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T F Murphy

Publications and source records attributed to T F Murphy.

At least 91 records · Page 5Linked to original sources
PubMed1991

Molecular conservation of the P6 outer membrane protein among strains of Haemophilus influenzae: analysis of antigenic determinants, gene sequences, and restriction fragment length polymorphisms.

Infections caused by Haemophilus influenzae are a major worldwide health problem. In particular, nontypeable strains of H. influenzae are a common cause of otitis media in infants and children. A vaccine to prevent these infections would result in the prevention of substantial morbidity and cost savings. A problem in identifying an appropriate vaccine antigen has been the enormous antigenic heterogeneity among nontypeable strains of H. influenzae. The present study was undertaken to characterize the conservation of the P6 outer membrane protein (approximately 16,000 daltons) among strains of H. influenzae. A total of 20 type b strains and 20 nontypeable strains of diverse geographic and clinical origins was studied. Three approaches were taken. (i) Antigenic determinants recognized by monoclonal and polyclonal antibodies were present on P6 in all 40 strains tested. The molecular weight of P6 was identical in all strains. (ii) Comparison of the DNA sequences of the P6 genes from three epidemiologically and serologically unrelated strains demonstrated 100% homology at the amino acid level and 97 to 99% homology at the nucleotide level. (iii) Restriction fragment length polymorphism analysis demonstrated that the P6 gene and flanking sequences were highly conserved among all strains. These three independent series of experiments indicated that the P6 protein is highly conserved among strains of H. influenzae. P6 should receive serious consideration for inclusion in a vaccine to prevent infections caused by nontypeable H. influenzae.

Amino Acid Sequence↗
PubMed1991

Spontaneous pneumothorax in AIDS patients with recurrent Pneumocystis carinii pneumonia despite aerosolized pentamidine prophylaxis.

Aerosolized pentamidine prophylaxis for Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome (AIDS) may predispose these patients to recurrent apical Pneumocystis infection. Bullous changes and pulmonary cysts develop in the lung apices due to repeated episodes of inflammation and cytotoxic effects of HIV on pulmonary macrophages. These changes progress despite prophylaxis against recurrent Pneumocystis infection with aerosolized pentamidine, increasing the risk of spontaneous pneumothorax. Two cases are presented of bilateral pneumothoraces in patients with AIDS and recurrent P carinii pneumonia despite aerosolized pentamidine prophylaxis. Patients receiving aerosolized pentamidine prophylaxis for Pneumocystis pneumonia appear to have an increased risk of pneumothorax due to recurrent apical infections with P carinii.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Studies of the outer membrane proteins of Branhamella catarrhalis.

PURPOSE: Branhamella catarrhalis has emerged as an important human pathogen in the past several years. Therefore, studies of the outer membrane have been undertaken in order to identify virulence factors and begin to understand the immune response to infection. MATERIALS AND METHODS: The outer membrane of B. catarrhalis has been purified by sucrose density centrifugation. The outer membrane proteins (OMPs) of 50 strains from diverse sources were isolated by simpler methods and studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Experiments were designed to identify OMPs that express determinants on the surface of the intact bacterium. RESULTS: Eight major OMPs have been identified (OMPs A through H). The OMP patterns from diverse strains were strikingly similar. OMP E (approximately 56,000 daltons) and OMP G (approximately 28,000 daltons) have determinants that are surface-exposed and these determinants are shared among a majority of strains of B. catarrhalis. CONCLUSION: These observations have important implications with regard to the immune response to infection and future vaccine development.

Bacterial Outer Membrane Proteins↗
PubMed1990

Organ distribution of radiolabeled enteric Escherichia coli during and after hemorrhagic shock.

Translocation of intestinal bacteria to the blood during hemorrhagic shock (HS) has been confirmed in rats and humans. The current study was designed to trace the path of translocated intestinal bacteria in a murine HS model. Thirty-one rats were gavaged with 1,000,000 counts of viable 14C oleic acid-labeled Escherichia coli. Forty-eight hours later the animals were bled to 30 mmHg until either 80% of their maximal shed blood was returned or 5 hours of shock had elapsed and they were resuscitated with Ringer's lactate as previously described. Control animals were cannulated but not shocked. Eight rats immediately after shock and resuscitation, 6 rats 24 hours after shock, 3 rats 48 hours after shock, and 4 animals that died in shock had their heart, lung, liver, spleen, kidney, and serum harvested, cultured, and radioactive content measured. Translocated enteric bacteria are found primarily in the lung immediately after shock with redistribution to the liver and kidney 24 hours later. Animals surviving to 48 hours were capable of eliminating the majority of the bacteria from their major organ systems. Positive cultures for E. coli were also found in the blood, lung, liver, and kidney. We speculate that the inflammatory response stimulated by the bacteria in these organs may contribute to the multiple-organ failure syndrome seen after HS.

