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1.
Prep Biochem Biotechnol ; 53(7): 860-871, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36527445

RESUMO

Azo dyes have been found in wastewater from textile industries. These compounds continuously persist in the environment for long periods of time and may be toxic for living beings. An alternative treatment for dye removal that has proven to be effective is aerobic treatment with fungi. In this study, Aspergillus niger was investigated as a mechanism to remove orange G (OG). Removal of 200 mg/L of OG by A. niger biomass was carried out in solid and liquid medium, which showed a positive correlation between A. niger growth and dye removal. In liquid media what was proved is that the efficiency of OG removal by A. niger depends on its concentration; at 200 mg/L of OG remove by degradation and at 400 mg/L by processes as sorption and degradation. During OG removal, the generation of organic acids by A. niger was modified compared to constitutive generation, one of the modifications was the increase of gluconic acid production and the decrease of acids involved in the Krebs cycle, as well as the null detection of oxalic acid. The monitoring of organic acids by high-performance liquid chromatography (HPLC) was important because some of them have been linked to dye removal.


Assuntos
Aspergillus niger , Compostos Azo , Aspergillus niger/metabolismo , Compostos Azo/metabolismo , Águas Residuárias , Corantes/metabolismo
2.
Inorg Chem ; 61(3): 1377-1384, 2022 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-35015526

RESUMO

A new Y-based metal-organic framework (MOF) GR-MOF-6 with a chemical formula of {[YL(DMF)2]·(DMF)}n {H3L = 5-[(4-carboxyphenyl)ethynyl] isophthalic acid; DMF = N,N-dimethylformamide} has been prepared by a solvothermal route. Structural characterization reveals that this novel material is a three-dimensional MOF in which the coordination of the tritopic ligand to Y(III) metal ions leads to an intercrossing channel system extending over three dimensions. This material has proven to be a very efficient catalyst in the cyanosilylation of carbonyls, ranking second in catalytic activity among the reported rare earth metal-based MOFs described so far but with the lowest required catalyst loading. In addition, its electrophoretic behavior has been studied in depth, providing a zero-charge point between pH 4 and 5, a peak electrophoretic mobility of -1.553 µm cm V-1 s-1, and a ζ potential of -19.8 mV at pH 10.

3.
Int J Mol Sci ; 23(7)2022 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-35408957

RESUMO

Extracytoplasmic function (ECF) sigma factors are subunits of the RNA polymerase specialized in activating the transcription of a subset of genes responding to a specific environmental condition. The signal-transduction pathways where they participate can be activated by diverse mechanisms. The most common mechanism involves the action of a membrane-bound anti-sigma factor, which sequesters the ECF sigma factor, and releases it after the stimulus is sensed. However, despite most of these systems following this canonical regulation, there are many ECF sigma factors exhibiting a non-canonical regulatory mechanism. In this review, we aim to provide an updated and comprehensive view of the different activation mechanisms known for non-canonical ECF sigma factors, detailing their inclusion to the different phylogenetic groups and describing the mechanisms of regulation of some of their representative members such as EcfG from Rhodobacter sphaeroides, showing a partner-switch mechanism; EcfP from Vibrio parahaemolyticus, with a phosphorylation-dependent mechanism; or CorE from Myxococcus xanthus, regulated by a metal-sensing C-terminal extension.


Assuntos
Regulação Bacteriana da Expressão Gênica , Fator sigma , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , RNA Polimerases Dirigidas por DNA/genética , RNA Polimerases Dirigidas por DNA/metabolismo , Filogenia , Fator sigma/genética , Fator sigma/metabolismo
4.
J Am Chem Soc ; 143(48): 20071-20076, 2021 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-34797634

RESUMO

Here we report that chiral Mn(I) complexes are capable of H-P bond activation. This activation mode enables a general method for the hydrophosphination of internal and terminal α,ß-unsaturated nitriles. Metal-ligand cooperation, a strategy previously not considered for catalytic H-P bond activation, is at the base of the mechanistic action of the Mn(I)-based catalyst. Our computational studies support a stepwise mechanism for the hydrophosphination and provide insight into the origin of the enantioselectivity.

