Encapsulation of Upconversion Nanoparticles in Periodic Mesoporous Organosilicas.

(1) Background: Nanomedicine has recently emerged as a promising field, particularly for cancer theranostics. In this context, nanoparticles designed for imaging and therapeutic applications are of interest. We, therefore, studied the encapsulation of upconverting nanoparticles in mesoporous organosilica nanoparticles. Indeed, mesoporous organosilica nanoparticles have been shown to be very efficient for drug delivery, and upconverting nanoparticles are interesting for near-infrared and X-ray computed tomography imaging, depending on the matrix used. (2) Methods: Two different upconverting-based nanoparticles were synthesized with Yb3+-Er3+ as the upconverting system and NaYF4 or BaLuF5 as the matrix. The encapsulation of these nanoparticles was studied through the sol-gel procedure with bis(triethoxysilyl)ethylene and bis(triethoxysilyl)ethane in the presence of CTAB. (3) Results: with bis(triethoxysilyl)ethylene, BaLuF5: Yb3+-Er3+, nanoparticles were not encapsulated, but anchored on the surface of the obtained mesoporous nanorods BaLuF5: Yb3+-Er3+@Ethylene. With bis(triethoxysilyl)ethane, BaLuF5: Yb3+-Er3+ and NaYF4: Yb3+-Er3+nanoparticles were encapsulated in the mesoporous cubic structure leading to BaLuF5: Yb3+-Er3+@Ethane and NaYF4: Yb3+-Er3+@Ethane, respectively. (4) Conclusions: upconversion nanoparticles were located on the surface of mesoporous nanorods obtained by hydrolysis polycondensation of bis(triethoxysilyl)ethylene, whereas encapsulation occurred with bis(triethoxysilyl)ethane. The later nanoparticles NaYF4: Yb3+-Er3+@Ethane or BaLuF5: Yb3+-Er3+@Ethane were promising for applications with cancer cell imaging or X-ray-computed tomography respectively.

Optimization of the shelf life of lamb forelegs packed in different multilayer polymeric materials and modified atmospheres.

Lamb forelegs were packed in three different gas mixtures (Treatment N2: 70% N2-30% CO2; Treatment O2: 70% O2-30% CO2; Treatment Ar: 70% Ar-30% CO2) and two types of polymeric materials (B1, a polyamide-polypropylene bag and B2, a bag made of bio-oriented polyamide, aluminium and polyethylene). Physical, chemical and microbiological parameters were determined, initially and after 7, 14 and 21 days of storage (3 ± 1 °C). Colour and oxidative stability decreased and the number of microorganisms increased significantly during the storage period. Treatment O2 increased a* and TBARs. Despite the different permeability to O2, shown by the polymeric material (< 6.0 vs . < 0.5 cm3/m2/24 h bar), the different types of packaging did not significantly affect any of the studied parameters. Regarding the atmosphere treatment or type of packaging, these factors did not significantly affect mesophile or Enterobacteriaceae counts either.

Evidence of the negative effect of sexual minority stigma on HIV testing among MSM and transgender women in San Salvador, El Salvador.

A cross sectional survey was administered to 670 men who have sex with men (MSM) and transgender women (TW) in San Salvador through respondent driven sampling to identify determinants of ever testing for HIV using a minority stress framework. A positive association was found between ever testing and older age [adjusted odds ratio (aOR) 2.10], past experience of sexual assault (aOR 2.92), perceiving that most social acquaintances had tested (aOR 1.81), and knowing a PLHIV (aOR 1.94). A negative association was found between homelessness and ever testing (aOR 0.43). Among the MSM sub-sample (n = 506), similar results were found for older age (aOR 2.63), and past experience of sexual assault (aOR 2.56). Internalized homonegativity was negatively associated with ever testing for HIV among MSM (aOR 0.46), and HIV testing stigma and experienced provider discrimination further strengthened this relationship. It is important to mitigate sexual minority stigma in order to increase HIV testing among MSM. Future research should explore this construct among TW.

Correlates of bisexual behaviors among men who have sex with men in El Salvador.

