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A Devos

Publications and source records attributed to A Devos.

At least 19 recordsLinked to original sources
PubMed2006

Individual and collective vibrational modes of nanostructures studied by picosecond ultrasonics.

We report on picosecond ultrasonic measurements obtained on aluminum and platinum nanostructures with variable dot size and lateral periodicity which realized a 2D phononic crystal. Performing investigations at different resolution scales, we have identified individual modes of vibration depending on the dot size, and mode of vibration strongly correlated with the bi-dimensional organization. The platinum dots sputtered on an aluminum layer have shown a behavior of isolated oscillators without any coupling between neighbor elements in this phononic crystal. The frequency of such normal modes, extracted from time resolved measurements are in good agreement with 3D finite element simulations. In contrast, with aluminum dot systems where the coupling is more efficient we observe a complex spectrum of vibrational modes related to the band structure induced by the bi-dimensional patterning.

Algorithms↗
PubMed2005

The use of multivariate MR imaging intensities versus metabolic data from MR spectroscopic imaging for brain tumour classification.

This study investigated the value of information from both magnetic resonance imaging and magnetic resonance spectroscopic imaging (MRSI) to automated discrimination of brain tumours. The influence of imaging intensities and metabolic data was tested by comparing the use of MR spectra from MRSI, MR imaging intensities, peak integration values obtained from the MR spectra and a combination of the latter two. Three classification techniques were objectively compared: linear discriminant analysis, least squares support vector machines (LS-SVM) with a linear kernel as linear techniques and LS-SVM with radial basis function kernel as a nonlinear technique. Classifiers were evaluated over 100 stratified random splittings of the dataset into training and test sets. The area under the receiver operating characteristic (ROC) curve (AUC) was used as a global performance measure on test data. In general, all techniques obtained a high performance when using peak integration values with or without MR imaging intensities. For example for low- versus high-grade tumours, low- versus high-grade gliomas and gliomas versus meningiomas, the mean test AUC was higher than 0.91, 0.94, and 0.99, respectively, when both MR imaging intensities and peak integration values were used. The use of metabolic data from MRSI significantly improved automated classification of brain tumour types compared to the use of MR imaging intensities solely.

Brain Chemistry↗
PubMed2004

Brain tumor classification based on long echo proton MRS signals.

There has been a growing research interest in brain tumor classification based on proton magnetic resonance spectroscopy (1H MRS) signals. Four research centers within the EU funded INTERPRET project have acquired a significant number of long echo 1H MRS signals for brain tumor classification. In this paper, we present an objective comparison of several classification techniques applied to the discrimination of four types of brain tumors: meningiomas, glioblastomas, astrocytomas grade II and metastases. Linear and non-linear classifiers are compared: linear discriminant analysis (LDA), support vector machines (SVM) and least squares SVM (LS-SVM) with a linear kernel as linear techniques and LS-SVM with a radial basis function (RBF) kernel as a non-linear technique. Kernel-based methods can perform well in processing high dimensional data. This motivates the inclusion of SVM and LS-SVM in this study. The analysis includes optimal input variable selection, (hyper-) parameter estimation, followed by performance evaluation. The classification performance is evaluated over 200 stratified random samplings of the dataset into training and test sets. Receiver operating characteristic (ROC) curve analysis measures the performance of binary classification, while for multiclass classification, we consider the accuracy as performance measure. Based on the complete magnitude spectra, automated binary classifiers are able to reach an area under the ROC curve (AUC) of more than 0.9 except for the hard case glioblastomas versus metastases. Although, based on the available long echo 1H MRS data, we did not find any statistically significant difference between the performances of LDA and the kernel-based methods, the latter have the strength that no dimensionality reduction is required to obtain such a high performance.

Artificial Intelligence↗
PubMed2004

Classification of brain tumours using short echo time 1H MR spectra.

