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Biomedical subjects

J Swanson

Publications and source records attributed to J Swanson.

At least 163 records · Page 9Linked to original sources
PubMed1975

Light and electron microscopic study of Chlamydia trachomatis infection of the uterine cervix.

Cervical biopsy specimens from two patients with infections caused by Chlamydia trachomatis (TRIC agent) were studied by means of light and electron microscopy. Intraepithelial vesicles containing C. trachomatis were present in the cervical mucosa. These intramucosal vesicles were readily recognized in paraffin sections by means of light microscopy. The developmental stages of C. trachomatis, which have previously been seen in tissue cell culture, chicken embryo, and conjunctival infections, were also apparent in cervical infection.

Antibodies, Bacterial↗
PubMed1975

Studies on gonococcus infection. VII. In vitro killing of gonococci by human leukocytes.

The comparative killing of pilated and nonpilated forms of Neisseria gonorrhoeae by human peripheral blood leukocytes was studied in vitro. Some nonpilated gonococci (T2) were killed to a lesser extent than were pilated, T2 organisms, which were killed less readily than another nonpilated (T4*) form of gonococcus. Thus, the relative order of killing of gonococci by human peripheral blood leukocytes appears to be: T4 less than T2 less than T4*. These data suggest that pilation, though correlated with virulence of gonococci, has little influence on the survival or killing of these organisms by human leukocytes.

Bacteriological Techniques↗
PubMed1975

Studies on gonococcus infection. VIII. 125Iodine labeling of gonococci and studies on their in vitro interactions with eukaryotic cells.

Intact gonococci (GC) have been labeled with 125iodine by the lactoperoxidase plus hydrogen peroxide procedure. The specific activities of types 2, 4, and 4 GC have been determined and are found to show small differences as follows: T4 greater than T2 greater than T4. 125I-labeled GC have been studied for their associations with both leukocytes and tissue culture cells. 125I-labeled GCshow the following relative order of association with the leukocytes: T2 equals T4* greater than T4. This contrasts with the relative degree of interaction between the GC and tissue culture cells, which follows the relative order: T2 greater than T4 equals T4*. Trypsin pretreatment of GC markedly reduces the association of all three types (T2, T4 AND T4*) with leukocytes but does not alter the level of attachment of any of the gonococcal types with tissue culture cells.

Culture Techniques↗
PubMed1974

Studies on gonococcus infection. V. Observations on in vitro interactions of gonococci and human neutrophils.

The association of in vitro human leukocytes with pilated, type 2 Neisseria gonorrhoeae exceeds that for nonpilated, type 4 organisms but is less than that for nonpilated, type 4(*) gonococci. The two nonpilated forms of gonococci (types 4 and 4(*)) attach to tissue culture cells to a much lesser extent than do pilated, type 2 organisms of the same strain. Trypsin treatment of either pilated (type 2) or nonpilated (type 4(*)) gonococci markedly reduces the attachment-ingestion of these organisms with leukocytes, but the same trypsin treatment does not depilate the type 2 organisms nor visibly alter the morphology of their pili. Similar reductions in association with leukocytes are found if the gonococci are pretreated with chymotrypsin, heat, or glutaraldehyde. High levels of association between gonococci and leukocytes are reestablished if the trypsin or chymotrypsin-treated organisms are reincubated in protease-free medium. These data suggest that interactions between gonococci and human neutrophils are mediated through surface characteristics of the bacteria, different from those which influence attachment of the organisms to tissue culture cells. In the latter instance, pili appear to positively influence gonococcal attachment, whereas in the former a nonpilus bacterial cell wall nonpilus protein is probably the major determiner in the interaction between leukocytes and gonococci.

Carbon Radioisotopes↗
PubMed1974

Studies on gonococcus infection. VI. Electron microscopic study on in vitro phagocytosis of gonococci by human leukocytes.

The ingestion of Neisseria gonorrhoeae by isolated human leukocytes in vitro has been studied by electron microscopy. Use of the modified critical-point drying method allows clear visualization of progressive ingestion of both pilated and nonpilated gonococci by leukocytes. Incomplete ingestion of pilated gonococci with protrusion of tangled masses of pili from sites of phagocytosis are also found.

Histological Techniques↗
PubMed1974

Differential attachment by piliated and nonpiliated Neisseria gonorrhoeae to human sperm.

Piliated type 1 Neisseria gonorrhoeae attached to 50% of human sperm after incubation of mixtures in vitro for 15 min at 35 C. In contrast, nonpiliated type 4 N. gonorrhoeae attached to only 23% of sperm. Similar results were obtained with three different strains of N. gonorrhoeae. Treatment with heat or formaldehyde to kill bacteria did not affect the amount of attachment by piliated or nonpiliated types. Escherichia coli and N. subflava, other species of piliated bacteria, attached to about 40% of sperm, and the nonpiliated species N. meningitidis and N. catarrhalis attached to a comparable number of sperm, as did type 4 N. gonorrhoeae. Prior incubation of type 1 N. gonorrhoeae with purified antibody prepared against gonococcal pili reduced the percentage of sperm with attached bacteria to the same level as that for nonpiliated type 4 gonococci. Similar treatment of other piliated organisms or of nonpiliated Neisseria did not affect the attachment of the bacteria to sperm.

