Apolipoprotein E controls Dectin-1-dependent development of monocyte-derived alveolar macrophages upon pulmonary ß-glucan-induced inflammatory adaptation.

The lung is constantly exposed to the outside world and optimal adaptation of immune responses is crucial for efficient pathogen clearance. However, mechanisms that lead to lung-associated macrophages' functional and developmental adaptation remain elusive. To reveal such mechanisms, we developed a reductionist model of environmental intranasal ß-glucan exposure, allowing for the detailed interrogation of molecular mechanisms of pulmonary macrophage adaptation. Employing single-cell transcriptomics, high-dimensional imaging and flow cytometric characterization paired with in vivo and ex vivo challenge models, we reveal that pulmonary low-grade inflammation results in the development of apolipoprotein E (ApoE)-dependent monocyte-derived alveolar macrophages (ApoE+CD11b+ AMs). ApoE+CD11b+ AMs expressed high levels of CD11b, ApoE, Gpnmb and Ccl6, were glycolytic, highly phagocytic and produced large amounts of interleukin-6 upon restimulation. Functional differences were cell intrinsic, and myeloid cell-specific ApoE ablation inhibited Ly6c+ monocyte to ApoE+CD11b+ AM differentiation dependent on macrophage colony-stimulating factor secretion, promoting ApoE+CD11b+ AM cell death and thus impeding ApoE+CD11b+ AM maintenance. In vivo, ß-glucan-elicited ApoE+CD11b+ AMs limited the bacterial burden of Legionella pneumophilia after infection and improved the disease outcome in vivo and ex vivo in a murine lung fibrosis model. Collectively these data identify ApoE+CD11b+ AMs generated upon environmental cues, under the control of ApoE signaling, as an essential determinant for lung adaptation enhancing tissue resilience.

Selective infrared excitation in D2CO: rotational assignments and the role of collisions.

A time-resolved infrared-ultraviolet double-resonance technique is used to characterize specific rovibrational states pumped by a pulsed CO(2) laser within the nu(4) vibrational ladder of D(2)CO. The roles of rotational and quasiresonant rovibrational relaxation, requiring, respectively, < or =1 and approximately 3 gas-kinetic collisions, are studied. The rotational specificity of the latter suggests that a collision-assisted sequence of infrared absorption steps is able to account for the selective initial stages of multiple-photon excitation in formaldehyde.

Continuously tunable narrow-band operation of an injection-seeded ring-cavity optical parametric oscillator: spectroscopic applications.

A pulsed beta-barium borate optical parametric oscillator is injection seeded by cw diode lasers, yielding continuously tunable narrow-band output at its idler wavelength. A notable feature of this optical parametric oscillator is that it comprises a simple passive ring cavity with no active control of path length as the seed wavelength is scanned. We demonstrate this by recording Doppler-limited photoacoustic absorption spectra of acetylene gas and Doppler-free two-photon fluorescence spectra of rubidium vapor.

Carbon dioxide laser tuning through 110 lines in 3 ms for airborne remote sensing.

Rapid tuning of a 3-m long glow discharge excited CO(2) laser is achieved by a rotating polygonal mirror scanning the intracavity beam across a diffraction grating. The system can tune through 110 different rotational lines spanning wavelengths from 9.2 to 11.1 microm in 3 ms with typical peak powers of 100-500 W at burst repetition rates up to 360 Hz and is suitable for airborne remote sensing. The effects of laser output coupler reflectance, burst rate, scan direction, and current modulation are investigated, and the performance of an optimized system for mineral reflectance measurements is presented. A reflection spectrum of a shale obtained with the rapidly tuned laser at a range of 5 m is shown to compare well to data gathered for the same sample using a slowly tuned cw CO(2) laser.

Rotationally resolved coherent anti-Stokes Raman spectroscopy by using a tunable optical parametric oscillator.

A beta-barium borate optical parametric oscillator (BBO OPO) serves as the tunable source for coherent anti-Stokes Raman spectroscopy (CARS). Two variants of this approach are devised to make rotationally resolved CARS measurements of nitrogen in air. In the scanned CARS technique, the BBO OPO operates in its continuously tuned, narrow-band mode with injection-seeding control of OPO signal wavelength. In the other technique, a free-running BBO OPO is used for single-shot, multiplex CARS measurements.

Bandwidth characteristics of a pulsed optical parametric oscillator: application to degenerate four-wave mixing spectroscopy.

Factors influencing the optical bandwidth of a free-running pulsed beta-barium borate optical parametric oscillator are examined and incorporated in a simple fitting procedure. Spatiospectral phenomena in the optical parametric oscillator output beam are thereby identified; these suggest a novel way to reduce the effective optical bandwidth for spectroscopic purposes. This technique is demonstrated by recording a degenerate fourwave mixing spectrum of sodium atoms in an air-acetylene flame.