Fast-slow wave transitions induced by a random mean flow.

Motivated by recent asymptotic results in atmosphere-ocean fluid dynamics, we present an idealized numerical and theoretical study of two-dimensional dispersive waves propagating through a small-amplitude random mean flow. The objective is to delineate clearly the conditions under which the cumulative Doppler shifting and refraction by the mean flow can change the group velocity of the waves not only in direction, but also in magnitude. The latter effect enables a possible transition from fast to slow waves, which behave very differently. Within our model we find the conditions on the dispersion relation and the mean flow amplitude that allow or rule out such fast-slow transitions. For steady mean flows we determine a finite mean flow amplitude threshold below which such transitions can be ruled out indefinitely. For unsteady mean flows a sufficiently rapid rate of change means that this threshold goes to zero, i.e., in this scenario all waves eventually undergo a fast-slow transition regardless of mean flow amplitude, with corresponding implications for the long-term fate of these waves.

The Yersinia enterocolitica invasin protein promotes major histocompatibility complex class I- and class II-restricted T-cell responses.

Yersinia enterocolitica invasin (Inv) protein confers internalization into and expression of proinflammatory cytokines by host cells. Both events require binding of Inv to beta1 integrins, which initiates signaling cascades including activation of focal adhesion complexes, Rac1, mitogen-activated protein kinase, and NF-kappaB. Here we tested whether Inv might be suitable as a delivery molecule and adjuvant if used as a component of a vaccine. For this purpose, hybrid proteins composed of Inv and ovalbumin (OVA) were prepared, applied as a coating to microparticles, and used for vaccination. Fusion of OVA to Inv did not significantly disturb the ability of Inv to promote host cell binding, internalization, and interleukin-8 (IL-8) secretion when applied as a coating to microparticles. The microparticles were used for vaccination of mice adoptively transferred with OVA-specific T cells from OT-1 or DO11.10 mice. Administration of OVA-Inv-coated microparticles induced OVA-specific T-cell responses. OVA-specific CD4 T cells produced both gamma interferon (IFN-gamma) and IL-4 as determined by enzyme-linked immunosorbent assay. Likewise, pronounced OVA-specific CD8 T-cell responses associated with IFN-gamma production were observed. Together, these results suggest that Inv might be an attractive tool in vaccination as it confers both host cell uptake and adjuvant activity by engagement of beta1 integrins of host cells, which leads to CD4 as well as CD8 T-cell responses.

Sick-building symptoms in office workers in northeastern France: a pilot study.

STUDY OBJECTIVES: To verify that sick building symptoms are present in north-eastern France office workers; to try to identify new confounding factors. METHODS: The design was that of a cross-sectional study with control group. We studied with the same methods the personnel of an air-conditioned building (n=425), and of a naturally ventilated building (n=351). Air temperature and humidity, bacterial and fungal densities were measured by the same technical staff in the two buildings. A standard questionnaire on irritative and respiratory symptoms, personal and family history, and lifestyle was completed by the participants. RESULTS: In univariate analysis, exposure to air-conditioning was associated with an increased prevalence of symptoms (odds ratios-OR-between 1.54 and 2.84). A significant increase in sickness absence was also found among subjects working in air-conditioned offices. As a series of factors were suspected to interfere with these associations, logistic regression was applied. This method confirmed exposure to be an independent determinant of 7 symptoms, and also identified two determinants not previously described: a family history of respiratory diseases and "do-it-yourself' activities. IN CONCLUSION: we found the sick building symptoms to be present in a group of French office workers exposed to air-conditioning. We confirmed the influence of a number of confounding factors and described two further confounders - do-it-yourself activities at home and a history of familial respiratory disease.

Computerized single-breath nitrogen washout: predicted values in a rural French community.

Comparative manual and computer measurements of the alveolar N2 slope and closing volumes have indicated systematic differences. When a computerized system is used in field surveys, predicted values are to be obtained under the same conditions. Therefore, we measured the alveolar nitrogen slope (phase III, PIII), closing volume (CV), and closing capacity (CC) from single-breath N2 washout maneuvers in 158 healthy subjects (68 females), ages 21 to 64 years, from a rural community living in a nonpolluted area of northeast France. PIII, the CV to vital capacity ratio (CV:VC, %), and the CC to the total lung capacity ratio (CC:TLC, %) were regressed against age, height, weight, and the body mass index (BMI, kg/m2) and prediction equations with 95% confidence intervals were computed. PIII increased with age in both sexes and tended to decrease with height in males (r = -0.19, p = .08). The CV:VC and CC:TLC ratios depended on age and, in males, increased with the BMI. Despite accepting a 15% difference between the test VC and the spirometric VC, only 46.3% of asymptomatic nonsmokers produced a valid single-breath nitrogen washout (SBN2) test. This high failure rate limits the usefulness of the test for epidemiologic purposes when older populations "naive" to pulmonary function testing are studied under field-survey conditions.