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Biomedical subjects

A Hampel

Publications and source records attributed to A Hampel.

49 records · Page 3Linked to original sources
PubMed1976

Altered leucyl-transfer RNA synthetase from a mammalian cell culture mutant.

Altered leucyl-tRNA synthetase from a mammalian cell culture temperature-sensitive mutant, tsHl, was compared with enzyme from normal wild type Chinese hamster ovary cells. The mutant enzyme had a Km for leucine four times larger than that of wild type and enzyme levels 3-10% that of wild type. The presence of tRNA was necessary during in vitro heating of the mutant enzyme to allow expression of thermolability while the presence of tRNA protected wild type enzyme against thermal inactivation. The tsHl enzyme was stable when heated alone or in the presence of tRNA, leucine, and ATP simultaneously. The mutant's enzymes aminoacylated tRNALeu, tRNAVal, and tRNAIle with fidelity in vitro as determined by cochromatography of the amino-acyl-tRNA isoacceptors on RPC-5 reversed phase chromatography. The mutant failed to show any defect other than the direct formation of leucyl tRNALeu by leucyl-tRNA synthetase.

Adenosine Triphosphate↗
PubMed1974

Polyribosomal and particulate distribution of lysyl- and phenylalanyl-transfer ribonucleic acid synthetases.

1. Only two aminoacyl-tRNA synthetases from Chinese hamster ovary cells are found associated with ribosomes and polyribosomes. 2. Phenylalanyl-tRNA synthetase activity is found with the 60S subunit, 80S monoribosome and individual polyribosomes. An additional 15S form of the enzyme is also seen. 3. Lysyl-tRNA synthetase activity is found in a form of about 20S and associated with ribosomal subunits and polyribosomes. The ribosomal subunits having lysyl-tRNA synthetase activity are about 6S larger than the bulk of the ribosomal subunits. 4. The lysyl- and phenylalanyl-tRNA synthetases found in different complexes have differential sensitivity to EDTA and centrifugation properties.

Amino Acids↗
PubMed1968

Single crystals of transfer RNA from formylmethionine and phenylalanine transfer RNA's.

Reproducible conditions have been developed for crystallization of transfer RNA. The conditions may be applicable to many pure transfer RNA species since identical procedures (except for initial transfer-RNA concentration) yielded good crystals from both yeast and Escherichia coli transfer RNA. These crystals, which must be kept at temperatures below about 10 degrees C and handled in vapor of controlled alcohol concentration, have been studied by x-ray crystallography. The availability of crystals of a nucleic acid opens a route for extending knowledge of the tertiary structure of transfer RNA and its relation to important biological functions.

Chemical Phenomena↗
PubMedDate not supplied

Computerized tomographic evaluation of the middle ear and mastoid for posttraumatic hearing loss.

High resolution computerized tomography has been proven valuable in all aspects of temporal bone study. The importance of the procedure in evaluation of traumatic lesions, particularly of the middle ear, has been underemphasized. Damage to the middle ear may occur with blunt trauma, penetrating injury, or barotrauma. Conductive hearing loss and/or CSF otorrhea may result. Detailed evaluation of the ossicles is the hallmark of properly performed computerized tomographic evaluation.

Barotrauma↗
PubMedDate not supplied

Flexible neonatalscope.

Since the introduction of small flexible fiberoptic scopes for the examination of airways, efforts have been made to reduce their size to fit the smallest patients. The first practical scope of this type was the 3.9-mm nasopharyngolaryngoscope introduced in 1975. Modifications over the years have led to the development of the 1.7-mm neonatalscope, primarily designed for the examination of intubated neonates. This neonatalscope has been of great help in determining placement of endotracheal and tracheotomy tubes, as well as in localizing areas of obstruction within the tubes. By means of a special adapter the scope may be used while the patient is on a respirator. Introduction of this new generation of flexible scopes will undoubtedly lead to other valuable and interesting applications of this instrument.

Fiber Optic Technology↗