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Biomedical subjects

E J O'Rourke

Publications and source records attributed to E J O'Rourke.

At least 19 recordsLinked to original sources
PubMed2000

A novel 3-methyladenine DNA glycosylase from Helicobacter pylori defines a new class within the endonuclease III family of base excision repair glycosylases.

The cloning, purification, and characterization of MagIII, a 3-methyladenine DNA glycosylase from Helicobacter pylori, is presented in this paper. Sequence analysis of the genome of this pathogen failed to identify open reading frames potentially coding for proteins with a 3-methyladenine DNA glycosylase activity. The putative product of the HP602 open reading frame, reported as an endonuclease III, shares extensive amino acid sequence homology with some bacterial members of this family and has the canonic active site helix-hairpin-helix-GPD motif. Surprisingly, this predicted H. pylori endonuclease III encodes a 25,220-Da protein able to release 3-methyladenine, but not oxidized bases, from modified DNA. MagIII has no abasic site lyase activity and displays the substrate specificity of the 3-methyladenine-DNA glycosylase type I of Escherichia coli (Tag) because it is not able to recognize 7-methylguanine or hypoxanthine as substrates. The expression of the magIII open reading frame in null 3-methyladenine glycosylase E. coli (tag alkA) restores to this mutant partial resistance to alkylating agents. MagIII-deficient H. pylori cells show an alkylation-sensitive phenotype. H. pylori wild type cells exposed to alkylating agents present an adaptive response by inducing the expression of magIII. MagIII is thus a novel bacterial member of the endonuclease III family, which displays biochemical properties not described for any of the members of this group until now.

Amino Acid Motifs↗
PubMed2000

Perforated appendicitis: prospective outcome analysis for 150 children.

BACKGROUND/PURPOSE: Controversy persists in the management of perforated appendicitis with regard to antibiotic choice and duration, operative timing, drain utilization, and wound closure. For 2 decades at the authors' institution, patients were treated with ampicillin, gentamicin, and clindamycin for 10 inpatient days, with drains in the abdomen, resulting in lower complication rates than most other published series. Managed care pressures have led to less aggressive medical management regimens with length of stay and financial factors viewed as principal outcome measures with little emphasis on clinical outcomes. In addition, there are little prospective data on clinical outcomes. The authors sought to determine whether our previously documented excellent quality outcomes could be maintained when modifications aimed at decreasing cost and length of stay in our protocol were instituted. METHODS: The authors monitored prospectively clinical outcomes in patients with perforated appendicitis treated according to their clinical practice guidelines over a 43-month period. Patients received a single antibiotic, piperacillin-tazobactam, intravenously for 10 days. They were permitted to go home with a percutaneous intravenous catheter for the final 5 days if medical and social criteria were met. Other practices from our earlier protocol were continued, including immediate operation, placement of Penrose drains, and primary wound closure. RESULTS: Of 150 patients treated on our protocol, major complications included intraabdominal abscess in 5 (3.3%), cecal fistula in 2 (1.3%), phlegmon in 3 (2.0%), wound infection in 4 (2.7%), and no small bowel obstructions requiring operation. None of these complications, nor their aggregate, were significantly more common than those reported in 373 patients treated over 11 years on the authors' prior protocol (chi2, P > .05). CONCLUSIONS: Prospective outcome analysis of our protocol shows that a single broad-spectrum antibiotic (allowing portions of therapy to be delivered less expensively on an outpatient basis) effectively can treat postoperative appendicitis with very few infectious complications. These outcome data provide baseline against which future protocols can be compared. All treatment modifications aimed at decreasing costs must be analyzed to ensure quality of care is not unduly compromised.

Adolescent↗
PubMed1998

Hospital infection prevention and control: a model for improving the quality of hospital care in low- and middle-income countries.

