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C P Davis

Publications and source records attributed to C P Davis.

At least 73 records · Page 4Linked to original sources
PubMed1982

Klebsiella pneumoniae-induced experimental pyelitis: the effect of piliation on infectivity.

The effect of bacterial piliation on the infectivity of Klebsiella pneumoniae in the renal pelvis was examined by means of piliated and nonpiliated variants derived from a single parent strain. Piliated-phase variants were significantly more infective as determined by viable counts of bacteria isolated from the kidneys at the time of sacrifice. In addition, scanning electron microscope was used to examine the renal pelvis for evidence of infection. Kidneys infected with piliated-phase organisms exhibited greater tissue damage -- both in the magnitude of tissue alterations observed and in the number of kidneys affected. Thus, it is concluded that piliation contributes to the ability of K. pneumoniae to infect the renal pelvis following reflux from the bladder.

Animals↗
PubMed1982

Calcium phosphate crystal formation in Escherichia coli from human urine: an in vitro study.

Escherichia coli with no demonstrable urease activity was inoculated into filter sterilized urine obtained from a healthy volunteer subject with no history of stone disease and then incubated at 37 degrees C. Bacteria were recovered at intervals between 1 and 10 days. Urinary pH was stable as compared to control urines and spontaneous crystal precipitation was not noted in controls. Recovered organisms were analyzed by x-ray powder diffractometry. An uncharacterized mineral phase (UMP) was first evident after 6 days. Calcium phosphate in the form of brushite and hydroxyapatite was apparent at 7 and 10 days respectively. This suggests a role for bacteria in calcium phosphate crystal formation in urine apart from urease activity and may contribute to the calcium phosphate component of urinary calculi.

Calcium Phosphates↗
PubMed1982

Immunoglobulin A and secretory immunoglobulin A antibodies to purified type 1 Klebsiella pneumoniae pili in human colostrum.

Immunoglobulin A antibodies with binding specificity for purified Klebsiella pneumoniae type 1 pili were detected by an enzyme-linked immunosorbent assay in 20 of 21 human samples (95%). The concentrations of secretory immunoglobulin A antibody in colostrum directed against the pili were calculated by comparison of experimental enzyme-linked immunosorbent assay values with values obtained from known secretory immunoglobulin A concentrations. The presence of antibodies to K. pneumoniae type 1 pili was confirmed by double diffusion-gel studies with selected specimens of colostrum. This study shows that in the majority of human colostral samples examined, secretory immunoglobulin A antibodies with specificity for K. pneumoniae type 1 pili can be commonly found in variable, but frequently high, concentrations.

Adolescent↗
PubMed1982

Relationship between phagocytosis and immunoglobulin A release from human colostral macrophages.

Macrophages and neutrophils that contain mainly secretory immunoglobulin A (IgA) comprise the majority of cells in human colostrum. These cell populations were separated and analyzed for their ability to release total IgA and secretory IgA when stimulated to phagocytose. Colostral macrophages phagocytosed opsonized bacteria and nonopsonized latex particles; at the same time, IgA was released. Neutrophils poorly phagocytosed opsonized bacteria but actively phagocytosed latex particles. In contrast to the macrophages, the neutrophils did not release IgA, even after active phagocytosis of latex. Consequently, colostral macrophages are the main source of IgA released from colostral leukocytes when these cells are exposed to organisms or particles that are phagocytosed. A function for colostral neutrophils which sequester IgA is proposed.

Adolescent↗
PubMed1982

Iontophoretic killing of Escherichia coli in static fluid and in a model catheter system.

A static iontophoretic model system was used to determine the effects of various metals, microamperage (microamperemeter) levels, and voltage levels on Escherichia coli and several other bacterial genera. Only gold iontophoresis at 400 microamperemeter and approximately 3.2 V was found to kill all bacterial genera tested when the inoculum dose was 1 x 10(3) cells per ml. E. coli was killed at all inocula doses to 1 x 10(7), whereas other genera were inhibited. Other metals, such as silver or copper, were not effective in killing bacteria. A model catheter system, which contained a gold iontophoresis device, was used to kill E. coli in a flowing system at sites as far as 10 cm downstream from the iontophoretic device. The experiments suggest gold iontophoresis can be a potential tool in controlling catheter-related infections.

