Bronchoalveolar lavage fluid lymphocytosis in chronic hypersensitivity pneumonitis: a systematic review and meta-analysis

Background

The role of bronchoalveolar lavage fluid (BALF) lymphocyte percentage in diagnosing chronic hypersensitivity pneumonitis (CHP) is unclear. We conducted a systematic review and meta-analysis of bronchoalveolar lavage (BAL) lymphocyte percentage in the diagnosis of CHP.

Methods

We searched Medline, Embase and the Cochrane Library from inception to August 2019. Individual patient data were obtained to test performance characteristics of BAL lymphocyte percentage at different thresholds. Random-effects models were used for pooled estimates, with comparisons made between CHP and non-CHP interstitial lung diseases (ILDs).

Results

Fifty-three studies were included in the systematic review and 42 in the meta-analysis. The pooled estimate for BAL lymphocyte percentage was 42.8% (95% CI 37.7–47.8, I2=95.3%) in CHP, 10.0% (95% CI 6.9–13.1, I2=91.2%) in idiopathic pulmonary fibrosis (IPF), 23.1% (95% CI 3.0–43.2, I2=85.2%) in non-IPF idiopathic interstitial pneumonia (IIP), 23.4% (95% CI 11.0–35.9, I2=45.7%) in connective-tissue disease associated ILD (CTD-ILD) and 31.2% (95% CI 17.6–44.8, I2=95.2%) in sarcoidosis. Results differed between CHP and IPF (p<0.0001), non-IPF IIP (p=0.0309) or CTD-ILD (p=0.0824), but not between CHP and sarcoidosis (p=0.0966). Using individual patient data from eight studies, a lymphocyte percentage threshold of >20% provided a sensitivity of 68.1% and a specificity of 64.8% for CHP. Higher thresholds provided lower sensitivity with higher specificity. Older age and ever having smoked were associated with lower lymphocyte percentage in CHP.

Conclusions

BAL lymphocyte percentage is higher in CHP compared to IPF and other IIPs, with higher thresholds providing improved specificity at the cost of sensitivity. However, the parent studies are at risk of incorporation bias and prospective studies should evaluate the additive discriminate value of BAL lymphocyte percentage to accurately diagnose CHP.

3D Strain in 2D Materials: To What Extent is Monolayer Graphene Graphite?

This work addresses a fundamental question: To what extent is graphene graphite? In particular does 2D graphene have many of the same 3D mechanical properties as graphite, such as the bulk modulus and elastic constant c_{33}? We have obtained, for the first time, unambiguous Raman spectra from unsupported monolayer graphene under pressure. We have used these data to quantify the out-of-plane stiffness of monolayer graphene, which is hard to define due to its 2D nature. Our data indicate a first physically meaningful out-of-plane stiffness of monolayer graphene, and find it to be consistent with that of graphite. We also report a shift rate of the in-plane phonon frequency of unsupported monolayer graphene to be 5.4  cm^{-1} GPa^{-1}, very close to that of graphite (4.7  cm^{-1} GPa^{-1}), contrary to the previous value for supported graphene. Our results imply that monolayer graphene has similar in-plane and out-of-plane stiffnesses, and anharmonicities to graphite.

Resonant photoluminescence studies of carrier localisation in c-plane InGaN/GaN quantum well structures

In this paper we report on changes in the form of the low temperature (12 K) photoluminescence spectra of an InGaN/GaN quantum well structure as a function of excitation photon energy. As the photon energy is progressively reduced we observe at a critical energy a change in the form of the spectra from one which is determined by the occupation of the complete distribution of hole localisation centres to one which is determined by the resonant excitation of specific localisation sites. This change is governed by an effective mobility edge whereby the photo-excited holes remain localised at their initial energy and are prevented from scattering to other localisation sites. This assignment is confirmed by the results of atomistic tight binding calculations which show that the wave function overlap of the lowest lying localised holes with other hole states is low compared with the overlap of higher lying hole states with other higher lying hole states.

