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Biomedical subjects

J L Ackerman

Publications and source records attributed to J L Ackerman.

52 records · Page 3Linked to original sources
PubMed1975

A systematic modification of edgewise therapy.

This article describes a highly systematic modifcation of the edgewise technique that incorporates the principle of light continuous force application. It is a re-evaluation of our earlier article in view of the experience gained in applying this treatment approach in a teaching clinic. The classification of cases according to retraction requirements, the appliance designs, and the use of four basic phases of treatment remains largely the same as previously described. Some of the variations and modifications that have been necessary because of new information and pedogogical considerations are discussed. The treatment of typical orthodontic problems with differing retraction requirements is illustrated.

Humans↗
PubMedDate not supplied

MR imaging of the lung using liquid perfluorocarbons.

Certain perfluorocarbon (PFC) compounds, commonly used as the oxygen transport components of "blood substitutes," may be breathed as neat liquids with survival because of their chemical inertness and their high solubility for oxygen and carbon dioxide. In addition, the paramagnetism of oxygen reduces the fluorine T1 value according to an inverse relationship allowing a potential method of monitoring PO2 gradients in vivo. This article presents the results of magnetic resonance (MR) imaging of the lungs of mice and rats following breathing of four PFC liquids (FC-43, FC-75, PFOB, APF-215). The images presented were obtained at two magnetic field strengths (0.66 and 0.14 T) under conditions of breathing either ambient air or pure oxygen. Spin-lattice relaxation times (T1) for the PFCs are measured both in vitro and in vivo (in the lungs) as a function of the state of oxygenation. A MR image signal strength enhancement of up to 90% is demonstrated in vivo under conditions of pure oxygen breathing.

Animals↗
PubMedDate not supplied

Deconvolution techniques for removing the effects of chemical shift in 19F nuclear magnetic resonance imaging of perfluorocarbon compounds.

Nuclear magnetic resonance (NMR) imaging of perfluorocarbon (PFC) emulsions and neat liquids has shown potential for in vivo oxygen imaging in blood and organ tissue. PFC compounds exhibit complicated NMR spectra caused by chemical shifts and spin-spin couplings which can lead to artifacts and degraded spatial resolution of resulting NMR images. To correct for the chemical shift artifacts, the technique of spectral deconvolution has been applied to NMR imaging of PFC compounds. The temporal filter for this process can be directly applied to raw free induction decay data in projection reconstruction or to spin-echo data in two-dimensional Fourier transform imaging techniques. The effect of chemical shift artifacts was demonstrated through the NMR imaging of two PFC compounds (F-tributylamine and F-decalin) in phantoms. Methods are presented and demonstrated which allow the chemical shift artifacts to be removed and true images of the spatial distribution of the PFC's to be recovered.

Blood Substitutes↗
PubMedDate not supplied

Oligodontia: a study of its prevalence and variation in 4032 children.

The frequency of oligodontia in the study group was 4.34 percent; 79.82 percent of those with congenitally missing teeth lacked not more than two teeth. In terms of number of teeth missing, there was no significant difference between the maxilla and mandible. When considering the whole dentition, bilateral agenesis was more common than unilateral agenesis. The findings of this study largely confirm the results of previous studies of oligodontia.

Adolescent↗