Equipment Design↗
PubMed1982

Evaluation of bacterial attachment to acid treated bladder epithelium.

The technique of rapid (60 seconds) acid treatment of intact rat bladders was used to evaluate bacterial interactions with bladder mucin and mucosal cells. Using the rat model system, SEM indicated that short term acid treatment removed the mucin layer but it also modified the bladder epithelial cell surface. Although the treatment which removed mucin allowed an increase in random bacterial attachment, the increase could also be attributable to acid modification of the mucosa. Examination of acid treated rabbit bladders also showed mucin removal and simultaneously bladder epithelium modification. We conclude that short term acid treatment removes mucin, modifies the epithelial layer, and appears to nonspecifically increase bacterial attachment on the mucosa by modifying the mucosal surface.

Animals↗
PubMed1981

Intracellular crystal formation in bacteria from human urines: a contributing factor in urinary calculi.

Understanding of the bacterial contribution to urinary calculi has been limited to those organisms capable of altering the urine through urease activity. Sterilized urines from stone forming and non-stone forming individuals were inoculated with bacteria having either strong, weak, or no urease activity. All organisms grown in unbuffered urines produced crystallization (calcite or apatite) as demonstrated by X-ray diffraction. Bacteria grown in conventional medium (Heart Infusion broth) did not demonstrate crystal formation. Unstained specimens revealed electron-dense deposits within bacteria grown in urine. Deposits were not present in organisms grown in conventional media. Analysis revealed increased levels of calcium within these deposits as compared to extracellular levels. These findings support the hypothesis that both urease producing an non-urease producing organisms may accumulate calcium crystals intracellularly and form nidi for calculus formation.

Apatites↗
PubMed1981

Osteopetrosis: a scanning electron microscopic study.

Scanning electron microscopic investigation was conducted with bone in a case of osteopetrosis by comparing it with normal cortical bone. The fractured surface of the osteopetrotic bone was devoid of the orderly constructed lamellar haversian system seen in normal bone. It was occupied by a massive smooth cartilaginous matrix containing scattered rough areas of abnormal ossification. Tortuous channels were randomly distributed and corresponded to the abortive marrow spaces. The presence of many irregular fracture lines reflected the fragility of the bone. The findings support the concept of defective remodeling in the pathogenesis of osteopetrosis and provide a further explanation for the abnormal fragility of bone in osteopetrosis.

Adult↗
PubMed1981

Enhanced immunoglobulin, A release from human colostral cells during phagocytosis.

Human colostral leukocytes were investigated for their ability to release immunoglobulin A during phagocytosis of latex particles, heat-killed Candida albicans, or live Escherichia coli. Leukocytes readily phagocytosed latex or serum-opsonized candida or the E. coli. Colostral fluid was also opsonic for yeast and bacteria. Immunoglobulin release, which consisted mainly of secretory immunoglobulin A, began during the first 15 min of incubation with latex, opsonized yeast, or opsonized bacteria. Release was significantly increased from control levels by 30 or 60 min. The release of immunoglobulin A could be inhibited by incubating leukocytes at 4 degrees C. We conclude that phagocytosis and immunoglobulin A release by human colostral leukocytes are related. The data support the hypothesis that colostral leukocytes may play an active role in protecting infants from pathogenic microorganisms.

Candida albicans↗
PubMed1981

Evidence for a bladder cell glycolipid receptor for Escherichia coli and the effect of neuraminic acid and colominic acid on adherence.

The rat bladder epithelial cell receptors involved in mannose-sensitive adherence of Escherichia coli strains were studied. Sodium metaperiodate and lipase pretreatment of epithelial cells significantly reduced bacterial adherence to cells whereas trypsin and phospholipase C had a marginal or insignificant effect on adherence. Neuraminidase and colominic acid significantly increased adherence, whereas N-acetylneuraminic acid significantly reduced adherence. These data suggest that the rat bladder epithelial cell receptors involved in mannose-sensitive adherence are glycolipids. In addition, the data suggested that sialic acid on bladder epithelial cells acts as a nonspecific inhibitor of adherence, whereas colominic acid, a component of some E. coli K1 capsules, may act as a promoter of adherence.

