PubMed Health⌕ Search

Biomedical subjects

O Johnson

Publications and source records attributed to O Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1977

Effects of concurrent verbal and musical tasks on a unimanual skill.

Subjects balanced a dowel rod on the right or left index finger while speaking, while remaining silent, and while humming a melody. In males balancing times for the right hand decreased with concurrent verbalization. Verbalization had no effect on left hand performance in males, nor on either hand in females. Concurrent humming had no effect on performance of males or females. Poorer right hand performance by males when verbalizing is attributed to interference with right-sided motor control by the left hemisphere due to verbal activity programmed by the same hemisphere. Unimpaired right hand performance in verbalizing females suggests that the language function is less clearly lateralized in females than in males. The possibility that music may be shared by both hemispheres is discussed.

Adult↗
PubMed1976

Metabolism of liver triacylglycerols in rats tube-fed a threonine-devoid diet.

Rats tube-fed a diet devoid of threonine accumulated triacylglycerols in their livers, starting on the third day of the diet. The fatty acid composition of the accumulated lipid and the contribution of novo synthesized fatty acids to the lipid accumulation, as determined with tritiated water as a radioactive precursor for fatty acid synthesis, suggested that an increased hepatic de novo synthesis of fatty acids is not a major factor for the development of this liver lipid accumulation. The metabolism of intravenous injected 3H-oleic acid, the Triton-induced hyperlipemia and the activity of lipoprotein lipase in adipose tissue was also studied. None of these studies revealed any significant difference between the threonine-deficient and control rats. It is concluded that the hepatic triacylglycerol accumulation in the threonine-deficient rats does not result from any gross abnormality in the rate of liver triacylglycerol formation or secretion to the plasma. It is suggested that a possible causative mechanism is a derangement in the metabolism of the storage pool of liver triacylglycerols.

Adipose Tissue↗
PubMed1975

Effect of ethanol on utilization of plasma free fatty acids for liver triacylglycerol synthesis and its relation to hepatic triacylglycerol accumulation in rats.

The effect of 3 different single doses of ethanol on the liver triacylglycerol concentration and on the metabolism of intravenously injected 14C-oleic acid in fasted rats was studied. All 3 doses (2, 3.75, and 6 g ethanol/kg body wt) caused a rapid increase in the liver triacylglycerol concentration during the first 5-6 hr after the ethanol was given. Until the plasma ethanol concentration had fallen to low values, the high liver triacylglycerol levels were raised and were independent of the ethanol dose given. The incorporation of radioactivity from intravenously injected 14C-oleic acid into liver triacylglycerols was increased over control values to the same extent in all rats given ethanol as long as the plasma ethanol concentration was above a low level. High rates of ethanol oxidation and increased utilization of plasma free fatty acids for liver triacylglycerol synthesis were closely correlated with the development and maintenance of the ethanol induced liver triacylglycerol accumulation.

Animals↗
PubMed1975

Effect of ethanol on the activity of lipoprotein lipase in adipose tissue of male and female rats.

The effect of a single large dose of ethanol on the activity of lipoprotein lipase in adipose tissue of previously fasted male and female rats was followed over a 16-hour period. Feeding of ethanol caused an increase in the plasma triacylglycerol concentration in both male and female rats. This has previously been attributed to an increased secretion of triacylglycerols from the liver into the plasma. The present results show that there is probably not any significant increase in the uptake of triacylglycerols in adipose tissue after ethanol feeding in male and female rats, since there was no major increase in the activity of lipoprotein lipase in adipose tissue. This may be a prerequisite for the ethanol-induced increase in the plasma triacylglycerol concentration and shows the unphysiological nature of ethanol as a source of energy.

Adipose Tissue↗
PubMedDate not supplied

Three-dimensional reconstruction and motion analysis of living, crawling cells.

Cell behavior is three-dimensional (3-D), even when it takes place on a flat surface. Migrating cells form pseudopods on and off the substratum, and the cell body undergoes height changes associated with a 1 min behavior cycle. Inside the cell, the nucleus has a 3-D migratory cycle, and vesicles move up and down in the z-axis as a cell locomotes. For these reasons, the two-dimensional (2-D) analysis of cellular and subcellular behavior is, in many cases, inadequate. We have, therefore, developed 3-D motion analysis systems that reconstruct the cell surface, nucleus, pseudopods, and vesicles of living, crawling cells in 3-D at time intervals as short as 1 s, and compute more than 100 parameters of motility and dynamics morphology at 1-s intervals. We are now in the process of developing a multimode reconstruction system that will allow us to reconstruct and analyze fluorescently tagged molecular complexes within the differential interference contrast-imaged subcellular architecture of a crawling cell. These evolving technologies should find wide application for a host of biomedical problems.

Animals↗