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PubMed2001

On-site characterization of humic-rich hydrocolloids and their metal loading by means of mobile size-fractionation and exchange techniques.

Humic-rich hydrocolloids and their metal loading in selected German bog-waters have been characterized by a novel on-site approach. By use of an on-line multistage ultrafiltration (MST-UF) unit equipped with conventional polyethersulfone (PES)-based flat membranes (nominal cut-off 0.45, 0.22, and 0.1 microm, or 100, 50, 10, 5, 3 kDa) the hydrocolloids could be fractionated on-site in both sub-particulate and macromolecular size ranges. Characterization (dissolved organic carbon (DOC), metals) of the colloid fractions obtained this way was performed off-site by use of conventional instrumental methods (carbon analyzer, AAS, ICP-OES, and TXRF (total reflection X-ray fluorescence)). Major DOC fractions of the hydrocolloids studied were found to be in the size range <5 kDa. The assessed metals (Al, Cu, Fe, Mn, Pb, and Zn) were, however, predominantly enriched in the macromolecular and sub-particulate range, depending on the metal and the sample, respectively. In addition, metal species bound to these hydrocolloids were kinetically characterized on-site by use of competitive ligand (EDTA (ethylenediaminetetraacetate)) and metal (Cu(II)) exchange; the EDTA complexes formed and the metal ions exchanged were separated by means of a small time-controlled tangential-flow UF unit (cut-off 1 kDa). Bound metal fractions, in particular Al and Fe, reacted only slowly (500 to 1000 min) with EDTA; the conditional availability was 60-99%, depending on the hydrocolloid. In contrast, the Cu(II) exchange of colloid-bound metal species approached equilibrium within 5-10 min, with characteristic exchange constants, Kex, of the order of 0.01 to 90 for the metals (Fe<Al<Zn<Mn approximately/= Ca approximately/= Mg). The results were clearly dependent on the water investigated. Thus detailed information on the conditional kinetic and thermodynamic stability of colloid-bound metal species could be obtained from competitive EDTA and Cu(II) exchange under on-site conditions.

Chelating Agents↗

PubMed2001

A new monoclonal antibody ELISA for detection and characterization of C-telopeptide fragments of type I collagen in urine.

Clinical studies have shown that measurements of urine concentration of degradation products of C-terminal telopeptides of type I collagen provide a selective marker to assess bone resorption. Assays for C-telopeptide fragments have been described using antibodies generated against an eight amino acid synthetic peptide EKAHDGGR. In this study, we describe development of a rat monoclonal antibody against a synthetic linear peptide, DFSFLPQPPQEKAHDGGR, which we isolated and characterized from Paget's urine by chromatographic methods. An ELISA procedure was developed to evaluate the efficacy of this monoclonal to measure bone resorption and characterize urinary degradation products of C-terminal type I collagen. The measuring range of ELISA was 10-1,000 ng/ml with a detection limit of 10 ng/ml. Averaged intraassay and interassay CVs were <7% (n = 8) and <11% (n = 3), respectively. Mean spike and dilution recoveries range between 90 and 116%. In assessing the clinical performance, we observed approximately 48% higher values for postmenopausal patients (n = 20) compared with premenopausal women (n= 19), Z score = 2.7 (P = 0.0091). The discriminatory power to assess subtle changes in bone turnover between pre- and postmenopausal women compares well with the commercially available markers of bone resorption. Comparison of C-telopeptide concentration in a population including normal and osteoporotic patients (n = 74) shows a strong correlation with DPYR r = 0.95 (P < 0.001). In addition, in postmenopausal osteoporotic patients, a 44% (P < 0.05) decrease in C-telopeptide concentration was observed after 3 months of treatment with Alendronate, as compared with basal values. The antibody developed in this study displays a slightly different epitope than that reported previously using eight amino acid residues EKAHDGGR. In addition, isolation and characterization of circulating forms of C-telopeptide from healthy children by immunoaffinity purification revealed the presence of two novel urinary fragments corresponding to amino acid sequence EKAHDGGR and EKAHDG, in addition to the previously known two fragments composed of two alpha-1 chains linked together by a pyridinium crosslinks. The origin of the fragment EKAHDG could not be explained by the known mechanisms involved in collagen degradation, indicating that it could be a product of renal handling of C-telopeptide fragments generated from bone. The preliminary clinical data suggest that the new assay may be useful for further investigation of the clinical importance of measurement of these type I collagen degradation products.

