A methodology for current density calculations in high-frequency RF resonators

As nuclear magnetic resonance imaging and spectroscopy move inexorably toward higher field-strength magnets in search of improved signal-to-noise ratio, spectral resolution, and spatial resolution, the way in which radiofrequency (RF) probes are designed changes. At higher frequencies, resonant cavities become the favored RF ''coil'' type and may be built using streamline elements to reduce the inductance of the system. In modeling such systems, the quasi-static approach of assuming that current flows evenly in all conductor cross sections and that adjacent conductors do not affect each other becomes less reasonable. The proximity of RF conductors in resonators typically causes RF eddy currents to flow, whereby the current density in each rung is altered by the RF fields generated by nearby conductors. The proper understanding and prediction of how resonators will perform require a model of the current densities flowing in conducting sections, including all RF eddy current effects. Very few models of this type have been presented in the literature. This article presents an overview of one such model and of how it may be applied to a variety of resonators, both shielded and unshielded, circular, and elliptical, in cross section. Results are presented from a shielded head coil operating at 2 tesla. (C) 1997 John Wiley & Sons, Inc.

Synchronization of mutually coupled chaotic systems

We report on the experimental observation of both basic frequency locking synchronization and chaos synchronization between two mutually coupled chaotic subsystems. We show that these two kinds of synchronization are two stages of interaction between coupled chaotic systems. in particular the chaos synchronization could be understood as a state of phase locking between coupled chaotic oscillations.

Frequency of 22q11.2 microdeletion in sporadic non-syndromic tetralogy of Fallot cases

Background: Tetralogy of Fallot (TOF) is a congenital conotruncal heart defect commonly found in DiGeorge (DGS) and velocardiofacial (VCFS) syndromes. The deletion of chromosome 22q11 has also been demonstrated in sporadic or familial cases of TOF. The aim of the present study was to investigate the frequency of del22q11 in patients with non-syndromic TOF seen at a tertiary Pediatric Cardiology care center. Method: One hundred and twenty three non-syndromic TOF patients were selected and evaluated by history, physical examination and review of medical records. Venous blood was drawn for genomic DNA extraction after informed consent 22q11 microdeletion diagnosis was conducted through a standardized SNP genotyping assay and consecutive homozygosity mapping. Phenotype-genotype correlations regarding cardiac anatomy were conducted. Results: We evaluated 123 non-syndromic TOF patients for a 22q11 deletion. 105 (85.4%) patients presented pulmonary stenosis and 18 (14.6%) had pulmonary atresia. Eight patients (6.5%) were found to have a deletion. Of the deleted patients, three (37.5%) presented pulmonary atresia. We have verified a tendency towards a higher prevalence of pulmonary atresia when comparing TOF patients with and without 22q11 microdeletion. Conclusions: 22q11.2 deletion in non-syndromic TOF patients is present in approximately 6% of patients. We suggest a tendency towards a higher prevalence of pulmonary atresia in non-syndromic TOF patients with 22q11 microdeletion. Molecular genetic screening of non-syndromic TOF patient may be important for the correct care of these patients and a more specific genetic diagnostic and counseling. (C) 2007 Elsevier Ireland Ltd. All rights reserved.

A high-resolution genetic map of the familial Mediterranean fever candidate region allows identification of haplotype-sharing among ethnic groups

Familial Mediterranean fever (FMF) is a recessive disorder of inflammation caused by mutations in a gene (designated MEFV) on chromosome 16p13.3, We have recently constructed a 1-Mb cosmid contig that includes the FMF critical region. Here we show genotype data for 12 markers from our physical map, including 5 newly identified microsatellites, in FMF families. Intrafamilial recombinations placed MEFV in the similar to 285 kb between D16S468/D16S3070 and D16S3376. We observed significant linkage disequilibrium in the North African Jewish population, and historical recombinants in the founder haplotype placed MEFV between D16S3082 and D16S3373 (similar to 200 kb). In smaller panels of Iraqi Jewish, Arab, and Armenian families, there were significant allelic associations only for D16S3370 and D16S2617 among the Armenians. A sizable minority of Iraqi Jewish and Armenian carrier chromosomes appeared to be derived from the North African Jewish ancestral haplotype. We observed a unique FMF haplotype common to Iraqi Jews, Arabs, and Armenians and two other haplotypes restricted to either the Iraqi Jewish or the Armenian population. These data support the view that a few major mutations account for a large percentage of the cases of FMF and suggest that same of these mutations arose before the affected Middle Eastern populations diverged from one another. (C) 1997 Academic Press.

