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Biomedical subjects

A V Loud

Publications and source records attributed to A V Loud.

44 records · Page 3Linked to original sources
PubMed1968

A quantitative stereological description of the ultrastructure of normal rat liver parenchymal cells.

The principles of stereology have been applied to a morphometric analysis of parenchymal cells from the peripheral, midzonal, and central regions of normal rat liver lobules. The fractional volumes of cytoplasm occupied by mitochondria, peroxisomes, lysosomes, lipid, and glycogen have been determined. The surface densities of smooth- and rough-surfaced endoplasmic reticulum and of mitochondrial envelope and cristae have also been measured. The average number and dimensions of mitochondria and peroxisomes have been evaluated. By the use of an independent measurement of the average cytoplasmic volume, these data have been expressed as the actual volumes, areas, and numbers per cell in the different parts of the hepatic lobule. Similarly, the volumes of the envelope, cristae, and matrix compartments and the area of cristae membranes have been calculated for the average-sized mitochondrion in each lobular zone. Structural homogeneity is found in over 80% of normal rat liver parenchymal cells, with most of the significant differences being confined to those cells immediately surrounding the central veins.

Animals↗
PubMed1968

A quantitative description of cortisone-induced alterations in the ultrastructure of rat liver parenchmal cells.

A stereological comparison of the hepatic parenchymal cells from 125-g male rats given a daily injection for 6 days of either 5 mg of cortisone acetate or saline (controls) was carried out with both light and electron microscopy. Cortisone treatment results in an increase in average parenchymal cell cytoplasmic volume from 5100 to 5800 micro(3) and a decrease in average nuclear diameter from 7.1 to 6.5 micro. The volume of the average mitochondrion is increased fourfold in midzonal and peripheral regions of hepatic lobules, and there is a decrease in the number of mitochondria per cell such that the total mitochondrial volume per cell remains approximately unchanged. The numbers of peroxisomes are reduced, while the numbers of lysosomes and lipid droplets are increased in all parts of the lobules. The average volume of glycogen is doubled in all cells. The areas of membranes of the smooth- and rough-surfaced endoplasmic reticulum are decreased to one-half and two-thirds of their control values, respectively. The effects of cortisone on these various structural elements is discussed with respect to steroid-related alterations in biochemical processes.

Animals↗
PubMed1968

Cortisone-induced alterations in mitochondrial function and structure.

The effects of cortisone treatment on oxygen consumption, oxidative phosphorylation, and fine structure of rat liver mitochondria have been studied. Male rats weighing 125 g were treated for 6 days with 5 mg of cortisone acetate or isotonic saline. On the 7th day, sections of liver were excised and processed for light and electron microscopy. Mitochondrial respiration and oxidative phosphorylation were studied with mitochondria isolated from these livers. Cortisone treatment is responsible for a 14-40% decrease in the amount of oxygen consumed per mg of mitochondrial protein when succinate, alpha-ketoglutarate, or beta-hydroxybutyrate are used as substrates, or with ascorbate and N,N,N(1),N(1)-tetramethyl p-phenylenediamine as electron donors. In addition, oxidative phosphorylation is uncoupled with a lowering of the P:O ratios. Randomly selected liver cells have been analyzed by quantitative morphometric techniques. The average mitochondrial volume is increased fourfold in the peripheral and midzonal regions with a commensurate decrease in the number of mitochondria per cell. These alterations are present throughout the hepatic lobule, but are most marked in midzonal cells. The total mitochondrial volume per cell and the per cent of the total cytoplasmic volume occupied by mitochondria remains relatively unaltered, as does the total amount of cristae surface per cell. While the mitochondria are enlarged, they are not "swollen." The relationships between the steroid hormone treatment and the alterations in mitochondrial function and structure are discussed.

Animals↗
PubMedDate not supplied

Fetal absorption of 3H-leucine injected into the amniotic sacs of pregnants rats.

When injected into the amniotic sacs of fetal rats in late pregnancy, 3H-leucine is rapidly absorbed and incorporated into fetal proteins as determined by liquid scintillation spectrometry. Peak values in the fetal liver and pancreas occur around four hours after injection. Approximately 21% of the radioisotope is retained in the injected fetus at 24 hours. The remainder escapes into the maternal circulation and accounts for a gradual increase in levels in noninjected fetuses from the same litter and for persistently high counts found in maternal serum as late as 24 hours after the injection. Specific activity of the radioisotope in fetal tissues is considerably higher (100- to 200-fold) when 3H-leucine is injected inth the amniotic sac rather than intravenously into the mother. The possible treatment of various fetal disorders by means of intra-amniotic injections is discussed.

Absorption↗