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C H Dorsey

Publications and source records attributed to C H Dorsey.

At least 19 recordsLinked to original sources
PubMed1992

Encapsulation and pilus formation of Bacteroides spp. in normal flora abscesses and blood.

The presence of encapsulated and piliated Bacteroides spp. (mostly Bacteroides fragilis and melaninogenicus groups was investigated in isolates from blood, abscesses and normal flora. Of the strains of Bacteroides spp. isolated 45 of 54 (83%) recovered from blood and 31 of 40 (78%) found in abscesses were encapsulated. In contrast, only seven of 71 (10%) similar strains isolated from the faeces or pharynx of healthy persons were encapsulated (P < 0.001). Pili were observed in three of 54 (6%) of strains isolated from blood, 30 of 40 (75%) of those recovered from abscesses (P < 0.001), and 49 of 71 (69%) of those found in normal flora (P < 0.001). The predominance of encapsulated forms in all strains of B. fragilis and B. melaninogenicus in blood as well as in abscesses suggests an increased virulence of these compared with non-encapsulated isolates. In contrast, the presence of pili in Bacteroides spp. recovered mostly from abscesses and normal flora suggests that this structure may play a role in the ability of these organisms to adhere to mucous membranes and may interfere with their ability to spread systemically. These findings illustrate the morphological differences that may be observed in Bacteroides spp. from various anatomical sites.

Abscess↗
PubMed1991

Nervous system of Schistosoma mansoni cercaria: organization and fine structure.

As observed by transmission electron microscopy of serially sectioned Schistosoma mansoni cercaria, the nervous system is distributed throughout the three anatomic segments of the larva-i.e., the anterior organ (oral sucker), the body (midsegment), and the tail. The central ganglion, a neuropile surrounded by cell bodies, is located in the anterior area of the body segment. It tapers anteriorly into two lobes from which a pair of anterior central nerve trunks extend longitudinally. The posterior region of the central ganglion tapers into a pair of nerve trunks (posterior central nerve trunks). Twelve peripheral nerve trunks are evenly distributed around the ganglion. Six trunks course anteriad (anterior peripheral nerve trunks) and six course posteriad (posterior peripheral nerve trunks). A pair of dorsal and ventral nerve trunks, positioned opposite each other, extend the length of the tail. All nerve trunks are unsheathed. The nervous system contains three types of vesicles. Type I vesicles average 47.66 +/- 2.57 nm in diameter, vary in electron density, and have electron-lucent peripheries. Type II vesicles have a mean diameter of 18.41 +/- 2.57 nm, are electron-lucent and are concentrated mostly in the presynaptic area of the synaptic and neuromuscular junctions. The mean diameter of Type III vesicles is 57.47 +/- 16.08 nm. They are electron-dense and are concentrated mostly in the tegumental ciliated papillae and their accompanying dendrites. Two types of synaptic junctions are present.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Schistosoma mansoni: a new parenchymal cell in cercariae.

A new type of cell has been identified in cercariae of Schistosoma mansoni. The perikarya (cell bodies) of these cells were located in the body (midsegment), in an area oral to the acetabulum (ventral sucker). Cytoplasmic processes extending from the perikarya ramified throughout the parenchyma of the anterior organ (oral sucker), body, and tail segments by following the path of the nerve processes from the neuropile. The perikarya of these cells had heterochromatic nuclei and a predominance of particulate material and granules (240-360 nm) in their cytoplasm. Aggregates of granules (240-360 nm) and associated vesicles (34 nm) were scattered throughout the cytoplasmic processes of the cells and formed distinct varicosed areas. These processes often connected to the tegument in the midsegment (body) of the cercariae. The granules and associated vesicles reacted (became electron dense) with fixatives reported to be detectors of biogenic amines: The glutaraldehyde/osmium tetroxide fixation procedure rendered the granules electron dense while the glutaraldehyde/chromate/osmium tetroxide fixation procedure rendered the granules and the associated vesicles electron dense. The chromate solution of the latter procedure was responsible for the electron density of the associated vesicles. The morphology of these cells (their long ramifying cytoplasmic processes) and their reaction to chromium suggests that they are probably biogenic aminergic sensory cells.

Animals↗
PubMed1985

Mechanisms of immunity to infection with typhus rickettsiae: infected fibroblasts bear rickettsial antigens on their surfaces.

