Insights into the early transcriptomic response against watermelon mosaic virus in melon.

BACKGROUND: Watermelon mosaic virus (WMV) is one of the most prevalent viruses affecting melon worldwide. Recessive resistance to WMV in melon has previously been reported in the African accession TGR-1551. Moreover, the genomic regions associated to the resistance have also been described. Nevertheless, the transcriptomic response that might infer the resistance to this potyvirus has not been explored. RESULTS: We have performed a comparative transcriptomic analysis using mock and WMV-inoculated plants of the susceptible cultivar "Bola de oro" (BO) and a resistant RIL (Recombinant inbred line) derived from the initial cross between "TGR-1551" and BO. In total, 616 genes were identified as differentially expressed and the weighted gene co-expression network analysis (WGCNA) detected 19 gene clusters (GCs), of which 7 were differentially expressed for the genotype x treatment interaction term. SNPs with a predicted high impact on the protein function were detected within the coding regions of most of the detected DEGs. Moreover, 3 and 16 DEGs were detected within the QTL regions previously described in chromosomes 11 and 5, respectively. In addition to these two specific genomic regions, we also observde large transcriptomic changes from genes spread across the genome in the resistant plants in response to the virus infection. This early response against WMV implied genes involved in plant-pathogen interaction, plant hormone signal transduction, the MAPK signaling pathway or ubiquitin mediated proteolysis, in detriment to the photosynthetic and basal metabolites pathways. Moreover, the gene MELO3C021395, which coded a mediator of RNA polymerase II transcription subunit 33A (MED33A), has been proposed as the candidate gene located on chromosome 11 conferring resistance to WMV. CONCLUSIONS: The comparative transcriptomic analysis presented here showed that, even though the resistance to WMV in TGR-1551 has a recessive nature, it triggers an active defense response at a transcriptomic level, which involves broad-spectrum resistance mechanisms. Thus, this study represents a step forward on our understanding of the mechanisms underlaying WMV resistance in melon. In addition, it sheds light into a broader topic on the mechanisms of recessive resistances.

The impact of the COVID-19 pandemic on neuropsychiatric and sleep disorders, and quality of life in individuals with neurodegenerative and demyelinating diseases: a systematic review and meta-analysis of observational studies.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has affected the mental health, sleep and quality of life, especially in individuals with chronic disease. Therefore, the purpose of this systematic review and meta-analysis was to investigate the impact of the COVID-19 pandemic on neuropsychiatric disorders (depression, anxiety, stress), sleep disorders (sleep quality, insomnia) and quality of life in individuals with Parkinson's disease (PD), Multiple Sclerosis (MS) and Alzheimer's disease (AD) compared to healthy controls. METHODS: Seven databases (Medline, Embase, ScienceDirect, Web of Science, The Cochrane Library, Scielo and Lilacs) were searched between March 2020 and December 2022. Observational studies (i.e., cross-sectional, case-control, cohort) were included. GRADE approach was used to assess the quality of evidence and strength of the recommendation. Effect size was calculated using standardized mean differences (SMD; random effects model). A customized Downs and Black checklist was used to assess the risk of bias. RESULTS: Eighteen studies (PD = 7, MS = 11) were included. A total of 627 individuals with PD (healthy controls = 857) and 3923 individuals with MS (healthy controls = 2432) were analyzed. Twelve studies (PD = 4, MS = 8) were included in the meta-analysis. Individuals with PD had significantly elevated levels of depression (very low evidence, SMD = 0.40, p = 0.04) and stress (very low evidence, SMD = 0.60, p < 0.0001). There was no difference in anxiety (p = 0.08). Individuals with MS had significantly higher levels of depression (very low evidence, SMD = 0.73, p = 0.007) and stress (low evidence, SMD = 0.69, p = 0.03) and low quality of life (very low evidence, SMD = 0.77, p = 0.006). There was no difference in anxiety (p = 0.05) and sleep quality (p = 0.13). It was not possible to synthesize evidence in individuals with AD and sleep disorder (insomnia). CONCLUSION: In general, the COVID-19 pandemic negatively impacted individuals with PD and MS. Individuals with PD showed significantly higher levels of depression and stress; and individuals with MS presented significantly higher depression and stress levels, as well as significantly lower quality of life when compared to healthy controls. Further studies are needed to investigate the impact of the COVID-19 pandemic in individuals with AD.

