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PubMed2006

Visuospatial executive function in Turner syndrome: functional MRI and neurocognitive findings.

Turner syndrome is a genetic disorder that results from an abnormal or missing X chromosome in females and is typically associated with impairments in visuospatial, but not verbal, information processing. These visuospatial processing impairments may be exacerbated with increased task demands, such as those engaged during working memory (WM). While previous studies have examined spatial WM function in Turner syndrome, none have directly compared the neural correlates of spatial and verbal WM processes across the encoding, maintenance and retrieval phases. We employed both neurocognitive assessments and functional MRI (fMRI) to examine the neural circuitry underlying both verbal and visuospatial WM functions in individuals with Turner syndrome and normal controls. We furthermore examined the vulnerability of task-related fMRI activation to distracters presented during WM maintenance. Fifteen healthy female volunteers and eight individuals with Turner syndrome performed a delayed-response WM task during fMRI scanning. Neurocognitive tests revealed impaired performance across both verbal and spatial domains in Turner syndrome, with greater impairment on tasks with WM demands. Frontoparietal regions in controls showed significantly sustained levels of activation during visuospatial WM. This sustained activation was significantly reduced in the group with Turner syndrome. Domain-specific activation of temporal regions, in contrast, did not differ between the two groups. Sensory distraction during the WM maintenance phase did not differentially alter frontoparietal activation between the two groups. The results reveal impaired frontoparietal circuitry recruitment during visuospatial executive processing in Turner syndrome, suggesting a significant role for the X chromosome in the development of these pathways.

Adolescent↗

PubMed2006

Radiation clastogenesis and cell cycle checkpoint function as functional markers of breast cancer risk.

BACKGROUND: Familial breast cancer is associated with mutations in several genes (BRCA1, BRCA2, p53, ATM) whose protein products protect against radiation-induced genotoxicity. This study tested whether sporadic breast cancer was associated with constitutive radiation hypersensitivity. METHODS: Blood lymphocytes and EBV-transformed lymphoblasts from patients with newly diagnosed breast cancer and controls without cancer were evaluated for ionizing radiation (IR)-induced chromosomal aberrations and cell cycle delays. Lymphoblasts from patients with ataxia telangiectasia (AT) and heterozygous AT carriers were tested as positive controls for radiation hypersensitivity. RESULTS: Lymphoblasts from AT patients and AT carriers displayed G2-irradiation, chromosomal hypersensitivity (GICH). Irradiated G2 phase lymphocytes from breast cancer cases and controls displayed 3-fold inter-individual variation in frequencies of chromatid damage. However, the percentage of breast cancer cases with damage frequencies in excess of 2 SD of the control mean (8/102 or 8%) was not significantly elevated compared to controls (2/48 or 4%, P=0.5). Lymphoblasts sampled 24 h after 3 Gy of IR also varied in the ratios of cells with 4N and 2N DNA content (4N/2N ratio), as a measure of cell cycle checkpoint function. 4N/2N ratios in irradiated lymphoblasts were strongly correlated with the fractions of S phase cells in un-irradiated control cultures (Pearson's correlation coefficient, r=0.87). After normalization to S fraction, the radiation-induced increment in the 4N/2N ratio was significantly elevated in AT lymphoblasts but not in lymphoblasts from AT carriers. The fraction of breast cancer cases with reduced checkpoint function (2/45 or 4%) was equal to the control fraction (2/45 or 4%). For breast cancer cases and controls, GICH in primary lymphocytes was not associated with reduced cell cycle checkpoint function in lymphoblasts. CONCLUSION: Constitutive radiation hypersensitivity in blood lymphocytes and lymphoblasts was not a useful biomarker for identifying women at increased risk of breast cancer.

Ataxia Telangiectasia Mutated Proteins↗

PubMed2003

Gain-of-function mutations indicate that Escherichia coli Kch forms a functional K+ conduit in vivo.