The purpose was to objectively compare the application of several techniques and the use of several input features for brain tumour classification using Magnetic Resonance Spectroscopy (MRS). Short echo time 1H MRS signals from patients with glioblastomas (n = 87), meningiomas (n = 57), metastases (n = 39), and astrocytomas grade II (n = 22) were provided by six centres in the European Union funded INTERPRET project. Linear discriminant analysis, least squares support vector machines (LS-SVM) with a linear kernel and LS-SVM with radial basis function kernel were applied and evaluated over 100 stratified random splittings of the dataset into training and test sets. The area under the receiver operating characteristic curve (AUC) was used to measure the performance of binary classifiers, while the percentage of correct classifications was used to evaluate the multiclass classifiers. The influence of several factors on the classification performance has been tested: L2- vs. water normalization, magnitude vs. real spectra and baseline correction. The effect of input feature reduction was also investigated by using only the selected frequency regions containing the most discriminatory information, and peak integrated values. Using L2-normalized complete spectra the automated binary classifiers reached a mean test AUC of more than 0.95, except for glioblastomas vs. metastases. Similar results were obtained for all classification techniques and input features except for water normalized spectra, where classification performance was lower. This indicates that data acquisition and processing can be simplified for classification purposes, excluding the need for separate water signal acquisition, baseline correction or phasing.

Brain Chemistry↗
PubMed2002

Evaluation of a commercial line probe assay for identification of mycobacterium species from liquid and solid culture.

The performance of a commercial line probe assay (LiPA) (Inno-LiPA Mycobacteria; Innogenetics, Belgium) for the detection and identification of Mycobacterium species from liquid and solid culture was evaluated at five routine clinical laboratories. The LiPA method is based on the reverse hybridization principle, in which the mycobacterial 16S-23S ribosomal RNA (rRNA) spacer region is amplified by polymerase chain reaction (PCR). Amplicons are subsequently hybridized with oligonucleotide probes arranged on a membrane strip and detected by a colorimetric system. The test detects the presence of Mycobacterium species and specifically identifies Mycobacterium tuberculosis complex, Mycobacterium kansasii, Mycobacterium xenopi, Mycobacterium gordonae, Mycobacterium avium complex, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium scrofulaceum, and Mycobacterium chelonae - Mycobacterium abscessus complex. The results of LiPA were compared with the results obtained using traditional biochemical and molecular tests (DNA probe-based techniques, PCR restriction enzyme analysis of the 65 kDa heat-shock protein gene, and sequencing of the 16S rDNA). A total of 669 isolates, 642 of which were identified as Mycobacterium species and 27 as non- Mycobacterium species, were tested by LiPA. After analysis of 14 initially discordant results and exclusion of one isolate, concordant results were obtained for 636 of 641 Mycobacterium isolates (99.2% accuracy). All Mycobacterium species reacted with the MYC ( Mycobacterium species) probe (100% sensitivity), and all non- Mycobacterium species were identified as such (100% specificity).

Bacterial Typing Techniques↗
PubMed2001

Evidence of laser-wavelength effect in picosecond ultrasonics: possible connection with interband transitions.

We have studied the effect of wavelength change on picosecond acoustic pulses generated using a femtosecond laser. For the first time, we show that the pulse shape can be strongly influenced by the laser wavelength. The results are in excellent agreement with a calculation based on a thermoelastic model which connects them to significant changes in the piezo-optical constants. There are similarities between the present study and stress modulation spectroscopy, which allows us to ascribe the observations to interband transitions and suggests thus a new potentiality of picosecond ultrasonics.

Journal Article↗
PubMed1999

Leptomeningeal metastases from ethmoid sinus adenocarcinoma: clinico-radiological correlation.

A patient with sinonasal adenocarcinoma is presented with leptomeningeal metastases affecting multiple cranial nerves and spinal nerve roots. Head and neck cancer is known to be an extremely rare source for leptomeningeal metastatic spread. The cranial nerves, the spinal cord and roots and the cerebral hemispheres can be affected in case of leptomeningeal metastatic spread. Examination of the CSF is the hallmark of the diagnosis if leptomeningeal metastatic spread is suspected, but this case illustrates that the combination of specific clinical features on one hand and specific lesions on the Gd-enhanced T1-weighted MRI study on the other hand is reliable enough to make a presumed diagnosis if the CSF analysis remains negative. We suggest that in our patient direct leptomeningeal spread occurred through the cribriform plate to the CSF, followed by further spread in a gravity dependent way.

Adenocarcinoma↗
PubMed1997

A randomized phase II study of BB-10010: a variant of human macrophage inflammatory protein-1alpha for patients receiving high-dose etoposide and cyclophosphamide for malignant lymphoma and breast cancer.