As with any immune response to infectious organisms, both antibody and T cell-mediated immune responses to infection with Rickettsia typhi require the appropriate presentation of rickettsial antigens to immunocompetent cells. Considering the obligate intracellular nature of rickettsiae, the exact mechanisms by which lymphocytes and macrophages encounter and respond to rickettsial antigens may depend on certain aspects of pathogenesis and on the availability of organisms or their antigens to cells of the immune system. One potential mode of rickettsial antigen presentation, not previously identified, is the appearance in vitro of rickettsial antigens on the cell membrane of R. typhi-infected L-929 fibroblasts. Polyvalent fluoresceinated rabbit antisera directed against whole R. typhi cells used in flow cytometric analysis of infected fibroblasts showed an increasing presence of R. typhi antigen on the host cell membrane 1 to 3 days postinfection. The significance of this finding in the pathophysiology of rickettsia-host interactions and the generation of cytotoxic T cell-mediated immunity and antibody immunity is discussed.

Animals↗
PubMed1984

Anisotropic diffusion of oxygen in slices of rat muscle.

The diffusion coefficient of oxygen (D) and the fluorescence quenching coefficient (K') of pyrenebutyric acid (PBA) were measured in sections of rat hamstring muscles. Values of D and K' at temperatures (Tc) of 20, 30, and 40 degrees C were determined and referred to the values in water. In sections cut parallel to the muscle fibers, D = DH2O (0.380 +/- 0.038), whereas in sections cut across the grain of the fibers, D = DH2O (0.985 +/- 0.039). Oxygen diffuses along the length of a muscle fiber over twice as rapidly as it diffuses in directions perpendicular to the long axis of the fiber. This suggests that fibers, myofibrils, or myofilaments offer substantial barriers to the diffusion of oxygen, whereas extracellular space and spaces around fibers or myofibrils or myofilaments offer no more resistance than water to the diffusion of oxygen. Corresponding estimates for K' were K' = K'H2O[0.14 (1 + 0.25 Tc)] and K' = K'H2O[0.21 (1 + 0.25 Tc)] for slices cut parallel to the long axis of muscle fibers and across the long axis, respectively. Standard deviations of K' were 9%.

Animals↗
PubMed1983

Schistosoma mansoni: stimulus and transformation of cercariae into schistosomules.

Schistosoma mansoni schistosomules prepared from cercariae by seven in vitro techniques had not all reached the same state of development at the end of the incubation period as scored by seven parameters: water tolerance; Cercarienhüllen Reaktion; presence of the glycocalyx; condition of the surface membrane; nuclear state; granule migration; and cryopreservability. At the end of the specific incubation period for each technique, the level of development was judged with respect to schistosomules which had developed in situ for 1 hr after penetration of the ear skin of mice. In descending order of their correspondence to in vivo schistosomules, those derived in vitro (by the procedures listed) ranked as follows: first, penetration of dried rat skin; second, centrifuging and vortexing, or incubation in serum-supplemented medium; and third, syringe passage, omnimixing, centrifuging, and incubating, or incubating alone. The only treatment common to all techniques was incubation in 37 C culture medium for 2 hr or more. This is suggested as the stimulus for the cercaria-to-schistosomule transformation.

Animals↗
PubMed1977

Schistosoma mansoni: localization of calcium-detecting reagents in electron-lucent areas of specific preacetabular gland granules.

In an attempt to establish the exact location of calcium within the preacetabular glands of cercariae of Schistosoma mansoni, these larvae were exposed to reagents (potassium oxalate, potassium pyroantimonate, chloranilic acid, and silver nitrate) useful in the detection of calcium, and were subsequently observed with the aid of light and electron microscopes. Cercariae incubated in potassium oxalate and viewed in polarized light showed birefringence only in the preacetabular gland funduses. At the ultrastructural level, the preacetabular glands of potassium oxalate-treated cercariae had no electron-dense precipitate, but instead had translucent, irregularly shaped inclusions, similar to spaces left by volatilized calcium oxalate as described by others. Pyroantimonate treatment, on the other hand, localized the reaction in the electron-lucent areas of the light-spotted granules. The von Kossa silver nitrate procedure destroyed the secretory granules; therefore, an electron-dense precipitate was distributed throughout the gland. However, pretreatment with chloranilic acid before fixation preserved the granules, and subsequent exposure to the von Kossa silver nitrate gave a reaction identical to that obtained with the pyroantimonate alone. When viewed in polarized light, chloranilic acid-incubated cercariae showed birefringence in the fundus and duct areas.

Animals↗