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Biomedical subjects

J Swanson

Publications and source records attributed to J Swanson.

At least 145 records · Page 8Linked to original sources
PubMed1979

Effects of methylphenidate (Ritalin) on selective attention in hyperactive children.

This study investigated the effect of methylphenidate (Ritalin) on the selective attention of hyperactive children designated as favorable or adverse responders to stimulant medication. Using a type II incidental learning paradigm, it was found that children in the drug condition recalled more central and less incidental stimuli than those children in the placebo condition. While no differential effects on recall were found for responder type, methylphenidate did affect the spontaneous overt labeling of central stimuli by the favorable responder group. Results were interpreted in terms of the role of methylphenidate in narrowing the focus of attention. Implications for the classification of hyperactive children as favorable and adverse responders were also discussed.

Attention↗
PubMed1979

Studies on gonococcus infection. XVII. IgA1-cleaving protease in vaginal washings from women with gonorrhea.

Vaginal washings from women attending a veneral disease clinic were examined for the presence of protease that cleaved IgA subclass 1 (IgA1). In a crude assay, vaginal washings cleaved [125I]IgA1 in 19 of 25 specimens from individuals from whom Neisseria gonorrhoeae were cultivated. Forty-six specimens from 104 women whose cultures were negative for N. gonorrhoeae also cleaved [125I]IgA1. Vaginal washings from six of six women with culture-proven gonorrhea cleaved [125I]IgA1 into low-molecular-weight components identical to those produced by partially purified IgA1-specific protease from gonococci. The hydrolysis of [125I]IgA1 by vaginal washings from women whose cultures were negative for N. gonorrhoeae yielded cleavage products that resembled those of trypsin or alpha-chymotrypsin. These findings indicate that gonococci residing in the female genital tract produce IgA1-specific protease that can be detected in the vaginal washings of infected women.

Electrophoresis, Polyacrylamide Gel↗
PubMed1979

Studies on gonococcus infection. XVIII. 125I-labeled peptide mapping of the major protein of the gonococcal cell wall outer membrane.

The major outer membrane proteins from 10 gonococcal strains were examined after 125I-labeling of the proteins as single bands resolved by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. These 125I-proteins were then treated with either trypsin or alpha-chymotrypsin, and the resultant 125I-peptides were visualized by autoradiography after two-dimensional electrophoretic and chromatographic separation on thin-layer cellulose sheets. Several 125I-peptides were present in all the major outer membrane proteins examined. The presence and absence of additional 125I-peptides segregated the major proteins into two pattern groups. One group consisted of major outer membranes with molecular weights of 34,000 or 33,000; major proteins with molecular weights of 32,000 constituted the other group. Two beta-lactamase-producing gonococcal isolates were examined. Their major outer membrane proteins were identical in apparent molecular weights and alpha-chymotryptic 125I-peptide fingerprints; these proteins contained 125I-peptides not found in other gonococcal major proteins. No 125I-peptide differences were found among the major outer membrane proteins of strain F62 gonococci that exhibited differences in piliation and/or colony opacity characteristics.

Bacterial Proteins↗
PubMed1978

Studies on gonococcus infection. XI. Comparison of in vivo and vitro association of Neisseria gonorrhoeae with human neutrophils.

The levels of association between Neisseria gonorrhoeae and neutrophils as determined by microscopic study of smears of urethral exudate from men with acute gonorrhea and by in vitro assay of N. gonorrhoeae cultivated from those same individuals showed statistically significant correlation. The percentage of N. gonorrhoeae attached to or ingested by neutrophils varied from 30% to 90% in the clinical smears. Neither the apparent in vivo nor the in vitro association with neutrophils could be correlated with piliation of the N. gonorrhoeae studied.

Gonorrhea↗
PubMed1978

Studies on gonococcus infection. XII. Colony color and opacity varienats of gonococci.

Colonies with markedly differing color and opacity characteristics were found for Neisseria gonorrhoeae propagated on translucent, solid medium. These optical properties of gonococcal colonies were independent of pilation and appeared to be related to the degree of aggregation among the gonococci comprising the colonies. Dark, opaque colonies contained highly aggregated gonococci which were more susceptible to killing and to solubilization of their 125-labeled surface components than were organisms comprising light, transparent colony forms.

Cell Wall↗
PubMed1978

Studies on gonococcus infection. XIII. Occurrence of color/opacity colonial variants in clinical cultures.

Colonial variants of Neisseria gonorrhoeae differing in color and opacity characteristics are distributed differently between male urethral and female cervical cultures. Colonial characteristics of cultures isolated from female cervices differ with time of isolation within the menstrual cycle and use of oral contraceptives. These differences may reflect selective forces in the ecology of the cervix, particularly proteolytic enzymes in cervical mucus and menstrual blood. Cycle changes in the characteristics of gonococci isolated from females may have implications for pathogenesis of gonococcal infections and immune response to the gonococcus.

Cervix Uteri↗
PubMed1978

Studies on gonococcus infection. XIV. Cell wall protein differences among color/opacity colony variants of Neisseria gonorrhoeae.