Macrophage inflammatory protein-1alpha (MIP-1alpha) is a chemokine that can inhibit the cell cycle progression of both primitive haemopoietic and epidermal progenitor cells. This property could potentially be exploited to attenuate both the myelosuppressive effects of chemotherapy as well as mucositis. We evaluated both the biological and clinical effects of BB-10010, a genetically engineered variant of MIP-1alpha, in patients with malignant lymphoma or breast cancer receiving high-dose etoposide (VP 3.6 g/m2) and cyclophosphamide (Cy 200 mg/kg). 52 patients were randomized to one of three cohorts. Cohort A received no BB-10010; cohorts B and C received 10 microg/kg and 100 microg/kg of BB-10010, respectively. All patients received post-chemotherapy G-CSE BB-10010 was well tolerated. There were no significant differences between groups in recovery to an ANC > 0.5 x 10(9)/l, 1 x 10(9)/l or 1.5 x 10(9)/l, the number of days with an ANC < 0.5 x 10(9)/l, days to a platelet count > 50 x 10(9)/l or 100 x 10(9)/l, or the incidence and severity of mucositis. There was no evidence of any effect of BB-10010 on colony-forming cell (CFC) or long-term culture-initiating cell (LTC-IC) mobilization, cycling activity in the marrow or on chemotherapy-induced changes in CFC or LTC-IC number both of which were in the normal range by 22 d after completion of the chemotherapy. To our knowledge this is the first report of a myelointensive regimen having no apparent long-term effect on the LTC-IC compartment. In summary, BB-10010 is safe when used in patients receiving high-dose therapy but has no effect on reducing the toxicity of such therapy.

Adolescent↗
PubMed1997

Identification of a functional androgen-response element in the exon 1-coding sequence of the cystatin-related protein gene crp2.

Two hormone-responsive segments, one in the region of the promoter and one in intron 1, are identified in two homologous androgen-regulated and differentially expressed rat genes encoding the cystatin-related proteins (CRPs). Footprint analysis with the androgen receptor (AR) DNA-binding domain on the promoter-containing fragments reveals an AR-binding site downstream of the transcription start point in the crp2 gene (ARBSd/crp2, +40/+63). It displays an androgen response element-like sequence motif 5'-AGAAGAaaaTGTACA-3' and overlaps with the ATG translation start codon. A double-stranded oligonucleotide containing this sequence forms a DNA-protein complex with the full-length AR synthesized by vaccinia, as seen in band shift assays. Additional AR-binding sites, ARBSu/crp1 and ARBSu/crp2, occur 5' upstream of the transcription start point and are located at an identical position (-142/ -120) in crp1 and crp2. The AR affinity for these two slightly different sequence motifs is relatively weak. The biological function of all three AR-binding sites as transcription control elements has been studied. The ARBSd/crp2 element clearly shows androgen-response element characteristics. The contribution of the common upstream element to the androgen-dependent control of reporter gene transcription is less clear. The transcription of a reporter gene construct containing the crp2 footprint fragment crp2F (-273/+88) is hormonally regulated as determined by transfection into the human breast cancer cell line T-47D. Androgens, but also glucocorticoids, efficiently stimulate steroid-dependent transcription of the chloramphenicol acetyltransferase gene. Mutation of the 5'-TGTACA-3' sequence in ARBSd/crp2 destroys the AR binding and abolishes the androgen-dependent synthesis of chloramphenicol acetyltransferase. A large fragment derived from intron 1 of the crp1 and crp2 gene can also provide the androgen-dependent transcription of chimeric constructs in T-47D cells. However, the induction measured is less than the one observed with crp2F (-273/+88), and this activity seems to reside in several subfragments that each display a low but consistent androgen responsiveness.

Androgens↗
PubMed1996

The androgen-specific probasin response element 2 interacts differentially with androgen and glucocorticoid receptors.