Adolescent↗

PubMed2003

New EPR method for cellular surface characterization.

An electron paramagnetic resonance (EPR)-based membrane surface characterization method is presented to detect the properties of the carbohydrate-rich part of membrane surfaces as well as carbohydrate interaction with other membrane constituents and water-soluble molecules. The proposed method relies on the spin-labeling and spectral decomposition based on spectral simulation and optimization with EPRSIM software. In order to increase the sensitivity of characterization to the carbohydrate-rich part of the membrane surface, the sucrose-contrasting approach is introduced. With this method, which was established on model membranes with glycolipids and tested on erythrocyte membrane, we were able to characterize the surface and lipid bilayer lateral heterogeneity. Additionally, some properties of the interaction between glycocalyx and lipid bilayer as well as between glycocalyx and sucrose molecules were determined. The experiments also provided some information about the anchoring and aggregation of the glycosylated molecules. According to the results, some functions of the glycosylated surface are discussed.

Algorithms↗

PubMed2006

Diffusion-weighted imaging and proton MR spectroscopy in the characterization of acute disseminated encephalomyelitis.

INTRODUCTION: Acute disseminated encephalomyelitis (ADEM) is usually a monophasic illness characterized by multiple lesions involving gray and white matter. Quantitative MR techniques were used to characterize and stage these lesions. METHODS: Eight patients (seven males and one female; mean age 19 years, range 5 to 36 years) were studied using conventional MRI (T2- and T1-weighted and FLAIR sequences), diffusion-weighted imaging (DWI) and proton magnetic resonance spectroscopy (MRS). Apparent diffusion coefficient (ADC) values and MRS ratios were calculated for the lesion and for normal-appearing white matter (NAWM). Three patients were imaged in the acute stage (within 7 days of the onset of neurological symptoms) and five in the subacute stage (after 7 days from the onset of symptoms). RESULTS: ADC values in NAWM were in the range 0.7-1.24 x 10(-3) mm/s2 (mean 0.937 +/- 0.17 mm/s2). ADC values of ADEM lesions in the acute stage were in the range 0.37-0.68 x 10(-3) mm/s2 (mean 0.56 +/- 0.16 mm/s2) and 1.01-1.31 x 10(-3) mm/s2 (mean 1.24 +/- 0.13 mm/s2) in the subacute stage. MRS ratios were obtained for all patients. NAA/Cho ratios were in the range 1.1-3.5 (mean 1.93 +/- 0.86) in the NAWM. NAA/Cho ratios within ADEM lesions in the acute stage were in the range 0.63-1.48 (mean 1.18 +/- 0.48) and 0.29-0.84 (mean 0.49 +/- 0.22) in the subacute stage. The ADC values, NAA/Cho and Cho/Cr ratios were significantly different between lesions in the acute and subacute stages (P < 0.001, P < 0.027, P < 0.047, respectively). ADC values were significantly different between lesions in the acute (P < 0.009) and subacute stages (P < 0.005) with NAWM. In addition, NAA/Cho and Cho/Cr ratios were significantly different between lesions in the subacute stage and NAWM (P < 0.006, P < 0.007, respectively). CONCLUSION: ADEM lesions were characterized in the acute stage by restricted diffusion and in the subacute stage by free diffusion and a decrease in NAA/Cho ratios. Restricted diffusion and progressive decrease in NAA/Cho ratios may help in staging the disease.

Adolescent↗

PubMed2004

Characterization of land contaminated by past heavy metal mining using geostatistical methods.

