Temporal validation of the MMCD score to predict kidney replacement therapy and in-hospital mortality in COVID-19 patients.

BACKGROUND: Acute kidney injury has been described as a common complication in patients hospitalized with COVID-19, which may lead to the need for kidney replacement therapy (KRT) in its most severe forms. Our group developed and validated the MMCD score in Brazilian COVID-19 patients to predict KRT, which showed excellent performance using data from 2020. This study aimed to validate the MMCD score in a large cohort of patients hospitalized with COVID-19 in a different pandemic phase and assess its performance to predict in-hospital mortality. METHODS: This study is part of the "Brazilian COVID-19 Registry", a retrospective observational cohort of consecutive patients hospitalized for laboratory-confirmed COVID-19 in 25 Brazilian hospitals between March 2021 and August 2022. The primary outcome was KRT during hospitalization and the secondary was in-hospital mortality. We also searched literature for other prediction models for KRT, to assess the results in our database. Performance was assessed using area under the receiving operator characteristic curve (AUROC) and the Brier score. RESULTS: A total of 9422 patients were included, 53.8% were men, with a median age of 59 (IQR 48-70) years old. The incidence of KRT was 8.8% and in-hospital mortality was 18.1%. The MMCD score had excellent discrimination and overall performance to predict KRT (AUROC: 0.916 [95% CI 0.909-0.924]; Brier score = 0.057). Despite the excellent discrimination and overall performance (AUROC: 0.922 [95% CI 0.914-0.929]; Brier score = 0.100), the calibration was not satisfactory concerning in-hospital mortality. A random forest model was applied in the database, with inferior performance to predict KRT requirement (AUROC: 0.71 [95% CI 0.69-0.73]). CONCLUSION: The MMCD score is not appropriate for in-hospital mortality but demonstrates an excellent predictive ability to predict KRT in COVID-19 patients. The instrument is low cost, objective, fast and accurate, and can contribute to supporting clinical decisions in the efficient allocation of assistance resources in patients with COVID-19.

Infodemics and health misinformation: a systematic review of reviews.

Objective: To compare and summarize the literature regarding infodemics and health misinformation, and to identify challenges and opportunities for addressing the issues of infodemics. Methods: We searched MEDLINE®, Embase®, Cochrane Library of Systematic Reviews, Scopus and Epistemonikos on 6 May 2022 for systematic reviews analysing infodemics, misinformation, disinformation and fake news related to health. We grouped studies based on similarity and retrieved evidence on challenges and opportunities. We used the AMSTAR 2 approach to assess the reviews' methodological quality. To evaluate the quality of the evidence, we used the Grading of Recommendations Assessment, Development and Evaluation guidelines. Findings: Our search identified 31 systematic reviews, of which 17 were published. The proportion of health-related misinformation on social media ranged from 0.2% to 28.8%. Twitter, Facebook, YouTube and Instagram are critical in disseminating the rapid and far-reaching information. The most negative consequences of health misinformation are the increase of misleading or incorrect interpretations of available evidence, impact on mental health, misallocation of health resources and an increase in vaccination hesitancy. The increase of unreliable health information delays care provision and increases the occurrence of hateful and divisive rhetoric. Social media could also be a useful tool to combat misinformation during crises. Included reviews highlight the poor quality of published studies during health crises. Conclusion: Available evidence suggests that infodemics during health emergencies have an adverse effect on society. Multisectoral actions to counteract infodemics and health misinformation are needed, including developing legal policies, creating and promoting awareness campaigns, improving health-related content in mass media and increasing people's digital and health literacy.

First Report of a Mastrevirus (Geminiviridae) Transmitted by the Corn Leafhopper.

