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T Braun

Publications and source records attributed to T Braun.

At least 109 records · Page 6Linked to original sources
PubMed1990

Identification of three developmentally controlled isoforms of human myosin heavy chains.

A set of cDNA clones coding for myosin heavy chains (MHC) was isolated from a human fetal skeletal muscle library. We have demonstrated by restriction mapping and nucleotide sequence analysis that the cDNAs represent three distinct transcripts, presumably the products of different genes. Furthermore, the pattern of mRNA expression indicates that the corresponding genes are regulated in a tissue-specific and developmental-stage-specific manner. While the cDNA clone gtMHC-V exhibits extensive sequence similarity to the rat beta-myosin heavy chain, the two other clones, gtMHC-F and gtMHC-E are very similar to the rat genes encoding the perinatal and embryonic myosin heavy chains, respectively. The mRNA corresponding to clone gt-MHC-V is highly expressed in heart and adult fast skeletal muscle and to a lesser extent in fetal skeletal muscle and adult slow skeletal muscle. The mRNAs corresponding to clones gtMHC-F and gtMHC-E are abundantly present in fetal skeletal muscle and are not present or barely detectable in heart and adult skeletal muscle.

Adult↗
PubMed1990

Myf-6, a new member of the human gene family of myogenic determination factors: evidence for a gene cluster on chromosome 12.

The Myf-6 gene, a novel member of the human gene family of muscle determination factors has been detected by its highly conserved sequence coding for a putative helix-loop-helix domain. This sequence motif is a common feature of all Myf factors and other regulatory proteins. The new Myf gene is located on human chromosome 12, approximately 6.5 Kb upstream of the Myf-5 locus in a closely linked cluster of myogenic determination genes. Myf-6 cDNAs were isolated from human and mouse skeletal muscle, the only tissue in which expression of the corresponding mRNA was observed. In contrast to human primary muscle cell cultures which express moderate levels of Myf-6 mRNA, most established rodent muscle cell lines completely lack this mRNA. Myogenic 10T1/2 cells, however, induced by the expression of either pEMSV-Myf-4 or pEMSV-Myf-5 activate their endogenous mouse Myf-6 gene. Constitutive expression of Myf-6 cDNA in C3H 10T1/2 fibroblasts establishes the muscle phenotype at a similar frequency to the previously characterized myogenic factors. Moreover, muscle-specific CAT reporter constructs containing either the human myosin light chain (MLC) enhancer or the promoter of the embryonic myosin light chain gene are activated in NIH 3T3 fibroblasts or in CV1 kidney cells by cotransfection of Myf-6 expression vehicles. This transcriptional activation occurs in the absence of any apparent conversion of the cellular phenotype of the recipient cells. Glutathione-S-transferase fusion proteins with Myf-3, Myf-4 or Myf-5 specifically bind to a MEF-like consensus sequence present in the human MLC enhancer and the MLC1 emb promoter. In contrast, the Myf-6 hybrid protein interacts weakly with the same sequences showing lower affinity and reduced specificity. Since co-expressed pEMSV-Myf-6, nevertheless, is able to activate transcription of the MLC-CAT reporter constructs in non-muscle tissue culture cells, the different DNA binding properties in vitro might suggest that transactivation of gene expression by Myf-6 involves distinct binding sites and/or additional protein factors.

Amino Acid Sequence↗
PubMed1990

The human MyoD1 (MYF3) gene maps on the short arm of chromosome 11 but is not associated with the WAGR locus or the region for the Beckwith-Wiedemann syndrome.

The human gene encoding the myogenic determination factor myf3 (mouse MyoD1) has been mapped to the short arm of chromosome 11. Analysis of several somatic cell hybrids containing various derivatives with deletions or translocations revealed that the human MyoD (MYF3) gene is not associated with the WAGR locus at chromosomal band 11p13 nor with the loss of the heterozygosity region at 11p15.5 related to the Beckwith-Wiedemann syndrome. Subregional mapping by in situ hybridization with an myf3 specific probe shows that the gene resides at the chromosomal band 11p14, possibly at 11p14.3.

Animals↗
PubMed1990

The testicular receptor for follicle stimulating hormone: structure and functional expression of cloned cDNA.

