A noncomputerized count-based technique for the determination of resting left ventricular ejection fraction

A noncomputerized, count-based technique for the determination of left ventricular ejection fraction (LVEF), which does not use geometric assumptions of left ventricular shape, was developed. The noncomputerized technique and computerized multigated ventriculography using both fixed and variable region-of-interest (ROI) methods were performed on 16 patients. The LVEFs obtained with the noncomputerized technique correlated well with both the fixed ROI computerized technique (r = .87) and the variable ROI computerized technique (r = .86). It is concluded that when a computer is not available, the noncomputerized technique is a valid alternative for the determination of LVEF in resting patients in stable sinus rhythm.     

The acid deoxyribonuclease of neutrophils: a possible participant in apoptosis-associated genome destruction

Human neutrophils are terminally differentiated cells that spontaneously undergo apoptosis in tissue culture. Apoptosis in these cells can be delayed by culture in the presence of granulocyte colony- stimulating factor or other inflammatory mediators. Neutrophils were found to contain an acid endonuclease that appeared to be responsible for the internucleosomal DNA cleavage that accompanies apoptosis. As measured by a plasmid nicking assay, this endonuclease had a molecular weight (M(r)) of 35,000, a pH optimum of 5.5, and a threshold for activity of pH 6.6 to 6.8. It was weakly inhibited by divalent cations (Ca2+, Mg2+, and Zn2+) and more strongly inhibited by aurintricarboxylic acid and N-bromosuccinimide. DNA from neutrophils treated with nigericin in buffers of defined pH displayed nucleosomal ladders whose prominence varied with pH in a manner that paralleled the pH dependence of the plasmid cleavage assays, consistent with internucleosomal DNA cleavage by the acid endonuclease. We have previously shown that neutrophils undergo acidification to a pH value as low as 6.0 during apoptosis; we suggest that this endonuclease may be responsible for the DNA cleavage seen in apoptotic neutrophils.     

Identification and elimination of DNA sequences in Taq DNA polymerase.

This study confirms that different preparations of Taq DNA polymerase are contaminated with eubacterial DNA. The contaminants appeared to represent more than one strain or species but were not identified as Thermus aquaticus or Escherichia coli. Differences in microcentrifuge tube composition appeared to affect elimination of the contaminants.     

Positron emission tomography and central neurotransmitter systems in movement disorders

Summary— This article discusses the anatomical and neurochemical structure of the basal ganglia and reviews the Positron Emission Tomographic (PET) ligands available for investigating these pathways. We discuss how clinical PET studies have improved our understanding of the neurochemical changes underlying principal movement disorders.     

Oxygen tension in human tumors: in vivo mapping using CT-guided probes

The role of oxygen in tumor response to therapy has been studied for several decades. We describe a technique that allows in vivo measurement of oxygen in tumors using computed tomography to guide probes. In the evaluation of 16 tumors, oxygen tensions were found to be substantially lower than surrounding tissue and varied nonrandomly. This technique has allowed construction of detailed tumor oxygen level maps.