Search PubMed⌕ Search

Biomedical subjects

G E Lewis

Publications and source records attributed to G E Lewis.

At least 37 records · Page 2Linked to original sources
PubMed1985

Continuous propagation of Ehrlichia sennetsu in murine macrophage cell cultures.

Ehrlichia sennetsu, the etiologic agent of human sennetsu rickettsiosis was successfully propagated in a continuous cell culture using murine cell lines P388D1 and Raw 264. Pleomorphic cytoplasmic inclusion bodies similar to Ehrlichia canis morulae were observed 3-4 days after second post-inoculation split. In the Raw 264 cell line E. sennetsu was not seen until the third passage. Relatively heavier infection was observed in P388D1 than in Raw cell line. The latter reached a maximum of 15% infection whereas P388D1 cell line attained saturation. Structural details of the organism were confirmed by electron microscopy. A unique rippled cell mass surrounding the plasma membrane was observed. Supernatants of cultures were shown to contain infectious organisms. The advantages of propagating E. sennetsu in continuous cell lines are discussed with respect to future physiochemical and immunochemical studies of this organism.

Animals↗
PubMed1985

A scanning and transmission electron microscopic examination of Rickettsia tsutsugamushi-infected human endothelial, MRC-5, and L-929 cells.

Monolayers of primary human endothelial cells were infected with the Karp strain of Rickettsia tsutsugamushi and examined by scanning and transmission electron microscopy. The results were compared with those obtained with similarly infected L-929 and MRC-5 cells and with uninfected cells of all three types. The rickettsiae grew to slightly higher titers in the human endothelial cells. Transmission electron microscopy revealed significant changes in the host cell organelles; a reduction in ribosome-coated endoplasmic reticulum and in Golgi activity, swelling of mitochondria, and an increase in vacuolation within the cytoplasm. Since human endothelial cells are known to retain their in vivo structural and functional qualities when cultured in vitro, it is likely that these effects are similar to those which occur during the infectious process in human scrub typhus.

Animals↗
PubMed1985

A light and electron microscopic examination of Ehrlichia sennetsu in cultured human endothelial cells.

Umbilical cord-derived human endothelial cells were used for the propagation of Ehrlichia sennetsu. Scanning electron microscopic studies revealed numerous pleomorphic ehrlichiae extending from the surface of infected human endothelial cells. Transmission electron microscopic examination of the cells revealed E. sennetsu-induced cytopathic changes at the ultrastructural level. Ehrlichiae of variable size, shape and density were located individually and in clusters enclosed within membrane lined vacuoles. The cultured human endothelial cell provides an optimal environment for the growth of E. sennetsu and is a suitable in vitro model for the study of the cytopathic effects of this human pathogen.

Animals↗
PubMed1985

Pathology of toxic death in mice following intravenous injection of Rickettsia tsutsugamushi strain gilliam: examination by light and scanning electron microscopy.

The pathologic manifestations of the toxic death elicited by the iv injection of mice with Rickettsia tsutsugamushi strain Gilliam were examined by light and scanning electron microscopic techniques to ascertain the cause of death. Light microscopic examinations of hematoxylin and eosin-stained sections of organs suggested the presence of fluid in the lungs; this was confirmed by an increase in the weight of the lungs of moribund mice. Scanning electron microscopy of blood cells demonstrated a marked crenation of erythrocytes from these mice. Death appears to be the result of shock brought on by vascular collapse secondary to plasma leakage.

Animals↗
PubMed1984

Antitoxin levels in botulism patients treated with trivalent equine botulism antitoxin to toxin types A, B, and E.

Serum levels of equine-botulism antitoxin to toxin types A, B, and E were measured in four type-A botulism patients who had received equine-botulism antitoxin. High circulating levels capable of neutralizing in excess of 1 X 10(8), 9 X 10(7), and 6 X 10(6) 50% mouse lethal doses of toxin of types A, B, and E, respectively, were detected. There was little depletion of type-A antitoxin even though two of the patients had circulating type-A toxin before treatment. The half-life for antitoxin persistence for one patient was calculated as being 6.5, 7.6, and 5.3 days for antitoxin types A, B, and E, respectively. Antitoxin levels were not proportionate to the amount (range, 2-4 vials) injected and did not appear to be affected by whether the route of administration was iv or im. Peak serum levels of antitoxin were 10-1,000 times higher than amounts needed to neutralize the toxin measured in the serum of these and other patients with botulism.

Botulinum Antitoxin↗
PubMed1981

Detection of Clostridium botulinum type G toxin by enzyme-linked immunosorbent assay.

Clostridium botulinum type G toxin was detected and quantified readily with the enzyme-linked immunosorbent assay. With the double-sandwich technique and alkaline phosphatase as the enzyme indicator, C. botulinum toxin type G was detected in quantities equaling those required for one mouse intraperitoneal median lethal dose. The time required for the procedure was approximately 6.5 h, but this requirement could have been reduced to 5.5 h or less with the use of precoated plates stored at -70 degrees C. Cross-reactions did not occur with culture extracts of C. sporogenes of C. botulinum types B, C, D, E, and F. Acidic preparations of C. botulinum type A exhibited nonspecific reactivity. Likewise, 50% of the C. subterminale isolates tested were cross-reactive in the assay. These latter isolates express similar metabolic and physiological characteristics with C. botulinum type G.

Bacterial Toxins↗
PubMed1980

Serial propagation of Ehrlichia canis in primary canine peripheral blood monocyte cultures.

