RESUMO
Recently, novel non-pharmacological interventions, such as photobiomodulation (PBM) therapy, have shown promise for the treatment of Alzheimer's disease (AD). This article outlines the translation from the preclinical to clinical stages of an innovative brain-gut PBM therapy in a mouse model of AD, a pilot clinical trial involving mild-to-moderate AD patients, and a continuing pivotal clinical trial with a similar patient population. In a mouse model of AD (Aß25-35), daily application of brain-gut PBM therapy to both the head and the abdomen produced a neuroprotective effect against the neurotoxic effects of an Aß25-35 peptide injection by normalizing all the modified behavioral and biochemical parameters. The pilot clinical trial to evaluate brain-gut PBM therapy demonstrated the tolerability and feasibility of the novel PBM-based treatment for mild-to-moderate AD patients. Compared to the sham patients, the PBM-treated patients had lower Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) comprehension sub-scores, higher forward verbal spans, and lower Trail Making Test (TMT) Part B (TMT-B) execution times, which suggest an improvement in cognitive functions. This pilot study provided important information for the design of a novel pivotal clinical trial, currently in progress, to assess the efficacy of brain-gut PBM therapy in a larger sample of AD patients. This pivotal clinical trial could demonstrate that brain-gut PBM therapy is a safe, well-tolerated, and efficient disease-modifying treatment for mild-to-moderate AD patients and that it has medical and economic benefits.
Assuntos
Doença de Alzheimer , Terapia com Luz de Baixa Intensidade , Animais , Camundongos , Humanos , Doença de Alzheimer/radioterapia , Doença de Alzheimer/tratamento farmacológico , Projetos Piloto , Encéfalo , CogniçãoRESUMO
PURPOSE: Osteoradionecrosis (ORN) of the mandible is a serious complication of head and neck radiotherapy. This study aims to investigate the effect of hyperbaric oxygen (HBO) treatment on ORN in two randomized, controlled multicentre trials. METHODS AND MATERIALS: Patients with ORN with indication for surgical treatment were randomised to either group 1: surgical removal of necrotic mandibular bone supplemented by 30 pre- and 10 postoperative HBO exposures at 243 kPa for 90 min each, or group 2: surgical removal of necrotic bone only. Primary outcome was healing of ORN one year after surgery evaluated by a clinically adjusted version of the Common Toxicity Criteria of Adverse Events (CTCAE) v 3.0. Secondary outcomes included xerostomia, unstimulated and stimulated whole salivation rates, trismus, dysphagia, pain, Activities of Daily Living (ADL) and quality of life according to EORTC. Data were combined from two separate trials. Ninety-seven were enrolled and 65 were eligible for the intent-to-treat analysis. The 33% drop-out was equally distributed between groups. RESULTS: In group 1, 70% (21/30) healed compared to 51% (18/35) in group 2. HBO was associated with an increased chance of healing independent of baseline ORN grade or smoking status as well as improved xerostomia, unstimulated whole salivary flow rate, and dysphagia. Due to insufficient recruitment, none of the endpoints reached a statistically significant difference between groups. ADL data could only be obtained from 50 patients. CONCLUSION: Hyperbaric oxygen did not significantly improve the healing outcome of osteoradionecrosis after surgical removal of necrotic bone as compared to standard care (70% vs. 51%). This effect is not statistically significant due to the fact that the study was underpowered and is therefore prone to type II error.
