No abstract

A total of 18 healthy subjects (9 men and 9 women) 20-35 years of age were used to study the effect of vibration frequency on finger blood flow. Seven vibration frequencies of 16, 31.5, 63, 125, 250, 500 and 1,000 Hz, at vibrational accelerations of 10 m/s2 (rms: root mean square) or 50 m/s2 (rms), with the exception of 16 Hz, which was measured at only 10 m/s2 (rms), were randomly applied to the palm of the right hand for 1 min at intervals of about 3 min. Finger blood flow was measured simultaneously in both the right and the left middle fingers with a blood flowmeter using a thermal diffusion method and in the left middle finger with a laser Doppler flowmeter. The experiments were performed in an artificial climate chamber set at 23 degrees C air temperature and 50% humidity. Relatively great responses were observed at frequencies of 31.5-63 and 250-500 Hz on the exposed and unexposed sides, respectively, as measured with a blood flowmeter using a thermal diffusion method and at 31.5-63 as well as 500 Hz on the unexposed side with a laser Doppler flowmeter. These results may be related to Meissner's and pacinian corpuscles.

A number of compounds used for cancer chemotherapy exert their effects by inhibiting DNA replication. New inhibitors of DNA polymerases, therefore, could be potential candidates for new anti-cancer drugs. This study tested the effects of two phenalenone-skeleton-based compounds, which were isolated from a marine-derived fungus Penicillium sp., sculezonone-B (SCUL-B) and sculezonone-A (SCUL-A), upon DNA polymerase activity. Both compounds inhibited bovine DNA polymerases alpha and gamma, moderately affected the activity of DNA polymerase epsilon, and had almost no effect on HIV-reverse transcriptase and an E. coli DNA polymerase I Klenow fragment. Most notably, whereas SCUL-A inhibited pol beta (IC(50) = 17 microM), SCUL-B has only a weak influence upon this polymerase (IC(50) = 90 microM). Kinetic studies showed that inhibition of both DNA polymerases alpha and beta by either SCUL-A or SCUL-B was competitive with respect to dTTP substrate and noncompetitive with the template-primer. Whereas pol alpha inhibition by SCUL-B is competitive with respect to dATP, the inhibition by SCUL-A was found to be a mixed type with dATP substrate. The K(i) values of SCUL-B were calculated to be 1.8 and 6.8 microM for DNA polymerases alpha and gamma, respectively. The K(i) of DNA polymerase beta for SCUL-A was 12 microM and that for DNA polymerase alpha, 16 microM. Therefore, deletion of the OH-group at C12 enhanced inhibition of DNA polymerase beta. Since computational analyses of these two inhibitors revealed a remarkable difference in the distribution of negative electrostatic charge on the surface of molecules, we infer that different electrostatic charges might elicit different inhibition spectra from these two compounds.