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Biomedical subjects

R T Ellison

Publications and source records attributed to R T Ellison.

At least 37 records · Page 2Linked to original sources
PubMed1990

Lactoferrin and transferrin damage of the gram-negative outer membrane is modulated by Ca2+ and Mg2+.

Lactoferrin and transferrin have antimicrobial activity against selected Gram-negative bacteria, but the mechanism of action has not been defined. We studied the ability of lactoferrin and transferrin to damage the Gram-negative outer membrane. Lipopolysaccharide release by the proteins could be blocked by concurrent addition of Ca2+ and Mg2+. Addition of Ca2+ also blocked the ability of lactoferrin to increase the susceptibility of Escherichia coli to rifampicin. Transferrin, but not lactoferrin, increased susceptibility of Gram-negative bacteria to deoxycholate, with reversal of sensitivity occurring with exposure to Ca2+ or Mg2+. In transmission electron microscopy studies polymyxin B caused finger-like membrane projections, but no morphological alterations were seen in cells exposed to EDTA, lactoferrin or transferrin. These data provide further evidence that lactoferrin and transferrin act as membrane-active agents with the effects modulated by Ca2+ and Mg2+.

Calcium↗
PubMed1990

Detection of Listeria monocytogenes by using the polymerase chain reaction.

A method was developed for detection of Listeria monocytogenes by polymerase chain reaction amplification followed by agarose gel electrophoresis or dot blot analysis with a 32P-labeled internal probe. The technique identified 95 of 95 L. monocytogenes strains, 0 of 12 Listeria strains of other species, and 0 of 12 non-Listeria strains.

Bacteria↗
PubMed1988

Purification and characterization of a family of high molecular weight surface-array proteins from Campylobacter fetus.

A variety of Gram-negative and Gram-positive bacteria possess crystalline surface layers, although little is known of their function. We previously have shown that the high molecular weight surface-array proteins of Campylobacter fetus are important in both the pathogenicity and antigenicity of this organism. For biochemical and immunological characterization, we purified high molecular weight (100,000, 127,000, 149,000) surface-array proteins from three C. fetus strains using sequential gel filtration and ion exchange high performance liquid chromatography. These proteins are acidic with pI values between 4.12 and 4.25 and contain large proportions of acidic amino acids (19.7%-22.0%) in addition to hydrophobic amino acids (37.3%-38.5%). They share a novel amino-terminal sequence through at least 19 residues. Carbohydrate analysis using periodic acid-Schiff staining and treatment with trifluoromethanesulfonic acid shows no evidence of glycosylation. Antiserum to a purified Mr = 100,000 protein from C. fetus 82-40 LP cross-reacts with three other purified C. fetus surface-array proteins by enzyme-linked immunosorbent assay with titers greater than 12,800. We conclude that: 1) there is a family of surface-array proteins of C. fetus with common structural and antigenic characteristics; 2) that these molecules have similar biochemical characteristics to surface-array proteins described for other bacteria; but however, 3) by amino-terminal sequence analysis these are unique.

Amino Acid Sequence↗
PubMed1988

Pulmonary secretions accelerate the metabolic rate of Escherichia coli.

A number of studies have suggested that bronchoalveolar lavage fluid (BALF) contributes to intrapulmonary antibacterial host defense, however the mechanisms underlying this interaction have not been defined. To better understand the effect of BALF on bacteria, we measured the metabolism of bacteria in the presence of human or rabbit BALF. Escherichia coli oxygen consumption significantly increases with exposure to BALF (2.9 +/- 0.2 (SEM) nmol/min) compared to incubation in a saline-glucose solution alone (1.8 +/- 0.1); the rate of 1-[14C]-glucose utilization is comparably increased. The effect on oxygen metabolism is dose dependent. The surfactant phospholipids produce a small stimulation of oxygen metabolism, but the major effect is caused by phospholipid-poor material less than 10,000 daltons in size. The activity is heat stable, pH stable, and resistant to the effects of proteases. These studies demonstrate that factor(s) within BALF increase the metabolic rate of bacteria. Further work is required to determine if this bacterial respiratory burst is a pathogenic mechanism or a reparative response to BALF induced injury.

Animals↗
PubMed1988

Damage of the outer membrane of enteric gram-negative bacteria by lactoferrin and transferrin.