High-quality III-nitride films on conductive, transparent (2̅01)-oriented β-Ga2O3 using a GaN buffer layer

We demonstrate the high structural and optical properties of InxGa1-xN epilayers (0 ≤ x ≤ 23) grown on conductive and transparent (01)-oriented β-Ga2O3 substrates using a low-temperature GaN buffer layer rather than AlN buffer layer, which enhances the quality and stability of the crystals compared to those grown on (100)-oriented β-Ga2O3. Raman maps show that the 2″ wafer is relaxed and uniform. Transmission electron microscopy (TEM) reveals that the dislocation density reduces considerably (~4.8 × 10(7) cm(-2)) at the grain centers. High-resolution TEM analysis demonstrates that most dislocations emerge at an angle with respect to the c-axis, whereas dislocations of the opposite phase form a loop and annihilate each other. The dislocation behavior is due to irregular (01) β-Ga2O3 surface at the interface and distorted buffer layer, followed by relaxed GaN epilayer. Photoluminescence results confirm high optical quality and time-resolved spectroscopy shows that the recombination is governed by bound excitons. We find that a low root-mean-square average (≤1.5 nm) of InxGa1-xN epilayers can be achieved with high optical quality of InxGa1-xN epilayers. We reveal that (01)-oriented β-Ga2O3 substrate has a strong potential for use in large-scale high-quality vertical light emitting device design.

Heterogeneous integration of gallium nitride light-emitting diodes on diamond and silica by transfer printing

We report the transfer printing of blue-emitting micron-scale light-emitting diodes (micro-LEDs) onto fused silica and diamond substrates without the use of intermediary adhesion layers. A consistent Van der Waals bond was achieved via liquid capillary action, despite curvature of the LED membranes following release from their native silicon growth substrates. The excellence of diamond as a heat-spreader allowed the printed membrane LEDs to achieve optical power output density of 10 W/cm(2) when operated at a current density of 254 A/cm(2). This high-current-density operation enabled optical data transmission from the LEDs at 400 Mbit/s.

Direct observation of depth-dependent atomic displacements associated with dislocations in gallium nitride

We demonstrate that the aberration-corrected scanning transmission electron microscope has a sufficiently small depth of field to observe depth-dependent atomic displacements in a crystal. The depth-dependent displacements associated with the Eshelby twist of dislocations in GaN normal to the foil with a screw component of the Burgers vector are directly imaged. We show that these displacements are observed as a rotation of the lattice between images taken in a focal series. From the sense of the rotation, the sign of the screw component can be determined.

Prospects of III-nitride optoelectronics grown on Si

The use of III-nitride-based light-emitting diodes (LEDs) is now widespread in applications such as indicator lamps, display panels, backlighting for liquid-crystal display TVs and computer screens, traffic lights, etc. To meet the huge market demand and lower the manufacturing cost, the LED industry is moving fast from 2 inch to 4 inch and recently to 6 inch wafer sizes. Although Al2O3 (sapphire) and SiC remain the dominant substrate materials for the epitaxy of nitride LEDs, the use of large Si substrates attracts great interest because Si wafers are readily available in large diameters at low cost. In addition, such wafers are compatible with existing processing lines for 6 inch and larger wafers commonly used in the electronics industry. During the last decade, much exciting progress has been achieved in improving the performance of GaN-on-Si devices. In this contribution, the status and prospects of III-nitride optoelectronics grown on Si substrates are reviewed. The issues involved in the growth of GaN-based LED structures on Si and possible solutions are outlined, together with a brief introduction to some novel in situ and ex situ monitoring/characterization tools, which are especially useful for the growth of GaN-on-Si structures.