Cloned cDNA encoding the rat Sertoli cell receptor for FSH was isolated from a cognate library and functionally expressed in cultured mammalian cells. The FSH receptor (FSH-R), as predicted from the cDNA, is a single 75K polypeptide with a 348 residue extracellular domain which contains three N-linked glycosylation sites. This domain is connected to a structure containing seven putative transmembrane segments which displays sequence similarity to G protein-coupled receptors. Thus, the FSH-R is identical in its structural design to the LH/CG receptor (LH/CG-R). Furthermore, both receptors display 50% sequence similarity in their large extracellular domains and 80% identity across the seven transmembrane segments. Expression of the cloned cDNA in mammalian cells conferred FSH-dependent cAMP accumulation. The selectivity for FSH is attested by the fact that the related human glycoprotein hormones human CG and human TSH do not stimulate adenylyl cyclase in FSH-R expressing cells even when these hormones are present at high concentrations.

Adenylyl Cyclases↗
PubMed1990

Inhibition of the soluble form of testis adenylate cyclase by catechol estrogens and other catechols.

The soluble form of rat germ cell adenylate cyclase was inhibited by compounds with a catechol moiety. Among the naturally occurring catechols tested, catechol estrogens were the most potent inhibitors. Catechol estrogens at 2-6 microM inhibited enzyme activity by 50% and almost completely at 30-100 microM concentration. The inhibitory activity of catechol estrogens depends on the catechol moiety of the molecule. Catechol per se also inhibited the activity of this enzyme, 50% inhibition being achieved at about 11 microM. The two hydroxyls of the catechol moiety are essential for the inhibitory interaction with the enzyme. Thus, aromatic compounds containing only one hydroxyl group in the benzene ring, such as tyrosine, phenylephrine, estradiol, and 6 alpha-hydroxyestradiol were either completely inactive or had marginal inhibitory activity at concentrations up to 0.3-1 mM. Moreover, methylation of the hydroxyl groups of the catechol moiety of the catechol estrogens as in 2-methoxyestradiol 3-methyl ether rendered the catechol estrogens inactive. The inhibitory potency of these compounds varied greatly depending on the structure associated with the catechol ring. Thus, compounds in which catechol is associated with an aliphatic side chain, such as dopamine, L-dopa, norepinephrine, and isoproterenol, were about 11- to 34-fold less potent than catechol. On the other hand, compounds in which catechol is associated either with a hydroaromatic ring system, as in apomorphine, or with an alicyclic ring system, as in catechol estrogens, were about 2- to 5-fold more potent than catechol. The inhibitory effect of dopamine, apomorphine, and catechol estrogens was not affected by specific D-1 or D-2 antagonist, indicating that they do not act via receptors for dopamine.

Adenylyl Cyclase Inhibitors↗
PubMed1989

Differential expression of myogenic determination genes in muscle cells: possible autoactivation by the Myf gene products.

The development of muscle cells involves the action of myogenic determination factors. In this report, we show that human skeletal muscle tissue contains, besides the previously described Myf-5, two additional factors Myf-3 and Myf-4 which represent the human homologues of the rodent proteins MyoD1 and myogenin. The genes encoding Myf-3, Myf-4 and Myf-5 are located on human chromosomes 11, 1, and 12 respectively. Constitutive expression of a single factor is sufficient to convert mouse C3H 10T1/2 fibroblasts to phenotypically normal muscle cells. The myogenic conversion of 10T1/2 fibroblasts results in the activation of the endogenous MyoD1 and Myf-4 (myogenin) genes. This observation suggests that the expression of Myf proteins leads to positive autoregulation of the members of the Myf gene family. Individual myogenic colonies derived from MCA C115 cells (10T1/2 fibroblast transformed by methylcholanthrene) express various levels of endogenous MyoD1 mRNA ranging from nearly zero to high levels. The Myf-5 gene was generally not activated in 10T1/2 derived myogenic cell lines but was expressed in some MCA myoblasts. In primary human muscle cells Myf-3 and Myf-4 mRNA but very little Myf-5 mRNA is expressed. In mouse C2 and P2 muscle cell lines MyoD1 is abundantly synthesized together with myogenin. In contrast, the rat muscle lines L8 and L6 and the mouse BC3H1 cells express primarily myogenin and low levels of Myf-5 but no MyoD1. Myf-4 (myogenin) mRNA is present in all muscle cell lines at the onset of differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1989

A novel human muscle factor related to but distinct from MyoD1 induces myogenic conversion in 10T1/2 fibroblasts.

