Site-directed mutagenesis of the ATM promoter: Consequences for response to proliferation and ionizing radiation

Although ATM, the protein defective in ataxia-telangiectasia (A-T), is activated primarily by radiation, there is also evidence that expression of the protein can be regulated by both radiation and growth factors. Computer analysis of the ATM promoter proximal 700-bp sequence reveals a number of potentially important cis-regulatory sequences. Using nucleotide substitutions to delete putative functional elements in the promoter of ATM, we examined the importance of some of these sites for both the basal and the radiation-induced activity of the promoter. In lymphoblastoid cells, most of the mutations in transcription factor consensus sequences [Sp1(1), Sp1(2), Cre, Ets, Xre, gammaIre(2), a modified AP1 site (Fse), and GCF] reduced basal activity to various extents, whereas others [gammaIre(1), NF1, Myb] left basal activity unaffected. In human skin fibroblasts, results were generally the same, but the basal activity varied up to 8-fold in these and other cell lines. Radiation activated the promoter approximately 2.5-fold in serum-starved lymphoblastoid cells, reaching a maximum by 3 hr, and all mutated elements equally blocked this activation. Reduction in Sp1 and AP1 DNA binding activity by serum starvation was rapidly reversed by exposure of cells to radiation. This reduction was not evident in A-T cells, and the response to radiation was less marked. Data provided for interaction between ATM and Sp1 by protein binding and co-immunoprecipitation could explain the altered regulation of Sp1 in A-T cells. The data described here provide additional evidence that basal and radiation-induced regulation of the ATM promoter is under multifactorial control. (C) 2003 Wiley-Liss, Inc.

The use of 16s rDNA restriction fragment length polymorphism analysis for the identification of non-fermenting gram negative bacilli in a cystic fibrosis microbiology referral service

The utility of 16s rDNA restriction fragment length polymorphism (RFLP) analysis for the partial genomovar differentiation of Burkholderia cepacia complex bacterium is well documented. We compared the 16s rDNA RFLP signatures for a number of non-fermenting gram negative bacilli (NF GNB) LMG control strains and clinical isolates pertaining to the genera Burkholderia, Pseudomonas, Achromobacter (Alcaligenes), Ralstonia, Stenotrophomonas and Pandoraea. A collection of 24 control strain (LMG) and 25 clinical isolates were included in the study. Using conventional PCR, a 1.2 kbp 16s rDNA fragment was generated for each organism. Following restriction digestion and electrophoresis, each clinical isolate RFLP signature was compared to those of the control strain panel. Nineteen different RFLP signatures were detected from the 28 control strains included in the study. TwentyoneyTwenty- five of the clinical isolates could be classified by RFLP analysis into a single genus and species when compared to the patterns produced by the control strain panel. Four clinical B. pseudomallei isolates produced RFLP signatures which were indistinguishable from B. cepacia genomovars I, III and VIII. The identity of these four isolates were confirmed using B. pseudomallei specific PCR. 16s rDNA RFLP analysis can be a useful identification strategy when applied to NF GNB, particularly for those which exhibit colistin sulfate resistance. The use of this molecular based methodology has proved very useful in the setting of a CF referral laboratory particularly when utilised in conjunction with B. cepacia complex and genomovar specific PCR techniques. Species specific PCR or sequence analysis should be considered for selected isolates; especially where discrepancies between epidemiology, phenotypic and genotypic characteristics occur.

Combining nonthermal technologies to control foodborne microorganisms

Novel nonthermal processes, such as high hydrostatic pressure (HHP), pulsed electric fields (PEFs), ionizing radiation and ultrasonication, are able to inactivate microorganisms at ambient or sublethal temperatures. Many of these processes require very high treatment intensities, however, to achieve adequate microbial destruction in low-acid foods. Combining nonthermal processes with conventional preservation methods enhances their antimicrobial effect so that lower process intensities can be used. Combining two or more nonthermal processes can also enhance microbial inactivation and allow the use of lower individual treatment intensities. For conventional preservation treatments, optimal microbial control is achieved through the hurdle concept, with synergistic effects resulting from different components of the microbial cell being targeted simultaneously. The mechanisms of inactivation by nonthermal processes are still unclear; thus, the bases of synergistic combinations remain speculative. This paper reviews literature on the antimicrobial efficiencies of nonthermal processes combined with conventional and novel nonthermal technologies. Where possible, the proposed mechanisms of synergy is mentioned. (C) 2003 Elsevier Science B.V. All rights reserved.