Assuntos
Transtornos de Deglutição , Neoplasias de Cabeça e Pescoço , Oxigenoterapia Hiperbárica , Osteorradionecrose , Xerostomia , Atividades Cotidianas , Transtornos de Deglutição/terapia , Neoplasias de Cabeça e Pescoço/terapia , Humanos , Oxigenoterapia Hiperbárica/efeitos adversos , Mandíbula , Osteorradionecrose/etiologia , Osteorradionecrose/terapia , Oxigênio , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Xerostomia/terapiaRESUMO
BACKGROUND: Infertility is defined as the inability to conceive after 12 months of unprotected intercourse. It affects approximately one in six couples seeking pregnancy in France or western countries. Many lifestyle factors of the couples' pre and peri-conceptional environment (weight, diet, alcohol, tobacco, coffee, drugs, physical activity, stress, sleep ) have been identified as risk factors for infertility in both males and females. The high prevalence rates of unhealthy diets and lifestyles in the reproductive population of industrialized countries are worrisome. Nevertheless, adoption of a healthy lifestyle may improve fertility but lifestyle changes are difficult to achieve and to maintain due notably to behavioral factors. METHODS: Consequently, we decided to propose an interventional study aimed at improving the quality of life of infertile couples before the start of assisted reproductive technology treatment. It is a randomized controlled multicentre trial. Both members of the couples are involved in an integrated global care program (PEPCI for "Parcours Environnement PériConceptionnel en Infertilité") vs. usual care. This global intervention not only considers diet and/or physical activity but follows a holistic approach, including a multidisciplinary assessment to address complete physical, psychological and social well-being. According to patient needs, this includes interventions on weight, exercise, diet, alcohol and drugs, mental and social health. DISCUSSION: The main objective of trial is to demonstrate that periconceptional multidisciplinary care has a positive impact on reproductive functions. We will also focus on feasibility, acceptance, compliance and conditions of success of a multifaceted lifestyle intervention. TRIAL REGISTRATION: The trial was registered at ClinicalTrials.gov, Identifier: NCT02961907 on November 11, 2016.
Assuntos
Estilo de Vida Saudável , Infertilidade/terapia , Adolescente , Adulto , Peso Corporal , Dieta , Exercício Físico , Feminino , França , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Multicêntricos como Assunto , Gravidez , Taxa de Gravidez , Ensaios Clínicos Controlados Aleatórios como Assunto , Projetos de Pesquisa , Adulto JovemRESUMO
BACKGROUND: Changes in the gut microbiota have been implicated in mood and cognition. In rodents, supplementation with certain bacteria have been shown to alleviate adverse effects of stress on gut microbiota composition and behaviour, but little is known of how the performance of different strains compare to each other. We took a systematic approach to test the efficacy of twelve candidate probiotic strains from ten species/sub-species of Bifidobacterium and Lactobacillus on behaviours and neuroendocrine responses of chronically stressed mice. METHODS: The strains were tested in four screening experiments with non-stressed and chronically stressed vehicle groups. The three most efficacious strains were re-tested to validate the results. Mice were administered a daily oral gavage containing either 1 × 109 colony forming units (CFU) of selected candidate probiotic or saline solution for one week prior to and for three weeks during daily chronic restraint stress. Behavioural tests including the elevated plus maze, open field, novel object recognition, and forced swim test were applied during week five. Corticosterone and adrenocorticotropic hormone (ACTH) were analysed to measure the neuroendocrine response to stress. Plasma and tissue samples were collected for biomarker analyses. RESULTS: Of the twelve candidate probiotics, Lactobacillus paracasei Lpc-37, Lactobacillus plantarum LP12407, Lactobacillus plantarum LP12418 and Lactobacillus plantarum LP12151 prevented stress-associated anxiety and depression-related behaviours from developing compared with chronically stressed vehicle mice. In addition, Lpc-37 improved cognition. CONCLUSION: This systematic screening indicates species- and strain-dependent effects on behavioural outcomes related to stress and further suggests that strains differ from each other in their effects on potential mechanistic outcomes.
