Biomedical subjects

M Hubert

Publications and source records attributed to M Hubert.

At least 19 recordsLinked to original sources

PubMed1997

First pharmacokinetic-pharmacodynamic study in humans with a selective 5-hydroxytryptamine4 receptor agonist.

This report describes the first study in humans with SDZ HTF 919 (HTF), a novel, selective 5-hydroxytryptamine4 (5-HT4) receptor partial agonist and investigates its tolerability, pharmacokinetics, and pharmacodynamics. Three cohorts of 12 men, of whom 8 were treated with active drug and 4 with placebo, participated in the double-blind, randomized, parallel-group, ascending-dose study. A single dose and subsequently twice-daily multiple doses of 25, 50, and 100 mg were given for 14 days. Adverse events, clinical laboratory variables, electrocardiogram, vital signs, and psychometric effects were recorded. Basic pharmacokinetic characteristics of HTF were derived. Loose stool and total colonic transit time were assessed. Mild to moderate adverse gastrointestinal events, predominantly loose stools, occurred at all dose levels and reflect the pharmacologic properties of HTF. The incidence of headache increased with dose. Dose-normalized (to 25 mg) systemic exposures were 25 +/- 12, 19 +/- 11, and 26 +/- 10 hr.ng/mL in single doses and 26 +/- 12, 23 +/- 12, and 33 +/- 12 hr.ng/mL in multiple doses for the three doses. Steady-state concentrations of HTF were reached after 8 days of daily administration and moderate accumulation was observed. Loose stool occurred on average between 2 and 4 hours after drug administration. The overall HTF-mediated median decrease from baseline (26 and 38 hours) in total colonic transit time was 4.8 hours, versus 1.8 hours with placebo. In conclusion, the novel 5-HT4 receptor agonist HTF was tolerated at oral doses of 25 mg to 100 mg administered twice daily. Pharmacokinetics in both single and multiple doses indicate no deviation from dose proportionality. The applicability of the total colonic transit time as a measurement of surrogate prokinetic effect warrants further investigation in patient populations.

Adult↗

PubMed1996

Structural and functional characterization of tenascin-R (restrictin), an extracellular matrix glycoprotein of glial cells and neurons.

Tenascin-R (TN-R) is an extracellular matrix protein associated with the surface of neurons and glial cells. Immunohistological studies reveal that TN-R shows a restricted expression pattern in the developing nervous system. TN-R is the smallest member of the tenascin family and is composed of four structural motifs: a cysteine-rich segment at the N-terminus is followed by 4.5 EGF-like repeats. This region is followed by 9 consecutive fibronectin type III (FNIII)-like domains and at the C-terminus TN-R is related to the beta- and gamma- chains of fibrinogen. TN-R forms oligomeric structures as revealed by rotary shadowing electron microscopy of immunoaffinity-purified TN-R. TN-R interacts with the axon-associated F11 protein which results in an enhancement of F11 mediated neurite extension in in vitro assays. In short-term adhesion assays it was found that neural but not fibroblastic cells attach effectively on immobilized TN-R. The cell attachment site within TN-R was allocated to FNIII domain 8 while the site interacting with the F11 protein could be mapped to FNIII domain 2-3.

Animals↗

PubMed1995

Intranuclear distribution of galectin-3 in mouse 3T3 fibroblasts: comparative analyses by immunofluorescence and immunoelectron microscopy.

The intracellular distribution of carbohydrate binding protein 35 (CBP35), recently named galectin-3, was studied in mouse 3T3 fibroblasts, using immunofluorescence at the light microscope level and immunogold labeling at the ultrastructural level. In general, serum-stimulated, proliferating cells showed higher levels of labeling than quiescent cultures of the same cells. In the proliferating cells, the labeling intensity was higher in the nucleus than in the cytoplasm. Treatment of permeabilized cells or thin sections with ribonuclease A decreased the immunolabeling intensity, whereas parallel control treatments with deoxyribonuclease I failed to yield the same effect. While there appears to be general agreement between the immunofluorescence and the ultrastructural results regarding the level of CBP35 and its association with nuclear ribonucleoprotein complexes, there was one striking difference in terms of labeling of specific subnuclear structures. Immunofluorescence results indicate diffuse distribution of CBP35 within the nucleus, but the label appears to be excluded from certain "black holes," which most probably correspond to nucleoli. On the other hand, immunogold particles were observed in electron microscopy, mainly in interchromatin spaces, except for interchromatin granule clusters, at the border of condensed chromatin, on the dense fibrillar component, and at the periphery of the fibrillar centers of nucleoli.

