Controllable structural and optical properties of NaYF4:Tm, Yb microparticles by Yb3+ doping for anti-counterfeiting.

Hexagonal NaYF4:Tm, Yb upconversion (UC) phosphors with excellent UC luminescence quantum efficiency and chemical stability meet demands for applications in bioimaging and anti-counterfeiting printing. In this work, a series of NaYF4:Tm, Yb upconversion microparticles (UCMPs) with different concentrations of Yb were synthesized by a hydrothermal method. Then, the UCMPs become hydrophilic through surface oxidation of the oleic acid (C-18) ligand to azelaic acid (C-9) using the Lemieux-von Rodloff reagent. The structure and morphology of UCMPs were investigated by X-ray diffraction and scanning electron microscopy. The optical properties were studied using diffusion reflectance spectroscopy and photoluminescent spectroscopy under 980 nm laser irradiation. The emission peaks of the Tm3+ ions are 450, 474, 650, 690, and 800 nm, attributed to the transitions from the excited state to ground state 3H6. These emissions are the results of two or three photon absorption through multi-step resonance energy transfer from excited Yb3+, confirmed via a power-dependent luminescence study. The results show that the crystal phases and luminescence properties of the NaYF4:Tm, Yb UCMPs are controlled by changing the Yb doping concentration. The printed patterns are readable under the excitation of a 980 nm LED. Moreover, the zeta potential analysis shows that the UCMPs after surface oxidation are water dispersible. In particular, the naked eye can observe the enormous upconversion emissions in UCMPs. These findings indicated that this fluorescent material is an ideal candidate for anti-counterfeiting and biological applications.

Optimum fabrication parameters for preparing high performance SERS substrates based on Si pyramid structure and silver nanoparticles.

In this work, we propose simple and inexpensive methods to prepare micro/nano hierarchical Surface-Enhanced Raman Scattering (SERS) substrates, in which pyramid structure is created by using anisotropic wet etching of a silicon wafer and a silver thin film is deposited on these pyramid arrays by thermal evaporation. The ensemble is then annealed at 450 °C for 2 hours to form silver nanoparticles (AgNPs). The sizes and density of the pyramids and AgNPs are optimized mainly by changing the etching temperature (60-80 °C), the thickness of the Ag-film (15-45 nm) and etching time (3-10 min). The ultraviolet visible (UV-Vis) absorbance spectra show that the AgNPs formed with the 30 nm-thick film exhibit the strongest plasmonic effect. Under these conditions, the spherical AgNPs with sizes of 42-48 nm are densely distributed on the silicon micro-pyramid array. The obtained SERS signal is the strongest at the pyramid base-edge size of 7-10 µm. The enhancement factor obtained from the abamectin probe molecules is as high as 1 × 106 and the SERS substrates enable the detection of abamectin concentrations as low as 5.7 × 10-9 M. Therefore, this work provides a novel SERS substrate structure that has a high potential for use in medicine and biotechnology or as a food security sensor.

Sputum is a surrogate for bronchoalveolar lavage for monitoring Mycobacterium tuberculosis transcriptional profiles in TB patients.

Pathogen-targeted transcriptional profiling in human sputum may elucidate the physiologic state of Mycobacterium tuberculosis (M. tuberculosis) during infection and treatment. However, whether M. tuberculosis transcription in sputum recapitulates transcription in the lung is uncertain. We therefore compared M. tuberculosis transcription in human sputum and bronchoalveolar lavage (BAL) samples from 11 HIV-negative South African patients with pulmonary tuberculosis. We additionally compared these clinical samples with in vitro log phase aerobic growth and hypoxic non-replicating persistence (NRP-2). Of 2179 M. tuberculosis transcripts assayed in sputum and BAL via multiplex RT-PCR, 194 (8.9%) had a p-value <0.05, but none were significant after correction for multiple testing. Categorical enrichment analysis indicated that expression of the hypoxia-responsive DosR regulon was higher in BAL than in sputum. M. tuberculosis transcription in BAL and sputum was distinct from both aerobic growth and NRP-2, with a range of 396-1020 transcripts significantly differentially expressed after multiple testing correction. Collectively, our results indicate that M. tuberculosis transcription in sputum approximates M. tuberculosis transcription in the lung. Minor differences between M. tuberculosis transcription in BAL and sputum suggested lower oxygen concentrations or higher nitric oxide concentrations in BAL. M. tuberculosis-targeted transcriptional profiling of sputa may be a powerful tool for understanding M. tuberculosis pathogenesis and monitoring treatment responses in vivo.