Maize striate mosaic virus (MSMV; genus Mastrevirus) was recently reported in maize plants in Brazil and also detected by metagenomic analyses in the corn leafhopper, Dalbulus maidis (DeLong & Wolcott). Although these findings suggested that D. maidis is a potential vector, no transmission studies have been performed. Here, we tested the transmission of MSMV by D. maidis from field-collected infected plants and plants infected with MSMV via leafhopper-mediated transmission in the laboratory; all plants were confirmed positive for MSMV by PCR. In each one of three transmission replicates, aviruliferous D. maidis nymphs and adults were confined together on a source plant during a 4-day acquisition access period (AAP) and subsequently transferred to healthy maize seedlings (10 individuals per test plant) in a series of 4-day inoculation access periods (IAPs). We also tested transmission by the corn aphid, Rhopalosiphum maidis (Fitch) and by mechanical inoculation of healthy maize seedlings. Only D. maidis transmitted MSMV, with overall transmission rates of 29.4 and 39.5% on field-collected infected plants and 18.5% on infected plants in laboratory. D. maidis transmitted MSMV until the third (8 to 12 days after the AAP) or fourth successive IAP (12 to 16 days), with gradual loss in transmission efficiency and rate of viruliferous insects over time, suggesting a persistent but nonpropagative mode of transmission. Infected test plants showed mottling symptoms with mild chlorotic streaks and height reduction. This is the first report of transmission of a mastrevirus by D. maidis, facilitating the completion of Koch's postulate for MSMV.

Impact of Big Data Analytics on People's Health: Overview of Systematic Reviews and Recommendations for Future Studies.

BACKGROUND: Although the potential of big data analytics for health care is well recognized, evidence is lacking on its effects on public health. OBJECTIVE: The aim of this study was to assess the impact of the use of big data analytics on people's health based on the health indicators and core priorities in the World Health Organization (WHO) General Programme of Work 2019/2023 and the European Programme of Work (EPW), approved and adopted by its Member States, in addition to SARS-CoV-2-related studies. Furthermore, we sought to identify the most relevant challenges and opportunities of these tools with respect to people's health. METHODS: Six databases (MEDLINE, Embase, Cochrane Database of Systematic Reviews via Cochrane Library, Web of Science, Scopus, and Epistemonikos) were searched from the inception date to September 21, 2020. Systematic reviews assessing the effects of big data analytics on health indicators were included. Two authors independently performed screening, selection, data extraction, and quality assessment using the AMSTAR-2 (A Measurement Tool to Assess Systematic Reviews 2) checklist. RESULTS: The literature search initially yielded 185 records, 35 of which met the inclusion criteria, involving more than 5,000,000 patients. Most of the included studies used patient data collected from electronic health records, hospital information systems, private patient databases, and imaging datasets, and involved the use of big data analytics for noncommunicable diseases. "Probability of dying from any of cardiovascular, cancer, diabetes or chronic renal disease" and "suicide mortality rate" were the most commonly assessed health indicators and core priorities within the WHO General Programme of Work 2019/2023 and the EPW 2020/2025. Big data analytics have shown moderate to high accuracy for the diagnosis and prediction of complications of diabetes mellitus as well as for the diagnosis and classification of mental disorders; prediction of suicide attempts and behaviors; and the diagnosis, treatment, and prediction of important clinical outcomes of several chronic diseases. Confidence in the results was rated as "critically low" for 25 reviews, as "low" for 7 reviews, and as "moderate" for 3 reviews. The most frequently identified challenges were establishment of a well-designed and structured data source, and a secure, transparent, and standardized database for patient data. CONCLUSIONS: Although the overall quality of included studies was limited, big data analytics has shown moderate to high accuracy for the diagnosis of certain diseases, improvement in managing chronic diseases, and support for prompt and real-time analyses of large sets of varied input data to diagnose and predict disease outcomes. TRIAL REGISTRATION: International Prospective Register of Systematic Reviews (PROSPERO) CRD42020214048; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=214048.

Dealing with Hydrogen Bonding on the Conformational Preference of 1,3-Aminopropanols: Experimental and Molecular Dynamics Approaches.

This study expands the knowledge on the conformational preference of 1,3-amino alcohols in the gas phase and in solution. By employing Fourier transform infrared spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, density functional theory (DFT) calculations, quantum theory of atoms in molecules (QTAIM), natural bond orbital (NBO) analysis, and molecular dynamics (MD), the compounds 3-aminopropan-1-ol (1), 3-methylaminopropan-1-ol (2), and 3-dimethylaminopropan-1-ol (3) are evaluated. The results show that the most stable conformation of each compound in the gas phase and in nonpolar solvents exhibited an O-H···N intramolecular hydrogen bond (IHB). Based on the experimental and theoretical OH-stretching frequencies, the IHB becomes stronger from 1 to 3. In addition, from the experimental NMR J-couplings, the IHB conformers are predominant in nonbasic solvents, representing 70-80% of the conformational equilibrium, while in basic solvents, such conformers only represent 10%. DFT calculations and QTAIM analysis in the gas phase support the occurrence of IHBs in these compounds. The MD simulation indicates that the non-hydrogen-bonded conformers are the lowest energy conformations in the solution because of molecular interactions with the solvent, while they are absent in the implicit solvation model based on density. NBO analysis suggests that methyl groups attached on the nitrogen atom affect the charge transfer energy involved in the IHB. This effect occurs mostly because of a decrease in the s-character of the LPN orbital along with weakening of the charge transfer from LPN to σ*OH, which is caused by an increase in the C-C-N bond angle.

