Biomedical subjects

D L Maxwell

Publications and source records attributed to D L Maxwell.

39 records · Page 3Linked to original sources

PubMed1978

A radiographic study of tongue posture at rest and during the phonation of /s/ in class III malocclusion.

In this investigation a group of individuals with Angle Class III malocclusions were studied radiographically to determine their tongue posture at rest and during phonation of /s/. Their speech and hearing was also evaluated. All of the subjects had normal hearing, while eleven of the twelve in the group showed some degree of sibilant distortion. At rest, these Class III subjects demonstrated a tongue posture that was lower than normal and more retruded. During the phonation of /s/ these individuals also demonstrated retrusion of the tongue in an apparent attempt to achieve a normal relationship of the tongue tip to the maxillary anterior teeth, an increased amount of mandibular depression, and a greater than normal distance between the tongue tip and the mandibular anterior teeth. Despite the compensatory movements exhibited by these individuals with Class III malocclusions, normal /s/ production was found in only one of the twelve subjects studied. This is in contrast to the successful compensations that result in normal /s/ production seen in a great number of individuals with a Class III, Division 1 malocclusion, as demonstrated by Subtelny, Mestre and Subtelny.

Adolescent↗

PubMedDate not supplied

Subcellular distribution and immunocytochemical localization of Na,K-ATPase subunit isoforms in human skeletal muscle.

The expression of Na,K-ATPase isoforms was investigated in human skeletal muscle membranes isolated by subcellular fractionation. The alpha 1, alpha 2, alpha 3 and beta 1 subunits were detectable in membranes prepared from the human soleus muscle. The alpha 1 subunit was largely detected in a fraction enriched with plasma membranes (PM), its abundance in an intracellular membrane fraction (IM) accounted for only 4% of that in the PM fraction. No alpha 1 subunits were detected in membranes of sarcoplasmic reticulum (SR) origin. The PM and IM fractions were enriched with alpha 2 subunits which were less abundant in the SR-enriched fraction. The abundance of alpha 2 molecules within the IM fraction was about 75% of that in the PM fraction when the total protein content for the two fractions was taken into account. Immunocytochemical studies confirmed the localization of the alpha 1 subunit to the muscle cell surface. The alpha 2 subunit was also found to be present in the cell surface but the observation that alpha 2 immunofluorescence was diffusely dispersed throughout the muscle fibre indicated that it was also present intracellularly, consistent with its biochemical localization in the PM and IM membrane fractions. The alpha 3 subunit was detected largely in the PM fraction but the lack of good antibodies to this isoform precluded an analysis of its immunocytochemical localization. The beta 1 subunit was enriched in the PM fraction but was also detected to a modest extent in the IM.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗

PubMedDate not supplied

Positive end-expiratory pressure increases pulmonary clearance of inhaled 99mTc-DTPA in nonsmokers but not in healthy smokers.

Positive end-expiratory pressure (PEEP) is widely used in the treatment of severe pulmonary oedema, although its effects on the clearance of water and small solutes from alveolus to blood are not well characterized. We studied the effect of the application of 10 cmH2O of PEEP on the flux of inhaled 99mTc-diethylene-triamine-penta-acetic acid (DTPA) from lung to blood in six healthy smoking and six nonsmoking subjects. The rate of flux was corrected for possible changes in pulmonary blood volume during PEEP by use of an intravenous injection of 99mTc-DTPA. The baseline clearance rate (K, % X min-1) for nonsmokers was 1.48 +/- 0.12 (mean +/- SE) and increased to 2.40 +/- 0.29 during PEEP (p less than 0.05). In contrast, the mean clearance rate for smokers was 3.26 +/- 0.82 at baseline and 3.03 +/- 0.82 during PEEP (p = NS). The application of positive end-expiratory pressure appears to increase alveolar solute flux in nonsmokers but not in smokers, suggesting that the pathway for solute clearance in smokers is governed by different rate-limiting steps to those of nonsmokers.

Administration, Inhalation↗