Effects of food-related stimuli on visual spatial attention in fasting and nonfasting normal subjects: Behavior and electrophysiology.

OBJECTIVE: Attention biases toward food-related stimuli were examined as mediators of normal, healthy motivated behavior. METHODS: Reaction times (RTs) and event-related potentials (ERPs) were used to assess the impact of food-related words on normal food-deprived individuals when used as spatial cues that frequently predicted the location of targets in a simple detection task (75% validity). RESULTS: In Experiment 1, fasting and nonfasting subjects showed a magnified cost/benefit of invalid/valid cueing by food words relative to a neutral category of words. In Experiment 2, the RT effect was replicated in a group of fasting subjects. The amplitude of a P3-like positivity (P420) was enhanced in response to food words, as was that of a prominent early anterior negativity (AN). CONCLUSIONS: These findings demonstrate that food-related stimuli can bias spatial attention in normal subjects and that electrophysiological markers can index the motivational salience of food words and/or their effect on attentional capture in food-deprived individuals. SIGNIFICANCE: Even when the motivational salience of spatial cues is irrelevant to task demands, it can have an observable effect on attention. This design allows for the behavioral and electrophysiological study of motivation-attention interactions through loading of spatial cues with motivation-related semantic properties.

Performance of Meridian ImmunoCard Mycoplasma test in a multicenter clinical trial.

Serology is the principal laboratory method used to diagnose Mycoplasma pneumoniae infection. Meridian Diagnostics has developed the ImmunoCard Mycoplasma kit, a 10-min card-based enzyme-linked immunosorbent assay (ELISA) designed to detect immunoglobulin M (IgM) antibodies to M. pneumoniae. We compared the ImmunoCard with two M. pneumoniae IgM-specific assays (immunofluorescence assay [IFA] and ELISA) and a standard complement fixation (CF) procedure using 896 specimens submitted to clinical laboratories for M. pneumoniae serology. Equivocal results obtained by CF, IFA, or ELISA were resolved by testing with an additional method or by reviewing patient chart information. The ImmunoCard had sensitivities ranging from 74% compared with the ELISA to 96% compared with CF results with IFA. ImmunoCard specificities ranged from 85% compared with the IgM-specific ELISA to 98% compared with IgM-specific IFA results resolved with clinical chart review. We also compared the ImmunoCard results with consensus results of 694 specimens tested on at least two non-ImmunoCard methods because of the lack of a "gold standard" for M. pneumoniae serology. Overall, the ImmunoCard Mycoplasma IgM assay had 90% sensitivity, 93% specificity, and 92% agreement with the consensus results. The ImmunoCard is technically less complex and requires less equipment that the three other assays. Our results indicate that the ImmunoCard Mycoplasma IgM assay is a valid and simple procedure which can reduce technologist time (and, thus, labor cost) and turnaround time for laboratories analyzing small numbers of specimens (< 10 per batch) submitted for IgM anti-M. pneumoniae testing.

Laboratory diagnosis of viral infections of the lung.

Over the past 10 years the diagnosis of viral pneumonias and other infections of the respiratory tract has been greatly facilitated by the application of new biotechnology. Molecular and immunologic techniques have been developed for the detection of viral nucleic acids and proteins in clinical materials obtained from the lung, either by bronchoalveolar lavage or biopsy. Clinicians are now able to obtain a virologic diagnosis with a high degree of sensitivity and specificity, often within a few hours of the diagnostic procedure. We review the current status of the newer molecular and immunologic modalities being applied to the rapid laboratory diagnosis of viral infections of the lung, including direct and indirect fluorescent antibody staining of material from the respiratory tract, enzyme immunoassays, centrifugation cultures, and molecular techniques, such as the polymerase chain reaction. These techniques permit the rational use of specific antiviral therapeutic agents in patients with drug-sensitive pulmonary viral infections, thus improving both morbidity and mortality.

Comparison of the Seradyn Color Vue passive agglutination test and complement fixation for detection of Mycoplasma pneumoniae antibodies.

We compared traditional complement fixation (CF) with a new passive agglutination method, the Seradyn Color Vue (SCV) test (Seradyn, Indianapolis, Ind.), for detection of Mycoplasma pneumoniae antibodies in 170 stored serum samples. The SCV test was 90% sensitive in identifying as positive 27 of 30 CF high-titer (> or = 1:64) serum samples and 100% specific in identifying as negative 134 of 134 CF low-titer (< or = 1:32) or negative (< 1:8) serum samples. The SCV test was technically undemanding, and it required no expensive equipment.

Evaluation of the L-CLONE Legionella pneumophila Serogroup 1 Urine Antigen Latex Test.

The purpose of this study was to evaluate the L-CLONE Legionella pneumophila Serogroup 1 Urine Antigen Latex Test (Access Medical Systems, Inc., Branford, Conn.) for detection of Legionella antigen in urine. A total of 481 frozen urine samples previously tested by an in-house solid-phase radioimmunoassay (RIA) was thawed and retested by using L-CLONE. Included in this sample were 140 RIA-positive samples from culture-positive or serologically confirmed cases of legionellosis and 341 RIA-negative samples from patients with non-Legionella respiratory disease or bacteriuria. The original RIA test result was accepted as the true value. L-CLONE correctly identified 76 of 140 (54%) known positive samples. False-negative results could not be attributed to a low Legionella antigen concentration or to a Legionella antigen subgroup. L-CLONE correctly identified 252 of 341 (74%) known negative samples. False-positive results were experienced in all groups of negative samples, regardless of the patients' underlying diseases. A total of 141 fresh urine samples was tested; all were Legionella antigen negative by RIA. L-CLONE provided 86% specificity. The sensitivity of the L-CLONE in testing fresh urine samples could not be evaluated because of the lack of Legionella antigen RIA-positive samples.