Serum Vitamins A and E at Mid-Pregnancy and Their Relationships with Both Maternal and Cord Blood Antioxidant Status and Perinatal Conditions: The NELA Cohort.

INTRODUCTION: Most of the pregnant women do not achieve the recommended dietary intake of vitamins A and E. These vitamins may counteract oxidative stress involved in some adverse perinatal outcomes. We aimed to assess the associations between maternal vitamin A and E at mid-pregnancy with both maternal and fetal outcomes and to identify possible early biomarkers during pregnancy to predict and prevent oxidative stress in the offspring. METHODS: Data on dietary and serum levels of vitamins A and E were collected from 544 pregnant women from the Nutrition in Early Life and Asthma (NELA) study, a prospective mother-child cohort set up in Spain. RESULTS: There were large discrepancies between low dietary vitamin E intake (78% of the mothers) and low serum vitamin E levels (3%) at 24 weeks of gestation. Maternal serum vitamins A and E at mid-pregnancy were associated with higher antioxidant status not only in the mother at this time point (lower hydroperoxides and higher total antioxidant activity [TAA]) but also with the newborn at birth (higher TAA). Gestational diabetes mellitus (GDM) was negatively associated with maternal serum vitamin A (OR: 0.95 CI: 0.91-0.99, p = 0.009) at mid-pregnancy. Nevertheless, we could not detect any association between GDM and oxidative stress parameters. CONCLUSIONS: In conclusion, maternal vitamin A and E serum levels may be used as an early potential biomarker of antioxidant status of the neonate at birth. Control of these vitamins during pregnancy could help avoid morbid conditions in the newborn caused by oxidative stress in GDM pregnancies.

MedMinas project: design and use of mixed methods in the evaluation of pharmaceutical services in primary health care in Minas Gerais, Brazil.

BACKGROUND: The main purposes of primary care-based pharmaceutical services (PHCPS) in Brazil are to provide free access to medicines and pharmaceutical care to patients. Several obstacles hinder achieving their goals; thus, MedMinas Project aimed to evaluate the PHCPS, the supply system, and the use of medicines. This paper reflects on our experience designing, planning, and conducting the project, describing the issues yielded in the field and lessons learned. METHODS: This work consists of a mixed-methods study conducted in Minas Gerais, Southeastern Brazil. We adopted the principles of Rapid Evaluation Methods, employing a multistage stratified sampling for the quantitative and a purposeful sampling for the qualitative components, respectively, and a documentary research. Data sources included individuals (patients and professionals), prescriptions, dispensed medicines, and policy documents collected between April and October 2019. The quantitative data described in this paper were analysed by descriptive statistics and the qualitative by Thematic Content Analysis. RESULTS: A total of 26 municipalities varying from 37,784 to 409,341 inhabitants were included. The field team spent, on average, 16 days in each location. We interviewed 1019 respondents, of which 127 were professionals and 892 patients. The participation rate varied from 92 to 100%, depending on the respondent subgroup. Most interviews lasted between 45 min and one hour. Fieldwork challenges included participants' enrolment, field team, interview processes, and project budget. The participants provided positive feedback and five main themes emerged from the interview experience (self-awareness, sense of gratitude, research value, access to findings, and benefits of the research). Additionally, we collected copies of 1072 documents and 2070 pieces of data from prescriptions filled and medicines dispensed at the PCP. CONCLUSION: We demonstrated the viability of conducting the MedMinas Project in an extensive geographic area within effective time frames that provided meaningful, high-quality data from multiple actors. The methods and lessons learned are valuable for researchers across various disciplines in similar urban settings in Brazil and other countries of low- and middle-income (LMIC).

Advanced Genetic Studies on Powdery Mildew Resistance in TGR-1551.

