Relationship between genetic polymorphism of CYP1A1 at codon 462 (Ile462Val) in colorectal cancer.

AIMS AND BACKGROUND: The enzyme cytochrome P450 plays an important role in the metabolization and detoxification of various compounds. CYP1A1 is a polymorphic enzyme and some of its alleles have been correlated with an increased risk of developing various types of cancer. The aim of this study was to investigate the incidence of the polymorphism A-->G (Ile462Val, exon 7) in colorectal cancer patients and the correlation of this polymorphism with others risk factors. PATIENTS AND METHODS: 114 Brazilian patients with colorectal cancer were matched by age and sex to 114 healthy individuals. DNA was extracted from peripheral blood and the genotypes of the polymorphisms were assessed by PCR-restriction fragment length polymorphism. RESULTS: In the case group 64 subjects were male, 53 were alcohol users and 68 were smokers. In the control group 61 were male, 67 were alcohol users and 53 smokers. There were 14 subjects with wild-type homozygous A/A, 97 with heterozygous A/G, and 3 with homozygous mutated G/G in the cancer group versus 81 subjects with wild-type homozygous A/A and 33 with heterozygous A/G in the control group. The presence of the G allele (OR 5.14, 95%CI 3.15-10.80) was associated with an increased risk of colorectal cancer (p=0.001). The prevalence of smokers was higher in the cancer group (p=0.047, OR 1.71, 95%CI 1.03-3.11). CONCLUSION: These results suggest a positive association between the A-->G polymorphism and the risk of colorectal cancer. In addition, smoking was also a colorectal cancer risk. We did not find any correlation between this polymorphism and sex, grade of differentiation, stage, or evolution of the disease.

Stimulated Raman scattering of intense laser pulses in air.

Stimulated rotational Raman scattering (SRRS) is known to be one of the processes limiting the propagation of high-power laser beams in the atmosphere. In this paper, SRRS, Kerr nonlinearity effects, and group velocity dispersion of short laser pulses and pulse trains are analyzed and simulated. Fully time-dependent, three-dimensional, nonlinear propagation equations describing the Raman interaction, optical Kerr nonlinearity due to bound electrons, and group velocity dispersion are presented and discussed. The effective time-dependent nonlinear refractive index containing both Kerr and Raman processes is derived. Linear stability analysis is used to obtain growth rates and phase matching conditions for the SRRS, modulational, and filamentation instabilities. Numerical solutions of the propagation equations in three dimensions show the detailed evolution of the Raman scattering instability for various pulse formats. The dependence of the growth rate of SRRS on pulse duration is examined and under certain conditions it is shown that short (approximately psec) laser pulses are stable to the SRRS instability. The interaction of pulses in a train through the Raman polarization field is also illustrated.

[Radiation therapy and cardiac pacemakers]. / Pacamakers em radioterapia.

The number of patients with cardiac pacemakers submitted annually to radiation therapy is increasing. Radiation therapy causes interference in the normal functioning processes, directly by chemical changes in the structure of the device and also by electromagnetic disturbances generated in the process of treatment. The changes in the technology used in the manufacture of cardiac pacemakers after the 70's, with the introduction of complementary metal-oxide semi-conductors (CMOS) in the circuits, drastically increased the chance of dangerous interference in the normal function of cardiac pacemakers occurring when in contact with an ionizing radiation source. The authors briefly describe the mechanisms underlying the radio-induced damage usually observed. A review of the literature on this issue is made and solutions are pointed out to perform safe radiation therapy and minimize the risk of device malfunction.