Assuntos
Ansiedade , Comportamento Animal , Bifidobacterium , Disfunção Cognitiva , Depressão , Microbioma Gastrointestinal , Lactobacillus , Probióticos/farmacologia , Restrição Física , Estresse Psicológico , Animais , Ansiedade/dietoterapia , Ansiedade/etiologia , Ansiedade/metabolismo , Comportamento Animal/fisiologia , Disfunção Cognitiva/dietoterapia , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/metabolismo , Depressão/dietoterapia , Depressão/etiologia , Depressão/metabolismo , Suplementos Nutricionais , Microbioma Gastrointestinal/fisiologia , Masculino , Camundongos , Estresse Psicológico/complicações , Estresse Psicológico/dietoterapia , Estresse Psicológico/metabolismoRESUMO
Isolated microspore culture (IMC) is the most efficient way to produce large numbers of doubled-haploid (DH) barley plants in a short time. Yet, while IMC is more cost-efficient and less labor-intensive than anther culture, it is technically more complex and requires more experienced personnel if it is to yield its full potential. In part, this is because of multiple and important interactions that exist between factors at its many different phases, including genotype effects as well. When every phase is fine-tuned, the protocol that is presented below yields a useful number of DHs with almost all genotypes and can allow the production of up to 300 DH plants from a single F1 plant in just a few months.
Assuntos
Hordeum/crescimento & desenvolvimento , Pólen/crescimento & desenvolvimento , Técnicas de Cultura de Tecidos/métodos , Aclimatação , Cromossomos de Plantas/genética , Meios de Cultura , Desinfecção , Genótipo , Germinação , Hordeum/genética , Técnicas de Embriogênese Somática de Plantas , Regeneração , Sementes/embriologiaRESUMO
Saccharomyces cerevisiae and Candida albicans are model yeasts for biotechnology and human health, respectively. We used atomic force microscopy (AFM) to explore the effects of caspofungin, an antifungal drug used in hospitals, on these two species. Our nanoscale investigation revealed similar, but also different, behaviors of the two yeasts in response to treatment with the drug. While administration of caspofungin induced deep cell wall remodeling in both yeast species, as evidenced by a dramatic increase in chitin and decrease in ß-glucan content, changes in cell wall composition were more pronounced with C. albicans cells. Notably, the increase of chitin was proportional to the increase in the caspofungin dose. In addition, the Young modulus of the cell was three times lower for C. albicans cells than for S. cerevisiae cells and increased proportionally with the increase of chitin, suggesting differences in the molecular organization of the cell wall between the two yeast species. Also, at a low dose of caspofungin (i.e., 0.5× MIC), the cell surface of C. albicans exhibited a morphology that was reminiscent of cells expressing adhesion proteins. Interestingly, this morphology was lost at high doses of the drug (i.e., 4× MIC). However, the treatment of S. cerevisiae cells with high doses of caspofungin resulted in impairment of cytokinesis. Altogether, the use of AFM for investigating the effects of antifungal drugs is relevant in nanomedicine, as it should help in understanding their mechanisms of action on fungal cells, as well as unraveling unexpected effects on cell division and fungal adhesion.
Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Equinocandinas/farmacologia , Saccharomyces cerevisiae/efeitos dos fármacos , Candida albicans/citologia , Caspofungina , Adesão Celular/efeitos dos fármacos , Divisão Celular , Parede Celular/efeitos dos fármacos , Quitina/metabolismo , Avaliação Pré-Clínica de Medicamentos , Módulo de Elasticidade , Lipopeptídeos , Testes de Sensibilidade Microbiana , Microscopia de Força Atômica , Nanotecnologia/métodos , Saccharomyces cerevisiae/citologia , beta-Glucanas/metabolismoRESUMO
Parkinsonian tremor is among the most emblematic medical signs and is one of the cardinal manifestations of Parkinson's disease (PD). Its semiology has been extensively addressed by ancient and contemporary medical literature, but more attention has been dedicated to its medical treatment in the past than nowadays. Among the hundreds of studies performed to determine the value of medical and surgical approaches on motor and non motor signs of PD, only a minority specifically considered effect on tremor as an efficacy outcome. Current available guidelines for PD treatment include attempts to specifically address tremor treatment but stress the low level of evidences available. In these conditions, with its still poorly understood pathophysiological basis and variable clinical expression PD tremor treatment is a clinical challenge. Only surgery (lesion or high frequency stimulation) of discrete deep brain targets consistently provides symptomatic long lasting alleviation. Through revision of contemporary scientific evidence, the purpose of this paper is to offer a systematic pragmatic approach to symptomatic management of tremor as one of the distinctive signs of PD that may generate substantial disability.
