A practical simultaneous alpha beta counter for applied health physics. IDO-17122.
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Radiometry↗
Biomedical subjects
K F Smith
Publications and source records attributed to K F Smith.
Face lift, part I: Extent of undermining of skin flaps.
One theory in cheek-neck lifting is that it is necessary to undermine skin flaps widely to achieve adequate short and long term results. We have proven that extensive undermining allows no more skin to be excised than is permitted by more conservative undermining when snug skin closures are used. Another part of the theory is that a sheet of scar tissue ("favorable fibrosis") forms and that the larger sheet of scar from more extensive undermining maintains the improvement from the lift longer than would a smaller sheet from less undermining. Controlled studies presented here cast doubt on this part of the theory. Many years ago we ran a series on patients in whom one side had essentially twice as much undermining as did the other. Equal amounts of skin were removed on both sides. Short and long term results were essentially the same on the two sides.
Cicatrix↗
Face lift, part 2: Etiology of platysma cording and its relationship to treatment.
Based on examination of many necks and observations at surgery and on cadavers, we believe that "platysma cords"' or cervical folds are normal when the muscles are being contracted. In the aged, they do not disappear when the muscle is relaxed. We believe that they are caused by a stretching and loss of contractility of skin and fat overlying the anterior platysma muscles from aging and from the many contractions of these muscles which selectively stretch the overyling tissues. In addition, we believe that the superficial musculoaponeurotic system (SMAS), which in youth holds the muscle strongly and closely to the confines of the concavity of the neck, stretches so that the muscle webs more easily out of the concavity when contracted and is returned less completely into it upon relaxation. Treatment and prevention should be directed toward tightening the skin and the SMAS and supporting the muscle in its retrodisplaced, more youthful position.
Adolescent↗
Face lift, Part 3: Plication of the superficial musculoaponeurotic system.
It is thought that plicating or folding the superficial musculoaponeurotic system (SMAS) upon itself near the ear with permanent sutures will improve and help maintain the results of cheek-neck lifting of the skin layer alone. Getting proof of this conjecture with controlled studies is difficult in the existing medicolegal climate. However, many years ago, we did carry out a limited study in a few patients in whom plication was performed on one side only. We found that plication does have some relatively long-lasting effects, particularly in improvement of platysma cording and in elevation and deepening of the cervical angle. Plication is not a substitute for adequate skin and/or fat resection. Because the early improvement in cases with platysma cording was so marked in contrast to the unplicated side, we had to limit the series stringently. As time went by, the differences on the two sides lessened.
Face↗
Face lift, Part 4: Use of superficial musculoaponeurotic system suspending sutures.
We describe nonabsorbable sutures running from one or more sites in the superficial musculoaponeurotic system (SMAS), to other sites at a distance, or to fixed sites beyond or deep to SMAS for the purpose of pulling on or suspending the distal selected SMAS sites or changing contours between the suture ends. Our reasons for abandoning some sutures and continuing with others are stated. In face lifting, we still often employ sutures running from the anterior part of the platysma and SMAS back to the sternocleidomastoid fascia. These sutures help prevent platysma "cording" and are useful in the restoration and preservation of a more youthful profile in the neck. Examples and controls are demonstrated. These sutures and the long-term results of their use have never been shown before. Problems encountered in using suspending sutures are described.
Face↗
Face lift, part 5: suspending sutures for platysma cording.
We describe the technical details used in applying nonabsorbable sutures running from the anterior platysma muscles and/or adjacent fascia back to the fascia just in front of or covering the sternocleidomastoid muscles. These sutures usually pass 1.5-2 cm below the angle of the mandible. Anteriorly, they cover or are attached to the platysma muscles at the level of the cervical concavity or angle. The sutures suspend or draw back the superficial musculoaponeurotic system (SMAS) at this level, preventing some of the anterior displacement of the platysma when it is contracted in normal use. We believe that the sutures have relatively long-lasting effects and that they delay the early return of "platysma cording" after cheek-neck lifting. Their application using Reverdin and Keith needles is demonstrated. Differences in technique when submental lipectomy is and is not performed with the lift are shown.
Face↗
Small liver fenestrae may explain the susceptibility of rabbits to atherosclerosis.
Rabbits fed cholesterol rapidly develop high serum cholesterol levels which lead to the development of atherosclerosis. This is related to the retention of cholesterol-rich chylomicron remnants in the circulation. In most animals, such as rats, chylomicron remnants are rapidly removed from the circulation by the liver. The first barrier to this removal is the fenestrated endothelium of liver sinusoids. Measurements made of a large number of sinusoidal fenestrae by scanning electron microscopy have shown the average diameters to be 89 nm in rats and 49 nm in rabbits. We postulate that the small size of endothelial fenestrae in the liver sinusoids of rabbits hinders the egress of chylomicron remnants from the sinusoidal blood, explaining the subsequent development of hypercholesterolemia and atherosclerosis.
Animals↗