Cucurbits powdery mildew (CPM) is one of the main limiting factors of melon cultivation worldwide. Resistance to races 1, 2, and 5 has been reported in the African accession TGR-1551, whose resistance is controlled by a dominant-recessive epistasis. The dominant and recessive quantitative trail loci (QTL) have previously been located in chromosomes 5 and 12, respectively. We used several densely genotyped BC3 families derived from the cross between TGR-1551 and the susceptible cultivar 'Bola de Oro' to finely map these resistance regions. The further phenotyping and genotyping of the selected BC5, BC5S1, BC5S2, BC4S1, BC4xPS, and (BC4xPS) S1 offspring allowed for the narrowing of the candidate intervals to a 250 and 381 kb region in chromosomes 5 and 12, respectively. Moreover, the temperature effect over the resistance provided by the dominant gene has been confirmed. High resolution melting markers (HRM) were tightly linked to both resistance regions and will be useful in marker-assisted selection programs. Candidate R genes with variants between parents that caused a potential modifier impact on the protein function were identified within both intervals. These candidate genes provide targets for future functional analyses to better understand the resistance to powdery mildew in melons.

Identification of Biomarkers for Diagnosis and Prognosis of Congenital and Acute Toxoplasmosis.

BACKGROUND: The diagnosis of congenital toxoplasmosis can be inconclusive in many cases. Despite the several serological tests developed, the literature on biomarkers that can assist in the diagnosis of congenital an acute toxoplasmosis is limited. The objective of this study was to analyze the immunoreactive profile of Toxoplasma gondii protein bands with the potential to be biomarkers for diagnosis and prognosis of congenital and acute toxoplasmosis. METHODS: Peripheral blood samples from women of childbearing age and/or pregnant women diagnosed with acquired toxoplasmosis as well as from congenitally infected children were selected and submitted to immunoblotting for analysis of the immunoreactive bands profile by immunoglobulin G (IgG) antibodies. RESULTS: When comparing the immunoreactive bands profile for antibodies present in samples from different groups and subgroups, the 150, 18.5, and 16.96-kDa bands were more immunoreactive with the antibodies present in serum samples from the acquired infection group. The 343, 189, 150, 75, and 42-kDa bands showed more chance to be detected by the symptomatic congenital infection subgroup samples, while the 61, 50, and 16.96-kDa bands were significantly immunoreactive with the acute infection subgroup samples. CONCLUSIONS: The identification of these potential biomarkers can assist in early diagnosis and treatment of congenital toxoplasmosis.

Spatial distribution of Toxoplasma gondii in cows and associated risk factors.

The aim of the present study was to evaluate the spatial distribution of the prevalence of T. gondii in cows using the indirect immunofluorescence assay and determine associated risk factors. Serum samples were collected from 2970 cows on 263 rural farms in 223 municipalities. A questionnaire was administered to herd owners to collect data for the evaluation of risk factors associated with this disease. Mean seroprevalence of T. gondii in cows was 8.48% (95% CI: 7.48 to 9.49). The microregions with the greatest likelihood (p ≤ 0.05) of having infected animals were Anápolis, Ceres, São Miguel do Araguaia, the Federal District, Anicuns, and Vão do Paraná. The purchase of females or males for reproductive/breeding purposes was significantly associated (p ≤ 0.05) with the prevalence of T. gondii in these regions. A positive correlation (0.7618; p = 0.047) was found between the prevalence of T. gondii and total area in hectares of forests in these regions, suggesting that wild cats may be disseminating T. gondii at these sites. The present results highlight the importance of considering the meat from these animals to be an important infection route for humans who eat raw or undercooked food.

Melon Genome Regions Associated with TGR-1551-Derived Resistance to Cucurbit yellow stunting disorder virus.

