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D W McLaughlin

Publications and source records attributed to D W McLaughlin.

12 recordsLinked to original sources
PubMed2000

Comparison of commercial latex agglutination and sandwich enzyme immunoassays with a competitive binding inhibition enzyme immunoassay for detection of antigenemia and antigenuria in a rabbit model of invasive aspergillosis.

A commercial latex agglutination assay (LA) and a sandwich enzyme immunoassay (SEIA) (Sanofi Diagnostics Pasteur, Marnes-la-Coquette, France) were compared with a competitive binding inhibition assay (enzyme immunoassay [EIA]) to determine the potential uses and limitations of these antigen detection tests for the sensitive, specific, and rapid diagnosis of invasive aspergillosis (IA). Toward this end, well-characterized serum and urine specimens were obtained by using a rabbit model of IA. Serially collected serum or urine specimens were obtained daily from control rabbits or from rabbits immunosuppressed and infected systemically with Aspergillus fumigatus. By 4 days after infection, EIA, LA, and SEIA detected antigen in the sera of 93, 93, and 100% of A. fumigatus-infected rabbits, respectively, whereas antigen was detected in the urine of 93, 100, and 100% of the rabbits, respectively. False-positive results for non-A. fumigatus-infected rabbits for EIA, LA, and SEIA were as follows: for serum, 14, 11, and 23%, respectively; for urine, 14, 84, and 90%, respectively. Therefore, although the sensitivities of all three tests were similar, the specificity was generally greater for EIA than for LA or SEIA. Infection was also detected earlier by EIA, by which the serum of 53% of A. fumigatus-infected rabbits was positive as early as 1 day after infection, whereas the serum of only 27% of the rabbits tested by LA was positive. Although the serum of 92% of A. fumigatus-infected rabbits was positive by SEIA as early as 1 day after infection, the serum of a high percentage (50%) was false positive before infection. The urine of 21% of A. fumigatus-infected rabbits was positive by EIA as early as 1 day after infection, and the urine of none of the rabbits was false positive before infection. When EIA results for urine specimens were combined with those for serum, sensitivity was improved (i.e., 67% of rabbits were positive by 1 day after infection and only one rabbit gave a false-positive result). A total of 93% of A. fumigatus-infected rabbits were positive for antigen in urine as early as 1 day after infection and the urine of 100% of the rabbits was positive by SEIA. However, before infection, 79% of A. fumigatus-infected rabbits were false positive for antigen in urine by LA and 90% were false positive for antigen in urine by SEIA. These data indicate that the EIA has the potential to be used to diagnose IA with both serum and urine specimens and to detect a greater number of infections earlier with greater specificity than the specificities achieved with the commercial tests.

Animals↗
PubMed1999

Spectral bifurcations in dispersive wave turbulence.

Dispersive wave turbulence is studied numerically for a class of one-dimensional nonlinear wave equations. Both deterministic and random (white noise in time) forcings are studied. Four distinct stable spectra are observed-the direct and inverse cascades of weak turbulence (WT) theory, thermal equilibrium, and a fourth spectrum (MMT; Majda, McLaughlin, Tabak). Each spectrum can describe long-time behavior, and each can be only metastable (with quite diverse lifetimes)-depending on details of nonlinearity, forcing, and dissipation. Cases of a long-live MMT transient state dcaying to a state with WT spectra, and vice-versa, are displayed. In the case of freely decaying turbulence, without forcing, both cascades of weak turbulence are observed. These WT states constitute the clearest and most striking numerical observations of WT spectra to date-over four decades of energy, and three decades of spatial, scales. Numerical experiments that study details of the composition, coexistence, and transition between spectra are then discussed, including: (i) for deterministic forcing, sharp distinctions between focusing and defocusing nonlinearities, including the role of long wavelength instabilities, localized coherent structures, and chaotic behavior; (ii) the role of energy growth in time to monitor the selection of MMT or WT spectra; (iii) a second manifestation of the MMT spectrum as it describes a self-similar evolution of the wave, without temporal averaging; (iv) coherent structures and the evolution of the direct and inverse cascades; and (v) nonlocality (in k-space) in the transferral process.

Atmosphere↗
PubMed1993

Purification and characterization of the extracellular aspartyl proteinase of Candida albicans: removal of extraneous proteins and cell wall mannoprotein and evidence for lack of glycosylation.

Aspartyl proteinase (AP) is an extracellular enzyme of Candida albicans implicated as a pathogenic factor. Previous reports on the purification and characterization of AP suggested that a single DEAE-Sephadex chromatographic step was sufficient for the removal of extraneous proteins and that the final product was glycosylated. We purified AP using a chromatographic series consisting of DEAE-Sephadex A25, Sephadex G75 and rechromatography on DEAE-Sephadex A25. Use of DEAE-Sephadex alone did not remove extraneous proteins and removed little contaminating mannoprotein (MP). The addition of a Sephadex G75 column to the purification scheme removed the majority of contaminating MP and proteins. The final DEAE-Sephadex A25 chromatographic step resulted in (a) removal of detectable extraneous proteins, (b) removal of immunologically detectable MP by dot blot and Western blot enzyme immunoassay, (c) loss of periodic acid-silver stain positivity, and (d) a high AP yield (1295 U l-1) and specific activity (1749 U mg-1). We conclude that a single DEAE-Sephadex A25 purification step is insufficient to remove extraneous proteins and MP, which could interfere with the production of AP-specific antibodies and the dissection of moieties responsible for immune reactivity. Reports of periodic acid-Schiff or anthrone positivity of AP preparations may reflect the presence of extraneous MP, which can be removed by the chromatographic series we describe.

