Susceptibility Status of a Recently Introduced Population of Aedes albopictus to Insecticides Used by the Vector Control Program in Merida, Yucatan, Mexico.

In recent years, Aedes albopictus has become the most important invasive mosquito species worldwide. In 2018, Ae. albopictus was found in a suburban area of Merida, one of the cities with the highest number of arbovirus cases in Mexico in the last 10 years. As Ae. albopictus continues its range expansion, there is a need to monitor its susceptibility to existing insecticide classes, since countries like Mexico currently do not consider Ae. albopictus in its insecticide management programs. In order to determine its susceptibility to the insecticides usually applied by the vector control program in Mexico, the Centers for Disease Control and Prevention bottle bioassays were performed on individuals from established population of Ae. albopictus from Merida, Yucatan, Mexico. Results suggested that the population recently found in the suburban area of Merida is susceptible to permethrin, deltamethrin, chlorpyrifos, malathion, bendiocarb, and propoxur. Further studies of insecticide resistance using biochemical and molecular tools together with more knowledge of the biology and ecology of this species are necessary to generate specific and efficient control strategies in Mexico.

Understanding How Staphylococcal Autolysin Domains Interact With Polystyrene Surfaces.

Biofilms, when formed on medical devices, can cause malfunctions and reduce the efficiency of these devices, thus complicating treatments and serving as a source of infection. The autolysin protein of Staphylococcus epidermidis contributes to its biofilm forming ability, especially on polystyrene surfaces. R2ab and amidase are autolysin protein domains thought to have high affinity to polystyrene surfaces, and they are involved in initial bacterial attachment in S. epidermidis biofilm formation. However, the structural details of R2ab and amidase binding to surfaces are poorly understood. In this study, we have investigated how R2ab and amidase influence biofilm formation on polystyrene surfaces. We have also studied how these proteins interact with polystyrene nanoparticles (PSNPs) using biophysical techniques. Pretreating polystyrene plates with R2ab and amidase domains inhibits biofilm growth relative to a control protein, indicating that these domains bind tightly to polystyrene surfaces and can block bacterial attachment. Correspondingly, we find that both domains interact strongly with anionic, carboxylate-functionalized as well as neutral, non-functionalized PSNPs, suggesting a similar binding interaction for nanoparticles and macroscopic surfaces. Both anionic and neutral PSNPs induce changes to the secondary structure of both R2ab and amidase as monitored by circular dichroism (CD) spectroscopy. These changes are very similar, though not identical, for both types of PSNPs, suggesting that carboxylate functionalization is only a small perturbation for R2ab and amidase binding. This structural change is also seen in limited proteolysis experiments, which exhibit substantial differences for both proteins when in the presence of carboxylate PSNPs. Overall, our results demonstrate that the R2ab and amidase domains strongly favor adsorption to polystyrene surfaces, and that surface adsorption destabilizes the secondary structure of these domains. Bacterial attachment to polystyrene surfaces during the initial phases of biofilm formation, therefore, may be mediated by aromatic residues, since these residues are known to drive adsorption to PSNPs. Together, these experiments can be used to develop new strategies for biofilm eradication, ensuring the proper long-lived functioning of medical devices.

FAIMS-MS might contribute to phosphopeptides identification in plasma.

FAIMS interface is gaining popularity because of the impressive 100-fold signal to noise enhancement in addition to the recent coupling to the Orbitrap technology, the most important analyzer developed in the last 20 years. The selection of group of ions and effective removal of single-charged ones at particular compensation voltages increases around 50% the proteome coverage at expenses of lower peptides coverage. However, specific setting for phosphoproteome analysis is yet poorly described. Here we have found the maximum transmission for several tryptic phosphopeptides isolated from a single complex mixture and we have set an experimental method based on five compensation voltages partially different to the ones described previously, demonstrating the relevance of voltages higher than 47 V, with an increase of around 20% of unique phosphopeptides. Using this experimental setup two complex phosphoproteomes isolates (SH-SY5Y cell line and plasma) were analyzed and found increments of 50% on phosphopeptides identification with the proposed method with respect to a previous one, for the cell line extract. Meanwhile for plasma 109 of the detected phosphopeptides are found for first time in this body fluid, presumably due to the release of intracellular proteins. With this FAIMS setup, 60% of the proteins identified are classified as very low abundant proteins.

Using NMR Spectroscopy To Measure Protein Binding Capacity on Gold Nanoparticles.