Animals↗
PubMed1973

Electron microscopic studies on streptococci. II. Group A carbohydrate.

The location of Group A carbohydrate in the streptococcal cell wall has been studied by several ultrastructural techniques. The findings, based largely on use of ferritin- and horseradish peroxidase-conjugated antibodies, are interpreted as demonstrating a discrete laminar distribution of the group-specific polysaccharide. This carbohydrate layer is located on the outermost surface of the cell wall in organisms lacking protein cell wall antigens.

Animals↗
PubMed1973

Studies on gonococcus infection. IV. Pili: their role in attachment of gonococci to tissue culture cells.

Attachment of Neisseria gonorrhoeae to amnion cells in tissue culture is facilitated if the gonococci bear pili. This has been determined by studying the number of pilated, colony type 2 gonococci associated with amnion cells after incubation in vitro as compared with the number of nonpilated, colony type 4 gonococci present with amnion cells under the same conditions. These data are supported by light microscope findings. Electron microscope studies provide visualization of fine structure of gonococcal attachment. Gonococci are also found within amnion cells in this in vitro system.

Amnion↗
PubMed1973

Quantitative determination of antibody to gonococcal pili. Changes in antibody levels with gonococcal infection.

Gonococcal pili, pure by the criteria of electron microscopic examination and polyacrylamide gel electrophoresis in sodium dodecyl sulfate, have been prepared by repeated cycles of precipitation with 0.1 M MgCl(2), followed by dissolution in 0.01 M Tris pH 8, 0.01 M NaN(3). Using a fluorescein-conjugated antibody prepared to pili from a single strain, pilar antigen(s) was found to be present in each of 18 strains of gonococci tested, and absent from strains of pilated meningococci, nonpathogenic Neisseria sp., and Escherichia coli. Purified pili, labeled with (125)I were used in an antigen binding assay to quantitatively measure antibody to pili in rabbit sera and in 561 human sera. The range of antibody activity for 133 persons unlikely to have experienced gonorrhea was 0.1-1.6 mug/ml with a geometric mean of 0.5 mug/ml. This geometric mean antibody activity was significantly lower than the geometric mean for asymptomatically infected males (1.0 mug/ml, P < 0.002), males with symptomatic gonococcal anterior urethritis (1.6 mug/ml, P < 0.001), or asymptomatically infected females (4.2 mug/ml, P < 0.001). Antibody appeared in elevated levels (> 1.6 mug/ml) 2-3 wk after infection and returned toward control levels 1 or more months after treatment. Antibody levels higher than 1.6 mug/ml were found in 26 (50%) of 52 males with gonococcal anterior urethritis, in 10 (33%) of 30 males with asymptomatic urethral infection and in 50 (89%) of 56 asymptomatically infected females. In a high-risk group of 103 females for whom culture results and antibody to pili were compared, 58 (57%) had elevated antibody levels to pili and 86% of the infected females were within this seropositive group. The antigen binding assay may provide a means to detect asymptomatic gonococcal infection in women.

Adolescent↗
PubMed1972

Studies on gonococcus infection. II. Freeze-fracture, freeze-etch studies on gonocci.

Gonococci have been studied by electron microscopy after freeze-cleavage, freeze-etching and the findings correlated with those obtainable through thin sectioning and negative staining. The outer membrane of the cell wall is composed of round to hexagonal subunits 80 A in diameter. This membrane is also punctuated by 80-A holes visible on the exterior of the organism and extending into the substance or through the outer membrane. Pili coursing over the surface of the organisms appear to maintain a close anatomical relationship with the cell wall. In some instances, the surfaces of the organisms are virtually covered by a layer of pili.

Cell Wall↗
PubMed1971

Studies on gonococcus infection. I. Pili and zones of adhesion: their relation to gonococcal growth patterns.

The four colony types of several different strains of gonococci were isolated by selective transfers on agar. These colony variants differed in the degree of autoagglutination which occurred when they were grown in fluid medium. It was found that this clumping behavior was related to the colonial type, with type 2 isolates exhibiting the greatest autoagglutination followed by types 3, 1, and 4. Electron microscopic examination of thin sections indicated that the clumping in fluid medium was mediated by peculiar zones of adherence of the outer membranes of gonococci. These resembled the gap junctions seen in animal cell systems but differed in that the gonococcal membranes involved in the zone of adherence did not bear typical surface modifications. Electron microscopic study of negatively stained specimens of gonococci revealed that pili with a diameter of approximately 85 A and a length up to 4 micro were present on the surfaces of all type 1 and type 2 gonococci examined, and were not seen on any type 3 or 4 gonococci. The consistent presence of pili on type 1 and type 2 gonococci which are virulent colony forms and the lack of pili on avirulent colony types 3 and 4 suggests a relationship between the gonococcal pili and pathogenetic potential of the organisms.

Agar↗