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PubMed1994

Modulation of complement regulatory function and measles virus receptor function by the serine-threonine-rich domains of membrane cofactor protein (CD46).

Three major membrane cofactor protein (MCP) phenotypes with different serine-threonine (ST)-rich regions, namely STc (L-phenotype), STBC (H or U phenotype) and STABC, and the MCP without the ST domain (delta ST) were expressed in Chinese hamster ovary (CHO) cells by transfecting the respective cDNAs. The expressed molecules migrated with a larger molecular mass on SDS/PAGE than those expected from their amino acid sequences. O-Glycanase digestion showed that this was due to O-linked sugar chains. The apparent sugar contents in each ST segment were compatible with their serine and threonine contents in the ST regions. The functional properties of these phenotypes as inhibitors of human complement (C) and receptors of measles virus (MV) were compared. The classical pathway-dependent CHO cell lysis by human C was more effectively suppressed by the expressed delta ST and STC than by the STABC and STBC phenotypes, although the difference was not so prominent. In contrast, alternative C pathway-dependent CHO-cell lysis was most effectively suppressed by the STABC phenotype and was only slightly blocked by the ST-deleted mutant. MV infection occurred with all of the phenotypes, but the infectious dose required to cause the same level of syncytium formation was 100-times higher in large ST (STABC and STBC) than in small ST (STC and delta ST) phenotypes. Thus, the ST domain serves as a functional modulator in MCP: MCP with a large ST domain having high O-linked sugar contents is favourable to the effective suppression of both the alternative C pathway-mediated cytolysis and MV infection, whereas MCP with a small ST domain is favourable to the suppression of the classical C pathway.

Animals↗

PubMed2005

Insights into biological functions across species: examining the role of Rab proteins in YIP1 family function.

The YIP1 family comprises an evolutionarily conserved group of membrane proteins, which share the ability to bind di-prenylated Rab proteins. The biochemical capability of YIP1 family proteins suggests a possible role in the cycle of physical localization of Rab proteins between their cognate membranes and the cytosol. YIP1 is essential for viability in yeast and a deletion of YIP1 can be rescued with the human homologue YIP1A. We have made use of this evolutionary conservation of function to generate a series of mutant alleles of YIP1 to investigate the biological role of Yip1p. Our findings indicate evidence for the participation of Yip1p in both Rab and COPII protein function; at present, we are not able to distinguish between the models that these roles represent, i.e. independent or dependent activities of Yip1p.

ADP-Ribosylation Factors↗

PubMed2005

RhoGDI-3, a promising system to investigate the regulatory function of rhoGDIs: uncoupling of inhibitory and shuttling functions of rhoGDIs.

rhoGDIs (Rho GDP dissociation inhibitors) are postulated to regulate the activity and the localization of small G-proteins of the Rho family by a shuttling process involving extraction of Rho from donor membranes, formation of inhibitory cytosolic rhoGDI/Rho complexes, and delivery of Rho to target membranes. However, the role of rhoGDIs in site-specific membrane targeting or extraction of Rho is still poorly understood. We investigated here the in vivo functions of two mammalian rhoGDIs: the specific rhoGDI-3 and the well-studied rhoGDI-1 (rhoGDI) after structure-based mutagenesis. We identified two sites in rhoGDIs, forming conserved interactions with their Rho target, whose mutation results in the uncoupling of inhibitory and shuttling functions of rhoGDIs in vivo. Remarkably, these rhoGDI mutants were detected at Rho-induced membrane ruffles or protrusions, where they co-localized with RhoG or Cdc42, probably identifying for the first time the site of extraction of a Rho protein by a rhoGDI in vivo. We propose that these mutations act by modifying the steady-state kinetics of the shuttling process regulated by rhoGDIs, such that transient steps at the cell membranes now become detectable. They should provide valuable tools for future investigations of the dynamics of membrane extraction or delivery of Rho proteins and their regulation by cellular partners.

Guanine Nucleotide Dissociation Inhibitors↗

PubMed1997

Expression of rat CD59: functional analysis confirms lack of species selectivity and reveals that glycosylation is not required for function.

This study reports the expression and functional characterization of the rat analogue of the human complement regulatory molecule CD59. We here describe the expression in chinese hamster ovary (CHO) cells of rat CD59 and a modified rat CD59 in which an N-glycosylation site at Asn-16 has been deleted by point mutation. The complement-inhibiting capacity of these two forms of rat CD59 has been analysed and compared. Expressed rat CD59 efficiently inhibited complement lysis of CHO cells when rat serum was used as a source of complement and also inhibited lysis by complement from all other species tested, confirming that rat CD59 displayed little or no species restriction of activity. Blocking of expressed rat CD59 with a monoclonal antibody abrogated the inhibition of lysis for all sources of complement, confirming that the expressed molecule was responsible for the protection. The glycosylation mutant had a much reduced molecular weight on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) (12,000 MW as compared with 20,000-28,000 MW for unmutated), confirming that it was unglycosylated. However, the glycosylation mutant had complement-inhibitory activity which was at least as potent as that of the unmutated molecule, demonstrating that the large, N-linked carbohydrate moiety was not required for function.

