H high field electron-nuclear double resonance spectroscopy at 263 GHz/9.4 T.

We present and discuss the performance of H electron-nuclear double resonance (ENDOR) at 263 GHz/9.4 T by employing a prototype, commercial quasi optical spectrometer. Basic instrumental features of the setup are described alongside a comprehensive characterization of the new ENDOR probe head design.

Surgical treatment of clival and axis bone cysts.

Objective: The study objective is to present the tactics of surgical treatment of simple (solitary) bone cysts of the clival region and CII body.

Material And Methods: Two patients were operated on for simple clival and axis cysts.

Results: The first patient with a simple clival cyst underwent transoral clivectomy and bone cyst evacuation.

Impact of treatment with intramuscular, injectable, extended-release naltrexone on counseling and support group participation in patients with alcohol dependence.

Objectives: : The impact of intramuscular, injectable, extended-release naltrexone (XR-NTX; Vivitrol) on counseling and support group participation was examined in a post hoc analysis of a 24-week, randomized, double-blind study in 624 alcohol-dependent adults, most of whom were nonabstinent at baseline.

Methods: : Patients were offered 6 monthly injections of XR-NTX 380 mg, XR-NTX 190 mg, or placebo (n = 205, 210, and 209, respectively) and 12 sessions of manualized brief counseling. Voluntary participation in extramural counseling (eg, couples or family therapy) and self-help support groups (eg, Alcoholics Anonymous) was permitted and assessed.

Sleep and substance use and abuse in adolescents.

Substance use disorders and sleep disorders are among the most common psychiatric problems in children and adolescents. They often co-occur and have a significant negative effect upon normal development. This article provides a review of the most recent literature on the relationship between these disorders, along with recommendations on how to recognize and clinically address these disorders in children and adolescents.

Probing the role of the proximal heme ligand in cytochrome P450cam by recombinant incorporation of selenocysteine.

The unique monooxygenase activity of cytochrome P450cam has been attributed to coordination of a cysteine thiolate to the heme cofactor. To investigate this interaction, we replaced cysteine with the more electron-donating selenocysteine. Good yields of the selenoenzyme were obtained by bacterial expression of an engineered gene containing the requisite UGA codon for selenocysteine and a simplified yet functional selenocysteine insertion sequence (SECIS).

A multi-frequency pulse EPR and ENDOR approach to study strongly coupled nuclei in frozen solutions of high-spin ferric heme proteins.

In spite of the tremendous progress in the field of pulse electron paramagnetic resonance (EPR) in recent years, these techniques have been scarcely used to investigate high-spin (HS) ferric heme proteins. Several technical and spin-system-specific reasons can be identified for this. Additional problems arise when no single crystals of the heme protein are available.

Thermally induced spin transitions in nitroxide-copper(II)-nitroxide spin triads studied by EPR.

Thermally induced spin transitions in a family of heterospin polymer chain complexes of Cu2+ hexafluoroacetylacetonate with two pyrazole-substituted nitronyl nitroxides are studied using electron paramagnetic resonance (EPR) spectroscopy. The structural rearrangements at low temperatures induce spin transitions in exchange-coupled spin triads of nitroxide-copper(II)-nitroxide. The values of exchange interactions in spin triads of studied systems are typically on the order of tens to hundreds of inverse centimeters.

Open-label study of a proprietary treatment program targeting type A gamma-aminobutyric acid receptor dysregulation in methamphetamine dependence.

Objective: To evaluate the safety and efficacy of the pharmacological component of a proprietary medical treatment program targeting type A gamma-aminobutyric acid receptor dysregulation in adults who met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria for methamphetamine dependence.

Participants And Methods: A prospective, open-label, single-group study of the medication portion of a proprietary treatment program for methamphetamine dependence was conducted from July 1, 2005, to May 10, 2006, at Research Across America, an outpatient private, for-profit, clinical research company in Dallas, TX. In the study, flumazenil, hydroxyzine, and gabapentin, all of which were approved by the US Food and Drug Administration for indications other than drug dependence, were used off-label for the treatment of methamphetamine dependence.

Electron spin exchange processes in strongly coupled spin triads.

The complexes of Cu2+ hexafluoroacetylacetonate with two pyrazol-substituted nitronyl nitroxides are the choice systems to study the spin dynamics of strongly exchange-coupled spin triads. The large values of exchange coupling (ca. 100 cm-1) and high-resolution electron paramagnetic resonance (EPR) at Q- and W-bands (35 and 94 GHz) allowed us to observe and interpret specific characteristics of these systems.

Axial coordination of heme in ferric CcmE chaperone characterized by EPR spectroscopy.

In Escherichia coli cytochrome c maturation requires a set of eight proteins including the heme chaperone CcmE, which binds heme transiently, yet covalently. Several variants of CcmE were purified and analyzed by continuous-wave electron paramagnetic resonance, electron nuclear double resonance, and hyperfine sublevel correlation spectroscopy to investigate the heme axial coordination. Results reveal the presence of a number of coordination environments, two high-spin heme centers with different rhombicities, and at least one low-spin heme center.

Sensitivity optimization in amplitude-modulated CW-EPR experiment.