The nuclear receptors constitute a large family of transcription factors characterized by a well conserved DNA-binding domain. The receptors for glucocorticoids, progestins, mineralocorticoids, and androgens constitute a subgroup because they bind in vitro with high affinity to DNA elements containing a partial palindrome of the core sequence 5'-TGTTCT-3'. In vivo, however, the corresponding steroids differentially regulate the expression of their target genes, even when more than one receptor type is present in a particular cell. The DNA-binding domains of the androgen and of the glucocorticoid receptors bind most androgen response elements with similar relative affinities. In contrast, one element (5'-GGTTCTTGGAGTACT-3') which was recently described in the promoter region of the probasin gene selectively interacts with the DNA-binding domain of the androgen receptor and not with that of the glucocorticoid receptor. From studies with chimeric elements, it can be deduced that it is the left subsequence 5'-GGTTCT-3' which excludes the glucocorticoid receptor domain from binding. In co-transfection experiments where the ARE of the C3(1) gene is responsive to both androgens and glucocorticoids, the probasin element is induced only by androgens and not by glucocorticoids. The existence of response elements which are recognized preferentially by the androgen receptor provides yet another possible mechanism to explain the differences of the in vivo effects between androgens and other steroids of the subgroup.

Androgen-Binding Protein↗
PubMed1996

Androgens transcriptionally regulate the expression of cystatin-related protein and the C3 component of prostatic binding protein in rat ventral prostate and lacrimal gland.

In this report, it is demonstrated that the C3 component of prostatic binding protein (PBP) is also expressed and androgen regulated in the exorbital lacrimal gland, as shown previously for cystatin-related protein (CRP), another abundant secretory protein from the ventral prostate. The presence of C3 messenger RNA (mRNA) could be demonstrated by both Northern blot hybridization and PCR amplification and sequencing. The mRNAs encoding the C1 and C2 components of PBP, however, were undetectable. At the protein level, the C3 component in the lacrimal gland is glycosylated and linked by disulfide bridges to a new 10-kDa component not reacting with the PBP antiserum. As shown previously for CRP, the expression of C3 in the lacrimal gland requires the simultaneous presence of androgens and a functional androgen receptor. The effects of castration and androgen treatment on CRP and C3 mRNA concentrations were studied by Northern blot and dot blot hybridization; effects on transcription rates were determined by nuclear run-on assay. Two days after castration, the relative abundance of CRP mRNA had declined significantly (P < 0.01) to 10.5 +/- 1.5% (+/-SEM) of precastration levels in the prostate and to 14.5 +/- 8.0% in the lacrimal gland; the transcription rates declined to 14.3% and 10.0%, respectively. The C3 mRNA level and transcription rate in the prostate showed a more moderate decrease (P < 0.05) to 40.6 +/- 8.5% and 41.7%, but were hardly measurable in the lacrimal gland. Androgen administration resulted in a rapid increase in the transcription rates, which reached or exceeded control levels after 6-9 h of treatment and clearly preceded the increase in mRNA levels. It is concluded that the lacrimal gland, which can be studied conveniently in female and long term androgen-depleted animals offers a suitable model for the study of androgen-regulated gene expression.

Analysis of Variance↗
PubMed1995

The genes coding for rat cystatin-related prostate protein (Cstrp) map to chromosome 3q41.

Two genes encoding rat cystatin-related prostate protein (Cstrp), previously called CRP (Devos et al., 1993), were mapped to chromosome 3q41 by fluorescent in situ hybridization. The results were confirmed using a panel of mouse-rat hybrids that segregate rat chromosomes. Analysis of genomic DNA indicates that the Cstrp locus comprises probably more than three very similar genes.

Animals↗
PubMed1993

Structure of rat genes encoding androgen-regulated cystatin-related proteins (CRPs): a new member of the cystatin superfamily.

Cystatin-related proteins (CRPs) are abundant androgen-regulated secretory glycoproteins that are specifically synthesized in the ventral prostate and lachrymal gland of the rat. Two complete 6-kb genes, Crp1 and Crp2, have been cloned and characterized. They are differentially expressed and encode slightly different proteins. The genes each contain four exons which are interrupted by large introns. An alignment of their sequences demonstrates an overall homology of 90%. The 3' end of a third gene, Crp3, from which only a 1.5-kb fragment was isolated, displays a sequence identity of 84%. These data indicate the existence of a Crp multigene family. The 5' flanking regions of Crp1 and Crp2 are highly homologous and contain a GATAAA sequence 29 nt upstream from the transcription start point. This TATA-box-like element is also found in the promoters of the genes encoding cystatin type-2 proteins. No other recognizable transcription control elements can be detected. Potential binding sites (ARE) for the androgen receptor are scattered throughout the entire genes. The exon/intron organization of the genes encoding CRPs, the size of the exons and their encoding amino acid sequences exhibiting a characteristic spacing of the Cys residues are structural elements displaying a remarkable similarity with the corresponding elements in the genes encoding cystatin type-2 proteins. CRPs must therefore belong to the cystatin superfamily. However, due to their additional domain encoded in an extra exon 2, CRPs must be classified as a new family, type 5.

