Caenorhabditis elegans DNA that directs segregation in yeast cells.

We have isolated seven DNA fragments from Caenorhabditis elegans that enhance the mitotic segregation of autonomously replicating plasmids in the yeast Saccharomyces cerevisiae. These segregators, designated SEG1-SEG7, behave like isolated yeast chromosomes: they increase the stability and simultaneously lower the copy number of circular plasmids during mitotic growth in yeast. During meiosis, plasmids containing the C. elegans segregators show higher levels of precocious or aberrant disjunction than do plasmids bearing isolated yeast centromeres. Yet one of the segregators improved the meiotic segregation of the parental plasmid. We estimate that there may be as many as 30 segregator sequences in the C. elegans genome, a value that is consistent with the polycentric nature of C. elegans chromosomes. Five of the seven segregators are linked to sequences that are repeated in the worm genome, and four of these five segregators cross-hybridize. Other members of this family of repetitive DNA do not contain segregator function. Segregator sequences may prove useful for probing the structure of centromeres of both C. elegans and S. cerevisiae chromosomes.     

Why should i comply? Sellers' accounts for (non-)compliance with legal age limits for alcohol sales

Background

Availability is an important predictor of early and excessive alcohol consumption by adolescents. Many countries have implemented age limits to prevent underage purchases of alcohol. However, shop-floor compliance with these age limits appears to be problematic. This study addresses the issue of non-compliance with age limits. Which measures do vendors take to avoid underage alcohol sales, and what do they report as important reasons to comply or not with age limits for alcohol sales?

Methods

Open-ended telephone interviews were conducted with store managers selling alcohol (N = 106). Prior to the interviews, all outlets were visited by an underage mystery shopper in order to measure compliance with the legal age limits on alcohol sales. The interview results are compared against actual compliance rates.

Results

Several measures have been taken to prevent underage sales, but the compliance level is low. Furthermore, open coding resulted in 19 themes, representing both valid and invalid arguments, that vendors mentioned as relevant to their decisions of whether to comply with the law. Compliance with age limits is dependent on the knowledge of the rules and the ability and motivation to follow the rules. The ability aspect in particular seems to be problematic, but in many cases, the motivation to actively comply with the age limits is lacking.

Conclusions

To enhance compliance, it is important to raise the awareness of the importance of age limits and to connect possible violations of the regulations to negative consequences.     

Analytic microdosimetry for radioimmunotherapeutic alpha emitters.

Analytic microdosimetry using Fourier transform techniques has been applied to internal alpha emitters. These techniques need revision and simplification for use with short-lived radionuclides such as those which may be useful for radioimmunotherapy. Analytic methods may have advantages over Monte Carlo methods in some cases (e.g., where time is important). Applications to eight different source geometries show the usefulness of these techniques. Comparisons of some of the results of Monte Carlo calculations prove its accuracy. For a uniform source of 5.867-MeV alphas spread throughout the volume outside a cell surface, the two methods agree well. Results are within 1% both for the average specific energy and for the number of hits. Analytic microdosimetry provides an alternate method to use for the critical evaluation of models that seek to predict the relation between alpha energy deposition and cell survival data. Similarly, it may be helpful to point the way toward the rational interpretation of general biological results for antibodies labeled with alpha emitters.     

Vertebral bone density in children: effect of puberty

To determine changes in bone density during growth, trabecular vertebral density and an index of spinal cortical bone were measured with quantitative computed tomography in 101 children. The children were divided by age into three groups: prepubertal, indeterminate, and pubertal. Compared with prepubertal children, pubertal adolescents had significantly higher trabecular bone density and more compact bone in the spine (P less than .001). After controlling for puberty, vertebral bone density failed to correlate significantly with age, sex, weight, height, surface area, and body mass index. The results indicate that bone density increases markedly during puberty.     

Acrylic resin-fiber composite—part I: The effect of fiber concentration on fracture resistance

This study tested the effect on the fracture resistance of acrylic resin test specimens when different amounts of fibers were incorporated in the resin matrix. The fibers used included glass, carbon, and aramid fibers, with 30 test specimens of each concentration of fibers. Transverse sections of the specimens were studied by scanning electron microscope to establish how the fibers behave in the polymerization process. The results indicated that an increase in the amount of fibers enhanced the fracture resistance of the test specimens (p < 0.001). The SEM micrographs of transverse sections of test polymerized specimens revealed void spaces of different sizes inside the fiber roving.     

Discoid lupus erythematosus-like lesions and stomatitis in female carriers of X-linked chronic granulomatous disease

The skin and oral mucosa were studied in an unselected series of carriers of X-linked chronic granulomatous disease, a hereditary condition in which phagocytic cells display a pronounced functional defect. Three carriers had discoid lupus erythematosus (DLE)-like skin lesions which histopathologically were consistent with DLE of the hypertrophic and profundus type. Four patients had experienced photosensitivity in childhood. Seven patients had recurrent aphthous-like stomatitis which should be distinguished from the recurrent aphthous stomatitis seen in otherwise healthy individuals. The remarkably high incidence of DLE-like symptoms in heterozygous carriers might be related to the presence of mixed populations of defective and normal phagocytes. The variable expression of skin symptoms may be related to uneven distribution of abnormal to normal phagocytes. Female patients with these clinical symptoms, especially the combination of DLE-like skin lesions and aphthous-like stomatitis, should be suspected of being carriers of chronic granulomatous disease and studies of phagocyte function in vitro should be performed, since the diagnosis of the carrier state is of utmost importance for genetic counselling before pregnancy. In order to describe in greater detail the clinicopathological findings and their frequency of expression in the skin and oral mucosa, we have undertaken a prospective study of nine unselected known carriers of X-linked CGD.