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Biomedical subjects

C E Roberts

Publications and source records attributed to C E Roberts.

16 recordsLinked to original sources
PubMed1997

Molecular characterization of the B-box protein-protein interaction motif of the ETS-domain transcription factor Elk-1.

The ternary complex factor (TCF) subfamily of ETS-domain transcription factors form ternary complexes with the serum response factor (SRF) and the c-fos SRE. Extracellular signals are relayed via MAP kinase signal transduction pathways through the TCF component of the ternary complex. Protein-protein interactions between TCFs and SRF play an essential role in formation of this ternary complex. A 30 amino acid sequence encompassing the TCF B-box is sufficient to mediate interactions with SRF. In this study we have identified amino acids which are critical for this interaction and derived a molecular model of the SRF binding interface. Alanine scanning of the Elk-1 B-box reveals five predominantly hydrophobic residues which are essential for binding to SRF and for ternary complex formation in vitro and in vivo. These amino acids are predicted to lie on one face of an alpha-helix. Peptides encompassing the B-box retain biological activity and have helix-forming propensity. alpha-Helix and ternary complex formation is disrupted by the introduction of helix-breaking proline residues. Our results are consistent with a model in which the Elk-1 B-box forms an inducible alpha-helix which presents a hydrophobic face for interaction with SRF. We discuss the wider applicability of our results to similar short protein-protein interaction motifs found in other transcription factors.

3T3 Cells↗
PubMed1994

Data: which states have it?

Data is king. Data is power. Data is the path to quality. Quality is what our patients want and deserve. Do you use your hospital data to its fullest potential? Do you compare your data to others? Are you improving? If not, you need to investigate ways to fully utilize your data.

Databases, Factual↗
PubMed1992

Characterization of a series of novel fucose-containing glycosphingolipid immunogens from eggs of Schistosoma mansoni.

Lipid extracts of eggs, worms, and cercariae of the parasitic trematode Schistosoma mansoni have been shown to contain a large number of highly immunogenic glycolipids (Weiss, J. B., Magnani, J. L., and Strand, M. (1986) J. Immunol. 136, 4275-4282). Three fractions of schistosome egg glycolipids were selected on the basis of their reactivity with an anti-schistosome monoclonal antibody (128C3/3), which recognizes a developmentally regulated carbohydrate epitope present on both glycolipid and glycoprotein antigens from S. mansoni. These fractions were purified by silica gel chromatography and preparative high performance thin layer chromatography and characterized by monosaccharide, fatty acid, and linkage analysis with gas chromatography-mass spectrometry, as well as by positive and negative ion fast atom bombardment-mass spectrometry. The immunogens were shown to be glycosphingolipids having homologous structures based on a highly novel extension of glucosylceramide. Monosaccharide inhibition studies indicated that the epitope recognized by 128C3/3 residues in an outer region of the immunogens consisting of Fuc2GlcNAc (where Fuc is fucose) repeating units. The largest antigen characterized may have the following structure, based on the evidence presented in this paper. [sequence: see text] The evidence indicated the existence of a series of glycan structures created by deletions of one or more Fuc1----3 side chains from the above structure.

Animals↗
PubMed1992

Extended type-1 chain glycosphingolipid antigens. Isolation and characterization of trifucosyl-Leb antigen (III4V4VI2Fuc3Lc6).

A Lewis-b-active glycosphingolipid containing a repetitive type-1 chain carbohydrate core was isolated from human colonic adenocarcinoma cell line Colo205. This glycosphingolipid was purified by HPLC and preparative high-performance thin-layer chromatography and its structure elucidated by positive-ion fast-atom-bombardment mass spectrometry with collision-induced disassociation, 1H-NMR spectroscopy and methylation analysis. The glycosphingolipid was found to be a trifucosylated derivative of this novel carbohydrate core, having the following structure: [formula; see text].