Comparative study of the radiation-induced grafting of styrene onto poly(tetrafluoroethylene-co-perfluoropropylvinyl ether) and polypropylene substrates. I: Kinetics and structural investigation

A comparative study has been made of the radiation grafting of styrene onto poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA) and polypropylene (PP) substrates, using the simultaneous irradiation method. Effects of grafting conditions such as monomer concentrations, type of solvent, dose rate and irradiation dose on the grafting yield were investigated. Under the same grafting conditions it was found that a higher degree of grafting of styrene was obtained using a mixture of dichloromethane/methanol solvents for PFA and methanol for PP and the degree of grafting was higher in PP than in PFA at all doses. However, the micro-Raman spectroscopy analysis of the graft revealed that, for the same degree of grafting, the penetration depth of the grafted polystyrene into the substrate was higher in PFA than in PP substrates. In both polymers the crystallinity was hardly affected by the grafting process and the degree of crystallinity decreased slightly with grafting dose. The dependence of the initial rate of grafting on the dose rate and the monomer concentration was found to be 0.6 and 1.4 order for PFA and 0.15 and 2.2 for PP, respectively. The degree of grafting increased with increasing radiation dose in both polymers. However, the grafting yield decreased with an increase in the dose rate. The increase in the overall grafting yield for PFA and PP was accompanied by a proportional increase in the penetration depth of the graft into the substrates. (C) 2003 Society of Chemical Industry.

A study of the radiation degradation of styrene/alkane and α-methylstyrene/alkane copolymers

The effects of copolymer composition and microstructure on the radiation chemistry of styrene/alkane and alpha-methylstyrene/alkane copolymers have been studied. The primary radical species formed on radiolysis of the copolymers at 77 K, and identified by ESR spectroscopy, are the same as those formed during radiolysis of the homopolymers. The yields of radicals for the copolymer are as predicted assuming that the cross-section is proportional to the electron density of each component; however, there is some evidence of radical migration to aromatic groups at 77 K. Changes in molecular structure on irradiation were detected by using C-13 NMR spectroscopy. Evidence of the consumption of terminal double bonds, and chain scission in alpha-methylstyrene/alkane copolymers was found. Measurements of viscosity supported the mechanism of cross-linking predominating in styrene/alkane copolymers, while in alpha-methylstyrene/alkane copolymers chain scission was the major result of irradiation. (C) 2003 Society of Chemical Industry.

A study of the radiation chemistry of poly(chlorotrifluoroethylene) by ESR spectroscopy

The ESR spectra of poly(chlorotrifluoroethylene) were recorded following gamma-radiolysis under vacuum at room temperature and 77 K. The very broad spectrum at 77 K revealed little fine structure with which to identity the radicals formed upon irradiation, but subsequent photobleaching and annealing studies, together with radiolytic studies at higher temperatures, afforded scope for making radical assignments. Both main-chain radicals and a range of chain-end radicals have been identified. The G-values for radical formation were 1.55, 0.36 and 0.32 at 77 K, 273 K and room temperature, respectively. (C) 2003 Elsevier Science Ltd. All rights reserved.