Cucurbit yellow stunting disorder virus (CYSDV) is one of the main limiting factors of melon cultivation worldwide. To date, no commercial melon cultivars resistant to CYSDV are available. The African accession TGR-1551 is resistant to CYSDV. Two major quantitative trait loci (QTLs) have been previously reported, both located near each other in chromosome 5. With the objective of further mapping the gene or genes responsible of the resistance, a recombinant inbred line (RIL) population derived from the cross between TGR-1551 and the susceptible cultivar 'Bola de Oro' was evaluated for resistance to CYSDV in five different assays and genotyped in a genotyping by sequencing (GBS) analysis. The major effect of one of the two QTLs located on chromosome 5 was confirmed in the multienvironment RIL assay and additionally verified through the analysis of three segregating BC1S1 populations derived from three resistant RILs. Furthermore, progeny test using the offspring of selected BC3 plants allowed the narrowing of the candidate interval to a 700 kb region. The SNP markers identified in this work will be useful in marker-assisted selection in the context of introgression of CYSDV resistance in elite cultivars.

Effect of Freeze-Dried Red Beet (Beta vulgaris L.) Leaf Supplementation on Biochemical and Anthropometrical Parameters in Overweight and Obese Individuals: a Pilot Study.

Obesity is an important public health concern and is directly related with chronic noncommunicable diseases that affect the health of millions of people around the world. This study was held to verify the short-term effects related to the consumption of freeze-dried red beet leaves on biochemical and anthropometrical parameters of volunteers with overweight/obesity and dyslipidemia. Participants (n = 36) were divided at random into two groups. The control group (CG) received nutritional guidance only, and the intervention group (IG) received nutritional guidance and consumed 2.8 g of freeze-dried red beet leaves for four weeks. Biochemical tests and anthropometric measurements were collected, before and after intervention. The distribution of the characteristics between groups was similar. Parameters related to body weight and body mass index (BMI) had a significant reduction in the two groups (p = 0.05). Significant reduction on LDL-cholesterol was found only for the IG (p < 0.01). These data suggest a potential effect of consumption of red beet leaves on the health of individuals with overweight or obesity.

Anaerobic Metabolism in T4 Acanthamoeba Genotype.

Members of the genus Acanthamoeba are of the most common protozoa that has been isolated from a variety of environment and affect immunocompromised individuals, causing granulomatous amoebic encephalitis and skin lesions. Acanthamoeba, in immunocompetent patients, may cause a keratitis related to corneal microtrauma. These free-living amoebas easily adapt to the host environment and wield metabolic pathways such as the energetic and respiratory ones in order to maintain viability for long periods. The energetic metabolism of cysts and trophozoites remains mostly unknown. There are a few reports on the energetic metabolism of these organisms as they are mitochondriate eukaryotes and some studies under aerobic conditions showing that Acanthamoeba hydrolyzes glucose into pyruvate via glycolysis. The aim of this study was to detect the energetic metabolic pathways with emphasis on anaerobic metabolism in trophozoites of three isolates of Acanthamoeba sp belonging to the T4 genotype. Two samples were collected in the environment and one was a clinical sample. The evaluation of these microorganisms proceeded as follows: rupture of trophozoites (7.5 × 103 parasites/ml) and biochemical analysis with high performance liquid chromatography and spectrophotometry. The anaerobic glycolysis was identified through the detection of glucose, pyruvate, and lactate. The protein catabolism was identified through the detection of fumarate, urea, and creatinine. The fatty acid oxidation was identified through the detection of acetate, beta-hydroxybutyrate, and propionate. The detected substances are the result of the consumption of energy reserves such as glycogen and lipids. The anaerobic glycolysis and protein catabolism pathways were observed in all three isolates: one clinical and two environmental. This study represents the first report of energetic pathways used by trophozoites from different isolates of the T4 genotype Acanthamoeba.

A benzimidazole derivative (RCB20) in vitro induces an activation of energetic pathways on Taenia crassiceps (ORF strain) cysticerci.

