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45 result(s) for "Petersen, Vivian"
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The toolbox for mosquito vector research
The work of collecting mosquitoes in the field is essential for improving knowledge about species of known and unknown vector status, their invasion dynamics, and further understanding their involvement in circulating pathogens of medical and veterinary importance. Over the years, different techniques have been developed to capture mosquitoes for entomological, pathogen transmission, and surveillance studies. For entomological and transmission dynamic research to be reliable, it is essential for mosquito specimens to be correctly identified so that their role in pathogen transmission can be appropriately assessed. Currently, modern molecular techniques support traditional morphological taxonomic identification and provide faster and more assertive identification. It is also important to test the susceptibility of potentially relevant mosquitoes or mosquitoes with unknown vector status in the laboratory to identify which species could participate in pathogen transmission. This last step toward fully performing vector incrimination of mosquito species and understanding their interactions with relevant pathogens requires proper handling of live specimens and laboratory colonization under artificial conditions to perform artificial infection studies. In this work, we aim to underscore the significance of the available tools for entomological studies and pathogen transmission research while also offering insights into the principles behind recent technological advancements that enhance the effectiveness and reliability of these studies. Graphical Abstract
Investigating the safety of photobiomodulation in oral carcinogenesis: insights into cell proliferation, invasion, and apoptosis via the 4NQO model
The present investigation aimed to assess the safety of photobiomodulation (PBM) on the oral carcinogenesis process induced by 4NQO, focusing on cell proliferation and apoptosis. Sixty-six Wistar rats received systemic 4NQO for 12 ( n  = 33) and 20 weeks ( n  = 33), divided into Control group, PBM 0.3 J, and PBM 1 J. Applications for PBM occurred three times a week. At weeks 12 and 20, the animals were euthanized. The immunoreactivity for anti-ROS1 and anti-p53 antibodies was also assessed. Statistical analysis was assessed by multiple t-tests, Kruskal-Wallis, and Spearman’s correlation. At 12 weeks, PBM 1 J group had nodular lesions, distinct from control and PBM 0.3 J groups ( p  = 0.005). At 20 weeks, nodular lesions were common in control and PBM 0.3 J groups. Histopathological characteristics did not significantly differ between groups at 12 ( p  = 0.30) and 20 weeks ( p  = 0.58). Epithelial dysplasia ( n  = 21) was common at 12 weeks. After 20 weeks, most of the cases revealed squamous cell carcinoma ( n  = 24). No differences were observed in the immunostaining of p53 and ROS1 among the control and experimental groups and there was no correlation of these proteins with clinicopathological data. During the carcinogenesis process, the PBM did not modify the development of oral lesions and the expression of proliferative and apoptosis proteins.
Photobiomodulation therapy modulates epigenetic events and NF-κB expression in oral epithelial wound healing
The aim of this study was to evaluate the effect of photobiomodulation therapy (PBMT) on histone 3 acetylation (acH3) and NF-κB expression during oral ulcer healing. A total of 48 male Wistar rats were divided into control group (CG) and PBMT group (n = 24 each). Traumatic ulcers were created in the dorsum of the rats’ tongue with a punch tool. Irradiation with InGaAlP laser, 660 nm, 40 mW, 0.04 cm2 spot size, 4 J/cm2, 4 s, and 0.16 J per spot was performed once a day in close contact for 10 consecutive days. CG received only daily handling. Rats were euthanized on days 3, 5, and 10 (n = 8) and were monitored daily to assess wound status. Immunohistochemical analysis for acH3 and NF-κB detection was performed. One thousand epithelial cells were counted, and mean acH3- and NF-κB-positive cells were calculated and compared between the groups. PBMT accelerated the repair of oral ulcers. On day 3, PBMT showed significantly higher means for acH3- and NF-κB-positive cells than CG. On day 5, no difference was observed between the groups concerning both markers. On day 10, PBMT presented lower acH3 and NF-κB means than the control group. We concluded that PBMT stimulates keratinocyte migration in the early stage of oral wound healing and keratinocyte differentiation at the final stage by modulating histone acetylation and NF-κB expression.