Although Kch of Escherichia coli is thought to be a K(+) channel by sequence homology, there is little evidence that it actually conducts K(+) ions in vitro or in vivo. We isolated gain-of-function (GOF) Kch mutations that render bacteria specifically sensitive to K(+) ions. Millimolar added K(+), but not Na(+) or sorbitol, blocks the initiation or continuation of mutant growth in liquid media. The mutations are mapped at the RCK (or KTN) domain, which is considered to be the cytoplasmic sensor controlling the gate. Additional mutations directed to the K(+)-filter sequence rescue the GOF mutant. The apparent K(+)-specific conduction through the 'loose-cannon' mutant channel suggests that the wild-type Kch channel also conducts, albeit in a regulated manner. Changing the internal ATG does not erase the GOF toxicity, but removes kch's short second product, suggesting that it is not required for channel function in vivo. The mutant phenotypes are better explained by a perturbation of membrane potential instead of internal K(+) concentration. Possible implications on the normal function of Kch are discussed.

Amino Acid Sequence↗

PubMed1992

Transfection of HLA-DR-expressing DAP.3 cells with a cDNA clone encoding the glycosyl phosphatidylinositol-linked form of lymphocyte function associated antigen-3: biochemical features and functional consequences.

Structural and functional aspects of the accessory molecule lymphocyte function associated antigen (LFA)-3 (CD58) have been examined following the transfection of DAP.3 and P815 cells with a cDNA clone encoding the glycosyl phosphatidylinositol (GPI)-linked form of human LFA-3. Despite earlier observations that DAP.3 cells are deficient in GPI anchoring LFA-3 was expressed efficiently on DAP.3, as well as on P815 cells. Immunoprecipitation of LFA-3 from 35S-labelled cells revealed that the molecule expressed on the DAP.3 cells had a molecular weight intermediate between the transmembrane and GPI-linked forms expressed by human B cells. This suggests that the DAP.3 cells have a default pathway whereby the RNA transcript which encodes the GPI-linked form of the molecule can also encode an integral membrane protein. Functionally, expression of LFA-3 by DAP.3 which had previously been transfected with the genes encoding HLA-DR1 led to a marked augmentation of the proliferative response of five out of eight anti-DR1 human T cell clones. This effect was not reproduced when DR1 and LFA-3 were expressed by separate populations of DAP.3 cells, suggesting that the ligands for CD2 and for the T cell's receptor must be expressed on the same cell membrane. Expression of human LFA-3 also led to a substantial increase in the proliferative response of human peripheral blood T cells to a DR alloantigen. Separation of T cells into CD45RO+ and CD45RO- populations revealed that the augmentation was more marked for the memory than the virgin population. The mechanisms responsible for these differences are discussed.

Animals↗

PubMed2003

Selenoprotein metabolism and function: evidence for more than one function for selenoprotein P.

Biological functions of selenium are exerted by selenoproteins that contain selenocysteine in their primary structure. Selenocysteine is synthesized and inserted into proteins cotranslationally by a complex process. Families of selenoproteins include the glutathione peroxidases, the iodothyronine deiodinases and the thioredoxin reductases. These are redox enzymes that take advantage of the chemical properties of selenium to catalyze, respectively, removal of hydroperoxides by glutathione, deiodination of thyroid hormones and support of cellular processes requiring reduction of disulfides. Approximately 10 additional selenoproteins have been identified. One of them, selenoprotein P, is an extracellular protein that contains most of the selenium in plasma. It associates with endothelial cells, probably through its heparin-binding properties. Selenoprotein P has been postulated to protect against oxidative injury and to transport selenium from the liver to peripheral tissues. Selenium-dependent protection against diquat-induced liver necrosis and lipid peroxidation in the rat correlates with the presence of selenoprotein P. Recent results support a transport function. When (75)SeO(3)(2-) was administered intravenously to rats, liver tissue took up (75)Se within minutes, associated with a rapid decline in plasma (75)Se. Brain tissue did not begin accumulating (75)Se until (75)Se-labeled selenoprotein P had begun appearing in the plasma after 30 min. These results suggest that tissues like liver can take up small-molecule forms of selenium whereas presence of the element in selenoprotein P facilitates uptake by tissues like brain. Thus, there is evidence for both antioxidant and selenium transport functions of selenoprotein P.

