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1.
Tech Coloproctol ; 24(12): 1301-1306, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32648140

RESUMO

BACKGROUND: Chronic non-healing wounds are a major problem after closed incision pilonidal surgery. Freshly collected autologous adipose tissue injected into perianal fistulas in patients with Crohn's disease seems to promote healing. We investigated this technique in patients with non-healing wounds after cleft-lift surgery for pilonidal sinus disease (PSD). METHOD: In a prospective interventional pilot study conducted at our institution autologous adipose tissue from the abdominal wall was harvested, and injected into chronic non-healing PS wounds after surgical revision, healing rate being the primary outcome. The wounds were left open. Patients were followed every 2 to 3 weeks until complete healing (skin coverage, no undermining). RESULTS: 7 male patients were included (mean age 24 ± 0,6 SD years) and complete healing was achieved in 6 patients (86%). Median time to healing was 90 days (range 36-403 days ) and mean follow-up time was 388± 45 days. All patients reported major symptom relief shortly after the procedure. The mean operation time was 80 ± 23 minutes and the mean amount of freshly collected adipose tissue injected was 27.4± 12 ml. There were no complications. CONCLUSIONS: Freshly collected autologous adipose tissue injected into chronic non-healing pilonidal wounds seems safe and efficient.


Assuntos
Seio Pilonidal , Tecido Adiposo , Adulto , Humanos , Masculino , Seio Pilonidal/cirurgia , Projetos Piloto , Estudos Prospectivos , Resultado do Tratamento , Adulto Jovem
3.
J Clin Virol ; 105: 49-56, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29886373

RESUMO

BACKGROUND: The current treatment options for hepatitis C virus (HCV), based on direct acting antivirals (DAA), are dependent on virus genotype and previous treatment experience. Treatment failures have been associated with detection of resistance-associated substitutions (RASs) in the DAA targets of HCV, the NS3, NS5A and NS5 B proteins. OBJECTIVE: To develop a next generation sequencing based method that provides genotype and detection of HCV NS3, NS5A, and NS5 B RASs without prior knowledge of sample genotype. STUDY DESIGN: In total, 101 residual plasma samples from patients with HCV covering 10 different viral subtypes across 4 genotypes with viral loads of 3.84-7.61 Log IU/mL were included. All samples were de-identified and consequently prior treatment status for patients was unknown. Almost full open reading frame amplicons (∼ 9 kb) were generated using RT-PCR with a single primer set. The resulting amplicons were sequenced with high throughput sequencing and analysed using an in-house developed script for detecting RASs. RESULTS: The method successfully amplified and sequenced 94% (95/101) of samples with an average coverage of 14,035; four of six failed samples were genotype 4a. Samples analysed twice yielded reproducible nucleotide frequencies across all sites. RASs were detected in 21/95 (22%) samples at a 15% threshold. The method identified one patient infected with two genotype 2b variants, and the presence of subgenomic deletion variants in 8 (8.4%) of 95 successfully sequenced samples. CONCLUSIONS: The presented method may provide identification of HCV genotype, RASs detection, and detect multiple HCV infection without prior knowledge of sample genotype.


Assuntos
Farmacorresistência Viral/genética , Técnicas de Genotipagem , Hepacivirus/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Fases de Leitura Aberta , Proteínas não Estruturais Virais/genética , Variação Genética , Genótipo , Hepatite C/sangue , Humanos , Filogenia , Análise de Sequência de DNA
4.
Virol J ; 14(1): 231, 2017 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-29166950