Cultures of primary canine monocytes were prepared from blood to which dextran (3%) had been added to enhance sedimentation of the erythrocytes. Homogeneous populations of monocytes were observed by 5 days after seeding, and some cultures were maintained as long as 30 days. The monocyte cultures were used successfully for the serial passage of Ehrlichia canis. After the 3rd passage, small intracytoplasmic inclusions of E canis were detected by 60 hrs after inoculation and greater than 90% of the monocytes were infected by 7 days. In vitro propagated ehrlichiae were preserved at -80 C for at least 31 months with minimal loss of infectivity. Following 125 in vitro passages E canis induced signs of ehrlichiosis in experimentally infected dogs.

Animals↗
PubMed1978

Immune response of ponies to experimental infection with Ehrlichia equi.

Four ponies experimentally infected with Ehrlichia equi developed substantial cell-mediated immune responses, as measured by the leukocyte migration-inhibition test. Serum anti-E equi antibodies up to 1:1,280 were demonstrated by the indirect fluorescent antibody test. Cell-mediated immune responses returned to a base-line value by day 200 after primary inoculation, but serum antibody titers persisted for at least 300 days after inoculation. Two additional susceptible ponies, which were inoculated with convalescent blood or organ homogenates from ponies recovered from acute equine ehrlichiosis, treated with tetracycline, and subsequently challenge exposed with E equi-infective blood, did not develop clinical disease. This study suggested that ponies are resistant to reinfection with E equi following clinical ehrlichiosis.

Animals↗
PubMed1978

Effect of canine immune serum on the growth of Ehrlichia canis within nonimmune canine macrophages.

The effect of canine immune serum (CIS) on the growth of Ehrlichia canis was studied in macrophage cultures derived from peripheral blood monocytes of normal dogs. Ehrlichiae treated with canine normal serum and then introduced into normal macrophage cultures maintained in canine normal serum multiplied within the macrophages and destroyed them. Immune serum, collected from E canis carrier dogs, suppressed ehrlichial growth in normal macrophages. An inverse relationship existed between the amount of CIS to which ehrlichiae were exposed and the growth of the organism in normal macrophages. The anti-E canis activity was most prevalent in the 7-S fraction of immune serum. Fresh CIS had a greater suppressive effect on the growth of E canis than did heat-inactivated CIS. Antibody cytophilic for canine monocyte-derived macrophages was not detected in CIS.

Animals↗
PubMed1978

Effect of canine immune macrophages and canine immune serum on the growth of Ehrlichia canis.

The effect of canine immune macrophages and canine immune serum (CIS) on the growth of Ehrlichia canis was studied in vitro. Treatment of E canis organisms with CIS before they were inoculated into immune macrophage cultures, coupled with pre- and postinoculation maintenance of cultures in CIS, suppressed macrophage infection rates to 1% or less. Immune macrophages collected from E canis-carrier dogs and maintained in canine normal serum were more resistant to the intracellular growth of E canis than were normal macrophages maintained in the same serum. Ehrlichiae introduced into normal macrophage cultures maintained in canine normal serum multiplied within the macrophages and destroyed them. Maximal immunity to intracellular growth of E canis, maximal destruction of this organism, or both, required the interaction of E canis with both humoral and cellular factors in proper sequence.

Animals↗
PubMed1977

The brown dog tick Rhipicephalus sanguineus and the dog as experimental hosts of Ehrlichia canis.

Adult Rhipicephalus sanguineus ticks efficiently transmitted Ehrlichia canis to susceptible dogs for 155 days after detachment as engorged nymphs from a dog in the acute phase of ehrlichiosis. Adult ticks that had similarly engorged on a dog in the chronic phase of ehrlichiosis failed to transmit E canis to susceptible dogs. Infected but unfed adult ticks may be of greater importance than the chronically infected carrier dog as a natural reservoir of E canis.

Animals↗
PubMed1976

Ultrastructural observations on Ehrlichia equi organisms in equine granulocytes.

The ultrastructure of the etiological agent of equine ehrlichiosis, Ehrlichia equi, was studied in equine peripheral leukocytes. The organisms occurred within membrane-lined cytoplasmic vacuoles of neutrophils and eosinophils. Ovoid, round, and rod-shaped profiles were observed. From 1 to 33 organisms were present in a thin-section profile of a cytoplasmic vacuole. Many cells contained multiple organism-containing vacuoles. The organisms had a cell wall and plasma membrane, and internally they consisted of electron-dense and lucid areas. A great variation in size was observed. The morphological features were most consistent with agents of the genus Ehrlichia.

Animals↗
PubMed1975

Experimentally induced infection of dogs, cats, and nonhuman primates with Ehrlichia equi, etiologic agent of equine ehrlichiosis.

Dogs (German Shepherd Dogs and Beagles), cates, rhesus macaques (Macaca mulatta), and baboons (Papio anubis) were inoculated with Whrlichia equi, the etiologic agent of equine ehrlichiosis. Within 3 to 7 days after inoculation, morulae were observed in the eosinophils of cats, neurtrophils of macaques and baboons, and in both neutrophils and eosinophils of dogs. The severe disease produced in horses by this agent was not a feature of E equi infection in dogs, cats, macaques, and baboons. However, a susceptible horse, inoculated with the pooled blood of 2 infected macaques, developed severe clinical signs of equine ehrlichiosis. Infection with E equi did not alter the susceptibiltiy of dogs to infection with Ehrlichia canis and did not prevent development of signs of disease resulting from this infection. The broad experimental host range from this infection. The broad experimental host range of E equi distinguishes it from other ehrlichial agents which are characterized by a rather narrow host range. The susceptibiltiy of nonhuman primates to infection with E equi provides a basis for consideration of the potential transmission of ehrlichial agents to man.

Animals↗