5.
Mol Microbiol ; 112(2): 385-398, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31187912

RESUMO

In order to survive, bacteria must adapt to multiple fluctuations in their environment, including coping with changes in metal concentrations. Many metals are essential for viability, since they act as cofactors of indispensable enzymes. But on the other hand, they are potentially toxic because they generate reactive oxygen species or displace other metals from proteins, turning them inactive. This dual effect of metals forces cells to maintain homeostasis using a variety of systems to import and export them. These systems are usually inducible, and their expression is regulated by metal sensors and signal-transduction mechanisms, one of which is mediated by extracytoplasmic function (ECF) sigma factors. In this review, we have focused on the metal-responsive ECF sigma factors, several of which are activated by iron depletion (FecI, FpvI and PvdS), while others are activated by excess of metals such as nickel and cobalt (CnrH), copper (CarQ and CorE) or cadmium and zinc (CorE2). We focus particularly on their physiological roles, mechanisms of action and signal transduction pathways.


Assuntos
Bactérias/metabolismo , Proteínas de Bactérias/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Metais/metabolismo , Fator sigma/metabolismo , Bactérias/enzimologia , Bactérias/genética , Proteínas de Bactérias/genética , RNA Polimerases Dirigidas por DNA/genética , Regulação Bacteriana da Expressão Gênica , Fator sigma/genética
6.
Chemistry ; 26(68): 15843-15846, 2020 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-32960476

RESUMO

Two-step dearomative functionalization of naphthols promoted by Lewis acids and copper(I) catalysis was developed. Initially, Lewis acid complexation inverted the electronic properties of the ring and established an equilibrium with the dearomatized counterpart. Subsequent trapping of the dearomatized intermediate with organometallics as well as organophosphines was demonstrated and provided the corresponding dearomatized products.

7.
Prep Biochem Biotechnol ; 50(6): 607-618, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32013716

RESUMO

In this study, the effects of Aspergillus niger in coculture with the basidiomycetes, Trametes versicolor, T. maxima, and Ganoderma spp., were studied to assess H2O2 production and laccase (Lac), Lignin Peroxidase (LiP), and manganese peroxidase (MnP) activities. The results indicated that maximum discoloration was of 97%, in the T. maxima and A. niger coculture, where the concentration of H2O2 was 5 mg/L and 6.3 mg/L in cultures without and with dye, respectively. These concentrations of H2O2 were 1.6- and 1.8-fold higher than monocultures of T. maxima (3.37 mg/L) and A. niger (3.87 mg/L), respectively. In the same coculture, the LiP and MnP enzyme activities also increased 12-fold, (from 0.08 U/mg to 0.99 U/mg), and 67-fold, (from 0.11 U/mg to 7.4 U/mg), respectively. The Lac activity increased 1.7-fold (from 13.46 U/mg to 24 U/mg). Further, a Box-Behnken experimental design indicated a 1.8-fold increase of MnP activity (from 7.4 U/mg to 13.3 U/mg). In addition, dye discoloration regression model obtained from the Box-Behnken experimental design showed a positively correlation with H2O2, (R2 = 0.58) and a negatively correlation with Lac activity (R2 = -0.7).


Assuntos
Aspergillus niger/enzimologia , Compostos Azo/metabolismo , Corantes/metabolismo , Ganoderma/enzimologia , Peróxido de Hidrogênio/metabolismo , Lacase/metabolismo , Peroxidases/metabolismo , Polyporaceae/enzimologia , Compostos Azo/química , Técnicas de Cocultura , Corantes/química , Meios de Cultura , Lignina/metabolismo
8.
Molecules ; 25(20)2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33053734

RESUMO

In addition to their own antioxidants, human cells feed on external antioxidants, such as the phenolic compounds of fruits and vegetables, which work together to keep oxidative stress in check. Sechium edule, an edible species of chayote, has phenolic compounds with antioxidant activity and antineoplastic activity. A Sechium hybrid shows one thousand times greater antineoplastic activity than edible species, but its antioxidant and anti-inflammatory activities and the content of phenolic compounds are unknown. The aim of this study was to determine the antioxidant and anti-inflammatory capacity of the extract of fruits of the Sechium hybrid in vitro and in vivo. Phytochemical analysis using HPLC showed that the extract of the Sechium hybrid has at least 16 phenolic compounds; galangin, naringenin, phloretin and chlorogenic acid are the most abundant. In an in vitro assay, this extract inhibited 2,2-diphenyl-L-picrylhydrazyl (DPPH) activity and protected the dimyristoylphosphatidylethanolamine (DMPE) phospholipid model cell membrane from oxidation mediated by hypochlorous acid (HClO). In vivo, it was identified that the most abundant metabolites in the extract enter the bloodstream of the treated mice. On the other hand, the extract reduces the levels of tumor necrosis factor alpha (TNFα), interferon gamma (IFNγ), and interleukin-6 (IL-6) but increases interleukin-10 (IL-10) and glutathione peroxidase levels. Our findings indicate that intake of the fruits of the Sechium hybrid leads to antioxidant and anti-inflammatory effects in a mouse model. Therefore, these results support the possibility of exploring the clinical effect of this hybrid in humans.