Adaptation of Mycobacterium tuberculosis to Impaired Host Immunity in HIV-Infected Patients.

BACKGROUND: It is unknown whether immunosuppression influences the physiologic state of Mycobacterium tuberculosis in vivo. We evaluated the impact of host immunity by comparing M. tuberculosis and human gene transcription in sputum between human immunodeficiency virus (HIV)-infected and uninfected patients with tuberculosis. METHODS: We collected sputum specimens before treatment from Gambians and Ugandans with pulmonary tuberculosis, revealed by positive results of acid-fast bacillus smears. We quantified expression of 2179 M. tuberculosis genes and 234 human immune genes via quantitative reverse transcription-polymerase chain reaction. We summarized genes from key functional categories with significantly increased or decreased expression. RESULTS: A total of 24 of 65 patients with tuberculosis were HIV infected. M. tuberculosis DosR regulon genes were less highly expressed among HIV-infected patients with tuberculosis than among HIV-uninfected patients with tuberculosis (Gambia, P < .0001; Uganda, P = .037). In profiling of human genes from the same sputa, HIV-infected patients had 3.4-fold lower expression of IFNG (P = .005), 4.9-fold higher expression of ARG1 (P = .0006), and 3.4-fold higher expression of IL10 (P = .0002) than in HIV-uninfected patients with tuberculosis. CONCLUSIONS: M. tuberculosis in HIV-infected patients had lower expression of the DosR regulon, a critical metabolic and immunomodulatory switch induced by NO, carbon monoxide, and hypoxia. Our human data suggest that decreased DosR expression may result from alternative pathway activation of macrophages, with consequent decreased NO expression and/or by poor granuloma formation with consequent decreased hypoxic stress.

Transcriptional Adaptation of Drug-tolerant Mycobacterium tuberculosis During Treatment of Human Tuberculosis.

BACKGROUND: Treatment initiation rapidly kills most drug-susceptible Mycobacterium tuberculosis, but a bacterial subpopulation tolerates prolonged drug exposure. We evaluated drug-tolerant bacilli in human sputum by comparing messenger RNA (mRNA) expression of drug-tolerant bacilli that survive the early bactericidal phase with treatment-naive bacilli. METHODS: M. tuberculosis gene expression was quantified via reverse-transcription polymerase chain reaction in serial sputa from 17 Ugandans treated for drug-susceptible pulmonary tuberculosis. RESULTS: Within 4 days, bacterial mRNA abundance declined >98%, indicating rapid killing. Thereafter, the rate of decline slowed >94%, indicating drug tolerance. After 14 days, 16S ribosomal RNA transcripts/genome declined 96%, indicating slow growth. Drug-tolerant bacilli displayed marked downregulation of genes associated with growth, metabolism, and lipid synthesis and upregulation in stress responses and key regulatory categories-including stress-associated sigma factors, transcription factors, and toxin-antitoxin genes. Drug efflux pumps were upregulated. The isoniazid stress signature was induced by initial drug exposure, then disappeared after 4 days. CONCLUSIONS: Transcriptional patterns suggest that drug-tolerant bacilli in sputum are in a slow-growing, metabolically and synthetically downregulated state. Absence of the isoniazid stress signature in drug-tolerant bacilli indicates that physiological state influences drug responsiveness in vivo. These results identify novel drug targets that should aid in development of novel shorter tuberculosis treatment regimens.

Subretinal neovascular membranes complicating uveitis: frequency, treatments, and visual outcome.