Continuous quality improvement (CQI) is a powerful methodology for improving clinical outcomes and patient satisfaction while reducing inefficiency and costs. However, most hospitals in low- and middle-income countries have little experience with CQI methods. Hospital infection prevention is an ideal model for nascent efforts to improve the quality of hospital care because of its proven efficacy in reducing the occurrence of infections that compromise patient outcomes and increase costs. This article describes the design and implementation of a demonstration project to reduce the incidence of surgical-site infections (SSIs) for hospitals with little experience with quality-improvement methods. The project has a high likelihood of producing measurable reductions in SSI rates and hospital costs related to inefficient use of perioperative antimicrobial prophylaxis. Moreover, participating staff will gain experience that can be applied to efforts to improve the quality of other aspects of hospital care.

Developing Countries↗
PubMed1992

Outpatient treatment of febrile infants 28 to 89 days of age with intramuscular administration of ceftriaxone.

STUDY OBJECTIVE: To determine the outcome of outpatient treatment of febrile infants 28 to 89 days of age with intramuscular administration of ceftriaxone. DESIGN: Prospective consecutive cohort study. SETTING: Urban emergency department. PATIENTS: Five hundred three infants 28 to 89 days of age with temperatures greater than or equal to 38 degrees C who did not appear ill, had no source of fever detected on physical examination, had a peripheral leukocyte count less than 20 x 10(9) cells/L, had a cerebrospinal fluid leukocyte count less than 10 x 10(6)/L, did not have measurable urinary leukocyte esterase, and had a caretaker available by telephone. Follow-up was obtained for all but one patient (99.8%). INTERVENTION: After blood, urine, and cerebrospinal fluid cultures had been obtained, the infants received 50 mg/kg intramuscularly administered ceftriaxone and were discharged home. The infants returned for evaluation and further intramuscular administration of ceftriaxone 24 hours later; telephone follow-up was conducted 2 and 7 days later. RESULTS: Twenty-seven patients (5.4%) had a serious bacterial infection identified during follow-up; 476 (94.6%) did not. Of the 27 infants with serious bacterial infections, 9 (1.8%) had bacteremia (8 of these had occult bacteremia and 1 had bacteremia with a urinary tract infection), 8 (1.6%) had urinary tract infections without bacteremia, and 10 (2.0%) had bacterial gastroenteritis without bacteremia. Clinical screening criteria did not enable discrimination between infants with and those without serious bacterial infections. All infants with serious bacterial infections received an appropriate course of antimicrobial therapy and were well at follow-up. One infant had osteomyelitis diagnosed 1 week after entry into the study, received an appropriate course of intravenous antimicrobial therapy, and recovered fully. CONCLUSIONS: After a full evaluation for sepsis, outpatient treatment of febrile infants with intramuscular administration of ceftriaxone pending culture results and adherence to a strict follow-up protocol is a successful alternative to hospital admission.

Ambulatory Care↗
PubMed1992

Osteomyelitis in children: gadolinium-enhanced MR imaging.

Fifteen pediatric patients with biopsy- or culture-proved nonspinal osteomyelitis were studied with magnetic resonance (MR) imaging. Osteomyelitis was acute in seven patients, subacute in three, and chronic in five. Four patients had subperiosteal abscesses, one had a large associated soft-tissue abscess, and one had an intraosseous (Brodie) abscess. Areas of active inflammation had decreased marrow signal intensity on T1-weighted images, increased signal intensity on T2-weighted images, and enhancement on T1-weighted images obtained after gadopentetate dimeglumine administration (n = 10). Abscesses were rim enhancing (n = 3) or not (n = 2) with gadolinium-enhanced MR imaging. Nonenhancing areas presumably represented necrotic material. Gadolinium-enhanced MR imaging assisted in definition of the presence and extent of nonvascularized fluid collections within the bone and/or adjacent soft tissues and the extent of bone involvement in patients with chronic osteomyelitis. It also helped guide surgical debridement of intraosseous disease (n = 7) and open or percutaneous drainage of subperiosteal or soft-tissue fluid collections (n = 5).

Abscess↗
PubMed1991

Adaptation of the Centers for Disease Control guidelines for the prevention of nosocomial infection in a pediatric intensive care unit in Jakarta, Indonesia.