Animals↗
PubMed1990

A "treated" model for severe hemorrhagic shock: a comparison of conventional and germ-free animals.

In an unanesthetized "treated" model of severe hemorrhagic shock, a bacteremia originating from the animal's enteric flora was demonstrated by finding radiolabeled Escherichia coli in the blood as early as 2 hr after the onset of shock. In 50 patients admitted to our trauma unit, the observation was similar, with 56% positive blood cultures, when their mean arterial blood pressure was 80 mmHg or less. The relationship of bacterial translocation and the high post-shock mortality in our conventional (CV) animal model is being evaluated in germfree (GF) Sprague-Dawley rats. Preliminary observations in 15 GF animals showed 80% survival at 24 hr post-shock, 54% at 48 hr, and 42% at 72 hr compared with those of CV animals in previous experiments with survival at similar times of 73%, 20% and 7%, respectively.

Animals↗
PubMed1989

Non-group A streptococci in the pharynx. Pathogens or innocent bystanders?

OBJECTIVE: To determine whether beta-hemolytic streptococci from groups other than A are an important cause of sporadic pharyngitis in children. DESIGN: Cross-sectional, case-referent survey. SETTING: General pediatric clinic at a military base in Ohio. PARTICIPANTS: One hundred fifty children with symptomatic pharyngitis and 150 controls matched for age and time of presentation over a 20-month study period. INTERVENTIONS: None. MEASUREMENTS/MAIN RESULTS: Anaerobic culture technique was used to improve isolation of beta-hemolytic streptococci. Group A beta-hemolytic streptococci were detected significantly more often among the ill children than among the controls (39% vs 16%, respectively). In contrast, non-group A beta-hemolytic streptococci were isolated in similar frequency from the ill and control children (17% vs 21%, respectively). Non-group A beta-hemolytic streptococci from groups B, C, F, and G were each isolated in similar frequency among the ill and control children. The isolation rate of non-group A organisms increased with age among both patients and controls. CONCLUSIONS: Non-group A beta-hemolytic streptococci seemed not to be an important cause of sporadic pharyngitis in this pediatric population.

Adolescent↗
PubMed1989

Isolation of the outer membrane of Branhamella catarrhalis.

The emergence of Branhamella catarrhalis as an important human pathogen has stimulated interest in investigations of the outer membrane (OM) of the bacterium. In this study, the OM of B. catarrhalis was isolated and partially characterized. Radiolabelled cells were lysed and fractionated by isopycnic centrifugation in a continuous sucrose gradient. Five fractions were identified. Fraction A consisted of OM fragments of varying density. Fractions B and C were OM of a discrete density containing some cytoplasmic membrane. Fraction D was cytoplasmic membrane and Fraction E contained smaller less dense fragments of cytoplasmic membrane. The protein composition of the Branhamella OM is typical for that of Gram-negative bacteria in that approximately 10 to 20 proteins were present with six to eight of these proteins predominating. Having isolated and partially characterized the OM by sucrose density centrifugation, five simpler techniques for isolating OM were employed and the preparations compared to OM isolated on the gradient. Techniques that are based on differential detergent solubility of OM and cytoplasmic membrane were ineffective in isolating OM of B. catarrhalis. By contrast, techniques that involved collection of OM vesicles were successful in isolating OM of B. catarrhalis. Collection of vesicles from broth culture supernatants and EDTA-heat-induced vesicles were identified as convenient and reliable methods for isolating OM. Isolating and partially characterizing the OM of B. catarrhalis represents an initial step in a systematic study of outer membrane antigens of the bacterium.

Bacterial Outer Membrane Proteins↗
PubMed1989

Does the bacteremia observed in hemorrhagic shock have clinical significance? A study in germ-free animals.

