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Biomedical subjects

G Virella

Publications and source records attributed to G Virella.

At least 127 records · Page 7Linked to original sources
PubMed1981

Plasma factors and platelet aggregation in diabetes mellitus.

Plasma fron some diabetic patients, particularly those with advanced retinopathy and nephropathy, will potentiate ADP-induced platelet aggregation. Partial purification of plasma from a diabetic patient with nephropathy has yielded a fraction with this activity. A linea dose response curve relating plasma factor (6.25-50 ng protein) and platelet aggregation or ATP release at 4 minutes after adding ADP has been found. The effect is blocked by exposure of platelets to aspirin, prostaglandin or eicosapentaenoic acid. Soluble immune complexes are found in many diabetics and are known to be platelet-active. We have isolated immune complexes from sera of six diabetics and have shown enhancement of the second phase of platelet aggregation and of ATP release by these immune complexes from platelets sensitized to ADP. We conclude that plasma proteins from diabetics may accentuate ADP-induced platelet aggregation and ATP release, possibly by acting through prostaglandin pathways. Immune complexes appear to be one group of plasma proteins with such platelet active behavior. Further studies are indicated to characterize these plasma factors and to assess their in vivo significance regarding platelet function and vascular disease in diabetes mellitus.

Antigen-Antibody Complex↗
PubMed1980

Purification of cytoplasmic antigens from the mycelial phase of Candida albicans: possible advantages of its use in Candida serology.

The serology of candidiasis is complicated by the use of poorly defined antigens. Total extracts of the yeast phase have been commonly used as "cytoplasmic' antigen, without regard to the significant amounts of carbohydrate that may contaminate such preparations. This is particularly true in the case of commercially available antigens that have been used as cytoplasmic antigens but actually are richer in carbohydrate than in protein. Affinity chromatography in concanavalin A - Sepharose provides a simple procedure to separate carbohydrates, mainly mannan, from protein antigens in whole Candida extracts. By using mannan-poor antigens, the specificity of serological reactions can be increased considerably, since both the positive reactions seen in a-symptomatic donors and the cross-reactions seen in patients infected with other fungi are due to anti-mannan antibodies. In contrast, both anti-mannan and anti-cytoplasmic antigen antibodies can be detected in patients suspected of systemic candidiasis. On the other hand, absolute specificity may never be achieved for systemic candidiasis. We have found antibodies against cytoplasmic antigen in a patient allergic to C. albicans, in whom the microorganism was isolated from fecal material. It appears that, under favorable conditions, mucosal sensitization may also trigger as systemic reaction directed against both mannan and cytoplasmic antigens.

Antigens, Fungal↗
PubMed1980

A quantitative immunofluorescence test for the detection of anti-Candida antibodies.

A quantitative immunofluorescence assay for anti-Candida antibodies has been developed using a recently introduced system that includes an automatic fluorometer and a special immunoadsorbent for antigen coating. A commercially available cytoplasmic antigen preparation was adsorbed into the substrate, and after incubation with sera from patients with systemic candidiasis or from normal controls, the antibodies bound to the antigen-coated immunoadsorbent were revealed by the use of fluorescein-labeled antisera to human immunoglobulins. Using doubling dilutions of a high titer serum, a positive relation was found between antibody concentration and the logarithm of the intensity of fluorescence. Quantitative assays of unknown samples were performed using a calibration curve constructed from dilutions of that strongly positive sample; the results of antibody determinations were expressed as percentages of the control. Seven of 9 sera from patients with systemic candidiasis, and only 2 of 42 from asymptomatic individuals, had antibody levels considered significant in this assay. Precipitating antibodies were detected by counterimmunoelectrophoresis in all patients and in 18 of the asymptomatic controls; measurable antibody levels were also found in 14 controls showing no precipitating antibodies. This assay is simple, sensitive and inexpensive, and its quantitative nature makes it useful in the investigation of the immune response to C. albicans.

Antibodies, Fungal↗
PubMed1980

Paraprotein-induced hyperviscosity. A reversible cause of stroke.

Although the occurrence of the hyperviscosity syndrome with IgG plasma cell leukemia is unusual, it should be considered in the evaluation of patients with focal neurologic deficit with or without a known malignant paraproteinemia. If serum viscosity is elevated, then emergent plasmapheresis should be considered, as it may reverse the neurologic deficit.

