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Biomedical subjects

R C Williams

Publications and source records attributed to R C Williams.

At least 415 records · Page 23Linked to original sources
PubMed1978

Cyanobacterial phycobilisomes. Characterization of the phycobilisomes of Synechococcus sp. 6301.

A procedure is described for the preparation of stable phycobilisomes from the unicellular cyanobacterium Synechococcus sp. 6301 (also known as Anacystis nidulans). Excitation of the phycocyanin in these particles at 580 nm leads to maximum fluorescence emission, from allophycocyanin and allophycocyanin B, at 673 nm. Electron microscopy shows that the phycobilisomes are clusters of rods. The rods are made up of stacks of discs which exhibit the dimensions of short stacks made up primarily of phycocyanin (Eiserling, F. A., and Glazer, A. N. (1974) J. Ultrastruct. Res. 47, 16-25). Loss of the clusters, by dissociation into rods under suitable conditions, is associated with loss of energy transfer as shown by a shift in fluorescence emission maximum to 652 nm. Synechococcus sp. 6301 phycobilisomes were shown to contain five nonpigmented polypeptides in addition to the colored subunits (which carry the covalently bound tetrapyrrole prosthetic groups) of the phycobiliproteins. Evidence is presented to demonstrate that these colorless polypeptides are genuine components of the phycobilisome. The nonpigmented polypeptides represent approximately 12% of the protein of the phycobilisomes; phycocyanin, approximately 75%, and allophycocyanin, approximately 12%. Spectroscopic studies that phycocyanin is in the hexamer form, (alpha beta)6, in intact phycobilisomes, and that the circular dichroism and absorbance of this aggregate are little affected by incorporation into the phycobilisome structure.

Antigen-Antibody Reactions↗
PubMed1978

Reversible dissociation of the alpha beta dimer of tubulin from bovine brain.

The reversible, concentration-dependent dissociation of the alpha beta dimer of bovine brain tubulin (purified by phosphocellulose chromatography) has been demonstrated by equilibrium ultracentrifugation. The dissociation constant is approximately 8 X 10(-7) M at 4.6 degrees C in PM buffer (0.1 M piperazine-N, N'-bis(2-ethanesulfonic acid), 2 mM ethylene glycol bis (beta-aminoethyl ether)-N, N'-tetraacetic acid, 1 mM MgSO4, 0.1 MM guanosine triphosphate, 2mM dithioerythritol, at pH 6.9). This result was confirmed by observation of an appropriate dependence of the sedimentation coefficient of very dilute (is less than 0.5 mg/mL) tubulin on its concentration. Small zone gel filtration experiments on Bio-Gel P-150 also demonstrated an increase in peak elution volume with decreasing column load concentration. Reversibility of the dissociation was demonstrated directly by sedimentation velocity and gel filtration ion experiments on tubulin reconcentrated from dilute solution by pressure ultrafiltration. Control experiments accompanying the sedimentation equilibrium experiments showed that this tubulin retained, under the conditions of the experiments, both its ability to form microtubules and more than 70% of its initial colchicine-binding activity.

Animals↗
PubMed1978

Adherence of group A streptococci to pharyngeal cells: a role in the pathogenesis of rheumatic fever.

We used an assay in vitro to investigate the possible role of streptococcal adherence to human pharyngeal cells in the pathogenesis of acute rheumatic fever. There was no difference in adherence of rheumatic fever-associated and non-associated strains of group A streptococci to pooled pharyngeal cells of normal people. Likewise, streptococci not associated with rheumatic fever adhered equally well to cells taken from normal people and from patients with rheumatic heart disease. However, the pharyngeal cells of all nine rheumatic heart disease patients tested had increased avidity for adherence for a rheumatic fever-associated strain of streptococcus compared to the pharyngeal cells obtained from age- and sex-matched controls. Increased streptococcal adherence to pharyngeal cells of rheumatic fever-prone patients may play a role in the pathogenesis of rheumatic fever.

Adult↗
PubMed1978

Antibodies to synthetic polyribonucleotides in spouses of patients with inflammatory bowel disease.