3T3 Cells↗

PubMed1995

Characterization of functional domains of the tenascin-R (restrictin) polypeptide: cell attachment site, binding with F11, and enhancement of F11-mediated neurite outgrowth by tenascin-R.

The extracellular matrix glycoprotein tenascin-R (TN-R) is a multidomain protein implicated in neural cell adhesion. To analyze the structure-function relationship of the different domains of TN-R, several recombinant TN-R fragments were expressed in bacterial cells. Two distinct binding regions were localized on the TN-R polypeptide: a region binding the axon-associated immunoglobulin (Ig)-like F11 protein and a cell attachment site. The binding region of the glycosylphosphatidylinositol (GPI)-anchored F11 was allocated to the second and third fibronectin type III (FNIII)-like domain within TN-R. By using a mutant polypeptide of F11 containing only Ig-like domains, a direct interaction between the Ig-like domains of F11 and FNIII-like domains 2-3 of TN-R was demonstrated. The interaction of TN-R with F11 in in vitro cultures enhanced F11-mediated neurite outgrowth, suggesting that the combined action of F11 and TN-R might be of regulatory influence on axon extension. A cell attachment region was identified in the FNIII-like domain eight of TN-R by domain-specific antibodies and fusion constructs. This site is distinct from the F11 binding site within TN-R.

Animals↗

PubMed1995

Genotype and phenotype relationships for mutations in the ryanodine receptor in patients referred for diagnosis of malignant hyperthermia.

Anaesthesia-induced malignant hyperthermia (MH) may be caused by specific gene defects in the skeletal muscle ryanodine receptor. We have studied the frequency of occurrence of the C1840T mutation, analogous to the porcine mutation, and three mutations associated both with MH and central core disease (G7301A, C487T and C1209G). We investigated skeletal muscle specimens from up to 137 patients testing negative and 101 patients testing positive for MH susceptibility by the North American MH Group protocol. The presence or absence of the mutations was determined by polymerase chain reaction and restriction enzyme digestion. The frequencies of occurrence of the C1840T and C487T mutations were 2% and 1%, respectively, in MH-positive subjects and were the only two mutations identified. One subject with central core disease did not have any of the three mutations examined associated with this disorder. Therefore, the porcine and central core disease-associated mutations examined in the ryanodine receptor account for a small proportion (approximately 3%) of MH-positive diagnoses. The mutations examined did not occur in any of the MH-negative patients, supporting an association between defects in the ryanodine receptor and a positive diagnosis for MH.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthetics, Inhalation↗

PubMed1995

Study of muscular effects of short-term pyridostigmine treatment in resting and exercising rats.

1. Pyridostigmine (PYR) pretreatment is used by the military to obtain 20-30% whole blood acetylcholinesterase (AChE) inhibition in order to enhance the effectiveness of the standard therapeutic regimen for poisoning by an organophosphate anticholinesterase agent. The present study was undertaken to investigate in a rat model the potential muscle damage produced by this pretreatment when given alone or combined with physical exercise. 2. Grip strength and biochemical measurements, i.e. serum creatine phosphokinase (CPK) activity and creatine urinary excretion rate, together with histological studies, were performed in resting animals during a period of 14 days of PYR administration in a dose producing 20-30% whole blood acetylcholinesterase inhibition. No evidence was found of a deleterious effect of this treatment on the skeletal muscle. 3. In contrast, following physical exercise, the same treatment significantly exacerbated the biochemical changes reflecting a loss of integrity in skeletal muscles, namely, increased CPK and urinary creatine excretion rate. The significance of this observation remains to be clarified.

Animals↗

PubMed1994

[Modification and optimization of tap water iontophoresis].