Animals↗

PubMed1988

Conservation of short patches of amino acid sequence amongst proteins with a common function but evolutionarily distinct origins: implications for cloning genes and for structure-function analysis.

Small patches of identical amino acid sequences commonly occur in proteins that have the same function but are derived from evolutionarily distant organisms. Reverse translation of such patches into degenerate pools of oligonucleotides provide useful hybridization probes for cloning the gene for the corresponding protein from other organisms. Since the conserved patches of identical amino acid sequence are probably important for the protein's biological function, they are preferred targets for reverse genetic studies aimed at defining structure-function relationships.

Amino Acid Sequence↗

PubMed2001

Identification of partial loss of function p53 gene mutations utilizing a yeast-based functional assay.

Missense mutations within the central DNA binding region of p53 are the most prevalent mutations found in human cancer. Numerous studies indicate that 'hot-spot' p53 mutants (which comprise approximately 30% of human p53 gene mutations) are largely devoid of transcriptional activity. However, a growing body of evidence indicates that some non-hot-spot p53 mutants retain some degree of transcriptional activity in vivo, particularly against strong p53 binding sites. We have modified a previously described yeast-based p53 functional assay to readily identify such partial loss of function p53 mutants. We demonstrate the utility of this modified p53 functional assay using a diverse panel of p53 mutants.

Base Sequence↗

PubMed2003

OntoBlast function: From sequence similarities directly to potential functional annotations by ontology terms.

OntoBlast allows one to find information about potential functions of proteins by presenting a weighted list of ontology entries associated with similar sequences from completely sequenced genomes identified in a BLAST search. It combines, in a single analysis step, the search for sequence similarities in several species with the association of information stored in ontologies. From each identified ontology term a list of genes, which share the functional annotation, can be retrieved. The OntoBlast function is an integral part of the 'Ontologies TO GenomeMatrix' tool which provides an alternative entry point from ontology terms to the Genome-Matrix database. OntoBlast's web interface is accessible on the 'Ontologies TO GenomeMatrix Gate' page at http://functionalgenomics.de/ontogate/.

Animals↗

PubMed2006

The Mouse Functional Genome Database (MfunGD): functional annotation of proteins in the light of their cellular context.

MfunGD (http://mips.gsf.de/genre/proj/mfungd/) provides a resource for annotated mouse proteins and their occurrence in protein networks. Manual annotation concentrates on proteins which are found to interact physically with other proteins. Accordingly, manually curated information from a protein-protein interaction database (MPPI) and a database of mammalian protein complexes is interconnected with MfunGD. Protein function annotation is performed using the Functional Catalogue (FunCat) annotation scheme which is widely used for the analysis of protein networks. The dataset is also supplemented with information about the literature that was used in the annotation process as well as links to the SIMAP Fasta database, the Pedant protein analysis system and cross-references to external resources. Proteins that so far were not manually inspected are annotated automatically by a graphical probabilistic model and/or superparamagnetic clustering. The database is continuously expanding to include the rapidly growing amount of functional information about gene products from mouse. MfunGD is implemented in GenRE, a J2EE-based component-oriented multi-tier architecture following the separation of concern principle.

Animals↗

PubMed2006

Phytophthora functional genomics database (PFGD): functional genomics of phytophthora-plant interactions.