Assuntos
Antioxidantes/química , Frutas/química , Interleucina-10/química , Fator de Necrose Tumoral alfa/química , Animais , Compostos de Bifenilo/química , Glutationa Peroxidase/química , Humanos , Interferon gama/metabolismo , Interleucina-6/metabolismo , Camundongos , Fosfatidiletanolaminas/química , Picratos/química , Extratos Vegetais/química
9.
J Sleep Res ; 28(1): e12753, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30198095

RESUMO

It is often stated that sleep deprivation is on the rise, with work suggested as a main cause. However, the evidence for increasing sleep deprivation comes from surveys using habitual sleep questions. An alternative source of information regarding sleep behaviour is time-use studies. This paper investigates changes in sleep time in the UK using the two British time-use studies that allow measuring "time in bed not asleep" separately from "actual sleep time". Based upon the studies presented here, people in the UK sleep today 43 min more than they did in the 1970s because they go to bed earlier (~30 min) and they wake up later (~15 min). The change in sleep duration is driven by night sleep and it is homogeneously distributed across the week. The former results apply to men and women alike, and to individuals of all ages and employment status, including employed individuals, the presumed major victims of the sleep deprivation epidemic and the 24/7 society. In fact, employed individuals have experienced a reduction in short sleeping of almost 4 percentage points, from 14.9% to 11.0%. There has also been a reduction of 15 percentage points in the amount of conflict between workers work time and their sleep time, as measured by the proportion of workers that do some work within their "ideal sleep window" (as defined by their own chronotype).


Assuntos
Distúrbios do Início e da Manutenção do Sono/epidemiologia , Sono/fisiologia , Feminino , História do Século XX , História do Século XXI , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Fatores de Tempo , Reino Unido
10.
Nucleic Acids Res ; 44(12): 5571-84, 2016 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-26951374

RESUMO

Extracytoplasmic function sigma factors represent the third pillar of signal-transduction mechanisms in bacteria. The variety of stimuli they recognize and mechanisms of action they use have allowed their classification into more than 50 groups. We have characterized CorE2 from Myxococcus xanthus, which belongs to group ECF44 and upregulates the expression of two genes when it is activated by cadmium and zinc. Sigma factors of this group contain a Cys-rich domain (CRD) at the C terminus which is essential for detecting metals. Point mutations at the six Cys residues of the CRD have revealed the contribution of each residue to CorE2 activity. Some of them are essential, while others are either dispensable or their mutations only slightly affect the activity of the protein. However, importantly, mutation of Cys174 completely shifts the specificity of CorE2 from cadmium to copper, indicating that the Cys arrangement of the CRD determines the metal specificity. Moreover, the conserved CxC motif located between the σ2 domain and the σ4.2 region has also been found to be essential for activity. The results presented here contribute to our understanding of the mechanism of action of metal-dependent sigma factors and help to define new common features of the members of this group of regulators.


Assuntos
Proteínas de Bactérias/genética , Myxococcus xanthus/genética , Fator sigma/genética , Transativadores/genética , Transcrição Gênica , Cádmio/metabolismo , Cobre/metabolismo , Cisteína/genética , Regulação Bacteriana da Expressão Gênica/genética , Mutação , Myxococcus xanthus/metabolismo , Regiões Promotoras Genéticas , Fator sigma/metabolismo , Zinco/metabolismo
11.
J Manipulative Physiol Ther ; 41(7): 551-560, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30442354