Animals↗

PubMed1999

Seizure disorders in people with intellectual disability: an analysis of differences in social functioning, adaptive functioning and maladaptive behaviours.

The present study is an investigation into the effects of seizure disorders/epilepsy on psychopathology, social functioning, adaptive functioning and maladaptive behaviours using a sample of 353 people diagnosed with a seizure disorder, and either severe or profound intellectual disability. People with a diagnosis of seizure disorder were found to have significantly less social and adaptive skills when compared to developmentally disabled controls with no seizure disorder diagnosis. Additionally, patterns of maladaptive behaviours were identified for individuals with seizure disorders and found to be similar to those found in people without seizure activity. The implications of the present findings are discussed.

Activities of Daily Living↗

PubMed2003

The Prudhoe Cognitive Function Test, a scale to assess cognitive function in adults with Down's syndrome: inter-rater and test-retest reliability.

BACKGROUND: The Prudhoe Cognitive Function Test (PCFT) was designed to measure cognitive function in subjects with all degrees of intellectual disability (ID) and to be administered by non-specialist raters. The aim of the present study was to measure the test-retest and inter-rater reliability of the PCFT. METHODS: Three raters, one a specialist and two non-specialists, administered the PCFT to 14 subjects with Down's syndrome on two occasions separated by 4 weeks. RESULTS: The intra-class correlation coefficients (ICCs) between the rater pairs (n=3) were 0.99, 0.99 and 0.98 (P<0.01). Floor effects were recorded for two items. The ICC for test-retest reliability was 0.99 (P<0.01). CONCLUSIONS: The PCFT is a highly reliable instrument when used by either specialist or non-specialist raters. It has excellent temporal stability.

Adult↗

PubMed2000

A wavefront generator for complex pupil function synthesis and point spread function engineering.

We describe a simple method to produce an arbitrary complex optical field using a ferroelectric liquid crystal spatial light modulator. The system is configured so as to act as a pupil plane filter in a confocal microscope. The ability to tune the complex pupil function permits the system to be used both to modify the imaging performance by effectively engineering the point spread function as well as to remove optical aberrations present in the optical system.

Journal Article↗

PubMed2001

Functional and biological test of a 20 channel implantable stimulator in sheep in view of functional electrical stimulation walking for spinal cord injured persons.

A newly developed implantable stimulator with 20 output channels, mainly intended for the stimulation of lower extremities in paraplegics, was implanted in 6 sheep over a time period of 26 weeks. Five epineural electrodes each were used to contact various nerves at different locations to elicit hip and knee extension and flexion and to make carrousel and selective stimulation possible. Different electrode application strategies in view of paraplegic standing and walking were investigated. Additional implanted electrodes allowed M-wave monitoring for selectivity investigations in 3 sheep. Stimulator, electrode leads, and electrodes proved to be reliable. Selective stimulation with electrodes placed on the trunk of the sciatic nerve could be demonstrated but with bad reproducibility. Histological investigation of the tissues surrounding electrodes and leads showed the expected stable foreign body response. Strong hip and knee extension could be gained in all cases while only weak flexion forces could be elicited in most cases. Muscle biopsies showed that daily stimulation for 8 h at threshold level caused an increase in muscle Type I fibers and a decrease in Type IIc fibers. Implants and electrodes fulfill the most important functional and biological criteria for their clinical application for paraplegic walking. The intention to provide selective flexion functions via epineural stimulation could not be demonstrated sufficiently in this animal model.

Animals↗

PubMed2001

Social functioning, psychological functioning, and quality of life in epilepsy.