A simple one-dimensional 1H NMR experiment that quantifies protein bound to gold nanoparticles has been developed for upper-division biochemistry and physical chemistry students. This laboratory experiment teaches the basics of NMR techniques, which is a highly effective tool in protein studies and supports students to understand the concepts of NMR spectroscopy and nanoparticle-protein interactions. Understanding the interactions of gold nanoparticles (AuNPs) with biological macromolecules is becoming increasingly important as interest in the clinical use of nanoparticles has been on the rise. Applications in drug delivery, biosensing, diagnostics, and enhanced imaging are all tangible possibilities with a better understanding of AuNP-protein interactions. The ability to use AuNPs as biosensors for drug delivery methods in cellular uptake is dependent on the amount of protein that is able to bind to the surface of the nanoparticle. This laboratory experiment solidifies concepts such as quantitative NMR spectroscopy while reinforcing precision laboratory titrations. Students learn how 1H proton NMR spectra can be used to measure free protein in solution and protein bound to AuNPs. A simple formula is used to determine the binding capacity of the nanoparticle. This analysis helps students to understand the impact of nanoparticle-protein interactions, and it allows them to conceptualize macromolecular binding using NMR spectroscopy.

Surface Plasmon Resonance, Formation Mechanism, and Surface Enhanced Raman Spectroscopy of Ag+-Stained Gold Nanoparticles.

A series of recent works have demonstrated the spontaneous Ag+ adsorption onto gold surfaces. However, a mechanistic understanding of the Ag+ interactions with gold has been controversial. Reported herein is a systematic study of the Ag+ binding to AuNPs using several in-situ and ex-situ measurement techniques. The time-resolved UV-vis measurements of the AuNP surface plasmonic resonance revealed that the silver adsorption proceeds through two parallel pseudo-first order processes with a time constant of 16(±2) and 1,000(±35) s, respectively. About 95% of the Ag+ adsorption proceeds through the fast adsorption process. The in-situ zeta potential data indicated that this fast Ag+ adsorption is driven primarily by the long-range electrostatic forces that lead to AuNP charge neutralization, while the time-dependent pH data shows that the slow Ag+ binding process involves proton-releasing reactions that must be driven by near-range interactions. These experimental data, together with the ex-situ XPS measurement indicates that adsorbed silver remains cationic, but not as a charged-neutral silver atom proposed by the anti-galvanic reaction mechanism. The surface-enhanced Raman activities of the Ag+-stained AuNPs are slightly higher than that for AuNPs, but significantly lower than that for the silver nanoparticles (AgNPs). The SERS feature of the ligands on the Ag+-stained AuNPs can differ from that on both AuNPs and AgNPs. Besides the new insights to formation mechanism, properties, and applications of the Ag+-stained AuNPs, the experimental methodology presented in this work can also be important for studying nanoparticle interfacial interactions.

Protein Interactions with Nanoparticle Surfaces: Highlighting Solution NMR Techniques.

In the last decade, nanoparticles (NPs) have become a key tool in medicine and biotechnology as drug delivery systems, biosensors and diagnostic devices. The composition and surface chemistry of NPs vary based on the materials used: typically organic polymers, inorganic materials, or lipids. Nanoparticle classes can be further divided into sub-categories depending on the surface modification and functionalization. These surface properties matter when NPs are introduced into a physiological environment, as they will influence how nucleic acids, lipids, and proteins will interact with the NP surface. While small-molecule interactions are easily probed using NMR spectroscopy, studying protein-NP interactions using NMR introduces several challenges. For example, globular proteins may have a perturbed conformation when attached to a foreign surface, and the size of NP-protein conjugates can lead to excessive line broadening. Many of these challenges have been addressed, and NMR spectroscopy is becoming a mature technique for in situ analysis of NP binding behavior. It is therefore not surprising that NMR has been applied to NP systems and has been used to study biomolecules on NP surfaces. Important considerations include corona composition, protein behavior, and ligand architecture. These features are difficult to resolve using classical surface and material characterization strategies, and NMR provides a complementary avenue of characterization. In this review, we examine how solution NMR can be combined with other analytical techniques to investigate protein behavior on NP surfaces.

Electrostatic Interactions and Protein Competition Reveal a Dynamic Surface in Gold Nanoparticle-Protein Adsorption.