University and public health system partnership: A real-life intervention to improve asthma management.

OBJECTIVE: Asthma is under-diagnosed in many parts of the world. We aimed to assess the outcome of a capacitating program on asthma for non-specialist physicians and other healthcare professionals working in the public system in Ribeirão Preto, Brazil. METHODS: A group of 16 asthma specialists developed a one-year capacitating program in 11 healthcare clinics in the Northern District of the city, which included lectures on asthma, training on inhalation device use and spirometry, and development of an asthma management protocol. Researchers visited one health unit 2-4 times monthly, working with doctors on patients' care, discussing cases, and delivering lectures. Asthma education was also directed to the general population, focusing on recognition of signs and symptoms and long-term treatment, including production of educational videos available on YouTube. Outcome measures were the records of doctors' prescriptions of individual asthma medications pre- and post-intervention. RESULTS: Prior to the program, 3205 units of inhaled albuterol and 2876 units of inhaled beclomethasone were delivered by the Northern District pharmacy. After the one-year program, there was increase to 4850 units (51.3%) for inhaled albuterol and 3526 units (22.6%) for inhaled beclomethasone. The albuterol increase followed the recommendation given to the non-specialist doctors by the asthma experts, that every patient with asthma should have inhaled albuterol as a rescue medication, by protocol. No increase was observed in other districts where no capacitating program was conducted. CONCLUSION: A systematic capacitating program was successful in changing asthma prescription profiles among non-specialist doctors, with increased delivery of inhaled albuterol and beclomethasone.

Cd hyperfine interactions in DNA bases and DNA of mouse strains infected with Trypanosoma cruzi investigated by perturbed angular correlation spectroscopy and ab initio calculations.

In this work, perturbed angular correlation (PAC) spectroscopy is used to study differences in the nuclear quadrupole interactions of Cd probes in DNA molecules of mice infected with the Y-strain of Trypanosoma cruzi. The possibility of investigating the local genetic alterations in DNA, which occur along generations of mice infected with T. cruzi, using hyperfine interactions obtained from PAC measurements and density functional theory (DFT) calculations in DNA bases is discussed. A comparison of DFT calculations with PAC measurements could determine the type of Cd coordination in the studied molecules. To the best of our knowledge, this is the first attempt to use DFT calculations and PAC measurements to investigate the local environment of Cd ions bound to DNA bases in mice infected with Chagas disease. The obtained results also allowed the detection of local changes occurring in the DNA molecules of different generations of mice infected with T. cruzi, opening the possibility of using this technique as a complementary tool in the characterization of complicated biological systems.

Successful equine in vitro embryo production by ICSI - effect of season, mares' age, breed, and phase of the estrous cycle on embryo production.

This retrospective study aimed at identifying factors that contribute to the success of equine in vitro embryo production by intracytoplasmic sperm injection (ICSI). A total of 7993 ovum pick-up (OPU) sessions were performed, totaling 2540 donor mares and semen from 396 stallions. Oocytes were aspirated at multiple sites in Brazil and were sent to the laboratory, within 6 h from OPU, in pre-maturation medium where they were in vitro matured (IVM) followed by ICSI and in vitro embryo culture for 7-8 days. The number of recovered oocytes, matured oocytes, cleaved embryos and blastocysts were used to explore the effect of age and breed of the donor mare, time of year in which the mare was aspirated and phase of the estrous cycle on the day of follicular aspiration. Mares between 6 and 15 years old were superior to other age groups in most parameters evaluated, including the average number of blastocysts per OPU. The impact of age was similar when evaluated within two breeds, American Quarter Horse (AQHA) and Warmblood mares. We observed that breed (AQHA, Warmblood, Crioulo, Lusitano and Mangalarga) had an important effect on most of the parameter evaluated, including number of oocytes recovered, blastocysts produced per OPU, and blastocyst rates. The overall impact of season was less pronounced than age and breed, with the only statistically significant difference being a higher rate of oocyte maturation during the summer season. Finally, most of the parameters evaluated were superior in follicular phase mares, with or without dominant follicle than luteal phase mares. In conclusion, this retrospective study revealed that breed, age, season and stage of estrous at the time of OPU are all important parameters for the success of equine embryo production by ICSI. This technology enables producing embryos all-year-round from mares of different breeds and ages from OPU-derived oocytes collected at multiple sites.