Gonococci from colonies exhibiting optical opacity and dark coloration have surface proteins that are not visualized in isogenic transparent, light-colored colony forms. These "colony opacity-associated proteins" have apparent molecular weights varying from 24,000 to 30,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate; their apparent molecular weights are independent of that for their major outer membrane protein. The opacity-associated proteins are more susceptible to hydrolysis by trypsin than is the major outer membrane protein, but gonococci possessing the opacity-associated protein(s) also show enhanced susceptibility of their major outer membrane proteins to the action of trypsin. These conclusions were reached by comparing the electrophoretic patterns of whole-cell lysates from both "laboratory strains" and several recent clinical isolates of Neisseria gonorrhoeae.

Autoradiography↗
PubMed1978

Studies on gonococcus infection. XV. Identification of surface proteins of Neisseria gonorrhoeae correlated with leukocyte association.

Neisseria gonorrhoeae which exhibit high levels of leukocyte association have a surface protein which is considerably diminished in isogenic gonococci which exhibit low levels of leukocyte association (LA). The LA protein exhibits strain variation in molecular weight and immunogenicity. Membranes derived from LA+ and LA- organisms show quantitative differences in their adsorption to leukocytes; these differences are analogous to those found for the intact organisms regarding their association with leukocytes.

Animals↗
PubMed1978

Studies on gonococcus infection. XVI. Purification of Neisseria gonorrhoeae immunoglobulin A1 protease.

A protease which cleaves human immunoglobulin A1 (IgA1) has been purified from broth cultures of Neisseria gonorrhoeae. This IgA1 protease is produced by pilated and nonpilated gonococci throughout their growth cycles. A combination of ammonium sulfate precipitation, column chromatography, and either isoelectric focusing or affinity chromatography was utilized to obtain an enzyme preparation that showed approximately 3,800-fold purification and exhibited two bands (65,000 and 70,000 daltons) by analytical polyacrylamide electrophoresis in the presence of sodium dodecyl sulfate and reducing conditions. IgA1 protease activity is dependent on divalent cations and is heat labile. Detection and quantitation of IgA protease activity utilized an assay in which [125I]IgA1 is incubated with protease preparations and the cleavage products are analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Female↗
PubMed1978

Time-response analysis of the effect of stimulant medication on the learning ability of children referred for hyperactivity.

This report introduces a method for obtaining behavioral time-response information for a short-acting psychotropic drug (methylphenidate [Ritalin]) that is widely used to treat behaviorally hyperactive children. We used a laboratory learning task to document that between one and two hours after the administration of a single dose of methylphenidate, the drug exerts its maximum effect on performance in a learning task in the laboratory. This effect on cognitive performance dissipates within the same day. This rapid and transient effect of methylphenidate makes it possible to classify patients in a single day into those who respond favorably and those who respond adversely to the drug in terms of its effect on cognitive behavior.

Association Learning↗
PubMed1977

The capsule of the gonococcus.

16 strains of Neisseria gonorrhoeae were subjected to several established techniques for capsule demonstration by light microscopy. In all strains examined, encapsulation of the gonococcus was demonstrated. Although the capsules were somewhat more easily seen in strains recently isolated from clinical material, organisms that had been passaged for several years also were encapsulated as were all the colony types within these strains. The gonococcal capsule is easily disrupted by mechanical forces.

Microscopy↗
PubMed1977

Surface components affecting interactions between Neisserai gonorrhoeae and eucaryotic cells.

Interactions of Neisseria gonorrhoeae with nonleukocytic eucaryotic cells including tissue culture cells (either primary or continuous lines), human sperm, and buccal mucosal cells appear to be influenced primarily by the presence or absence of pili on the bacteria. In this context, piliation enhances attachment to or association of microorganisms with the eucaryotic cells. Pili, on the other hand, appear to reduce interaction of N. gonorrhoeae with mouse peritoneal macrophages. Other groups have demonstrated that pili reduce phagocytosis of gonococci by neutrophils, but in out studies this affect is secondary to that dependent on "leukocyte-association" factor. The presence of such a factor is correlated with a particular protein found by polyacrylamide electrophoresis. Adherence among N. gonorrhoeae varies and results in colony forms of different coloration or aggregation characteristics. These different coloration forms correlate with the protein patterns of gonococci as found in polyacrylamide electrophoresis and also with the susceptibility of gonococci to killing by trypsin.

Bacterial Proteins↗
PubMed1977

Transient LW-negative red blood cells and anti-LW in a patient with Hodgkin's disease.

LW-negative (LW4) red blood cells and anti-LW antibody were discovered in the blood of a 50-year-old white male with Hodgkin's disease and blood type O. Compatible red blood cells for transfusion could not be obtained because available LW-negative cells were either type A, LW4, or type O, LW3. Following cytotoxic therapy for his basic disease, the anti-LW disappeared and his red blood cells developed normal reactions with anti-LW sera.

Blood Group Incompatibility↗