Tap water iontophoresis is the therapy of choice in hyperhidrosis palmoplantaris. Therapeutic regimens, however, vary greatly. The aim of the present study was to develop an optimized therapeutic scheme. The main methodologic parameters subjected to systematic experimental study included the effects of current polarity, the duration of a single treatment session, the addition of electrolytes to the tap water and the treatment interval during maintenance therapy. The following procedure is proposed. During the initial phase, treatments are carried out three times weekly for 10 min each time. The anode is kept on one extremity until normhidrosis is reached on this extremity. Then, polarity is changed until sweating is reduced to normal on the other extremity (constant polarity). In the subsequent maintenance phase, patients are treated at intervals of 6-8 days for 10 min each time. Polarity is switched from treatment to treatment (alternating polarity). Plain tap water is used without additives.

Adolescent↗

PubMed1993

The axonal recognition molecule F11 is a multifunctional protein: specific domains mediate interactions with Ng-CAM and restrictin.

F11 is a glycosyl phosphatidylinositol-anchored axonal surface glycoprotein belonging to a neural subgroup of the immunoglobulin superfamily. In this report, we demonstrate that the F11 protein displays three distinguishable activities: binding to the cell recognition molecule Ng-CAM, interaction with the extracellular matrix glycoprotein restrictin (RN), and a neurite outgrowth-promoting activity. By analyzing deletion mutants expressed in transfected COS cells, epitope mapping of monoclonal antibodies, and neurite outgrowth assays, we reveal that these activities can be localized to distinct regions within the F11 protein. The Ng-CAM-binding site resides in the first two immunoglobulin-like domains of F11, whereas the RN-binding site resides in the second or third domain. A neurite outgrowth-promoting activity of F11 characterized by in vitro culture of tectal cells is independent of F11-Ng-CAM and F11-RN binding.

Animals↗

PubMed1993

Induction of axonal growth by heterophilic interactions between the cell surface recognition proteins F11 and Nr-CAM/Bravo.

F11 and Nr-CAM/Bravo are two axon-associated glycoproteins belonging to different subgroups of the immunoglobulin superfamily. In this report we have investigated the interaction of both proteins using neurite outgrowth and binding assays. Antibody blocking experiments demonstrate that neurite extension of tectal cells on immobilized F11 is mediated by Nr-CAM/Bravo. Binding studies further reveal a direct heterophilic interaction between F11 and Nr-CAM/Bravo. This activity can be mapped to the amino-terminal second or third immunoglobulin-like domain within F11 with domain-specific monoclonal antibodies and deletion mutant proteins expressed on COS cells. Furthermore, perturbation experiments with domain-specific monoclonal antibodies demonstrate that this region is required for adhesion and neurite extension.

Animals↗

PubMed1993

Cognitive function and spirometry performance in the elderly.

A total of 65 ambulatory subjects over the age of 65 yr were studied to determine if mild impairment in cognitive function precludes reliable spirometric measures in the aged. Standardized questionnaires were used to obtain information on demographics, cigarette smoking, respiratory symptoms, and physician-diagnosed lung disease. Each subject performed several simple standardized tasks of cognitive function and underwent spirometric testing. A total of 36 women and 29 men participated. The mean age for the group was 74.9 +/- 5.6 yr; most were nonsmokers (never smokers, n = 28; former smokers, n = 29; and current smokers, n = 8). Of the 65 participants, 8 (12.3%) individuals were unable to perform at least three ATS-acceptable FVC maneuvers after suitable demonstration. These subjects were similar to the 57 subjects able to perform three acceptable maneuvers, except for worse scores on both the symbol-digit modalities test (23.3 +/- 3.6 versus 31.6 +/- 10.5, p < 0.001) and the trail-making test, Part B (244.3 +/- 87.1 versus 160.4 +/- 71.8, p < 0.01). Of the 57 subjects able to perform spirometry, 18 (31.6%) failed to meet ATS reproducibility criteria for FEV1, FVC, or both. Cognitive impairment was not associated with the ability to achieve reproducible measures. These results suggest that the vast majority of older subjects can perform reliable spirometry; those elderly unable to perform spirometry may have impairment in cognitive function requiring further evaluation.

Aged↗

PubMed1992

Tandem translation of Bacillus subtilis initiation factor IF2 in E. coli. Over-expression of infBB.su in E. coli and purification of alpha- and beta-forms of IF2B.su.