RESUMO

OBJECTIVE: The purpose of the current randomized clinical trial was to examine the effects of cervical thrust manipulation or sham manipulation on cervicocephalic kinaesthetic sense, pain, pain-related disability, and pressure pain sensitivity in patients with mechanical neck pain. METHODS: Fifty-four individuals with neck pain were randomly assigned to receive either a cervical manipulation (right or left) or a sham manipulation. Immediate outcomes included cervical kinesthetic sense as assessed by joint position sense error (JPSE) and pressure pain thresholds (PPTs). At 1 week, neck pain intensity (numerical pain rate scale) and neck pain-related disability (Neck Disability Index [NDI]) outcomes were also collected. RESULTS: The mixed-model analysis of covariance revealed a significant group × time interaction in favor of the cervical thrust manipulation group for the JPSE on rotation and extension. There was also a significant interaction for changes in PPTs at C5 to C6 and tibialis anterior. At the 1-week follow-up, a significant interaction existed for neck-related disability but not for neck pain at rest, worst pain, or lowest pain experienced the preceding week. CONCLUSIONS: Our results suggest that cervical spine thrust manipulation improves JPSE, PPT and NDI in participants with chronic mechanical neck pain. Furthermore, changes in JPSE and NDI were large and surpass published minimal detectable changes for these outcome measures. In addition, the effect sizes of PPTs were medium; however, only C5 to C6 zygapophyseal joint exceeded the minimal detectable change. In contrast, cervical thrust manipulation did not improve neck pain intensity at 1 week after the intervention.


Assuntos
Manipulação da Coluna/métodos , Cervicalgia/terapia , Adulto , Avaliação da Deficiência , Feminino , Humanos , Cinestesia , Masculino , Medição da Dor , Limiar da Dor , Método Simples-Cego
12.
Pharm Biol ; 55(1): 1638-1645, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28427292

RESUMO

CONTEXT: Sechium edule (Jacq.) Sw. (Cucurbitaceae) is used in ethnomedicine, but the diversity of the varietal groups of this species has not often been considered. This is important because we previously reported that different variety of species exhibit different activities across different tumor cell lines. OBJECTIVE: This study investigates the chemical composition and biological activities of extracts obtained from S. edule var. nigrum spinosum. MATERIALS AND METHODS: The leukemia P388 cell line and mononuclear bone marrow cells (MNCBMs) were treated with the extract at a concentration ranging from 40 to 2370 µg/mL for cytotoxicity and viability assays. CD-1 mice were treated with 8-5000 mg/kg extract and monitored every hour for the first 24 h and subsequently for seven days for signs of toxicity (LD50). In addition, the chromatographic profile of the extract was determined by HPLC. RESULTS: The extract inhibits the proliferation of both P388 cells and MNCBMs, with IC50 values of 927 and 1911 µg/mL, respectively, but reduced the viability and induced the apoptosis of only leukemia cells. The LD50 was higher than 5000 mg/kg, and this concentration did not alter the blood chemistry or cell count but doubled the mitotic index in the bone marrow. The HPLC showed the presence of cucurbitacins, phloridzin, naringenin, phloretin, apigenin, and gallic, chlorogenic, vanillic, p-hydroxybenzoic, caffeic, and p-coumaric acids. DISCUSSION AND CONCLUSION: Sechium edule var. nigrum spinosum contains bioactive compounds that explain the antiproliferative and nutraceutical activities, and its lack of physiological side effects constitutes an added value to a widely consumed vegetable.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Cucurbitaceae/química , Leucemia P388/tratamento farmacológico , Extratos Vegetais/farmacologia , Animais , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/toxicidade , Apoptose/efeitos dos fármacos , Células da Medula Óssea/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão/métodos , Relação Dose-Resposta a Droga , Feminino , Frutas , Concentração Inibidora 50 , Dose Letal Mediana , Leucemia P388/patologia , Masculino , Metanol/química , Camundongos , Extratos Vegetais/administração & dosagem , Extratos Vegetais/toxicidade
13.
Environ Microbiol ; 18(3): 766-79, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26663201

RESUMO

The first documented study on bacterial predation was carried out using myxobacteria three quarters of a century ago. Since then, many predatory strains, diverse hunting strategies, environmental consequences and potential applications have been reported by groups all over the world. Now we know that predatory bacteria are distributed in a wide variety of environments and that interactions between predatory and non-predatory populations seem to be the most important factor in bacterial selection and mortality in some ecosystems. Bacterial predation has now been proposed as an evolutionary driving force. The structure and diversity of the predatory bacterial community is beginning to be recognized as an important factor in biodiversity due to its potential role in controlling and modelling bacterial populations in the environment. In this paper, we review the current understanding of bacterial predation, going over the strategies used by the main predatory bacteria to kill their prey. We have also reviewed and integrated the accumulated advances of the last 75 years with the interesting new insights that are provided by the analyses of genomes, predatomes, predatosomes and other comparative genomics studies, focusing on potential applications that derive from all of these areas of study.