Gold nanoparticle- (AuNP-) protein conjugates are potentially useful in a broad array of diagnostic and therapeutic applications, but the physical basis of the simultaneous adsorption of multiple proteins onto AuNP surfaces remains poorly understood. Here, we investigate the contribution of electrostatic interactions to protein-AuNP binding by studying the pH-dependent binding behavior of two proteins, GB3 and ubiquitin. For both proteins, binding to 15-nm citrate-coated AuNPs closely tracks with the predicted net charge using standard pKa values, and a dramatic reduction in binding is observed when lysine residues are chemically methylated. This suggests that clusters of basic residues are involved in binding, and using this hypothesis, we model the pKa shifts induced by AuNP binding. Then, we employ a novel NMR-based approach to monitor the binding competition between GB3 and ubiquitin in situ at different pH values. In light of our model, the NMR measurements reveal that the net charge, binding association constant, and size of each protein play distinct roles at different stages of protein adsorption. When citrate-coated AuNPs and proteins first interact, net charge appears to dominate. However, as citrate molecules are displaced by protein, the surface chemistry changes, and the energetics of binding becomes far more complex. In this case, we observed that GB3 is able to displace ubiquitin at intermediate time scales, even though it has a lower net charge. The thermodynamic model for binding developed here could be the first step toward predicting the binding behavior in biological fluids, such as blood plasma.

Computer vision syndrome among computer office workers in a developing country: an evaluation of prevalence and risk factors.

BACKGROUND: Computer vision syndrome (CVS) is a group of visual symptoms experienced in relation to the use of computers. Nearly 60 million people suffer from CVS globally, resulting in reduced productivity at work and reduced quality of life of the computer worker. The present study aims to describe the prevalence of CVS and its associated factors among a nationally-representative sample of Sri Lankan computer workers. METHODS: Two thousand five hundred computer office workers were invited for the study from all nine provinces of Sri Lanka between May and December 2009. A self-administered questionnaire was used to collect socio-demographic data, symptoms of CVS and its associated factors. A binary logistic regression analysis was performed in all patients with 'presence of CVS' as the dichotomous dependent variable and age, gender, duration of occupation, daily computer usage, pre-existing eye disease, not using a visual display terminal (VDT) filter, adjusting brightness of screen, use of contact lenses, angle of gaze and ergonomic practices knowledge as the continuous/dichotomous independent variables. A similar binary logistic regression analysis was performed in all patients with 'severity of CVS' as the dichotomous dependent variable and other continuous/dichotomous independent variables. RESULTS: Sample size was 2210 (response rate-88.4%). Mean age was 30.8 ± 8.1 years and 50.8% of the sample were males. The 1-year prevalence of CVS in the study population was 67.4%. Female gender (OR: 1.28), duration of occupation (OR: 1.07), daily computer usage (1.10), pre-existing eye disease (OR: 4.49), not using a VDT filter (OR: 1.02), use of contact lenses (OR: 3.21) and ergonomics practices knowledge (OR: 1.24) all were associated with significantly presence of CVS. The duration of occupation (OR: 1.04) and presence of pre-existing eye disease (OR: 1.54) were significantly associated with the presence of 'severe CVS'. CONCLUSIONS: Sri Lankan computer workers had a high prevalence of CVS. Female gender, longer duration of occupation, higher daily computer usage, pre-existing eye disease, not using a VDT filter, use of contact lenses and higher ergonomics practices knowledge all were associated with significantly with the presence of CVS. The factors associated with the severity of CVS were the duration of occupation and presence of pre-existing eye disease.

Understanding Protein Structure Deformation on the Surface of Gold Nanoparticles of Varying Size.

Gold nanoparticles (AuNPs) have been of recent interest due to their unique optical properties and their biocompatibility. Biomolecules spontaneously adsorb to their surface, a trait that could potentially be exploited for drug targeting. Currently, it is unclear whether protein-AuNP interactions at the nanoparticle surface are dependent on nanoparticle size. In this work, we investigate whether varying surface curvature can induce protein unfolding and multilayer binding in citrate-coated AuNPs of various sizes. A recently developed NMR-based approach was utilized to determine the adsorption capacity, and protein NMR spectra were compared to determine whether nanoparticle size influences protein interactions at the surface. In addition, transmission electron microscopy (TEM) and dynamic light scattering (DLS) were employed to corroborate the NMR studies. Over a broad range of AuNP sizes (14-86 nm), we show that adsorption capacity can be predicted by assuming that proteins are compact and globular on the nanoparticle surface. Additionally, roughly one layer of proteins is adsorbed regardless of AuNP size. Our results hold for two proteins of significantly different sizes, GB3 (6 kDa) and bovine carbonic anhydrase (BCA, 29 kDa). However, the unstable drkN SH3 domain (ΔG0 ≈ 0, 7 kDa) does not appear to follow the same trend seen for stable, globular proteins. This observation suggests that unstable proteins can deform significantly when bound to AuNP surfaces. Taken together, the results of this work can be used to improve our knowledge of the mechanism of protein-AuNP interactions to optimize their use in the biomedical field.