We have isolated the cDNA encoding a novel human myogenic factor, Myf-5, by weak cross-hydridization to the mouse MyoD1 probe. Nucleotide sequence analysis and the identification of the corresponding gene indicate that human Myf-5 is a member of a small gene family which also contains the human homologue to MyoD1. Although structurally related to the mouse factor, the human Myf-5 constitutes a different protein which nevertheless is capable of inducing the myogenic phenotype in embryonic C3H mouse 10T1/2 'fibroblasts'. The existence of more than one MyoD1-like protein in human skeletal muscle is further suggested by the detection of several similar but distinct cDNA clones. The phenotypic conversion of 10T1/2 cells by the human factor is recognized by the capacity of the cells to form multinucleated syncytia and synthesize sarcomeric myosin heavy chains. Moreover, transient expression of Myf-5 in 10T1/2 cells leads to the activation of a co-transfected muscle-specific CAT reporter gene which by itself is transcriptionally silent in the non-muscle cell background. The deduced amino acid sequence of clone Myf-5 reveals a region which is highly similar to myc proteins and the developmental factors from Drosophila encoded by the achaete scute locus and the twist gene. The myc homology region and a preceding cluster of basic amino acids are located in a larger sequence domain with strong similarity to the mouse myogenic factor MyoD1. Two additional short segments with high serine and threonine content are conserved between the two proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1989

Promoter upstream elements of the chicken cardiac myosin light-chain 2-A gene interact with trans-acting regulatory factors for muscle-specific transcription.

A segment of the 5'-flanking region of the chicken cardiac myosin light-chain gene extending from nucleotide -64 to the RNA start site is sufficient to allow muscle-specific transcription. In this paper, we characterize, by mutational analysis, sequence elements which are essential for the promoter activity. Furthermore, we present evidence for a negative-acting element which is possibly involved in conferring the muscle specificity. Nuclear proteins specifically bind to the DNA elements, as demonstrated by gel mobility shift assays and DNase I protection footprinting. The significance of the DNA-protein interactions for the function of the promoter in vivo is demonstrated by competition experiments in which protein-binding oligonucleotides were microinjected into nuclei of myotubes, where they successfully competed for the protein factors which are required to trans activate the MLC2-A promoter. The ability to bind nuclear proteins involves two closely spaced AT-rich sequence elements, one of which constitutes the TATA box. The binding properties correlate well with the capacity to activate transcription in vivo, since mutations in this region of the promoter concomitantly lead to loss of binding and transcriptional activity.

Animals↗
PubMed1988

The interaction of nuclear proteins with essential promoter element of the chicken cardiac myosin light chain 2 gene is involved in muscle-specific transcription.

A quantitative microinjection procedure has been developed to demonstrate muscle-specific transcription of the myosin light chain 2-A (MLC2-A) promoter in differentiated chicken primary breast muscle cells. Nuclear protein binds to the distal region of the required promoter sequence but not to a mutated version of this sequence. The functional significance of this specific DNA-protein interaction for the promoter activity is demonstrated by 'in vivo' competition of microinjected MLC-CAT reporter construct together with excess of synthetic oligonucleotides encompassing the protein binding sites.

Animals↗
PubMed1988

Systemic joint laxity (the hypermobile joint syndrome) is associated with temporomandibular joint dysfunction.

A consecutive series of 37 individuals admitted to the hospital for elective temporomandibular joint (TMJ) reconstructive surgery and 3 seen as outpatients with TMJ disease were evaluated for rheumatic disease or for another etiologic factor that might account for this problem. These 40 patients were screened by history, physical examination, and laboratory study. We soon noticed that many patients had generalized joint laxity. Eighteen of the first 40 individuals satisfied established criteria for the hypermobile joint syndrome. An additional 3 were found to have Ehlers-Danlos syndrome or a forme fruste of this disorder. Many were markedly hypermobile and could perform a number of flexible maneuvers. Although excessive joint laxity is known to be associated with a variety of rheumatic conditions, TMJ disease has not been recognized as one of them. No patient in this series had a systemic inflammatory disorder or any other apparent etiologic factor for TMJ disease. We suggest that there is a cause-and-effect relationship between generalized joint laxity and TMJ disease.