Bisexual behaviors may increase transmission pathways of HIV and sexually transmitted infections (STIs) from a higher prevalence group to lower prevalence groups in El Salvador. In 2008, men who have sex with men (MSM) were recruited in San Salvador and San Miguel using respondent driven sampling. Participants were interviewed and tested for HIV and STIs. Sixteen seeds and 797 MSM participated; 34.9% in San Salvador and 58.8% in San Miguel reported bisexual behavior. Bisexual behavior was associated with drug use (adjusted odds ratio (AOR) = 2.57, 95% CI: 1.30-5.06) and insertive anal sex (AOR = 5.45, 95% CI: 3.01-9.87), and inversely associated with having a stable male partner (AOR = 0.47, 95% CI: 0.26-0.84) and disclosing MSM behavior to family (AOR = 0.41, 95% CI: 0.22-0.75). Bisexual behavior was associated with risk behaviors with male and female partners that may be associated with HIV and STI transmission. Bisexual men displayed a distinct identity calling for tailored interventions.

Prevalence of transmitted HIV-1 drug resistance among female sex workers and men who have sex with men in El Salvador, Central America.

Transmitted drug resistance has important implications for the successful use and management of therapy among persons infected with HIV. We estimated the prevalence of transmitted drug resistance in 145 samples from female sex workers (n = 47) and men who have sex with men (n = 98) in El Salvador. Samples were collected during March to September 2008, using a respondent driven sampling. The HIV-1 pol gene was sequenced to identify drug resistance mutations and transmitted drug resistance was scored as recommended by World Health Organization. Specimens were classified as recent or established infections using the Immunoglobulin G-Capture BED-Enzyme Immunoassay. The overall prevalence of transmitted drug resistance was 9.4% (95% CI: 4.7-16.1%), and was 5.9% for non-nucleoside reverse transcriptase inhibitors, 4.2% for nucleoside reverse transcriptase inhibitors, and 0.8% for protease inhibitors. Transmitted drug resistance prevalence was 10.3% (95% CI: 2.8-24.2%) among female sex workers, and 9.0% (95% CI: 3.6-17.6%) among men who have sex with men. Nineteen patients were classified as having recent infection (16.2%, 95% CI: 10.1-24.2%), while 98 patients (83.8%, 95% CI: 75.8-89.9%) were classified as having established infections. Transmitted drug resistance among recent and established infections was similar at 10.5% and 9.2%, respectively. This study shows that the prevalence of transmitted drug resistance is moderate among female sex workers and men who have sex with men in El Salvador. These results highlight the importance of transmitted drug resistance surveillance in a representative sample of recently infected patients following the World Health Organization guidelines.

HIV and STI control in El Salvador: results from an integrated behavioural survey among men who have sex with men.

OBJECTIVE: This cross-sectional study investigates HIV, other sexually transmitted infections (STI), and risk behaviours among men who have sex with men (MSM) in two cities in El Salvador. METHODS: Respondent-driven sampling (RDS) was used to recruit MSM in the cities of San Salvador and San Miguel, El Salvador. Participants responded to questions about HIV risk behaviours; and blood, urine and anal swabs were collected. Blood samples were tested for herpes simplex type 2, syphilis and HIV infection. Urine and anal samples were tested by polymerase chain reaction (PCR) for Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium. HIV-positive samples were tested with the BED capture enzyme immunoassay to distinguish recent from longstanding HIV infection. We estimated population-adjusted prevalence of behavioural variables, STI and HIV, and identified risk factors for HIV. RESULTS: The final sample included 596 and 195 MSM in San Salvador and San Miguel, respectively. Consistent condom use was low across all partner types as was recent HIV testing. RDS-adjusted HIV prevalence was 10.8% (95% CI 7.4% to 14.7%) in San Salvador, and 8.8% (95% CI 4.2% to 14.5%) in San Miguel. The proportion of recent testing among HIV-positive samples was 20%. Prevalence of any bacterial STI by PRC testing was 12.7% (95% CI 8.2% to 17.5%) in San Salvador, and 9.6% (95% CI 4.9% to 15.4%) in San Miguel. CONCLUSIONS: We found a high prevalence of HIV, high levels of recent infection, and low condom usage. In El Salvador, targeted interventions towards MSM are needed to promote condom use, as well as to diagnose, treat and prevent HIV and other STIs.