Optimizing CIGB-300 intralesional delivery in locally advanced cervical cancer.

BACKGROUND: We conducted a phase 1 trial in patients with locally advanced cervical cancer by injecting 0.5 ml of the CK2-antagonist CIGB-300 in two different sites on tumours to assess tumour uptake, safety, pharmacodynamic activity and identify the recommended dose. METHODS: Fourteen patients were treated with intralesional injections containing 35 or 70 mg of CIGB-300 in three alternate cycles of three consecutive days each before standard chemoradiotherapy. Tumour uptake was determined using (99)Tc-radiolabelled peptide. In situ B23/nucleophosmin was determined by immunohistochemistry. RESULTS: Maximum tumour uptake for CIGB-300 70-mg dose was significantly higher than the one observed for 35 mg: 16.1 ± 8.9 vs 31.3 ± 12.9 mg (P = 0.01). Both, AUC24h and biological half-life were also significantly higher using 70 mg of CIGB-300 (P < 0.001). Unincorporated CIGB-300 diffused rapidly to blood and was mainly distributed towards kidneys, and marginally in liver, lungs, heart and spleen. There was no DLT and moderate allergic-like reactions were the most common systemic side effect with strong correlation between unincorporated CIGB-300 and histamine levels in blood. CIGB-300, 70 mg, downregulated B23/nucleophosmin (P = 0.03) in tumour specimens. CONCLUSION: Intralesional injections of 70 mg CIGB-300 in two sites (0.5 ml per injection) and this treatment plan are recommended to be evaluated in phase 2 studies.

Customised symphysio fundal height charts.

OBJECTIVES: To evaluate the feasibility, applicability and the value of customised symphysio fundal height (SFH) charts developed for women of Indian origin in the United Kingdom (UK: CSFH - In chart) and women of African origin in the UK (CSFH - Af chart) in detecting fetal growth restriction and predicting low birth weight (LBW) of the neonate in a Lankan population, and to compare these results with the results obtained from the SFH chart currently used in Sri Lanka (FHB chart) and another SFH chart which uses a range of plus or minus 2-3 cm of the value of the gestational age in weeks as the reference range (GA ± 2 to 3 cm chart). METHODS: Pregnant women (n = 416) with confirmed periods of gestation (POG) of <22 weeks and having a singleton fetus and with no obstetric complications, had their age, parity, POG and Body Mass Index (BMI) documented. Their SFH were measured at four weekly, fortnightly and weekly intervals between 20 - 28, 28 - 36 and 37 - 41 weeks respectively and plotted on the CSFH - In chart, CSFH - Af chart, FHB chart and the GA ± 2 to 3 cm chart. The gestational age at delivery and the birth weight were recorded. Pre term deliveries were excluded leaving 401 participants for analysis. RESULTS: There were 164 (39.4 %) primigravidae, 76 (18.9 %) had low BMI and 71 (17.7 %) had a high BMI. Maternal BMI at booking was positively correlated to the birth weight of the baby but not the parity. In detecting LBW at term, the CSFH - In chart had the best sensitivity, specificity, positive predictive value, negative predictive value, and the likelihood ratios. Of the two non customised charts the GA ± 2 to 3 cm chart was better than the FHB chart. CONCLUSIONS: Until a customised SFH chart is developed for Sri Lanka, the CSFH - In chart or the GA ± 2 to 3 cm chart should be used for antenatal monitoring of fetal growth.

The process and costs of publishing medical journals in Sri Lanka: an economic evaluation.