Structural prediction of a rhodamine-based biosensor and comparison with biophysical data.

The predicted structure has been calculated for a protein-based biosensor for inorganic phosphate (Pi), previously developed by some of us (Okoh et al., Biochemistry, 2006, 45, 14764). This is the phosphate binding protein from Escherichia coli labelled with two rhodamine fluorophores. Classical molecular dynamics and hybrid Car-Parrinello/molecular mechanics simulations allow us to provide molecular models of the biosensor both in the presence and in the absence of Pi. In the latter case, the rhodamine fluorophores maintain a stacked conformation in a 'face A to face B' orientation, which is different from the 'face A to face A' stacked orientation of free fluorophores in aqueous solution (Ilich et al., Spectrochim. Acta, Part A, 1996, 52, 1323). A protein conformation change upon binding Pi prevents significant stacking of the two rhodamines. In both states, the rhodamine fluorophores form hydrophobic contact with LEU291, without establishing significant hydrogen bonds with the protein. The accuracy of the models is established by a comparison between calculated and experimental absorption and circular dichroism spectra.

Yellow Leaf Disease Resistance and Melanaphis sacchari Preference in Commercial Sugarcane Cultivars.

Sugarcane yellow leaf disease (YLD) caused by sugarcane yellow leaf virus (ScYLV) is a major threat for the sugarcane industry worldwide, and the aphid Melanaphis sacchari is its main vector. Breeding programs in Brazil have provided cultivars with intermediate resistance to ScYLV, whereas the incidence of ScYLV has been underestimated partly due to the complexity of YLD symptom expression and identification. Here, we evaluated YLD symptoms in a field assay using eight sugarcane genotypes comprising six well-established commercial high-sucrose cultivars, one biomass yield cultivar, and a susceptible reference under greenhouse conditions, along with estimation of virus titer through RT-qPCR from leaf samples. Additionally, a free-choice bioassay was used to determine the number of aphids feeding on the SCYLV-infected cultivars. Most of the cultivars showed some degree of resistance to YLD, while also revealing positive RT-qPCR results for ScYLV and virus titers with non-significant correlation with YLD severity. The cultivars IACSP01-5503 and IACBIO-266 were similar in terms of aphid preference and ScYLV resistance traits, whereas the least preferred cultivar by M. sacchari, IACSP96-7569, showed intermediate symptoms but similar virus titer to the susceptible reference, SP71-6163. We conclude that current genetic resistance incorporated into sugarcane commercial cultivars does not effectively prevent the spread of ScYLV by its main aphid vector.

Assessment of liquid disposal originated by uranium enrichment at Aramar Experimental Center São Paulo--Brazil.

This work presents a liquid disposal monitoring originated from uranium enrichment process at Aramar Experimental Center from 1990 to 1998. Assessment of uranium, fluorides, ammoniacal nitrogen, chemical oxygen demand, and pH measurements were made in water samples and compared with results achieved in other countries, as North America and India. The liquid disposal evaluation, generated by uranium enrichment process, showed low levels, considering most parameters established by Federal and State Legislation, aiming environmental pollution control. However, uranium levels were above the limits established by Conselho Nacional do Meio Ambiente, Environment Protection Agency and mainly by the World Health Organization.

Multi-modality cardiac imaging in the management of diabetic heart disease.