Adenocarcinoma↗
PubMed1992

Sonographic demonstration of air in the myometrium. A complication of culdocentesis.

Six cases are presented in which air was seen in the myometrium in the distribution of the arcuate vessels during sonography performed after culdocentesis to exclude ectopic pregnancy. Three of these patients had viable intrauterine pregnancies; the others had an incomplete abortion, a complete abortion, and a right ectopic pregnancy. This relatively rare complication of culdocentesis should be kept in mind, especially when scanning patients with suspected inflammatory process of the uterus, so as not to confuse air in the arcuate vessels with a uterine abscess.

Abortion, Incomplete↗
PubMed1991

Extended type 1 chain glycosphingolipids: dimeric Lea (III4V4Fuc2Lc6) as human tumor-associated antigen.

Glycolipid extracts from various human cancer tissues and cell lines showed the presence of a slow-migrating glycolipid component which was strongly reactive with monoclonal antibody (mAb) NCC-ST-421 (raised against human gastric adenocarcinoma) and weakly cross-reactive with anti-Lea mAbs. The slow-migrating glycolipid was isolated from human colonic adenocarcinoma cell line Colo205 grown in nude mice, and was purified by high-performance liquid chromatography followed by preparative thin-layer chromatography. Its structure was elucidated by sequential enzymatic degradation and thin-layer chromatography immunostaining of the degradation products with various mAbs, 1H NMR spectroscopy, positive-ion fast atom bombardment mass spectrometry, and methylation analysis. The major slow-migrating component reacting with mAb ST-421 was identified as dimeric Lea, with the structure as follows. [formula: see text] Antigens containing this structure and various analogous structures (including enzymatically synthesized Lea/Lex hybrid antigen) were tested with ST-421. While the mAb was equally reactive with dimeric Lea and Lea/Lex, only the former was chemically detectable as the slow-migrating glycolipid from the tumor extract. ST-421 showed less reactivity with simple Lea (III4FucLc4) or extended Lea (V4FucLc6, and/or IV3Gal beta 1----3[Fuc alpha 1----4]GlcNAcnLc4), and was not reactive with Lex/Lex (dimeric Lex). It was concluded, therefore, that the major tumor-associated slow-migrating glycolipid reacting with ST-421 has the dimeric Lea structure shown above. Since extension of lacto-series structure has been shown to be limited to type 2 chain in normal cells and tissues, extended elongation of type 1 chain as shown in this structure represents a novel tumor-associated epitope.

Adenocarcinoma↗
PubMed1991

Use of the Natural Death Act in pediatric patients.

OBJECTIVE: To review the use of Natural Death Act declarations (living will procedures) in pediatric patients. The implementation of such declarations for children is now possible in six states, including Texas, by specific statutory provisions. DESIGN: Retrospective study. SETTING: Pediatric ICU in a university hospital. PATIENTS: Records of patients who had a Texas Natural Death Act declaration, either discussed and signed or discussed only, were studied. Patients who had another vehicle of limiting care (e.g., a do-not-resuscitate order) were excluded from the study. MEASUREMENTS AND MAIN RESULTS: Reviewed characteristics included age, primary diagnosis, and concurrent complications. Also examined were who raised the issue of limiting care (parent or physician), the initial reaction of the other party, what support was withdrawn, what support was added, the final outcome (including the time from implementing limited care to death), and the description of witnesses. Discussions were held with parents of 17 patients, and 13 Natural Death Act declarations were actually implemented. In all but three instances, the patient died within 4 hrs from the time support was withdrawn. The main supports that were withdrawn were ventilators and catecholamines. In half of the cases, morphine sulfate was added for anticipated pain relief and sedation. All decisions were reached by close consultation between the family and the physicians, with the physicians raising the issue in 11 of the 17 cases and the family raising the issue in six cases. In 15 of the 17 patients, consultation with the Bioethics Committee was not necessary. The majority of difficulties involved resolving issues that beset patients with HIV infections, and finding appropriate witnesses as prescribed by the statute. CONCLUSIONS: We conclude that the Natural Death Act works well in situations involving dying children and their parents.