Objectives Medical journals have contributed to the advancement of medicine by helping to disseminate scientific knowledge and providing a forum for medical communities to debate issues in depth. To the authors' knowledge, there are no studies examining the process of medical journal publication in developing Asian countries. The authors analysed the process and costs of publishing medical journals in Sri Lanka, a developing country in South Asia. Methods Data were collected by interviewing the editors and perusing the records at the editorial offices of the respective medical journals. Articles published in 2009 (or 2008 for journals not published in 2009) were analysed by perusing the respective journals. Results A total of 44 medical journals were published in Sri Lanka's history, of which only 28 journals remained in publication after 2007. A majority (54%) of the journals published after 2007 were published once per year. Seventeen journals in publication after 2007 were published in paper version only, and 11 journals were also available online. The mean cost of printing one issue was Sri Lankan Rupees (LKR) 97 720 (US$888) (range LKR 28 000-270 000). The cost of distribution ranged from LKR 2000 to 140 000 (US$18-1273). The mean cost of publishing one article was LKR 6646 (US$60). A total of 456 articles were published in 2009 (/2008). The total number of pages published was 1723. Conclusion The infrastructure for medical journal publishing in Sri Lanka has many good qualities such as free access, minimum charges for authors and potential for online availability. The journals are solely academic (non-profit), but the costs remain high.

Preoperative testing in elective surgery: Is it really cost effective?

INTRODUCTION: During preoperative preparation, patients undergo investigations to detect asymptomatic diseases. The probability of finding significant abnormalities on such routine investigations is small, and these investigations unnecessarily increase costs of perioperative care. We evaluated current practices, compliance with national guidelines and costs of preoperative investigations at the National Hospital of Sri Lanka (NHSL). MATERIALS AND METHODS: Patients undergoing elective surgery at the general surgical units of the NHSL from June to August 2010 were included in this study. The National Guidelines on Preoperative Investigations were the standard of assessment. Data on preoperative investigations were collected using an expert-validated pretested interviewer-administered questionnaire. RESULTS: Sample size was 2,061 patients. Mean age of the patients was 46.7±15.8 years; males constituted 54.2% of the study population. Majority of the patients were ASA-I (68.5%) and surgical grade II (62.0%). Request for chest X-ray and prothrombin time / international normalized ratio least conformed to the guidelines. Only fasting blood sugar / random blood sugar demonstrated 'good' compliance (>70%) to the guidelines. An 'acceptable' compliance (50%-70%) was seen for electrocardiogram, blood grouping and full blood count. All other investigations demonstrated 'poor' compliance (<50%) with the guidelines. The total excess cost incurred due to non-recommended investigations during the study period of 3 months was Sri Lankan Rupees (LKR.) 1,324,860 to 2,044,210 (per patient LKR. 642.82-991.85). Intern house officers (IHOs) were involved in the planning of preoperative investigations in 2,001 patients (97.1%), followed by medical officeranesthesia / registrar-anesthesia (n=1,625; 78.8%), surgical registrars (n=190; 9.2%), consultant (n=70; 3.4%), senior registrar (n=46; 2.2%) and senior house officers (n=22; 1.1%). Non-recommended investigations were requested mostly by the IHOs and medical officer-anesthesia / registrar-anesthesia. CONCLUSIONS: Unnecessary preoperative investigations are common at our institution, leading to substantially excessive costs. There is ample opportunity to rationalize practices and reduce expenditure.

Immunological and purine enzyme studies on hyperuricaemic and normouricaemic patients with Down's syndrome.

Hyperuricaemia in Down's syndrome is unreleated to the activity of phosphoribosylamidotransfrease, which catalyses the activity of the first specific step on the purine biosynthetic pathway, and to the activity of hypoxanthine phosphoribosyltransferase and phosphoribosylpyrophosphate synthetase, abnormalities of which are known to be associated with hyperuricaemia. Immunological studies involving serum immunoglobulins, natural E. coli antibodies, test immunization with pneumococcal polysaccharide type III (PnPS), in vitro lymphocyte transformation to mitogens, and pokeweed mitogen (PWM) induced immunoglobulin production showed no difference between hyperuricaemic or normouricaemic Down's patients and institutionalized controls. The Down's patients had higher serum IgA, IgG and IgE, and some also produced more immunoglobulin in PWM-stimulated lymphocyte cultures when compared to normal healthy controls. However, both patients with Down's syndrome and the institutionalized controls had significantly lower responses to PnPs than normal healthy controls. The only deficiency confined to the Down's patients was a signficant depression in delayed hypersensitivity to dinitrochlorobenzene. These findings indicate that the in vivo abnormality of depressed cellular and humoral immunity in Down's patients is not paralleled by in vitro function as measured by PHA lymphocyte transformation and immunoglobulin production by PWM-stimulated lymphocytes. There is also no apparent link between a putative defect in purine metabolism in Down's patients and any immunological abnormalities.