Diabetic heart disease is a major healthcare problem. Patients with diabetes show an excess of death from cardiovascular causes, twice as high as the general population and those with diabetes type 1 and longer duration of the disease present with more severe cardiovascular complications. Premature coronary artery disease and heart failure are leading causes of morbidity and reduced life expectancy. Multimodality cardiac imaging, including echocardiography, cardiac computed tomography, nuclear medicine, and cardiac magnetic resonance play crucial role in the diagnosis and management of different pathologies included in the definition of diabetic heart disease. In this review we summarise the utility of multi-modality cardiac imaging in characterising ischaemic and non-ischaemic causes of diabetic heart disease and give an overview of the current clinical practice. We also describe emerging imaging techniques enabling early detection of coronary artery inflammation and the non-invasive characterisation of the atherosclerotic plaque disease. Furthermore, we discuss the role of MRI-derived techniques in studying altered myocardial metabolism linking diabetes with the development of diabetic cardiomyopathy. Finally, we discuss recent data regarding the use of artificial intelligence applied to large imaging databases and how those efforts can be utilised in the future in screening of patients with diabetes for early signs of disease.

A quantitative analysis of the impact of explicit incorporation of recency, seasonality and model specialization into fine-grained tourism demand prediction models.

Forecasting is of utmost importance for the Tourism Industry. The development of models to predict visitation demand to specific places is essential to formulate adequate tourism development plans and policies. Yet, only a handful of models deal with the hard problem of fine-grained (per attraction) tourism demand prediction. In this paper, we argue that three key requirements of this type of application should be fulfilled: (i) recency-forecasting models should consider the impact of recent events (e.g. weather change, epidemics and pandemics); (ii) seasonality-tourism behavior is inherently seasonal; and (iii) model specialization-individual attractions may have very specific idiosyncratic patterns of visitations that should be taken into account. These three key requirements should be considered explicitly and in conjunction to advance the state-of-the-art in tourism prediction models. In our experiments, considering a rich set of indoor and outdoor attractions with environmental and social data, the explicit incorporation of such requirements as features into the models improved the rate of highly accurate predictions by more than 320% when compared to the current state-of-the-art in the field. Moreover, they also help to solve very difficult prediction cases, previously poorly solved by the current models. We also investigate the performance of the models in the (simulated) scenarios in which it is impossible to fulfill all three requirements-for instance, when there is not enough historical data for an attraction to capture seasonality. All in all, the main contributions of this paper are the proposal and evaluation of a new information architecture for fine-grained tourism demand prediction models as well as a quantification of the impact of each of the three aforementioned factors on the accuracy of the learned models. Our results have both theoretical and practical implications towards solving important touristic business demands.

Semantic Academic Profiler (SAP): a framework for researcher assessment based on semantic topic modeling.

Recent efforts have focused on identifying multidisciplinary teams and detecting co-Authorship Networks based on exploring topic modeling to identify researchers' expertise. Though promising, none of these efforts perform a real-life evaluation of the quality of the built topics. This paper proposes a Semantic Academic Profiler (SAP) framework that allows summarizing articles written by researchers to automatically build research profiles and perform online evaluations regarding these built profiles. SAP exploits and extends state-of-the-art Topic Modeling strategies based on Cluwords considering n-grams and introduces a new visual interface able to highlight the main topics related to articles, researchers and institutions. To evaluate SAP's capability of summarizing the profile of such entities as well as its usefulness for supporting online assessments of the topics' quality, we perform and contrast two types of evaluation, considering an extensive repository of Brazilian curricula vitae: (1) an offline evaluation, in which we exploit a traditional metric (NPMI) to measure the quality of several data representations strategies including (i) TFIDF, (ii) TFIDF with Bi-grams, (iii) Cluwords, and (iv) CluWords with Bi-grams; and (2) an online evaluation through an A/B test where researchers evaluate their own built profiles. We also perform an online assessment of SAP user interface through a usability test following the SUS methodology. Our experiments indicate that the CluWords with Bi-grams is the best solution and the SAP interface is very useful. We also observed essential differences in the online and offline assessments, indicating that using both together is very important for a comprehensive quality evaluation. Such type of study is scarce in the literature and our findings open space for new lines of investigation in the Topic Modeling area.

Laser-power dependence effects on the structural stability of nanocomposite catalysts studied by Raman spectroscopy: On the structure-activity correlations in glycerol acetylation.

