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Biomedical subjects

J Perret

Publications and source records attributed to J Perret.

At least 55 records · Page 3Linked to original sources
PubMed1992

Composition and immunogenicity of the polysaccharide components of the thermostable macromolecular antigen group of mycobacterial antigens.

The thermostable macromolecular antigen (TMA) group includes major components of the mycobacterial cell envelope and cytoplasm, which elicit humoral and cellular immune reactions, and seems to play important roles in infectious diseases. The best known member of this group, antigen A60 of Mycobacterium bovis BCG, was previously shown to contain three moieties of polysaccharides, free lipids, and polypeptides. In this work, the TMA polysaccharides of three pathogenic mycobacteria (M. avium, M. bovis and M. paratuberculosis) have been analyzed by coupled gas chromatography-mass spectrometry. In all cases the cores of the TMA complexes were represented by branched glucans of high molecular mass (about 10(6) daltons), for which structural models have been proposed. The immunogenicity of the polysaccharide components from the three TMA was verified with several immunological procedures (immunodiffusion and immunoelectrophoresis of the antigen, and immunoblotting of the corresponding electrofocused immunoglobulins). All tests tallied in showing a negligible immunogenicity of the glucans examined (inability to produce, upon injection, the synthesis of specific immunoglobulins), thus pointing to the protein moiety of TMA as the one responsible for the high immunoreactivity of the complexes.

Animals↗
PubMed1992

Recombinant TSH-receptor for determination of TSH-receptor-antibodies.

We have expressed the complete coding sequence of the human TSH-R in eucaryotic cells. Limiting dilution enabled us to select two clones, JP09 and JP26, which have formed the basis of binding and bioassays respectively, for TSH-R antibodies. Results obtained in the binding assay correlated well with those obtained in the TRAK (Henning Berlin) assay, while the bioassay was at least as sensitive as measurements made with FRTL5 or human thyroid cells. These cell lines provide a reliable source of human TSH-R which will be useful in routine diagnosis.

Animals↗
PubMed1992

Relationship between levodopa-independent symptoms and central atrophy evaluated by magnetic resonance imaging in Parkinson's disease.

Thirty patients with Parkinson's disease were studied for the purpose of investigation relations between motor symptoms and cerebral atrophy evaluated by magnetic resonance imaging (MRI). Axial symptoms (gait disorder, postural instability and difficulty in arising from a chair), assessed at the time of maximum clinical improvement, were significantly correlated with frontal atrophy, while no correlation was found between the basal parkinsonian disability score and cerebral atrophy. It is suggested that frontal atrophy observed by MRI is linked with axial motor symptoms resulting from non-dopaminergic lesions. The origin of this atrophy is unknown.

Aged↗
PubMed1992

[Treatment of spasticity with botulinum toxin].

Spasticity following upper motor neuron lesion can be alleviated by few treatments such as physiotherapy, drugs and neurosurgery. However, they all have side effects, limitations or lack of selectivity. We tentatively used the paralyzing effects of botulinum toxin. Since the late 1970's the use of this toxin has increased and it has been extended to numerous muscles and diseases of various causes. In this pilot and open study we use botulinum toxin in spasticity. Eight patients (7 stroke, 1 head injury) with longstanding severe spasticity (minimum: 12 months, maximum: 15 years) were included. Spasticity greatly interfered with their activity in daily life and was resistant to oral antispastic medications. Six patients suffered from pain and 4 had cutaneous lesions especially maceration of the palm of the hand. A-botulinum toxin was injected with a 30-gauged needle. The sites chosen for injection were the following muscles: biceps brachii, brachioradialis, flexor digitorum, flexor carpi, tibialis anterior, flexor digitorum longus. Altogether 41 injections were performed. There were no side effects. Spasticity was improved in all patients. Five patients reported significant pain relief on a visual analogical scale. Most of them reported a benefit in their limb tone and referred to subjective improvement in the activity of daily life and nursing. The beneficial effects of one injection lasted more than 5 months. Seven patients received a second course of treatment. A double-blind study of botulinum toxin in spasticity is to be undertaken to assess its effectiveness and safety when prescribed in the required dose to treat this condition.

Adult↗
PubMed1991

Molecular cloning and expression of a new putative inositol 1,4,5-trisphosphate 3-kinase isoenzyme.

A human hippocampus cDNA library in lambda ZAP II was screened by hybridization with a rat brain inositol 1,4,5-trisphosphate (InsP3) 3-kinase cDNA. Two clones (hh6 and hh3) were isolated and sequenced. The insert of clone hh6 was shown to correspond to the 3' end of the coding sequence of 50,000-Mr InsP3 3-kinase (referred to as 3-kinase-A). Sequencing of the clone hh3 insert yielded an open reading frame encoding a 472-amino acid protein with a calculated Mr of 53,451 (referred to as 3-kinase-B). The C-terminal part of 3-kinase-B (residues 187-462) was 68% identical with 3-kinase-A in amino acid sequence. The cDNA of clone hh3 was rescued as a Bluescript plasmid and expressed in Escherichia coli as a beta-galactosidase fusion product. It showed InsP3 3-kinase activity that was stimulated in the presence of Ca2+/calmodulin (more than 7-fold in a crude bacterial lysate from expressed plasmid). Regeneration of InsP3 3-kinase activity after SDS/PAGE identified a major polypeptide (Mr 60,000-65,000). The Km for InsP3 of expressed 3-kinase-B was 1.6 microM. These data provide molecular evidence for the existence of InsP3 3-kinase isoenzymes.

