Lung Transplantation for People Living With HIV: Promising Mid-term Outcomes.

BACKGROUND: With increasing life expectancy, patients with HIV are more commonly acquiring other chronic diseases, such as end-stage lung disease, for which transplant may be the only effective solution. Until recently, HIV infection was considered a contraindication to lung transplant (LTx). As LTx in people living with HIV (PLWH) becomes more common, there remain limited data on outcomes in this population. METHODS: Using the Organ Procurement and Transplantation Network Standard Transplant Analysis and Research file, we identified LTx recipients with HIV by either serostatus or nucleic acid testing. A control group of confirmed HIV-negative LTx recipients was propensity score matched on age, body mass index, primary diagnosis, and year of transplant. Patient characteristics, transplant parameters, survival, and postoperative outcomes were compared. RESULTS: Fifty-nine LTx recipients with HIV were identified and compared with 236 HIV-negative controls. Among PLWH, cytomegalovirus status was more frequently positive (76.3% versus 58.9%, P = 0.014), and the median Lung Allocation Score at match was higher (44 versus 39, P = 0.004). PLWH were more likely to undergo dialysis postoperatively (18.6% versus 8.9%, P = 0.033), although other complication rates were similar. Fifty-three percent of LTx for PLWH occurred since 2020. One-year survival for PLWH was 91.2% versus 88.6% for controls ( P = 0.620). Three-year survival for a smaller subset was also not statistically significant (HIV versus control: 82.6% versus 77.8%, respectively, P = 0.687). CONCLUSIONS: There was no difference in 1-y survival for LTx recipients living with HIV compared with a matched control group, supporting this group of patients as viable candidates for LTx.

Debye ring diffraction elucidation of 2D photonic crystal self-assembly and ordering at the air-water interface.

We fabricate 2D photonic crystals (2DPC) by spreading a dispersion of charged colloidal particles (diameters = 409, 570, and 915 nm) onto the surface of electrolyte solutions using a needle tip flow method. When the interparticle electrostatic interaction potential is large, particles self-assemble into highly ordered hexagonal close packed (hcp) monolayers. Ordered 2DPC efficiently forward diffract monochromatic light to produce a Debye ring on a screen parallel to the 2DPC. The diameter of the Debye ring is inversely proportional to the 2DPC particle spacing, while the Debye ring brightness and thickness depends on the 2DPC ordering. The Debye ring thickness increases as the 2DPC order decreases. The Debye ring ordering measurements of 2DPC attached to glass slides track measurements of the 2D pair correlation function order parameter calculated from SEM micrographs. The Debye ring method was used to investigate the 2DPC particle spacing, and ordering at the air-solution interface of NaCl solutions, and for 2DPC arrays attached to glass slides. Surprisingly, the 2DPC ordering does not monotonically decrease as the salt concentration increases. This is because of chloride ion adsorption onto the anionic particle surfaces. This adsorption increases the particle surface charge and compensates for the decreased Debye length of the electric double layer when the NaCl concentration is below a critical value.

The Effect of Needle Gauge on the Risk of Pneumothorax and Chest Tube Placement After Percutaneous Computed Tomographic (CT)-Guided Lung Biopsy.

BACKGROUND: The aim of this study was to evaluate the effect of coaxial guide needle gauge (18 vs. 19 gauge) on the risk of pneumothorax and chest tube placement after CT-guided lung biopsy. METHODS: Imaging records of all patients who had undergone CT-guided lung biopsies at our institution from March 1, 2006 to December 9, 2010 were retrospectively reviewed. Univariate and multivariate logistic regression analyses were performed to assess the effect of various patient-, lesion-, and procedure-related variables on subsequent pneumothorax and chest tube placement rates. RESULTS: The study included 4262 biopsies (2304 with 18-gauge and 1958 with 19-gauge coaxial guide needles) in 3917 patients. The rates of pneumothorax and chest tube placement were 30.2 and 15%, respectively. Pneumothorax occurred in 35% of procedures performed with 18-gauge needles and in 24.5% of procedures performed with 19-gauge needles (p < 0.0001). Chest tube insertion occurred in 16.7% of procedures performed with 18-gauge needles and in 13.1% of procedures performed with 19-gauge needles (p = 0.0011). Multivariate logistic regression models demonstrated that the use of an 18-gauge needle was associated with a higher rate of pneumothorax (p < 0.0001) and chest tube placement (p = 0.0003). The following factors were also associated with higher rates of pneumothorax and chest tube placement: older age, emphysema, greater number of pleural surfaces crossed, and a longer biopsy needle path length. CONCLUSIONS: The use of a 19-gauge coaxial guide needle significantly decreases the risk of pneumothorax and chest tube placement compared with an 18-guage needle.