The Phytophthora Functional Genomics Database (PFGD; http://www.pfgd.org), developed by the National Center for Genome Resources in collaboration with The Ohio State University-Ohio Agricultural Research and Development Center (OSU-OARDC), is a publicly accessible information resource for Phytophthora-plant interaction research. PFGD contains transcript, genomic, gene expression and functional assay data for Phytophthora infestans, which causes late blight of potato, and Phytophthora sojae, which affects soybeans. Automated analyses are performed on all sequence data, including consensus sequences derived from clustered and assembled expressed sequence tags. The PFGD search filter interface allows intuitive navigation of transcript and genomic data organized by library and derived queries using modifiers, annotation keywords or sequence names. BLAST services are provided for libraries built from the transcript and genomic sequences. Transcript data visualization tools include Quality Screening, Multiple Sequence Alignment and Features and Annotations viewers. A genomic browser that supports comparative analysis via novel dynamic functional annotation comparisons is also provided. PFGD is integrated with the Solanaceae Genomics Database (SolGD; http://www.solgd.org) to help provide insight into the mechanisms of infection and resistance, specifically as they relate to the genus Phytophthora pathogens and their plant hosts.

Algal Proteins↗

PubMed1995

Functional consequences of substitution of the disulfide-bonded segment, Cys127-Cys150, located in the extracellular domain of the Na,K-ATPase beta subunit: Arg148 is essential for the functional expression of Na,K-ATPase.

The Cys127-Cys150 disulfide-bonded loop (L1) of the Torpedo californica Na,K-ATPase beta 1 subunit was substituted with the corresponding loop of the rat beta 1, mouse beta 2, or pig H,K-ATPase beta subunit. All the substituted mutant beta subunits assembled with the Na,K-ATPase alpha subunit in a trypsin-resistant manner. The mutants with L1 from the Na,K-ATPase beta subunit isoforms (rat beta 1 and mouse beta 2) each formed a functional complex with the Na,K-ATPase alpha subunit. On the other hand, the complex of the alpha subunit with the mutant beta subunit that was substituted with the pig H,K-ATPase beta subunit L1 was inactive as to ATP hydrolysis. Ser131 and Phe148 located within L1 of the pig H,K-ATPase beta subunit-substituted mutant were back-mutated to Pro131 and Arg148, respectively. The Phe148 to Arg mutation restored the ability of the mutant beta subunit substituted with the H,K-ATPase beta subunit L1 to form a functional complex with the alpha subunit. These results suggested that the Cys127-Cys150 loop of the Na,K-ATPase beta 1 subunit, especially Arg148, plays a critical role in the functional expression of Na,K-ATPase.

Amino Acid Sequence↗

PubMed2003

The multidimensional scale of independent functioning: a new instrument for measuring functional disability in psychiatric populations.

The Multidimensional Scale of Independent Functioning (MSIF) is a new instrument for rating functional disability in psychiatric outpatients. The MSIF differs from other disability rating scales by providing discrete ratings of (1) role responsibility, (2) presence and level of support, and (3) performance quality. The MSIF, which consists of a semistructured interview and detailed rating anchors, was validated in 114 psychiatric outpatients. The instrument had good criterion, discriminative, interrater, and construct validity. Correlations between comparable ratings on the Social Adjustment Scale II (SAS II) ranged from 0.78 to 0.86. Nevertheless, redundancy analysis using canonical correlation demonstrated that, although the two instruments overlap, the MSIF contains information that is not contained in the SAS II. Furthermore, there was only modest shared variance with conceptually non-overlapping subscales in the SAS II. Interrater reliability (intraclass correlation coefficients) ranged from 0.74 to 1.00 for global and subscale scores. MSIF subscales performed as expected with respect to external validators such as hours of employment, earned income, supported versus nonsupported employment and housing, and mainstream versus nonmainstream educational status. MSIF global ratings were modestly correlated with IQ and psychopathology ratings, consistent with reports in the literature. Construct validity, estimated using Cronbach's alpha coefficient, was 0.72. The MSIF is a promising new instrument designed to circumvent several limitations with existing functional outcome instruments for longitudinal studies, intervention research, and services research.

