling to Gs.

Phorbol-esters have been shown to modulate the beta-adrenergic-stimulated adenylyl cyclase in a number of cell lines. Here, using site directed mutagenesis, we investigate the role of the beta 2-adrenergic receptor phosphorylation by protein kinase C in this regulatory process. Mutation of the serine-261, -262, -344 and -345 of the beta 2-adrenergic receptor prevented the phorbol-ester-induced phosphorylation of the receptor. This mutation also abolished the phorbol-ester-induced decrease in high-affinity agonist binding and potency of the beta 2-adrenergic receptor. We suggest that protein kinase C mediated phosphorylation of the receptor promotes its functional uncoupling.

Adenylyl Cyclases↗
PubMed1991

In vitro degradation of a poly(ether urethane) by trypsin.

In vitro enzymatic degradation of non-porous films of segmented poly(ether urethane) (Pellethane 2363-80AE) was investigated by incubating the biomaterial in concentrated trypsin solutions for 5 months at room temperature. Chemical degradation of films was monitored by surface analysis techniques such as Fourier transform infrared spectroscopy-attenuated total reflectance and electron spectroscopy for chemical analysis. This latter technique proved to be much superior in detecting chemical changes. Extraction of films with methanol and characterization of the extracts by gel permeation chromatography revealed the presence of low-molecular-weight polymers. Results have shown that trypsin has the ability to induce degradation in PEU, the soft segment being most affected, particularly the CH2-O bond of the ether linkages.

Biocompatible Materials↗
PubMed1991

Manometric and radiologic investigations and biofeedback treatment of chronic idiopathic anal pain.

In 12 patients suffering from chronic idiopathic anal pain, the rectosphincteric function was studied using manometric and x-ray techniques. The results of manometric investigations were compared with those obtained in 12 healthy volunteers. In all patients, the resting pressure in the anal canal was significantly higher than in control subjects. In 10 patients, defecography revealed abnormalities of the pelvic muscles. We treated the patients by using biofeedback techniques, consisting of voluntary modifications of the state of contraction of the external sphincter. In all cases, pain disappeared after a mean of eight biofeedback training sessions. When noxious manifestations had disappeared, manometry showed a significant decrease in the anal canal resting pressure. Our results indicate 1) that chronic idiopathic anal pain is associated with abnormal anorectal manometric profiles, probably resulting from a dysfunctioning of the striated external anal sphincter, and 2) that biofeedback training is an effective treatment for chronic idiopathic anal pain.

Adult↗
PubMed1991

Rheumatoid metatarsus. The original evolution of the first metatarsal.

Three hundred and eight unselected rheumatoid feet underwent a weight-bearing X-ray examination. If the malformations of the forefoot studied here present a statistical association, the primus metatarsus adductus is closely connected with tarsal arthritis and flattened foot but does not depend on the duration of the disease. The spread forefoot is indeed related to the duration of the disease and the presence of a metatarsal erosion at the foot level, but is not affected by the lesions of the midfoot. It appears then that an early orthopaedic treatment should be prescribed, once the first signs of involvement of the first ray or pronounced pronation of the hindfoot are noticed; it must affect the hindfoot, the midfoot and the first ray which progress together.

Adult↗
PubMed1991

Focal myositis: a pseudotumoral form of polymyositis.

The authors report a case of pseudotumoral focal myositis found in a 55 year-old man, in the anteroexternal area of the right leg. The diagnosis was based on the pathological findings, the absence of any further clinical signs or laboratory findings, and no further development over time. They compare their patient's characteristics with cases found in the literature (24 cases during the past 20 years). Diagnostic certainty confirms the benign character of this pathology, which contrasts with the gravity of the classical form of polymyositis.

Electromyography↗