RESUMO

BACKGROUND: Aleutian mink disease has major economic consequences on the mink farming industry worldwide, as it causes a disease that affects both the fur quality and the health and welfare of the mink. The virus causing this disease is a single-stranded DNA virus of the genus Amdoparvovirus belonging to the family of Parvoviridae. In Denmark, infection with AMDV has largely been restricted to a region in the northern part of the country since 2001, affecting only 5% of the total Danish mink farms. However, in 2015 outbreaks of AMDV were diagnosed in all parts of the country. Initial analyses revealed that the out breaks were caused by two different strains of AMDV that were significant different from the circulating Danish strains. To track the source of these outbreaks, a major investigation of global AMDV strains was initiated. METHODS: Samples from 13 different countries were collected and partial NS1 gene was sequenced and subjected to phylogenetic analyses. RESULTS: The analyses revealed that AMDV exhibited substantial genetic diversity. No clear country wise clustering was evident, but exchange of viruses between countries was revealed. One of the Danish outbreaks was caused by a strain of AMDV that closely resembled a strain originating from Sweden. In contrast, we did not identify any potential source for the other and more widespread outbreak strain. CONCLUSION: To the authors knowledge this is the first major global phylogenetic study of contemporary AMDV partial NS1 sequences. The study proved that partial NS1 sequencing can be used to distinguish virus strains belonging to major clusters. The partial NS1 sequencing can therefore be a helpful tool in combination with epidemiological data, in relation to outbreak tracking. However detailed information on farm to farm transmission requires full genome sequencing.


Assuntos
Vírus da Doença Aleutiana do Vison/classificação , Doença Aleutiana do Vison/virologia , Vison , Filogenia , Proteínas não Estruturais Virais/genética , Doença Aleutiana do Vison/epidemiologia , Vírus da Doença Aleutiana do Vison/genética , Criação de Animais Domésticos , Animais , Sequência de Bases , DNA Viral , Dinamarca/epidemiologia , Surtos de Doenças , Variação Genética/genética , Análise de Sequência de DNA/veterinária
5.
Virol J ; 14(1): 119, 2017 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-28637462

RESUMO

BACKGROUND: Aleutian Mink Disease (AMD) is an infectious disease of mink (Neovison vison) and globally a major cause of economic losses in mink farming. The disease is caused by Aleutian Mink Disease Virus (AMDV) that belongs to the genus Amdoparvovirus within the Parvoviridae family. Several strains have been described with varying virulence and the severity of infection also depends on the host's genotype and immune status. Clinical signs include respiratory distress in kits and unthriftiness and low quality of the pelts. The infection can also be subclinical. Systematic control of AMDV in Danish mink farms was voluntarily initiated in 1976. Over recent decades the disease was mainly restricted to the very northern part of the country (Northern Jutland), with only sporadic outbreaks outside this region. Most of the viruses from this region have remained very closely related at the nucleotide level for decades. However, in 2015, several outbreaks of AMDV occurred at mink farms throughout Denmark, and the sources of these outbreaks were not known. METHODS: Partial NS1 gene sequencing, phylogenetic analyses data were utilized along with epidemiological to determine the origin of the outbreaks. RESULTS: The phylogenetic analyses of partial NS1 gene sequences revealed that the outbreaks were caused by two different clusters of viruses that were clearly different from the strains found in Northern Jutland. These clusters had restricted geographical distribution, and the variation within the clusters was remarkably low. The outbreaks on Zealand were epidemiologically linked and a close sequence match was found to two virus sequences from Sweden. The other cluster of outbreaks restricted to Jutland and Funen were linked to three feed producers (FP) but secondary transmissions between farms in the same geographical area could not be excluded. CONCLUSION: This study confirmed that partial NS1 sequencing can be used in outbreak tracking to determine major viral clusters of AMDV. Using this method, two new distinct AMDV clusters with low intra-cluster sequence diversity were identified, and epidemiological data helped to reveal possible ways of viral introduction into the affected herds.


Assuntos
Vírus da Doença Aleutiana do Vison/classificação , Vírus da Doença Aleutiana do Vison/genética , Doença Aleutiana do Vison/epidemiologia , Surtos de Doenças , Técnicas de Genotipagem , Análise de Sequência de DNA , Proteínas não Estruturais Virais/genética , Vírus da Doença Aleutiana do Vison/isolamento & purificação , Animais , Dinamarca/epidemiologia , Epidemiologia Molecular , Filogenia
6.
Scand J Immunol ; 85(3): 182-190, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28109028

