Biomedical subjects
Publications and source records attributed to P Sampson.
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The purpose of this study was to evaluate the long-term stability of orthodontically induced changes in maxillary and mandibular arch form. Dental casts were evaluated before treatment, after treatment, and a minimum of 10 years after retention for 45 patients with Class I and 42 Class II, Division 1 malocclusions who received four first premolar extraction treatment. Computer generated arch forms were used to assess changes in arch shape over time. Buccal cusp tips of first molars, premolars, and canines plus mesial, distal, and central incisal aspects of incisors were marked, photocopied, and digitized in a standardized manner. An algorithm was used to fit conic sections to the digitized points. The shape of the fitted conics at each time period was described by calculating the parameter eccentricity; a small value represented a more rounded shape and a larger value represented a more tapered shape. Findings demonstrated a rounding of arch form during treatment followed by a change to more tapered. Arch form tended to return toward the pretreatment shape after retention. The greater the treatment change, the greater the tendency for postretention change. However, individual variation was considerable. The patient's pretreatment arch form appeared to be the best guide to future arch form stability, but minimizing treatment change was no guarantee of postretention stability.
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In exploring further the structural features that influence the relative efficacy of analogues of aminoglutethimide [1, 3-(4-aminophenyl)-3-ethylpiperidine-2,6-dione] as inhibitors of the cholesterol side-chain cleavage enzyme system desmolase and the estrogen forming system aromatase, analogues have been synthesized in which the aminophenyl substituent is replaced by pyridyl or substituted pyridyl. The 4-pyridyl analogue 5 [3-ethyl-3-(4-pyridyl)-piperidine-2,6-dione] is a strong competitive inhibitor of aromatase (Ki = 1.1 microM; value for 1, 0.60 microM), which exhibits a type II difference spectrum (Ks = 0.28 microM; value for 1, 0.13 microM) but is noninhibitory toward desmolase. The 2- and 3-pyridyl analogues (3 and 4) inhibit neither enzyme system. 1-Amino-3-ethyl-3-phenylpiperidine-2,6-dione (2) is a strong and selective inhibitor of desmolase but the 4-pyridyl analogue 10 [1-amino-3-ethyl-3-(4-pyridyl)-piperidine-2,6-dione] is a weak inhibitor of desmolase and aromatase. Analogues of 5 having a less basic aromatic substituent, namely, the N-oxide 11 and the 2,3,5,6-tetrafluoro derivative 13, were also prepared. The latter is a weak inhibitor of aromatase and the former inhibits neither enzyme system.
Although polyploid nuclei have long been known to be present in many adult human tissues, the ploidy of smooth muscle cells in human artery wall has never been determined. We measured DNA content in individual smooth muscle cell nuclei of artery wall specimens by two means: Feulgen microdensitometry and flow microfluorimetry. A significant percentage of nuclei were polyploid; most of these were tetraploid, although higher levels were also found. The frequency of polyploidy varied with age from less than 1% at birth to a mean of 7% in adult aortic, carotid, and iliac vessels. Atherosclerotic plaques had a lower tetraploid content than the underlying media, whereas normal intima was similar to the corresponding media. The increase in frequency of hyperploid smooth muscle cell nuclei correlates with the normal growth, development, and aging of human artery wall. We suggest that the regular existence of a subset of polyploid smooth muscle cells may indicate an important functional role for this phenotype.
We have identified the ultrastructural localization of anionic sites on the luminal surface of the pulmonary microvascular endothelium by perfusing isolated rat lungs with polycationized ferritin (CF). The ligand decorated preferentially the luminal plasmalemma, coated pits, intercellular clefts, and about half of the plasmalemmal vesicles open to the lumen. Decoration of the plasmalemma was not uniform particularly in the nonvesiculated regions of the endothelium. Perfusion of the lung with high salt solution completely abolished binding of CF to the plasmalemma, coated pits, and intercellular clefts but did not significantly decrease binding of CF to the diaphragm of the luminal plasmalemmal vesicles. This indicates the presence of highly charged anionic sites on these regions of the endothelium. CF was taken up by vesicles and discharged on the capillary membrane. Perfusion of the lungs at 4 degrees C completely abolished transport of CF across the endothelium but did not modify the pattern of binding to the luminal endothelial surface. These findings are regarded as evidence for a functional subspecialization of plasmalemmal vesicles in the pulmonary microvascular endothelium.
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The glycosaminoglycans produced by a mixed cell line of normal adult rat lung and an endothelial clone derived from this line were isolated and examined. Cellulose acetate electrophoresis of media and cells before and after digestion with specific enzymes indicated that all the major glycosaminoglycans except keratan sulfate were synthesized by both cultures. Heparan sulfate and dermatan sulfate were found only in the cell fraction while hyaluronic acid was found in both the medium and the cell fractions. The chondroitin sulfates were isolated from the medium. The endothelial clone produced a 4:1 ratio of glucosamine to galactosamine in the medium from the fifth through thirteenth months of culture. The medium of the mixed cell line initially contained glycosaminoglycans with a glucosamine to galactosamine ratio of 2:1 but after approximately one year of culture, the ratio had changed to 4.6:1 suggesting that the culture contained predominatly endothelial cells.
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Treatment of keratosulfates with alkali leads to the formation of 3,6-anhydroglucosaminyl groups in high yield. A similar reaction takes place with heparin and heparitin sulfate, though to a lesser extent. The anhydrosugar was isolated and compared with synthetic 3,6-anhydroglucosamine. The isolated compounds were identical in ion exchange chromatography in the amino acid analyzer and on Dowex 50 H(+) eluted with dilute HCl. The spectra of the isolated and synthesized anhydrosugar were identical in infrared and nuclear magnetic resonance. Derivatized compounds were identical in gas-liquid chromatography and mass spectroscopy. The peracetylated compound isolated from keratosulfate gave the nuclear magnetic reasonance and fragmentation pattern of the postulated compound. The reaction is expected to be useful in structural studies of hexosamine-containing polymers.