Demography↗

PubMed1991

Structure-function relationships of the C-terminal functional domain of hirudin and its variants.

The C-terminal functional domain of hirudin, hirudin variant 1 (residues 55-65), binds to a non-catalytic site on thrombin. In doing so, it is capable of inhibiting the procoagulant actions of thrombin. In terms of free energy of binding, this domain, which comprises 17% of the total sequence of the protein, contributes approximately half of the binding energy of the whole protein to thrombin. This situation also appears to hold true for the known variants of hirudin, some of which differ in the functional nature of their C-terminal regions. Extensive structure-function studies on this domain yield insights into the differences and similarities in the modes of thrombin interaction of hirudin and its variants. In particular, hirudin and hirudin PA have a similar and somewhat interchangeable structure-activity relationships (SAR) profile that indicates that they interact with thrombin in a similar manner. Hirullin P18, a 62 amino acid member of the hirudin family and isolated from Hirudinaria manillensis, is substantially different in sequence and its SAR, which shows that, although it seems to utilize the same non-catalytic binding domain as hirudin, it must utilize a different mode of interaction with thrombin.

Amino Acid Sequence↗

PubMed1999

Functional MRI of human Pavlovian fear conditioning: patterns of activation as a function of learning.

fMRI was used to study human brain activity during Pavlovian fear conditioning. Subjects were exposed to lights that either signaled painful electrical stimulation (CS+), or that did not serve as a warning signal (CS-). Unique patterns of activation developed within anterior cingulate and visual cortices as learning progressed. Training with the CS+ increased active tissue volume and shifted the timing of peak fMRI signal toward CS onset within the anterior cingulate. Within the visual cortex, active tissue volume increased with repeated CS+ presentations, while cross-correlation between the functional time course and CS- presentations decreased. This study demonstrates plasticity of anterior cingulate and visual cortices as a function of learning, and implicates these regions as components of a functional circuit activated in human fear conditioning.

Adult↗

PubMedDate not supplied

Surgical correction of "functional retroversion" and "functional coxa vara" in late Legg-Calvé-Perthes disease and epiphyseal dysplasia: correction of deformity defined by new imaging modalities.

We studied six patients with severe femoral head deformity treated surgically by valgus-flexion-internal-rotation femoral osteotomy plus simultaneous acetabuloplasty based on the concept of "functional retroversion" and "functional coxa vara" of the deformed femoral head in late severe Legg-Calvé-Perthes disease and epiphyseal dysplasia. The combined procedure achieves the following: (i) corrects the "functional coxa vara" and hinge abduction (valgus osteotomy); (ii) establishes a more normal articulation between the posteromedial portion of the true femoral head and the acetabulum, while moving the anterolateral protruding portion of the femoral head away from the anterolateral acetabular margin (valgus-flexion osteotomy); (iii) corrects external-rotation deformity of the distal limb (internal-rotation osteotomy); (iv) improves joint congruity and anterolateral femoral-head coverage in hips with associated acetabular dysplasia (acetabuloplasty).

Adolescent↗

PubMedDate not supplied

Symptoms, gastric function, and psychosocial factors in functional dyspepsia.