Assuntos
Doença de Parkinson/epidemiologia , Doença de Parkinson/terapia , Tremor/epidemiologia , Tremor/terapia , Animais , Antiparkinsonianos/uso terapêutico , Terapia por Estimulação Elétrica/métodos , Terapia por Estimulação Elétrica/tendências , Humanos , Doença de Parkinson/diagnóstico , Radiocirurgia/métodos , Radiocirurgia/tendências , Resultado do Tratamento , Tremor/diagnósticoRESUMO
BACKGROUND: The fungal pathogen Fusarium graminearum causes Fusarium Head Blight (FHB) disease on wheat which can lead to trichothecene mycotoxin (e.g. deoxynivalenol, DON) contamination of grain, harmful to mammalian health. DON is produced at low levels under standard culture conditions when compared to plant infection but specific polyamines (e.g. putrescine and agmatine) and amino acids (e.g. arginine and ornithine) are potent inducers of DON by F. graminearum in axenic culture. Currently, host factors that promote mycotoxin synthesis during FHB are unknown, but plant derived polyamines could contribute to DON induction in infected heads. However, the temporal and spatial accumulation of polyamines and amino acids in relation to that of DON has not been studied. RESULTS: Following inoculation of susceptible wheat heads by F. graminearum, DON accumulation was detected at two days after inoculation. The accumulation of putrescine was detected as early as one day following inoculation while arginine and cadaverine were also produced at three and four days post-inoculation. Transcripts of ornithine decarboxylase (ODC) and arginine decarboxylase (ADC), two key biosynthetic enzymes for putrescine biosynthesis, were also strongly induced in heads at two days after inoculation. These results indicated that elicitation of the polyamine biosynthetic pathway is an early response to FHB. Transcripts for genes encoding enzymes acting upstream in the polyamine biosynthetic pathway as well as those of ODC and ADC, and putrescine levels were also induced in the rachis, a flower organ supporting DON production and an important route for pathogen colonisation during FHB. A survey of 24 wheat genotypes with varying responses to FHB showed putrescine induction is a general response to inoculation and no correlation was observed between the accumulation of putrescine and infection or DON accumulation. CONCLUSIONS: The activation of the polyamine biosynthetic pathway and putrescine in infected heads prior to detectable DON accumulation is consistent with a model where the pathogen exploits the generic host stress response of polyamine synthesis as a cue for production of trichothecene mycotoxins during FHB disease. However, it is likely that this mechanism is complicated by other factors contributing to resistance and susceptibility in diverse wheat genetic backgrounds.
Assuntos
Fusarium/metabolismo , Poliaminas/metabolismo , Putrescina/metabolismo , Tricotecenos/metabolismo , Triticum/metabolismo , Aminoácidos/metabolismo , Vias Biossintéticas , Carboxiliases/genética , Carboxiliases/metabolismo , DNA Complementar/química , DNA Complementar/genética , Fusarium/fisiologia , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno , Dados de Sequência Molecular , Micotoxinas/metabolismo , Ornitina Descarboxilase/genética , Ornitina Descarboxilase/metabolismo , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Análise de Sequência de DNA , Espermidina/metabolismo , Espermina/metabolismo , Triticum/genética , Triticum/microbiologiaRESUMO
A new ambulatory method of monitoring physical activities in Parkinson's disease (PD) patients is proposed based on a portable data-logger with three body-fixed inertial sensors. A group of ten PD patients treated with subthalamic nucleus deep brain stimulation (STN-DBS) and ten normal control subjects followed a protocol of typical daily activities and the whole period of the measurement was recorded by video. Walking periods were recognized using two sensors on shanks and lying periods were detected using a sensor on trunk. By calculating kinematics features of the trunk movements during the transitions between sitting and standing postures and using a statistical classifier, sit-to-stand (SiSt) and stand-to-sit (StSi) transitions were detected and separated from other body movements. Finally, a fuzzy classifier used this information to detect periods of sitting and standing. The proposed method showed a high sensitivity and specificity for the detection of basic body postures allocations: sitting, standing, lying, and walking periods, both in PD patients and healthy subjects. We found significant differences in parameters related to SiSt and StSi transitions between PD patients and controls and also between PD patients with and without STN-DBS turned on. We concluded that our method provides a simple, accurate, and effective means to objectively quantify physical activities in both normal and PD patients and may prove useful to assess the level of motor functions in the latter.