Assuntos
Fenômenos Fisiológicos Bacterianos , Animais , Biodiversidade , Evolução Biológica , Cadeia Alimentar , Humanos
14.
BMC Med Genet ; 16: 68, 2015 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-26293599

RESUMO

BACKGROUND: Chromosome 17q21.31 microdeletion syndrome is a multisystem genomic disorder caused by a recurrent 600-kb-long deletion, or haploinsufficiency of the chromatin modifier gene KANSL1, which maps to that region. Patients with KANSL1 intragenic mutations have been reported to display the major clinical features of 17q21.31 microdeletion syndrome. However, they did not exhibit the full clinical spectrum of this disorder, which might indicate that an additional gene or genes, located in the 17q21.31 locus, might also be involved in the syndrome's phenotype. METHODS: Conventional and molecular karyotypes were performed on a female patient with intellectual disability, agenesis of the corpus callosum, heart defects, hydronephrosis, hypotonia, pigmentary skin anomalies and facial dysmorphic features. FISH analysis was conducted for chromosomal breakpoint localization. qRT-PCR was applied for the comparative gene expression of KANSL1 gene in the patient and a control group. RESULTS: Herein, we present the first report of disruption and haploinsufficiency of the KANSL1 gene, secondary to a t(1;17)(q12;q21)dn chromosomal translocation in a girl that also carried a de novo ~289-kb deletion on 16p11.2. KANSL1 gene expression studies and comparative clinical analysis of patients with 17q21.31 deletions and intragenic KANSL1 gene defects indicate that KANSL1 dysfunction is associated with the full spectrum of the 17q21.31 microdeletion syndrome, which includes characteristic facial features, hypotonia, intellectual disability, and structural defects of the brain, heart and genitourinary system, as well as, musculoskeletal and neuroectodermal anomalies. Moreover, we provide further evidence for the overlapping clinical phenotype of this condition with the cardio-facio-cutaneous (CFC) syndrome. CONCLUSIONS: KANSL1 gene haploinsufficiency is necessary and sufficient to cause the full spectrum of the 17q21.31 microdeletion syndrome. We hypothesize that the KANSL1 gene might have an effect on the Ras/mitogen-activated protein kinase (MAPK) pathway activity, which is known to be deregulated in the CFC syndrome. This pathway has a crucial role in the development of the heart and craniofacial morphology, as well as the skin, eye, brain and musculoskeletal systems.


Assuntos
Anormalidades Múltiplas/genética , Deficiência Intelectual/genética , Proteínas Nucleares/genética , Fenótipo , Anormalidades Múltiplas/patologia , Deleção Cromossômica , Cromossomos Humanos Par 17/genética , Primers do DNA/genética , Feminino , Haploinsuficiência/genética , Humanos , Hibridização in Situ Fluorescente , Deficiência Intelectual/patologia , Cariotipagem , Reação em Cadeia da Polimerase Via Transcriptase Reversa
15.
Int J Clin Pharmacol Ther ; 53(7): 541-9, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26073353

RESUMO

Amfepramone, also known as diethylpropion, is an anorectic drug used for the short-term treatment of obesity; however, its efficacy and safety during periods greater than 3 months has been scarcely studied. To evaluate the 6-month efficacy and safety of amfepramone treatment in obese adult Mexican patients resistant to diet and exercise, a double-blinded, randomized, and placebo-controlled clinical trial study was designed on 156 volunteers with a body mass index (BMI) greater than 30 kg/m2 and less than 45 kg/m2. Patients were randomized to receive a 75 mg tablet of amfepramone or placebo daily for 6 months. Primary outcome was the absolute body weight loss, whereas secondary outcomes were the percentage of patients who achieved at least 5% or 10% weight loss, as well as the improvement of anthropometric and metabolic parameters. Amfepramone treatment produced a superior efficacy to decrease body weight than placebo at 3 months (-4.9±0.25 kg vs. -0.7±0.32 kg) and 6 months (-7.7±0.52 kg vs. -1.1±0.7 kg). In addition, 64 and 34 patients achieved at least 5% or 10% weight loss, respectively, with amfepramone at 6 months, compared with 8 and 0 patients on placebo. Amfepramone also significantly improved BMI and waist circumference, but it only showed a favorable tendency in the waist-hip index (WHI), glucose, total cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL), triglycerides, heart rate, systolic blood pressure, and diastolic blood pressure at 3 and 6 months. Amfepramone produced only mild adverse events, and they were presented in a greater number than placebo only at 3 months, dry mouth being the the main adverse event. Data suggest that amfepramone is effective and well tolerated in obese Mexican patients during a 6-month regimen.