Generation and phenotypic characterization of new human ovarian cancer cell lines with the identification of antigens potentially recognizable by HLA-restricted cytotoxic T cells

This study describes a simple method for long-term establishment of human ovarian tumor lines and prediction of T-cell epitopes that could be potentially useful in the generation of tumor-specific cytotoxic T lymphocytes (CTLs), Nine ovarian tumor lines (INT.Ov) were generated from solid primary or metastatic tumors as well as from ascitic fluid, Notably all lines expressed HLA class I, intercellular adhesion molecule-1 (ICAM-1), polymorphic epithelial mucin (PEM) and cytokeratin (CK), but not HLA class II, B7.1 (CD80) or BAGE, While of the 9 lines tested 4 (INT.Ov1, 2, 5 and 6) expressed the folate receptor (FR-alpha) and 6 (INT.Ov1, 2, 5, 6, 7 and 9) expressed the epidermal growth factor receptor (EGFR); MAGE-1 and p185(HER-2/neu) were only found in 2 lines (INT.Ov1 and 2) and GAGE-1 expression in 1 line (INT.Ov2). The identification of class I MHC ligands and T-cell epitopes within protein antigens was achieved by applying several theoretical methods including: 1) similarity or homology searches to MHCPEP; 2) BIMAS and 3) artificial neural network-based predictions of proteins MACE, GAGE, EGFR, p185(HER-2/neu) and FR-alpha expressed in INT.Ov lines, Because of the high frequency of expression of some of these proteins in ovarian cancer and the ability to determine HLA binding peptides efficiently, it is expected that after appropriate screening, a large cohort of ovarian cancer patients may become candidates to receive peptide based vaccines. (C) 1997 Wiley-Liss, Inc.

Identification and chromosomal localization of one locus of Leishmania (L.) major related with resistance to itraconazole

Ergosterol is an important compound responsible to maintain integrity and fluidity of Leishmania spp. membranes. Starting from an overexpression/selection method, our group has isolated and mapped nine different loci of Leishmania (L.) major related to resistance against two inhibitors of the ergosterol biosynthesis pathway, terbinafine (TBF) and itraconazole (ITZ). Individual functional analysis after overexpression induction of these loci in the presence of TBF and/or ITZ [or the ITZ analog ketoconazole (CTZ)] have shown low but significant levels of resistance after transfection into L. major wild-type parasites. In this work, we have shown the insert mapping and chromosomal identification of one of these loci (cosItz2). Functional analysis experiments associated with chromosomal localization by comparison at genomic database allowed us to identify two prospective gene-protein systems not related to the ergosterol biosynthesis and capable to confer wild-type cells resistance to ITZ-CTZ after transfection. We expected that this approach can open new insights for a better understanding of mechanisms of ITZ-CTZ action and resistance in Leishmania resulting in new strategies for the leishmaniasis treatment.

Investigating 22q11.2 Deletion and Other Chromosomal Aberrations in Fetuses With Heart Defects Detected by Prenatal Echocardiography

Congenital heart disease (CHD) is the most common birth defect and the leading cause of mortality in the first year of life. In fetuses with a heart defect, chromosomal abnormalities are very frequent. Besides aneuploidy, 22q11.2 deletion is one of the most recognizable chromosomal abnormalities causing CHD. The frequency of this abnormality varies in nonselected populations. This study aimed to investigate the incidence of the 22q11.2 deletion and other chromosomal alterations in a Brazilian sample of fetuses with structural cardiac anomalies detected by fetal echocardiography. In a prospective study, 68 fetuses with a heart defect were evaluated. Prenatal detection of cardiac abnormalities led to identification of aneuploidy or structural chromosomal anomaly in 35.3% of these cases. None of the fetuses with apparently normal karyotypes had a 22q11.2 deletion. The heart defects most frequently associated with chromosomal abnormalities were atrioventricular septal defect (AVSD), ventricular septal defect (VSD), and tetralogy of Fallot. Autosomal trisomies 18 and 21 were the most common chromosomal abnormalities. The study results support the strong association of chromosome alterations and cardiac malformation, especially in AVSD and VSD, for which a chromosome investigation is indicated. In fetuses with an isolated conotruncal cardiopathy, fluorescence in situ hybridization (FISH) to investigate a 22q11.2 deletion is not indicated.

