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Biomedical subjects

D Seiden

Publications and source records attributed to D Seiden.

10 recordsLinked to original sources
PubMed1989

Changes in myosin isozyme expression during cardiac hypertrophy in hyperthyroid rabbits.

The myosin isozyme distribution in the left ventricle and in the interventricular septum of rabbits was studied after 3, 7, 11, 14 and 21 days of L-thyroxine (500 micrograms/kg/day) administration. Histochemical procedures were employed to identify V1 and V3 by their Ca2+ ATPase activity and their proportions were quantified through polyacrylamide gel electrophoresis. In the left ventricle, the subepicardium was the first to show the shift from V3 to V1, followed by the subendocardium. The intermediate region became heterogeneous by 11 days and remained so until 21 days. The right subendocardial and the intermediate regions of the interventricular septum were heterogeneous in the normal rabbit and hyperthyroidism resulted in a shift from V3 to V1 in both the right and left subendocardial regions of the septum. Like the left ventricle, the intermediate region of the interventricular septum remained heterogeneous. Localized accumulations of collagen were seen in all regions of the left ventricle and interventricular septum. From these results we conclude that in thyrotoxic myocardial hypertrophy the isozymic shift from V3 to V1 is progressive, region-specific and is directly correlated with the period of hyperthyroidism in the first 2 weeks. Prolonged hyperthyroidism results in localized accumulation of collagen which does not exhibit any regional specificity.

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PubMed1988

Distal axonopathy in streptozotocin diabetes in rats.

We noted the earliest morphological changes in the motor endplates 8 weeks after the induction of streptozotocin diabetes in rats. Morphometric measurements showed reduced axonal areas of the lateral plantar and the sciatic nerves in the diabetic rats 28 but not 2 and 8 weeks after the experiment. These findings suggested distal axonopathy.

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PubMed1988

Oxygen diffusion distance in thyroxine-induced hypertrophic rabbit myocardium.

We studied the oxygen diffusion distance in the rabbit myocardium in untreated animals and in animals treated with thyroxine (T4) for 3 days and 16 days. The subepicardial and subendocardial regions were studied separately. Sixteen days of T4 treatment results in significant cardiac hypertrophy. After 16 days, the percentage of the myocardium occupied by myocytes decreases as the volume of extracellular matrix increases. After 3 days, the number of myocyte mitochondria per unit volume of myocardium increases without an increase in mitochondrial volume. After 16 days the volume density of the myocyte mitochondria increases. Oxygen diffusion distance was determined by measuring the distance between the myocardial capillaries and the cardiomyocyte mitochondria. The deposition of extracellular matrix results in an increase in the distance between the myocardial capillaries and the myocytes. The distribution of the mitochondria within the myocytes remains unchanged resulting in an increased distance between the capillaries and the mitochondria, hence, an increased oxygen diffusion distance. There is some evidence that the mitochondria most distant from the capillaries are the mitochondria in which division is most frequent with T4 stimulation. This may be related to the relative deprivation of oxygen of these mitochondria.

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PubMed1979

Specific granules of the rat atrial muscle cell.

The specific granules found in the atrial cardiac muscle cells of the normal rat were studied. The ultrastructural appearance of these granules demonstrated a fixative-dependent lability. Fixation with cacodylate buffered aldehydes yields three types of granules. However, fixation with phosphate buffered aldehydes or primary fixation with OsO4 yields granules of uniform appearance. The granules are found predominantly in the perinuclear zone; 78% of the granules are within ten linear micrometers of the center of the nucleus. Two independent methods of measurement demonstrate spherical diameters of these granules of 0.30 micron and 0.37 micron respectively. The granules are found in greater concentration at one pole of the nucleus than at the other. On the high density side there are 4.07 granules/micrometers3 which occupy 5.8% of the cytoplasmic volume. On the low density side there are 2.15 granules/micrometers3 which occupy 3.0% of the cytoplasmic volume. The granules at both poles are the same size. Atrial walls were incubated in a modified Tyrode's solution. One hour of incubation caused no change in the atrial granules. Addition of norepinephrine or L-Dopa resulted in the appearance of more granules but the size of the granules remained the same. Incubation with reserpine had no effect upon the atrial granules. Apparently the atrial myocardial cell is stimulated by exogenous catecholamine to synthesize more atrial granules which themselves do not appear to contain catecholamines.

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PubMed1978

Localized fibrous mesothelioma of the pleura.

A benign fibrous pleural mesothelioma was found in a dissecting room cadaver. The gross anatomical relationships to other thoracic structures are fully described. Vascular connections with the thoracic wall, azygos vein and lung were found. The tumor conformed to earlier histologic descriptions of this type of tumor. The potential for vascular shunts within this tumor and the diagnostic problems presented by a tumor of this type are discussed.

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PubMed1976

Quantitative analysis of muscle cell changes in compensatory hypertrophy and work-induced hypertrophy.

The cytological characteristics of two modes of muscle hypertrophy were studied in the extensor digitorum longus muscle of the rat. Comprensatory hypertrophy (CH) was produced by tenotomy of the tibialis anterior muscle and work-induced hypertrophy (WIH) was produced by forced swimming of the animal. While both methods produced an increase in muscle weight and cell size, these two parameters did not correlate. Morphometric analyses of the hypertrophied muscle cells demonstrated that in CH-muscle there was an increase in mitochondrial volume density, a decrease in myofibrillar volume density and no change in sarcotubular or nuclear volume density. WIH-muscle demonstrated an increase in sarcotubular volume density but no change in mitochondrial, myofibrillar or nuclear volume density. It is concluded that in CH-muscle, the cell volume increase is attributable to mitochondrial volume increase and that there is no increase in the contratile myofibrillar component of the cell. WIH-muscle, on the other hand, has a cell volume increase which is attributable to a proportional increase in these organelles.

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