The small GTP-binding protein rho regulates cortical activities in cultured cells during division

We have investigated the role of the small GTP-binding protein Rho in cytokinesis by microinjecting an inhibitor, C3 ribosyltransferase, into cultured cells. Microinjection of C3 into prometaphase or metaphase normal rat kidney epithelial cells induced immediate and global cortical movement of actin toward the metaphase plate, without an apparent effect on the mitotic spindle. During anaphase, concentrated cortical actin filaments migrated with separating chromosomes, leaving no apparent concentration of actin filaments along the equator. Myosin II in injected epithelial cells showed a diffuse distribution throughout cell division. All treated, well-adherent cells underwent cleavage-like activities and most of them divided successfully. However, cytokinesis became abnormal, generating irregular ingressions and ectopic cleavage sites even when mitosis was blocked with nocodazole. The effects of C3 appeared to be dependent on cell adhesion; less adherent 3T3 fibroblasts exhibited irregular cortical ingression only when cells started to increase attachment during respreading, but managed to complete cytokinesis. Poorly adherent HeLa cells showed neither ectopic cleavage nor completion of cytokinesis. Our results indicate that Rho does not simply activate actin-myosin II interactions during cytokinesis, but regulates the spatial pattern of cortical activities and completion of cytokinesis possibly through modulating the mechanical strength of the cortex.     

Involvement of the 5'' proximal coding sequences of hepatitis C virus with internal initiation of viral translation

To examine patterns of identity development for late adolescents raised in the Norwegian mixed liberal welfare-state economic system compared with late adolescents raised in the free-market economic system of the United States, ego identity status scores and distributions were examined for 56 (37 women, 19 men). Norwegian and 1498 (814 women, 684 men) United States undergraduate university students using the Extended Objective Measure of Ego Identity Status-2. The United States sample was drawn from four geographic regions and comprised of those who had participated in prior studies performed by Adams. Significant differences were found between the two nations on all identity status subscales in the ideological and interpersonal domains for each sex. The more moderate identity status scale scores evidenced by the Norwegian sample may reflect a cultural trend toward greater moderation in the exploration and commitment process.     

Performance of some diagnostic systems in the prediction of occlusal caries in permanent molars in 6- and 11-year-old children

Until late in gestation, fetal spontaneously hypertensive rat (SHR) is growth retarded. Fetal growth rate increases after placental hypertrophy occurs between fetal days 18 and 20. The increase in placental mass may result in improved transfer of macro nutrients to the fetus and thus stimulate growth. In this study, fetal and placental uptake of the glucose analog 3-O-methyl glucose (3MG) and the amino acid analog amino-isobutyric acid (AIB) from the maternal circulation were compared in the SHR and Wistar-Kyoto (WKY) on days 16, 20 and 22 of gestation. Placental 3MG uptake (d/min/g tissue wet weight) was decreased in the SHR on days 20 and 22 but no differences were observed in fetal 3MG uptake. Increased placental mass in the SHR meant that total placental 3MG uptake was greater in the SHR. Placental uptake of AIB (d/min/g tissue wet weight) was much lower in the SHR (on days 16, 20 and 22) and the decrease was not compensated for by increased placental mass. Fetal uptake of AIB was decreased on days 20 and 22 (P<0.05). AIB uptake (d/min/g tissue wet weight) by the carcass and the internal organs (brain, heart, kidney, liver and lung) was also lower in the SHR. These findings indicate that although fetal growth in the SHR increases rapidly in late gestation following placental hypertrophy, it does so despite a pronounced deficit in amino acid uptake.     

Cervical ecchordosis physaliphora: CT and MR features

We report a case of cervical ecchordosis physaliphora in an elderly man who presented with hemihypoaesthesia and contralateral hemiparesis. MRI showed a well defined, non-enhancing extradural mass lesion on the dorsal surface of the odontoid process of the axis. The lesion was of intermediate signal intensity on T1 weighted images and of low signal intensity on T2 weighted images. CT showed a small bony defect on the adjacent cortex of the odontoid process. Recognition of the imaging features of ecchordosis physaliphora is helpful in suggesting the diagnosis and differentiating the lesion from chordoma.     

Age-related deterioration in arterial structure and function in postmenopausal women: impact of hormone replacement therapy

Epidemiological evidence suggests that hormone replacement therapy (HRT) reduces morbidity and mortality from cardiovascular diseases in postmenopausal women. In this study, indices of arterial function [total systemic arterial compliance (SAC) and carotid arterial distensibility coefficient (DC)], structure [carotid intima-media thickness (IMT)], and lipid profiles were compared in postmenopausal women on long-term HRT and aged-matched controls. One hundred nine women aged 44 to 77 years taking HRT and an age-matched group of 108 female controls were entered into the study. The two groups were similar for body mass index, smoking status, exercise level, alcohol intake, and blood pressure. Fasting cholesterol, low density lipoprotein, and lipoprotein(a) were reduced and high density lipoprotein increased in the HRT group. IMT increased with age; SAC and DC were reduced with age in both groups. The HRT group had a higher mean SAC (0.42+/-0.02 versus 0.34+/-0.02 U/mm Hg, P=0.0001) and a lower mean IMT (0.67+/-0.01 versus 0.74+/-0.02 mm, P=0.006) than did controls. Subgroup analysis for estrogen versus estrogen plus progestin revealed no differences for SAC and IMT; DC, however, was greater in estrogen-only users. Smokers on HRT had a higher mean SAC (0.41+/-0.02 versus 0.31+/-0.01 U/mm Hg, P=0.008) and a lower IMT (0.65+/-0.02 versus 0.75+/-0.03 mm, P=0.002) than did smokers not taking such therapy. A protective effect of long-term estrogen therapy on age-related changes in arterial structure and function in postmenopausal women was evident in smokers and nonsmokers alike. Progestin appeared to counteract the effects of estrogen on carotid compliance only. Long-term controlled trials are needed to determine the significance of these findings.     

The Zalpha domain from human ADAR1 binds to the Z-DNA conformer of many different sequences

Z-DNA, the left-handed conformer of DNA, is stabilized by the negative supercoiling generated during the movement of an RNA polymerase through a gene. Recently, we have shown that the editing enzyme ADAR1 (double-stranded RNA adenosine deaminase, type 1) has two Z-DNA binding motifs, Zalpha and Zbeta, the function of which is currently unknown. Here we show that a peptide containing the Zalpha motif binds with high affinity to Z-DNA as a dimer, that the binding site is no larger than 6 bp and that the Zalpha domain can flip a range of sequences, including d(TA)3, into the Z-DNAconformation. Evidence is also presented to show that Zalpha and Zbeta interact to form a functional DNA binding site. Studies with atomic force microscopy reveal that binding of Zalpha to supercoiled plasmids is associated with relaxation of the plasmid. Pronounced kinking of DNA is observed, and appears to be induced by binding of Zalpha. The results reported here support a model where the Z-DNA binding motifs target ADAR1 to regions of negative supercoiling in actively transcribing genes. In this situation, binding by Zalpha would be dependent upon the local level of negative superhelicity rather than the presence of any particular sequence.