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Biomedical subjects

M J Lyons

Publications and source records attributed to M J Lyons.

At least 91 records · Page 5Linked to original sources
PubMed1985

Immunological relationships between Salmonella flagellins and between these and flagellins from other species of Enterobacteriaceae.

Ten antisera raised in rabbits, against polymeric flagellins from ten different Salmonella serotypes were used to determine the relative cross-activities between salmonella flagellins in monomeric form. The results showed a high degree of cross-reactivity between the antisera (IgG antibodies) and all monomeric flagellins investigated. Consequently, it was possible to detect the ten Salmonella serotypes, after heat depolymerization of flagella using radioimmunometric assay with only one antiserum raised against polymeric flagellin from one serotype. The results also showed that native flagella differed antigenically from repolymerized and monomeric flagellins. This is possibly due to changes in the tertiary structure of sub-units of flagella when depolymerized with acid or heat resulting in unfolding and unmasking of common antigenic determinants. The unfolded and unmasked antigenic determinants were not only common to the Salmonella serotypes investigated, but also to other members of Enterobacteriaceae.

Antibody Specificity↗
PubMed1985

Observable and subjective factors associated with attempted suicide in later life.

This paper presents the results of a case-control study of the relationship of socio-economic status (SES), relational system, service availability, perceived quality of life, and affective balance to attempted suicide. Subjects were white suicide attempters (N(7)34) and controls (N = 118) age 50 and above. Discriminant function analysis indicated that lower SES, less help available in a crisis, belonging to fewer organizations, and greater availability of services from a community mental health center were associated with classification as an attempter. Also, more negative emotions, fewer positive emotions, and dissatisfaction with oneself and one's finances predicted membership in the attempter group. The role of these factors as risk factors for and consequences of a suicide attempt is discussed.

Aged↗
PubMed1985

Rapid detection of salmonellae by immunoassays with titanous hydroxide as the solid phase.

Radioimmunometric and enzyme-immunometric assays were developed for the detection of salmonellae in pure and mixed cultures as well as in 59 food samples. The performances of titanous hydroxide suspension and microtiter plates as the solid phase for the immobilization of microorganisms were compared in these immunoassays. Detection of populations of salmonella cells in pure culture, diluted with saline, was 4- to 10-fold more sensitive with the microtiter plates. However, with mixed culture of salmonella and other enterobacterial species, the detection sensitivity with titanous hydroxide was 100- to 160-fold more sensitive than with microtiter plates. Good correlation existed between results of a standard cultural method for the detection of salmonellae in foods and those obtained from radioimmunometric and enzyme-immunometric assays utilizing titanous hydroxide. However, a high incidence of false-positive and false-negative results with food samples occurred with the enzyme-immunometric assay utilizing microtiter plates. The results provided strong evidence for the merits of substituting titanous hydroxide for microtiter plates as the solid phase for the immobilization of salmonellae for their detection by immunoassays. The immunoassays were rapid and enabled the analysis of a large number of selective enrichment cultures of food samples for salmonellae within 8 h.

False Negative Reactions↗
PubMed1985

Production of potent Salmonella H antisera by immunization with polymeric flagellins.

Highly purified polymeric flagellin preparations from 10 different Salmonella serotypes were used to produce specific Salmonella H antisera with high titers by the immunization of rabbits. Antigen emulsions in complete Freund adjuvant were administered at the rate of 50 micrograms per rabbit by multiple intradermal injection. Booster injections were given 110 days after the primary immunization. The immune response was monitored regularly over a period of 200 days. The results showed that the H titers, determined with 125I-labeled antigens, averaged 61,000 +/- 39,000, and the H agglutination titers of 83% of the animals were greater than 40,000. The high titers of the immunized animals persisted for approximately 4 months. The O agglutination titers of the antisera were less than 10 for 9 of the flagellin preparations and ranged from 10 to 320 for the remaining preparation. The antisera obtained were serotype specific after appropriate dilution.

Agglutination Tests↗
PubMed1985

Immobilization of microorganisms for detection by solid-phase immunoassays.

Several cultures of gram-negative and gram-positive bacteria were successfully immobilized with titanous hydroxide. The immobilization efficiency for the microorganisms investigated in saline and broth media ranged from 80.2 to 99.9%. The immobilization of salmonellae was effective over a wide pH range. The presence of buffers, particularly phosphate buffer, drastically reduced the immobilization rate. However, buffers may be added to immunoassay systems after immobilization of microorganisms. The immobilization process involved only one step, i.e., shaking 100 microliter of culture with 50 microliter of titanous hydroxide suspension in polystyrene tubes for only 10 min. The immobilized cells were so tenaciously bound that vigorous agitation for 24 h did not result in cell dissociation. The nonspecific binding of 125I-labeled antibody from rabbits and 125I-labeled protein A by titanous hydroxide was inhibited in the presence of 2% gelatin and amounted to only 5.6 and 3.9%, respectively. We conclude that this immobilization procedure is a potentially powerful tool which could be utilized in solid-phase immunoassays concerned with the diagnosis of microorganisms.

Bacteriological Techniques↗
PubMed1985

Method for the isolation of highly purified Salmonella flagellins.

