Repetitive DNA sequence families in Crepis capillaris

Three families of tandemly repetitive DNA from Crepis capillaris were cloned and characterized. Data obtained from in situ hybridization indicate that these families are located mainly in the heterochromatic C-bands. The pCcH32 family hybridizes at the paracentromeric C-band of the NOR (nucleolus-organized region) chromosome and along most of the long arm of the same chromosome. The pCcD29 family is located in all the remaining C-bands of the karyotype, while the third family, pCcE9, is restricted to the more proximal C-bands. Nucleotide sequence comparisons between one cloned repeating unit from each DNA family showed some significant regions of homology between the families. We discuss the sequence relationships between the three DNA families and the significance of our data in relation to models of heterochromatin evolution, emphasizing the concepts of equilocality and the differentiation of the NOR-bearing chromosome. We also examine the possible role that chromosome disposition, in either mitotic or meiotic nuclei, plays in the distribution and homogenization of heterochromatic DNA sequences.     

The numerical analysis of dovetail joints

A technique for the numerical analysis of dovetail joints is presented which is capable of modelling relative motion at the interface of the assembly. The method is shown to give results in good agreement with experimental data and provide a basis for the study of interface motion in contacting assemblies.     

Effects of intermittent ozone exposure on peak expiratory flow and respiratory symptoms among asthmatic children in Mexico City

PURPOSE: The purpose of this research was to study adolescents' perceptions of violence in their communities and schools and examine the relationship between these reports and their emotional and behavioral functioning, controlling for the effects of family violence and other sociodemographic variables. METHODS: Respondents included 935 urban and suburban high school students who completed the Youth Self-Report (YSR) as well as measures assessing their perceptions of community, school, and family violence. RESULTS: This sample of high school students was exposed to high levels of violence in their communities and schools. Over 45% of the students reported witnessing severe forms of violence such as a shooting or stabbing in their communities or schools during the year prior to the study. Hierarchic regression analyses revealed that for males, exposure to community and school violence was a significant predictor of aggressive acting-out behaviors, even when controlling for the effects of family violence and other sociodemographic variables. For girls, only exposure to school violence was a significant predictor of aggression. The results for internalizing scores (depression, withdrawal) were less impressive, particularly for males. CONCLUSIONS: The high levels of violence exposure of adolescents in their communities and schools and the associated increase in behavior problems suggest the need for developing school and community intervention programs to treat violence and its impact.     

Real-time ultrasonic monitoring of fiber-matrix debonding in ceramic-matrix composite

Real-time ultrasonic techniques were developed for monitoring damage in a unidirectional ceramic-matrix composite under longitudinal tensile loading. Specifically, shear-wave transducers producing waves polarized in the transverse to the fiber direction were used in contact with the specimen to detect the initiation and propagation of fiber—matrix debonding, and to determine the transverse shear modulus and its degradation. The ultrasonically measured transverse shear modulus and its degradation was in reasonably good agreement with a prediction based on a modified shear lag model and interpolation between available solutions for fully bonded and fully unbonded fibers.     

A corneal endothelium cell analyzer for slit lamps

An optical system that attaches to a slit lamp is an alternative to the cost and limitations of specular microscopes. In order to overcome the limitations of subjective assessment of all the endothelial layers, the difficulties of manipulation, high cost, and analysis of several parts of the cornea, we have developed a system that can be attached to the slit lamp (290/spl times/ nominal magnification of the image of the cells displayed on a PC monitor and a dedicated software for image treating and cells counting). Results are in good agreement with measurements done in specular microscopes (correlation coefficient is 0.98081) and the automatic counting method is also in good agreement with the interactive counting method (correlation coefficient is 0.95798).     

Small cell carcinoma of the bladder. Report of a new case

Contribution of a case report of vesical small cell carcinoma (SCC) seen at our Centre and managed with partial cystectomy and systemic chemotherapy (CMT) with M-VAC. SCC is an uncommon neoplasia of the bladder usually associated with an aggressive behaviour. The effectiveness of radical surgery has not been demonstrated, so a conservative treatment was chosen which has allowed to preserve a high quality of life until now, 36 months after diagnosis. The studies of local and distant relapses show no signs of residual disease.     

Polarographic determination of the catalytic rate constants of dehydration of some dicarbonyl compounds in strong acid medium

The i_L-t relationship corresponding to the CE mechanism is checked in the reduction of glyoxal, methyl-glyoxal and diacetyl. From this equation taking into account the specific acid catalysis of the dehydration reactions, the catalytic rate constants of both non-catalyzed and proton-catalzed reactions are calculated.     

Myocardial uptake and redistribution of 99mTc-N-NOET in dogs with either sustained coronary low flow or transient coronary occlusion: comparison with 201Tl and myocardial blood flow

BACKGROUND: 99mTc-N-NOET (NOET) is a new myocardial perfusion imaging agent that redistributes over time. We sought to better define the redistribution kinetics of NOET using open-chest canine models of sustained low coronary flow (protocol 1) and transient coronary occlusion followed by reflow (protocol 2). METHODS AND RESULTS: In protocol 1 (n=10), NOET and 201Tl were injected during low flow in the left anterior descending coronary artery (LAD) that was sustained for 2 hours. Protocol 2 dogs (n=6) were injected with NOET during 20 minutes of LAD occlusion followed by 2 hours of reflow. In both protocols, serial NOET planar images were acquired, and myocardial flow and 2-hour tracer activities were determined by gamma-well counting. Defect resolution was observed on images in both protocols. Initial defect count ratios, reflecting flow disparity at injection (0.66+/-0.03 and 0.57+/-0.04, respectively), increased over 2 hours (0.73+/-0.02 and 0.75+/-0.04, respectively; P<.001 versus initial). Quantitative imaging showed that NOET redistribution resulted from greater clearance from normal areas versus low-flow or transiently occluded areas. In protocol 1, 2-hour NOET and 201Tl stenotic-to-normal tissue activity ratios were similar (0.76+/-0.06 versus 0.73+/-0.04, P=NS) and higher than injection flow ratios (0.52+/-0.06 and 0.56+/-0.07, respectively, P<.001), consistent with tracer redistribution. In protocol 2, NOET redistributed to an even greater extent (injection flow ratio, 0.27+/-0.04; 2-hour tissue activity ratio, 0.84+/-0.03, P<.001). CONCLUSIONS: NOET is the first 99mTc-labeled myocardial imaging agent with kinetics similar to 201Tl in experimental models, permitting redistribution imaging. NOET appears to be a promising agent for assessing patients with coronary artery disease.