First report of naturally infected Aedes aegypti with chikungunya virus genotype ECSA in the Americas
The worldwide expansion of new emergent arboviruses such as Chikungunya and Zika reinforces the importance in understanding the role of mosquito species in spreading these pathogens in affected regions. This knowledge is essential for developing effective programs based on species specificity to avoid the establishment of endemic transmission cycles sustained by the identified local vectors. Although the first autochthonous transmission of Chikungunya virus was described in 2014 in the north of Brazil, the main outbreaks were reported in 2015 and 2016 in the northeast of Brazil. During 5 days of February 2016, we collected mosquitoes in homes of 6 neighborhoods of Aracaju city, the capital of Sergipe state. Four mosquito species were identified but Culex quinquefasciatus and Aedes aegypti were the most abundant. Field-caught mosquitoes were tested for Chikungunya (CHIKV), Zika (ZIKV) and Dengue viruses (DENV) by qRT-PCR and one CHIKV-infected Ae. aegypti female was detected. The complete sequence of CHIKV genome was obtained from this sample and phylogenetic analysis revealed that this isolate belongs to the East-Central-South-African (ECSA) genotype. Our study describes the first identification of a naturally CHIKV-infected Ae. aegypti in Brazil and the first report of a CHIKV from ECSA genotype identified in this species in the Americas. These findings support the notion of Ae. aegypti being a vector involved in CHIKV outbreaks in northeast of Brazil.
Transgene-induced cell death following dengue-2 virus infection in Aedes aegypti
Dengue viruses (DENVs) are mosquito-borne flaviviruses causing millions of human infections each year and pose a challenge for public health systems worldwide. Aedes aegypti is the principal vector species transmitting DENVs to humans. Controlling Ae. aegypti is difficult due to the abundance of breeding sites and increasing insecticide resistance in the vector populations. Developing new vector control strategies is critical for decreasing the disease burden. One potential approach is genetically replacing Ae. aegypti populations with vector populations highly resistant to DENV transmission. Here, we focus on an alternative strategy for generating dengue 2 virus (DENV-2) resistance in genetically-modified Ae. aegypti in which the mosquitoes express an inactive form of Michelob_x (Mx), an antagonist of the Inhibitor of Apoptosis (IAP), to induce apoptosis in those cells in which actively replicating DENV-2 is present. The inactive form of Mx was flanked by the RRRRSAG cleavage motif, which was recognized by the NS2B/NS3 protease of the infecting DENV-2 thereby releasing and activating Mx which then induced apoptosis. Our transgenic strain exhibited a significantly higher mortality rate than the non-transgenic control when infected with DENV-2. We also transfected a DNA construct containing inactive Mx fused to eGFP into C6/36 mosquito cells and indirectly observed Mx activation on days 3 and 6 post-DENV-2 infections. There were clear signs that the viral NS2B/NS3 protease cleaved the transgene, thereby releasing Mx protein into the cytoplasm, as was confirmed by the detection of eGFP expression in infected cells. The present study represents proof of the concept that virus infection can be used to induce apoptosis in infected mosquito cells.
Photobiomodulation regulates cytokine release and new blood vessel formation during oral wound healing in rats
The aim of the present study was to evaluate the effects of photobiomodulation (PBM) on cytokine levels and angiogenesis during oral wound healing. Ulcers were made on the dorsum of the tongue in 48 Wistar rats. Irradiation with an indium-gallium-aluminum-phosphide (InGaAlP) laser (660 nm; output power, 40 mW; spot size, 0.04 cm 2 ) was performed once a day on two points of the ulcer for 14 days. Two different energy densities were used: 4 J/cm 2 (energy per point 0.16 J, total energy 0.32 J) and 20 J/cm 2 (energy per point 0.8 J, total energy 1.6 J). Tissue levels of interleukin (IL)-1β and tumor necrosis factor (TNF)-α were investigated by enzyme-linked immunosorbent assay (ELISA). Image analysis of CD31-immunostained sections was used to investigate microvessel density (MVD). PBM increased the tissue levels of IL-1β at the early stage of oral wound healing ( p  < 0.01) and increased the tissue levels of TNF-α during all stages of oral wound healing ( p  < 0.05). PBM at a dose of 4 J/cm 2 produced more significant results regarding cytokine modulation and was associated with higher MVD at day 5. Collectively, these findings indicate that cytokine modulation and increased angiogenesis are among the basic mechanisms whereby PBM improves oral wound repair.
