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Biomedical subjects

M Ehrlich

Publications and source records attributed to M Ehrlich.

168 records · Page 10Linked to original sources
PubMedDate not supplied

A protein from human placental nuclei binds preferentially to 5-methylcytosine-rich DNA.

The methylation of vertebrate DNA at the 5-position of approximately 3-10% of its cytosine residues occurs in a sequence-specific and tissue-specific manner and has been implicated in the control of transcription. How these differences are established and how they mediate the initiation or maintenance of transcription are unknown. DNA methylation might also have other roles, such as modulating DNA replication, transposition, DNA repair or chromosome configuration. These other roles suggested for DNA methylation would be consistent with the finding that tissue-specific differences in methylation of certain gene regions, highly repeated satellite DNA sequences and whole genomes often do not correlate with transcriptional activity. For DNA methylation to modulate the expression, maintenance or duplication of chromosomes, there should be effector macromolecules, presumably proteins, which specifically recognize 5-methylcytosine (m5C) residues in DNA. We describe here the first identification of a mammalian protein that binds preferentially to m5C-rich DNA sequences.

Binding, Competitive↗
PubMedDate not supplied

Isolation of in vitro synthesized covalently closed circular double-stranded DNA by selective denaturation and filtration.

Based upon their resistance to irreversible denaturation, covalently closed circular (CCC) DNA (non-nicked, double-stranded circular molecules) can be purified by alkaline denaturation, neutralization, and filtration through a nitrocellulose membrane. This procedure offers a simple means of isolating in vitro synthesized CCC DNA molecules. The preparations of molecules obtained by this method consisted of 91-97% CCC DNA and contained no detectable inhibitors of biological activity or enzymatic digestion.

Bacteriophage phi X 174↗
PubMedDate not supplied

Transient synovitis: lack of serologic evidence for acute parvovirus B-19 or human herpesvirus-6 infection.

We evaluated children with transient synovitis for serologic evidence of infection with parvovirus B-19 (PVB-19) and human herpesvirus-6 (HHV-6) by using a prospective patient series in an urban children's hospital emergency department (ED). There were 20 children enrolled, aged 15 months to 6 years, diagnosed with transient synovitis. Clinical data were collected, and acute PVB-19 and HHV-6 immunoglobulin G (IgG) and IgM serologic titers were measured on all patients. Ten patients returned in 4-6 weeks for convalescent titers. The mean age was 4.1 years. Prodromal symptoms within a week of presentation were noted in 50% of patients, most commonly fever (25%) and upper respiratory infection (20%). Mean sedimentation rate was 11 mm/h (range, 2-22 mm/h), and mean peripheral white blood count was 11,000/microl (range, 6-21,000/ microl). No patient had increased acute or convalescent IgM titers for either PVB-19 or HHV-6, and no patient who returned for follow-up had an increase in serum IgG titers for either virus. A majority of patients (80%) had increased acute HHV-6 IgG titers, reflecting prior immunity to this virus. In conclusion, there is no evidence in this series that acute infection with PVB- 19 or HHV-6 causes or precedes transient synovitis.

Antibodies, Viral↗
PubMedDate not supplied

Analysis of methylation in the 5' region of the human alpha-galactosidase A gene containing a binding site for methylated DNA-binding protein/RFX1-4.

We examined methylation in the 5' untranslated region and surrounding sequences of the X-linked human alpha-galactosidase A gene. This region includes a methylation-dependent binding site for the MDBP/RFX1-4 transcription factor family. By bisulfite-based genomic sequencing, we determined the distribution of 5-methylcytosine residues from position +28 to +143 relative to the major transcription start site of the gene in almost 500 molecular clones from different tissues and individuals. The CpG methylation patterns in DNA from females differed from molecule to molecule with no indication of tissue-specificity or age-dependence. In contrast, the CG dinucleotides within this region were completely unmethylated in almost all of the DNA molecules cloned from male tissues. In female eutherian mammals, 50% of the molecules are expected to be methylated in an X-linked gene region in which methylation is coupled to gene silencing. Of the cloned DNA molecules from female tissues, 40% had 4 or more of the 9 CpG's methylated and the MDBP site was methylated in about one-fifth of the female tissue-derived DNA molecules.

Binding Sites↗