Adolescent↗
PubMed1990

The patency of the retinal vasculature to erythrocytes in retinal vascular disease.

This paper presents the first evidence that in retinas with experimentally induced vascular disease some vessels contain only plasma. This was demonstrated by a histologic technique developed specifically to test the hypothesis that at some stage in retinal vascular disease, vessel patency to erythrocytes is lost before vessels close to plasma. Using this technique, we visualized three major components of the circulation at all retinal locations: the erythrocytes; the plasma as marked by the presence of 0.2-micron fluorescent microspheres; and all functioning endothelial cell nuclei, which were marked by the fluorochrome bis-Benzimide. It was assumed that the distributions of the erythrocytes and small particles in retinal whole mounts reflected accurately the true in vivo distributions at the moment of circulation arrest. Postenucleation the retina can be viewed and photographed within 45 min of circulation arrest. The technique was used on normal rats and on rats induced with a fast-developing model of retinal vasculopathy. With this model, we demonstrated retinal vascular segments perfused by plasma but containing no erythrocytes with functioning endothelial cells in the vessel walls. This may mean that an early factor in some retinal vascular pathologies is tissue hypoxia caused by reduced erythrocyte perfusion.

Alloxan↗
PubMed1990

Strategies for characterization of ganglioside inner esters. I--Fast atom bombardment mass spectrometry.

A comparison of old and new fast atom bombardment (FAB) mass spectrometric strategies for characterization of ganglioside inner esters (lactones) is presented. Data obtained for lactones of GD3 (NeuAc alpha 2----8NeuAc alpha 2----3Gal beta 1----4Glc beta 1----1Cer) using negative ion FAB mass spectrometry of underivatized materials, negative ion FAB mass spectrometry following ammonolysis, and positive ion FAB mass spectrometry following ammonolysis and permethylation are presented and discussed. The latter method uses well-known reactions to produce a novel type of ganglioside derivative, highly amenable to analysis by positive ion FAB mass spectrometry, which is introduced to simplify unambiguous location of NeuAc residues involved in ester linkages to other sugars.

Gangliosides↗
PubMed1989

A novel strategy for unambiguous determination of inner esterification sites of ganglioside lactones.

A method is described which is suitable for protection of all free hydroxyl groups of a glycosphingolipid under conditions which will not cleave ester linkages, including inner ester linkages characteristic of ganglioside lactones. The protecting methoxyethoxymethyl group is stable in alkaline media, surviving permethylation procedures which introduce a methyl ether at all sites previously acylated. Hydrolysis, reduction, and acetylation then yield alditol acetate derivatives which can be analyzed by conventional GC-MS to locate the methyl ether groups. The method is used to locate the inner esterification site of GM3 lactone.

Acetates↗
PubMed1978

Nutritional management of the adult patient undergoing peritoneal dialysis.

Until the last few years, maintenance peritoneal dialysis (PD) often was associated with progressive wasting due to frequent episodes of peritonitis, loss of considerable amounts of protein into the dialysate, and poor nutritional intake. Recently, available techniques have made PD a feasible alternative for the long-term care of the patient with end-stage renal failure. The incidence of peritonitis has been markedly reduced, and protein loss is only 4 to 20 gm. per dialysis treatment. Preliminary studies have shown no differences in the nutritional status of patients undergoing PD or hemodialysis, although both groups have evidenced malnutrition. In the patient undergoing PD, daily intakes of 1.2 to 1.5 gm. protein and 35 kcal per kilogram body weight are recommended. During times of stress, parenteral administration of nutrients may be necessary. Dietary supplements may often be required chronically. Careful studies are needed to difine the nutritional needs of the patient undergoing PD.

Dietary Carbohydrates↗