Biomedical subjects

S Ruppert

Publications and source records attributed to S Ruppert.

46 records · Page 3Linked to original sources

PubMed1988

[Successful antibiotic treatment of a pulmonary infection with Nocardia asteroides (biovariety A3)].

An open lung biopsy in a 67-year-old man revealed nocardiosis as the cause of a treatment-resistant pulmonary infection. His resistance had been weakened by a non-Hodgkin lymphoma, polychemotherapy and long-term steroid medication. The nocardiosis was cured by a 26-day high-dosage regimen of imipenem and amikacin in combination. A six-month period of co-trimoxazole followed to ensure treatment success. Nocardia asteroides (biovariety A3) was found to be the causative organism, the second time that this has been described as cause of a human infection.

Aged↗

PubMed1988

Multiple transcripts of the mouse tyrosinase gene are generated by alternative splicing.

We report the cloning and isolation of the mouse tyrosinase cDNA by screening mouse B16 melanoma cDNA libraries. Independent cDNA clones have been characterized by restriction enzyme analysis, hybridizations with individual subprobes and by partial sequencing analysis. Based on these criteria we have identified multiple transcripts, which in comparison to the major transcript, display deletions of internal sequences and have different 3' termini. The most abundant transcript encodes a functional tyrosinase. The structural gene which encodes five exons separated by large introns and spans a chromosomal region of approximately 70 kb has been isolated. Comparison of the cDNAs with the cloned genomic DNAs and sequencing of the exon/intron boundaries reveal that the multiple transcripts are generated by alternative splicing and putatively by alternate polyadenylation site usage. The alternative splicing mechanisms involve exon skipping as well as internal donor splice site usage. Primer extension analysis shows that the transcripts are produced from two different promoters. Southern blot analysis of DNAs derived from mice carrying the lethal albino deletion mutations demonstrates that the structural gene maps near or at the albino locus. The viable albino mouse BALB/c carries an apparently intact structural gene indicating that the albino phenotype is a consequence of a failure to express the tyrosinase gene or the inability to produce a tyrosinase enzyme.

Animals↗

PubMed1988

Functional analysis of alternatively spliced tyrosinase gene transcripts.

Three different cDNA clones (pmcTyr1, pmcTyr2 and pmcTyr3) representing mRNAs originating by alternative splicing of the primary transcript of mouse tyrosinase gene, were identified and characterized by sequence analysis and by a functional assay. These cDNAs were subcloned into the newly constructed expression vector pHD. After electroporation of these hybrid clones into tyrosinase negative cells, protein extracts were prepared and tested for tyrosinase enzyme activity. Only the cDNA insert of pmcTyr1 was able to confer tyrosinase enzyme activity. This cDNA encodes a protein 533 amino acid residues in length containing a putative leader peptide of 18 amino acids and six putative glycosylation sites. Comparisons of the deduced amino acid sequence of the cDNA clone pmcTyr1 with the protein sequence of tyrosinases from man, Streptomyces, Neurospora and with haemocyanin subunits from a spider showed two regions of sequence conservation. One of these regions is known to be involved in copper binding. Since this gene with the coding capacity for tyrosinase is absent in all studied c-locus lethal deletion mutant mice, we have evidence that albinism in mice is caused by mutations of the tyrosinase gene.

Amino Acid Sequence↗

PubMed1987

Genomic footprinting reveals cell type-specific DNA binding of ubiquitous factors.

Using in vivo dimethylsulfate footprinting, we have analyzed protein-DNA interactions within two regions upstream of the tyrosine aminotransferase (TAT) gene that are characterized by an altered chromatin structure in TAT-expressing as compared to nonexpressing cells. All the identified protein contacts to DNA are found exclusively in the TAT-expressing hepatoma cells. In vitro analyses of specific DNA-binding factors in crude nuclear extracts yield DNAase I footprints that correlate well with the binding sites in vivo. Surprisingly, all DNA-binding activities are present in nuclei of TAT-expressing and nonexpressing cells, indicating that the mere presence of factors is not sufficient for their interaction with a binding site in vivo. Genomic sequencing reveals methylation of CpG dinucleotides in the regions analyzed in nonexpressing cells, whereas no methylation is found in TAT-expressing cells. In vitro methylation at a cytosine residue within a footprint region prevents the interaction of a factor with its binding site.

Animals↗

PubMed1985

Isolation, characterization and chromosomal mapping of the mouse tyrosine aminotransferase gene.

The tyrosine aminotransferase (TAT) gene is expressed in a tissue and developmental-specific manner. In addition, this gene is regulated by glucocorticoid and polypeptide hormones and its expression is affected when a regulatory region near the albino locus of the mouse is deleted. In order to allow studies of the molecular effects of these deletion mutations we have isolated and characterized the mouse TAT gene. The gene is 9.2 x 10(3) bases in length and consists of 12 exons which give rise to a 2.3 x 10(3) base long messenger RNA. The DNA sequence at the 5' end of the gene was determined and compared with the corresponding sequence of the rat tyrosine aminotransferase gene. The sequence comparison showed extensive homology over the entire region sequenced. In addition, DNA: DNA heteroduplex studies between the mouse and rat tyrosine aminotransferase genes revealed that this homology extends over the entire gene and its flanking sequences. The mouse tyrosine aminotransferase gene has been mapped distal to the serum esterase-1 locus on mouse chromosome 8, using a restriction fragment length polymorphism between two mouse species. Since the albino deletions are located on mouse chromosome 7, the assignment of the TAT gene to chromosome 8 suggests that a regulatory factor(s) affecting TAT gene expression acts in trans.