Blood Viscosity↗
PubMed1980

Immunoglobulin quantitation and enumeration of immunoglobulin-producing cells: comparison of two index of B-cell activation.

Human lymphocytes were cultured under different conditions to determine the effects of technical variations on the response to pokeweed mitogen (PWM) and Staphylococcus aureus as measured by (a) quantitation of immunoglobulins (Ig) in the culture supernatants and (b) enumeration of Ig-secreting cells (ISC) by a reverse plaque technique. The highest numbers of ISC were measured when the cells were cultivated in standing tubes, without glutamine supplementation during the culture, and at a concentration of 1 x 10(6) cells/ml. The highest Ig concentrations were measured under similar conditions, except that somewhat higher values were obtained with cell cultivated at 1 x 10(6)/ml in 2 ml cultures with PWM stimulation and 2.5 x 10(6)/ml in 1 ml cultures with S. aureus stimulation. In time-course studies, peak ISC responses occurred on day 5 with each mitogen, whereas extracellular Ig levels kept rising until day 7, possibly owing to accumulation of secreted Ig. Measurements of the numbers of ISC and of secreted Ig levels in simultaneous cultures of lymphocytes from the same donors showed no correlation; however, co-stimulation of cultures with PWM and concanavalin A (to stimulate suppressor cells) depressed both Ig levels and ISC numbers. These results suggest heterogeneity in the plaque-forming cell population with respect to rate of Ig secretion, but indicate that these two techniques both reflect B-cell activation. They should not, however, be considered interchangeable, and the two probably should be used in conjunction for complete characterization of B-cell activation.

Antibody-Producing Cells↗
PubMed1980

Induction and suppression of immunoglobulin synthesis in cultures of human lymphocytes: effects of pokeweed mitogen and Staphylococcus aureus Cowan I.

The synthesis and secretion of immunoglobulins by human peripheral blood mononuclear cells in cultures stimulated with pokeweed mitogen or Staphylococcus aureus Cowan I were evaluated by enumeration of cells containing cytoplasmic immunoglobulins and cells actively secreting immunoglobulins, and by quantitation of immunoglobulins released into culture supernatants. The two mitogens caused comparable stimulation of immunoglobulin production; however, in contrast to pokeweed mitogen, S. aureus was active in cultures depleted of T lymphocytes, and its stimulatory effects were resistant to the influence of suppressor T cells generated by co-stimulation with concanavalin A or by preincubation without mitogenic stimulus. These results indicate distinct pathways of induction and suppression of immunoglobulin synthesis for these two polyclonal B cell activators, and suggest that stimulation by S. aureus is less thymus dependent than that induced by pokeweed mitogen.

Aging↗
PubMed1980

Immunonephelometric assay of human apolipoprotein AI.

We report an immunonephelometric assay for apolipoprotein AI, which involves use of a laser nephelometer and an antiserum prepared in our laboratory. Coefficients of variation were 2.5% within-run, 6.3% between-run. Several types of manipulation of the samples (heating, delipidation, dissociation with urea), reportedly necessary for accurate determinations by radioimmunoassay or gel diffusion immunoassay, did not substantially affect results obtained with our technique. The assay is sensitive, reproducible, and simple, and appears suitable for routine use.

Apolipoprotein A-I↗
PubMed1980

Experimental model of chronic serum sickness. Relationships between proteinuria, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and glomerular and extraglomerular renal pathology.

The evolution of proteinuria in rabbits with experimentally induced chronic serum sickness was followed up longitudinally by analytical and quantitative assays. The results suggest that sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is a more sensitive index of kidney malfunction than are total-protein assays or the quantitation of albumin and lysozyme. In some rabbits that showed abnormal proteinuria by SDS-PAGE, no histologic evidence of pathologic damage or of deposition of immune complexes in the kidneys was found. This suggests that SDS-PAGE may detect functional alterations at early stages of kidney damage when the lesions are either undetectable or reversible. In one rabbit that was killed after normalization of the proteinuria, immunofluorescence tests indicated deposition of C3, IgG, and fibrinogen, but there was no histologic evidence of kidney damage.

Animals↗
PubMed1980

Simplified method for detecting anti-insulin antibodies and insulin-anti-insulin immune complexes.