RESUMO

Oncogenic human papillomaviruses (HPVs) are in most cases eliminated by intervention of T cells. As many other pathogens, these oncogenic HPVs belong to an ancient and diverse virus family. Therefore, we found it relevant to investigate the potential and limitations of inducing a broad response-either by inducing cross-reactive T cells or by administering a polyvalent vaccine. To test these strategies, we designed three ancestral and two circulating sequences based on the two domains of the E1 and E2 proteins of papillomaviruses (PVs) that exhibit the highest degree of conservation in comparison with the other PV proteins. The PV sequences were fused to a T cell adjuvant, the murine invariant chain and encoded in a recombinant adenoviral vector which was administered to naïve outbred mice. By measuring T cell responses induced by these different vaccines and towards peptide pools representing three circulating strains and a putative ancestor of oncogenic HPVs, we showed that the ancestral vaccine antigen has to be approximately 90% identical to the circulating PVs before a marked drop of ~90% mean CD8+ T cell responses ensues. Interestingly, the combination of two or three type-specific PV vaccines did not induce a significant decrease in the CD8+ T cell response to the individual-targeted PV types. Polyvalent HPV vaccine based on the E1 and E2 proteins seem to be capable of triggering responses towards more than one type of PV while the cross-reactivity of ancestral vaccine seems insufficient in consideration of the sequence diversity between HPV types.


Assuntos
Antígenos Virais/imunologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Proteínas de Ligação a DNA/imunologia , Proteínas Oncogênicas Virais/imunologia , Papillomaviridae/genética , Papillomaviridae/imunologia , Vacinas contra Papillomavirus/imunologia , Adenoviridae/genética , Adenoviridae/imunologia , Sequência de Aminoácidos , Animais , Antígenos Virais/genética , Feminino , Imunização , Camundongos , Proteínas Recombinantes de Fusão/imunologia , Homologia de Sequência de Aminoácidos
7.
J Clin Microbiol ; 43(3): 1099-104, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15750068

RESUMO

We characterized the G and P types from 162 rotavirus-positive stool specimens collected from 162 persons in Denmark (134 children and 28 adults) with acute diarrhea in 1998, 2000, and 2002. Samples were obtained during outpatient consultations (73%) and from hospitalized patients (27%). Although more than 20 different G-P combinations were identified, only 52% represented the globally most common types G1P[8], G2P[4], and G4P[8]. The G9 genotype, which is emerging worldwide, was identified in 12% of all samples. Twenty-one percent of the samples were of mixed genotypic origin, which is the highest frequency reported in any European population. The standard reverse transcription-PCR methods initially failed to identify a considerable fraction of the rotavirus P strains due to mutations at the VP4 primer-binding sites of P[8] strains. The application of a degenerate P[8] primer resulted in typing of most VP4 strains. There was considerable year-to-year variation among the circulating G-P types, and whereas G1P[8] was predominant in 1998 (42% of samples) and 2002 (26%), G2P[4] was the strain that was most frequently detected in 2000 (26% of samples). Our findings might implicate challenges for rotavirus vaccine implementation in a European population and underscore the importance of extensive strain surveillance prior to, during, and after introduction of any vaccine candidate.


Assuntos
Proteínas do Capsídeo/genética , Infecções por Rotavirus/virologia , Rotavirus/classificação , Adolescente , Adulto , Idoso , Sequência de Bases , Criança , Pré-Escolar , Feminino , Genótipo , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Vírus Reordenados
8.
Virology ; 311(1): 125-33, 2003 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-12832210

RESUMO

Among 167 rotavirus specimens collected from young children in a suburban area of Bissau, Guinea-Bissau, from 1996 to 1998, most identifiable strains belonged to the uncommon P[6], G2 type and approximately 50% remained incompletely typed. In the present study, 76 such strains were further characterized. Due to interprimer interaction during the standard multiplex PCR approach, modifications of this procedure were implemented. The modified analyses revealed a high frequency of G2, G8, and G9 genotypes, often combined with P[4] and/or P[6]. The Guinean G8 and G9 strains were 97 and 98%, respectively, identical to other African G8 and G9 strains. Multiple G and/or P types were identified at a high frequency (59%), including two previously undescribed mixed infections, P[4]P[6], G2G8 and P[4]P[6], G2G9. These mixed infections most likely represent naturally occurring reassortance of rotavirus strains. Detection of such strains among the previously incompletely typed strains indicates a potential underestimation of mixed infections, if only a standard multiplex PCR procedure is followed. Furthermore cross-priming of the G3 primer with the G8 primer binding site and silent mutations at the P[4] and P[6] primer binding sites were detected. These findings highlight the need for regular evaluation of the multiplex primer PCR method and typing primers. The high frequency of uncommon as well as reassortant rotavirus strains in countries where rotavirus is an important cause of child mortality underscores the need for extensive strain surveillance as a basis to develop appropriate rotavirus vaccine candidates.