Mg doping affects dislocation core structures in GaN

Aberration-corrected scanning transmission electron microscopy was used to investigate the core structures of threading dislocations in undoped GaN films with both high and low dislocation densities, and in a comparable high dislocation density Mg-doped GaN film. All a-type dislocations in all samples have a 5/7-atom core structure. In contrast, most (a+c)-type dislocations in undoped GaN dissociate due to local strain variations from nearby dislocations. In contrast, Mg doping prevents (a+c)-type dislocation dissociation. Our data indicate that Mg affects dislocation cores in GaN significantly.

Imaging dislocations in gallium nitride across broad areas using atomic force microscopy

We have employed an atomic force microscope with a high sampling rate to image GaN samples grown using an epitaxial layer overgrowth technique and treated with silane and ammonia to enlarge the surface pits associated with threading dislocations (TDs). This allows TDs to be identified in high pixel density images tens of microns in size providing detailed information about the spatial distribution of the TDs. An automated software tool has been developed, which identifies the coordinates of the TDs in the image. Additionally, we have imaged the same sample using Kelvin probe force microscopy, again at high pixel density, providing data about the local changes in surface potential associated with hundreds of dislocations.

Quantitative secondary electron energy filtering in a scanning electron microscope and its applications

Two-dimensional dopant mapping in the scanning electron microscope (SEM) has recently attracted attention due to its ability to measure dopant levels rapidly with high spatial resolution while requiring little or no sample preparation. The dopant concentration could be derived from the energy distribution of secondary electrons emitted per doped region. However, the lack of reliable quantification, when standard SEM imaging is used, has so far hindered a wide application of the technique. This paper aims to resolve this problem with quantitative energy-filtering using a through-the-lens (TTL) detector in a field emission gun SEM (FEG-SEM). We have used the linear shift obtained in the SE energy distribution with variable specimen bias using sample containing copper wires, defined as the experimental detector response R(exp), to quantify the energy filtering. Using different experimental conditions, values of (2.42+/-0.04)<or=R(exp)<or=(3.01+/-0.05) were obtained. Results were validated by comparison with calculations obtained from ray-tracing simulations. Recommendations for the linear range of the TTL detector as an energy filter were established on the basis of these results. In addition, using our quantitative energy-filtering capabilities, the potential difference across a Si pn-junction was measured to be 0.81+/-0.10 V, which is in good agreement with the calculated value.

Electrophoretic manipulation of single DNA molecules in nanofabricated capillaries

We demonstrate the use of nanofabricated capillaries, integrated as part of a microfluidic structure, to study the electrophoretic behaviour of single, fluorescently-labelled, molecules of DNA as a function of capillary size. The nanocapillaries, fabricated using a focused ion beam, have cross-sections down to 150 x 180 nm. Control of single-molecule direction and velocity was achieved using voltage manipulation. DNA mobility was found to increase with decreasing cross-section, which we interpret in terms of reduced electro-osmotic counter-flow. Such nanofabricated capillaries as part of larger fluidic structures have great potential for biotechnology, particularly single molecule manipulation and analysis.

Electron energy-loss near edge structure (ELNES) of InGaN quantum wells

Lasers and light-emitting diodes (LEDs) that emit in the blue to green region are often based on InxGa1-xN quantum well structures. Ionization edges in the electron energy-loss spectrum contain fine structures (called the energy-loss near edge structure (ELNES)) and provide information about the electronic structure. In this paper we compare the experimental and calculated ELNES for the N-K ionization edge of InxGa1-xN quantum wells. When the effects of the core-hole are included in the calculations, agreement between experimental and calculated spectra is very good. Strain has been shown to accentuate the effects of In on the ELNES and moves the ionization edge onset down in energy, relative to the other features. These results suggest that ELNES may provide an alternative method to lattice imaging to determine the presence of strain in this system.

