Search PubMed⌕ Search

Biomedical subjects

G Rhodes

Publications and source records attributed to G Rhodes.

At least 73 records · Page 4Linked to original sources
PubMed1986

Lack of reactivity of rheumatoid arthritis synovial membrane DNA with cloned Epstein Barr virus DNA probes.

Rheumatoid arthritis (RA) synovial membranes contain a 62,000 dalton (62 Kd) molecule that shares an antigenic epitope with the EBNA-1 antigen of Epstein Barr virus (EBV). This cross-reactive epitope(s) is defined by a monoclonal anti-EBNA-1 antibody (MoAb P135) and by a rabbit antibody directed against a (glycine-alanine)-containing synthetic peptide from the internal repeat region-3 (IR-3) of EBNA-1. To determine whether this 62 Kd protein may result from EBV infection of RA synovial membranes, we used cloned DNA probes from the Bam M, Bam V, and Eco D regions of EBV. These probes did not show detectable reactivity with RA synovial membrane DNA in Southern blotting or slot blotting experiments. Reconstruction experiments performed with purified EBV DNA demonstrated the ability to detect 0.03 pg of viral DNA per 20 micrograms of normal genomic DNA, or approximately 1 EBV copy per 100 cells. In contrast, we found a low but significant level of reactivity of RA synovial membrane DNA with the EBV-encoded Bam K probe that encodes the EBNA-1 antigen. However, this probe also was reactive with normal genomic DNA to a similar extent. These results suggest that the 62 Kd antigen in RA synovial lining cells is probably encoded by cellular genes similar to the IR-3 region of EBV and does not result from EBV infection of the RA synovial membrane.

Aged↗
PubMed1986

Rheumatoid arthritis synovial membrane contains a 62,000-molecular-weight protein that shares an antigenic epitope with the Epstein-Barr virus-encoded associated nuclear antigen.

A monoclonal antibody, selected for reactivity with the Epstein-Barr virus (EBV)-encoded antigen EBNA-1, exhibited strong reactivity with the synovial lining cells in joint biopsies from 10 of 12 patients with rheumatoid arthritis (RA) and adherent cells eluted from these tissues. No staining of RA synovial membrane frozen tissue sections or eluted synovial-lining cells was obtained with monoclonal antibodies directed against other EBV-encoded antigens (anti-p160, anti-gp200/350) or with monoclonal antibodies directed against antigens encoded by cytomegalovirus, herpes simplex viruses, or human T cell leukemia virus type I. Among 12 osteoarthritis and normal synovial biopsies only rare reactive cells were noted. Characterization of the antigen(s) in RA synovium by the Western immunoblotting technique revealed a 62,000-molecular-weight (mol-wt) protein, in contrast to the 70,000-85,000-mol-wt EBNA-1 antigen found in EBV-transformed cells. The structural basis for the cross-reactivity of the RA synovial membrane 62,000-mol-wt protein and the EBNA-1 antigen appears to reside in the glycine-alanine rich region of these molecules. A rabbit antibody directed against a synthetic peptide (IR3-VI-2) derived from the glycine-alanine-rich region of EBNA-1 reacted with the 70,000-85,000-mol-wt EBNA-1 antigen in EBV-infected cells and with the 62,000-mol-wt molecule in RA synovial membrane extracts. Since strong antibody responses to EBNA-1 are known to exist in RA patients, these results suggest that immune responses to a cross-reactive antigen may play a role in the pathogenesis of RA.

Animals↗
PubMed1985

Phytohemagglutinin binds to the 20-kDa molecule of the T3 complex.

Current findings have suggested that the T3 molecular complex is an essential antigenic signal transducer during T cell activation. Lectins, such as phytohemagglutinin (PHA), activate T cells nonspecifically. Conceivably, lectins may mediate their stimulatory action by affecting the T3 complex. In the present investigation we have studied the involvement of the T3 molecular complex in the PHA-mediated activation of T cells. We selectively modulated the surface expression of T3 molecules by anti-T3 antibody and subsequently tested the ability of the modulated cells to respond to PHA. Reduction of T3 expression by 70% resulted in 80% inhibition of the PHA response. This effect was specific for T3 since modulation of other T cell surface molecules (T4, T8) did not affect the PHA-induced mitogenesis. To determine if PHA could interact directly with the T3 complex, immunoblotting (Western blot) analyses of anti-T3 immunoprecipitates were performed. A 20-kDa member of the T3 complex reacted not only with the anti-T3 antibody, but also with PHA itself. These results provide the first evidence for direct binding of PHA to one of the molecules of the T3 complex. The combined data suggest that a major pathway of PHA-induced T cell activation involves the T3 complex. Possible activation mechanisms are discussed.

Antibodies, Monoclonal↗
PubMed1985

Perceptual asymmetries in face recognition.

Four experiments were carried out to investigate perceptual asymmetries in face recognition. Perceptual asymmetries favoring the half-face on the observer's left were found under free viewing conditions for both unfamiliar faces (Experiment 1) and famous faces (Experiment 3). For unfamiliar faces, this asymmetry was not obtained when fixation was controlled by presenting faces tachistoscopically (Experiment 2). For famous faces, the perceptual asymmetry favoring the half-face normally seen on the left did not appear to be retained in memory (Experiments 3 and 4). Asymmetries in face perception have been explained in terms of a direct access model of laterally effects. However, these results raise the possibility that asymmetric scanning or attentional factors may be important.

Attention↗
PubMed1985

Hickman catheter tip displacement.