Animals↗
PubMed1981

Environmental alteration and two distinct mechanisms of E. coli adherence to bladder epithelial cells.

We used an in vitro model to investigate Escherichia coli attachment to transitional epithelial cells obtained from bladders of female rats. Adhesive abilities and sensitivity to mannose inhibition differed among the isolates for both epithelial cells and erythrocytes. Adherence of some strains could be modulated by bacterial washes and growth media. Variations in adhesiveness were related to bacterial piliation as determined by transmission electron microscopy. With two strains, mannose inhibition of adherence to epithelial cells was dose-related; however, with a maximal inhibitory dose, adherence was reduced by approximately 80 per cent even when the bacteria-to-epithelial cell ratio was varied. These studies show that adhesiveness and piliation of certain adhesive E. coli strains are either reduced or enhanced by environmental alterations. We conclude that E. coli strains adhere to epithelial cells by at least two distinct mechanisms and that a single isolate may utilize both mechanisms. The more efficient process is pili-mediated and inhibited by mannose whereas undetermined surface components mediate the less efficient but mannose-resistant mechanism.

Animals↗
PubMed1981

Papillary necrosis in vitro: a scanning electron microscopic comparison of escherichia coli and Proteus mirabilis infection.

The effect of bacterial infection on excised renal papillae as a model for papillary necrosis and subsequent calcification was investigated. Sterile rat renal papillae were placed in 25 ml aliquots of filter sterilized human urine and then inoculated with one ml suspensions of sterilized human urine and then inoculated with one ml suspensions of sterile saline as a control, or 1 x 108/ml Escherichia coli or proteus mirabilis. After incubation at 37 degrees C for periods of 8 hr, 24 hr, 48 hr, 72 hr, 1 wk, 2 wk and 3 wk, urinary pH was measured, bacterial culture performed and the renal papillae were recovered and examined by scanning electron microscopy (SEM) and energy dispersive spectrophotometry (EDS). In the case of Proteus mirabilis, the sequence of events noted included bacterial-papillary interactions consisting of cell desquamation and strand formation, despite infrequent bacterial attachment. After 10 hr, a rapid, urease induced pH rise resulted in calcium salt deposition on the papillae surface. Organism death was apparent after 72 hr. Escherichia coli infected papillae demonstrated similar cell surface changes after a 8 hr as seen in P. mirabilis; however, frequent evidence of bacterial attachment and penetration was apparent. Bacterial attachment was a prominent feature throughout the incubation period with E. coli. After one week, rare areas of degenerating cells and bacteria with increased calcium levels as compared to surrounding areas were noted by EDS analysis. Urinary pH was stable throughout the incubation period. This study suggests varied roles for the organisms most associated with infection induced papillary necrosis (E coli) and papillary necrosis with subsequent stone formation (P. mirabilis). A role for bacterial calcification in the absence of bacterial urease activity by E. coli is also suggested.

Animals↗
PubMed1980

Effect of piliation on Klebsiella pneumoniae infection in rat bladders.

The possible role of pili in the pathogenesis of urinary tract infection caused by Klebsiella pneumoniae was investigated in a rat model of cystitis by utilizing piliated- and nonpiliated-phase organisms derived from a single parent strain. Bladder surfaces were examined for evidence of infection by scanning electron microscopy. In animals infected with piliated-phase organisms, foci of infection were evident in the majority of bladders examined. Rat bladders associated with nonpiliated-phase bacteria showed little evidence of infection. The ability of methyl-D-mannoside, a known inhibitor of pilus-mediated adherence to mammalian cells, to protect the bladder surface from colonization was also tested. The results showed a significant decrease in the ability of piliated-phase K. pneumoniae to establish infection in bladders. These observations suggest that pili may play an integral role in the ability of K. pneumoniae to cause urinary tract infections by mediating the attachment of the bacteria to the uroepithelial surface.

Animals↗
PubMed1980

Complement-independent adherence of Escherichia coli to complement receptors in vitro.