Amino Acid Sequence↗
PubMed1991

Molecular cloning and expression of a human brain inositol 1,4,5-trisphosphate 3-kinase.

A human hippocampus cDNA library was screened by hybridization with a rat brain inositol 1,4,5-trisphosphate (InsP3) 3-kinase cDNA. Sequencing of three overlapping clones identified a 1383 bp open reading frame encoding a 461 amino acid protein with a calculated molecular weight of 50988. The coding amino acid sequence showed an overall 93% similarity with the sequence of rat brain InsP3 3-kinase. The cDNA insert of one isolated partial clone (i.e. hh 26) was in frame with the beta galactosidase fragment fused to it as a Bluescript plasmid; it displayed InsP3 3-kinase activity when expressed in Escherichia coli (E. coli). Biochemical characterization of human brain InsP3 3-kinase by SDS polyacrylamide gel electrophoresis and regeneration of enzyme activity reveals three active fractions with apparent Mr of 58,000-64,000, 45,000-50,000 and 37,000-39,000.

Amino Acid Sequence↗
PubMed1991

Antibody to reverse transcriptase of human retroviruses in multiple sclerosis.

HTLV-1, HIV-1 and HIV-2 western blot analysis of sera from patients with multiple sclerosis (MS), from patients with other neurological diseases and from blood donors, revealed a rather frequent cross-reactivity with retroviral proteins in the MS group, though no patient was positive with the corresponding specific ELISA serology. Statistical analysis revealed a significant difference between the MS group and the two control groups for HIV-1 and HIV-2 reverse transcriptase fragments and for HTLV-1 p24. The general significance of these observations is discussed in the light of a retroviral hypothesis for the aetiology of MS. It is suggested that, if a retrovirus is present in MS patients, it does not necessarily belong to the HTLV sub-family and could as well be a lentivirus, like Visna virus, the causative agent of a demyelinating disease in sheep which is one--natural--model for MS.

AIDS Serodiagnosis↗
PubMed1991

A 3' splice site mutation in the thyroglobulin gene responsible for congenital goiter with hypothyroidism.

A case of congenital goiter with defective thyroglobulin synthesis has been studied in molecular terms. The patient is the fifth of a kindred of six, three of which have a goiter. The parents are first cousins. Segregation of thyroglobulin alleles in the family was studied by Southern blotting with a probe revealing a diallelic restriction fragment length polymorphism (RFLP). The results demonstrated that the three affected siblings were homozygous for the RFLP. Northern blotting analysis of the goiter RNA with a thyroglobulin probe suggested that thyroglobulin mRNA size was slightly reduced. Polymerase chain reaction amplification of the 8.5-kb thyroglobulin mRNA as overlapping cDNA fragments demonstrated that a 200-bp segment was missing from the 5' region of the goiter mRNA. Subcloning and sequencing of the cDNA fragments, and of the patient genomic DNA amplified from this region, revealed that exon 4 is missing from the major thyroglobulin transcript in the goiter, and that this aberrant splicing is due to a C to G transversion at position minus 3 in the acceptor splice site of intron 3. The presence in exon 4 of a putative donor tyrosine residue (Tyrosine nr 130) involved in thyroid hormone formation provides a coherent explanation to the hypothyroid status of the patient.

Adult↗
PubMed1990

Thyrotropin activates both the cyclic AMP and the PIP2 cascades in CHO cells expressing the human cDNA of TSH receptor.

The effect of thyrotropin (TSH) on cyclic AMP accumulation, phosphatidylinositol bisphosphate (PIP2) hydrolysis and [Ca2+]i rise has been studied in CHO cells stably transfected with human TSH receptor (hTSHR) cDNA. In human thyroid slices, TSH activates these two intracellular cascades with a higher affinity for the adenylate cyclase activation (from 0.1 to 1 mU/ml TSH) than for phospholipase C activation (from 1 to 10 mU/ml TSH). The CHO cells transfected with the recently cloned cDNA of human TSH receptor respond in the same way to TSH. They respond between 0.1 and 1 mU/ml TSH for cyclic AMP accumulation and between 1 and 10 mU/ml TSH for inositol monophosphate (IP1) increase. In these same cells, TSH 10 mU/ml, but not forskolin (10 microM), or dibutyryl cyclic AMP (100 microM), clearly enhances intracellular calcium concentration [( Ca2+]i). Our results demonstrate unequivocally that a single transcription unit has the potential to encode receptor molecules coupled to both cascades.