Assuntos
Antígenos Virais , Infecções por Rotavirus/epidemiologia , Rotavirus/genética , Proteínas do Capsídeo/genética , Pré-Escolar , Genótipo , Guiné-Bissau/epidemiologia , Humanos , Dados de Sequência Molecular , Filogenia , RNA Viral/genética , Rotavirus/classificação , Homologia de Sequência
9.
Bioinformatics ; 17(3): 237-48, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11294789

RESUMO

MOTIVATION: The primary function of DNA is to carry genetic information through the genetic code. DNA, however, contains a variety of other signals related, for instance, to reading frame, codon bias, pairwise codon bias, splice sites and transcription regulation, nucleosome positioning and DNA structure. Here we study the relationship between the genetic code and DNA structure and address two questions. First, to which degree does the degeneracy of the genetic code and the acceptable amino acid substitution patterns allow for the superimposition of DNA structural signals to protein coding sequences? Second, is the origin or evolution of the genetic code likely to have been constrained by DNA structure? RESULTS: We develop an index for code flexibility with respect to DNA structure. Using five different di- or tri-nucleotide models of sequence-dependent DNA structure, we show that the standard genetic code provides a fair level of flexibility at the level of broad amino acid categories. Thus the code generally allows for the superimposition of any structural signal on any protein-coding sequence, through amino acid substitution. The flexibility observed at the level of single amino acids allows only for the superimposition of punctual and loosely positioned signals to conserved amino acid sequences. The degree of flexibility of the genetic code is low or average with respect to several classes of alternative codes. This result is consistent with the view that DNA structure is not likely to have played a significant role in the origin and evolution of the genetic code.


Assuntos
DNA/química , DNA/genética , Conformação de Ácido Nucleico , Aminoácidos , Proteínas de Bactérias/genética , DNA Bacteriano/química , Repetições de Dinucleotídeos , Escherichia coli/genética , Evolução Molecular , Análise de Sequência de DNA , Repetições de Trinucleotídeos
10.
Br J Surg ; 88(2): 200-5, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11167866

RESUMO

BACKGROUND: Laparoscopy in patients with a clinical suspicion of acute appendicitis has not gained wide acceptance, and its use remains controversial. METHODS: In a randomized controlled trial of laparoscopic versus open appendicectomy, 583 of 828 consecutive patients consented to participate. Three hundred and one patients were allocated to open appendicectomy and 282 patients to laparoscopy, 65 of whom required conversion to open appendicectomy. Length of stay in hospital was the primary endpoint, while operating time, postoperative morbidity, duration of convalescence and cosmesis were secondary endpoints. RESULTS: Intention-to-treat analysis revealed an equally short hospital stay in the two groups (median 2 days). The median time to return to normal activity (7 versus 10 days) and work (10 versus 16 days) was significantly shorter following laparoscopy. Laparoscopy was associated with fewer wound infections (P < 0.03) and improved cosmesis (P < 0.001), but the operating time was longer (60 versus 40 min). Laparoscopy was associated with more intraperitoneal abscesses (5 versus 1 per cent) but, adjusted for a greater number of gangrenous or perforated appendices in this group, the difference failed to reach statistical significance. CONCLUSION: Hospital stay was equally short, whereas laparoscopic appendicectomy was associated with fewer wound infections, faster recovery, earlier return to work and improved cosmesis.