Analysis of contacts and V-defects in GaN device structures by transmission electron microscopy

This paper describes the microstructure of ohmic contacts to an AlGaN/GaN heterostructure, of interest for high power transistors, and an analysis of V-defects in an InGaN/GaN multi-quantum well (MQW) light-emitting structure. A combination of different transmission electron microscopy (TEM) techniques has been employed, as they provide complementary information. These include bright field and dark field TEM, high-resolution electron microscopy, X-ray mapping, energy filtered TEM and high angle annular dark field. A full determination of the phase distribution in the ohmic contacts was achieved. The onset of low contact resistance was found to correspond with the formation of an interfacial layer containing both TiN and AlN, and of an intermetallic layer containing Al, Ti and Au in contact with it. The MQW structures were capped with a p-type GaN layer, and TEM and ADF studies of the samples show a number of V-defects 100-200 nm apart along the MQW. Each V-defect incorporates a pure edge (b = 1/3 <11-20>) dislocation, which runs through its apex up to the free surface. The defects contain GaN with no InGaN layers, suggesting the V-pits have been filled in by the capping layer.

Energy-filtered transmission electron microscopy of multilayers in semiconductors

Quantitative analysis of novel semiconductors with wide or ultrathin multilayers of atomic dimensions is very important in order to control electronic and optical properties, but rather difficult due to the limited resolution in most techniques. In this paper we attempt to assess how effectively the total As dopant concentration in ultrathin As doped layers in InP and the Ti atomic fraction in a TixAl1-xN multilayer can be analysed quantitatively using energy-filtered imaging. These two materials have characteristic edges located at widely different energy losses, with the L edge of As being above 1000 eV, while that of Ti is around 450 eV. We have quantified the As concentration using the three-window technique and theoretical cross-sections and we find that the resolution limit is dominated by the signal-to-noise ratio in this delta-doped specimen. However, the accuracy of the Ti atomic fraction in TixAl1-xN can be as good as 10 at% for specimens of uniform thickness made by focused ion beam milling. We will compare our results with measurements of the composition made using Fresnel contrast, high resolution imaging and high angle annular dark field techniques.

Quantitative analysis of ultrathin doping layers in semiconductors using high-angle annular dark field images

It is well known that the high-angle annular dark field (HAADF) technique in scanning transmission electron microscopy is an incoherent imaging process in the lateral (xy) plane. However, as a consequence of the existence of partial coherence in the z direction, accurate quantitative interpretation of image intensity is difficult. The effects of coherence in the z direction can be reduced by increasing the inner collector angle of the annular detector so that the scattering from atoms in the z direction is essentially incoherent. We thus show that it is feasible to quantify the total As concentration of ultrathin InAsxP1-x layers in InP in a simple but accurate way using a thickness integrated Bloch wave calculation including phonon scattering with a large inner collector angle of the annular detector of around 150 mrad. We compare the As composition derived from this approach with that from the Fresnel method and high resolution imaging. We also show that the non-linear variation of the HAADF intensity with thickness is consistent with our simpler simulations for such conditions. Therefore, this approach enables us easily and quickly to quantify compositions using HAADF images. The tetragonal distortion due to lattice mismatch is also shown to influence the contrast and has been included in the calculations.

Ligand binding to the serotonin transporter: equilibria, kinetics, and ion dependence

The effects of Na+ and Cl- on the binding of [3H]imipramine and the cocaine analog [125I]-beta-carbomethoxy-3 beta-(4-iodophenyl)tropane([125I]-beta-CIT) to the human platelet serotonin transporter have been measured. The ion dependence of beta-CIT binding is consistent with binding beta-CIT together with one Na+ ion, but not in an ordered sequence. Imipramine affinity, like beta-CIT affinity, is increased by Na+, but imipramine binding involves at least two Na+ ions. This conclusion is based on the observation that both imipramine association rate constants and equilibrium affinity constants show a sigmoidal Na+ dependence. As with beta-CIT, the imipramine and Na+ binding sequence is not strictly ordered. Cl- increases imipramine affinity, apparently by slowing dissociation. beta-CIT binding occurs even in the absence of Na+ and Cl-. This provided a means to measure substrate and inhibitor affinity in both the presence and absence of cotransported ions. Nontransported inhibitors, such as imipramine and citalopram, as well as the transport substrates serotonin and 3,4-(methylenedioxy)methamphetamine all displaced beta-CIT binding in the absence of NaCl. In the absence of Cl-, Na+ increased the affinity of nontransported inhibitors but not of substrates. The results suggest that Na+ and Cl- induce independent changes in the transporter binding site and that binding of substrates and inhibitors is affected differently by these changes.