Pompe disease in a Brazilian series: clinical and molecular analyses with identification of nine new mutations

Pompe disease (glycogen storage disease type II or acid maltase deficiency) is an inherited autosomal recessive deficiency of acid alpha-glucosidase (GAA), with predominant manifestations of skeletal muscle weakness. A broad range of studies have been published focusing on Pompe patients from different countries, but none from Brazil. We investigated 41 patients with either infantile-onset (21 cases) or late-onset (20 cases) disease by muscle pathology, enzyme activity and GAA gene mutation screening. Molecular analyses identified 71 mutant alleles from the probands, nine of which are novel (five missense mutations c.136T > G, c.650C > T, c.1456G > C, c.1834C > T, and c.1905C > A, a splice-site mutation c.1195-2A > G, two deletions c.18_25del and c.2185delC, and one nonsense mutation c.643G > T). Interestingly, the c.1905C > A variant was detected in four unrelated patients and may represent a common Brazilian Pompe mutation. The c.2560C > T severe mutation was frequent in our population suggesting a high prevalence in Brazil. Also, eight out of the 21 infantile-onset patients have two truncating mutations predicted to abrogate protein expression. Of the ten late-onset patients who do not carry the common late-onset intronic mutation c.-32-13T > G, five (from three separate families) carry the recently described intronic mutation, c.-32-3C > A, and one sibpair carries the novel missense mutation c.1781G > C in combination with known severe mutation c.1941C > G. The association of these variants (c.1781G > C and c.-32-3C > A) with late-onset disease suggests that they allow for some residual activity in these patients. Our findings help to characterize Pompe disease in Brazil and support the need for additional studies to define the wide clinical and pathological spectrum observed in this disease.

Echocardiographic identification of the oblique vein of the left atrium: its relationship to the persistent left superior caval vein

Thus far, little has been written concerning echocarchographic identification of the oblique of the left atrium, or Marshall`s vein. There is much discussion, nonetheless, on the potential significance of the vein, or its ligamentous remnant, as an arrhythmic substrate. We describe here four patients in whom transthoracic echocardiography revealed a venous structure protruding within the cavity of the left atrium. We discuss the possibility that these structures represent Marshall`s vein, albeit probably as part of a persistent left superior caval vein.

Evaluation of the Frequency of Micronuclei in Exfoliated Cells from Oral Lesions Previously Identified by Toluidine Blue

Objective: Patients using a removable prosthesis are susceptible to a variety of oral lesions that may progress to cancer. Toluidine blue (TB) staining is used to identify premalignant lesions, but the results are still controversial. Since micronuclei (MN) are a biomarker of genetic instability, the objective of this study was to determine the frequency of MN in white lesions of the oral mucosa and to compare the results with those of the TB test. Study Design: The study included 20 removable prosthesis users with white lesions that were previously classified as toluidine positive or negative. The frequency of MN was evaluated in exfoliated cells from lesions and normal mucosa. Nuclear anomalies were also registered. Results: A significant increase (p < 0.05) in the frequency of MN was observed in exfoliated cells from lesions compared to normal mucosal cells, and no relationship was seen with TB staining. Lifestyle factors or gender did not influence the results. Conclusions: The frequency of MN is a sensitive biomarker and can be used to predict genomic instability in white oral lesions. The MN assay may serve as a good parameter in the battery of tests used to identify high-risk individuals, contributing to the identification of the biological conditions of oral lesions. Copyright (C) 2011 S. Karger AG, Basel

Sludge population optimisation: a new dimension for the control of biological wastewater treatment systems

The activated sludge comprises a complex microbiological community. The structure (what types of microorganisms are present) and function (what can the organisms do and at what rates) of this community are determined by external physico -chemical features and by the influent to the sewage treatment plant. The external features we can manipulate but rarely the influent. Conventional control and operational strategies optimise activated sludge processes more as a chemical system than as a biological one. While optimising the process in a short time period, these strategies may deteriorate the long-term performance of the process due to their potentially adverse impact on the microbial properties. Through briefly reviewing the evidence available in the literature that plant design and operation affect both the structure and function of the microbial community in activated sludge, we propose to add sludge population optimisation as a new dimension to the control of biological wastewater treatment systems. We stress that optimising the microbial community structure and property should be an explicit aim for the design and operation of a treatment plant. The major limitations to sludge population optimisation revolve around inadequate microbiological data, specifically community structure, function and kinetic data. However, molecular microbiological methods that strive to provide that data are being developed rapidly. The combination of these methods with the conventional approaches for kinetic study is briefly discussed. The most pressing research questions pertaining to sludge population optimisation are outlined. (C) 2002 Elsevier Science Ltd. All rights reserved.