Aedes (Ochlerotatus) scapularis, Aedes japonicus japonicus, and Aedes (Fredwardsius) vittatus (Diptera: Culicidae): Three Neglected Mosquitoes with Potential Global Health Risks
More than 3550 species of mosquitoes are known worldwide, and only a fraction is involved in the transmission of arboviruses. Mosquitoes in sylvatic and semi-sylvatic habitats may rapidly adapt to urban parks and metropolitan environments, increasing human contact. Many of these mosquitoes have been found naturally infected with arboviruses from the Alphaviridae, Flaviviridae, and Bunyaviridae families, with many being the cause of medically important diseases. However, there is a gap in knowledge about the vector status of newly invasive species and their potential threat to human and domestic animal populations. Due to their rapid distribution, adaptation to urban environments, and anthropophilic habits, some neglected mosquito species may deserve more attention regarding their role as secondary vectors. Taking these factors into account, we focus here on Aedes (Ochlerotatus) scapularis (Rondani), Aedes japonicus japonicus (Theobald), and Aedes (Fredwardsius) vittatus (Bigot) as species that have the potential to become important disease vectors. We further discuss the importance of these neglected mosquitoes and how factors such as urbanization, climate change, and globalization profoundly alter the dynamics of disease transmission and may increase the participation of neglected species in propagating diseases.
High morphological and genetic variabilities of Ochlerotatus scapularis, a potential vector of filarias and arboviruses
BACKGROUND: Ochlerotatus scapularis is a potential vector of filarias and arboviruses in the Neotropics. This species was once typically associated with sylvatic environments; however, cases of synanthropy and urbanization of this species have been increasingly reported in southeast Brazil. Despite the medical relevance of Oc. scapularis, its populational variability is not yet known. To our knowledge, this is the first report describing the morphological and genetic variabilities of this species. METHODS: Population samples were characterized using the cytochrome oxidase subunit I (COI) mitochondrial gene and wing geometrics. Adult mosquitoes were collected from five sampling sites from remnants of the Atlantic forest embedded in the urban or rural areas of southeast Brazil. RESULTS: In the 130 individuals analyzed, 46 COI haplotypes were detected. Haplotype diversity was high and ranged from 0.66 to 0.97. Six haplotypes were present in 61% of the individuals, whereas the remaining haplotypes were less frequent (39%). Wing shape was also highly polymorphic. Differentiation of populations across sampling sites according to genetic distances (Fₛₜ = −0.009 to 0.060) and morphological distances (Qₛₜ = 0.47) indicated that populations were not identical. No correlations were noted for phenetic and genetic diversities (p = 0.19) or for genetic or phenetic distances with geographical distances (p = 0.2 and p = 0.18, respectively). CONCLUSIONS: Our study results suggest that Oc. scapularis has a rich genetic patrimony, even though its habitat is fragmented. Implications of such genetic richness with respect to vectorial competence, plasticity, and ability to exploit urbanized areas need to be further investigated.
Assessment of the correlation between wing size and body weight in captive Culex quinquefasciatus
Mass production of mosquitoes under laboratory conditions allows implementing methods to control vector mosquitoes. Colony development depends on mosquito size and weight. Body size can be estimated from its correlation with wing size, whereas weight is more difficult to determine. Our goal was to test whether wing size can predict the weight. We compared dry weight and wing centroid size of Culex quinquefasciatus reared at different temperatures and four diets. Weight and wing size were strongly correlated. The diets did not influence wing size. Wing centroid size is a good predictor of Cx. quinquefasciatus body weight.
Expression of DNMTs and H3K9ac in Ameloblastoma and Ameloblastic Carcinoma
Objectives: DNA methyltransferases (DNMTs) and the histone modification H3K9ac are epigenetic markers. This study aimed to describe the immunohistochemical expression of DNMT1, DNMT3A, DNMT3B, and H3K9ac in the dental follicle (DF), ameloblastoma (AME), and ameloblastic carcinoma (AC), correlating these expressions with the recurrence and aggressive behavior in ameloblastoma. Study Design: Immunohistochemical reactions were performed in 10 human DFs, 38 ameloblastomas, and 6 AC samples. Another 59 ameloblastomas assembled in a tissue microarray were used to compare the immunoexpression with the clinical, radiographic, and histopathological characteristics and the presence of BRAFv600e mutation. Each slide was digitized as a high-resolution image and quantified by Aperio ScanScope Nuclear V9 software. All statistical analyzes were performed using GraphPad Prism statistical software. Results: DNMT3B expression was higher in ameloblastomas than in the DFs, while the AC overexpressed all proteins. The ameloblastomas with BRAFv600e mutation, vestibular/lingual, or vestibular/palatine bone cortical disruption and maxilla involvement showed DNMT1 overexpression, while recurrent cases had high DNMT3B levels. Conclusions: DNA methylation and histone modification might play a role in the development, clinical aggressiveness, and recurrence rates of ameloblastoma, such as the progression to AC. Further investigation about gene methylations in ameloblastomas is needed to better understand its relationship with aggressiveness and recurrence.