Amino Acid Sequence↗
PubMed1993

An effect of androgens on the length of the poly(A)-tail and alternative splicing cause size heterogeneity of the messenger ribonucleic acids encoding cystatin-related protein.

The 22-kilodalton glycoprotein, expressed in the rat ventral prostate under the influence of androgens, is structurally a cystatin-related protein (CRP), as has been shown by copy DNA sequencing. In fact, two slightly different forms (CRP-1 and CRP-2) are expressed in the prostate; one of them (CRP-1) is also expressed in the exorbital lacrymal gland. In both glands, the CRP-1 messenger RNA (mRNA)s are androgen regulated. Moreover, androgens also influence the size of these mRNAs, which show marked heterogeneity (from 760-950 nucleotides). Indeed, the smaller forms are predominant in castrated animals, whereas the large forms are observed immediately after androgen induction. Hybridization with oligo(dT) followed by ribonuclease H treatment revealed that differences in length of the poly(A)-tail are responsible for this effect of androgens. Indeed, two well defined forms of CRP mRNA subsisted after removal of the poly(A)-tail by this treatment. In the less abundant shorter form (CRP-1 delta), 123 nucleotides are deleted by alternative splicing at the junction between the third and the fourth exon. The variant mRNA encodes a truncated protein, wherein the last 27 amino acids are replaced by a hydrophobic stretch of 8 amino acids. No alternative splicing was observed for the CRP-2 mRNA.

Alternative Splicing↗
PubMed1992

The 4.4-kilodalton proline-rich polypeptides of the rat ventral prostate are the proteolytic products of a 637-kilodalton protein displaying highly repetitive sequences and encoded in a single exon.

We have determined the complete sequence of the 637-kilodalton precursor for the proline-rich polypeptides (PRPs). This protein is encoded in one large exon of a single copy gene. The acidic precursor of 5761 residues comprises a signal peptide and three large domains displaying a high proline content (11-15%). The sequence of domain A (928 residues) is unique and contains several small clusters of acidic amino acids. Domain B (830 residues) exhibits seven tandem repeats, four of them displaying a strongly diverged sequence. In domain C (3914 residues) 39 units, of which only 8 are degenerate, occur in a tandem repeat. Their sequence of 100 amino acids shows a high structural similarity (76-92%) and contains all the PRP variants which are produced by specific proteolytic processing. The COOH-terminal part (35 residues) is basic. Two variant PRP-precursor alleles occur which slightly differ in the number of repeats in domain C. The high degree of sequence conservation within the repeat regions suggests that the gene presumably evolved by multiple amplification and dispersion of two internal segments. In the 5097-base pair genomic region 5' upstream from the translation start, several control elements for transcription are recognized. A potential binding site for the Sp1 factor (GGGCGG) separated by 47 nucleotides from an initiator motif, most probably elements of the promoter, is detected in the vicinity of the ATG codon. Several putative androgen response elements (TGTYCT) are found in the 5' adjacent region and far upstream two Alu type III repeats and two (CA)n repeats are located. These results provide the basis for a detailed study of the androgen-regulated and tissue-specific expression of the PRP-precursor gene.

Amino Acid Sequence↗
PubMed1987

[Virus excretion and changes in virulence of type 1 paramyxovirus of pigeons following passage through chickens].

Paramyxovirus type 1 of pigeons (strain PMV1-D) was transmitted by sequential contact over nine groups of SPF chicks. The first and last (9th) passages were made in 12-day-old SPF chicks, whereas the others were made in day-old chicks. Mortality was much higher in the last passage group than it was in the first group. None of the day-old chicks survived the PMV1-D infection. Increased virulence of PMV1-D for chickens following passages was also found to be present by the virus characterisation indexes, the EID50, the ICPI and the IVPI in particular.

Age Factors↗