An advanced method for eliminating impacts from frequency deviations in power system signal processing

Frequency deviation is a common problem for power system signal processing. Many power system measurements are carried out in a fixed sampling rate assuming the system operates in its nominal frequency (50 or 60 Hz). However, the actual frequency may deviate from the normal value from time to time due to various reasons such as disturbances and subsequent system transients. Measurement of signals based on a fixed sampling rate may introduce errors under such situations. In order to achieve high precision signal measurement appropriate algorithms need to be employed to reduce the impact from frequency deviation in the power system data acquisition process. This paper proposes an advanced algorithm to enhance Fourier transform for power system signal processing. The algorithm is able to effectively correct frequency deviation under fixed sampling rate. Accurate measurement of power system signals is essential for the secure and reliable operation of power systems. The algorithm is readily applicable to such occasions where signal processing is affected by frequency deviation. Both mathematical proof and numerical simulation are given in this paper to illustrate robustness and effectiveness of the proposed algorithm. Crown Copyright (C) 2003 Published by Elsevier Science B.V. All rights reserved.

Identification and comparison of aerobic and denitrifying polyphosphate-accumulating organisms

Two laboratory-scale sequencing batch reactors (SBRs) were operated for enhanced biological phosphorus removal (EBPR) in alternating anaerobic-aerobic or alternating anaerobic-anoxic modes, respectively. Polyphosphate-accumulating organisms (PAOs) were enriched in the anaerobic-aerobic SBR and denitrifying PAOs (DPAOs) were enriched in the anaerobic-aerobic SBR. Fluorescence in situ hybridization (FISH) demonstrated that the well-known PAO, Candidatus Accumulibacter phosphatis was abundant in both SBRs, and post-FISH chemical staining with 4,6-diamidino-2-phenylindol (DAPI) confirmed that they accumulated polyphosphate. When the anaerobic-anoxic SBR enriched for DPAOs was converted to anaerobic-aerobic operation, aerobic uptake of phosphorus by the resident microbial community occurred immediately. However, when the anaerobic-aerobic SBR enriched for PAOs was exposed to one cycle with anoxic rather than aerobic conditions, a 5-h lag period elapsed before phosphorus uptake proceeded. This anoxic phosphorus-uptake lag phase was not observed in the subsequent anaerobic-aerobic cycle. These results demonstrate that the PAOs that dominated the anaerobic-aerobic SBR biomass were the same organisms as the DPAOs enriched under anaerobic-anoxic conditions. (C) 2003 Wiley Periodicals, Inc.

Identification of slow and fast-acting toxins in a highly ciguatoxic barracuda (Sphyraena barracuda) by HPLC/MS and radiolabelled ligand binding

A barracuda implicated in ciguatera fish poisoning in Guadeloupe was estimated to have an overall flesh toxicity of 15 MUg/g using mouse bioassay. A lipid soluble extract was separated into two toxic fractions, FrA and FrB, on a LH20 Sephadex column eluted with dichloromethane/methanol (1:1). When intraperitoneal injected into mice, FrA provoked symptoms characteristic of slow-acting ciguatoxins, whereas FrB produced symptoms indicative of fast-acting toxins (FAT). High performance liquid chromatography/mass spectrometry/radio-ligand binding (HPLC/MS/RLB) analysis confirmed the two fractions were distinct, because only a weak overlap of some compounds was observed. HPLC/MS/RLB analysis revealed C-CTX-1 as the potent toxin present in FrA, and two coeluting active compounds at m/z 809.43 and 857.42 in FrB, all displaying the characteristic pattern of ion formation for hydroxy-polyethers. Other C-CTX congeners and putative hydroxy-polyether-like compounds were detected in both fractions, however, the RLB found them inactive. C-CTX-1 accounted for >90% of total toxicity in this barracuda and was confirmed to be a competitive inhibitor of brevetoxin binding to voltage-sensitive sodium channels (VSSCs) with a potency two-times lower than P-CTX-1. However, FAT active on VSSCs and

Identification and characterization of pptA: a gene involved in the phase-variable expression of phosphorylcholine on pili of Neisseria meningitidis

Pili of pathogenic Neisseria are major virulence factors associated with adhesion, cytotoxicity, twitching motility, autoaggregation, and DNA transformation. Pili are modified posttranslationally by the addition of phosphorylcholine. However, no genes involved in either the biosynthesis or the transfer of phosphorylcholine in Neisseria meningitidis have been identified. In this study, we identified five candidate open reading frames (ORFs) potentially involved in the biosynthesis or transfer of phosphorylcholine to pilin in N. meningitidis. Insertional mutants were constructed for each ORF in N. meningitidis strain C311#3 to determine their effect on phosphorylcholine expression. The effect of the mutant ORFs on the modification by phosphorylcholine was analyzed by Western analysis with phosphorylcholine-specific monoclonal antibody TEPC-15. Analysis of the mutants showed that ORF NMB0415, now defined as pptA (pilin phosphorylcholine transferase A), is involved in the addition of phosphorylcholine to pilin in N. meningitidis. Additionally, the phase variation (high frequency on-off switching of expression) of phosphorylcholine on pilin is due to changes in a homopolymeric guanosine tract in pptA.