Assuntos
Apendicectomia/métodos , Apendicite/cirurgia , Laparoscopia/métodos , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Humanos , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento
11.
Biotechnol Bioeng ; 70(3): 300-12, 2000 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-10992234

RESUMO

It is well known that high-viscosity fermentation broth can lead to mixing and oxygen mass transfer limitations. The seemingly obvious solution for this problem is to increase agitation intensity. In some processes, this has been shown to damage mycelia, affect morphology, and decrease product expression. However, in other processes increased agitation shows no effect on productivity. While a number of studies discuss morphology and fragmentation at the laboratory and pilot scale, there are relatively few publications available for production-scale fungal fermentations. The goal of this study was to assess morphology and fragmentation behavior in large-scale, fed-batch, fungal fermentations used for the production of protein. To accomplish this, a recombinant strain of Aspergillus oryzae was grown in 80 m(3) fermentors at two different gassed, impeller power-levels (one 50% greater than the other). Impeller power is reported as energy dissipation/circulation function (EDCF) and was found to have average values of 29.3 +/- 1.0 and 22.0 +/- 0.3 kW m(-3) s(-1) at high and low power levels, respectively. In all batches, biomass concentration profiles were similar and specific growth rate was < 0.03 h(-1). Morphological data show hyphal fragmentation occurred by both shaving-off of external clump hyphae and breakage of free hyphae. The fragmentation rate constant (k(frag)), determined using a first-order model, was 5.90 and 5.80 h(-1) for high and low power batches, respectively. At the end of each batch, clumps accounted for only 25% of fungal biomass, most of which existed as small, sparsely branched, free hyphal elements. In all batches, fragmentation was found to dominate fungal growth and branching. We speculate that this behavior was due to slow growth of the culture during this fed-batch process.


Assuntos
Aspergillus oryzae/crescimento & desenvolvimento , Aspergillus oryzae/metabolismo , Reatores Biológicos , Biomassa , Biotecnologia , Fermentação , Cinética
12.
J Mol Biol ; 299(4): 907-30, 2000 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-10843847

RESUMO

We have performed a computational analysis of DNA structural features in 18 fully sequenced prokaryotic genomes using models for DNA curvature, DNA flexibility, and DNA stability. The structural values that are computed for the Escherichia coli chromosome are significantly different from (and generally more extreme than) that expected from the nucleotide composition. To aid this analysis, we have constructed tools that plot structural measures for all positions in a long DNA sequence (e.g. an entire chromosome) in the form of color-coded wheels (http://www.cbs.dtu. dk/services/GenomeAtlas/). We find that these "structural atlases" are useful for the discovery of interesting features that may then be investigated in more depth using statistical methods. From investigation of the E. coli structural atlas, we discovered a genome-wide trend, where an extended region encompassing the terminus displays a high of level curvature, a low level of flexibility, and a low degree of helix stability. The same situation is found in the distantly related Gram-positive bacterium Bacillus subtilis, suggesting that the phenomenon is biologically relevant. Based on a search for long DNA segments where all the independent structural measures agree, we have found a set of 20 regions with identical and very extreme structural properties. Due to their strong inherent curvature, we suggest that these may function as topological domain boundaries by efficiently organizing plectonemically supercoiled DNA. Interestingly, we find that in practically all the investigated eubacterial and archaeal genomes, there is a trend for promoter DNA being more curved, less flexible, and less stable than DNA in coding regions and in intergenic DNA without promoters. This trend is present regardless of the absolute levels of the structural parameters, and we suggest that this may be related to the requirement for helix unwinding during initiation of transcription, or perhaps to the previously observed location of promoters at the apex of plectonemically supercoiled DNA. We have also analyzed the structural similarities between groups of genes by clustering all RNA and protein-encoding genes in E. coli, based on the average structural parameters. We find that most ribosomal genes (protein-encoding as well as rRNA genes) cluster together, and we suggest that DNA structure may play a role in the transcription of these highly expressed genes.