High energy radiation grafting of fluoropolymers

Fluoropolymers are known as chemically inert materials with good high temperature resistance, so they are often the materials of choice for harsh chemical environments. These properties arise because the carbon-fluorine bond is the strongest of all bonds between other elements and carbon, and, because of their large size, fluorine atoms can protect the carbon backbone of polymers such as poly(tetrafluoroethylene), PTFE, from chemical attack. However, while the carbon-fluorine bond is much stronger than the carbon hydrogen bond, the G values for radical formation on high energy radiolysis of fluoropolymers are roughly comparable to those of their protonated counterparts. Thus, efficient high energy radiation grafting of fluoropolymers is practical, and this process can be used to modify either the surface or bulk properties of a fluoropolymer. Indeed, radiation grafted fluoropolymers are currently being used as separation membranes for fuel cells, hydrophilic filtration membranes and matrix substrate materials for use in combinatorial chemistry. Herein we present a review of recent studies of the high energy radiation grafting of fluoropolymers and of the analytical methods available to characterize the grafts. (C) 2003 Elsevier Ltd. All rights reserved.

The genetics of glycosylation in Gram-negative bacteria

In recent years there has been a dramatic increase in reports of glycosylation of proteins in various Gram-negative systems including Neisseria meningitidis, Neisseria gonorrhoeae, Campylobacter jejuni, Pseudomonas aeruginosa, Escherichia coli, Caulobacter crescentus, Aeromonas caviae and Helicobacter pylori. Although this growing list contains many important pathogens (reviewed by Benz and Schmidt [Mol. Microbiol. 45 (2002) 267-276]) and the glycosylations are found on proteins important in pathogenesis such as pili, adhesins and flagella the precise role(s) of the glycosylation of these proteins remains to be determined. Furthermore, the details of the glycosylation biosynthetic process have not been determined in any of these systems. The definition of the precise role of glycosylation and the mechanism of biosynthesis will be facilitated by a detailed understanding of the genes involved. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

Caracterização físico química, perfil sensorial e aceitação de morangos submetidos à irradiação

A irradiação de alimentos é um método de conservação não térmico utilizado em diferentes alimentos e em diferentes doses. Sabe-se que, dependendo da dose aplicada, esse método pode ocasionar alterações nas características físico-químicas e sensoriais, que afetam a qualidade do produto. Portanto, um dos objetivos deste estudo foi analisar o efeito da irradiação nas características físico-químicas e sensoriais de morangos irradiados. A irradiação das amostras de morango ocorreu um dia após a colheita e foi realizada no Laboratório de Radiação Gama do Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), em Belo Horizonte-MG. As doses utilizadas foram 1 kGy, 2 kGy, 3 kGy e 4 kGy e a amostra controle (0 kGy). Foram avaliados pH, acidez total titulável, sólidos solúveis, ratio (relação entre teor de sólidos solúveis e acidez total titulável), açúcares redutores, totais e não redutores, pectina, ácido ascórbico, firmeza, cor, antocianinas, compostos fenólicos e capacidade antioxidante. Para a caracterização sensorial das amostras, foi utilizado o método Perfil Descritivo Otimizado (PDO), sendo avaliados os atributos sensoriais cor, sabor adocicado, gosto ácido, firmeza e suculência, por 15 julgadores previamente selecionados. Além da caracterização sensorial, foi realizada a análise de aceitação sensorial por 60 consumidores de morango em duas sessões. A irradiação não alterou significativamente a maioria das características físico-químicas analisadas, ao comparar todas as doses empregadas, incluindo o morango controle (não irradiado); apenas a firmeza apresentou valores diferentes estatisticamente: com o aumento da dose, houve diminuição da firmeza do fruto. No PDO, as amostras diferiram quanto à cor, sabor adocicado, firmeza e suculência, sendo que a amostra controle e a amostra irradiada com 1 kGy tiveram maiores valores de firmeza e menores de suculência e sabor adocicado. Em relação à aceitação, a amostra controle e a amostra irradiada com 1 kGy não diferiram estatisticamente pelo teste Tukey a 5%, mas diferiram das amostras irradiadas com doses de 3 kGy e de 4 kGy; no entanto, a amostra irradiada a 2 kGy não diferiu de nenhuma outra dose. Foram realizados estudos de correlações entre os dados físico-químicos de pH, acidez total titulável (ATT), sólidos solúveis (SS), açúcares totais e açúcares não redutores, antocianina (método pH diferencial), pectina, firmeza instrumental, relação entre SS/ATT (ratio) e alguns parâmetros de cor (a*, b*, c* e L), e os dados do teste sensorial descritivo, ou seja, os atributos de firmeza, suculência, sabor adocicado e gosto ácido. Os resultados obtidos foram correlações significativamente positivas entre pH e ratio, sólidos solúveis e pectina, antocianinas e parâmetros de cor (a* e c*), açúcares e parâmetros de cor (b* e c*), firmeza sensorial e firmeza instrumental, suculência e sabor xvi adocicado e firmeza sensorial e gosto ácido. Já as correlações negativas foram entre acidez e ratio, sólidos solúveis e firmeza, antocianina e L*, firmeza sensorial e sabor adocicado e suculência com: firmeza instrumental, firmeza sensorial e gosto ácido. Neste trabalho, também foi realizada a caracterização físico-química e sensorial de morangos irradiados nas doses determinadas por Lima Filho et al. (2014) como sendo correspondentes ao limiar de detecção (LD) sensorial (0,405 kGy) e ao limiar de rejeição (LR) sensorial (3,6 kGy) para morangos irradiados. Além disso, foi verificada a influência da embalagem na aceitação sensorial de morangos irradiados na dose 3,6 kGy. Todas as medidas físico-químicas apresentaram pequena variação entre as amostras controle (0 kGy) e o LD e o LR. Não houve diferença significativa em relação à aceitação da amostra irradiada na ausência e na presença da embalagem, provavelmente devido ao grau de conhecimento do painel de consumidores em relação ao processo de irradiação de alimentos. Conclui-se que a irradiação é um método de conservação que pode ser utilizado em morangos, uma vez que exerce pouca influência, no período de tempo estudado, nas suas características físico-químicas e sensoriais.