A sensitivity of recently developed method of amplitude-modulated continuous wave EPR (AM-CW-EPR) is studied depending on the parameters of the modulation field. The case of the significant saturation and high modulation frequency is addressed. It is found, that the rapid resonance passage effect is essential for AM-CW-EPR.

Electron paramagnetic resonance of three-spin nitroxide-copper(II)-nitroxide clusters coupled by a strong exchange interaction.

The complex of Cu(2+) hexafluoroacetylacetonate with two pyrazol-substituted nitronyl nitroxides represents an unusual exchange-coupled three-spin system. The antiferromagnetic exchange coupling, which already atT < 150 K is larger than the thermal energy kT, induces the transition from a total spin state S = (3)/(2) to a state S = (1)/(2) and produces static spin polarization. Anomalous electron paramagnetic resonance (EPR) spectra of an S = (1)/(2) state were detected experimentally and described theoretically.

Absorption line CW EPR using an amplitude modulated longitudinal field.

In standard continuous wave electron paramagnetic resonance (CW-EPR) experiments, the first derivative of absorption lines is detected. This type of a line shape is caused by the magnetic field modulation and is usually an undesired feature, since the sensitivity of CW-EPR drastically decreases with increasing linewidth. A new approach is introduced, which allows for the measurement of absorption line EPR spectra in systems with broad inhomogeneous lines.

Applications of pi-photon-induced transparency in two-frequency pulse electron paramagnetic resonance experiments.

An approach to pulse electron paramagnetic resonance (EPR) experiments which are based on two different resonance fields is introduced. Instead of using two microwave (mw) sources or a magnetic field jump, bichromatic pulses consisting of a transverse microwave field with frequency omega(mw) and a longitudinal radio frequency field with frequency omega(rf) are employed. Such bichromatic pulses excite a number of multiple photon transitions at frequencies omega(mw)+komega(rf) (k in Z).

The continuous wave electron paramagnetic resonance experiment revisited.

When the modulation frequency used in continuous wave electron paramagnetic resonance (cw EPR) spectroscopy exceeds the linewidth, modulation sidebands appear in the spectrum. It is shown theoretically and experimentally that these sidebands are actually multiple photon transitions, sigma(+)+kxpi, where one microwave (mw) sigma(+) photon is absorbed from the mw radiation field and an arbitrary number k of radio frequency (rf) pi photons are absorbed from or emitted to the modulation rf field. Furthermore, it is demonstrated that both the derivative shape of the lines in standard cw EPR spectra and the distortions due to overmodulation are caused by the unresolved sideband pattern of these lines.

Pulsed EPR/ENDOR characterization of perturbations of the Cu(A) center ground state by axial methionine ligand mutations.

The effect of axial ligand mutation on the Cu(A) site in the recombinant water soluble fragment of subunit II of Thermus thermophilus cytochrome c oxidase ba(3) has been investigated. The weak methionine ligand was replaced by glutamate and glutamine which are stronger ligands. Two constructs, M160T0 and M160T9, that differ in the length of the peptide were prepared.

A Q-band pulse EPR/ENDOR spectrometer and the implementation of advanced one- and two-dimensional pulse EPR methodology.

A versatile high-power pulse Q-band EPR spectrometer operating at 34.5--35.5 GHz and in a temperature range of 4--300 K is described.

Multiphoton resonances in pulse EPR.

Two- and three-photon electron spin echoes of a two-level system are observed using, in addition to the microwave excitation, a linearly polarized radio-frequency field oriented along the static magnetic field B(0). Such multiphoton echoes are detected when the sum of the energies of one microwave and one or two radio-frequency photons are equal to the difference between energies of two spin states. The multiphoton character of the echoes is confirmed by measuring the spin nutation frequency as a function of the angle between the radio-frequency field and B(0), and monitoring the echo amplitude as a function of the radiation field strengths.

[Autoantibodies against NMDA-receptors in the blood of patients with acute disorders of cerebral circulation].

Concentration of autoantibodies to human brain NMDA-receptor in blood serum of patients with acute brain ischemic stroke was significantly higher than in healthy persons and patients with other neurological diseases. Average content of cholesterol, lipid peroxides and glutamate in the serum were close in all patient groups investigated. It was suggested that the content of autoantibodies to human brain NMDA-receptor could be used as biochemical criteria for acute brain stroke patient's condition control and their treatment efficiency.

Azide binding to the trinuclear copper center in laccase and ascorbate oxidase.

Azide binding to the blue copper oxidases laccase and ascorbate oxidase (AO) was investigated by electron paramagnetic resonance (EPR) and pulsed electron-nuclear double resonance (ENDOR) spectroscopies. As the laccase : azide molar ratio decreases from 1:1 to 1:7, the intensity of the type 2 (T2) Cu(II) EPR signal decreases and a signal at g approximately 1.9 appears.

A W-band pulsed ENDOR spectrometer: setup and application to transition metal centers.

The design and performance of a 95 GHz pulsed W-band EPR/ENDOR spectrometer is described with emphasis on the ENDOR part. Its unique feature is the easy and fast sample exchange at 4.2 K for frozen solution and single crystal samples.