A technique for converting an existing denture into a cast metal-reinforced implant-retained overdenture.

Prosthesis fracture is a common complication associated with implant-retained overdentures. A new overdenture can be strengthened by incorporating a cast metal reinforcement during processing. The authors describe a technique for converting an existing conventional nonreinforced serviceable denture into an overdenture that includes a cast metal reinforcement and its attachments.

Photochemical incorporation of silver quantum dots in monodisperse silica colloids for photonic crystal applications.

We developed a novel method to fabricate nanocomposite monodisperse SiO2 spheres (approximately 100 nm) containing homogeneously dispersed Ag quantum dots (approximately 2 to 5 nm). The inclusion morphology is controlled through the timing of the photochemical reduction of silver ions during hydrolysis of tetraethoxysilane in a microemulsion. Depending on the timing, Ag quantum dots can be directed to different annuli within the SiO2 spheres, as well as onto the SiO2 sphere surfaces. The embedded Ag quantum dots show a plasmon resonance absorption band at 438 nm. These Ag@SiO2 particles have significant surface charge and readily self-assemble into crystalline colloidal array (CCA) photonic crystals which Bragg-diffract light in the visible region. The magnitude of the plasmon resonance absorption depends on the CCA Bragg diffraction condition. The negative dielectric constant of the silver nanoparticles may be decreasing the silica-silver nanodot composite refractive index below that of the water medium. We may be observing an analogue of the Borrmann effect previously observed in X-ray scattering, where the incident and diffracted electric field standing wave becomes localized in regions of small CCA crystal absorption.

UV Raman studies of peptide conformation demonstrate that betanova does not cooperatively unfold.

We used UV resonance Raman spectroscopy (UVRR) excited within the peptide bond pi --> pi* electronic transitions and within the aromatic amino acid pi --> pi* electronic transitions to examine the temperature dependence of the solution conformation of betanova, a 20-residue beta-sheet polypeptide [Kortemme, T., Ramirez-Alvarado, M., and Serrano, L. (1998) Science 281, 253-256]. The 206.5 nm excited UVRR enhances the amide vibrations and demonstrates that betanova has a predominantly beta-sheet structure between 5 and 82 degrees C. The 229 nm excited UVRR, which probes the tyrosine and tryptophan side chain vibrations, shows an increase in the solvent exposure of the tryptophan side chains as the temperature is increased. Our results are consistent with the existence of an intermediate state similar to that calculated by Bursulaya and Brooks [Bursulaya, B. D., and Brooks, C. L. (1999) J. Am. Chem. Soc. 121, 9947-9951] and exclude the previously proposed two-state cooperative folding mechanism. Betanova's structure appears to be molten globule over the 3-82 degrees C temperature range of our study.

Development of an intelligent polymerized crystalline colloidal array colorimetric reagent.

We have developed a novel colorimetric reagent for the determination of Pb2+, pH, and temperature. This colorimetric reagent consists of a dispersion of approximately 100-microm particles composed of an intelligent polymerized crystalline colloidal array (IPCCA). The IPCCA particles are composed of a hydrogel polymerized around a face-centered cubic (fcc) array of monodisperse, highly charged polystyrene colloidal particles. These IPCCA particles diffract visible light because the (111) planes of the fcc polystyrene colloidal particle array have an approximately 200-nm lattice constant. The IPCCA particles also contain a molecular recognition agent that actuates array volume changes as a result of changes in analyte concentration or temperature. This results in changes in the IPCCA lattice constants, which shifts the wavelength of light diffracted. We report here the use of these sensing materials in a liquid dispersion that can be poured into a sample solution. This diffraction measurement method is analogous to X-ray powder diffraction measurements. The diffraction wavelength is monitored at a defined angle relative to the incident light.

