Search

Essential hypertension is associated with structural alterations in the microvessels; in particular, an increase in the media thickness to internal lumen ratio of small resistance arteries (MLR) and a reduction in capillary density have been observed. The evaluation of the morphological characteristics of small resistance arteries in humans is challenging. The gold-standard method is generally considered to be the measurement by wire or pressure micromyography of MLR of subcutaneous small vessels obtained by local biopsies. However, noninvasive techniques for the evaluation of retinal arterioles were recently proposed; in particular, 2 approaches, scanning laser Doppler flowmetry (SLDF) and adaptive optics (AO), seem to provide useful information. Both of them provide an estimation of the wall to lumen ratio (WLR) of retinal arterioles. Moreover, a noninvasive measurement of basal and total capillary density may be obtained by videomicroscopy/ capillaroscopy. It has been recently demonstrated that AO has a substantial advantage over SLDF in terms of evaluation of microvascular morphology, since WLR measured with AO is more closely correlated with the M/L of subcutaneous small arteries. The possibility to noninvasively assess in a reliable way, microvascular morphology in a clinical setting may represent a major advancement, since micromyography has substantial limitations in its application due to the local invasiveness of the procedure. [ABSTRACT FROM AUTHOR]

The aim of the present work was to investigate the possible interference of cytochalasin B (cyt B) with low concentration treatment with colchicine in the induction of chromosome/chromatid loss and micronuclei in human lymphocytes mitotically activated in vitro. Thus, cells from a single female donor were treated with colchicine (10 or 25 nM, from 24 h after PHA addition to fixation at 66 h) either in the presence or absence of cyt B. Single lagging chromosomes/chromatids were scored in bipolar ana-telophases and greater damage (disrupted and c-anaphases) was scored in cells at anaphase. Micronuclei were scored in the first 4000 nuclei observed in both cyt B-treated (in mononucleate and binucleate cells) and untreated cultures. With the same criterion, FISH analysis was performed on 2000 nuclei where chromosome 7 and 11 centromeric DNA probes were used in pairs. Our results showed that: (i) the frequency of laggards and of micronuclei increased with colchicine concentration but in the presence of cyt B there was a lower frequency of both (with a mean reduction of ~49%); (ii) FISH analysis showed a colchicine concentration-dependent increase in nuclei with three spots for chromosome 7; (iii) a colchicine concentration-dependent increase in tetraploid cells was observed. This increase was particularly remarkable (5-fold) in cells grown in the presence of cyt B compared with cyt B-untreated cells. The observed `cyt B effects' can be explained if it is assumed that in cytokinesis-blocked cells there is a shorter distance between the poles. As a consequence: (i) laggards would be engulfed in the nearest daughter nucleus with a consequent lower induction of micronuclei; (ii) segregating sister chromatids in heavily impaired anaphases would not travel a sufficient distance to give rise to two daughter nuclei, leading to an increased frequency of polyploid nuclei. [ABSTRACT FROM PUBLISHER]