Obsessive-compulsive disorder: a disorder of pessimal (non-functional) motor behavior

OBJECTIVE

To determine whether in addition to repetitiveness, the motor rituals of patients with obsessive-compulsive disorder (OCD) involve reduced functionality due to numerous and measurable acts that are irrelevant and unnecessary for task completion.

METHOD

Comparing motor rituals of OCD patients with behavior of non-patient control individuals who were instructed to perform the same motor task.

RESULTS

Obsessive-compulsive disorder behavior comprises abundant acts that were not performed by the controls. These acts seem unnecessary or even irrelevant for the task that the patients were performing, and therefore are termed 'non-functional'. Non-functional acts comprise some 60% of OCD motor behavior. Moreover, OCD behavior consists of short chains of functional acts bounded by long chains of non-functional acts.

CONCLUSION

The abundance of irrelevant or unnecessary acts in OCD motor rituals represents reduced functionality in terms of task completion, typifying OCD rituals as pessimal behavior (antonym of optimal behavior).

Adjudication: possible amendment to the 1996 act

This paper addresses proposed changes to the UK Housing Grants, Construction and Regeneration Act 1996, as introduced by part 8 of the Local Democracy, Economic Development and Construction Bill. Strengths of the current act are addressed, together with its weaknesses in light of the courts’ subsequent interpretation of the act. The changes proposed by the bill are evaluated in the context of the current act under the following headings: application of the act; adjudication; payment notice/withholding notice regime; suspension of works. The paper also attempts to identify difficulties in the current act that are not addressed by the proposed reforms and potential new difficulties that the reforms bring.

Automated LC-LC-MS-MS platform using binary ion-exchange and gradient reversed-phase chromatography for improved proteomic analyses

A simple multidimensional liquid chromatography system utilizing an isocratic pump and a HPLC system is described for the comprehensive proteomic analysis of complex peptide digest mixtures by coupled LC-LC-MS-MS techniques. A binary ion-exchange separation was achieved through the use of a strong cation-exchange column followed by a reversed-phase column for data-dependent LC-MS-MS analysis of the unbound analytes, and following salt elution (and concomitant column reequilibration), the bound analytes. Off-line validation of the platform showed near quantitative recovery of fractionated peptides and essentially complete ion-exchange partitioning. In comparative analyses of a highly complex peptide digest mixture a >40% increase in the number of peptide and protein identifications was achieved using this multidimensional platform compared to an unfractionated control.

Towards defining the urinary proteome using liquid chromatography-tandem mass spectrometry. I. Profiling an unfractionated tryptic digest

The proteome of normal male urine from a commercial pooled source has been examined using direct liquid chromatography-tandem mass spectrometry (LC-MS/MS). The entire urinary protein mixture was denatured, reduced and enzymatically digested prior to LC-MS/MS analysis using a hybrid-quadrupole time-of-flight mass spectrometer (Q-TOF) to perform data-dependent ion selection and fragmentation. To fragment as many peptides as possible, the mixture was analyzed four separate times, with the mass spectrometer selecting ions for fragmentation from a subset of the entire mass range for each run. This approach requires only an autosampler on the HPLC for automation (i.e, unattended operation). Across these four analyses, 1.450 peptide MS/MS spectra were matched to 751 sequences to identify 124 gene products (proteins and translations of expressed sequence tags). Interestingly, the experimental time for these analyses was less than that required to run a single two-dimensional gel.

Towards defining the urinary proteome using liquid chromatography-tandem mass spectrometry. II. Limitations of complex mixture analyses

With an emphasis on obtaining a multitude of high quality tandem mass spectrometry spectra for protein identification, instrumental parameters are described for the liquid chromatography-tandem mass spectrometry analysis of trypsin digested unfractionated urine using a hybrid quadrupole-time-of-flight (Q-TOF) mass spectrometer. Precursor acquisition rates of up to 20 distinct precursors/minute in a single analysis were obtained through the use of parallel precursor selection (four precursors/survey period) and variable collision induced dissociation integration time (1 to 6 periods summed). Maximal exploitation of the gas phase fractionated ions was obtained through the use of narrow survey scans and iterative data-dependent analyses incorporating dynamic exclusion. The impact on data fidelity as a product of data-dependent selection of precursor ions from a dynamically excluded field is discussed with regards to sample complexity, precursor selection rates, survey scan range and facile chemical modifications. Operational and post-analysis strategies are presented to restore data confidence and reconcile the greatest number of matched spectra.