Assuntos
Aceleração , Atividades Cotidianas , Diagnóstico por Computador/métodos , Monitorização Ambulatorial/instrumentação , Atividade Motora , Doença de Parkinson/diagnóstico , Doença de Parkinson/fisiopatologia , Inteligência Artificial , Terapia por Estimulação Elétrica , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Ambulatorial/métodos , Doença de Parkinson/reabilitação , Resultado do TratamentoRESUMO
Pectins of varying structures were tested for their ability to interact with cellulose in comparison to the well-known adsorption of xyloglucan. Our results reveal that sugar beet (Beta vulgaris) and potato (Solanum tuberosum) pectins, which are rich in neutral sugar side chains, can bind in vitro to cellulose. The extent of binding varies with respect to the nature and structure of the side chains. Additionally, branched arabinans (Br-Arabinans) or debranched arabinans (Deb-Arabinans; isolated from sugar beet) and galactans (isolated from potato) were shown bind to cellulose microfibrils. The adsorption of Br-Arabinan and galactan was lower than that of Deb-Arabinan. The maximum adsorption affinity of Deb-Arabinan to cellulose was comparable to that of xyloglucan. The study of sugar beet and potato alkali-treated cell walls supports the hypothesis of pectin-cellulose interaction. Natural composites enriched in arabinans or galactans and cellulose were recovered. The binding of pectins to cellulose microfibrils may be of considerable significance in the modeling of primary cell walls of plants as well as in the process of cell wall assembly.
Assuntos
Celulose/metabolismo , Pectinas/química , Pectinas/metabolismo , Beta vulgaris , Biopolímeros/química , Biopolímeros/metabolismo , Celulose/química , Glucanos/química , Glucanos/metabolismo , Cinética , Solanum tuberosum , Xilanos/química , Xilanos/metabolismoRESUMO
An ambulatory gait analysis method using body-attached gyroscopes to estimate spatio-temporal parameters of gait has been proposed and validated against a reference system for normal and pathologic gait. Later, ten Parkinson's disease (PD) patients with subthalamic nucleus deep brain stimulation (STN-DBS) implantation participated in gait measurements using our device. They walked one to three times on a 20-m walkway. Patients did the test twice: once STN-DBS was ON and once 180 min after turning it OFF. A group of ten age-matched normal subjects were also measured as controls. For each gait cycle, spatio-temporal parameters such as stride length (SL), stride velocity (SV), stance (ST), double support (DS), and gait cycle time (GC) were calculated. We found that PD patients had significantly different gait parameters comparing to controls. They had 52% less SV, 60% less SL, and 40% longer GC. Also they had significantly longer ST and DS (11% and 59% more, respectively) than controls. STN-DBS significantly improved gait parameters. During the stim ON period, PD patients had 31% faster SV, 26% longer SL, 6% shorter ST, and 26% shorter DS. GC, however, was not significantly different. Some of the gait parameters had high correlation with Unified Parkinson's Disease Rating Scale (UPDRS) subscores including SL with a significant correlation (r = -0.90) with UPDRS gait subscore. We concluded that our method provides a simple yet effective way of ambulatory gait analysis in PD patients with results confirming those obtained from much more complex and expensive methods used in gait labs.