Many studies have shown that lactoferrin and transferrin have antimicrobial activity against gram-negative bacteria, but a mechanism of action has not been defined. We hypothesized that the iron-binding proteins could affect the gram-negative outer membrane in a manner similar to that of the chelator EDTA. The ability of lactoferrin and transferrin to release radiolabeled lipopolysaccharide (LPS) from a UDP-galactose epimerase-deficient Escherichia coli mutant and from wild-type Salmonella typhimurium strains was tested. Initial studies in barbital-acetate buffer showed that EDTA and lactoferrin cause significant release of LPS from all three strains. Further studies found that LPS release was blocked by iron saturation of lactoferrin, occurred between pH 6 and 7.5, was comparable for bacterial concentrations from 10(4) to 10(7) CFU/ml, and increased with increasing lactoferrin concentrations. Studies using Hanks balanced salt solution lacking calcium and magnesium showed that transferrin also could cause LPS release. Additionally, both lactoferrin and transferrin increased the antibacterial effect of a subinhibitory concentration of rifampin, a drug excluded by the bacterial outer membrane. This work demonstrates that these iron-binding proteins damage the gram-negative outer membrane and alter bacterial outer membrane permeability.

Cell Division↗
PubMed1987

Recurrent postcoital lower-extremity streptococcal erythroderma in women. Streptococcal-sex syndrome.

Two women with underlying distortion of their lower-body lymphatic systems from neoplasia and surgery or radiation therapy had recurrent episodes of lower-extremity erythroderma temporally associated with sexual intercourse. Both women had vaginal colonization with Streptococcus agalactiae (group B); one was shown to have recurrent bacteremia with this organism at the time of the episodes. Erythroderma developed in these women possibly because of seeding of S agalactiae in the vaginal soft tissues during coitus.

Adult↗
PubMed1986

Effect of aerosolized Escherichia coli and Staphylococcus aureus on iron and iron-binding proteins in lung lavage fluid.

Iron-binding proteins have antibacterial activity; they have been identified in lung secretions, but their role in pulmonary antibacterial defenses is unclear. Murine lactoferrin and murine transferrin were used to generate polyclonal antiserum to lactoferrin and to transferrin, and the specificity of both antisera was shown by western blot. Mice were exposed to either aerosolized Escherichia coli or Staphylococcus aureus; they were killed 1, 4, 24, or 48 hr later; and their lungs were lavaged. We measured the levels of transferrin, lactoferrin, and albumin and did a cell count for the lavage fluid. The predominant iron-binding protein in resting animals was transferrin. Aerosolized E. coli caused a brisk PMNL response in the lungs that was associated with a major increase in the levels of lactoferrin. Challenge with S. aureus was associated with a moderate increase in the number of macrophages and a moderate decrease in the levels of transferrin and iron but no change in the levels of lactoferrin. The levels of iron-binding protein can vary according to the type of inflammatory response.

Aerosols↗
PubMed1986

Meningococcemia and acquired complement deficiency. Association in patients with hepatic failure.

We treated two patients with severe hepatic failure complicated by meningococcemia. Serum complement profiles performed on these patients found low total hemolytic complement assays, normal concentrations of C1q, and low or undetectable concentrations of C3 through C6, C8, C9, and factors B and I. These studies suggest that these patients developed meningococcemia in the setting of acquired complement deficiency from impaired synthesis of multiple complement system proteins.

Acute Disease↗
PubMed1986

Differentiating pyogenic arthritis from spontaneous hemarthrosis in patients with hemophilia.

Pyogenic arthritis in patients with hemophilia is predominantly monoarticular, usually involving the knee, is associated with hemophilic arthropathy and other predisposing factors for infection, is mainly due to Staphylococcus aureus and carries serious morbidity. In patients with hemophilia, it is associated significantly with fever, an increased leukocyte count, knee joint involvement and possible predisposing factors for infection. Such patients presenting with unexplained fever of more than 1 degrees C(1.8 degrees F) and acute symptoms of joint inflammation should have an arthrocentesis.

Adolescent↗
PubMed1985

Rapid nighttime evacuation of a veterans hospital.