INTRODUCTION: The classification of functional dyspepsia into meaningful subgroups remains an important goal. The aim of this investigation was to determine correlations between dyspeptic symptoms with gastric physiology and psychologic distress. METHODS: Consecutive patients with functional dyspepsia were evaluated with electrogastrography (EGG), drink test, and solid phase gastric emptying. Subjects also completed the Nepean Dyspepsia Index, Psychologic General Well-Being Index, SCL-90R, and SF-36. RESULTS: Eighty-one patients were evaluated. Gastric emptying was performed in 29 of 81 patients and was abnormal in 21%, but no correlation existed between symptoms and T1/2 or TLAG. EGG was abnormal in 42% and drink test was abnormal in 40% of patients. Both were significantly associated with nausea but not with other symptoms. Significant correlations existed with 10 of 15 assessed symptoms and various subscales of the SCL-90R. Somatization was associated with abdominal burning, chest pain, abdominal pressure, abdominal discomfort, bad breath, chest burning, excessive fullness, bloating, abdominal pain, and regurgitation. Anxiety was associated with abdominal burning, chest pain, abdominal pressure, and abdominal discomfort. Anger-hostility was associated with abdominal burning and abdominal pressure. Increased interpersonal sensitivity was associated with abdominal burning and chest burning. SCL-90R Global Symptom Score was associated with abdominal burning, chest pain, abdominal discomfort, and bad breath. CONCLUSIONS: Abnormal gastric physiology as measured in this study was not associated with symptoms other than nausea. Significant associations existed between measures of psychiatric distress and digestive symptoms. Symptoms in functional dyspepsia had greater associations with psychologic distress than with commonly employed tests of gastric physiology.

Adult↗

PubMed1988

The engymetric determination of acute functional impairment in kidney graft function caused by cyclosporine A.

Engymetry offers a new means of continuously measuring nuclear radiation fields without any need of restricting the patient's mobility. In this study, kidney function was measured simultaneously and continuously for 6.6 h with engymetry, after application of a 12 h therapy dose of Cyclosporine A (CsA) of 4.0 +/- 1.8 mg per kg bodyweight (bw). 15 kidney transplanted patients participated in this study. 370 MBq 99Tcm-DTPA and 10 MBq 131I-OIH were injected during routine transplant scintigraphy. Renal function was monitored from the external disappearance curves of the tracers recorded by portable double radionuclide detectors. Renal impairment could be seen in the rising phase of CsA or coincided with the CsA maximum in 13 of the 15 patients. Under the impairment the half-life of 99Tcm-DTPA increased from 4.1 +/- 1.2 to 15.9 +/- 12.3 h (p less than 0.005) for 61 +/- 45 min and the half-life of 131I-OIH increased from 3.2 +/- 0.7 to 12.7 +/- 8.4 h (p less than 0.001) for 71 +/- 37 min. With noninvasive engymetry it is possible to detect renal functional impairment during long observation periods. Acute restriction in glomerular filtration and renal blood flow was discovered in human kidney graft recipients after the application of a low therapeutic CsA dose.

Acute Kidney Injury↗

PubMed2001

Functional classification of patients with idiopathic scoliosis assessed by the Quantec system: a discriminant functional analysis to determine patient curve magnitude.

STUDY DESIGN: A stepwise discriminant analysis was used to define a spinal deformity score based on three-dimensional measurements by the Quantec spinal image system (raster stereophotograph). OBJECTIVE: To provide functional classification of spinal deformity in patients with mild idiopathic scoliosis without using radiographs. SUMMARY OF BACKGROUND DATA: Most studies classify the degree of spinal deformity in terms of coronal plane radiograph without analyzing transverse rotation. To the authors' knowledge, no studies investigating classification of spinal deformity in idiopathic scoliosis using Quantec system measurements have been documented. METHODS: In this study, 129 patients with a single curve and 119 patients with a double curve were divided into three groups according to Cobb angle: Group 1 (less than 10 degrees ), Group 2 (10-20 degrees ), and Group 3 (greater than 20 degrees ). RESULTS: The patients were assigned to the group with the highest scores after application of a stepwise discriminant analysis. The accuracy of the classification system by functional scores for the patients with a single curve was 85% for Group 1, 63.5% for Group 2, and 71.7% for Group 3. The accuracy of classification by functional scores for the patients with a double curve was 87.1% for Group 2 and 76.1% for Group 3. CONCLUSION: The back surface image study is a method for providing a quantitative assessment of mild spinal deformity, allowing evaluation of patients by integrated three-dimensional parameters with no reference to radiographs.

Adolescent↗