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Biomedical subjects

F Miller

Publications and source records attributed to F Miller.

At least 253 records · Page 14Linked to original sources
PubMed1974

Electron microscope study of mitochondrial 60S and cytoplasmic 80S ribosomes from Locusta migratoria.

Purified mitochondrial ribosomes (60S) have been isolated from locust flight muscle. Purification could be achieved after lysis of mitochondria in 0.055 M MgCl(2). Mitochondrial 60S and cytoplasmic 80S ribosomes were investigated by electron microscopy in tissue sections, in sections of pellets of isolated ribosomes, and by negative staining of ribosomal suspensions. In negatively stained preparations, mitochondrial ribosomes show dimensions of approximately 270 x 210 x 215 A; cytoplasmic ribosomes measure approximately 295 x 245 x 255 A. From these values a volume ratio of mitochondrial to cytoplasmic ribosomes of 1: 1.5 was estimated. Despite their different sedimentation constants, mitochondrial ribosomes after negative staining show a morphology similar to that of cytoplasmic ribosomes. Both types of particles show bipartite profiles which are interpreted as "frontal views" and "lateral views." In contrast to measurements on negatively stained particles, the diameter of mitochondrial ribosomes in tissue sections is approximately 130 A, while the diameter of cytoplasmic ribosomes is approximately 180-200 A. These data suggest a volume ratio of mitochondrial to cytoplasmic ribosomes of 1:3. Subunits of mitochondrial ribosomes (40S and 25S) were obtained by incubation under dissociating conditions before fixation in glutaraldehyde. After negative staining, mitochondrial large (40S) subunits show rounded profiles with a shallow groove on a flattened side of the profile. Mitochondrial small subunits (25S) display elongated, triangular profiles.

Animals↗
PubMed1974

Serum ferritin in children with thalassaemia regularly transfused.

A controlled trial of continuous chelation therapy in regularly transfused children with homozygous beta-thalassaemia has been in progress at the Hospital for Sick Children since April 1966. In the sixth and seventh years of the trial the effect of this treatment on iron overload has been assessed by estimating serum ferritin levels and liver iron concentrations in both chelator-treated and control groups. When compared with non-chelated controls, results of both these estimations were invariably lower in the chelated group. However, all the results in both groups were very high, and fell within the ranges observed in untreated idiopathic haemochromatosis. A close correlation was found between serum ferritin levels and liver iron concentrations in these children, indicating that serum ferritin is a valuable alternative to liver iron concentration in the assessment of visceral iron overload, even when massive tissue siderosis is present.

Blood Transfusion↗
PubMed1972

The localization of endogenous peroxidase in the lacrimal gland of the rat during postnatal development. Electron microscope cytochemical and biochemical studies.

The distribution of endogenous peroxidase activity in the lacrimal gland of the rat during postnatal development was investigated by electron microscope cytochemistry Peroxidase activity is first found 6 hr after birth in only a few acinar cells At this stage, reaction product fills only localized segments of the scant rough endoplasmic reticulum and of the perinuclear cisternae. Peroxidase activity thus develops asynchronously in a given cell as well as in the secretory cell population as a whole 2 days after birth, all cisternae of the rough endoplasmic reticulum of a peroxidase-positive cell contain reaction product, but the majority of the acinar cells is still negative During the next days, the number of peroxidase-positive cells and the amount of the rough endoplasmic reticulum increase rapidly. By 15 days postparturition, all secretory cells are peroxidase-positive. Reaction product is then found in all cisternae of the rough endoplasmic reticulum including the perinuclear cisternae, in smooth surface vesicles located mainly between the rough endoplasmic reticulum and the Golgi stacks, in condensing vacuoles, and in all secretory granules The Golgi cisternae rarely contain reaction product In total homogenates and in fractions of glandular tissue of adult rats, peroxidatic and catalatic activities are demonstrable. The microsomal fractions and the postmicrosomal supernatants were used to separate peroxidase from catalase by precipitation with ammonium sulfate, and the following parameters were determined: substrate (H(2)O(2-)) optimum ( approximately 2.0 x 10(-4)M), pH-optimum (pH 6 5), temperature-optimum (42 degrees C), and the absorption maximum (415 nm before and 425 nm after addition of H(2)O(2)) The same parameters were obtained from lacrimal fluid peroxidase. Both peroxidase from lacrimal gland and that from lacrimal fluid are almost completely inhibited by 10(-3)M aminotriazole and are possibly identical enzymes. Peroxidase is secreted into lacrimal fluid, which does not contain catalase.

Animals↗