Structural properties of binary CeAl, CeMn, NiAl, CeZr, SnTi and ZrMn nanocomposite oxide catalysts were monitored towards the Laser Raman spectroscopy investigations providing new insights to control catalytic applications upon temperature ranges at which the laser power was varied. The lattice vibrational properties were investigated by varying the incident laser power during Raman measurements from 0.017 mW to 4.0 mW. Structural changes in nanocomposites were achieved upon increasing laser power, which induced local heating disorder causing the sintering of CeMn, SnTi, and ZrMn nanocomposites. The laser-power dependence effects on the structural stability of CeAl, NiAl, and CeZr were observed with high amounts of oxygen vacancy defects over CeAl upon laser power heating. Both CeMn and ZrMn exhibited phase transitions from MnO2 to α-Mn2O3 being the use of the latter nanocomposites limited to work at 1.1 mW. The structure-activity correlations for the nanocomposite oxide catalysts were evaluated through the acetylation of glycerol with acetic acid reaction to produce valuable acetins. Remarkable shifts in the Raman bands wavenumbers and other spectral changes in the lattice mode were caused by laser-induced phenomena accounting for the undesired phase formation and particle growths, as well. This resulted in a low catalytic performance of the NiAl, SnTi, CeMn and ZrMn owing to the thermal effects. Contrary, CeAl and CeZr were more active for acetins products avoiding the phase transformations due to their structural stability at high temperatures, which in turn avoided leaching of the active Ce sites during the reaction.

Good clinical practice recommendations in allergen immunotherapy: Position paper of the Brazilian Association of Allergy and Immunology - ASBAI.

Background: Allergen Immunotherapy (AIT) represents one of the pillars in the treatment of allergic diseases. AIT is the only therapeutic strategy with curative potential, promoting the reduction of drug use and long-term symptom control even after the end of the treatment. The European Academy of Allergy, Asthma and Immunology (EAACI) guidelines, position papers of World Allergy Organization (WAO), and the US Practice Parameters are the leading official documents that set scientific standard for the use of AIT in the world. The use of AIT in Brazil has specific regional conditions due to the pattern of allergen sensitization, as well as genetic, socioeconomic, and cultural characteristics, climate conditions, and the availability of allergenic extracts. The most prevalent house dust mites are Dermatophagoides pteronyssinus, Dermatophagoides farinae and their allergens have the highest clinical relevance. Blomia tropicalis is also very frequent. This position paper has been prepared by the Brazilian Association of Allergy and Clinical Immunology (ASBAI) Taskforce on AIT for respiratory allergy and Hymenoptera venom allergy. Objective: According to the current scientific literature adapted to the Brazilian reality, this position paper aims to establish the main recommendations for the good clinical practice parameters for AIT in Brazil. Methods: A systematic review using the Pub Med and Cochrane databases was performed, and the websites of major allergy and immunology organizations were consulted. The research was limited to English language literature and was conducted between March 30, 2002, and March 30, 2022. The terms used for the research were: Allergen Immunotherapy, sublingual immunotherapy (SLIT), subcutaneous immunotherapy (SCIT), venom-specific immunotherapy (VIT), and allergen extract. Results: The several recommendations that establish the clinical practices for AIT recommended by the main Allergy, Asthma and Immunology world organizations were analyzed and adapted to the Brazilian situation. Conclusion: This position paper establishes the main recommendations for the effective clinical practice of AIT in Brazil, using current knowledge of evidence-based medicine and precision medicine.

A new porphyrin as selective substrate-based inhibitor of breast cancer resistance protein (BCRP/ABCG2).

The ABCG2 transporter plays a pivotal role in multidrug resistance, however, no clinical trial using specific ABCG2 inhibitors have been successful. Although ABC transporters actively extrude a wide variety of substrates, photodynamic therapeutic agents with porphyrinic scaffolds are exclusively transported by ABCG2. In this work, we describe for the first time a porphyrin derivative (4B) inhibitor of ABCG2 and capable to overcome multidrug resistance in vitro. The inhibition was time-dependent and 4B was not itself transported by ABCG2. Independently of the substrate, the porphyrin 4B showed an IC50 value of 1.6 µM and a mixed type of inhibition. This compound inhibited the ATPase activity and increased the binding of the conformational-sensitive antibody 5D3. A thermostability assay confirmed allosteric protein changes triggered by the porphyrin. Long-timescale molecular dynamics simulations revealed a different behavior between the ABCG2 porphyrinic substrate pheophorbide a and the porphyrin 4B. Pheophorbide a was able to bind in three different protein sites but 4B showed one binding conformation with a strong ionic interaction with GLU446. The inhibition was selective toward ABCG2, since no inhibition was observed for P-glycoprotein and MRP1. Finally, this compound successfully chemosensitized cells that overexpress ABCG2. These findings reinforce that substrates may be a privileged source of chemical scaffolds for identification of new inhibitors of multidrug resistance-linked ABC transporters.

