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Biomedical subjects

M P Roberts

Publications and source records attributed to M P Roberts.

At least 37 records · Page 2Linked to original sources
PubMed1989

Induction of transcription factor AP-1 by adenovirus E1A protein and cAMP.

Treatment of adenovirus-infected mouse S49 cells with cAMP analogs leads to the transcriptional induction of early viral genes. E1A proteins and cAMP work in synergy to activate several of these genes. We now demonstrate that the transcription factor AP-1 is modestly induced by cAMP in S49 cells and induced to significantly higher levels by cAMP in the presence of E1A proteins. Cytoplasmic levels of c-fos and junB mRNAs are rapidly increased by cAMP, and the induction is substantially stronger in the presence of E1A protein. The AP-1 activity binds efficiently to both AP-1 and activating transcription factor (ATF)/cAMP response element binding protein (CREB)-binding sites present in E1A-inducible promoters and presumably plays a role in the transcriptional activation of adenovirus genes by E1A proteins and cAMP.

Adenovirus Early Proteins↗
PubMed1988

Molecular diversity in the abdominal aortic aneurysm phenotype.

Abnormalities of collagenous peptides were detected among a group of 20 patients with abdominal aortic aneurysms, studied by high-performance liquid chromatography/NaDodSO4-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) analysis of the cyanogen bromide (CB) cleavage products of insoluble skin protein. Three abnormal patterns were identified as follows: (1) relative deficiency of a peptide with a relative molecular mass of approximately 58 kilodaltons (four patients); (2) relative decrease in the ratio of alpha-2 to alpha-1 (I) CB peptides (seven patients); and (3) decreased detection of all collagenous CB and pepsin cleavage products (one patient, who was also heterozygous for the Z allele of alpha 1-antitrypsin). The "minimal hypothesis" to explain these findings is that most of the observed abnormalities can be explained by collagenolysis in vitro, although a mutation in the primary structure of collagen has not been ruled out in all patients. Molecular heterogeneity appears to occur within the aneurysm phenotype, and the findings in the patient in group 3 allow identification of one possible risk factor in abdominal aortic aneurysmal disease that has a genomic assignment.

Amino Acids↗
PubMed1986

Cell proliferation and expression of the transferrin receptor gene: promoter sequence homologies and protein interactions.

A 365-bp fragment from the 5' region of the human transferrin receptor gene has been subcloned and sequenced. This fragment contains 115 bp of flanking sequence, the first exon, and a portion of the first intron. It contains a TATA box, several GC-rich regions, and is able to efficiently promote expression of the bacterial CAT gene in mouse 3T3 cells. Sequence comparisons demonstrate that this DNA segment has homology to the promoter regions of the human dihydrofolate reductase gene and the mouse interleukin 3 gene, as well as to a monkey DNA sequence that has homology to the SV40 origin and promotes expression of an unidentified gene product. Several high molecular mass proteins that interact with the transferrin receptor gene promoter have been identified. The activity of these proteins is transiently increased in 3T3 cells that have been stimulated by serum addition. This increase precedes a rise in transferrin receptor mRNA levels in the cytoplasm, which in turn precedes entry of the cells into S phase. DNase I footprinting of the transferrin receptor promoter reveals several protein binding sites. Two of the sites are within the conserved GC-rich region of the promoter. One of these binding sites probably interacts with Spl, while the second interacts with an uncharacterized protein.

Binding Sites↗
PubMed1985

Use of a protein-blotting procedure and a specific DNA probe to identify nuclear proteins that recognize the promoter region of the transferrin receptor gene.

We describe a procedure for detecting high-affinity, sequence-specific DNA-binding proteins from crude nuclear extracts. The technique utilizes electrophoretic transfer of NaDodSO4/PAGE-fractionated proteins onto nitrocellulose filters. Incubation of the filters with a 5% (wt/vol) solution of nonfat dry milk effectively blocks nonspecific and low-affinity DNA-binding sites. Incubation of the blocked filters with radiolabeled DNA under optimal binding conditions and subsequent autoradiography reveals high-affinity DNA-protein interactions. We have used this procedure to identify proteins that bind specifically to the promoter region of the transferrin receptor gene.

Base Sequence↗
PubMed1984

Cerebellopontine angle gumma.

A rare lesion, a gumma in the cerebellopontine angle, is reported. Gumma may mimic other more commonly occurring cerebellopontine angle tumors. The computed tomographic (CT) appearance and histological characteristics are discussed. The literature of cerebral gumma is reviewed. This is the only reported case of cerebellopontine angle gumma seen on CT scan and verified histologically at operation.

Cerebellar Diseases↗
PubMed1983

A sequence related to 4.5 S RNA and the B1 family of repeated DNA in the 5' flanking region of the mouse beta-globin gene.

A beta-globin gene probe containing 5' flanking DNA hybridizes to a small nuclear RNA from Friend erythroleukemia cells, which was subsequently identified as 4.5 S RNA. This hybridization is shown to reflect complementarity between the Alu consensus region of 4.5 S RNA and the DNA sequence between nucleotides -33 and -48 from the beta-globin gene transcription initiation site.