Aspects of mining operations, including production, processing, transportation, and, finally, abandoned mine workings, can undoubtedly cause varying degrees of environmental pollution and contamination. Characterization of the spatial distribution of pollutants in contaminated soil is important for risk assessment and soil remediation. This study has been carried out using both conventional statistics and geostatistical methods which are useful for site assessment, characterization, and monitoring situations where data are collected spatially. These methods are particularly suited to cases where spatial dependence structure and contour maps of contaminant concentration or other variables are needed. The aims of this paper were to determine the extent and severity of the pollution levels on land contaminated by past mining activity through using geostatistical techniques, assess sampling strategy, and interpret data for potentially contaminated land. In the study, a total of 329 soil samples was collected at 1-, 5-, and 10-m regular grid intervals of 100 x 1 00-m area of Carsington Pasture in the UK and analyzed using an automatic X-ray fluorescence machine for a large number of elements. Only a few elements (Cu, Pb, Zn, and Ba) were subsequently studied in detail because of their association with the mining operation. Directional and omnidirectional experimental semivariograms of elements Cu, Pb, Zn, and Ba for 10-m grid intervals, pooled data of 10- and 5-m grid intervals (S10+5), and pooled data of 10-, 5-, and 1-m grid interval (S10+5+1) showed that neither geometric nor zonal anisotropy exits in the data. The most evident spatial dependence structure of the continuity for omnidirectional experimental semivariogram, characterized by a spherical model, of each element was obtained for the pooled data set of S10+5. Pooling 1-m grid data to S10+5 shaded the spatial dependence structure. The spherical model adopted for each element embodied no nugget effect, indicating that mineralization did not occur as nuggets in the study area, but it did show different ranges of influence and sill values. Spherical semivariogram model of each element for the pooled data set of S10+5 passed the cross validation tests. Graphs of cross validation test results proved that the isotropic spherical model, with its parameters and kriging search parameters, is representative for the area under study. The values of 10,000 grid nodes established regularly over the study area were estimated by kriging interpolation technique to smooth out the contours. Kriged maps for the Cu, Pb, Zn, and Ba elements were plotted. Anomalies such as bull's-eyes and drift did not observed in the maps generated. Contour maps of estimated element concentrations revealed the extent and severity of contamination. Spatial distribution maps of the elements might be used in the remediation studies and help decision-makers and others involved in the abandoned heavy metal mining site in the UK.

Data Interpretation, Statistical↗

PubMed2006

Isolation and characterization of a MHC class II DRB locus in the European water vole (Arvicola terrestris).

In so-called model species, such as human and mouse, genes of the major histocompatibility complex (MHC) are characterized by extremely high levels of polymorphism, and it is considered that such diversity is maintained by balancing selection. ;There is now a recognized need to expand studies into nonmodel species to examine whether high MHC diversity is mirrored in natural populations, and to determine the ecological, ethological, and evolutionary processes that underpin balancing selection. To address such issues, a necessary prerequisite is the ability to characterize diversity at a single, expressed, polymorphic MHC locus on which selection may be acting. Here, we provide the first description of allelic diversity at exon 2 of an MHC class II DRB locus in the European water vole (Arvicola terrestris), characterize variation across four natural populations, and test whether the patterns of variation are consistent with the effects of balancing selection. Using single-strand conformation polymorphism analysis and subsequent DNA sequencing of gel excisions, five DRB alleles were resolved, each with a unique amino acid sequence, among 100 individuals from four geographically distinct populations. Reverse transcription polymerase chain reaction confirmed that the alleles were products from an expressed locus. Intra-allelic amino acid differences were high (10.5-33.3%), and the nonsynonymous substitution rate exceeded the synonymous substitution rate for the functional peptide-binding region (d (N):d (S)=3.91 and P<0.005). Phylogenetic comparison of resolved alleles with closely related homologues indicated that each allele represented a unique lineage preserved across speciation events. These results indicate that balancing selection has maintained diversity of DRB allelic lineages and amino acid function over evolutionary time scales, but may be less effective at preserving alleles in contemporary populations where stochastic microevolutionary processes may dominate.

Alleles↗

PubMed2000

Characterization of three isotypes of immunoglobulin light chains and T-cell antigen receptor alpha in zebrafish.

The zebrafish (Danio rerio) has become a significant model for understanding the developmental regulation of gene expression and holds considerable potential for characterizing the development of the immune system. Using a number of different approaches, including heterologous hybridization and short-primer PCR, cDNAs for three different classes of light-chain genes were identified and characterized. The zebrafish light chains are similar to trout type 1, trout type 2, and catfish type F, respectively. T-cell antigen receptor alpha (TCRalpha) was also identified and characterized. A high proportion of unusual transcripts including sterile transcripts, germline VJC transcripts, aberrant splice forms, and V-V transcripts were encountered in the immunoglobulin and TCR cDNAs examined. The light-chain and TCRalpha loci each consist of multiple families of V gene segments, apparent even from the small numbers of cDNAs of each isotype sequenced. The gene sequences reported provide an essential set of markers of both B- and T-cell lineages that will facilitate investigations of immune system development.

Amino Acid Sequence↗

PubMedDate not supplied

Specificity of SPIO particles for characterization of liver hemangiomas using MRI.

