Actinomycin D induced DNase I hypersensitivity and asymmetric structure transmission in a DNA hexadecamer

DNase I cleavage rates and nmr chemical shifts are shown to change for DNA sequences distal to an intercalated actinomycin D molecule in a duplex hexadecamer upon drug binding. Both sets of observations suggest that the source of these changes is a DNA-mediated structural response. The nmr results imply the response is transmitted preferentially in a 5'-to-3' direction from the drug binding site. An inequivalent response of the two strands to a ligand-induced conformational change immediately suggests a mechanism for distinguishing the sense and antisense strands of DNA.

Prevalence of age-related cataract in Ganzi and Shanghai. The Epidemiological Study Group

It has been reported that the prevalence of cataract is much higher in plateau than that in plain regions. But the data are incomplete and can not be compared because of different examination methods and different diagnostic criteria. A small group of ophthalmologists was sent to Ganzi, Sichuan Province at the altitude of 3.393 m, and to Qinpu in the suburb of Shanghai which is at the sea level. In Ganzi 3,905 (91.97%) people including 822 Hans and 3,083 Zang and in Qinpu 3,101 (93.20%) were studied. Age-related cataract was diagnosed when there are cortical or nuclear, or mixed opacities; and aphakia due to previous extraction of age-related cataract. Direct method was used to standardize the data. The prevalence of age-related cataract in Ganzi is about 82% higher than that in Qinpu in all age groups; from age 16-60, the prevalence of age-related cataract in Ganzi is about 180% (in Hans) and 160% (in Zangs) higher than that in Qinpu. There is no significant difference in the prevalence of age-related cataract between the ethnic groups in Ganzi. In Ganzi, the sunshine hours per year are 1.28 times that in Qinpu, and the global radiation in Ganzi is 1.47 times that in Qinpu. The higher prevalence of cataract in Ganzi than in Qinpu may be due to the greater exposure to the sunshine on the Tibetan plateau. The differences in prevalence between males and females and between indoor and outdoor work are discussed.

The effect of valproic acid on sister chromatid exchange aberration frequency in epileptic children

Sister chromatid exchange (SCE) and chromosome aberration have been used to examine the peripheral lymphocytes of 20 epileptic children on 6-52 months monotherapy with valproic acid (VPA), and two matched control groups were set for comparison. The frequency of SCE in the VPA treated group is significantly higher than two control groups (P less than 0.01). It seems that the increase in SCE frequency is not related to epilepsy. SCE was also examined in 10 epileptic children before and after intake of only sodium valroat for 6-7 months, there was statistically significant change of SCE following VPA. 9 normal children's lymphocytes were exposed in vitro to sodium valproate (5-20 micrograms/ml), all showed a significant increase in SCE. These results suggested that VPA and its derivatives could damage the DNA of child users; however slightly higher rates of chromosome aberration were not significantly different from two control groups.

The effect of valproic acid on SCE and chromosome aberrations in epileptic children

Sister-chromatid exchange (SCE) and chromosome aberrations have been studied in peripheral lymphocytes of 20 epileptic children treated in monotherapy with valproic acid (VPA) for 6-52 months and in 2 matched control groups. The frequencies of SCE in the VPA-treated epileptic children were significantly higher than in the 2 control groups (p less than 0.01); rates of chromosome aberrations were slightly higher but not significantly different from the 2 control groups. We also examined SCE in 10 epileptic children before and after they took sodium valproate for 6-7 months; there was a statistically significant change in SCE following VPA. 9 normal children whose lymphocytes were exposed in vitro to sodium valproate (5-20 micrograms/ml) showed a significant increase in SCE.

Monoamine metabolites in cerebrospinal fluid during and after acute cerebral ischemia

In order to understand the role of monoamines in cerebral ischemia, 3-methoxy-4-hydroxyphenylglycol(MHPG), 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid(HVA), the three major unconjugated monoamine metabolites in cerebrospinal fluid (CSF), of 33 patients and 18 controls were measured with high performance liquid chromatography. Results showed all three metabolites were raised in patients with severe ischemia, but only MHPG and 5-HIAA were elevated significantly, MHPG changes more quickly and regularly as a consequence of cerebral ischemia than the two others. A positive correlation between any pair of metabolites was found in controls and in patients in the first week after stroke, but not at the end of the second week. Computer assisted multivariate analysis indicated 5-HIAA and MHPG correlated more closely with the state of illness in the acute stage, whereas HVA correlated the least. Possible explanations for the changes of CSF levels of amine metabolites are discussed.

Monoamine metabolites in cerebrospinal fluid during acute cerebral ischemia

To clarify the rule of monoamine in cerebral ischemia, 3-methoxy-4-hydroxyphenylglycol (MHPG), 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) in cerebrospinal fluid (CSF) of 33 patients and 18 controls were measured with high performance liquid chromatography. Results showed all the three metabolites increased in patients with severe ischemia but only MHPG and 5-HIAA increased significantly. MHPG changed more quickly and regularly in cerebral ischemia than the other two. A positive correlation between any couple of the metabolites was found in both the controls and patients in the first week after stroke, but it was disturbed at the end of the second week. Computer-assisted multivariate analysis indicated that 5-HIAA and MHPG are more closely related to the state of illness in the acute stage while HVA the least. Possible explanations for the changes of CSF levels of amine metabolites were discussed.

Actinomycin D induced DNase I cleavage enhancement caused by sequence specific propagation of an altered DNA structure

Two DNA hexadecamers containing one central 5'-GC-3' base step have been examined by footprinting methodology in the presence and absence of actinomycin D. The results of these studies, coupled with imino proton NMR measurements indicate that the antitumor drug causes a change in DNA conformation at a distance from the actinomycin intercalation site in a molecule of sequence d[ATATATAGCTATATAT] that does not occur in d[AAAAAAAGCTTTTTTT]. The experiments demonstrate that DNase I rate enhancements associated with actinomycin D binding are caused by ligand alteration of equilibrium DNA structure.