Tempol

The potential for improved radioprotection by combining Tempol with growth factors such as stem cell factor (SGP), which protects by quite different mechanisms, has been examined in mice (82). Both SGP alone, given 20 and 4 h before and 4 h after TBI, and Tempol alone, given 10 min before TBI, increased 30-day survival, but protection was greater than additive when the two agents were combined. 

Saran M, Winkler K, Fellerhoff B (1997) Hydrogen peroxide protects yeast cells from inactivation by ionizing radiation a radiobiological paradox. Int J Radiat Biol 72 745-750 Sasaki H, Lin L-R, Yokoyama T, Sevilla MD, Reddy VN, Giblin FJ (1998) TEMPOL protects against lens DNA strand breaks and cataract in the X-rayed rabbit. Invest Ophthalmol Vis Sci 39 544-552... 

Figure 15.6 Effects of modulation amplitude on cw-EPR line-shape. Spectra shown were obtained on a Bruker EMX spectrometer equipped with a high-sensitive cavity. The sample was an aqueous solution of tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-l-oxyl) (12.5 fiM, 5 fil) placed in a round glass capillary (0.6 mm ID, 0.8 mm OD Vitrocom, Inc., Mountain Lakes, NJ) sealed at one end. Acquisition parameters listed in Table 15.1 were used, except that the modulation amplitude (M.A.) was varied as respectively indicated for each spectrum. Note that these spectra have not been normalized, and differences in the amplitude of the spectrum are due to the different modulation amplitudes used.

Figure 15.7 Examples of spectral processing. Acquisition parameters listed in Table 15.1 were used to measure a solution of tempol. The background spectrum was collected using water, which shows a feature due to a cavity defect.

Figure 15.8 Examples of spectral integration and normalization. Spectra shown were obtained with nitroxide label 14 (Fig. 15.3C). Acquisition parameters are listed in Table 15.1, except that number of scans = 4 and number of points = 1024. (A) Spectrum of an aqueous sample of a 23-nt RNA, together with its 1st and 2nd integrals. (B) Spectral comparison between a 23-nt RNA (40 gM, dotted line) and a 49-nt RNA (30 jiM, sobd Une). Comparison of the normalized spectra is not skewed by the different amount of labeled RNAs used in the measurement, and reports different nitroxide behavior due primarily to the difference in RNA size. (C) An example of spin counting. The calibration curve was generated by linear fitting (solid Une) of data points (sobd square) obtained using tempol solutions of various concentrations. Using this calibration curve, the sample measured in (A) was found to contain 37.5 gM of spins ( sample = 2.5). Based on an RNA concentration of 40 jiM, the nitroxide labeling efficiency was determined to be 93.6%.

Hydrophilic spin probe 4-Oxo- TEMPO (Sigma) of 0.1 mM concentration was introduced in water dispersions of ShC nanoparticles of different concentrations (0.1, 1.0 and 10 mg/ml). Paramagnetic spin probe like TEMPOL effectively dissolves in hydration water [7,8] owing to capability of polar and paramagnetic NO group of probe to form hydrogen bonds with water molecules. 

SCHEME 12.12 Chemical structure of 2,2,6,6-tetramethyM-hydrox3fpiperidine-AI-oxyl (TEMPOL, N) and biradical (N-O-N). Both S3fmmetric (N-O-N) with isotopes and asymmetric (N-O-N) with N and N isotopes such as those presented in the scheme. ... 

Reactive oxygen species (ROS) scavenger, tempol TGF-(3 impairs renal autoregulation via generation of ROS [233]... 

LeachM, Frank S,Olbrich A, PfellschlfterJ,ThlemermannC Decline in the expression of copper/zinc superoxide dismutase in the kidney of rats with endotoxic shock effects ofthe superoxide anion radical scavenger, tempol, on organ injury. BnJ.Pharmacol. 

Zacharowski K, Olbrich A, Cuzzocrea S, Foster SJ, Thiemermann C Membrane-permeable radical scavenger, tempol, reduces multiple organ injury in a rodent model of gram-positive shock. Crit Care Med. 28 1953-1961,2000... 

An additional probe of the system is the spin label that we have examined by using ESR. The experimental sequence employed is shown in Figure 4. It is well known that coals contain significant amounts of kinetically stable carbon radicals, which yield an ESR spectrum of the type shown in Figure 4(a). In this particular sample of Wyodak coal, weighing about 200 mg, 3.6 x 10 spins were observed. Immediately after, a hexane solution containing the spin label TEMPOL (2,2,6,6-... 

Figure 4. TEMPOL ESR spin label studies in Wyodak coal (a) coal radicals prior to spin label addition (b) ESR spectrum immediately after TEMPOL addition, showing carbon radical in coal and the narrow triplet spin label spectrum (the chemical form of the TEMPOL is indicated in the inset) (c) the narrow TEMPOL spectrum broadens with time.

To study the dynamics of this inclusion process, we measured the variation of the derivative height of the TEMPOL spectrum as a function of time after the spin label addition, and the results are shown in Figure... 

A very rapid reduction of the derivative intensity occurs in the first few minutes after TEMPOL addition, but after that time a much slower rate of change is observed. This behavior may be explained by assuming that some of the TEMPOL molecules are rapidly adsorbed on the surface of the coal and that subsequent loss of TEMPOL from the liquid phase is associated with diffusion of the molecules into the coal matrix. In the case of a simple process one anticipates that diffusion into the coal should exhibit a time dependence. To test this model, we plotted the product of the derivative intensity and as a function of time in Figure... 

Figure 5. Decay of spin label intensity with time (Illinois No, 6 + TEMPOL (in C H ))...

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