Human cysticercosis caused by Taenia crassiceps is unusual; however, it is an useful experimental model for cysticercosis studies. Benzimidazole derivatives are important antihelminthic drugs widely used against helminths. A novel compound 6-chloro-5-(1-naphthyloxy) -2-(trifluoromethyl)-1H-benzimidazole (RCB20) is a benzimidazole derivative less polar and more lipophilic. The aim of this study was to detect the effect of the RCB20 on the in vitro energetic metabolism of T. crassiceps cysticerci. For this, products of the metabolism both produced and secreted/excreted (S/E) by the parasite were detected through spectrophotometry and high performance liquid chromatography after exposure to 6.5 and 13 µM of RCB20 and albendazole sulfoxide (ABZSO). There was a gradual increase in the concentrations of glucose not uptaken by parasites exposed to both concentrations RCB20 and ABZSO. There was a higher concentration of all the organic acids related to the tricarboxilic acid cycle int the parasites exposed to RCB20. The structural differences between RCB20 and ABZSO result in different targets within the parasite and in a greater induction of the energetic pathways, such as the glycolysis and the TCA cycle. RCB20 is a good candidate as a substitute for anthelminthic benzimidazoles due to a differentiated site of action with similar outcome.

Fruit quality assessment of watermelons grafted onto citron melon rootstock.

BACKGROUND: The grafting of watermelons (Citrullus lanatus) is a common technique that increases yield under stressful soil conditions. The most common rootstocks for watermelons are Cucurbita hybrids. However, they often have a negative impact on fruit quality. Exploiting novel Citrullus germplasm such as citron melon (Citrullus lanatus var. citroides) is an alternative to avoid these quality problems. RESULTS: Citron melon has been validated as watermelon rootstock, comparing its effects on watermelon quality to those of Cucurbita hybrids. Larger fruits with thicker rinds were observed in fruits from plants grafted onto both citron and Cucurbita rootstocks. The citron melon had no significant effect on flesh sugars or acid profiles compared to non-grafted watermelons, except for an increase in glucose and malic acid content, which also occurred in the Cucurbita rootstocks. The aroma profile of fruits produced on citron melon was similar to that of the non-grafted and self-grafted controls. The citron rootstock did not display the increased levels of (Z)-6-nonen-1-ol (a compound associated with pumpkin-like odors) found in fruits produced with Cucurbita hybrids. CONCLUSION: The low impact of citron melon rootstock on fruit quality, along with the enhanced resistance against nematodes, make the citron a promising alternative to Cucurbita rootstocks. © 2016 Society of Chemical Industry.

INFRAFRONTIER: a European resource for studying the functional basis of human disease.

Ageing research and more generally the study of the functional basis of human diseases profit enormously from the large-scale approaches and resources in mouse functional genomics: systematic targeted mutation of the mouse genome, systemic phenotyping in mouse clinics, and the archiving and distribution of the mouse resources in public repositories. INFRAFRONTIER, the European research infrastructure for the development, systemic phenotyping, archiving and distribution of mammalian models, offers access to sustainable mouse resources for biomedical research. INFRAFRONTIER promotes the global sharing of high-quality resources and data and thus contributes to data reproducibility and animal welfare. INFRAFRONTIER puts great effort into international standardisation and quality control and into technology development to improve and expand experimental protocols, reduce the use of animals in research and increase the reproducibility of results. In concert with the research community and the International Mouse Phenotyping Consortium (IMPC), INFRAFRONTIER is currently developing new pilot platforms and services for the research on ageing and age-related diseases.

Alternative energy production pathways in Taenia crassiceps cysticerci in vitro exposed to a benzimidazole derivative (RCB20).

Biochemical studies of benzimidazole derivatives are important to determine their mode of action and activity against parasites. The lack of antihelminthic alternatives to treat parasitic infections and albendazole resistance cases make the search for new antiparasitary drugs of utmost importance. The 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole (RCB20) is a benzimidazole derivative with promising effect. This study evaluated the effect of different concentrations of RCB20 in the alternative energetic pathway of in vitro Taenia crassiceps cysticerci. The parasites were in vitro exposed to 6.5 and 13 µM of RCB20 and albendazole sulfoxide (ABZSO). The quantification of acetate, acetoacetate, ß-hydroxybutyrate, fumarate and propionate was performed by high-performance liquid chromatography. The quantification of urea, creatinine and total proteins was performed by spectrophotometry. The increase in ß-hydroxybutyrate reflects the enhancement of the fatty acid oxidation in the treated groups. Volatile fatty acids secretion, acetate and propionate, was increased in the treated groups. The secretion mechanisms of the treated parasites were impaired due to organic acids increased concentrations in the cysticerci. It is possible to conclude that the metabolic effect on alternative energetic pathways is slightly increased in the parasites treated with RCB20 than the ones treated with ABZSO.