We attempted to implement a nosocomial infection control program based on the Centers for Disease Control (CDC) guidelines in an urban Indonesian public hospital at the request of Project Hope. Adoption of unmodified CDC guidelines was impeded by a substandard physical plant, absence of an infection control infrastructure, limited sterilization capabilities, lack of clinical microbiologic laboratory support, and the expense of single use medical devices. After on-site evaluations, CDC guidelines were extensively modified so that they were appropriate for local conditions and culture. Strategies included inexpensive architectural modifications, addition of sinks and a commode, introduction of disinfection procedures for reuse of disposable medical devices, and adaptation of available supplies for maintenance of aseptic technique. On subsequent site visits, many physical changes had been accomplished, and handling of reusable and disposable medical devises had improved considerably but adoption of clinical practice policies was incomplete. We conclude that it may be difficult to implement and sustain improvements in clinical practice in the absence of an infection control infrastructure and a strong commitment by hospital clinicians and administrators. Additional research is needed to refine flexible methods for rapidly assessing the specific infection control needs of institutions with widely disparate resources, patient populations, environments, and cultures.

Centers for Disease Control and Prevention, U.S.↗
PubMed1991

False resistance to imipenem with a microdilution susceptibility testing system.

Routine monitoring of antibiotic resistance at Children's Hospital, Boston, detected a dramatic increase in the prevalence of imipenem-resistant strains of Pseudomonas aeruginosa. Further studies documented that false resistance to imipenem was due, in part, to the loss of imipenem potency in customized MIC microdilution trays supplied by Sensititre Ltd. (West Sussex, United Kingdom). Recognition of the problem was delayed by use of the quality control standard recommended by the manufacturer, which were higher and broader than those suggested by the National Committee for Clinical Laboratory Standards.

Cystic Fibrosis↗
PubMed1990

Scedosporium inflatum: clinical spectrum of a newly recognized pathogen.

The clinical course of 11 patients is reported: a newly-described species, Scedosporium inflatum, was isolated from each. Infections were primarily focally invasive and involved musculoskeletal tissues. All but one followed penetrating trauma, often minor, or surgery. Two cases, one fatal, occurred in immunosuppressed patients. In only one case was there presumptive hematogenous spread. In three cases colonization with S. inflatum could not reliably be distinguished from infection. In vitro susceptibility testing of isolates from all patients showed that all were resistant to amphotericin B, miconazole, and ketoconazole and most were resistant to fluconazole and itraconazole. The optimum management of S. inflatum infection is not apparent: Although several patients recovered without antifungal therapy, progressive unremitting infection occurred in an immunocompromised patient and in a previously healthy child despite aggressive antifungal chemotherapy and surgical debridement.

Adult↗
PubMed1989

Genetic relatedness among structural protein genes of dengue 1 virus strains.

The structural protein-coding genomic regions of dengue virus type 1 (DEN-1) strains representing three distinct topotypes (Thailand, Philippines and Caribbean) were cloned and sequenced. In addition the envelope (E) nucleotide sequences of two recent Caribbean topotype DEN-1 isolates were obtained by direct RNA sequencing. The nucleotide sequence of the DEN-1 viruses in the structural gene region was found to be highly conserved with greater than 95% nucleotide sequence homology and with less than 4% change in the amino acid sequence. Although there was a less than 2% change in the nucleotide sequence of DEN-1 E proteins, strains could be differentiated by the clusters of nucleotide changes. Furthermore, the deduced amino acid changes in the E protein were clustered primarily within the proposed immunologically reactive regions. Genomic nucleotide sequence comparisons did not define geographical or virulence markers but located unique clusters of nucleotide/amino acid changes for each of the three topotypes of DEN-1 viruses examined.

Amino Acid Sequence↗
PubMed1987

Effects of transport inhibitors on the generation and transport of a soluble viral glycoprotein.