Serum from patients with inflammatory bowel disease (I.B.D.) and their unaffected spouses bound significantly more synthetic single-stranded (poly.rA) and double-stranded (poly.rA.poly.rU) R.N.A. but not KB cell D.N.A. than did serum from age-matched controls and their spouses. Binding activity resided in Ig fractions and was predominantly of IgM class. A significant corelation was observed between the amount of double-stranded but not single-stranded R.N.A. bound by serum from patients and from their respective spouses. These findings provide indirect support for the presence of R.N.A. viruses in patients with I.B.D. and the transmission of such agents to their close personal contacts.

Antibodies, Viral↗
PubMed1978

Hemolytic-uremic syndrome after shigellosis. Relation to endotoxemia and circulating immune complexes.

To investigate three possible causes of the acute hemolysis in the hemolytic-uremic syndrome, we studied prospectively 207 children and 34 adults with shigellosis in Bangladesh. Nineteen children showed acute hemolytic anemia, a leukemoid reaction, thrombocytopenia and oliguria; nine other had, in addition, a serum urea nitrogen level of over 100 mg per diciliter. Eight of the nine had pseudomembranous colitis, and six of the nine died. The frequency of bacteremia was similar in all grades of shigellosis. Circulating immune complexes were found in 10 of 20 patients with uncomplicated shigellosis and in four of six with severe hemolytic-uremic syndrome. Limulus assay for endotoxemia was positive in nine of 18 patients with hemolysis (50 per cent) and three of 61 with uncomplicated shigellosis (5 per cent) (P less than 0.001). These data support the hypothesis that severe colitis in shigellosis is associated with circulating endotoxin from the colon producing coagulopathy, renal microangiopathy and hemolytic anemia.

Adolescent↗
PubMed1978

Clinical immunologic studies in systemic lupus erythematosus.

This review of recent and new directions in clinical immunologic studies of systemic lupus erythematosus (SLE) is restricted to the areas of lymphocyte surface markers, antigen binding lymphocytes, immune complexes, and lymphocyte hyporesponsiveness in lupus patients. First, it is not clear whether the T-lymphopenia observed in SLE is related to viral destruction of T cells, anti-lymphocyte antibodies, or tissue sequestration. Second, the increase in DNA-binding B lymphocytes observed in active lupus patients may be related to minor alterations in the balance of immunoregulatory T cells or to a bypass of DNA-specific helper T cells. Third, it is speculated that the removal of immune complexes which play a role in lupus glomerulitis by various extracorporeal immune absorbents may be important in the future therapy of SLE. Fourth, the mechanisms of T-lymphocyte hypofunction are unexplained. It is postulated from studies done in other diseases that this hypoactivity may be mediated by the secretion of prostaglandin or other humoral agents from one leukocyte subpopulation suppressing another potentially responsive lymphocyte subpopulation. Also an investigation into the lymphocyte subpopulation reactive with virus-infected fibroblasts may be useful in delineating immunoregulatory lymphocytes important in the pathogenesis of SLE.

Antigen-Antibody Complex↗
PubMed1978

Decrease in circulating immune complexes during hemodialysis.

Raji cell radioimmunoassay and Clq solid phase radioimmunoassay were used to determine serially circulating immune complexes in a patient with rapidly progressive glomerulonephritis who was receiving hemodialysis therapy. Initiation of hemodialysis was associated with a significant decrease in detectable immune complexes which, in turn, was associated with improvement and stabilization of renal function. We suggest that hemodialysis may remove immune complexes from the circulation and that it could be of therapeutic benefit in selected patients with presumed immune complex-mediated glomerulonephritis.

Adolescent↗
PubMed1978

Immunopathology of rheumatoid arthritis.

The central place of immunologic aberrations in the pathology of rheumatoid arthritis is now well established. It is the nature and interactions of these aberrations that still remain to be elucidated. Among the many puzzles being studied are the uniquely self-perpetuating nature of rheumatoid arthritis immune complexes and the role of complement and the prostaglandins in joint damage and pain.

Antigen-Antibody Complex↗
PubMed1978

Empiric analysis of the interactions involved in the formation of Fc receptor rosettes.

Erythrocytes coated with IgG were used in forming rosettes with lymphocytes and polymorphonuclear leukocytes to investigate Fc receptors. The density of the IgG-Fc coating on erythrocytes predictable influenced the number of rosettes formed with leukocytes. This relationship could be empirically described by application of the Hill equation derived from studies of molecular interactions in other biologic systems. The approximate Hill coefficient for Fc receptors was 2.4. These findings suggest at least two possible models for membrane Fc receptor function.

Binding Sites, Antibody↗