We investigated the specificity of superparamagnetic iron oxide (SPIO)-enhanced T1-weighted spin-echo (SE) magnetic resonance (MR) images for the characterization of liver hemangiomas. When imaging liver hemangiomas, which are the most frequent benign liver tumors, a method with very high specificity is required, which will obviate other studies, follow-up, or invasive diagnostic procedures such as percutaneous biopsy. Eighty-three lesions were examined by MR imaging at 1.5 T before and after intravenous injection of SPIO particles. Lesions were categorized as follows according to the final diagnosis: 37 hemangiomas, nine focal nodular hyperplasias (FNHs), 19 hepatocellular carcinomas (HCCs), and 18 metastases. Their signal intensity values were normalized to muscle and compared. The only lesions showing a significant increase in signal intensity ratio (lesion to muscle) on postcontrast T1-weighted SE images were hemangiomas (p < 0.001). The signal intensity ratio of hemangiomas increased on average by 70%. Based on receiver operating characteristic analysis and using a cutoff level of 50% signal increase, the specificity and sensitivity of SPIO-enhanced MR imaging for the characterization of hemangiomas would be 100% and 70%, respectively. The T1 effect of SPIO particles can help differentiate hemangiomas from other focal liver lesions such as FNHs, HCCs, and metastases and may obviate biopsy. When using SPIO particles for liver imaging, it is useful to add a T1-weighted sequence to T2-weighted images, thereby providing additional information for lesion characterization.

Adult↗

PubMedDate not supplied

Hepatic MR imaging: comparison of RARE derived sequences with conventional sequences for detection and characterization of focal liver lesions.

BACKGROUND: We compared two T2-weighted turbo spin echo (TSE) sequences with a T2-weighted conventional SE (CSE) sequence to determine whether sequences derived from rapid acquisition with relaxation enhancement such as TSE could replace CSE for the detection and subsequent characterization of focal liver lesions. METHODS: A total of 55 consecutive patients with 107 liver lesions underwent magnetic resonance imaging examinations at 1.5 Tesla, with a constant imaging protocol. TSE pulse sequences were acquired with eight echo trains (repetition time [TR], 4718 ms; echo time [TE], 90 ms; acquisition time [TA], 4.03 min; and a symmetric k-space ordering scheme) and 11 echo trains (TR, 4200 ms; TE, 140 ms; TA, 4.40 min; and an asymmetric k-space ordering scheme) and compared with CSE (TR, 2300 ms; TE, 45/90 ms; TA, 9.53 min). Images were analyzed qualitatively by scoring image quality and artifacts and counting focal liver lesions by independent reading with consensus obtained for discrepancies. Quantitative analysis was performed by measuring signal-to-noise (S/N), contrast-to-noise (C/N), and tumor-liver signal intensity (T/L) ratios. RESULTS: T2-weighted TSE sequences provided better subjective image quality and reduced artifacts as compared with the T2-weighted CSE sequence. CSE and TSE sequences exhibited no statistically significant differences in liver S/N, lesion-liver C/N (CSE TE, 90 ms: 18.6 +/- 14.0; TSE TE, 90 ms: 16.5 +/- 12.9) and the detectability of focal liver lesions. Heavily T2-weighted TSE with a TE of 140 ms allowed correct characterization of focal liver lesions based on a T/L ratio of 3.0 in 84% of patients. CONCLUSIONS: T2-weighted TSE sequences are as suited as CSE for the detection (TE, 90 ms), and appear to be superior for the characterization (TE, 140 ms), of focal hepatic lesions. Whether a single sequence, such as a double-echo TSE or a single-echo TSE sequence with a TE between 110 and 120 ms, might perform both functions as well or better than CSE is unknown. However, because of time savings, TSE eventually may be preferred over CSE.

Artifacts↗

PubMed2006

Characterization of hypoechoic focal hepatic lesions in patients with fatty liver: diagnostic performance and confidence of contrast-enhanced ultrasound.

