Repetitive TMS

Repetitive TMS, unlike electroconvulsive therapy (ECT), uses sub-convulsive stimuli to treat depression. Compared to ECT, TMS has a potential to target specific brain regions and to stimulate brain areas thought to be primarily involved in depression while sparing areas like the hippocampus, thereby reducing the probability of cognitive side effects. However, the therapeutic efficacy of TMS as a treatment for depression is, unlike ECT, modest. Most TMS studies use high-frequency, fast stimulation (> 10 Hz) over the left dorsolateral prefrontal cortex, an area which has been... 

Figure 37.2 demonstrates the electric field pulse produced by a figure-of-eight coil, as measured by a two-wire probe in a brain phantom filled with saline solution at physiologic concentration. In repetitive TMS (rTMS), several such pulses are administered in a train of between 1 and 20 Hz. 

If cross peaks are of unequal volumes, aij Tm) a,ji Tm), owing to short repetition time or spectral distortions, it is best to normalize the geometric mean of the cross peaks by the geometric mean of their respective diagonals. Although approximate, eq. (30) is useful because errors of peak volumes often exceed errors introduced by the truncated Taylor expansion. The limitations and criteria for the validity of Taylor expansion are described elsewhere [55]. 

Fig. 4. Two-dimensional (2D) spectra of cyclo(Pro-Gly), 10 mM in 70/30 volume/volume DMSO/H2O mixture at CLio/27r = 500 MHz and T = 263 K. (A) TCX SY, t = 55 ms. (B) NOESY, Tm = 300 ms. (C) ROESY, = 300 ms, B, = 5 kHz. (D) T-ROESY, Tin = 300 ms, Bi = 10 kHz. Contours are plotted in the exponential mode with the increment of 1.41. Thus, a peak doubles its intensity every two contours. All spectra are recorded with 1024 data points, 8 scans per ti increment, 512 fi increments repetition time was 1.3 s and 90 = 8 ps 512x512 time domain data set was zero filled up to 1024 x 1024 data points, filtered by Lorentz to Gauss transformation in u>2 domain (GB = 0.03 LB = -3) and 80° skewed sin" in u), yielding a 2D Fourier transformation 1024 x 1024 data points real spectrum. (Continued on subsequent pages)...

Solid state 13C NMR measurements were performed on a JEOL GSX-270 spectrometer operating at 67.8 MHz equipped with a CP/MAS accessory. The field strength of the H decoupling was 1.2 mT, contact time 2 ms, repetition time 5s, and spectral width 27.0 kHz. 8K data points were used. Samples was placed in a cylindrical rotor and spun at about 4 kHz. The nC chemical shifts were calibrated indirectly through the adamantane peak(29.5 ppm relative to tetramethylsilane, TMS, (CH3)4Si). 

Fig. 4. 50 MHz DD/MAS 13C NMR spectrum of bulk polyethylene with a viscosity-average molecular weight of 3.0 x 106 at room temperature. The spectrum was obtained by pulse sequence I with a repetition time, X( = 17,000 s. The chemicalshift is based on that of tetramethylsilane (TMS)...

NMR measurement. VT- Si CP/MAS NMR spectra were obtained at temperatures from -120°C (153 K) to 120°C (393 K) using a JEOL GX270 spectrometer equipped with a variable-temperature CP/MAS accessory operating at 53.54 MHz.The sample was contained in a cylindrical-type rotor and spun at 4-5 kHz. Contact time was 5 ms and repetition time 15 s. Spectral width and data points were 10 kHz and 8 k, respectively. Spectra were usually accumulated ca. 200-300 times to achieve a reasonable signal-to-noise ratio. Si chemical shifts were calibrated indirectly through the Si peak of polydi-methylsilane and were converted to the value from tetramethylsilane (TMS). The variable temperature controller was used for all of the probe temperatures at which measurements were taken. 

Photochemical Properties. A simple experiment was performed to compare the photochemical activity of the MP with the TM polymers. Solutions of TM1 and MP1 in quartz cuvettes with the same absorptivity were irradiated with 60 mj cm-2. The UV-Vis spectra before and after irradiation are shown in Fig. 8. A comparison of the absorption bands after 100 pulses shows that about 50% of TM1 and only 20% of MP1 are decomposed. This confirms clearly that the triazene-containing polymers decompose photochemically much more easily than the polymers without this group. It is important to point out that TM1 contains the same structural unit as MP1 (Scheme 3), but with the additional triazene unit in the repetition unit of the polymer. Irradiation of low concentrations of the polymer in solution can be interpreted as pure photochemical decomposition with nearly no thermal influences. 

Fig. 9. Visible range spectral changes during the reduction of soybean Fe(IV) = 0 Lb by GSH. Fe(III) Lb (50 /tM) reacted with H2O2 (100 juM) at pH 7.4 (25 mM KH2PO4/ KOH buffer containing 0.1 mM DTPA). Repetitive scans were recorded 1 min after addition of H2O2 and then at 3-min intervals (reproduced with permission from Puppo, A. Monny, C. Davies, M. J. Biochem. J. 1993, 289, 435-438).

The imaging of conversion within the fixed bed was achieved by using a C distortionless enhancement by polarization transfer (DEPT) spectroscopy pulse sequence integrated into an imaging sequence, as shown in Fig. 44. In theory, a signal enhancement of up to a factor of 4 yuhc, Ji is the gyromagnetic ratio of nucleus i) can be achieved with C DEPT. In this dual resonance experiment, initial excitation is on the H channel. Consequently, the repetition time for the DEPT experiment is constrained by Tm (<7 ic) where is the T relaxation time of... 

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