Quantifying efficacy and limits of unmanned aerial vehicle (UAV) technology for weed seedling detection as affected by sensor resolution.

In order to optimize the application of herbicides in weed-crop systems, accurate and timely weed maps of the crop-field are required. In this context, this investigation quantified the efficacy and limitations of remote images collected with an unmanned aerial vehicle (UAV) for early detection of weed seedlings. The ability to discriminate weeds was significantly affected by the imagery spectral (type of camera), spatial (flight altitude) and temporal (the date of the study) resolutions. The colour-infrared images captured at 40 m and 50 days after sowing (date 2), when plants had 5-6 true leaves, had the highest weed detection accuracy (up to 91%). At this flight altitude, the images captured before date 2 had slightly better results than the images captured later. However, this trend changed in the visible-light images captured at 60 m and higher, which had notably better results on date 3 (57 days after sowing) because of the larger size of the weed plants. Our results showed the requirements on spectral and spatial resolutions needed to generate a suitable weed map early in the growing season, as well as the best moment for the UAV image acquisition, with the ultimate objective of applying site-specific weed management operations.

Delusions and the role of beliefs in perceptual inference.

Delusions are unfounded yet tenacious beliefs and a symptom of psychotic disorder. Varying degrees of delusional ideation are also found in the healthy population. Here, we empirically validated a neurocognitive model that explains both the formation and the persistence of delusional beliefs in terms of altered perceptual inference. In a combined behavioral and functional neuroimaging study in healthy participants, we used ambiguous visual stimulation to probe the relationship between delusion-proneness and the effect of learned predictions on perception. Delusional ideation was associated with less perceptual stability, but a stronger belief-induced bias on perception, paralleled by enhanced functional connectivity between frontal areas that encoded beliefs and sensory areas that encoded perception. These findings suggest that weakened lower-level predictions that result in perceptual instability are implicated in the emergence of delusional beliefs. In contrast, stronger higher-level predictions that sculpt perception into conformity with beliefs might contribute to the tenacious persistence of delusional beliefs.

Pretreatment anterior cingulate activity predicts antidepressant treatment response in major depressive episodes.

Major depressive disorder leads to substantial individual and socioeconomic costs. Despite the ongoing efforts to improve the treatment for this condition, a trial-and-error approach until an individually effective treatment is established still dominates clinical practice. Searching for clinically useful treatment response predictors is one of the most promising strategies to change this quandary therapeutic situation. This study evaluated the predictive value of a biological and a clinical predictor, as well as a combination of both. Pretreatment EEGs of 31 patients with a major depressive episode were analyzed with neuroelectric brain imaging technique to assess cerebral oscillations related to treatment response. Early improvement of symptoms served as a clinical predictor. Treatment response was assessed after 4 weeks of antidepressant treatment. Responders showed more slow-frequency power in the right anterior cingulate cortex compared to non-responders. Slow-frequency power in this region was found to predict response with good sensitivity (82 %) and specificity (100 %), while early improvement showed lower accuracy (73 % sensitivity and 65 % specificity). Combining both parameters did not further improve predictive accuracy. Pretreatment activity within the anterior cingulate cortex is related to antidepressive treatment response. Our results support the search for biological treatment response predictors using electric brain activity. This technique is advantageous due to its low individual and socioeconomic burden. The benefits of combining both, a clinically and a biologically based predictor, should be further evaluated using larger sample sizes.

[Evaluation of the Sysmex UF-1000i flow cytometer for screening of urinary tract infection]. / Evaluación del citómetro UF-1000i como método de cribado en el diagnóstico de infecciones del tracto urinario.