Effects of growth reducer and nitrogen fertilization on morphological variables, SPAD index, interception of radiation and productivity of wheat

ABSTRACT The objective of this study was to evaluate the effect of growth reducer and nitrogen fertilization on morphological variables, SPAD index, radiation interception, and grain yield of three cultivars of wheat. The experimental design was a randomized block in factorial scheme 3x5x2, with three cultivars (Mestre, Iguaçú and Itaipú), five nitrogen doses (0, 40, 80, 120, 160 Kg ha-1), and application or no application of a growth reducer, with three replications. The following characteristics were evaluated: plant height, SPAD index, leaf area index (LAI), Global Radiation Interception (GRI) and grain yield. The Tukey test (p < 0.05) was used for the comparison between the means of cultivar and growth reducer factors, and for a regression analysis to evaluate N levels. Increasing the dose of nitrogen promotes an increase in LAI of plants of wheat crops differently among cultivars, which leads to a greater degree of global radiation interception. At doses higher or equal to 120 Kg ha-1 of nitrogen, there are significant differences in grain yield between treatments with and without the application of the growth reducer. The significant interaction between growth reducer and nitrogen dose, showed that applications of growth reducer increase the GRI at doses above and below 80 Kg ha-1 of nitrogen. Nitrogen rates of 138 and 109 Kg ha-1 are responsible for maximum grain yields of wheat, which is 4235 and 3787 Kg ha-1 with and without the use of growth reducer, respectively.

SAR determination and influence of the human head in the radiation of a mobile antenna for two different frequencies

The big proliferation of mobile communication systems has caused an increased concern about the interaction between the human body and the antennas of mobile handsets. In order to study the problem, a multiband antenna was designed, fabricated and measured to operate over two frequency sub bands 900 and 1800 MHz. After that, we simulated the same antenna, but now, in the presence of a human head model to analyze the head's influence. First, the influence of the human head on the radiation efficiency of the antenna has been investigated as a function of the distance between the head and the antenna and with the inclination of the antenna. Furthermore, the relative amount of the electromagnetic power absorbed in the head has been obtained.