We studied adherence to human cells by a strain of Escherichia coli. Adherence to erythrocytes was assessed directly by phase-contrast microscopy and indirectly by hemagglutination; adherence to peripheral blood leukocytes, using radiolabeled bacteria and subsequent determination of leukocyte-associated radioactivity; and adherence to renal glomeruli, by microscopy of fluoresceinated bacteria and of Gram-stained nonfluoresceinated bacteria. In serum-free systems, E. coli of this strain adhered to human erythrocytes, which have surface receptors for the third component of complement (C3), but not to erythrocytes from species lacking this receptor. 1 mM trypan blue, a reagent that inhibits complement receptor function, inhibited adherence to human erythrocytes, as well as adherence to leukocytes and glomeruli. Preincubation of erythrocytes and leukocytes with complement-coated zymosan particles partially blocked subsequent bacterial adherence. Incubation of human erythrocytes with aging human serum, with trypsin-cleaved C3, or with C3 cleaved by the classical pathway convertase (EAC142)-all of which treatments deposited C3 on the erythrocyte surface, presumably at C3 receptors-inhibited subsequent E. coli adherence. Finally, incubation of E. coli with rabbit antiserum to human C3 blocked adherence to erythrocytes.Bacterial hemagglutination and erythrocyte adherence were not inhibited by mannose in concentrations up to 2.5%. And this strain of E. coli did not adhere to or agglutinate guinea pig erythrocytes, the usual test particle used for demonstration of common pili. Finally, electron microscopy of adherent bacteria showed only rare surface pili. In contrast, adherence to and agglutination of guinea pig erythrocytes by a stock piliated E. coli was inhibited by mannose but not by trypan blue. We conclude that organisms of this strain of E. coli adhere to human erythrocytes, leukocytes, and glomeruli at complement receptors. Complement is not required for this interaction. Adherence apparently involves a C3-like structure on the bacterial surface, but bacterial surface pili play no role. The physiological or pathological role of this adherence is not apparent, but study of this phenomenon may elucidate functions of complement receptors on various cells.

Animals↗
PubMed1980

Ultrastructure of Sarcocystis sporocysts from passerine birds and opossums: comments on classification of the genus Isospora.

Sporocysts were obtained from the feces of opossums (Didelphis virginiana) which had been fed muscles of passerine birds (Molothrus ater and Cassidix mexicanus) infected with Sarcocystis. Sporocysts were examined by phas microscopy and scanning and transmission electron microscopy. Ridges on the surface of the sporocysts outlined four plates. Thin sections of the sporocyst wall showed thickened regions and gaps interpreted as cross sections of the ridges. The sporocyst wall has four major layers with a thick, granular inner layer which resembles the inner layer of sporocysts of related species. Excystation structures are discussed as a basis for classifying disporocystic coccidia to correlate with Frenkel's (1977) life cycle classification of this group.

Animals↗
PubMed1980

Postmortem alterations of bacterial localization.

Localization of bacteria in mammalian gastrointestinal tracts by electron microscopy has yielded much information on our understanding of intimate host-microbial interactions, but because of difficulties in obtaining human tissue, the human host-microbial interactions have not been well studied. In this report, an attempt was made to ascertain the feasibility of using gastrointestinal tissues obtained at autopsy. A rat model was used to produce samples that would simulate conditions that autopsy samples might undergo. Rats, left at room temperature for 1 hr and then refrigerated at 2C for time intervals up to 24 hours after death were autopsied and samples from the stomach, ileum and cecum were removed and processed for light and scanning microscopy. Tissues were fixed in buffered glutaraldehyde, postfixed in buffered osmium tetroxide, dehydrated in an ethanol series, critical point dried, coated with gold-palladium and examined. Keratinized murine stomachs showed little or no changes in the localization of the gram-positive layer of bacteria over 24 hours. However, major changes were noted in the ileum and colon with the ileum showing the most dislocation of the flora. Colonic tissues were altered by invading bacteria although some regions had a relatively normal appearing host-flora relationship. Slow cooling rates of the gastrointestinal tracts were implicated as a major cause for alterations in bacterial localization. The data predict that studies of normal microbial location with human autopsy samples will be best pursued on keratinized tissue.

Animals↗