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Biomedical subjects

M D Olson

Publications and source records attributed to M D Olson.

28 records · Page 2Linked to original sources
PubMed1981

The case for self-insurance.

Faced with escalating costs for primary professional liability insurance, many hospitals are considering self-insuring at least part of their professional liability risk. Self-insurance offers advantages over commercial insurance in several areas. The most important corollary of self-insurance from the perspective of the board is the need for more intimate involvement in the quality of medical practice in the institution.

Hospitals↗
PubMed1979

Scanning electron microscopy of developing photoreceptors in the chick retina.

Photoreceptor morphogenesis in the sensory retina of chicks of 2 to 20 days incubation age was studied by scanning electron microscopy (SEM) and correlative transmission electron microscopy (TEM). At 9.5 days spherical inner segments extend into the subretinal space (optic ventricle). They are randomly arranged with chiefly smooth surfaces and contain centrioles, polyribosomes and microtubules. Microvilli project primarily from Müller cells. By the twelfth day immature ellipsoid and myoid regions have formed. Microvilli are abundant on the lateral surfaces of inner segments and extend over the entire spherical surface by the fifteenth day. Occasional cilia with surrounding depressions at their bases were also observed. Inner segments are more symmetrically arranged due to close proximity of photoreceptor cells. Inner segments elongate during the sixteenth day; many display a transitional ovoid form. Microvilli become less numerous but some persist as calycal processes. By the eighteenth day, conical shaped outer segments appear. Thereafter, all photoreceptor cells are comparable to those in the mature retina. Abundant microvilli on the external surface of the sensory retina suggest a supportive role in supplying adequate nutrition to the sensory retina during morphogenesis. The establishment and continual development of the ellipsoid and myoid appear to be primarily responsible for the elongation of photoreceptor cells.

Animals↗
PubMed1979

Morphogenesis of rod cells in the retina of the albino rat: a scanning electron microscopic study.

This study presents scanning electron microscopic (SEM) observations of topographical changes that occur during morphogenesis of rod cells in the albino rat. Correlative transmission electron microscopy (TEM) was also utilized. Albino rats ranging in age from birth to three weeks were used for the study. Tissues were prepared by conventional methods for SEM and TEM. At birth, numerous irregularly arranged inner segments extend from the external surface of the sensory retina. They are spherical, smooth surfaced and possess a randomly oriented cilium. The internal morphology of these immature inner segments is comparable to that observed in other vertebrate species. Statistical analysis reveals a rapid increse in the number of rod cells during the first week. This period is characterized by the elongation of inner segments and their associated cilia. Microvilli project from the apices of Müller cells, but not from adjacent inner segments. By day 5, cilia occasionally display small bulbous outer segments. They are more numerous by day 8 and are usually eccentrically positioned at the tips of cilia. By day 11, outer segments are abundant and frequently obscure from view the underlying inner segments and associated cilia. Elongated cylindrical outer segments are present within the posterior retina at the end of the second week. However, rod cell morphogenesis lags in the peripheral retina. Topographical variations between developing photoreceptor cells in mammalian and non-mammalian retinas are discussed.

Aging↗
PubMed1979

Development of Bruch's membrane in the chick: an electron microscopic study.

The development of fibrous connective tissue in Bruch's membrane within the choroid of chronologically staged chick embryos was observed by means of transmission electron microscopy. The appearance of these connective tissue elements follows an orderly developmental sequence. The first component of Bruch's membrane to appear is a continuous basal lamina at the basal surface of the presumptive retinal pigment epithelium (RPE) at 21/2 days. Microfibrils and associated amorphous material are present in the adjacent connective tissue space. A discontinuous inner collagenous layer is observed at the basal aspect of the RPE during the fourth day. A definitive elastic layer is present during the ninth day and becomes more apparent following subsequent stages of development. An outer collagenous layer begins development during the tenth and twelfth days. Collagenous fibrils average 37 nm in diameter and display axial periodicity measuring 46 nm between major periods. These measurements increase with age as do the number of collagenous fibrils. Only isolated patches of basal lamina are observed in association with the choriocapillary endothelium by the twentieth day.

Animals↗
PubMed1979

Correlated scanning and transmission electron microscopy of developing lens vesicle in the chick.

Cells within the lens placode undergo transient surface modifications during the course of invagination. At stage 13, cellular apices bulge outward and display decreased surface diameters when compared to adjacent surface ectoderm. The lens vesicle is well invaginated by stage 14. An area of modified cells can be recognized ventral to the lens vesicle aperture. These cells present a smaller surface area and increased pleomorphism. Normal surface ectoderm extends to the dorsal and lateral edges of the aperture. The apical surfaces of cells which line the lumen of the lens vesicle display a complex topography such that individual cell boundaries are not easily distinguished. At stage 17, cellular processes which partially occlude the closing aperture of the lens vesicle may assist in reestablishing ectoderm over the newly formed lens. Preliminary results of cytochalasin B exposure on the invaginating lens vesicle suggest that the contractile action of microfilaments influences the complex cellular topography.

Animals↗
PubMed1978

Be ready for the out-of-control ED patient.

Increased use of emergency departments has opened up physicians and hospitals to a variety of unusual liability charges, especially with regard to the violent or destructive patient. In addition, the expansion of the legal concept of "foreseeability" has made this litigation more difficult to defend in court. Therefore, it is vital for an emergency department to have a sound, working screening system and accurate method of documenting patient conduct.

Emergency Service, Hospital↗
PubMed1976

Apical bearing and success with the Bausch and Lomb Soflens (polymacon) contact lens.

Thirty-three patients (63 eyes) were fitted with Bausch and Lomb soflens (polymacon) contact lenses. The initial lenses were selected with the mean posterior apical radius 0.45 mm flatter than the flat keratometer reading of the cornea (S.D. = +/-0.31 MM). Forty-eight eyes (76%) were successfully fitted and 15 eyes (25%) were unsuccessfully fitted. Among the successfully fitted eyes, 31 were fitted with the initial lens, 12 required steeper lenses, and 5 required flatter lenses. The final successfully fitted lenses were on the average 0.40 mm flatter (S.D. = +/-0.32 mm) than the flat keratometer reading of the cornea. The unsuccessfully fitted lenses were not significantly different than the successfully fitted lenses, being 0.47 mm flatter (S.D. = +/-O.32 mm) than the flat keratometer reading of the cornea. Although the central lens-cornea relationship is helpful in fitting the Soflens, the number of successful results are increased significantly by changing to a lens with different parameters when lens performance and patient response are not optimal.

Adolescent↗