Dihedral psi angle dependence of the amide III vibration: a uniquely sensitive UV resonance Raman secondary structural probe.

UV resonance Raman studies of peptide and protein secondary structure demonstrate an extraordinary sensitivity of the amide III (Am III) vibration and the C(alpha)H bending vibration to the amide backbone conformation. We demonstrate that this sensitivity results from a Ramachandran dihedral psi angle dependent coupling of the amide N-H motion to (C)C(alpha)H motion, which results in a psi dependent mixing of the Am III and the (C)C(alpha)H bending motions. The vibrations are intimately mixed at psi approximately 120 degrees, which is associated with both the beta-sheet conformation and random coil conformations. In contrast, these motions are essentially unmixed for the alpha-helix conformation where psi approximately -60 degrees. Theoretical calculations demonstrate a sinusoidal dependence of this mixing on the psi angle and a linear dependence on the distance separating the N-H and (C)C(alpha)H hydrogens. Our results explain the Am III frequency dependence on conformation as well as the resonance Raman enhancement mechanism for the (C)C(alpha)H bending UV Raman band. These results may in the future help us extract amide psi angles from measured UV resonance Raman spectra.

Transient UV Raman spectroscopy finds no crossing barrier between the peptide alpha-helix and fully random coil conformation.

Transient UV resonance Raman measurements excited within the amide pi --> pi transitions of a 21 unit alpha-helical peptide has for the first time determined a lower bound for the unfolding rate of the last alpha-helical turn to form a fully random coil peptide. A 3 ns T-jump is generated with 1.9 microm laser pulses, which are absorbed by water. Subsequent 3 ns 204 nm UV pulses excite the amide Raman spectra at delay times between 3 ns and 1 ms, to monitor the peptide conformational evolution. We find approximately 180 ns relaxation times which result in a rate constant of >5 x 10(6) s(-1) for unfolding of the last alpha-helical turn. Our data are inconsistent with slow alpha-helix nuclei melting.

UV resonance Raman study of angiotensin II conformation in nonaqueous environments: lipid micelles and acetonitrile.

We used 206.5-nm excited resonance Raman measurements to examine the angiotensin II (AII) secondary structure in H(2)O in the presence of dodecylphosphocholine (DPC) micelles, sodium dodecylsulfate (SDS) monomers and micelles, and in a 70% acetonitrile (ACN-d)-30% water solution. Our AII-SDS titration absorption studies indicate the formation of a 1:2 AII:SDS complex in which two negatively charged SDS molecules attach to the AII positively charged N terminus and to Arg(2). Our 206.5-nm excited Raman results indicate that the 1:2 AII:SDS complexation increases the AII beta-turn composition. We also used 228.9-nm Raman excitation to probe the local solvent accessibility of Tyr(4) (AII) in DPC and SDS micelles. Our Tyr (AII) solvent accessibility studies suggest that the Tyr residue is more exposed to the aqueous environment in SDS micelles than in DPC micelles.

Ultraviolet resonance Raman examination of horse apomyoglobin acid unfolding intermediates.

We have used UV resonance Raman spectroscopy to study the acid-induced denaturation of horse apomyoglobin (apoMb) between pH 7. 0 and 1.8. The 206.5 nm excited Raman spectra are dominated by amide vibrations, which are used to quantitatively determine the apoMb secondary structure. The 229 nm excited Raman spectra are dominated by the Tyr and Trp Raman bands, which are analyzed to examine changes of Tyr and Trp environments and solvent exposures. We observe two partially unfolded apoMb intermediates at pH 4 and pH 2, while we observe only one partially unfolded holoMb intermediate at 2, in which the G and H helices are mainly intact, while the rest of protein is unfolded. This partially unfolded holoMb intermediate at pH 2 is essentially identical to the pH 2 apoMb intermediate. The partially unfolded pH 4 apoMb intermediate is composed of the three folded A, G, and H helices and contains 38% helical structure. The changes in the Trp Raman cross sections during the acid-induced denaturation indicates that Trp 7 is likely to be fully exposed in the apoMb pH 4 intermediate and that the A helix melts with a pKa approximately 3.5.

