Biomedical subjects

I Olson

Publications and source records attributed to I Olson.

3 recordsLinked to original sources

PubMed2002

Helical axis errors affect computer-generated occlusal contacts.

A helical axis describing mandibular motion can be calculated from two distinct positions of the mandible; however, as these positions come closer together, calculation errors increase. This study investigated the effects of errors in the calculated helical axis on simulated mandibular motion by the measurement of changes in occlusal contacts. A standard helical axis was calculated from a simulated lateral movement. A series of digital interocclusal records from centric to a 5 degree mandibular rotation about the standard helical axis was created. Digital dental cast models were aligned to the interocclusal records. Helical axis parameters and occlusal contacts calculated with the use of the aligned digital models were compared with those of the standard. Helical axes calculated from mandibular positions separated by 1.5 degrees to 5.0 degrees yielded equivalent occlusal contacts. Qualitatively, contacts for helical axes calculated from jaw rotations of 0.7 degrees or larger were nearly identical to those of the standard.

Computer Simulation↗

PubMed1990

Affinity purification of a major Alternaria allergen using a monoclonal antibody.

An extract of Alternaria (ALT) was passed through an affinity column containing a monoclonal antibody directed to ALT. After washing the column, a single glycoprotein was eluted using 0.1 M glycine (pH 3.0). This glycoprotein accounted for 13% of the dry weight of our ALT preparation and had a carbohydrate to protein ratio of 0.35 as compared with 3.2 for the whole ALT extract. Its molecular weight was 70 kD by SDS-PAGE and isoelectric point was 3.5 by IEF. Though individual sensitivities varied, 14/16 patients skin reactive to ALT were also reactive to this glycoprotein. Quantitative skin tests of extracts adjusted to the same dry weight per volume showed that it required about a four times greater concentration of the purified glycoprotein to give a wheal size equal to whole Alternaria. The ability to purify large amounts of this allergen with affinity chromatography should make its complete characterization possible.

Adolescent↗

PubMed1989

Human fetal spinal cord xenografts survive in the eye of athymic nude rat hosts.

Human fetal spinal cord tissue was recovered from elective abortions and grafted to the anterior chamber of the eye of adult athymic nude rats. The transplants slowly became vascularized from the host iris during the first months. There was a clear cut stage-dependent survival and growth along a more "human" time-table. Fetal spinal cord tissue from embryos younger than gestational week 8 showed a much better survival and growth than tissue from older stages. Using laminin immunohistochemistry blood vessels could be visualized in the grafts. The pattern of vascularization was, however, clearly abnormal; there were fewer vessels which had abnormally thick walls as compared to those in the normal spinal cord. Similar to rat spinal cord allografts the human spinal cord xenografts displayed a relative gliosis and were surrounded by a glial layer visualized with antibodies against glial fibrillary acidic protein. Neurofilament-immunoreactive fibres were found inside the glial layer. A variety of neurons were found including large polygonal motoneuron-shaped cells, albeit with CGRP and AChE negative cell bodies. Both Substance P and enkephalin-immunoreactive cells and fibres were found. It is concluded that xenografted fetal human spinal cord survives, grows and may provide a useful model for experimental studies of human spinal cord development and connectivity.

Animals↗