Adenylyl Cyclases↗
PubMed1990

Use of the recombinant human thyrotropin receptor (TSH-R) expressed in mammalian cell lines to assay TSH-R autoantibodies.

We report on two assays for autoantibodies to the TSH-R which have been developed using materials from mammalian cells transfected with the cDNA for the human TSH-R. In the first, a particulate fraction has been prepared from COS cells, transiently expressing the human TSH-R and used in a radioreceptor assay in conjunction with bovine 125I-TSH. Immunoglobulins (IgGs) from patients with Graves' disease (n = 11) and idiopathic myxoedema (n = 2) have been used as competitors of 125I-TSH binding to the COS TSH-R membranes and the results have been compared with those obtained with a commercially available kit for measuring TSH-R autoantibodies, which uses solubilised porcine TSH-R. Both assays showed similar performance, being particularly sensitive to antibodies from patients with idiopathic myxoedema. In the second assay system we have used a CHO cloned cell line (JP26) stably transfected with the human TSH-R. A selection of IgG preparations from patients with Graves' disease and of six normal controls was used to test the ability of this cell line to detect thyroid stimulating immunoglobulins (TSAb) by increasing its cAMP production. The assay was performed under two conditions: in standard (isotonic) medium or in hypotonic medium. Freshly thawed human thyrocytes incubated in hypotonic medium served as a reference method. Only five patients scored positive when tested in the JP26 cell line under isotonic conditions. When the assay was performed in a hypotonic medium, a significant positive correlation was observed between the results given by JP26 cells and human thyrocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Stable expression of the human TSH receptor in CHO cells and characterization of differentially expressing clones.

The human thyrotropin receptor cDNA was transfected in CHO cells and individual clones were isolated. They were tested for their response to thyrotropin, forskolin and antibodies from a patient with high levels of thyroid stimulating antibodies. Several clones were characterized extensively with respect to membrane binding of labeled thyrotropin, cAMP accumulation in response to thyrotropin and kinetics of cAMP production. Data for three representative clones are presented. Receptor number as assessed by membrane binding of labeled thyrotropin, and cAMP production, measured in a thyrotropin response bioassay, are correlated. The Kd value for the human thyrotropin receptor expressed in CHO was estimated to be 50 pM.

Animals↗
PubMed1990

[Vascular accidents of the brain stem].

Cerebrovascular accidents (CVA's) of the brain stem have the same causes and physiopathological mechanisms as CVA's of the hemispheres, but they are ten times less frequent. They correspond to ischaemic or haemorrhagic lesions in the territories of the vertebral arteries and the basilar artery, including their collateral, circumferential and perforating branches. Clinically, CVA's of the brain stem are characterized by the association of unilateral motor and/or somatosensory symptoms on the side opposite the lesion, and by involvement of the ipsilateral cranial nerves, which helps in evaluating the level of the CVA. Motor or somatosensory symptoms may be bilateral or on alternate sides. The complexity of these CVA's reflects the rich anatomical organization of the brain stem. Their severity in case of extensive lesions is due to the fact that they affect structures that are vital to consciousness and cardiorespiratory regulation. Patients with CVA's of the brain stem must be hospitalized in neurology departments.

Brain Stem↗
PubMed1990

Molecular cloning of a dog thyrotropin (TSH) receptor variant.

A clone coding for a variant form of thyrotropin receptor was isolated from a dog thyroid cDNA library. It was characterized by a 75 bp deletion in the coding region, additionally to minor modifications in the 3' untranslated region. The corresponding 25 amino acids deletion is located in the long NH2 terminal extracellular domain which is characteristic of the glycoprotein hormone receptors. This region of the protein is composed of imperfect repeats and the deletion corresponds exactly to one of the repeat units. This suggests that the repeats correspond to individual exons in the thyrotropin receptor chromosomal gene. It is not known whether the deletion of the repeat and the concomitant suppression of one of the N-glycosylation sites of the molecule do alter the receptor function.

Amino Acid Sequence↗
PubMed1990

Effects of passive tactile and auditory stimuli on left visual neglect.

Patients with left-sided visual neglect fail to copy the left part of drawings or the drawings on the left side of a sheet of paper. Our aim was to study the variations in copying drawings induced by passive stimulation in patients with left-sided visual neglect. No stimulation at all, tactile unilateral and bilateral, binaural auditory verbal, and nonverbal stimuli were randomly applied to 14 patients with right-hemisphere strokes. Only nonverbal stimuli decreased the neglect. As nonverbal stimuli mainly activate the right hemisphere, the decrease in neglect suggests right-hemispheric hypoactivity at rest in these patients. The absence of modification of neglect during verbal stimulation suggests a bilateral hemispheric activation and the persistence of interhemispheric imbalance. Our results showed that auditory pathways take part in the network involved with neglect. Passive nonverbal auditory stimuli may be of interest in the rehabilitation of patients with left visual neglect.

Acoustic Stimulation↗