Ultraviolet Raman examination of the environmental dependence of bombolitin I and bombolitin III secondary structure.

Bombolitin I and III (BI and BIII) are small amphiphilic peptides isolated from bumblebee venom. Although they exist in predominately nonhelical conformations in dilute aqueous solutions, we demonstrate, using UV Raman spectroscopy, that they become predominately alpha-helical in solution at pH > 10, in high ionic strength solutions, and in the presence of trifluoroethanol (TFE) and dodecylphosphocholine (DPC) micelles. In this paper, we examine the effects of electrostatic and hydrophobic interactions that control folding of BI and BIII by systematically monitoring their secondary structures as a function of solution conditions. We determine the BI and BIII secondary structure contents by using the quantitative UV Raman methodology of Chi et al. (1998. Biochemistry. 37:2854-2864). Our findings suggest that the alpha-helix turn in BIII at neutral pH is stabilized by a salt bridge between residues Asp2 and Lys5. This initial alpha-helical turn results in different BI and BIII alpha-helical folding mechanisms observed in high pH and high salt concentrations: BIII folds from its single alpha-helix turn close to its N-terminal, whereas the BI alpha-helix probably nucleates within the C-terminal half. We also used quasielastic light scattering to demonstrate that the BI and BIII alpha-helix formation in 0.2 M Ca(ClO4)2 is accompanied by formation of trimers and hexamers, respectively.

Children's goals and strategies in response to conflicts within a friendship.

Little is known about the skills required for friendship, as distinct from those required for peer acceptance. The present study examined whether children's goals and strategies in friendship conflict situations are predictive of their friendship adjustment, after accounting for level of peer acceptance. Fourth- and 5th-grade children (N = 696) responded to 30 hypothetical situations in which they were having a conflict with a friend. Results indicated that children's goals were highly related to their strategies and that children's goals and strategies were predictive of their real-life friendship adjustment. Pursuing the goal of revenge toward a friend was the goal or strategy most strongly associated with lacking friends and having poor-quality friendships. Gender differences were also found for each goal and strategy, with girls displaying a more prosocial goal and strategy orientation than boys.

Entropic trapping of macromolecules by mesoscopic periodic voids in a polymer hydrogel.

The separation of macromolecules such as polymers and DNA by means of electrophoresis, gel permeation chromatography or filtration exploits size-dependent differences in the time it takes for the molecules to migrate through a random porous network. Transport through the gel matrices, which usually consist of full swollen crosslinked polymers, depends on the relative size of the macromolecule compared with the pore radius. Sufficiently small molecules are thought to adopt an approximately spherical conformation when diffusing through the gel matrix, whereas larger ones are forced to migrate in a snake-like fashion. Molecules of intermediate size, however, can get temporarily trapped in the largest pores of the matrix, where the molecule can extend and thus maximize its conformational entropy. This 'entropic trapping' is thought to increase the dependence of diffusion rate on molecular size. Here we report the direct experimental verification of this phenomenon. Bragg diffraction from a hydrogel containing a periodic array of monodisperse water voids confirms that polymers of different weights partition between the hydrogel matrix and the water voids according to the predictions of the entropic trapping theory. Our approach might also lead to the design of improved separation media based on entropic trapping.

UV resonance Raman-selective amide vibrational enhancement: quantitative methodology for determining protein secondary structure.

We have directly determined the amide band resonance Raman spectra of the "average" pure alpha-helix, beta-sheet, and unordered secondary structures by exciting within the amide pi-->pi* transitions at 206.5 nm. The Raman spectra are dominated by the amide bands of the peptide backbone. We have empirically determined the average pure alpha-helix, beta-sheet, and unordered resonance Raman spectra from the amide resonance Raman spectra of 13 proteins with well-known X-ray crystal structures. We demonstrate that we can simultaneously utilize the amide I, II, and III bands and the Calpha-H amide bending vibrations of these average secondary structure spectra to directly determine protein secondary structure. The UV Raman method appears to be complementary, and in some cases superior, to the existing methods, such as CD, VCD, and absorption spectroscopy. In addition, the spectra are immune to the light-scattering artifacts that plague CD, VCD, and IR absorption measurements. Thus, it will be possible to examine proteins in micelles and other scattering media.