Animals↗

PubMed1983

Characterization of stimulatory activity for human pluripotent stem cells (CFUGEMM).

A medium conditioned by leukocytes in the presence of phytohemagglutinin (PHA-LCM) promotes the growth of human multilineage hemopoietic progenitors CFUGEMM which form mixed hemopoietic colonies in culture containing granulocytes, erythroblasts, megakaryocytes, macrophages and mononuclear cells with T-cell antigens. In addition PHA-LCM supports the growth of erythroid bursts (BFUE) and granulocytic colonies (CFUC). Stimulatory activities of PHA-LCM were characterized by gel filtration using Sephacryl S 300. The eluted growth promoting activities were rechromatographed on Sepharose 4 B covalently linked with Lentil Lectin. The stimulatory activities for noncommitted precursors CFUGEMM, and committed progenitors BFUE, and CFUC were detected in the unretained material i.e. the activities revealed no affinity to Lentil-Lectin. The apparent molecular weight of these stimulatory molecules ranged from 35,000-45,000, as determined by SDS gel electrophoresis (PAGE).

Bone Marrow Cells↗

PubMedDate not supplied

Correlation between the osmotic second virial coefficient and the solubility of proteins.

A correlation between the osmotic second virial coefficient and the solubility of proteins is derived from classical thermodynamics to support an empirical relation previously found by Wilson and co-workers (1). The model is based on the equality of fugacities of the protein in the equilibrium phases, with the details of the model depending on the standard state used. The parameters in this model have been fitted to data for several systems, mainly with lysozyme as the protein. The model is found to describe experimental data, with variations in protein concentration, salt type and concentration, temperature, and pH, both qualitatively and quantitatively. Agreement between the model and the experimental data is very good for protein solubilities up to 30 mg/mL. Above this value the model underpredicts the experimental data, probably as a result of multibody interactions that are not included in the model here. Variations of the model parameters with protein type, temperature, pH, and salt type are discussed.

Hydrogen-Ion Concentration↗

PubMedDate not supplied

Deduced amino acid sequence from the bovine oxytocin-neurophysin I precursor cDNA.

The nonapeptide hormone oxytocin-like arginine-vasopressin (AVP) is synthesized as part of a larger precursor polypeptide. The precursor also includes the neurophysin molecule with which the hormone is associated in the neurosecretory granules of the hypothalamo-pituitary tract. A protein of molecular weight (Mr) approximately 20,000 has been isolated from supraoptic nuclei of rat hypothalami which, after tryptic cleavage, released a neurophysin-like molecule of Mr approximately 10,000 and an oligopeptide related to oxytocin. This result was complemented by in vitro translation of bovine hypothalamic mRNA. Among the primary translation products a single polypeptide of Mr approximately 16,500 was shown to contain antigenic determinants recognized by specific antisera against bovine neurophysin I and oxytocin. Here we report the amino acid sequence of the bovine oxytocin-neurophysin I (OT-NpI) precursor which was derived from sequence analysis of the cloned cDNA. As is the case for the bovine arginine-vasopressin-neurophysin II (AVP-NpII) precursor, the signal sequence of the OT-NpI precursor is immediately followed by the nonapeptide hormone which is connected to neurophysin I by a Gly-Lys-Arg sequence. A striking feature of the nucleic acid sequence is the 197-nucleotide long perfect homology with the AVP-NpII precursor mRNA sequence encoding the conserved middle part of neurophysins I and II.

Amino Acid Sequence↗

PubMedDate not supplied

Recent gene conversion involving bovine vasopressin and oxytocin precursor genes suggested by nucleotide sequence.

The nonapeptide hormones arginine vasopressin (AVP) and oxytocin (OT) are synthesized in the hypothalamus together with their carrier proteins, the neurophysins, as common polypeptide precursors. The organization of these precursors has been established by sequence determination of cloned bovine cDNAs encoding prepro-arginine vasopressin-neurophysin II (prepro-AVP-NPII) and prepro-oxytocin-neurophysin I (prepro-OT-NPI). When the mRNA sequences coding for the conserved middle part of the neurophysins were compared, we found that these sequences are not merely similar but identical. The primary structure of the chromosomal genes now determined shows that both genes, which appear to have arisen by a gene duplication, are split into three exons, each encoding a functional domain of the precursor polypeptide. Sequence comparison reveals that the stretch of sequence identity within the two mRNAs is probably the result of a gene conversion encompassing exon B, which encodes the conserved part of the neurophysins, and part of the preceding intron.

Amino Acid Sequence↗

PubMedDate not supplied

Children of parapartum mentally ill mothers: a follow-up study.

A 2-year cohort of children (n = 75) of hospitalised first-episode parapartum mentally ill mothers in the mid-1970s in Stockholm were studied. The children were followed up during the school-age period from 1982 through 1992, and they were studied with regard to health development, academic achievement and family situation. Comparisons were made with matched controls. Data were collected from hospital case notes, the local tax authorities and school reports. No significant differences were found between the index children and the controls regarding the number of inpatient care episodes or days of inpatient care during the follow-up period. Nor was any significant difference found between the index and the control children regarding academic achievement as measured by the mean of all marks. Four index children and 2 controls were studying in schools for the mentally retarded. Seventy-four percent of the children of the patients were living with their mother, compared to 95% of the controls (p < 0.001). In conclusion, the children of mentally ill mothers in this longitudinal study did as well as the controls. The reason might be the social support provided by society (when needed) for these high-risk families in Sweden.

Adolescent↗