The generation and transport of the soluble glycoprotein (Gs) of wild-type vesicular stomatitis virus (VSV) were studied using cell fractionation and transport inhibitors. Gs was found in the rough endoplasmic reticulum (RER) and the Golgi-enriched membrane fractions of infected Chinese hamster ovary cells. The identity of intracellular Gs was confirmed by its precipitation with a monoclonal antibody to the ectodomain but not with a anti-peptide antibody directed against the first 15 amino acids at the carboxy terminus of the VSV transmembrane glycoprotein G. Their extracellular appearance was affected in a concentration-dependent manner by monensin and carbonyl cyanide m-chlorophenylhydrazone (CCCP) and was completely inhibited by incubation at 20 degrees. Inhibitors failed to dissociate the transport of Gs from G. These experiments indicate that in fibroblast cells Gs can be generated intracellularly, probably in the RER, and that Gs, like G, is transported from there to the Golgi complex and then presumably to the extracellular environment.

Animals↗
PubMed1987

Impact of rapid antigen tests for group A streptococcal pharyngitis on physician use of antibiotics and throat cultures.

Using case scenarios and an interview guided by a decision tree diagram, the clinical strategies of 150 physicians (50 private pediatricians, 50 health maintenance organization pediatricians and 50 pediatric residents) were assessed for the management of pharyngitis under three conditions: (1) no rapid antigen detection test available for diagnosing Group A streptococcal disease; (2) antigen test result available in 20 minutes; and (3) antigen test result available in 4 hours. The sensitivity of the antigen test was designated as 0.95 if the growth of rare or few Group A streptococci on throat culture was discounted and 0.82 if any growth was considered significant, and the specificity was set at 0.98. In a standardized pediatric case with a prior probability of Group A streptococcal disease of 0.58, 84% of clinicians would order a 20-minute test and 39% would order a 4-hour test. The 20-minute test would reduce throat culture use by 54%, reduce the proportion of patients exposed to antibiotics from 86% to 65% and reduce total antibiotic treatment days by 13.8%. Effects would be less pronounced for a low probability case or if results of antigen testing were not available for 4 hours. Provided a test with a documented high sensitivity and specificity were used, a rapid antigen test with results promptly available would substantially reduce throat culture use and unnecessary antibiotic exposures in children with a moderate prior probability of streptococcal disease.

Anti-Bacterial Agents↗
PubMed1983

Antibody-induced modulation of proteins in vesicular stomatitis virus-infected fibroblasts.

When vesicular stomatitis virus-infected baby hamster kidney cells were treated with rabbit anti-vesicular stomatitis virus serum, there was a loss of the viral glycoprotein G into acid-soluble products. This degradation occurred within minutes at 37 degrees C and required the presence of G protein at the cell surface. The degree of degradation depended on antiserum concentration. The antiserum, also, prevented maturation of extracellular virions and induced partial degradation of the intracellular viral proteins, without affecting host proteins. The degradation could not be prevented by the presence of lysosomotropic agents, protease inhibitors, colchicine, or cytochalasin B. Similar kinetics and specificity of degradation was obtained with cells infected with vesicular stomatitis virus mutants that were less cytopathic. These results characterize a model system for studying the parameters and consequences of antigenic modulation as well as for studying the fate of viral antigens during persistent infections.

Animals↗
PubMed1980

Enhancement of dengue virus infection in monocytes by flavivirus antisera.

Enhanced dengue 2 virus (D2V) infection in suspension cultures of human peripheral blood mononuclear phagocytes (PBL) produced by subneutralizing concentrations of dengue antisera has been described previously. In this study, the enhancement phenomenon was found to be a general property of representative flavivirus antisera. All except one of 24 antisera, which had been raised by 1-3 injections of flaviviruses in rabbits, enhanced the growth of dengue 2 virus in human PBL. Flavivirus antisera showing the greatest level of cross-reactivity against a battery of 42 flavivirus antigens in the hemagglutination-inhibition test were most potent in enhancing dengue replication in PBL cultures. Cross-neutralizing reactivity did not relate to enhanced D2V infection. However nearly one-half of studied flavivirus antisera neutralized D2V at dilutions of 1:10 or 1:20. Heterotypic D2V neutralizing antibody could serve as a "brake" on infection enhancement in vivo. Observations should be made in the field to look for possible enhancement of dengue infection in heterotypic flavivirus immunes.

Adult↗