Assuntos
DNA Bacteriano/química , DNA Bacteriano/genética , Escherichia coli/genética , Genoma Bacteriano , Conformação de Ácido Nucleico , Proteínas de Bactérias/genética , Pareamento de Bases/genética , Cor , Biologia Computacional , Simulação por Computador , Cristalografia por Raios X , DNA Super-Helicoidal/química , DNA Super-Helicoidal/genética , Desoxirribonuclease I/metabolismo , Genes Bacterianos/genética , Modelos Moleculares , Nucleossomos/química , Nucleossomos/genética , Reconhecimento Automatizado de Padrão , Filogenia , Maleabilidade , Regiões Promotoras Genéticas/genética , RNA Bacteriano/genética , Software , Estatística como Assunto , Termodinâmica
13.
Comput Chem ; 23(3-4): 191-207, 1999 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-10404615

RESUMO

Computational prediction of eukaryotic promoters from the nucleotide sequence is one of the most attractive problems in sequence analysis today, but it is also a very difficult one. Thus, current methods predict in the order of one promoter per kilobase in human DNA, while the average distance between functional promoters has been estimated to be in the range of 30-40 kilobases. Although it is conceivable that some of these predicted promoters correspond to cryptic initiation sites that are used in vivo, it is likely that most are false positives. This suggests that it is important to carefully reconsider the biological data that forms the basis of current algorithms, and we here present a review of data that may be useful in this regard. The review covers the following topics: (1) basal transcription and core promoters, (2) activated transcription and transcription factor binding sites, (3) CpG islands and DNA methylation, (4) chromosomal structure and nucleosome modification, and (5) chromosomal domains and domain boundaries. We discuss the possible lessons that may be learned, especially with respect to the wealth of information about epigenetic regulation of transcription that has been appearing in recent years.


Assuntos
Regiões Promotoras Genéticas , Cromossomos , Ilhas de CpG , DNA/genética , Metilação de DNA , Células Eucarióticas , Humanos , Sequências Reguladoras de Ácido Nucleico , Transcrição Gênica
14.
Bioinformatics ; 15(11): 918-29, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10743558

RESUMO

MOTIVATION: Over a dozen major degenerative disorders, including myotonic distrophy, Huntington's disease and fragile X syndrome, result from unstable expansions of particular trinucleotides. Remarkably, only some of all the possible triplets, namely CAG/CTG, CGG/CCG and GAA/TTC, have been associated with the known pathological expansions. This raises some basic questions at the DNA level. Why do particular triplets seem to be singled out? What is the mechanism for their expansion and how does it depend on the triplet itself? Could other triplets or longer repeats be involved in other diseases? RESULTS: Using several different computational models of DNA structure, we show that the triplets involved in the pathological repeats generally fall into extreme classes. Thus, CAG/CTG repeats are particularly flexible, whereas GCC, CGG and GAA repeats appear to display both flexible and rigid (but curved) characteristics depending on the method of analysis. The fact that (1) trinucleotide repeats often become increasingly unstable when they exceed a length of approximately 50 repeats, and (2) repeated 12-mers display a similar increase in instability above 13 repeats, together suggest that approximately 150 bp is a general threshold length for repeat instability. Since this is about the length of DNA wrapped up in a single nucleosome core particle, we speculate that chromatin structure may play an important role in the expansion mechanism. We furthermore suggest that expansion of a dodecamer repeat, which we predict to have very high flexibility, may play a role in the pathogenesis of the neurodegenerative disorder multiple system atrophy (MSA). CONTACT: pfbaldi@ics.uci.edu, yves@netid.com, brunak@cbs.dtu.dk, gorm@cbs.dtu.dk.


Assuntos
Simulação por Computador , Doenças Genéticas Inatas/genética , Modelos Genéticos , Atrofia de Múltiplos Sistemas/genética , Expansão das Repetições de Trinucleotídeos/genética , Antecipação Genética , Proteínas de Transporte/genética , DNA/química , DNA/genética , DNA/metabolismo , Desoxirribonuclease I/metabolismo , Humanos , Proteínas do Tecido Nervoso/genética , Conformação de Ácido Nucleico , Nucleossomos/genética , Nucleossomos/metabolismo , Maleabilidade , Ligação Proteica/genética , Repetições de Trinucleotídeos/genética
15.
Artigo em Inglês | MEDLINE | ID: mdl-9783207

RESUMO

We study from a computational standpoint several different physical scales associated with structural features of DNA sequences, including dinucleotide scales such as base stacking energy and propeller twist, and trinucleotide scales such as bendability and nucleosome positioning. We show that these scales provide an alternative or complementary compact representation of DNA sequences. As an example we construct a strand invariant representation of DNA sequences. The scales can also be used to analyze and discover new DNA structural patterns, especially in combinations with hidden Markov models (HMMs). The scales are applied to HMMs of human promoter sequences revealing a number of significant differences between regions upstream and downstream of the transcriptional start point. Finally we show, with some qualifications, that such scales are by and large independent, and therefore complement each other.