Assuntos
Depressores do Apetite/uso terapêutico , Dietilpropiona/uso terapêutico , Obesidade/tratamento farmacológico , Redução de Peso/efeitos dos fármacos , Adulto , Depressores do Apetite/efeitos adversos , Biomarcadores/sangue , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Pressão Sanguínea/efeitos dos fármacos , Índice de Massa Corporal , Dietilpropiona/efeitos adversos , Método Duplo-Cego , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Lipídeos/sangue , Masculino , México/epidemiologia , Obesidade/sangue , Obesidade/diagnóstico , Obesidade/epidemiologia , Obesidade/fisiopatologia , Fatores de Tempo , Resultado do Tratamento , Circunferência da Cintura , Relação Cintura-Quadril
16.
Rev Esp Enferm Dig ; 107(10): 644-6, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26437987

RESUMO

Tumoral conditions in the round ligament of the liver are very uncommon and exhibit nonspecific manifestations, hence a high level of suspicion is necessary for their diagnosis. We report the case of a 47-year-old female patient who presented with abdominal pain for several months; imaging studies showed a lesion of indeterminate nature likely connected with the falciform ligament, and only intraoperative findings acknowledged the presence of an apparently benign tumor in the round ligament of the liver, which biopsy confirmed. Following the excision of the round ligament the patient had a favorable course. As this is a pathologically benign lesion we deem its surgical management both advisable and sufficient. However, because of its small prevalence and the scarcity of literature involving this condition, further studies would be needed to provide information on natural history, treatment, and long-term prognosis.


Assuntos
Leiomioma/cirurgia , Neoplasias Hepáticas/cirurgia , Ligamentos Redondos/cirurgia , Feminino , Humanos , Leiomioma/diagnóstico por imagem , Leiomioma/patologia , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/patologia , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Ligamentos Redondos/diagnóstico por imagem , Ligamentos Redondos/patologia , Tomografia Computadorizada por Raios X
17.
Environ Microbiol ; 16(7): 2341-50, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24707988

RESUMO

Myxococcus xanthus is a social bacterium that preys on prokaryotic and eukaryotic microorganisms. Co-culture of M. xanthus with reference laboratory strains and field isolates of the legume symbiont Sinorhizobium meliloti revealed two different predatory patterns that resemble frontal and wolf-pack attacks. Use of mutants impaired in the two types of M. xanthus surface motility (A or adventurous and S or social motility) and a csgA mutant, which is unable to form macroscopic travelling waves known as ripples, has demonstrated that both motility systems but not rippling are required for efficient predation. To avoid frontal attack and reduce killing rates, rhizobial cells require a functional expR gene. ExpR regulates expression of genes involved in a variety of functions. The use of S. meliloti mutants impaired in several of these functions revealed that the exopolysaccharide galactoglucan (EPS II) is the major determinant of the M. xanthus predatory pattern. The data also suggest that this biopolymer confers an ecological advantage to rhizobial survival in soil, which may have broad environmental implications.


Assuntos
Antibiose/genética , Proteínas de Bactérias/genética , Galactanos/biossíntese , Regulação Bacteriana da Expressão Gênica , Glucanos/biossíntese , Myxococcus xanthus/patogenicidade , Polissacarídeos Bacterianos/biossíntese , Sinorhizobium meliloti/metabolismo , Adaptação Biológica , Proteínas de Bactérias/metabolismo , Viabilidade Microbiana , Movimento , Mutação , Myxococcus xanthus/genética , Myxococcus xanthus/metabolismo , Percepção de Quorum , Sinorhizobium meliloti/genética , Transativadores/genética , Transativadores/metabolismo
18.
PLoS Genet ; 7(6): e1002106, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21655090