Aspartic Acid Endopeptidases↗
PubMed1989

Indirect enzyme-linked immunosorbent assay for zygomycosis.

A 2-h indirect enzyme-linked immunosorbent assay (ELISA) using homogenate antigens of Rhizopus arrhizus and Rhizomucor pusillus was developed and compared with the existing immunodiffusion (ID) test for zygomycosis, using homogenate antigens of R. arrhizus. Utilizing 1:400 as a minimally positive ELISA titer, 33 of 43 proven cases of zygomycosis were diagnosed. The sensitivity of the ELISA was 81%. The ID test, in contrast, detected only 21 cases and demonstrated a sensitivity of 66%. The specificity of the ELISA was 94%, whereas that of the ID test was 91%. Nonspecific ELISA reactivity was particularly evident with sera from patients with aspergillosis and candidiasis. With the antigens now available, the ELISA was unable to generically or specifically identify the etiologic agents.

Antibodies, Fungal↗
PubMed1980

Characterization of antigens from Aspergillus fumigatus. V. Reactivity in immunodiffusion tests with serums from patients with aspergillosis caused by Aspergillus flavus, A. niger, and A fumigatus.

Antigen-rich mycelial extract (ME) and fractions of Aspergillus fumigatus were compared with culture filtrates of A. fumigatus. A. flavus, and A. niger for their abilities to detect antibody in serums from patients with confirmed aspergillosis caused by these fungi. In double immunodiffusion tests, homologous antigen preparations were more effective than heterologous preparations in detecting precipitins. Mycelial extract of A. fumigatus was more effective than A. fumigatus culture filtrate in detecting antibody in serums from patients with disease caused by A. flavus and A. niger. It did not, however, detect antibody in the serums from approximately half of the patients with heterologous infections.

Antibodies, Fungal↗
PubMed1973

Comparative evaluation of five serological methods for the diagnosis of sporotrichosis.

The diagnosis of sporotrichosis can be time consuming. Serological procedures could facilitate the rapid and accurate diagnosis of this disease. A slide latex agglutination (SLA) test for sporotrichosis was developed and compared with the tube agglutination (TA), complement fixation (CF), and immunodiffusion (ID) tests in the serological study of 80 proven human cases of sporotrichosis representing the cutaneous, subcutaneous, and extracutaneous forms of the disease. In addition, the indirect fluorescent antibody (IFA) technique was applied to 61 case sera. In the SLA test, latex particles sensitized with culture filtrate antigens from the yeast form of Sporothrix schenckii (B 959) detected 94% of the cases, as compared to 96% of the cases detected by the TA test, 68% by the CF test, and 56% by the ID test. The IFA test detected 90% of the 61 cases. The SLA and ID tests were specific, showing no reactions with sera from 86 persons with no disease or with diseases other than sporotrichosis. Because of its sensitivity, specificity, ease of performance, and ability to provide results in 5 min, the SLA test is highly recommended for routine use in the clinical laboratory.

Agglutination Tests↗
PubMed1973

Specific immunodiffusion test for blastomycosis.

A specific immunodiffusion test for blastomycosis has been developed. The test permitted the detection of approximately 80% of 113 proven cases of blastomycosis. Two diagnostically important precipitins designated A and B were frequently recognized in patients with blastomycosis. Routine use of reference sera containing the A and B precipitins in immunodiffusion tests would permit the specific diagnosis of blastomycosis without the need for parallel tests with coccidioidin and histoplasmin.

Antigens, Fungal↗
PubMed1972

Comparison of a newly developed latex agglutination test and an immunodiffusion test in the diagnosis of systemic candidiasis.

A newly developed latex agglutination (LA) test and a modified immunodiffusion (ID) test were evaluated. The antigen used was a homogenate of Candida albicans. A total of 167 antisera were employed in the evaluation. They included 36 sera from clinically well persons; 78 from patients with various clinical forms of candidiasis; 52 from patients with proven cases of aspergillosis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, nocardiosis, paracoccidioidomycosis, sporotrichosis, and tuberculosis; and one serum from a patient with toruloposis. Use of the LA test in conjunction with the ID test permitted the detection of more than 90% of 43 proven candidiasis cases. Of all the heterologous cases and normal human sera tested, LA reactions were noted with 3 of 10 cryptococcosis case specimens, 1 of 9 tuberculosis case specimens, and with the torulopsemia case serum. In contrast, the only heterologous serum reactive in the ID test was that from the patient with torulopsemia. Torulopsis glabrata and C. albicans antisera gave identical reactions in LA and ID tests with T. glabrata or C. albicans antigens. ID tests with selected antigens, however, permitted differentiation of rabbit and human T. glabrata antibody from that of C. albicans antibody. Six different precipitins were recognized with the C. albicans antigens. The occurrence of multiple precipitin lines and high LA titers was suggestive of severe candidiasis. The LA test, in contrast to the ID test, appeared to have prognostic value. Together, the LA and ID tests provided a simple, rapid, and accurate means of detecting and monitoring infections by species of Candida.

Agglutination Tests↗