Assuntos
Diagnóstico por Computador/métodos , Transtornos Neurológicos da Marcha/diagnóstico , Marcha , Monitorização Ambulatorial/instrumentação , Monitorização Ambulatorial/métodos , Doença de Parkinson/diagnóstico , Transdutores , Aceleração , Idoso , Algoritmos , Diagnóstico por Computador/instrumentação , Terapia por Estimulação Elétrica/métodos , Desenho de Equipamento , Feminino , Transtornos Neurológicos da Marcha/etiologia , Transtornos Neurológicos da Marcha/reabilitação , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/complicações , Doença de Parkinson/reabilitação , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Side chains of sugar beet (Beta vulgaris) pectins, which are mainly composed of arabinose (Ara) and galactose (Gal) residues, are esterified by ferulic acid units. Enzymatic hydrolysis of beet cell walls yielded several feruloylated oligosaccharides, which were separated by hydrophobic interaction chromatography. Two new oligomers were isolated in the fraction eluted by 25:75 (v/v) ethanol:water. An arabinotriose and an arabinotetraose esterified by two ferulic acid residues were obtained, and their structure was elucidated by mass spectrometry. It is shown that feruloyl groups are linked to O-5 of Ara residues, in addition to the known O-2 position. This work establishes for the first time, to our knowledge, that two neighboring Ara units may be esterified by two ferulic acid units. This close proximity may have important biochemical implications.
Assuntos
Beta vulgaris/metabolismo , Ácidos Cumáricos/metabolismo , Oligossacarídeos/metabolismo , Polissacarídeos/metabolismo , Parede Celular/metabolismo , Esterificação , Estrutura Molecular , Oligossacarídeos/química , Oligossacarídeos/isolamento & purificação , Polissacarídeos/química , Polissacarídeos/isolamento & purificação , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
BACKGROUND: Subthalamic nucleus (STN) deep brain stimulation (DBS) of patients with PD allows reduction of antiparkinsonian medication but has only a mild direct effect on dyskinesia. Since antiparkinsonian medication has short- and long-term effects that may prevent an estimate of the maximal possible impact of STN DBS, such medication was used at the lowest possible dosage after DBS implantation. OBJECTIVE: To study the maximal and long-term effects of STN DBS using the lowest dose of medication. METHODS: Twenty consecutive patients with PD with motor fluctuations and dyskinesia underwent bilateral implantation under stereotactic guidance, microrecording, and clinical control. All medications were stopped before implantation and reintroduced, at the lowest dosage needed, only if the postoperative motor score did not reach the baseline level. Unified PD Rating Scale (UPDRS) motor (subscale III) scores were measured at baseline and after 3, 6, 12, and 24 months. RESULTS: After 21 plus minus 8 months, the UPDRS III "off-medication" score was decreased by 45% and was similar to the preoperative UPDRS III "on" score. Overall, medication was reduced by 79%, being completely withdrawn in 10 patients. Fluctuations and dyskinesia showed an overall reduction of >90%, disappearing completely in patients without medication. These improvements were maintained for 2 years. CONCLUSIONS: These results show that STN DBS could replace levodopa and allowed all antiparkinsonian medication to be discontinued in 50% of patients with PD. Fluctuations and dyskinesia disappeared completely in these patients but persisted in those still on medication. These improvements were maintained for 2 years.