A simplified approach for estimating free and total anti-insulin antibodies and soluble insulin-anti-insulin immune complexes in serum has been developed and evaluated. For determination of free anti-insulin antibodies, a binding ratio for 125I-labeled insulin at fivefold serum dilution is calculated; the binding ratios obtained are reproducible (run-to-run coefficient of variation, 7.3%) and correlate well with titration of anti-insulin antibodies by other techniques (correlation coefficient, 0.9327). Total anti-insulin antibody concentrations are determined by calculating the [125I]insulin binding ratio for a sample previously acidified, adsorbed with acid dextran-coated charcoal, and neutralized. The difference in binding ratios between two aliquots of the same serum, one diluted 10-fold without manipulation and the second studied at an identical dilution after acidification and removal of free insulin, is taken as an index of the presence of soluble insulin-anti-insulin immune complexes. Because the tests can be performed at a single dilution, both time and materials are conserved without apparent loss of discrimination between sera with high antibody titers and high concentrations of insulin-anti-insulin immune complexes and sera with negative titers or low concentrations.

Antigen-Antibody Complex↗
PubMed1980

Measurements of extracellular immunoglobulins as an index of B cell function.

We have developed a method for measuring the activation or suppression of B cells in culture by determination of immunoglobulins released into the extracellular fluid, using a conventional, nonisotopic assay. To avoid the interference of human serum proteins in the assays, cultures were established in medium supplemented with fetal calf serum. This caused some B cell activation, as reflected by the release of small amounts of immunoglobulins (1.5 to 0.7 microgram/ml IgG, 0.8 to 1.4 microgram/ml IgA, 0.6 to 0.7 microgram/ml IgM on day 7), but pokeweed mitogen stimulation resulted in the release of substantially larger amounts of immunoglobulins (8.2 to 4.6 microgram/ml IgG, 3.8 to 2.9 microgram/ml IgA, 8.0 to 4.0 microgram/ml IgM on day 7). Stimulation with Staphylococcus aureus (Cowan I) also resulted in release of immunoglobulins, with somewhat higher levels of IgM, and the release was inhibited by a suppressive substance obtained from Streptococcus intermedius. Time-course curves for immunoglobulin production by cultures stimulated with pokeweed mitogen and S. aureus showed interesting individual variations, but in general the levels began to rise consistently by day 4 or 5 and maximum levels were reached by day 7. These studies show that determination of extracellular immunoglobulins can be used as an index of B cells activation in routine studies.

B-Lymphocytes↗
PubMed1979

Urinary high density lipoprotein in minimal change glomerular disease and chronic glomerulopathies.

Serum lipids and lipoproteins and urinary apolipoprotein A (Apo A) were determined in two groups of patients. One group consisted of 11 children (ages ranging from 4 to 14 years) with minimal change glomerular disease. The other group consisted of 13 patients, eight less than 19 years old five adults, with different types of chronic glomerulopathy. Elimination of urinary lysozyme was a feature of chronic glomerulopathies, and creatinine clearances were also significantly lower in this group. Patients with chronic glomerulopathies had significantly lower HDL cholesterol and Apo A concentrations in their sera. In contrast, urinary Apo A concentrations were significantly higher in patients with chronic glomerulopathies, who also showed significantly lower urinary protein selectivities. Lipoprotein electrophoresis of urines containing Apo A showed distinct high-density lipoprotein (HDL) fractions, suggesting that HDL is eliminated in the urine as a result of increased glomerular permeability. This is also supported by a correlation coefficient of 0.77 between the selectivity indices and the ratio of urinary Apo A to total proteinuria. The determination of urinary Apo A appears to give valuable diagnostic information in patients with glomerular disease. According to our results the absence of urinary Apo A is very suggestive of minimal change glomerular disease.

Adolescent↗
PubMed1979

Association between immunoglobulin allotypes and immune responses to Haemophilus influenzae and Meningococcus polysaccharides.

Serum samples were collected from 20 healthy White and 33 Black infants before and after immunisation with three doses of diphtheria-pertussis-tetanus vaccine and with one dose of Haemophilus influenzae type b polyribose phosphate vaccine and meningococcal group A and group C polysaccharide vaccines. Antibodies to these immunogens were measured and sera were allotyped for several Gm, A2m, and Km antigens. A highly significant association was found between the Km(1) allotype and the immune responses (difference between post-immunisation and pre-immunisation antibody levels) to H. influenzae and meningococcus C polysaccharides in the White children.

Antibodies, Bacterial↗