Assuntos
DNA/química , Inteligência Artificial , Sequência de Bases , DNA/genética , Humanos , Cadeias de Markov , Estrutura Molecular , Oligodesoxirribonucleotídeos/química , Oligodesoxirribonucleotídeos/genética , Reconhecimento Automatizado de Padrão , Regiões Promotoras Genéticas , TATA Box , Termodinâmica
16.
FEBS Lett ; 433(1-2): 98-102, 1998 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-9738941

RESUMO

Classical heme-containing plant peroxidases have been ascribed a wide variety of functional roles related to development, defense, lignification, and hormonal signaling. More than 40 peroxidase genes are now known in Arabidopsis thaliana for which functional association is complicated by a general lack of peroxidase substrate specificity. Computational analysis was performed on 30 near full-length Arabidopsis peroxidase cDNAs for annotation of start codons and signal peptide cleavage sites. A compositional analysis revealed that 23 of the 30 peroxidase cDNAs have 5' untranslated regions containing 40-71% adenine, a rare feature observed also in cDNAs which predominantly encode stress-induced proteins, and which may indicate translational regulation.


Assuntos
Arabidopsis/enzimologia , Peroxidase/genética , Adenina/análise , Sequência de Aminoácidos , Arabidopsis/genética , Códon , DNA Complementar/química , Dados de Sequência Molecular , Peroxidase/química , Peroxidase/metabolismo , Poli A/metabolismo , Biossíntese de Proteínas , Sinais Direcionadores de Proteínas/química , Sinais Direcionadores de Proteínas/metabolismo , RNA Mensageiro/química , RNA Mensageiro/metabolismo , Especificidade por Substrato
17.
J Mol Biol ; 281(4): 663-73, 1998 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-9710538

RESUMO

The fact that DNA three-dimensional structure is important for transcriptional regulation begs the question of whether eukaryotic promoters contain general structural features independently of what genes they control. We present an analysis of a large set of human RNA polymerase II promoters with a very low level of sequence similarity. The sequences, which include both TATA-containing and TATA-less promoters, are aligned by hidden Markov models. Using three different models of sequence-derived DNA bendability, the aligned promoters display a common structural profile with bendability being low in a region upstream of the transcriptional start point and significantly higher downstream. Investigation of the sequence composition in the two regions shows that the bendability profile originates from the sequential structure of the DNA, rather than the general nucleotide composition. Several trinucleotides known to have high propensity for major groove compression are found much more frequently in the regions downstream of the transcriptional start point, while the upstream regions contain more low-bendability triplets. Within the region downstream of the start point, we observe a periodic pattern in sequence and bendability, which is in phase with the DNA helical pitch. The periodic bendability profile shows bending peaks roughly at every 10 bp with stronger bending at 20 bp intervals. These observations suggest that DNA in the region downstream of the transcriptional start point is able to wrap around protein in a manner reminiscent of DNA in a nucleosome. This notion is further supported by the finding that the periodic bendability is caused mainly by the complementary triplet pairs CAG/CTG and GGC/GCC, which previously have been found to correlate with nucleosome positioning. We present models where the high-bendability regions position nucleosomes at the downstream end of the transcriptional start point, and consider the possibility of interaction between histone-like TAFs and this area. We also propose the use of this structural signature in computational promoter-finding algorithms.