Assuntos
Antiparkinsonianos/uso terapêutico , Terapia por Estimulação Elétrica , Levodopa/uso terapêutico , Doença de Parkinson/tratamento farmacológico , Núcleo Subtalâmico/fisiologia , Idoso , Terapia Combinada , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do TratamentoRESUMO
Strains of Saccharomyces cerevisiae deleted for TPS1 encoding trehalose-6-phosphate synthase still accumulate trehalose when harbouring a functional MAL locus. We demonstrate that this accumulation results from an active uptake of trehalose present in the 'yeast extract' used to make the enriched culture media and that no accumulation is observed in mineral media. The uptake of trehalose was shown to be mediated by the alpha-glucoside transporter encoded by AGT1, the expression of which is linked to the presence of a functional MAL locus. Deletion of this gene in a MAL+ tps1 mutant abolished trehalose accumulation on a maltose or galactose mineral medium. However, small amounts of disaccharide were still detected in a agt1 tps1 double mutant when the medium was supplemented with 10 g trehalose l(-1), indicating the existence of a non-concentrative low-affinity sugar transporter. The presence of the high-affinity trehalose permease allowed us to investigate the effect of increasing exogenous trehalose from 0 to 10 g(-1) on intracellular accumulation. A maximum of ca. 10% (wt/wt dry cells) trehalose was attained in the presence of only 1 g l(-1) of disaccharide in the medium. The capability to monitor the intracellular content of trehalose by varying its extracellular concentration, independent of genetic alterations of the trehalose metabolic machinery, allowed the remarkable contribution of this molecule in stress tolerance to be demonstrated, as the higher the trehalose content, the longer the cell survival to a severe heat shock and to glucose starvation.
Assuntos
Proteínas de Transporte de Monossacarídeos , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Simportadores , Trealose/metabolismo , Transporte Biológico , Proteínas de Transporte/fisiologia , Meios de Cultura , Fermentação , Proteínas Fúngicas/fisiologia , Temperatura Alta , Maltose/metabolismoRESUMO
The possibility of designing antisense oligodeoxynucleotides complementary to non-adjacent single-stranded sequences containing hairpin structures was studied using a DNA model system. The structure and stability of complexes formed by a 17mer oligonucleotide with DNA fragments containing hairpin structures was investigated by spectroscopic measurements (melting curves) and chemical reactions (osmium tetroxide reaction, copper-phenanthroline cleavage). A three-way junction was formed when the oligonucleotide was bound to both sides of the hairpin structure. When the complementary sequences of the two parts of the oligonucleotide were separated by a sequence which could not form a hairpin, the oligonucleotide exhibited a slightly weaker binding than to the hairpin-containing target. An oligodeoxynucleotide-phenanthroline conjugate was designed to form Watson-Crick base pairs with two single-stranded regions flanking a hairpin structure in a DNA fragment. In the presence of Cu2+ ions and a reducing agent, two main cleavage sites were observed at the end of the duplex structure formed by the oligonucleotide-phenanthroline conjugate with its target sequence. Competition experiments showed that both parts of the oligonucleotide must be bound in order to observe sequence-specific cleavage. Cleavage was still observed with target sequences which could not form a hairpin, provided the reaction was carried out at lower temperatures. These results show that sequence-specific recognition and modification (cleavage) can be achieved with antisense oligonucleotides which bind to non-adjacent sequences in a single-stranded nucleic acid.
Assuntos
DNA/química , DNA/metabolismo , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos/química , Oligodesoxirribonucleotídeos/metabolismo , Composição de Bases , Sequência de Bases , Substâncias Intercalantes , Dados de Sequência Molecular , Oligonucleotídeos Antissenso , Tetróxido de Ósmio , Fenantrolinas/metabolismo , EspectrofotometriaRESUMO
The nuclease activity of 1,10-phenanthroline copper ion was targeted to a specific sequence by attachment of the ligand to the 5' or 3' end of octathymidylates. An acridine derivative was also attached to the other end of the oligothymidylate-phenanthroline conjugate. The duplex formed by the oligothymidylate with its complementary sequence was stabilized by intercalation of the acridine derivative. The reaction induced by 3-mercaptopropionic acid led to a very localized cleavage of a 27-nucleotide-long DNA fragment containing a (dA)8 sequence. At high NaCl concentration or in the presence of spermine, cleavage of the single-stranded 27-mer fragment occurred on both sides of the target sequence. This was ascribed to the formation of a triple helix involving two 1,10-phenanthroline-octathymidylate strands that adopt an antiparallel orientation with respect to each other. When a 27-mer duplex was used as a substrate, cleavage sites were observed on both strands. The location of the cleavage sites led us to conclude that the octathymidylate was bound to the (dA)8.(dT)8 sequence in a parallel orientation with respect to the (dA)8-containing strand. This result reflects the ability of thymine to form two hydrogen bonds with an adenine already engaged in a Watson-Crick base pair. This study shows that it is possible to design DNA-binding oligodeoxynucleotides that could selectively recognize and cleave polypurine-polypyrimidine sequences in double-stranded DNA.