INTRODUCTION: The urine culture is a huge workload in the Microbiology Laboratory and remains the gold standard for the diagnosis of urinary tract infections. Considering the high prevalence of negative results, the implementation of a reliable screening method could lead to cost saving in the workload, and speed up reporting of negative results. METHODS: We evaluated the usefulness of the flow cytometer UF-1000i in the screening for negative samples than could be excluded from culture. We divided the samples into two groups, Group 1, males and women of childbearing age who were considered positive with a growth ≥ 104 CFU/ml, and Group 2, considered positive with ≥ 105 CFU/ml growth. RESULTS: On comparing the culture and screening data in the ROC curve, the best sensitivity and specificity points were 53.1 bact/µl for Group 1, and 128.3 bact/µl for Group 2. In Group 1, the sensitivity was 92.2% and a specificity of 60%, a reduction in urine cultures of 46%, with 2.1% false negative (42 samples). In Group 2, the sensitivity was 86%, with a specificity of 87.7%, a culture reduction of 57.5%, and 5.1% false negatives (74 samples). CONCLUSION: The incorporating of the UF-1000i cytometer to the screening of urine samples depends on the characteristics of the patients and the definition of positive urine culture. In our case, with only studying bacteriuria, the data on the reduction of workload and the false negatives seriously question this incorporation.

A novel automated alternating current biosusceptometry method to characterization of controlled-release magnetic floating tablets of metronidazole.

CONTEXT: Alternating Current Biosusceptometry is a magnetically method used to characterize drug delivery systems. This work presents a system composed by an automated ACB sensor to acquire magnetic images of floating tablets. OBJECTIVE: The purpose of this study was to use an automated Alternating Current Biosusceptometry (ACB) to characterize magnetic floating tablets for controlled drug delivery. MATERIALS AND METHODS: Floating tablets were prepared with hydroxypropyl methylcellulose (HPMC) as hydrophilic gel material, sodium bicarbonate as gas-generating agent and ferrite as magnetic marker. ACB was used to characterize the floating lag time and the tablet hydration rate, by quantification of the magnetic images to magnetic area. Besides the buoyancy, the floating tablets were evaluated for weight uniformity, hardness, swelling and in vitro drug release. RESULTS: The optimized tablets were prepared with equal amounts of HPMC and ferrite, and began to float within 4 min, maintaining the flotation during more than 24 h. The data of all physical parameters lied within the pharmacopeial limits. Drug release at 24 h was about 40%. CONCLUSIONS: The ACB results showed that this study provided a new approach for in vitro investigation of controlled-release dosage forms. Moreover, using automated ACB will also be possible to test these parameters in humans allowing to establish an in vitro.in vivo correlation (IVIVC).

Genomic Insights into Staphylococcus aureus Isolates Exhibiting Diminished Daptomycin Susceptibility.

Daptomycin is one of the last therapeutic resources for multidrug-resistant gram-positive bacteria. Despite its structural similarities with glycopeptides, its mechanisms of action and resistance are different and in some respects are not completely understood. Mutations in several genes have been associated with daptomycin resistance, especially in mprF, walkR, rpoB and rpoC, but their role and importance remain to be elucidated. We have studied mutations in 11 genes, which have been previously associated with daptomycin non-susceptibility, in nine daptomycin-non-susceptible Staphylococcus aureus clinical isolates (daptomycin MIC: >1 mg/L). Susceptibility to daptomycin, vancomycin, linezolid, oxacillin, telavancin and dalbavancin was studied. walkR, agrA, cls1, cls2, fakA, pnpA, clpP, prs, rpoB, rpoC and mprF were amplified by PCR and sequenced. The sequences were compared with the S. aureus ATCC 25923 complete genome (GenBank gi: 685631213) by using BLAST® software. We did not find any changes in walkR, pnpA, prs and clpP. All isolates excepting isolate MSa5 showed a high number of significant mutations (between 13 and 25 amino acid changes) in mprF. Most isolates also showed mutations in the rpo genes, the cls genes and fakA. Daptomycin non-susceptibility in S. aureus clinical isolates seems to be reached through different mutation combinations when compared to S. aureus ATCC 25293. Especially mprF and cls1 showed very high polymorphism in most isolates. Meanwhile, one isolate, MSa5, showed only single mutation in mprF (P314T).