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Biomedical subjects

R Vracko

Publications and source records attributed to R Vracko.

At least 37 records · Page 2Linked to original sources
PubMed1979

Basal lamina of alveolar epithelium and capillaries: quantitative changes with aging and in diabetes mellitus.

Epithelial and capillary basal laminae (BL) of alveoli are significantly thicker in diabetics than they are in age-matched control subjects. The degree of thickening does not correlate significantly with patient age or with known duration of diabetes. The thickness of both types of BL in the lungs correlates significantly with thickness of BL in renal tubules and muscle capillaries. However, in muscle capillaries and in renal tubules, the BL deposits are 5 to 10 times greater than they are in the lungs. The effects of BL changes on pulmonary function remain to be explored.

Adolescent↗
PubMed1975

Problems in the development of a clinically oriented program in electron microscopy.

The educational, organizational, and fiscal aspects of electron microscopy are discussed.. with emphais on the desirability of making electron microscopy an integral part of the formal training of residents in pathology and of the overall educational program of the medical staff. The rapidity of feedback of information from the pathologist to the clinician is stressed. The number of specimens processed and the variety of tissues submitted for electron microscopy can be regulated by the pathologist but should reflect the particular strength of the hospital or its department of pathology. The organization of the electron microscopy facility, its funding, and sharing of the electron microscopy program in the local community of clinical scientists are discussed

Biopsy↗
PubMed1975

Education and training in electron microscopy.

There is currently a need for diagnostic electron microscopy in both autopsy and surgical pathology. As more information emerges from the research laboratories, applied electron microscopy will grow in depth, and all large medical centers will need the expertise provided by a diagnostic electron microscopy laboratory. Many physicians other than electron microscopists find it essential to have an understanding of the contributions and limitations of electron microscopy. Education and training programs therefore must encompass not only paramedical personnel who prepare the electron micrographs and pathologists who are thoroughly trained in interpret the electron micrographs, but also other physicians and scientists who utilize the information obtained therefrom. Medical students should obtain sufficient background in normal and abnormal ultrastructure to enable them to interpret the medical literature, and the means to obtain this background should be available within the medical school curriculum. Some medical students will also desire more thorough training obtained by elective courses in electron microscopy. Pathology residents should obtain sufficient expertise during their residency to enable them to utilize the information produced by the electron microscopy laboratory. Certain pathology residents and some pathologists in practice prefer fellowships for more specialized training in electron microscopy. Four representative training programs in electron microscopy from Veterans Administration hospitals have been selected for presentation. Each emphasizes a different approach and different objectives.

District of Columbia↗
PubMed1975

Restricted replicative life-span of diabetic fibroblasts in vitro: its relation to microangiopathy.

The finding that diabetic microangiopathy is caused by accumulation of multiple layers of basal lamina and experiments in which similar basal lamina layering is produced when new cell generations repopulate preexisting basal lamina scaffolding (from which previous cell generations have shed) indicate, that the rates of cell death and cell replenishment are accelerated in diabetics. Because the lesions are focal and regional and develop at different ages and in different time sequences, we have proposed that the accelerated cell turnover is probably caused by increased vulnerability of diabetic cells to injury which in turn may represent the expression of a genetically transmitted defect. To test whether this aberration can be detected in vitro, we examined the replicative life-span of skin fibroblasts from three nondiabetics, three age- and sex-matched diabetics and one individual with acquired hyperglycemia due to pancreatitis. Cells of diabetics exhibited about half the number of population doublings as cells from nondiabetics (0.01 less than P less than 0.025). Cells of the individual with pancreatitis generated a normal number of cell doublings. The interpretation that fits best with all data is that decreased replicative life span of diabetic fibroblasts in vitro is also an expression of increased susceptibility of diabetics' cells to injury and dying.

Adult↗
PubMed1975

Malakoplakia. Defect in digestion of phagocytized material due to impaired vacuolar acidification?

On the basis of light and electron microscopical findings in a case of malakoplakia of urinary bladder, (1) we concur with others that malakoplakia is a hyperplastic accumulation of histiocytes, and that the formation of Michaelis-Gutmann bodies is associated with incomplete digestion of phagocytized cell debris; (2) we hypothesize that digestion within phagolysosomes is impaired because of deficient acidification; and (3) we suggest that the defect in acidification in some cases may be related to treatment with drugs that affect the mechanism of phagocytic vacuolar acidification.

Carbonic Anhydrase Inhibitors↗
PubMed1974

Basal lamina scaffold-anatomy and significance for maintenance of orderly tissue structure.

The basal lamina is an extracellular scaffold positioned between parenchymal cells and connective tissue. Parenchymal cells attach to one of its surfaces and the other is anchored to connective tissue. By its presence it defines the spatial relationships among similar and dissimilar types of cells and between these cells and the space occupied by connective and supportive tissues. Replenishment of cells which have died during normal functioning or have become damaged in course of injury occurs with new cells in an orderly way along the framework of the basal lamina scaffold. This process appears to be aided by the polarity of the basal lamina and by an apparent specificity for cell types, and it enables multicellular organisms to reconstitute histologic structures of most tissues and organs to what they were prior to loss of cells. If the basal lamina is destroyed, the healing in most tissues results in formation of scar and loss of function. The properties of the basal lamina concerned with maintenance of histologic order in organs and tissues offer new ways to interpret the pathogenesis of several common disorders, including emphysema, scars, adhesions, cirrhosis of liver and excessive accumulation of basal lamina material as, for example, it occurs in patients with diabetes mellitus.

Animals↗
PubMed1972

Basal lamina: the scaffold for orderly cell replacement. Observations on regeneration of injured skeletal muscle fibers and capillaries.

To explore in detail the relationships between basal lamina (BL) and regenerating cells, we have studied the reconstruction of skeletal muscle fibers and their associated capillaries in portions of rat and rabbit skeletal muscles after injury with either freezing, ischemia, or in situ autografting. Each type of injury produces complete necrosis of cells. The BL, however, remains intact in the area of injury and maintains a "map" of the outline of the spatial relationships between muscle fibers and capillaries. Repopulation of the defect with new cells occurs primarily along the old BL. The spatial relationship between cells, as it existed before injury, is thus reestablished. This process appears to be aided by the ability of each category of regenerating cells to grow along the cell-supporting surface of its own BL. The regenerating cells of muscle fibers and capillaries frequently form a new layer of BL. It is of the usual thickness and is deposited primarily along the outer surfaces of plasma membranes in locations in which the new cells are separated from the old BL. Where an old layer of BL is present overlying a newly formed layer, the old layer may be retained or it may be removed. Removal of redundant BL is probably mediated by interstitial cells which embrace the outside surfaces of BL of regenerated skeletal muscle fibers and capillaries.

Animals↗