In a series of 60 consecutive patients in whom Hickman catheters were placed for treatment of malignancy, four properly positioned catheter tips migrated secondarily from the superior vena cava to the ipsilateral jugular vein 2, 4, 21, and 25 days after placement. Three of the four patients had begun to have catheter dysfunction when the displacement was diagnosed. No satisfactory explanation for this rarely reported complication was evident in three of the cases. Maneuvers such as coughing, Valsalva's maneuver, and forceful heparin flushing produced no motion in three normally directed catheter tips in other patients observed under fluoroscopy. The phenomenon may be more common than previously reported. Evaluation of any new Hickman catheter dysfunction should include a chest x-ray film to ascertain the position of the catheter.

Adult↗
PubMed1985

Lateralized processes in face recognition.

In this paper a model is presented in which face recognition is analysed into several stages, each of which may be independently lateralized. Evidence is reviewed which suggests that lateralization is important at all stages of processing a face. Early visuospatial processing, and the creation and comparison of facial representations, appear to be carried out more efficiently by the right hemisphere. Comparisons based on discrete, namable features of faces may yield a left hemisphere advantage. It is also proposed that faces may activate semantic information, including names, more efficiently in the left hemisphere. The model is useful in resolving inconsistencies in the degree and direction of asymmetries found in face-recognition tasks. Suggestions are also made for future research.

Brain Damage, Chronic↗
PubMed1985

Human immune responses to synthetic peptides from the Epstein-Barr nuclear antigen.

Humans infected with Epstein-Barr virus (EBV), the causative agent of infectious mononucleosis, develop antibodies against a nuclear antigen (EBNA) that is present in virally transformed B lymphocytes. The EBNA protein contains a unique glycine-alanine repeating sequence. We have synthesized peptides corresponding to various regions of the EBNA molecule within and near this sequence. Rabbit antibodies against the peptides within the sequence reacted directly with the EBNA protein, as detected by Western blotting. The sera of individuals with antibodies against Epstein-Barr virus contained abundant antibodies also reactive with one or several of the synthetic peptides within the sequence. Moreover, human antibodies against these simple peptides were induced specifically early in the course of infectious mononucleosis. When compared with normal controls, antibody levels to the glycine-alanine peptides were significantly higher in patients with rheumatoid arthritis and progressive systemic sclerosis, but not in patients with two other autoimmune diseases. These results document that i) antibodies against the peptides detect the EBNA protein, ii) humans infected with EBV produce high titers of antibodies reactive with these synthetic antigens, and iii) antibody titers against the peptides are abnormally elevated in certain autoimmune diseases.

Amino Acid Sequence↗
PubMed1984

The immune response to Epstein-Barr nuclear antigen: conformational and structural features of antibody binding to synthetic peptides.

Naturally developing human antibodies to the Epstein-Barr nuclear antigen recognize synthetic peptides containing sequences from the unusual glycine-alanine region of this protein. We tested antibody binding to a series of peptides of from five to 20 amino acids in length. Peptides as small as seven amino acids could bind but optimal results required chain lengths of 15. Binding was extremely sensitive to small changes in the length and sequence of the peptide, and also to the temp of the reaction. The changes can be ascribed to two factors: (1) deletion of the site of antigen binding and (2) loss of peptide secondary structure.

Amino Acid Sequence↗
PubMed1983

Urinary profiles of volatile and acid metabolites in germfree and conventional rats.

Qualitative and quantitative differences in the urinary excretion of volatile and acidic metabolites in germfree and conventional rats were examined by capillary gas chromatography and gas chromatography/mass spectrometry. A number of carbonyl compounds, including several short-chain aliphatic ketones and acetophenone, were higher in the conventional urines, while many heterocyclic compounds (furan derivatives, benzothiazole and others) were lower. Both qualitative and quantitative differences were observed in the urinary excretion of acidic metabolites. Three meta-hydroxy phenolic acids appeared only in the conventional rat urines, while levels of many other aromatic and aliphatic acids were also higher.

Animals↗
PubMed1982

Quantitative alterations of steroid urinary profiles associated with diabetes mellitus.

Capillary gas chromatography was used for the acquisition of quantitative metabolic profiles of urinary steroids from normal subjects and diabetic patients. Structures of 70 steroid metabolites have been assigned tentatively through mass spectrometry. Quantitative differences between the groups of normal and pathological samples (both males and females) are seen primarily for androsterone, etiocholanolone, dehydroepiandrosterone, 11-oxygenated 17-ketosteroids, corticosteroid metabolites, and a newly discovered metabolite, recently identified as a C26 pentol. The only significant difference between two different age groups of normal males was shown by androsterone.

17-Ketosteroids↗
PubMed1982

Excretion of urinary volatile metabolites in response to alloxan induced diabetes of short duration in rats.

Alterations in urine volatile metabolites due to the induction of alloxan diabetes in the rat were examined by capillary gas chromatography and gas chromatography--mass spectrometry for the five days immediately following the onset of chronic hyperglycemia. Elevations of a number of metabolites were observed including several short chain ketones, acetophenone, 2-acetylfuran and indole. The value of urine volatile metabolic profiles as characteristic indicators of the diabetic condition is demonstrated through profiles obtained from a diabetic animal which spontaneously reverted to normal.

Animals↗
PubMed1982

Structural relationships between the endogenous volatile urinary metabolites of experimentally diabetic rats and certain neurotoxins (l).

High resolution glass capillary gas chromatography and GC/MS were utilized to examine qualitative and quantitative variations from normal of urinary volatile metabolites of long-term alloxan and streptozotocin diabetic rats. Volatile metabolites were structurally compared with known neurotoxins to examine any possible relationship between these metabolites and the development of the diabetic polyneuropathy.

Animals↗