The objective of this study was to assess the diagnostic performance of contrast-enhanced ultrasound (CEUS) to characterize hypoechoic focal hepatic lesions (HFHL) in fatty liver (FL). A study group of 105 patients with FL and 105 HFHLs (52 malignant and 53 benign) underwent CEUS after SonoVue administration. Two blinded readers independently reviewed baseline ultrasound (US) and CEUS scans and classified each lesion as malignant or benign on a five-point scale of confidence, and recorded whether further imaging work-up was needed. Sensitivity, specificity, areas under the receiver operating characteristic (ROC) curve (A (z)), and interobserver agreement were calculated. We observed that the diagnostic confidence improved after reviewing CEUS scans for both readers (A (z)=0.706 and 0.999 and A (z)=0.665 and 0.990 at baseline US and CEUS, respectively; p<0.0001). Inter-reader agreement increased (weighted k=0.748 at baseline US vs. 0.882 at CEUS). For both readers, after CEUS, the occurrence of correctly characterized lesions increased (from 27/105 [27.5%] to 94/105 [89.5%], and from 19/105 [18.1%] to 93/105 [88.6%], respectively; p<0.0001) and the need for further imaging decreased (from 93/105 [88.6%] to 26/105 [24.8%], and from 96/105 [91.4%] to 40/105 [38.1%], respectively; p<0.0001). We conclude that CEUS improves the diagnostic performance of radiologists in the characterization of HFHLs in FL and reduces the need for further imaging work-up.

Adenoma, Liver Cell↗

PubMed2006

Characterization of focal liver lesions: comparative study of contrast-enhanced ultrasound versus spiral computed tomography.

The purpose of this study was to compare the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) with spiral computed tomography (SCT) for the characterization of focal liver lesions (FLL) and to determine the degree of correlation between the two techniques. Seventy-seven FLL (45 hepatocellular carcinomas; 12 metastases; ten hemangiomas; two regenerating/dysplastic nodules; eight focal nodular hyperplasias) detected with ultrasound (US) were prospectively evaluated by CEUS using a second-generation contrast agent and SCT (with an interval of no more than one month between the two techniques). Independent observers made the most probable diagnosis and the results were compared with the final diagnoses (histology n = 59; MRI n = 18). Statistical analysis was performed by the Chi-square and Kappa tests. CEUS provided a correct, specific diagnosis in 69/77 (90%) of the FLL, while SCT did so in 67/77 (87%). The sensitivity, specificity, and diagnostic accuracy for malignancy were 91%, 90%, and 91%, respectively, for CEUS and 88%, 89%, and 88%, respectively, for SCT. No statistically significant difference was found between CEUS and SCT in the characterization of FLL (p > 0.05). In addition, agreement between the two imaging techniques was good (k = 0.75). We conclude that CEUS and SCT provide a similar diagnostic accuracy in the characterization of FLL, with a good degree of correlation between the two techniques.

Contrast Media↗

PubMed2000

Regional characterization of a hamster-sheep somatic cell hybrid panel.

The regional characterization of a previously obtained hamster-sheep hybrid panel is reported. Using data available from ruminant maps (sheep, cattle, and goat), we have selected a set of 300 markers and have analyzed them by PCR in this hybrid panel. Results obtained for 204 markers show the presence of all sheep chromosomes (including gonosomes) in entire or fragmented form. Analysis of syntenies has given 130 types of answer defining segments of variable sizes. This study has led to the regional characterization of this panel and provides comparative data on a set of bovine and caprine markers. With the level of characterization now achieved for this hybrid panel, the regional assignment of new genes or markers to sheep chromosomes can be rapidly obtained. Finally, this panel will help to collect new data for comparative mapping of domestic animals and to highlight the conservation of syntenic groups between closely related species, that is, sheep, cattle, and goat.

Animals↗

PubMed2004

Clinical characterization of the prostatitis patient in Italy: a prospective urology outpatient study.

A prospective multi-center Italian urology outpatient survey, undertaken to determine the prevalence of prostatitis in Italy, provided an ideal opportunity to identify and characterize the typical prostatitis patient presenting to Italian urologists. A total of 70 urologists, representing a cross section of urologic centers in Italy, counted and recorded the overall total male patients reported in the clinic and the overall total patients diagnosed with prostatitis over a 5 week period in late 2001. Data on demographics, previous diagnoses, symptoms (frequency and severity), quality of life, physical examination and laboratory data were prospectively collected. A total of 1,148 patients were identified with prostatitis (12.8%). Of these, 1,074 patients had complete data and could be included in this characterization analysis. The mean age of the prostatitis patients was 47.1 years (range 16-83); two thirds had experienced their first symptom within the last year. A family history of prostatitis was reported by 20.4%. The most common urinary diseases were benign prostatic hyperplasia (17.4%), recurrent urinary tract infection (11.2%) and urinary calculogenesis (11.1%), while the most common concurrent diseases were diabetes (7.2%) and depression (6.8%). The most frequently reported and most severe symptoms at the time of evaluation were irritative voiding symptoms, perineal and suprapubic pain and discomfort. Over three quarters of the patients were dissatisfied with their quality of life. Bacteria were cultured in 15.6%, 17.7% and 14.0% of expressed prostatic secretions, urine specimens after prostatic massage and semen specimens, respectively. Prostatitis is a common outpatient diagnosis, comprising over 10% of male outpatient visits to urologists in Italy. This comprehensive characterization of the typical prostatitis patient diagnosed in routine urological outpatient practice can be employed to generate hypothesis-driven studies in diagnosis and treatment.