The protein synthesis initiation factor, IF2, in Bacillus subtilis has previously been characterized as being present in two forms, alpha and beta, of molecular mass 79 and 68 kDa, respectively, on the basis of their cross-reaction with anti-E. coli IF2 antibodies and by the DNA sequence of the gene for IF2, infBB.su. In this work we have cloned infBB.su in E. coli cells. Two proteins of molecular mass identical to the B. subtilis IF2 alpha and -beta were over-expressed and purified using a new three-step ion-exchange chromatography procedure. The N-terminal amino acid sequence of the two proteins was determined and the results confirmed that the two forms were IF2 alpha and -beta, both encoded by the infB gene. The N-terminal amino acid sequence determined for IF2 beta is Met94-Gln-Asn-Asn-Gln-Phe. The presence of methionine at position 94 shows that this form is, in fact, the result of a second translational initiation in infBB.su mRNA, since the codon at amino acid position 94 is GUG, which is the normal codon for valine, but also known to be an initiator codon. This is a new example of the unusual tandem translation in E. coli of an open mRNA reading frame.

Amino Acid Sequence↗

PubMed1992

Evidence for the presence of complex high-molecular mass N-linked oligosaccharides in intranuclear glycoproteins from HeLa cells.

Nonhistone proteins were extracted in 0.4 M NaCl from membrane-depleted nuclei of HeLa cells grown in the presence or the absence of [5,6-3H]fucose. Control experiments strongly suggest that most extracted proteins were indeed nuclear components. Several proteins, present in the 0.4 M NaCl nuclear extract, with M(r) ranging from 35,000 to 115,000 were identified on Western blots as fucosylated glycoproteins owing to their binding to the fucose-specific lectin, Ulex europeus agglutinin I. Results of experiments involving mild alkaline treatment and peptide N-glycosidase F digestion showed that the carbohydrate moieties of these fucosylated nuclear glycoproteins were N-linked to the polypeptide backbone. Analysis of the N-glycans revealed the presence of two populations of sialylated oligosaccharides on the basis of their relative molecular masses. The sensitivity of the high-M(r) oligosaccharides to endo-beta-galactosidase and their incorporation of [3H]glucosamine suggest that they could contain repeating N-acetyllactosamine units. [3H]Fucose incorporated into nuclei was confined to the nucleoli, as judged by autoradiography of sections cut through cells grown in the presence of [3H]fucose. Electron microscopy autoradiography showed that the fibrillar centers were never labeled, while silver grains were observed on the dense and the granular components of nucleoli. Taking into account of these data most nuclear fucosylated glycoproteins extracted in 0.4 M NaCl might be nucleolar ribonucleoproteins.

Blotting, Western↗

PubMed1990

Analysis of nuclear sugar-binding components in undifferentiated and in vitro differentiated human promyelocytic leukemia cells (HL60).

The nuclear sugar-binding components (i.e., lectin-like molecules) were analyzed using isolated and membrane-depleted nuclei after incubation in the presence of fluorescein-labeled neoglycoproteins. This analysis was performed before and during the in vitro differentiation of HL60 cells into monocytes by PMA treatment and into granulocytes by DMSO treatment. The nucleoli of undifferentiated and differentiated HL60 cells were not labeled, unlike the nucleoli of other mammalian cells studied so far. This peculiarity allowed us to quantitatively analyze by flow cytometry the changes in the lectin activity associated with the extranucleolar territories enriched in ribonucleoprotein complexes. The neoglycoprotein binding was found to be significantly lower in differentiated than in undifferentiated cells. The decrease in neoglycoprotein binding was observed within the first 24 h of DMSO or PMA treatment, just before the arrest of DNA synthesis. Taking into account that the granulocytic differentiation required 72 h of chemical treatment, the extra-nucleolar lectins might be involved in modulation of the DNA synthesis rather than in phenotypic differentiation. These data are discussed in an attempt to reconcile the association of lectins with RNP complexes and their possible involvement in modulation of HL60 cell proliferation.

Carrier Proteins↗

PubMed1989

Simultaneous study of the pharmacokinetics of intravenous and oral nicardipine using a stable isotope.

The systemic elimination of nicardipine has been studied by an initial oral administration of nicardipine followed 1.25 h later by intravenous injection of the deuterium-labelled molecule (D3 nicardipine). To check that intravenous kinetics was not modified by the oral administration, an i.v. injection of unlabelled nicardipine (D0 nicardipine) was also given. The study was carried out in six healthy male volunteers, aged between 24 and 27 years, according to a Latin square cross-over design. Similar values were found for each kinetic parameter after i.v. administration regardless of whether it was administered alone by that route or with an oral dose. The plasma level-time curves of nicardipine were described by a three open compartment model. The total plasma clearance was about 800 ml/min, the volume of distribution was of the order of 1 l/kg and the half-life of beta-elimination ranged from 4 to 5 h. The elimination rate constant beta was independent of the route of administration.