Loss of essential utilities and danger of explosion forced a rapid nighttime winter evacuation of 229 patients from an acute-care Veterans Administration hospital. Although distribution of patients to recipient hospitals was not optimal, and the location of several patients could not be documented for more than 24 hours, the evacuation in subfreezing weather went smoothly. Continuity of care and careful planning permitted an orderly return to the hospital five days later. Although financial costs were high, no excess mortality or morbidity was associated with the evacuation. No changes in pharyngeal gram-negative bacterial flora of the patients were noted. Further, a critique is presented to aid in planning for similar emergencies elsewhere.

Colorado↗
PubMed1985

Isolation of an antibacterial peptide from human lung lavage fluid.

The contribution of extracellular secretions to the antibacterial defenses of the lungs remains poorly defined. Recent studies have demonstrated that mouse and rabbit bronchoalveolar washings contain a low-molecular-weight peptide that has antibacterial activity against Escherichia coli. In this study we investigated whether a similar peptide could be identified in human secretions. Bronchoalveolar lavage fluid was obtained from normal volunteers and patients with interstitial lung disease or pulmonary alveolar proteinosis. Cellular material and surfactant lipids were removed from the fluid by sequential centrifugations, and the supernatant was fractionated by exclusion filtration to isolate peptides with a molecular weight less than 10,000. Gel filtration chromatography separated the ultrafiltrate into several peaks, the first of which had antibacterial activity against E. coli. This material was further separated into several hydrophilic peaks by reverse-phase high-pressure liquid chromatography (RPHPLC). All samples had similar RPHPLC graphs. Material from the third RPHPLC peak produced an antibacterial effect similar to that produced by the rabbit and mouse peptide.

Anti-Bacterial Agents↗
PubMed1984

Pyogenic meningitis manifesting during therapy for Aeromonas hydrophila sepsis.

Pyogenic meningitis became apparent on the third day of ampicillin and gentamicin therapy for Aeromonas hydrophila sepsis in a patient with severe alcoholic hepatitis. The patient responded clinically to therapy with intravenous cefotaxime sodium and gentamicin sulfate. Antibiotic therapy that provides adequate CSF concentrations should be considered in the treatment of patients with Aeromonas sepsis.

Adult↗
PubMed1984

Oral rifampin and trimethoprim/sulfamethoxazole therapy in asymptomatic carriers of methicillin-resistant Staphylococcus aureus infections.

During a hospital outbreak of methicillin-resistant Staphylococcus aureus (MRSA) disease in 30 patients we studied the use of rifampin and trimethoprim/sulfamethoxazole (TMP/SMX) in managing asymptomatic carriers. The outbreak persisted despite control measures including "barrier" precautions, screening cultures, identification of affected persons and rapid hospital discharge of affected patients. The MRSA strain was susceptible to both rifampin and TMP/SMX and in vitro the combination was not antagonistic. Fourteen carriers received a five-day course of rifampin and TMP/SMX given by mouth. Twelve patients were evaluable. Cultures remained persistently positive in four patients, three of whom had foreign bodies that could not be removed. Among the eight with an initial response, two relapsed to the carrier state more than six months after treatment. During the study the outbreak resolved. These data suggest that rifampin and TMP/SMX may decrease the number of MRSA-colonized patients, but may not permanently eradicate the MRSA carrier state.

Adult↗
PubMed1983

Prevalence of congenital or acquired complement deficiency in patients with sporadic meningococcal disease.

We evaluated the complement system in 20 patients presenting with a first episode of meningococcal meningitis, meningococcemia, or meningococcal pericarditis. Assays of total serum complement activity were performed prospectively in 12 patients and retrospectively in 8. Six of the twenty patients had a complement deficiency (CH50 greater than 2 S.D. below the normal mean). Three of these six had a deficiency of a terminal-pathway protein (C6 in two and C8 in one), and the other three had deficiencies of multiple complement proteins associated with underlying systemic lupus erythematosus or multiple myeloma. Patients with decreased amounts of complement were similar to normal patients in terms of sex, age, type of infection, and meningococcal serogroup, but 3 of the 6 patients with a complement deficiency were black, as compared with none of the 14 patients with normal function (P = 0.018). Complement deficiency is common in patients with a first episode of meningococcal disease and may be due to either a deficiency in a single terminal protein or a complement-depleting underlying illness.

Adolescent↗