PURPOSE: Part of our research intended to explain "Quality of Life" (QoL) differences between people with epilepsy. To this end, a series of already existing generic and disease-specific health status measures were used. In this study, they were considered as determinants of people's QoL, whereas QoL itself was conceived as a general "value judgment" about one's life. METHODS: From the records of four outpatient clinics, 210 persons with epilepsy were randomly selected. During their visit to the outpatient clinic, they completed a questionnaire assessing, among other things, health perceptions and social and psychological functioning. Additional information about their medical and psychosocial status was gathered from the patient files. Data were analysed by using a hierarchical regression analysis. RESULTS: In decreasing order of importance, "psychological distress," "loneliness," "adjustment and coping," and "stigma perception" appeared to contribute most significantly to the outcome QoL as judged by the patients themselves, regardless of their physical status. In the final model, none of the clinical variables (onset, seizure frequency, side effects of antiepileptic drugs) contributed significantly anymore to the patients' "quality-of-life judgement." Apparently the effect of other variables such as seizure frequency and health perceptions, medication and side effects, life fulfillment, self-esteem, and mastery is mediated by these variables. CONCLUSIONS: Because all of the variance in QoL of the patients was explained by the psychosocial variables included in this study, health professionals should be aware of the significance of the psychosocial functioning of the patients and the role it plays in the achievement of a good QoL. Both informal and professional support may be an adjunct to conventional treatment. In future research, this issue should be given high priority.

Adaptation, Psychological↗

PubMed2001

Quantifying swallowing function after stroke: A functional dysphagia scale based on videofluoroscopic studies.

OBJECTIVE: To develop a sensitive, specific scale for quantifying functional dysphagia in stroke patients, using results obtained from videofluoroscopic swallowing studies. DESIGN: Data collected from a serial oral and pharyngeal videofluoroscopic swallowing study. SETTING: A dysphagia clinic in a department of rehabilitation medicine at a tertiary care university hospital. PARTICIPANTS: One hundred three consecutively admitted stroke patients. INTERVENTIONS: Videoflurorscopy to measure a scale of 11 variables: lip closure score, bolus formation, residue in oral cavity, oral transit time, triggering of pharyngeal swallow, laryngeal elevation and epiglottic closure, nasal penetration, residue in valleculae, coating of pharyngeal wall after swallow, and pharyngeal transit time. MAIN OUTCOME MEASURES: Polychotomous linear logistic regression analysis of videofluoroscopic and aspiration results. Scale sensitivity and specificity, and the correlation between the total score of the scale and aspiration grade were analyzed. RESULTS: The scale's sensitivity and specificity for detecting supraglottic penetration and subglottic aspiration were 81%, 70.7%, and 78.1%, 77.9%, respectively. A significant positive correlation was found between the scale's total score and the severity of aspiration (Spearman's r =.58943, p =.00001). CONCLUSION: This functional dysphagia scale, which was based on a videofluoroscopic swallowing study in stroke patients, is a sensitive and specific method for quantifying the severity of dysphagia.

Adult↗

PubMed2000

gamma-glutamyltranspeptidase-deficient knockout mice as a model to study the relationship between glutathione status, mitochondrial function, and cellular function.

gamma-Glutamyltranspeptidase (GGT)-deficient mice (GGT(-/-)) display chronic glutathione (GSH) deficiency, growth retardation, and die at a young age (<20 weeks). Using livers from these mice, we investigated the relationship between GSH content, especially mitochondrial, and mitochondrial and cellular function. We found that the GSH content of isolated liver mitochondria was diminished by >/=50% in GGT(-/-) mice when compared with wild-type mice. Respiratory control ratios (RCRs) of GGT(-/-) mice liver mitochondria were </=60% those of wild-type mice primarily as a result of impaired state 3 respiration. Mitochondrial adenine nucleotide content was decreased by >/=40% in mitochondria obtained from GGT(-/-) mice. We observed a strong correlation between mitochondrial GSH content and RCRs. Even moderate decreases (<50%) correlated with adverse effects with respect to respiration. Electron microscopy revealed that livers from GGT(-/-) knockout mice were deprived of fat and glycogen, and swollen mitochondria were observed in animals that were severely deprived of GSH. Thus, GGT(-/-) mice exhibit a loss of GSH homeostasis and impaired oxidative phosphorylation, which may be related to the rate of adenosine triphosphate (ATP) formation and subsequently leads to progressive liver injury, which characterizes the diseased state. We also found that supplementation of GGT(-/-) mice with N-acetylcysteine (NAC) partially restored liver GSH, but fully restored mitochondrial GSH and respiratory function. Electron microscopy revealed that the livers of NAC-supplemented GGT(-/-) mice contained fat and glycogen; however, slightly enlarged mitochondria were found in some livers. NAC supplementation did not have any beneficial effect on the parameters examined in wild-type mice.

Adenosine Diphosphate↗

PubMed2003

[Esophageal 24 hour-pH metry. Recommendations of the German Society of Neurogastroenterology and Motility and the Study Group for Gastrointestinal Functional Disorders and Function Diagnostics of the Austrian Society of Gastroenterology and Hepatology].