We have recently reported the rapid appearance of bacteria and endotoxin in the blood of rats and of trauma patients in the course of 30 minutes to 2 hours of hemorrhagic shock. The current study was designed to determine the effect of this bacteremia and endotoxemia on survival. Thirty-three conventional (C:group 1) and 36 germ-free (GF:group 2) Sprague Dawley rats were subjected to our previously described model of treated hemorrhagic shock. Survival in the GF group was significantly better than the C group at 24, 48, and 72 hours after shock. Endotoxin levels were elevated in 88% of C group during shock and in 28% of GF group. The gut of the GF animal contains endotoxin (26 ng/gm of stool) as does the sterile food supply (393 ng/gm of rat chow).

Animals↗
PubMed1989

Surface-exposed and antigenically conserved determinants of outer membrane proteins of Branhamella catarrhalis.

The outer membrane proteins (OMPs) of Branhamella catarrhalis were studied in an effort to identify surface-exposed determinants that are conserved among strains of the bacterium. Aliquots of polyclonal antiserum were absorbed individually by strains of B. catarrhalis. The absorbed antisera were tested in comparison with unabsorbed antiserum in an immunoblot assay against OMPs of the homologous strain. The absence of a band recognized by antibodies in the absorbed antiserum compared with the unabsorbed antiserum indicated that surface-exposed determinants of the absorbing strain cross-reacted with determinants on the homologous strain. Two antisera were absorbed individually by 20 strains of B. catarrhalis, and the absorbed sera were studied in this way in immunoblot assays. OMP E (molecular weight, ca. 56,000) expresses surface-exposed determinants that are shared among 17 of the 20 strains studied. Antibodies to OMP G (molecular weight, 28,000) were absorbed from both antisera by 14 of the 20 strains. These studies demonstrate that OMP E and OMP G express determinants that are exposed on the surface of the intact bacterium. Furthermore, these determinants are antigenically conserved among a majority of strains of B. catarrhalis. On the basis of these observations, OMPs E and G should be considered when bacterial antigens are evaluated as potential vaccine candidates.

Animals↗
PubMed1989

Determination of the epidemiology and transmission of nontypable Haemophilus influenzae in children with otitis media by comparison of total genomic DNA restriction fingerprints.

It is assumed that the causative bacteria in children suffering from otitis media reach the middle ear via the eustachian tube. The purpose of this investigation was to use endonuclease restriction of bacterial chromosomal DNA to compare isolates of nontypable (NT) Haemophilus influenzae obtained from the nasopharynx and from middle ear (ME) effusions of patients with otitis media. Strains of NT H. influenzae were isolated from the nasopharynx (NP) and affected ME from a group of 13 unrelated children with otitis media with effusion (OME). For 12 of these children, identical strains were isolated from the NP and ME in a first episode of OME. Each of these 12 sets differed from the other 11. Six of these children suffered from a second episode of OME with NT H. influenzae. Five of these children with recurrence again had identical NP and ME strains. These results suggest that at the time of an episode of OME, there is one predominant strain of NT H. influenzae that colonizes both the NP and ME. The strains of NT H. influenzae isolated from all six of the second episodes were different from strains from the first episode, indicating turnover of the predominant strain in the NT H. influenzae population between episodes. When we investigated three siblings with concurrent episodes of OME, we found that they shared several similar strains of NT H. influenzae, thereby demonstrating that within a family, transmission of NT H. influenzae from child to child is possible. These results from DNA fingerprinting were essentially identical when compared with results from outer membrane protein subtyping performed on the same set of strains. The analysis of endonuclease restriction patterns of total genomic DNA provides a sensitive measure of genetic dissimilarity between strains and represents an easily applicable method for epidemiological and transmission studies of bacterial infections associated with NT H. influenzae.

Bacterial Outer Membrane Proteins↗
PubMed1989

The surface of Branhamella catarrhalis: a systematic approach to the surface antigens of an emerging pathogen.

The incidence of B. catarrhalis as a cause of otitis media is increasing. As strategies for preventing infections caused by Streptococcus pneumoniae and nontypable H. influenzae are developed, the relative importance of B. catarrhalis will increase further in the next decade. A goal of studies of surface antigens is to identify potential vaccine components. Surface antigens of B. catarrhalis include OMPs, LOS and fimbriae. Preliminary studies indicate that OMPs and LOS are relatively antigenically conserved among strains. Future investigations should be directed toward identifying conserved antigens that will generate protective antibodies.

Antigens, Surface↗
PubMed1988

Comparison of the outer membrane proteins of 50 strains of Branhamella catarrhalis.