Adult↗

PubMed2002

Hemodialysis improves myocardial interstitial edema and left ventricular diastolic function in patients with end-stage renal disease: noninvasive assessment by ultrasonic tissue characterization.

Congestive heart failure is the most common cause of mortality in patients with end-stage renal disease (ESRD). Ultrasonic tissue characterization with integrated backscatter offers a promising method for the noninvasive assessment of regional myocardial contractile performance and fibrosis. The aim of this study was to investigate the effect of hemodialysis (HD) on myocardial tissue characterization and left ventricular function in ESRD patients. We examined 26 patients with ESRD undergoing routine HD (age 63 +/- 12 years, duration of HD 9.2 +/- 3.2 years) and 30 patients with essential hypertension (HT; 60 +/- 10 years). Routine echocardiographic parameters and the cyclic variation of ultrasonic integrated backscatter of the ventricular septum (CV-IBS) were measured. Left ventricular mass index was significantly larger in patients with ESRD than in those with HT (217 +/- 56 vs 146 +/- 45 g/m(2), P < 0.05). The indices for left ventricular diastolic function (E/A, the ratio of left ventricular peak early to late diastolic filling velocity; DT, the deceleration time of the early diastolic filling) and CV-IBS had deteriorated significantly in patients with ESRD before HD compared with those with HT (E/A, 0.6 +/- 0.2 vs 0.9 +/- 0.3, P < 0.05; DT, 228 +/- 23 vs 184 +/- 19 ms, P < 0.05; CV-IBS, 9.0 +/- 1.3 vs 12.4 +/- 0.9 dB, P < 0.05), possibly reflecting interstitial fibrosis. In patients with ESRD, HD reduced calculated left ventricular mass index by 19% (before HD, 217 +/- 56 vs immediately after HD, 176 +/- 45 g/m(2), P < 0.05) and CV-IBS by 19% (9.0 +/- 1.3 vs 7.3 +/- 1.1 dB, P < 0.05), that possibly reflected improvement of interstitial edema. HD also significantly improved indices for left ventricular diastolic function (E/A, 0.6 +/- 0.2 vs 0.9 +/- 0.2, P < 0.05; DT, 228 +/- 23 vs 188 +/- 21 ms, P < 0.05). HD improves myocardial interstitial edema and left ventricular diastolic function in patients with ESRD. Noninvasive assessment of ultrasonic tissue characterization is useful in defining the pathophysiological changes of ventricular myocardium in patients with ESRD.

Diastole↗

PubMed2001

Telomeres in Chironomus thummi are characterized by different subfamilies of complex DNA repeats.

Members of the genus Chironomus, as well as other Diptera, lack the highly conserved structure of most telomeres, characterized by short repeats generated by telomerase, and have long repeats at their chromosome ends. Among Chironomus species with characterized telomeres Chironomus thummi is of particular interest because one of the telomeres, 3R, forms a giant puff in response to heat shock and other stress treatments. The puff contains nucleoprotein granules in which transcripts of the telomeric repeats are present. Most other nontelocentric telomeres irregularly form less pronounced heat shock puffs. One, the 4R telomere is, however, exceptional in being completely refractory to heat shock. We now pose the question whether the repeats in 3R and 4R have special sequence features. We find three different subfamilies of telomeric repeats in C. thummi, named TsA, TsB and TsC. They have an identical length (176 bp) and display base differences in defined regions, V1 and V2, connected by conserved segments. The TsA subfamily is localized exclusively at 3R, TsC only at 4R, whereas TsB repeats are shared by the remaining nontelocentric telomeres: 1R, 1L, 2R, 2L and 3L. Consequently both 3R and 4R have unique types of telomeric repeats. The 176 bp type repeats are absent from the telocentric, left end of chromosome 4. These results allowed us to differentiate in polytene chromosomes four types of telomeres characterized by tandemly repeated specific sequences.