UV resonance Raman determination of protein acid denaturation: selective unfolding of helical segments of horse myoglobin.

We have used UV resonance Raman spectroscopy to study the acid denaturation of horse heart aquometmyoglobin (Mb) between pH 7.5 and 1.5. Raman spectra excited at 206.5 nm are dominated by amide vibrations, which are analyzed by using a new methodology to quantitatively determine the Mb secondary structure. In contrast, the 229-nm Raman spectra are dominated by the Tyr and Trp Raman bands, which are analyzed to examine changes in Tyr and Trp environments, such as exposure to water, hydrogen bonding, and, for Trp, any alterations of the dihedral angle between the Trp ring and its linkage to the protein backbone. We uniquely determined which Mb alpha-helices melt by combining the amide, Tyr, and Trp Raman spectral information with heme absorption spectral information. We calculate that the Mb alpha-helical composition decreases from approximately 80% at neutral pH to approximately 19% below pH 3.5. The Trp Raman cross sections dramatically decrease at low pH to values which indicate that they are fully exposed to water; this result indicates that the A helix melts. The Tyr Raman bands are pH independent, which indicates that the G and H helices around the Tyr residues do not melt. The dramatic heme absorption acid denaturation changes indicate major alterations of the heme pocket and changes in heme binding. These results indicate that the A, B, C, D, E, and F helices melt in a concerted fashion, while the antiparallel G and H helices only partially melt.

Polymerized colloidal crystal hydrogel films as intelligent chemical sensing materials.

Chemical sensors respond to the presence of a specific analyte in a variety of ways. One of the most convenient is a change in optical properties, and in particular a visually perceptible colour change. Here we report the preparation of a material that changes colour in response to a chemical signal by means of a change in diffraction (rather than absorption) properties. Our material is a crystalline colloidal array of polymer spheres (roughly 100 nm diameter) polymerized within a hydrogel that swells and shrinks reversibly in the presence of certain analytes (here metal ions and glucose). The crystalline colloidal array diffracts light at (visible) wavelengths determined by the lattice spacing, which gives rise to an intense colour. The hydrogel contains either a molecular-recognition group that binds the analyte selectively (crown ethers for metal ions), or a molecular-recognition agent that reacts with the analyte selectively. These recognition events cause the gel to swell owing to an increased osmotic pressure, which increases the mean separation between the colloidal spheres and so shifts the Bragg peak of the diffracted light to longer wavelengths. We anticipate that this strategy can be used to prepare 'intelligent' materials responsive to a wide range of analytes, including viruses.

Topical tetracaine attenuates the pain of infiltration of buffered lidocaine.

OBJECTIVE: To determine whether topical tetracaine attenuates the pain of buffered lidocaine infiltration. METHODS: A prospective, randomized, double-blind trial was conducted involving adults with lacerations being repaired following local anesthesia. Two 0.5-mL injections of buffered lidocaine were given in a standardized manner. Injection 1 was given prior to application of topical study solution. Injection 2 was given on the opposite side of the laceration after topical application of a study solution that was 4 mL of either tetracaine or normal saline. Pain of each infiltration was measured using a visual analog pain scale. Pain score differences (injection 1 - injection 2) were compared for the 2 study solutions using a Wilcoxon 2-sample signed-rank test. RESULTS: Of 57 subjects studied, 29 received tetracaine and 28 received saline. The groups were similar in age, gender, wound length, wound location, and initial pain score. Pain scores decreased significantly in the tetracaine group as compared with the saline group. The median pain score difference for tetracaine was 12.0 mm, with an interquartile range (IQR) of 2 to 43 mm, as compared with 2 mm, with an IQR of - 17 to 21 mm for saline (p = 0.048). CONCLUSION: Topical tetracaine attenuates the pain of infiltration of buffered lidocaine.