PURPOSE: Retrospective evaluation in a uveitic population of subretinal neovascular membranes (SRNMs), their occurrence, visual impact, and outcome in differently treated subgroups of patients. METHODS: Medical records of patients were reviewed and cases with SRNM (n = 12) identified. Intraocular inflammation was classified according to vitreous examination records as high (2+ cells), low (1/2+ to 1+ cells), or inactive (0 cells). Visual outcome was considered to be +VA (same or gain of one or more Snellen lines) or -VA (loss of Snellen lines). In nine cases, treatment consisted of the oral administration of high doses of corticosteroids (CST) for one month, tapered down in favorable situations (+VA or SRNM angiographic regression) or maintained at half the dose in unfavorable situations (-VA or SRNM angiographic progression) while additional laser therapies, including photodynamic therapy (PDT), transpupillary thermotherapy (TTT), or argon laser therapy (CLT)), were performed in some of the cases. The above treatment scheme was not applied in three cases (pre-PDT period; undiagnosed underlying uveitis treated without CST). RESULTS: Twelve out of 648 patients (1.9%) with uveitis developed SRNM. The mean visual impact was 4.5 Snellen lines and mean follow-up time was 19.5 months. Two patients with high intraocular inflammation had a favorable visual outcome with CST alone. Eight patients with low intraocular inflammation had a favorable visual outcome with CST alone in three cases, with additional laser therapy in four cases (PDT in 3 cases and TTT in 1 case), and exclusively with PDT in one case (undiagnosed uveitis). Two patients with no intraocular inflammation had unfavorable visual outcome with CST alone (no PDT/TTT available). CONCLUSION: SRNMs occurred as a rare complication of uveitis. Their visual outcome was relatively favorable. Although high doses of CST seem to be the first step in the management of SRNMs, alternative laser treatments should be considered early, especially in cases of absence or low intraocular inflammation.

Substance abuse among Southeast Asians in the U.S.: implications for practice and research.

The literature on Asian-American substance use has shown a general increase in consumption and related problems due, in part, to the effects of acculturation toward U.S. drinking norms. Southeast Asians are the most recent of Asian groups to come to the U.S., and have done so following an immigration and refugee experience that was among the most traumatic in recent memory resulting in significant levels of psychosocial distress. The combined influences of mental health disorders, which frequently co-occur with substance abuse, and acculturation pressures suggest that a significant increase in substance abuse problems may be in progress for Southeast Asian immigrants. Preliminary evidence appears to bear out this hypothesis. The current article outlines the literature on substance abuse among Vietnamese, Cambodians and Laotians in the U.S., and makes tentative recommendations for assessment, treatment and future research.

Age differences in the acculturation process.

Age differences were assessed in a conceptual model that seeks to explain how acculturation affects psychological well-being among Mexican Americans. The data were from a national probability sample of 859 persons of Mexican decent. It was hypothesized that low acculturation creates financial stress. Moreover, low acculturation and financial stress were in turn predicted to erode feelings of personal control and self-esteem. Finally, diminished feelings of control and low self-esteem were hypothesized to exert a negative impact on psychological well-being. When data from respondents of all ages was assessed, empirical support was found for all of the hypotheses except the linkage between acculturation and financial stress. However, few age differences emerged in the model. The authors conclude that older Mexican Americans may not be more vulnerable to the stressors associated with acculturation.

Generational differences in the structure of the CES-D scale in Mexican Americans.

This study examines differences in the structure of the Center for Epidemiologic Studies Depression (CES-D) scale across three generations of Mexican Americans. The covariance structure of the items was viewed as a function of several parameter matrices. Factorial invariance was evaluated by testing a series of hypotheses involving equivalence constraints on one or more parameter matrices. The findings revealed that the proposed 12-item model fits the data within each of the three generations adequately. Although no generational differences in factor loadings were revealed, structural variations of the CES-D in measurement error variances were found. Measurement error variances associated with certain items in the older generation are significantly greater than those in the middle-aged and young generations. In addition, socioeconomic characteristics, acculturation, and health status fail to explain the observed differences in the structure of the CES-D among the three generations.

Stress and religious involvement among older blacks.

We conducted this study in a nationwide sample of older Black Americans to determine whether religious involvement helps to reduce the negative impact of stressful life events. The major outcome measures were self-esteem and feelings of personal control. Three models of the stress process were evaluated empirically: the suppressor, moderator, and distress-deterrent models. The data provided support for the distress-deterrent model only. The findings from this model indicated that although life stress to erode feelings of self-worth and mastery, these negative effects were offset or counterbalanced by increased religious involvement.