RESUMO

The dual toxicity/essentiality of copper forces cells to maintain a tightly regulated homeostasis for this metal in all living organisms, from bacteria to humans. Consequently, many genes have previously been reported to participate in copper detoxification in bacteria. Myxococcus xanthus, a prokaryote, encodes many proteins involved in copper homeostasis that are differentially regulated by this metal. A σ factor of the ECF (extracytoplasmic function) family, CorE, has been found to regulate the expression of the multicopper oxidase cuoB, the P1B-type ATPases copA and copB, and a gene encoding a protein with a heavy-metal-associated domain. Characterization of CorE has revealed that it requires copper to bind DNA in vitro. Genes regulated by CorE exhibit a characteristic expression profile, with a peak at 2 h after copper addition. Expression rapidly decreases thereafter to basal levels, although the metal is still present in the medium, indicating that the activity of CorE is modulated by a process of activation and inactivation. The use of monovalent and divalent metals to mimic Cu(I) and Cu(II), respectively, and of additives that favor the formation of the two redox states of this metal, has revealed that CorE is activated by Cu(II) and inactivated by Cu(I). The activation/inactivation properties of CorE reside in a Cys-rich domain located at the C terminus of the protein. Point mutations at these residues have allowed the identification of several Cys involved in the activation and inactivation of CorE. Based on these data, along with comparative genomic studies, a new group of ECF σ factors is proposed, which not only clearly differs mechanistically from the other σ factors so far characterized, but also from other metal regulators.


Assuntos
Proteínas de Bactérias/metabolismo , Cobre/metabolismo , Myxococcus xanthus/enzimologia , Fator sigma/metabolismo , Proteínas de Bactérias/genética , Sítios de Ligação , DNA/metabolismo , Regulação Bacteriana da Expressão Gênica , Mutação , Fator sigma/genética
19.
Accid Anal Prev ; 198: 107474, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38290408

RESUMO

Distracted driving increases the crash frequencies on the road and subsequently leads to fatalities involved with crashes. As technology has evolved, drivers are continuously exposed to newer technology in their vehicles and applications in their phones, which has led to technology representing one of the main secondary tasks that distract drivers on the road. The impact of technology-involved distraction appears to be different by the type of distraction since a secondary task that can be exceedingly distracting to the driver causes more reckless and risky driving. Moreover, the impact of distracted driving may differ by roadway geometries since distracted drivers' performance may vary depending on how actively they interact with other vehicles or surrounding environments. This study aims to understand the impacts of smartphone application distractions, in particular social media activities (e.g., video, feed, message), on different road geometries using a mixed-method analysis consisting of a survey, a driving simulator experiment, and individual interview. Results from the interview and simulation experiments show that most social media activities cause unsafe lane changes regardless of road geometry. Among various social-media activities, watching reels (videos) represent an unintentional but deeper level of engagement that consequently causes a driver to deviate in their lane, make unintentional lane changes, suddenly change their speed and acceleration, and headway. The interview also revealed varying levels of risk perception about distracted driving, in particular the lower level of risk perception in using GPS and music applications. This study concludes that the distractions caused by smartphone applications and social media activities combined with lower awareness and risk perception could significantly elevate the crash risks.


Assuntos
Condução de Veículo , Direção Distraída , Aplicativos Móveis , Humanos , Acidentes de Trânsito/prevenção & controle , Inquéritos e Questionários , Simulação por Computador , Tecnologia , Direção Distraída/prevenção & controle
20.
Front Microbiol ; 15: 1339696, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38328431

RESUMO

Bacterial predators are widely distributed across a variety of natural environments. Understanding predatory interactions is of great importance since they play a defining role in shaping microbial communities in habitats such as soils. Myxococcus xanthus is a soil-dwelling bacterial predator that can prey on Gram-positive and Gram-negative bacteria and even on eukaryotic microorganisms. This model organism has been studied for many decades for its unusual lifecycle, characterized by the formation of multicellular fruiting bodies filled with myxospores. However, less is known about its predatory behavior despite being an integral part of its lifecycle. Predation in M. xanthus is a multifactorial process that involves several mechanisms working synergistically, including motility systems to efficiently track and hunt prey, and a combination of short-range and contact-dependent mechanisms to achieve prey death and feed on them. In the short-range attack, M. xanthus is best known for the collective production of secondary metabolites and hydrolytic enzymes to kill prey and degrade cellular components. On the other hand, contact-dependent killing is a cell-to-cell process that relies on Tad-like and type III secretion systems. Furthermore, recent research has revealed that metals also play an important role during predation, either by inducing oxidative stress in the prey, or by competing for essential metals. In this paper, we review the current knowledge about M. xanthus predation, focusing on the different mechanisms used to hunt, kill, and feed on its prey, considering the most recent discoveries and the transcriptomic data available.

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