Influence of the Human Head in the Radiation of a Mobile Antenna

The big proliferation of mobile communication systems has caused an increased concern about the interaction between the human body and the antennas of mobile handsets. In order to study the problem, a multiband antenna was designed, fabricated and measured to operate over two frequency sub bands 900 and 1800 MHz. After that, we simulated the same antenna, but now, in the presence of a human head model to analyze the head's influence. First, the influence of the human head on the radiation efficiency of the antenna has been investigated as a function of the distance between the head and the antenna and with the inclination of the antenna. Furthermore, the relative amount of the electromagnetic power absorbed in the head has been obtained. In this study the electromagnetic analysis has been performed via FDTD (Finite Difference Time Domain).

Alternative regimens for prostate cancer treatment using radiation therapy

Purpose/Objective: The purpose of this work was to determine biologically equivalent alternative regimens for the treatment of prostate cancer using External Beam Radiotherapy (EBRT) and Low Dose-Rate Brachytherapy (LDRBT) with 125I implants and to evaluate the sensitivity of these regimens to different sets of radiobiological parameters of the Linear-Quadratic (LQ) model.

Radiographers and radiation protection: education, training and CPD

The increasing use of ionizing radiation for medical purposes emphasizes the concern about safety and justification of using ionizing radiation. This is linked with the use of new and high-dose X-ray technology (particularly CT). According to the UNSCEAR 2010 Report the total number of diagnostic medical examinations (both medical and dental) is estimated to have risen from 2.4 billion (period 1991–1996) to 3.6 billion (period 1997– 2008) - a marked increase in collective doses. An appropriate use of technology aiming diagnostic or therapy and respecting the ALARA principle is a mandatory requisite to safely perform any radiological procedure. Radiation protection is thus, a concern of all specialists in the radiology field ( radiologists, radiographers, medical physicists, among other professional groups). The importance of education and training of these professionals in reducing patients’ doses while maintaining the desired level of quality in medical exposures, as well as precise therapeutic treatments is well recognized. Education, training and continuing professional development (CPD) constitute a triad pointing towards the radiographers’ development of competences in the radiation protection field. This presentation excludes the radiographer role and competences in the fields of ultrasonography and MRI.

Negative modulation of human osteoclastogenesis by antiepileptic drugs

Bone is constantly being molded and shaped by the action of osteoclasts and osteoblasts. A proper equilibrium between both cell types metabolic activities is required to ensure an adequate skeletal tissue structure, and it involves resorption of old bone and formation of new bone tissue. It is reported that treatment with antiepileptic drugs (AEDs) can elicit alterations in skeletal structure, in particular in bone mineral density. Nevertheless, the knowledge regarding the effects of AEDs on bone cells are still scarce, particularly on osteoclastic behaviour. In this context, the aim of this study was to investigate the effects of five different AEDs on human osteoclastic cells. Osteoclastic cell cultures were established from precursor cells isolated from human peripheral blood, and were maintained in the absence (control) or in the presence of 10-8-10-4 M of different AEDs (valproate, carbamazepine, gabapentin, lamotrigine and topiramate). Cell cultures were characterized throughout a 21-day period for tartrate-resistant acid phosphatase (TRAP) activity, number of TRAP+ multinucleated cells, presence of cells with actin rings and expressing vitronectin and calcitonin receptors, and apoptosis rate. Also, the involvement of several signaling pathways on the cellular response was addressed. All the tested drugs were able to affect osteoclastic cell development, although with different profiles on their osteoclastogenic modulation properties. Globally, the tendency was to inhibit the process. Furthermore, the signaling pathways involved in the process also seemed to be differentially affected by the AEDs, suggesting that the different drugs may affect osteoclastogenesis through different mechanisms. In conclusion, the present study showed that the different AEDs had the ability to negatively modulate the osteoclastogenesis process, shedding new light towards a better understanding of how these drugs can affect bone tissue.