Variability in commercial histoplasma complement fixation antigens.

Using Immuno-Mycologics (IMMY; Norman, Okla.) histoplasmal yeast (HY) and mycelial (HM) antibody complement fixation test antigens, we retested 1,386 samples that were initially tested with Meridian Diagnostics, Inc. (Cincinnati, Ohio), antigens. Histoplasma antibody was identified (greater than or equal to 1:16) in 20% of HY and 5% of HM samples reported to have titers of less than 1:8 with Meridian reagents. IMMY titers were at least fourfold higher than Meridian titers in 39% of HY and 54% of HM samples that initially had titers of greater than or equal to 1:8 with Meridian antigens. Because 30 of 58 (52%) samples from confirmed cases of histoplasmosis yielded negative results with Meridian antigens and positive results upon retesting with IMMY antigens, we concluded that the Meridian antigens had less reactivity with human histoplasmal antibody.

Clinical experience with cytomegalovirus isolation using conventional cell cultures and early antigen detection in centrifugation-enhanced shell vial cultures.

A total of 1,915 clinical samples was inoculated by low-speed centrifugation into shell vials (Bartels Immunodiagnostics, Bellvue, Wash.) containing cover slip monolayers of MRC-5 fibroblasts. At 1 and 2 days postinoculation, one cover slip was stained by an indirect immunofluorescence technique using a monoclonal antibody (Biotech Research Laboratories for Dupont, Billerica, Mass.) to cytomegalovirus (CMV) early antigen (EA). Clinical samples were also inoculated into three MRC-5 or MRHF cell cultures which were observed for 30 days for the appearance of a cytopathic effect (CPE). Of 157 CMV-positive samples, 92 (59%) were identified by centrifugation-enhanced EA (CE-EA) and 131 (83%) produced a CPE. CE-EA was less sensitive than CPE for all types of samples, although 17% of CMV-positive samples were detected by CE-EA alone. Evaluation of the CMV status of patients with CE-EA-positive-CPE-negative samples indicated that these samples likely represented true CMV-positive results. The average elapsed time between culture inoculation and identification of CMV decreased as follows when both CE-EA and CPE, rather than CPE alone, were used: urines, 15 to 7 days; buffy coats, 18 to 9 days; lung samples, 13 to 8 days; throat samples, 18 to 7 days. Although CE-EA was less sensitive than 30-day cell culture, both CE-EA and CPE were identified as valuable in CMV detection, and neither could be discontinued without a decrease in the CMV isolation rate or an increase in the turnaround time.

Evaluation of four methods for cytomegalovirus antibody detection for use by a bone marrow transplantation service.

Four methods, latex agglutination, indirect fluorescent antibody, enzyme immunoassay, and complement fixation, were compared for cytomegalovirus antibody screening and for pre- and posttransplant determinations on bone marrow transplant recipients. Latex agglutination was most sensitive (98%) and specific (97%) for screening and pretransplant determinations and was quickest and easiest to perform. In posttransplant sera from allogeneic bone marrow transplant recipients, all methods except complement fixation detected cytomegalovirus antibody from therapeutically administered globulin preparations; this made it difficult to determine the significance of changes in cytomegalovirus antibody titer.

Comparative evaluation of media for isolation of ureaplasma urealyticum and genital mycoplasma species.

Two media systems were compared for isolation of Ureaplasma urealyticum and genital Mycoplasma sp. System 1 (S-1) consisted of arginine agar and an arginine biphasic medium for isolation of Mycoplasma sp. and urea agar and urea broth for isolation of U. urealyticum. System 2 (S-2) utilized Boston broth, which is a urea-containing broth, and A7 agar, both of which support the growth of both species. Urine samples, some freshly collected and some known-positive frozen samples, were used as inocula for the two media systems. With S-1, U. urealyticum was recovered in 68% of U. urealyticum-positive cultures: 58% were detected in urea broth, and 60% were identified on urea agar. When the S-2 system was used for culture of the same samples. U. urealyticum was recovered in 98% of the cultures, with 94% detected in Boston broth and 92% identified on A7 agar. Mycoplasma sp. was recovered in S-1 and S-2 in 97 and 100% of Mycoplasma sp.-positive cultures, respectively. The S-1 arginine broth gave positive results for 89% of the cultures, and the arginine agar was positive for 97% of the cultures. The S-2 Boston broth and A7 agar gave positive results for 92 and 97% of the cultures, respectively. For the isolation of U. urealyticum, colony counts were higher, growth was seen sooner, and colonies were larger when the S-2 media system was used. Overall, the cost per test of the S-2 system was less both in technologist time and in reagent costs.

Method for rapid detection of group B streptococci by coagglutination.

A quick and reliable technique for the identification of group B streptococci has been developed. The method requires no elaborate equipment or expensive reagents and can be used to detect the group B organisms in mixed broth cultures or to identify suspect colonies selected from agar plates. The method is a coagglutination technique in which 1 drop of specifically sensitized protein A-containing Staphylococcus aureus is mixed with 1 drop of supernatant of an actively growing culture. The soluble group-specific carbohydrate substance of the group B streptococci reacts with the staph particles to produce agglutination that is macroscopically readable. One colony of group B streptococci taken from an agar plate and inoculated into Todd-Hewitt broth will give a positive reaction within 6 h of incubation; with a larger inoculum, the positive reaction occurs within a shorter period. The method was applied for detection of group B streptococci in mixed broth cultures. In laboratory studies involving random mixtures of organisms, 59.3% of positive cultures were detected within the first 8 h of incubation, and 71.7% were found within 24 h. In clinical studies with mixed broth cultures grown directly from vaginal swabs, 78.6% of the positive cultures were detected within the first 8 h of incubation, and 92.9% were found within 24 h.