Branhamella catarrhalis colonizes the respiratory tract of humans and commonly causes otitis media in children and respiratory infections in adults with chronic lung disease. In view of the emergence of this organism as an important human pathogen, we used sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to examine the outer membrane proteins (OMPs) of 50 strains of B. catarrhalis. OMPs were isolated from broth culture supernatants. Typical of other gram-negative bacteria, eight proteins ranging in molecular weight (MW) from approximately 98,000 to 21,000 daltons were revealed by SDS-PAGE; these proteins were designated OMP A-OMP H. Of the OMPs identified, four were heat modifiable (C, D, E, and H). The 50 strains were obtained from diverse geographic and clinical sources. The OMP patterns were strikingly homogeneous; there was minimal variability in the MW of OMPs between strains. Future studies should establish whether the similarity in MWs of OMPs is paralleled by their antigenic characteristics.

Bacterial Outer Membrane Proteins↗
PubMed1988

Endotoxemia and bacteremia during hemorrhagic shock. The link between trauma and sepsis?

Previous investigations of a treated model of hemorrhagic shock in the rat indicated the frequent occurrence of bacteremia that appeared to derive from the gut. This paper determines the incidence of bacteremia and endotoxemia during the acute shock period and compares this with similar observations in humans in varying degrees of shock. Studies in 26 rats indicated that bacteremia and endotoxemia was present in 50% and 87%, respectively, by the end of 2 hours at a mean arterial pressure of 30 mmHg. Observations in 50 patients admitted to the trauma unit showed that positive bacterial blood cultures were present in 56% when the admission systolic blood pressure was 80 mmHg or less (p less than 0.01 compared with either of the other groups). Endotoxemia was noticed in two such patients. Direct access of bacteria and endotoxin to the blood stream may occur during hemorrhagic or traumatic shock and is the probable cause of subsequent sepsis in traumatized patients when no other source is apparent.

Acute Disease↗
PubMed1988

Cloning and sequencing of Haemophilus influenzae outer membrane protein P6.

P6, a 16,600-dalton protein present in the outer membranes of both typeable and nontypeable strains, may be an important antigen in immunity to Haemophilus influenzae. The gene encoding P6 of a nontypeable strain of H. influenzae was cloned by using bacteriophage lambda gt11. Four recombinant phages were detected by screening plaques with monoclonal antibodies and a polyclonal antiserum. One recombinant phage, clone O, produced a full-length gene product which was expressed at a high yield. The DNA insert contained within this phage was cloned into the plasmid vector pUC18 to create the recombinant plasmid pBUD1. An Escherichia coli transformant containing this plasmid produced a protein which had an apparent molecular weight identical to that of H. influenzae P6, as determined by Western blot (immunoblot) analyses. Expression of the P6 polypeptide by both clone 0 and the transformant was independent of induction of the lac operon by isopropyl-beta-D-thiogalactopyranoside, suggesting that transcription was from the promoter of the P6 gene. Immunoelectron microscopy using a monoclonal antibody with specificity for a P6 surface epitope detected the presence of P6 on the surface of the transformant. The insert in pBUD1 was cut down in size to approximately 800 base pairs. The resultant plasmid, pBUD5, also coded for a full-length gene product. DNA sequence analysis revealed that the P6 gene contains transcriptional and translational sequences resembling those recognized in E. coli and a signal sequence characteristic of procaryotic membrane proteins. In addition, the carboxy terminus of this signal sequence shares homology with a common sequence found in bacterial lipoproteins, suggesting that P6 is a lipoprotein. Posttranslational proteolytic cleavage of the signal sequence would result in a protein composed of 134 amino acids.

Amino Acid Sequence↗
PubMed1988

Human bactericidal antibody response to outer membrane protein P2 of nontypeable Haemophilus influenzae.

The human bactericidal antibody response to the major outer membrane protein, P2, of nontypeable Haemophilus influenzae was studied. P2 was isolated from two strains of nontypeable H. influenzae and coupled to affinity columns. Pooled normal human serum was subjected to affinity chromatography with the P2 columns and a control column. Reducing the titer of antibody to P2 resulted in reduced bactericidal activity of that serum for the organism. Immunopurified antibody to P2 from human serum was bactericidal for the homologous strain. The extent to which these bactericidal determinants on P2 are conserved among strains was investigated. Immunopurified antibodies to P2 of two epidemiologically unrelated isolates were bactericidal for four of six strains tested. We conclude that P2 is a target for human bactericidal antibody and that some of these determinants that are recognized by human bactericidal antibody are conserved among strains of nontypeable H. influenzae.

Antibodies, Bacterial↗