Influence of dihydropyrimidine dehydrogenase gene (DPYD) coding sequence variants on the development of fluoropyrimidine-related toxicity in patients with high-grade toxicity and patients with excellent tolerance of fluoropyrimidine-based chemotherapy.

Alterations in dihydropyrimidine dehydrogenase gene (DPYD) coding for the key enzyme (DPD) of fluoropyrimidines (FPs) catabolism contribute to the development of serious FPs-related toxicity. We performed mutation analysis of DPYD based on cDNA sequencing in 76 predominantly colorectal cancer patients treated by FPs with early development of high (grade 3-4) hematological and/or gastrointestinal toxicity. Six previously described [85T>C (C29R), 496A>G (M166V), 775A>G (K259E), 1601G>A (S534N), 1627A>G (I543V), IVS14+1G>A, 2194G>A (V732I)] and two novel [187A>G (K63E) and 1050 G>A (R357H)] non-synonymous DPYD variants were found in 56/76 (73.7%) high-toxicity patients. Subsequently, these alterations were analyzed in 48 patients with excellent long-term tolerance of FPs and in 243 controls and were detected in 37/48 (77.1%) and 166/243 (68.3%) cases, respectively. Analysis of these alterations as risk factors for development of toxicity in pooled FPs-treated population demonstrated that C29R negatively correlated with overall gastrointestinal toxicity (OR = 0.48; 95%CI 0.23-1.0) and M166V in women protected against overall hematological toxicity and neutropenia (both OR = 0.26; 95%CI 0.07-0.89), whereas IVS14+1G>A (found in five high-toxicity patients only) increased risk of mucositis in overall population (OR = 7.0; 95%CI 1.1-44.53), and thrombocytopenia in women (OR = 10.8; 95%CI 1.24-93.98). Moreover, we identified a strong association of V732I with leucopenia (OR = 8.17; 95%CI 2.44 - 27.31) and neutropenia (OR=2.78; 95% CI 1.03-7.51). Our data enabled characterization of "high risk" haplotypes (carriers of IVS14+1G>A or V732 lacking M166V) representing small (22% female and 11% male patients), population in high risk of serious hematological toxicity development, and in patients with "lower risk" that unlikely develop serious hematological toxicity [carriers of M166V without IVS14+1G>A and V732I in females (32% women), and non-carriers of C29R, M166V, IVS14+1G>A, and V732I in males (46% men)]. Our results indicate that genotyping of several DPYD variants may lead to stratification of patients with respect to the risk of serious hematological toxicity development during FPs treatment.

[The effect of ionizing radiation on enzymes. X. The effect of gamma irradiation on pancreatic amylase in pancreatin]. / Ucinek ionizujícího zárení na enzymy. X. Vliv zárení gama na pankreatickou amylázu v pankreatinu.

The present paper examined the effect of ionizing radiation (source, 60Co) within a range of doses from 10 to 120 kGy on amylolytic efficacy of pancreatin of two types: pancreatin obtained by isolation from an extract of the pancreas (sample 1) and pancreatin containing parts of the pancreatic tissue, but with higher amylolytic efficacy (sample 2). Efficacy was expressed in F.I.P. units. As shown in the chart, a percentual decrease in efficacy is higher in the more active sample 2. Graphical representation is in good agreement with the statistical evaluation of the significance between the decreases in efficacy in both samples irradiated with doses of 30 and 120 kGy, if the median test was used and probability was calculated with the use of Fisher's test. This is not, however, the case of irradiation with a dose of 10 kGy. The residual, graphically corrected efficacy after irradiation with a sterilizing dose of 25 kGy was 84.1% (sample 1) and 80.3% (sample 2). With the maximal dose used, the residual efficacy was 43.7% (sample 1) and 36.7% (sample 2).

[The effect of ionizing radiation on enzymes. VI. The effect of gamma irradiation on the proteolytic activity of pepsin derived from porcine gastric mucosa]. / Ucinek ionizujícího zárení na enzymy. VI. Vliv zárení gama na proteolytickou úcinnost pepsinu z veprové zaludecní sliznice.

The present paper examines the effect of gamma radiation on the proteolytic effectiveness of pepsin of an activity of 6640, 8940 and 11,333 units in 1 g, expressed according to the Czechoslovak Pharmacopoeia. The samples were irradiated with graded doses from 5.2 to 128.7 kGy so that the course of inactivation could be determined. Effectiveness was determined six times in each sample and parallel experiments were statistically evaluated. The results are shown in Tables 1 to 3. The relative width of the interval of reliability only exceptionally exceeds 5%. A decrease in effectiveness shown in Fig. 1 shows that the course of the decrease in effectiveness did not depend in the interval used on the initial activity of the enzyme. In the semilogarithmic arrangement in Fig. 2, the dependence of the decrease in effectiveness on the dose possesses a linear course. The decrease in effectiveness in dependence on the dose of radiation can be approximately read in the graph in Fig. 3. The Czechoslovak Pharmacopoeia prescribes a dose of 24 kGy to achieve sterility by means of ionizing radiation. When microbiological indefectibility is the case, a smaller dose suffices, depending on the level of the initial contamination and the resistance of the present microorganisms. It usually does not exceed 10 kGy, in our case even 5 kGy. Nevertheless, there occurs a loss of effectivity, in the extreme case 10-13%. The largest dose used in the present paper decreased effectiveness by 60%. If ionizing radiation is to be used to decontaminate pepsin, a certain decrease in activity must be taken into account. In addition, a toxicological evaluation must be recommended.