Search PubMed⌕ Search

Biomedical subjects

J M Riddle

Publications and source records attributed to J M Riddle.

At least 73 records · Page 4Linked to original sources
PubMed1981

Surface morphology of degenerated porcine bioprosthetic valves four to seven years following implantation.

The surface structure of leaflets from two processed but unimplanted porcine bioprosthetic valves and six degenerated porcine bioprosthetic valves that were surgically removed because of valvular dysfunction after approximately 4 to 7 years implantation were studied with the scanning electron microscope. Variable degrees of endothelial denudation with the resultant exposure of corresponding areas of subendothelial fibers was the typical surface characteristic of the processed but unimplanted porcine valve heterograft. Structural alterations demonstrated on the surface of leaflets from the degenerated porcine bioprosthetic valves included loss of endothelial cells, exposure of large areas of basement membrane material, exposure of wide expanses of subendothelial fibers, fibrin formation, the presence of activated leukocytes, adherent single platelets as well as reversible and irreversible platelet aggregates, and focal accumulations of crystalline deposits. Each of these morphologic features may be a potential contributor to the progressive degradative process.

Animals↗
PubMed1980

Spontaneous degeneration of porcine bioprosthetic valves.

From October, 1971, to October, 1979, 490 patients with 560 porcine bioprosthetic valves were discharged from the hospital. During these 8 years, 23 valves were removed because of failure due to spontaneous degeneration. Bioprosthetic valve survival without degeneration was at 4 years, 98.9% +/- 86 (standard error); at 5 years, 96.4% +/- 1.3; at 6 years, 90.8% +/- 2.4; and at 7 years, 84.2% +/- 3.7. There was no difference in degeneration observed with regard to sex, valve position, or whether the valves were rinsed with antibiotics prior to implantation. There was an increase in degeneration in patients 35 years old and younger compared with those more than 35 years old (p = 0.0001). Valve failure was gradual, and valve changes were noted by echocardiogram and phonocardiogram prior to actual failure. Specific factors leading to degeneration require further investigation.

Adolescent↗
PubMed1980

Surface topography of stenotic aortic valves by scanning electron microscopy.

Surface features of 19 stenotic aortic valves from patients undergoing valve replacement were investigated by scanning electron microscopy. Villi, prominent on five valves, were distributed either singularly or in clusters and differed in shape. Endothelial cells had microvilli and bulbous surface projections. Endothelial disruption with a focal loss of endothelial cells was uniformly observed. Erythrocytes were found scattered over the exposed subendothelial surface or enmeshed within fibrin networks on 11 of the valves. Activated leukocytes were seen on four valves and showed veil-like projections as well as microvilli. Platelets, observed on three valves, displayed pseudopodial formation and hyalomeric spreading, signifying an increased degree of membrane response. Most platelet aggregates were composed entirely of dendritic forms (reversible aggregates), but a few also contained spread forms (irreversible aggreates). Focal deposits of crystalline material, presumably containing calcium, were observed in areas of endocardial disruption.

Aortic Valve↗
PubMed1979

Surface topography and fine structure of the Legionnaires' disease bacterium. A study of six isolates from hospitalized patients.

Six clinical isolates of the Legionnaires' disease bacterium have been isolated from patients in two Michigan hospitals. These organisms were recovered and cultivated in vitro and the strains named by city of recovery and order of isolation Detroit 1 to 4 and Flint 1 and 2. All strains, studied by scanning and transmission electron microscopy preparations from 7-day growth on agar, showed similar characteristics. By scanning electron microscopy the cells appeared bacillary, straight, and slightly curved, and spindle shapes and forms with rounded ends were observed. Detroit 2 and 3 and Flint 1 strains showed cells with ends having reduced diameters, the cells resembling an old-fashioned rolling pin. Cell widths ranged from 0.29 to 0.39 micron, and average lengths varied from 1.60 to 2.34 microns. Filamentous forms as long as 9.8 microns were observed. Surfaces appeared quite wrinkled compared to that of an Escherichia coli control organism. As seen by transmission electron microscopy, fine structure included a multilayered cell wall characteristic of gram-negative bacteria that was irregular, reflecting wrinkling; plasma membrane; and periplasmic space. Distinct nucleoid, intracytoplasmic ribosomes and rare vacuoles were also seen. No evidence of a spore or an adversity-resistant body was observed.

Adult↗
PubMed1978

Lymphocyte ultrastructure in two cases of neuronal ceroid-lipofuscinosis.

Circulating blood lymphocytes from two patients with neuronal ceroid-lipofuscinosis (NCL) were investigated by transmission electronmicroscopy. Ultrastructural examination showed two forms of intracytoplasmic single membrane-limited inclusions. Contents of the first inclusion form were arranged in five distinct patterns: (1) granules, (2) membranous formations, (3) paracrystalline forms, (4) alternating electron-dense/electron-lucent arrangements, and (5) admixtures of these components. These molecular morphologies suggest the usefulness of lymphocyte fine structure as a diagnostic tool in NCL. The second inclusion form contained cylinder-like structures. These structures are not specific for NCL and have been identified in other diseases.

Ceroid↗
PubMed1976

Peripheral blood elements found in an Egyptian mummy: a three-dimensional view.

Intact peripheral blood elements were found within an intracranial mass, possibly eithern an antemortem subdural hematoma or a postmortem blood clot, removed from a 2200-year-old Egyptian female mummy. Surface topographies of neutrophils and lymphocytes were similar. Some erythrocytes partially retained their biconcave disk shape; others were spherical. Individual platelets exhibited pseudopodia.

Blood Cells↗
PubMed1976

Ultrastructural observations of cytoplasmic inclusions in Tay-Sachs lymphocytes.

Our preliminary study on the circulating leukocytes from two children with Tay-Sachs disease and six heterozygotes from four different families is reported at the levels of both light and transmission electron microscopy. Ultrastructural investigation revealed two types of cytoplasmic inclusions in the lymphocytes of the Tay-Sachs homozygotes. The heterozygotes demonstrated only one of the inclusion forms within the cytoplasm of their circulating lymphocytes. These fine structural observations have not been described previously in Tay-Sachs disease and they may suggest new functional implications for the involvement of the lymphocyte in this storage disorder.

Female↗