We will discuss one possible correlation between the origin of optical activity in biological molecules and the helicity of beta particles emitted in nuclear beta decay. This correlation is based on the supposition of Hrasko and Garay that electrons in optically active molecules possess helicity. Positronium formation experiments are significantly more sensitive to this particular effect than radiolysis experiments although no experiments of any type to date have obtained the sensitivity that our preliminary calculations indicate is necessary. We discuss a new experiment in which positronium is formed in vacuum with a low energy polarized positron beam. An improvement of up to 10(4) in sensitivity to the effect is possible.

Electrons↗

PubMedDate not supplied

Negatively supercoiled simian virus 40 DNA contains Z-DNA segments within transcriptional enhancer sequences.

Three 8-base pair (bp) segments of alternating purine-pyrimidine from the simian virus 40 enhancer region form Z-DNA on negative supercoiling; minichromosome DNase I-hypersensitive sites determined by others bracket these three segments. A survey of transcriptional enhancer sequences reveals a pattern of potential Z-DNA-forming regions which occur in pairs 50-80 bp apart. This may influence local chromatin structure and may be related to transcriptional activation.

Animals↗

PubMedDate not supplied

Clone controversy at Immunex.

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Cloning, Molecular↗

PubMedDate not supplied

Mechanical complications from insertion of subclavian venous feeding catheters: comparison of de novo percutaneous venipuncture to change of catheter over guidewire.

Since a percutaneous catheter insertion into the subclavian vein can be tedious, time consuming, and risky, we have compared the morbidity of 137 de novo subclavian catheter insertions to that of 93 reinsertions over guidewire. Mechanical complications were significantly higher (p less than 0.03) in those with catheter insertions (8.8%) than in those with the guidewire insertions (2.2%). These included pneumothorax (4), arterial puncture (4), catheter-size bleed (3), and hemothorax (1) in the catheter insertion group and local bleeding (1) and hydrothorax (1) in the guidewire insertion group. The difference in complications between methods is probably inherent in the techniques. Operator experience was not a factor: 55% of the physicians in each group had previously done less than 26 subclavian venous catheterizations. Preliminary analysis indicates that the infection rate, as determined by semiquantitative, cultures, is the same in each group. When considering the equal potential for infection, we conclude that change over a guidewire is an acceptable alternative to contralateral de novo percutaneous subclavian venipuncture for feeding catheter insertion. In view of fewer mechanical complications and greater ease of insertion, change of subclavian feeding catheters by guidewire is probably the method of choice.

Arteries↗

PubMedDate not supplied

Reaction stations.

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Allergens↗

PubMedDate not supplied

Transfer RNA and the translation apparatus in the origin of life.

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Biological Evolution↗

PubMedDate not supplied

Left-handed Z-DNA.

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Antibodies↗