This article presents the recommendations for 24-hour oesophageal pH-metry of the German Society of Neurogastroenterology and Motility and the Study Group for Gastrointestinal Functional Disorders and Function Diagnostics of the Austrian Society of Gastroenterology and Hepatology. Indications for the examination, the procedures to be followed, the analysis of the obtained data and the conclusions to be drawn are delineated. The literature on which the recommendations are based is reviewed.

Adult↗

PubMed1984

[Quantitative functional scintigraphy of the salivary glands. I. Determination of global and regional gland function].

A method for quantifying the function of the salivary glands using the dynamic scintigraphy with 99mTc is presented. After a special back-ground subtraction, the net-time-activity curves of the glands are characterized by 4 quantitative parameters, describing the ability of the glands to accumulate and to excrete the tracer. As a basis for clinical application, normal values are determined and their reproducibility is discussed. To demonstrate also regional functional differences within a single gland, phase-and gradient images are suggested.

Humans↗

PubMed2005

Calculation of optical rotation with time-periodic magnetic-field-dependent basis functions in approximate time-dependent density-functional theory.

We report the implementation of a method for the calculation of optical rotation. This method is based on the time-dependent density-functional theory and utilizes time-periodic magnetic-field-dependent basis functions. The calculations are based on a density fit. It is demonstrated that additional terms in the analytical expression appearing from derivatives of the approximated Coulomb potential are necessary to provide the gauge-origin independence of the results within a given numerical accuracy. Contributions from these terms also restore the symmetry between the electric and magnetic perturbations in the optical rotation tensor.

Algorithms↗

PubMed2005

Condensed-to-atoms electronic Fukui functions within the framework of spin-polarized density-functional theory.

A simple formalism devised to calculate the condensed-to-atoms Fukui function [R. R. Contreras, P. Fuentealba, M. Galván, and P. Pérez, Chem. Phys. Lett. 304, 405 (1999)] has been further analyzed within a spin-polarized density-functional theory framework. The model is based on a frozen-core approximation to these local reactivity indices [M. Galván, A. Vela, and J. L. Gázquez, J. Phys. Chem. 92, 6470 (1988)], giving us an extended local reactivity description of systems based on the frontier spin-up and spin-down molecular orbitals. Degenerate molecular spin orbitals have been explicitly included in our model equations. Computational results for the nitric oxide (NO) and some simple carbene systems are presented in order to test the model. These quantities have been discussed in the context of changes both in charge density and spin density within the context of electron charge transfer or spin-polarization processes.

Journal Article↗

PubMed2005

A new method to reconstruct three-dimensional spatial distribution function from radial distribution function in solvation structure.

Three-dimensional spatial distribution function (SDF) of solvent is a fundamental quantity for analysis of solvation. However, its calculation has been very limited because long computational time is required. We here developed a novel and robust method to construct approximated SDFs of solvent sites from radial distribution functions. In this method, the expansion of SDFs in real solid harmonics around atoms of solute leads to a linear equation, from which SDFs are evaluated with reasonable computational time. This method is applied to the analysis of the solvation structure of liquid water, as an example. The successful results clearly show that this method is very powerful to investigate solvation structure.

Journal Article↗

PubMed2006

New evaluation of reconstructed spatial distribution function from radial distribution functions.

Although three dimensional (3D) solvation structure is much more informative than one dimensional structure, its evaluation is difficult experimentally and theoretically. In our previous Communication [Yokogawa et al., J. Chem. Phys. 123, 211102 (2005)], we proposed a new method to present reconstructed spatial distribution function (RC-SDF) from a set of radial distribution functions (RDFs). In this article, we successfully extended the method more accurately with new basis sets. This new method was applied to two liquid solvation structures, methanol and dimethyl sulfoxide, as examples. Their RC-SDFs evaluated here clearly show that the former solvation structure is well defined while the latter one is broad, which agrees well with the SDFs calculated directly from molecular dynamics simulations. These results indicate that the method can reproduce well these 3D solvation structures in reasonable computational cost.

Journal Article↗

PubMed1998

Functional genomics: probing plant gene function and expression with transposons.

Transposable elements provide a convenient and flexible means to disrupt plant genes, so allowing their function to be assessed. By engineering transposons to carry reporter genes and regulatory signals, the expression of target genes can be monitored and to some extent manipulated. Two strategies for using transposons to assess gene function are outlined here: First, the PCR can be used to identify plants that carry insertions into specific genes from among pools of heavily mutagenized individuals (site-selected transposon mutagenesis). This method requires that high copy transposons be used and that a relatively large number of reactions be performed to identify insertions into genes of interest. Second, a large library of plants, each carrying a unique insertion, can be generated. Each insertion site then can be amplified and sequenced systematically. These two methods have been demonstrated in maize, Arabidopsis, and other plant species, and the relative merits of each are discussed in the context of plant genome research.

Journal Article↗