Animals↗
PubMed1983

Femoral neuropathy and retroperitoneal hemorrhage.

A case of femoral neuropathy secondary to psoas muscle hematoma in a patient on warfarin sodium anticoagulation therapy is presented. Computed tomography was used to establish the diagnosis. The literature is reviewed with regard to the pathophysiology, clinical presentation, and therapy of this case. Surgical decompression is suggested to shorten the recovery period and minimize residual neurological deficit.

Femoral Nerve↗
PubMed1982

Ribosomal RNA sequence conservation and gene number in the larval brine shrimp.

The haploid genome size of Artemia is determined to be about 0.9 X 10(12), as evidenced both by Feulgen microspectrophotometry of individual diploid class nuclei, which are but one of five polyploid classes present within the larvae, and by analysis of the reassociation kinetics of the isolated single copy DNA component. Polysomes isolated from 24-h incubation stage larvae contain an average of 10 ribosomes per messenger RNA molecule. Their rRNAs are found to have sedimentation coefficients of 18 S and 26 S, corresponding to molecular weights of 0.70 X 10(6) and 1.40 X 10(6), respectively, as determined by polyacrylamide electrophoresis and also by sucrose density centrifugation. Denaturation in glyoxal followed by agarose gel electrophoresis shows that unlike deuterostome rRNAs, Artemia 26 S rRNA contains a cryptic nick about midway in the molecule, which is not found in the 18 S molecule. Isolated rRNAs were labelled in vitro with 125I and hybridized with filter-immobilized DNA to saturation, which occurred at 0.051% for Xenopus, and at 0.074% for Artemia. From these results, it is calculated that in the haploid Artemia genome there are about 320 copies of the (18 S + 26 S) ribosomal RNA genes. Reciprocal heterologous hybridizations between these two species show that they share about 30% homology between their rDNA coding sequences.

Animals↗
PubMed1982

Theory into hospital practice: a pilot implementation.

Implementing the Adaptation Model required that the model's concepts be explicitly identified, defined, and understood. Guidelines, standards and tools had to be revised or developed. Effective nursing administration leadership and the personal and professional commitment of administrators, educators, and staff nurses to the goal were necessary ingredients. The abstract nature of theory often requires sheer determination and hard thinking if it is to be effectively applied to practice. A formal education process must also be dynamic and ongoing. Project members continue to gain greater insight into the model's structure, identify problems in its application, and seek ways to solve them. Their combined, concentrated efforts have proved a cost-effective way to close gap between education and practice. The project's initial outcomes, increased patient satisfaction and expanded professional nursing, support the application of the Adaptation Model in our hospital. Further validation of its structure and the value of its outcomes, however, needs additional study, and extended application in multiple practice settings. Validation of the Roy Adaptation Model or any of the evolving conceptual frameworks for nursing practice requires use, input, and evaluation by nurses in all settings. Opening the theoretical domain to hospital nurses needs the support and leadership of nursing and hospital administrators.

Adaptation, Psychological↗
PubMed1982

Thrombosed vein of Galen aneurysm.

The authors report a case of thrombosed vein of Galen aneurysm in a 4.5-year-old girl with craniofacial dysostosis (Crouzon's disease). Six previously reported cases appear in the literature. The initial presentation is often associated with the symptoms and signs of hydrocephalus. Computed tomography shows an enhancing mass in the region of the posterior 3rd ventricle with the characteristic "target sign." Arteriography of all aspects of both the anterior and the posterior cerebral circulation is essential. Surgical results in cases of vein of Galen aneurysm have generally been poor, but recent reports of successful operative intervention to treat the thrombosed variety promise satisfactory treatment.

Calcinosis↗
PubMed1976

The iron and subunit binding sites of hemerythrin. The role of histidine, tyrosine and tryptophan.

Of the three tyrosine residues available for nitration by tetranitromethane in hemerythrin, nitration of tyrosine residue 70 has no effect on dissociation of octomers to monomers, but nitration of tyrosines 18 and/or 67 results in dissociation to monomers. The latter data suggests these residues are important for subunit association. The reactive sulfhydryl, the modification of which produces dissociation, was protected as a mixed disulfide during the nitration but was regenerated for analysis of the state of association. Residue 70 can be selectively modified because of its exposed position and perhaps because of its slightly lower pk of 6.9, compared to 7.3 as an average of all nitrotyrosines in a completely nitrated hemerythrin. Solvent perturbation studies in 20% Me2SO indicate that 3 tyrosines, in agreement with the nitration results, and 2 tryptophan residues are exposed; however, oxidation at a 2-fold molar excess of N-bromosuccinimide oxidizes three tryptophan whereas a 3.5-fold excess oxidizes all four, but results in a rapid active site destruction. Photo-oxidation with methylene blue results in oxidation of only two tryptophan residues. These data have been interpreted to indicate that two tryptophans are free and two are involved in subunit association. Photo-oxidation with methylene blue results in the destruction of three histidines but no decrease in active site absorption. Histidine modification with diethyloxydiformate shows that three histidines react with no change in active site absorption. These results indicate that four histidines are unreactive toward these modifying agents and are therefore either buried or are ligands to the iron.

Binding Sites↗