Administration, Oral↗

PubMed1989

Stimulated production of ATP by H2O2 disproportionation in extracts from normal and xeroderma pigmentosum skins, and from normal, xeroderma pigmentosum, ataxia telangiectasia and simian virus 40 transformed cell lines.

It has been previously shown that xeroderma pigmentosum (XP) skin biopsies and their established cell lines exhibit a decrease in catalase activity and enhanced formation of photo-produced H2O2. Several in vivo and in vitro thermodynamic results suggest that the energy of H2O2 disproportionation produced by catalase could be sufficient to synthesize ATP with or without the help of intact mitochondria. In this paper, we first studied the properties of H2O2-stimulated ATP production in extracts of normal and pathological XP skin biopsies and cell lines. In acellular extracts of normal skin biopsies and/or cell lines, ATP production can be increased 2- to 3-fold, but only with a narrow range of H2O2 concentration. In contrast, in extracts of pathological skins or cells, ATP production was only observed when using 10- to 1000-fold less H2O2 concentration as defined for normal extracts. Similar results were noted with two cell lines derived from patients afflicted with ataxia telangiectasia (AT), and with simian virus 40 (SV40) transformed lines of normal, XP and AT cells, Although we have no proof that such a process may exist in vivo, we would like to suggest that both H2O2-stimulated ATP production and catalase activity are good indicators of the degree of normality or abnormality of skin biopsies and/or cell lines.

Adenosine Triphosphate↗

PubMed1988

The effect of acute hemiplegia on intercostal muscle activity.

We recorded the EMG of parasternal intercostal muscles in 25 patients with flaccid hemiplegia during quiet spontaneous breathing, voluntary hyperventilation, and CO2-induced hyperventilation. The respiratory drive was abnormal on the hemiplegic side and the function of the intercostal muscles was affected specifically during voluntary hyperventilation.

Acute Disease↗

PubMed1987

Study on the external fixator in the treatment of the fractures of the inferior end of the two bones of the adult's forearm. Report of fifty-five cases.

The authors report 55 cases of fracture with significant displacement of the distal end of the radius. In 30 cases, there were, moreover, lesions of adjacent bones and in 18 cases, lesions of the soft tissues. The fractures were treated by Hoffmann external fixator placed either immediately or later on, after the failure of conservative treatment. Thirty-four cases, reexamined within a period of at least six months, were used to show the results according to the criteria of Castaing. The overall results show 3 perfect results, 23 satisfactory ones and 8 quite satisfactory. The main complication of this series is frequent algodystrophy in the first cases. This has practically disappeared since much less traction is applied to the fracture site.

Adult↗

PubMed1986

Deficiency in the catalase activity of xeroderma pigmentosum cell and simian virus 40-transformed human cell extracts.

It has been previously shown that skin biopsies isolated from various xeroderma pigmentosum (XP) patients present a permanent decline in catalase activity from the onset of the disease to the tumor formation. We report here that cultured XP cell strains are also markedly deficient in the catalase activity with about only 25% of the activity measured in normal human cells. No direct correlation between catalatic activity and excision repair ability has been found, since a XP variant line is as deficient as an XP-C strain. The exact cause of the catalase deficiency is still unknown but could be due to the synthesis of a modified enzyme or to an abnormal regulation leading to a limited enzyme synthesis. Furthermore, simian virus 40 transformation of normal and radiosensitive cells (XP, ataxia telangiectasia) provokes a decrease in catalase activity of about 80% compared to the control derivatives. Mathematical analysis performed on our data shows a clearcut distinction between XP and normal cells while some of the XP heterozygote cells exhibit an intermediate behavior. Although most of the XP syndrome could be explained by the impairment in the excision repair ability, the decrease in catalase activity leading to a probable increase in intracellular H2O2 concentration and/or to a higher sensitivity to any oxygen-activated species could represent an additive effect in inducing the carcinogenic process.

Acatalasia↗