Substrate and inhibitor binding and translocation by the platelet plasma membrane serotonin transporter

The Na+ and Cl- dependence of imipramine binding and dissociation were determined in platelet plasma membrane vesicles. Equilibrium imipramine binding affinity depends on Na+ binding to two non-interacting, low-affinity sites. Binding of a single Cl- ion also enhances imipramine affinity. Imipramine dissociation is inhibited by Na+ and Cl-, indicating that both ions can bind after imipramine. Of the two Na+ ions required for imipramine binding, only one is involved in slowing imipramine dissociation, indicating that imipramine binding makes the two Na+ ions non-equivalent. The initial rate of imipramine association is strongly Na(+)-dependent, suggesting that Na+ binds prior to imipramine. Cl-, however, affects imipramine dissociation but not association. Thus, while Na+ and Cl- can bind either before or after imipramine, kinetic considerations impose a most likely binding order of first Na+, then imipramine and finally Cl-. We have confirmed and extended these conclusions using serotonin exchange and efflux measurements. Efflux of radioactivity from vesicles preloaded with [3H]serotonin is stimulated by both external K+ and external unlabelled serotonin. K+ acts to accelerate a step that is rate-limiting for net efflux but that does not involve Na+, Cl- or serotonin translocation. Unlabelled serotonin accelerates radioactivity efflux by exchanging with intravesicular label. This serotonin exchange requires external Cl-, but not external Na+. These results suggest that first Na+, then serotonin and finally Cl- bind from the external medium. Although serotonin exchange requires external Cl-, internal Cl- is not required. These results suggest that translocation does not disturb the spatial order of bound substrates, which dissociate internally in a first-in-first-out order.

2-Iodoimipramine, a novel ligand for the serotonin transporter

Iodoimipramine was synthesized by iodinating imipramine with ICI. Iodoimipramine competitively inhibits [3H]imipramine binding with a KI of 0.52 nM and also inhibits [3H]serotonin transport competitively, suggesting that serotonin, imipramine, and iodoimipramine all bind to the same site on the serotonin transporter. Association of [125I]iodoimipramine to platelet membranes in Na+ requires 20 min to reach equilibrium at 25 degrees and 1.5 hr at 0 degrees. [125I] Iodoimipramine binding at equilibrium is saturable and Na+ dependent, with a KD of 0.58 nM and a Bmax of 1.3 pmol/mg at 25 degrees. Serotonin competitively inhibits [125I]iodoimipramine binding, with a KI of 1.3 microM. [125I]Iodoimipramine bound at 0 degrees in the presence of Na+ does not dissociate unless the temperature is raised or Na+ is removed from the medium. At 25 degrees, dissociation of [125I] iodoimipramine from platelet membranes in the presence of Na+ is only partial, with 40% of the ligand remaining persistently bound over 5 hr after a 50-fold dilution.

Morphology and physiological properties of interneurons in the olfactory midbrain of the crayfish