Social network characteristics and HIV vulnerability among transgender persons in San Salvador: identifying opportunities for HIV prevention strategies.

The purpose of this study is to improve understanding of HIV vulnerability and opportunities for HIV prevention within the social networks of male-to-female transgender persons in San Salvador, El Salvador. We compare HIV prevalence and behavioral data from a sample of gay-identified men who have sex with men (MSM) (n = 279), heterosexual or bisexual identified MSM (n = 229) and transgender persons (n = 67) recruited using Respondent Driven Sampling. Transgender persons consistently reported higher rates of HIV risk behavior than the rest of the study population and were significantly more likely to be involved in sex work. While transgender persons reported the highest rates of exposure to HIV educational activities they had the lowest levels of HIV-related knowledge. Transgender respondents' social networks were homophilous and efficient at recruiting other transgender persons. Findings suggest that transgender social networks could provide an effective and culturally relevant opportunity for HIV prevention efforts in this vulnerable population.

Performance and comparison of self-reported STI symptoms among high-risk populations - MSM, sex workers, persons living with HIV/AIDS - in El Salvador.

Resource-limited countries have limited laboratory capability and rely on syndromic management to diagnose sexually transmitted infections (STIs). We aimed to estimate the sensitivity, specificity and positive predictive value (PPV) of STI syndromic management when used as a screening method within a study setting. Men who have sex with men (MSM), female sex workers (FSWs) and people living with HIV/AIDS (PLWHA) participated in a behavioural surveillance study. Data were obtained on demographics, sexual behaviours, STI history and service utilisation. Biological specimens were tested for genital inflammatory infections (Neisseria gonorrhoeae [GC], Chlamydia trachomatis [CT], Mycoplasma genitalium [MG], Trichomonas vaginalis [TV]) and genital ulcerative infection (syphilis and Herpes simplex virus-2). There was a high prevalence of Herpes simplex virus-2 (MSM 48.1%, FSW 82.0% and PLWHA 84.4%). Most participants reported no ulcerative symptoms and the majority of men reported no inflammatory symptoms. Sensitivity and PPV were poor for inflammatory infections among PLWHA and MSM. Sensitivity in FSWs for inflammatory infections was 75%. For ulcerative infections, sensitivity was poor, but specificity and PPV were high. Reliance on self-reported symptoms may not be an effective screening strategy for these populations. STI prevention studies should focus on symptom recognition and consider routine screening and referral for high-risk populations.

Social network-based recruitment successfully reveals HIV-1 transmission networks among high-risk individuals in El Salvador.

OBJECTIVE: HIV in Central America is concentrated among certain groups such as men who have sex with men (MSM) and female sex workers (FSWs). We compared social recruitment chains and HIV transmission clusters from 699 MSM and 787 FSWs to better understand factors contributing to ongoing HIV transmission in El Salvador. METHODS: Phylogenies were reconstructed using pol sequences from 119 HIV-positive individuals recruited by respondent-driven sampling (RDS) and compared with RDS chains in 3 cities in El Salvador. Transmission clusters with a mean pairwise genetic distance ≤ 0.015 and Bayesian posterior probabilities =1 were identified. Factors associated with cluster membership were evaluated among MSM. RESULTS: Sequences from 34 (43%) MSM and 4 (10%) FSW grouped in 14 transmission clusters. Clusters were defined by risk group (12 MSM clusters) and geographic residence (only 1 spanned separate cities). In 4 MSM clusters (all n = 2), individuals were also members of the same RDS chain, but only 2 had members directly linked through recruitment. All large clusters (n ≥ 3) spanned >1 RDS chain. Among MSM, factors independently associated with cluster membership included recent infection by BED assay (P = 0.02), sex with stable male partners (P = 0.02), and sex with ≥ 3 male partners in the past year (P = 0.04). CONCLUSIONS: We found few HIV transmissions corresponding directly with the social recruitment. However, we identified clustering in nearly one-half of MSM suggesting that RDS recruitment was indirectly but successfully uncovering transmission networks, particularly among recent infections. Interrogating RDS chains with phylogenetic analyses may help refine methods for identifying transmission clusters.