Assuntos
DNA/química , Regiões Promotoras Genéticas/genética , RNA Polimerase II/genética , Algoritmos , Humanos , Cadeias de Markov , Conformação de Ácido Nucleico , Nucleossomos/química , Nucleotídeos/química , Análise de Sequência de DNA
18.
Semin Oncol ; 24(2 Suppl 7): S7-64-S7-68, 1997 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9194483

RESUMO

Gemcitabine is a novel nucleoside analogue with a unique mechanism of action. In light of its good single-agent activity in several solid tumors, generally mild toxicity profile, and potential for synergy, combination phase I studies with other active chemotherapeutic agents have been conducted. In two studies the combination of gemcitabine and carboplatin was used to treat patients with non-small cell lung cancer. Gemcitabine was administered weekly x 3 every 4 weeks, and carboplatin was given on day 1. Although dose-limiting myelotoxicity was observed, encouraging activity was noted. In other studies patients with recurrent or persistent ovarian cancer or with refractory solid tumors were treated with weekly gemcitabine and paclitaxel on a 28-day schedule or with both drugs given every 2 weeks. Dose escalation was possible and toxicities were manageable. The effect of sequence of drug administration on the toxicity profile was also examined. Further trials to establish the efficacy of these promising approaches as well as combinations of all three drugs are needed.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Ovarianas/tratamento farmacológico , Antimetabólitos Antineoplásicos/administração & dosagem , Antimetabólitos Antineoplásicos/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Carboplatina/administração & dosagem , Carboplatina/efeitos adversos , Desoxicitidina/administração & dosagem , Desoxicitidina/efeitos adversos , Desoxicitidina/análogos & derivados , Feminino , Humanos , Masculino , Paclitaxel/administração & dosagem , Paclitaxel/efeitos adversos , Ribonucleotídeo Redutases/antagonistas & inibidores , Gencitabina
19.
Artigo em Inglês | MEDLINE | ID: mdl-9322041

RESUMO

Translation in eukaryotes does not always start at the first AUG in an mRNA, implying that context information also plays a role. This makes prediction of translation initiation sites a non-trivial task, especially when analysing EST and genome data where the entire mature mRNA sequence is not known. In this paper, we employ artificial neural networks to predict which AUG triplet in an mRNA sequence is the start codon. The trained networks correctly classified 88% of Arabidopsis and 85% of vertebrate AUG triplets. We find that our trained neural networks use a combination of local start codon context and global sequence information. Furthermore, analysis of false predictions shows that AUGs in frame with the actual start codon are more frequently selected than out-of-frame AUGs, suggesting that our networks use reading frame detection. A number of conflicts between neural network predictions and database annotations are analysed in detail, leading to identification of possible database errors.


Assuntos
Expressão Gênica , Genoma , Redes Neurais de Computação , Iniciação Traducional da Cadeia Peptídica , Sequência de Aminoácidos , Angiotensinogênio/genética , Animais , Sítios de Ligação/genética , Códon de Iniciação/genética , Bases de Dados Factuais , Células Eucarióticas , Estudos de Avaliação como Assunto , Genoma Humano , Humanos , Dados de Sequência Molecular , Sinais Direcionadores de Proteínas/genética
20.
Ugeskr Laeger ; 158(19): 2697-9, 1996 May 06.
Artigo em Dinamarquês | MEDLINE | ID: mdl-8744070

RESUMO

The purpose of this research project was to examine, in retrospect, the effect of certain factors on the incidence of the use of restrains before and after the introduction of the Danish law reform concerning compulsory treatment. Data concerning the use of restraints on four locked wards in the Psychiatric Department of Glostrup Hospital during a six-month period in 1988 were compared with equivalent data from a six-month period in 1991. It was found that the law reform had no statistically significant influence on the incidence of the use of restraints. Factors such as high bed occupancy rate and shortage of staff did not lead to a higher incidence of use of restraint.


Assuntos
Internação Compulsória de Doente Mental , Isolamento de Pacientes , Restrição Física , Internação Compulsória de Doente Mental/legislação & jurisprudência , Internação Compulsória de Doente Mental/estatística & dados numéricos , Dinamarca , Feminino , Humanos , Masculino , Isolamento de Pacientes/legislação & jurisprudência , Isolamento de Pacientes/estatística & dados numéricos , Restrição Física/legislação & jurisprudência , Estudos Retrospectivos
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