1. Intracellular recording and staining was used to characterize neurons in the crayfish (Procambarus clarkii) brain that respond to chemical stimuli applied to the major olfactory organs, the antennules. 2. Two distinct morphological types of neurons that have major projections in the olfactory lobes (OLs) of the brain were characterized anatomically (Figs. 1, 2, 3; Table 2) and physiologically (Figs. 4, 5, 6; Table 3). 3. Different individual neurons of one type, with similar 'tree-like' projections in the OLs, have somata distributed in at least 5 different cell body clusters of the brain (Fig. 3) and link different subsets of neuropilar lobes through their distributed arbors (Fig. 1, Table 2). 4. Excitatory, inhibitory and mixed responses were recorded in different neurons when odorant mixtures or individual components of these mixtures were applied to the antennules. Response spectra to individual components were broad and overlapping, but not identical in the neurons tested (Fig. 4; Table 3). Mixture interactions appear to be additive in most of the neurons that we tested, but evidence was obtained for mixture suppression in several cases (Fig. 6). 5. Most of the neurons recorded in this study responded only to stimulation of the ipsilateral antennule (Fig. 5), although subthreshold activity to stimuli applied contralaterally was recorded in several neurons that were strongly excited by ipsilateral stimuli. 6. Chemoresponsive neurons without projections in OL's that have all of their branches confined to the brain, or that project an axon in the circumesophageal connective, are described (Fig. 7).

Antidepressant binding to the porcine and human platelet serotonin transporters

The ability of four antidepressant drugs, imipramine, alaproclate, norzimelidine, and fluvoxamine, to inhibit serotonin transport into platelet plasma membrane vesicles was tested over a range of external Na+ concentrations. Imipramine affinity, as we previously reported [J. Biol. Chem. 258:6115-6119 (1983)] increases sigmoidally with Na+. When measured by inhibition of serotonin transport, the affinity for alaproclate and norzimelidine is much less sensitive to Na+ and fluvoxamine actually inhibits more avidly at lower Na+. All of the drugs competitively inhibit serotonin transport. Moreover, alaproclate, norzimelidine, and fluvoxamine all competitively displace [3H]imipramine from platelet plasma membranes. The Ki for fluvoxamine inhibition of transport is 16-fold higher than its Ki for inhibition of imipramine binding. In contrast, alaproclate inhibits transport at concentrations lower than those required to block imipramine binding. In the case of fluvoxamine, and possibly also alaproclate, these differences are not due to separate sites mediating substrate and imipramine binding but rather to differences in the nature of binding and transport measurements. The results suggest that these antidepressant drugs and serotonin all bind to the same site, or to overlapping sites on the serotonin transporter, or to sites on the transporter whose occupation is mutually exclusive with substrate site occupation. The observation that binding of each ligand reacts differently to changes in Na+ suggests that distinct subsites are involved in each case. As reported previously by Wennogle and Myerson [Eur. J. Pharmacol. 86:303-307 (1983)] serotonin decreases the rate of imipramine dissociation from human platelet membranes. This effect is not observed in porcine platelets, is not Na+ dependent, and requires serotonin concentrations over 100 times the Km for transport. It is likely, therefore, to result from serotonin binding to a site distinct from the transport active site.

Lack of metabolism as the biochemical basis of bleomycin-induced pulmonary toxicity

The biochemical basis for bleomycin-induced pulmonary toxicity was studied in vitro and in vivo with an improved HPLC system. The in vitro metabolism of bleomycin A2 to desamido-bleomycin A2 was measured in tissue homogenates from a species sensitive (mice) and relatively resistant (rabbits) to the pulmonary fibrogenic properties of bleomycin. Lung tissue from mice lacked detectable bleomycin hydrolase activity, whereas rabbit lung tissue homogenates had high levels of the enzyme activity, equaling that seen in rabbit kidneys and spleen. Injection of radiolabeled bleomycin A2 into mice demonstrated that only a small percentage of the total dose was taken up by any organ and that extensive metabolism of this drug occurred within 1 hr in liver, kidneys, and spleen but not in lungs in vivo. In addition, metabolites other than desamido-bleomycin A2 were prominent, and their relative amounts increased with time. Mice injected subcutaneously with bleomycin A2 developed pulmonary fibrosis, while animals treated with equivalent doses of desamido-bleomycin A2 did not, indicating that this metabolite is not as toxic to the lungs as is the parent compound. These results provide direct evidence that metabolism plays a major role in determining the toxic potential of bleomycin to the lungs.