Self recognition in the Ig superfamily. Identification of precise subdomains in carcinoembryonic antigen required for intercellular adhesion

The homophilic binding of extracellular domains of membrane-bound immunoglobulin superfamily (IgSF) molecules is often required for intercellular adhesion and signaling. Carcinoembryonic antigen (CEA), a member of the IgSF, is a widely used tumor marker that functions in vitro as a homotypic intercellular adhesion molecule. CEA has also been shown to contribute to tumorigenicity by inhibiting cellular differentiation, an effect that requires the homophilic binding of its extracellular domains. It was of interest, therefore, to identify small subdomain sequences in CEA that could serve as a focus in the design of peptides that disrupt CEA-mediated intercellular adhesion. Three subdomains in the N-terminal domain of CEA, identified by site-directed deletions and point mutations, were shown to be required for intercellular adhesion. Cyclized peptides representing two of these subdomains, (42)NRQII and (80)QNDTG, were found to be effective in blocking CEA-mediated cellular aggregation when added to CEA-expressing transfectants in suspension. Intermolecular binding involving each of these subdomains is therefore essential for intercellular adhesion and cannot be compensated for by known binding contributions of other regions in the CEA molecule. In further support of this assumption, the binding epitope of an anti-CEA monoclonal antibody (monoclonal antibody A20) known to block CEA-mediated adhesion, was shown to bridge two of the three required subdomains: (42)NRQII and (30)GYSWYK.

A simplified device for protein identification by microcapillary gradient liquid chromatography-tandem mass spectrometry

A simplified device and procedure have been developed for microcapillary gradient liquid chromatography-tandem mass spectrometry (LC-MS/MS). This procedure has proved useful in identifying low level quantities of proteins from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel bands. Microelectrospray needles are packed with reversed-phase resin and function both as a high performance liquid chromatography (HPLC) column and a nanospray mass spectrometer tip when interfaced between an HPLC and ion trap mass spectrometer. Variable submicroliter flow rates are generated by flow splitting between the microelectrospray capillary and an HPLC system. A manual injector is used to inject a protein digest mixture that binds to the column and is then washed at a high flow rate (2 microL/min post split). Gradient elution of bound peptides was initiated by the injection of a filled loop of 70% v/v methanol (5 microL) concomitant with a reduction of flow rate (0.1 microL/min post split). This forms a diffusion-dependent gradient of variable length (typically 15-30 min in length) depending upon the final flow rate. Chromatographic separations of a standard solution digest demonstrate that this diffusion-dependent gradient provides reasonable separations such that multiple peptide identifications by MS/MS can be obtained. Application of this methodology to the analysis of several in-gel-digested gel-separated proteins is presented to demonstrate its utility.

DNA bending by EcoRI DNA methyltransferase accelerates base flipping but compromises specificity

EcoRI DNA methyltransferase was previously shown to bend its cognate DNA sequence by 52 degrees and stabilize the target adenine in an extrahelical orientation. We describe the characterization of an EcoRI DNA methyltransferase mutant in which histidine 235 was selectively replaced with asparagine. Steady-state kinetic and thermodynamic parameters for the H235N mutant revealed only minor functional consequences: DNA binding affinity (KDDNA) was reduced 10-fold, and kcat was decreased 30%. However, in direct contrast to the wild type enzyme, DNA bending within the mutant enzyme-DNA complexes was not observed by scanning force microscopy. The bending-deficient mutant showed enhanced discrimination against the methylation at nontarget sequence DNA. This enhancement of enzyme discrimination was accompanied by a change in the rate-limiting catalytic step. No presteady-state burst of product formation was observed, indicating that the chemistry step (or prior event) had become rate-limiting for methylation. Direct observation of the base flipping transition showed that the lack of burst kinetics was entirely due to slower base flipping. The combined data show that DNA bending contributes to the correct assembly of the enzyme-DNA complex to accelerate base flipping and that slowing the rate of this precatalytic isomerization can enhance specificity.

Nature and distribution of radicals in rf and dc silane discharges; effects on deposition rate and physical properties of a-Si:H

Anodic and cathodic processes for rf and dc excited plasmas of silane gas differ in the relative role of charged and neutral radical species. By studying the thickness distribution of films deposited on substrates immersed in the plasma, the relative importance of these species as contributors to the film thickness is assessed. In addition, the impact of the different deposition processes on the spin density in the deposited hydrogenated amorphous silicon films and a key photoelectronic property, the hole range, is discussed.

Conductive Polymers

Recent research has shown that polymers, normally thought of as being insulators, exhibit a wide range of electrical conductive properties.