Animals↗

PubMed2002

Ethylmalonic encephalopathy: further clinical and neuroradiological characterization.

Ethylmalonic encephalopathy (EE) is a rare metabolic disorder with an autosomal recessive mode of inheritance that is clinically characterized by neuromotor delay, hyperlactic acidemia, recurrent petechiae, orthostatic acrocyanosis, and chronic diarrhea. Increased urinary levels of ethylmalonic acid and methylsuccinic acid are the main biochemical features of the disorder. We report on two patients affected by EE who showed different clinical and neuroradiological patterns. Patient 1 presented with a chronic clinical course characterized by very slow neuromotor deterioration, ataxia, and dysarthria. In contrast, patient 2 had an acute neonatal onset with severe neuromotor retardation, severe generalized hypotonia, and intractable seizures. Neuroradiological follow-up of patient 1 detected a diffuse hyperintensity on the T2 images at the basal ganglia which remained stable during a period of four years. Patient 2, in contrast, showed a rapid process of cerebral, and in part, cerebellar atrophy. On the basis of our observations, we reviewed the data published in the literature and tried to delineate the natural history of EE, which appears to be characterized by a wide spectrum of severity in the clinical course. No reports on neuroradiological follow-up of EE patients are available in the literature with which to compare our data. Finally, both patients showed a muscle COX deficiency. The pathogenetic implications of such a biochemical finding will be also discussed.

Brain Diseases, Metabolic, Inborn↗

PubMed2006

Functional characterization of Nicotiana benthamiana homologs of peanut water deficit-induced genes by virus-induced gene silencing.

Determining the functional role of genes that are differentially regulated during a stress response is challenging. In this study, few water deficit-induced genes from peanut were characterized in Nicotiana benthamiana using virus-induced gene silencing (VIGS) and their relevance for stress adaptation was validated. Twenty-five cDNA clones from peanut water deficit stress-induced cDNA library that had more than 50% nucleotide similarity with N. benthamiana or tomato homologs were selected. VIGS in peanut is not yet feasible and therefore we characterized these 25 genes in N. benthamiana. Increased membrane damage was seen under water deficit stress in most of the silenced plants signifying that many of these stress-induced genes are important to confer drought tolerance. Among the genes tested, silencing by homolog of flavonol 3-O-glucosyltransferase (F3OGT), homolog of alcohol dehydrogenase, homologous to salt inducible protein, and homolog of heat shock protein 70 showed more visible wilting symptoms compared with the control plants during water deficit stress. Interestingly, down-regulation of two genes, homologous to aspartic proteinase 2, and homolog of Jumonji class of transcription factor showed relative drought tolerant phenotypes. F3OGT silenced plants showed more wilting symptoms, membrane damage and chlorophyll degradation than any other silenced plants during water deficit. Our results demonstrate that VIGS approach can be used to characterize and assess the functional relevance of water deficit stress-induced cDNAs in a heterologous species.

Anthocyanins↗

PubMed2006

Identification and characterization of genes expressed in early embryogenesis from microspores of Brassica napus.

To understand the mechanism in induction of embryogenesis from microspores of Brassica napus, we isolated exhaustively the genes expressed differentially during the early stage of microspore culture. A subtracted cDNA library composed of up-regulated genes during androgenic initiation was produced by suppression subtractive hybridization followed by differential screening by dot blot hybridization, and a total of 136 non-redundant expressed sequence tags were identified. Analysis of the potential functions of the genes showed that 64% of these genes were homologous to known genes, and the remaining ones have not been previously reported to participate in embryogenesis. Many embryo-specific genes were contained in the isolated genes, for example, genes cording lipid transfer protein, napin, cruciferin, oleosin, and phytosulfokine. Real-time RT-PCR analysis for 15 selected genes, which are understood to not be related with embryogenesis, demonstrated that all genes were expressed highly in the early stage of microspore embryogenesis. A few genes also showed higher expression in microspores cultured in non-embryogenic condition or in later stages of embryos. A principal component analysis based on expression profiles of the 15 genes demonstrated that these genes were classified into 2 groups, one characterized by their high expression in initiation of embryogenesis, and the other characterized by their expression in the early to middle stage of embryogenesis. The expressions of these genes were confirmed in zygotic embryos. The identification and characterization of the genes isolated in the present study provide novel information on microspore embryogenesis in Brassica.

Brassica napus↗