Assuntos
DNA de Cadeia Simples , DNA , Oligodesoxirribonucleotídeos , Fenantrolinas , Sequência de Bases , Indicadores e Reagentes , Cinética , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos/síntese química , Concentração OsmolarRESUMO
Oligodeoxynucleotides can be synthesized by using the alpha anomers of nucleoside units. Oligo-alpha-deoxynucleotides are resistant to nucleases and could be used to regulate gene expression in vivo. Theoretical calculations were carried out to determine the conformational energy of an oligomeric alpha-beta duplex (dA)5.(dT)5 where the adenosine strand contains natural beta-deoxyribonucleotides and the thymidine strand contains synthetic alpha-deoxyribonucleotides. These calculations predict that in the more stable B-like conformation the two strands of the double helix should run parallel to each other whereas in the more stable A-like conformation the two strands should adopt an antiparallel orientation. In order to test these predictions 1,10-phenanthroline was covalently attached to the 5'-end of an alpha-octathymidylate. In the presence of copper ions and a reducing agent (beta-mercaptopropionic acid), the (phenanthroline)2-copper complex generates OH. radicals that cleave phosphodiester bonds in the complementary sequence to which the alpha-octathymidylate is bound. By use of a 27mer oligo-beta-deoxynucleotide containing an octadeoxyadenylate sequence as a target for the phenanthroline-substituted alpha-(dT)8, cleavage was observed on the 5'-side of the (dA)8 sequence, demonstrating that the alpha-beta DNA-DNA hybrid formed a double helix with parallel orientation of the two strands. The same result was obtained when alpha-(dT)8 was bound to beta-(dA)n with n = 8 or 10. When a beta-oligoriboadenylate was used as a target, cleavage occurred exclusively on the 3'-side of the (rA)8 or (rA)10 sequence, indicating that the alpha-beta DNA-RNA hybrid formed a double helix with an antiparallel orientation of the two strands. When a phenanthroline-substituted beta-octathymidylate was used instead of the alpha-octathymidylate, an antiparallel double helix was formed independently of whether the target beta sequence was a DNA or an RNA.
Assuntos
DNA , Conformação de Ácido Nucleico , Fenantrolinas , RNA , Nucleotídeos de Timina , Sequência de Bases , DNA de Cadeia Simples , TermodinâmicaRESUMO
In modern cataract surgery the introduction of akinesia, the corneal incision, the intracapsular extraction with forceps or cryo-stick, the zonulolysis and measures against complications and the optic correction of unilateral cataract with contact lenses can be seen as definite advances. Critically seen, the use of the operating microscope for senile cataract is not necessary, as the binocular loupe is fully sufficient. In the same way the selective use of zonulolysis - but not after the age of 55 - and of the cryo-stick - only on a stretched lans capsule is advised. Also the artificial pupillary lens is not recommended because of the excellent functional results of the contact lens. The same argument applies to emulsification of the crystalline lens. Also, from our experience, the routine use of antibiotics is not necessary. As well as the actual operation methods, including premedication, the methods used to avoid complications are finally and thoroughly discussed.