Adolescent↗
PubMed1988

The classification of ethnic status using name information.

Methodology is developed to classify ethnic status by name using a simple probabilistic model. This method involves the consideration of four rules which may be used to classify individuals using three name components (first, middle and last names). In order to do this, conditional probabilities of ethnic status are estimated from a sample in which the ethnic status is known. Using a split sample technique the sensitivity and specificity of this methodology were examined in a data set of death registrations. Each of the classification rules performed well on the data from which they were constructed but were not as efficient when applied to another population. Nevertheless a model (linear), in which the sum of the conditional probabilities of each home component is used, achieved a sensitivity and specificity of 97% and 100% respectively in males and 89% and 100% in females.

Canada↗
PubMed1988

Dimensional changes of the feet in pregnancy.

Serial measurements of the volume, length, and width of the feet of seventeen pregnant women were made at, or close to, the thirteenth and thirty-fifth weeks of pregnancy and eight weeks postpartum. The same measurements were made twice on a control group of sixteen nulliparous women at intervals that ranged from sixteen to twenty weeks. There was no change in the length or width of the feet in either group. The mean volume of the feet increased 57.2 milliliters between early and late pregnancy (p less than 0.001) and decreased by only 8.42 milliliters between late pregnancy and eight weeks postpartum. These changes were attributed to retention of fluid or to an increase in soft tissue and not to stretching or relaxation of the ligaments.

Adult↗
PubMed1987

A novel subtype of muscarinic receptor identified by homology screening.

A new member of the protein superfamily of G-protein coupled receptors has been isolated by homology screening. By virtue of its homology with other muscarinic acetylcholine receptors and its ability to bind muscarinic specific antagonists, this muscarinic receptor subtype is designated M4. The M4 mRNA is preferentially expressed in certain brain regions. The existence of multiple receptor subtypes encoded by distinct genes in the brain has functional implications for the molecular mechanisms underlying information transmission in neuronal networks.

Amino Acid Sequence↗
PubMed1987

Characterization of the purine-reactive site of the rat testis cytosolic adenylate cyclase.

Naturally soluble rat germ cell adenylate cyclase was inhibited by adenosine and the adenosine analogs, 9-beta-D-arabinofuranosyl adenine (AFA) and 2',5'-dideoxyadenosine (DDA), all of which inhibited hormone-sensitive adenylate cyclases at the "P" site. The IC50 values for adenosine and DDA were approximately 0.1 and for AFA, 4.0 mM. The onset of adenosine inhibition was very rapid whether adenosine was added to the enzyme reactant mixture at time zero concomitantly with the addition of substrate or after the enzyme had been activated by the addition of substrate. The adenosine analogs, N6-methyladenosine (MeA) and N6-phenylisopropyl adenosine (PIA), which interact with plasma membrane receptors ("R" receptors) for hormone-sensitive adenylate cyclase, had little effect on the activity of the cytosolic adenylate cyclase. Additionally, aminophylline, which has been shown to competitively antagonize adenosine interactions with the plasma membrane "R" receptors but not "P" site interactions, had no effect upon substrate activation of the soluble enzyme and did not prevent adenosine from inhibiting the activity of the enzyme. These data provide evidence for an adenosine regulatory site on the cytosolic enzyme which resembles the "P" site described for membrane bound-adenylate cyclase.

Adenosine↗
PubMed1987

The dopamine D-2 antagonist, Ro 22-1319, inhibits the persistent behavioral syndrome induced by iminodipropionitrile (IDPN) in mice.

Chronic administration of beta,beta'-iminodipropionitrile causes a persistent syndrome of excitement, choreoathetoid movements, and circling (the "ECC-syndrome") which persists indefinitely after termination of the IDPN injections. Ro 22-1319 is a specific D-2 dopamine receptor antagonist which was recently synthesized to fit a hypothetical model of the D-2 receptor. Ro 22-1319 inhibited several aspects of the ECC-syndrome, although some of its components, such as backward pedaling and forepaw treading reminiscent of the serotonin syndrome, were exacerbated. These results suggest that several neurotransmitter systems may be involved in the ECC-syndrome.

Animals↗