Can the vector space model be used to identify biological entity activities?

BACKGROUND: Biological systems are commonly described as networks of entity interactions. Some interactions are already known and integrate the current knowledge in life sciences. Others remain unknown for long periods of time and are frequently discovered by chance. In this work we present a model to predict these unknown interactions from a textual collection using the vector space model (VSM), a well known and established information retrieval model. We have extended the VSM ability to retrieve information using a transitive closure approach. Our objective is to use the VSM to identify the known interactions from the literature and construct a network. Based on interactions established in the network our model applies the transitive closure in order to predict and rank new interactions. RESULTS: We have tested and validated our model using a collection of patent claims issued from 1976 to 2005. From 266,528 possible interactions in our network, the model identified 1,027 known interactions and predicted 3,195 new interactions. Iterating the model according to patent issue dates, interactions found in a given past year were often confirmed by patent claims not in the collection and issued in more recent years. Most confirmation patent claims were found at the top 100 new interactions obtained from each subnetwork. We have also found papers on the Web which confirm new inferred interactions. For instance, the best new interaction inferred by our model relates the interaction between the adrenaline neurotransmitter and the androgen receptor gene. We have found a paper that reports the partial dependence of the antiapoptotic effect of adrenaline on androgen receptor. CONCLUSIONS: The VSM extended with a transitive closure approach provides a good way to identify biological interactions from textual collections. Specifically for the context of literature-based discovery, the extended VSM contributes to identify and rank relevant new interactions even if these interactions occur in only a few documents in the collection. Consequently, we have developed an efficient method for extracting and restricting the best potential results to consider as new advances in life sciences, even when indications of these results are not easily observed from a mass of documents.

Development and evaluation of a floating multiparticulate gastroretentive system for modified release of AZT.

The aim of this study was to develop and evaluate a floating multiparticulate gastroretentive system for the modified release of zidovudine (AZT). AZT was used as a model drug water-soluble at therapeutic doses. The floating gastroretentive system was obtained by co-precipitation, after solvent diffusion and evaporation. The proposed system was evaluated in vitro for particle morphology, lag time and floating time, loading rate, release profile, and the release kinetic of AZT release. AZT's physico-chemical characteristics were evaluated by differential scanning calorimetry (DSC), X-ray diffraction (XDR) and infrared spectroscopy (IR). The particles obtained were sphere-shaped, hollow, and had porous walls. The floating was immediate, and floating time was higher than 12 h. The loading rate was 34.0 ± 9.0%. The system obtained had an extended release. DSC and XDR results showed a modification in AZT's solid state. IR spectroscopy revealed that the chemical structure of the AZT was unchanged. The hollow microballoons presented gastroretentive, floating, and extended-release properties.

Effect of Sugarcane Cultivars Infected with Sugarcane Yellow Leaf Virus (ScYLV) on Feeding Behavior and Biological Performance of Melanaphis sacchari (Hemiptera: Aphididae).

Sugarcane yellow leaf virus (ScYLV), Polerovirus, Luteoviridae, is one of the main viruses that infect sugarcane worldwide. The virus is transmitted by the aphid Melanaphis sacchari in a persistent, circulative manner. To better understand the interactions between ScYLV, sugarcane genotypes and M. sacchari, we explored the effect of sugarcane cultivars on the feeding behavior and biological performance of the vector. The number of nymphs, adults, winged, total number of aphids and dead aphids was assayed, and an electrical penetration graph (EPG) was used to monitor the stylet activities. Multivariate analysis showed changes in the vector's behavior and biology on cultivars, identifying specific groups of resistance. In the cultivar 7569, only 5.5% of the insects were able to stay longer on sustained phloem ingestion, while in the other seven cultivars these values varied from 20% to 60%. M. sacchari showed low phloem activities in cultivars 7569 and Bio266. Overall, cultivar 7569 showed the worst biological performance of aphids, with the insects presenting mechanical difficulties for feeding and a shorter duration of the phloem period, and thus being considered the most resistant. We conclude that ScYLV virus infection in different sugarcane cultivars induced specific changes in the host plant, modifying the behavior of its main vector, which may favor or impair virus transmission.