Ten different Salmonella serotypes were grown in a chemically defined medium supplemented with 0.01% yeast extract. After sedimentation of the cells by centrifugation, flagella were detached by exposure to pH 2 for 30 min at room temperature. The flagellaless cells were removed by centrifugation, and the flagellin in the supernatant was further purified by high-speed centrifugation, ammonium sulfate precipitation, and dialysis in 50,000-molecular-weight-cutoff tubing. The 10 flagellin preparations were of a high degree of purity, as demonstrated by electron microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and measurement of salmonella H and O agglutination titers of antisera raised in rabbits with the flagellin preparations as immunogens.

Antigens, Bacterial↗
PubMed1984

Decisional processing in paranoid and non-paranoid schizophrenics.

40 schizophrenic subjects, divided into paranoid/non-paranoid categories and 14 normal controls were presented a task which involved making "same-different" judgments during random presentations of a series of visual comparison stimuli with a standard which represented the midpoint of the stimulus continuum. Using Sternberg's Choice RT paradigm for studying the locus of cognitive deficit, difficulty at the response-selection stage was manipulated while holding other stages constant. It was predicted that paranoids would have shorter RTs at easy decision points and longer RTs at difficult decision points relative to non-paranoids. The directions of the differences were as predicted but did not attain statistical significance. Both schizophrenic groups, compared to normals, made significantly fewer "same" responses on those trials where the comparison and standard were most similar.

Color Perception↗
PubMed1982

A virally induced obesity syndrome in mice.

An obesity syndrome was found in a number of mice infected as young adults with canine distemper virus, a morbillivirus antigenically related to measles. Body weights of obese animals 16 to 20 weeks after infection were comparable to those reported for genetically obese mice and for mice rendered obese by hypothalamic lesions. The total number of adipocytes in specific fat deposits was greater in obese animals than in their lean littermates. This hyperplasia was accompanied by moderate cell enlargement. Pancreatic islet tissue was also hypercellular in the obese mice. Brain tissue from the obese mice showed no overt pathology, and immunofluorescence staining for viral antigens was negative. There may be a selective, virus-induced disruption of critical brain catecholamine pathways.

Adipose Tissue↗
PubMed1982

Histologic and hemodynamic effects of prostacyclin and prostaglandin E1 following oleic acid infusion.

The hemodynamic and histologic effects of exogenous prostacyclin (PGI2) and prostaglandin E1 (PGE1) on oleic acid-induced acute respiratory failure were investigated. Adult mongrel dogs infused with oleic acid were treated with saline solution, PGE1, and PGI2. Significantly lowered blood pressure, systemic and pulmonary vascular resistance, and arteriovenous oxygen difference and preservation of preoleic cardiac output were observed in the pGI2 group. Compared with the saline group, only the arteriovenous oxygen difference was improved with PGE1. Light microscopy revealed acute edema and inflammation in the saline- and PGE1-treated lungs. Histologic specimens in the PGI2 group were normal.

Animals↗
PubMed1980

Induction of chronic neurologic disease in mice with canine distemper virus.

The capacity of a mouse-adapted strain of canine distemper virus (CDV) to induce central nervous system (CNS) disease in weanling mice was investigated. Lethality of infection was found to be mouse-strain-dependent. In sensitive strains, an acute meningoencephalomyelitis developed. Brain tissue from acutely ill animals demonstrated numerous foci of viral antigen, and extracts yielded infectious virus. Mice of resistant strains, notably the SJL strain, survived the effects of acute infection, appeared well for several weeks, and then began to develop signs of subacute CNS disease. Preliminary histopathologic examination of brain and cord from acutely ill animals revealed prominent perivascular mononuclear cell infiltrates, mononuclear cell meningitis, and gliosis. These features were also found in the subacute disease, where, however, the lesions were less severe. Also, in the latter, virus antigen could not be demonstrated. The results indicate that CDV infection of mice may provide a promising model system for the study of virus-induced chronic CNS disease.

Animals↗
PubMed1970

Biochemical consequences of type 2 adenovirus and Simian virus 40 double infections of African green monkey kidney cells.

African green monkey kidney (AGMK) cells were nonpermissive hosts for type 2 adenovirus although the restriction was not complete; when only 3 plaque-forming units/cell was employed as the inoculum, the viral yield was about 0.1% of the maximum virus produced when simian virus 40 (SV40) enhanced adenovirus multiplication. The viral yield of cells infected only with type 2 adenovirus increased as the multiplicity of infection was increased. Type 2 adenovirus could infect almost all AGMK cells in culture; adenovirus-specific early proteins and DNA were synthesized in most cells, but small amounts of late proteins were made in relatively few cells. Even when cells were infected with both SV40 and adenovirus, only about 50% were permissive for synthesis of adenovirus capsid proteins. Approximately the same quantity of adenovirus deoxyribonucleic acid (DNA) was synthesized in the restricted as in the SV40-enhanced infection. However, in cells infected with SV40 and type 2 adenovirus, replication of SV40 DNA was blocked, multiplication of SV40 was accordingly inhibited, and synthesis of host DNA was not stimulated. To enhance propagation of type 2 adenovirus, synthesis of an early SV40 protein was essential; 50 mug of cycloheximide per ml prevented the SV40-induced enhancement of adenovirus multiplication, whereas 5 x 10(-6)m 5-fluoro-2-deoxyuridine did not abrogate the enhancing phenomenon.

Adenoviridae↗