Dose dependent yield

Using optical absorption spectroscopy, we have studied the dose-dependent yield of cryoradiolytic reduction of the metmyoglobin at a broad protein concentration range 0.01-5 mM.66 The yield reached 50% after 2Mrad, was higher than 90% at 16Mrad total dose, and remarkably was the same within the error for all protein concentrations studied. 

The cytotoxic and photocytotoxic effects of two water-soluble fullerene derivatives, a dendritic CL mono-adduct and the malonic acid CL tris-adduct were tested on Jurkat cells when irradiated with UVA or UVB light (Rancan et al., 2002). The cell death was mainly caused by membrane damage and it was UV dose-dependent. Tris-malonic acid fullerene was found to be more phototoxic than the dendritic derivative. This result is in contrast to the singlet oxygen quantum yields determined for the two compounds. 

Alanine dosimeters are based on the ability of 1-a alanine (a crystalline amino acid) to form a very stable free radical when subjected to ionizing radiation. The alanine free radical yields an electron paramagnetic resonance (EPR) signal that is dose dependent, yet independent of the dose rate, energy type, and relatively insensitive to temperature and humidity. Alanine dosimeters are available in the form of pellets or films and can be used for doses ranging from 10 Gy to 200 kGy. A reference calibration service using the alanine EPR system was developed and the scans were sent to the service center by mail. Currently the available system allows transferring the EPR scan to a NIST server for a calibration certificate. This way the procedure has been shortened from days to hours. ... 

The root bark of the cultivated mulberry tree was extracted successively with n-hexane, benzene, and methanol. The methanol extract, 1—20 mg, showed a dose-dependent decrease in arterial blood pressure in pentobarbital-anesthetized rabbit, Fig. (4). The extract was fractionated successively by silica gel column chromatography (C.C.), polyamide C.C., silica gel preparative (p.) TLC, and p. HPLC leading to isolated of kuwanons G (1,0.2% yield) [9] and H (2,0.13% yield) [10]. 

The synthesis of indolizidinone STM (Scheme 15) involved a transannular amidomercuration of lactam 38. Subsequent stereospecific reductive trapping with acrylonitrile afforded the key indolizidinone 39 in 56% yield 85 Further manipulation provided 37 which antagonized, in a dose-dependent fashion, the stimulatory effect of tuftsin in an opsonized sheep red blood cell assay. 

In summary, DMH and AOM failed to increase in vitro mutagenic frequency with or without liver extracts. However, MAM caused a dose-dependent increase in reversion frequency without hepatic enzymes as expected since MAM decomposes heterolytically to methyl-diazonium and formaldehyde (32). Methyldiazonium ions yield nitrogen and methylcarbonium, a powerful alkylating agent. Formaldehyde is oxidized to (X. In contrast to in vitro conditions, the host-mediated assay showed that intact animals converted DMH and AOM to mutagenic products. 

The yield of carbonyl and peroxy compounds (Table XV) is dose-dependent up to a limiting value of G (the number of reacting molecules), which is 12.6 and 3.5 per 100 eV of radiation energy absorbed, respectively. Estimation of total carbonyl compounds and peroxides may provide an appropriate indicator for irradiation control in the sterilization of foods and drugs containing starch. 

Oral bioavailability of mibefradil is dose dependent and ranges from 37% to over 90% with doses of 10 mg or 160 mg, respectively. The plasma half-life is 17 to 25 hours after multiple doses, and it is more than 99% protein bound (15). The metabolism of mibefradil is mediated by two pathways esterase-catalyzed hydrolysis of the ester side chain to yield an alcohol metabolite and CYP3A4-catalyzed oxidation. After chronic dosing, the oxidative pathway becomes less important and the plasma level of the alcohol metabolite of mibefradil increases. In animal models, the pharmacological effect of the alcohol metabolite is about 10% compared to that of the parent compound. After metabolic inactivation, mibefradil is excreted into the bile (75%) and urine (25%), with less than 3% excreted unchanged in the urine. 

Like tasquinimod, linomide yields robust and consistent in vivo growth inhibition of prostate cancer models due to its antiangiogenic activity, and it inhibits of autoimmune encephalomyelitis models of multiple sclerosis (MS). MS clinical trials were discontinued because of unacceptable toxicity, due to dose-dependent induction of proinflammation [35]. 

The dose-dependent term of the phase relaxation is attributed to the electron spin-spin interaction as described in the preceding section. By taking the dose-yield curve shown in Fig. 3 into account, the dose-dependent rate constant can be empirically expressed as... 

Fig. 3. Locomotor hyperactivity to drugs activating forebrain dopamine systems (schematic illustration of response). A. Moderate doses of amphetamine induce progressive dose-dependent increases in counts recorded in automated activity chambers. B. At higher dose, amphetamine induces stereotypy which competes with the expression of locomotion resulting in a suppression of activity counts at peak dose. C. Competing stereotypy yields an inverse U function in the dose response curve (total activity over 2 h test). D. The dopamine receptor agonist apomorphine also increases activity at moderate doses which is blocked by competing stereotypy at high dose, but this drug also inhibits activity at the lowest doses, believed to be due to selective action at presynaptic autoreceptors (see text).

Rzad and Schuler" studied the radiation chemistry of a solution of " C-cyclopropane in hexane over the concentration range 10 " to 10 M. The main radioactive products, which appear to result from ion molecule reactions, are propane formed by H2 transfer (50 %) and by H transfer (20 %) and mixed nonanes (30 %) formed by the addition of CaHg unit to a hexyl ion. At the lower concentrations, very pronounced dose dependence of the yields was observed. This was ascribed to a competitive formation of olefins in the radiolysis. For cyclopropane-cyclohexane solutions the chemical processes seem to be considerably more complicated. The observed yield of total radioactive products extrapolated to zero concentration of cyclopropane are 0.05 and 0.11 G units for hexane and cyclohexane, respectively. These limiting yields are of the order of magnitude of and appear to be related to, the free ion yields in these systems. Since cyclopropane was found to react with hydrocarbon ions" it is used quite often as a scavenger for positive ions, as in the work of Davids and coworkers . 

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