PubMed Health⌕ Search

Biomedical subjects

E S Wong

Publications and source records attributed to E S Wong.

At least 19 recordsLinked to original sources
PubMed2000

Evidence for direct interaction between Sprouty and Cbl.

Sprouty (SPRY) was first identified in a genetic screen in Drosophila as an antagonist of fibroblast and epidermal growth factor receptors and Sevenless signaling, seemingly by inhibiting the receptor tyrosine kinase (RTK)/Ras/MAPK pathway. To date, four mammalian Sprouty genes have been identified; the primary sequences of the gene products share a well conserved cysteine-rich C-terminal domain with their Drosophila counterpart. The N-terminal regions do not, however, exhibit a large degree of homology. This study was aimed at identifying proteins with which human SPRY2 (hSPRY2) interacts in an attempt to understand the mechanism by which Sprouty proteins exert their down-regulatory effects. Here, we demonstrate that hSPRY2 associates directly with c-Cbl, a known down-regulator of RTK signaling. A short sequence in the N terminus of hSPRY2 was found to bind directly to the Ring finger domain of c-Cbl. Parallel binding was apparent between the Drosophila homologs of Sprouty and Cbl, with cross-species associations occurring at least in vitro. Coexpression of hSPRY2 abrogated an increase in the rate of epidermal growth factor receptor internalization induced by c-Cbl, whereas a mutant hSPRY2 protein unable to bind c-Cbl showed no such effect. Our results suggest that one function of hSPRY2 in signaling processes downstream of RTKs may be to modulate c-Cbl physiological function such as that seen with receptor-mediated endocytosis.

Amino Acid Sequence↗
PubMed2000

Sprouty proteins are targeted to membrane ruffles upon growth factor receptor tyrosine kinase activation. Identification of a novel translocation domain.

Sprouty (Spry) was first identified in a genetic screen in Drosophila to be an antagonist of fibroblast growth factor and epidermal growth factor (EGF) signaling, seemingly by inhibiting the Ras/MAP kinase pathway. Data base searches lead to the identification and cloning of, to date, four mammalian sprouty genes. The primary sequences of the mammalian sprouty gene products share a well conserved cysteine-rich C-terminal domain with the Drosophila protein. The N-terminal regions, however, do not exhibit significant homology. This study aimed at determining the disposition of Spry proteins in intact cells before and after stimulation of the EGF receptor tyrosine kinase. Full-length or deletion mutants of Spry, tagged at the N termini with the FLAG-epitope, were expressed in COS-1 cells by transient transfection and analyzed by immunofluorescence microscopy before and after EGF stimulation of the cells. In unstimulated cells, the Spry proteins were distributed throughout the cytosol except for human Sprouty2 (hSpry2), which, although generally located in the cytosol, co-localized with microtubules. In all cases, the Spry proteins underwent rapid translocation to membrane ruffles following EGF stimulation. The optimal translocation domain was identified by deletion and immunofluorescence analysis to be a highly conserved 105-amino acid domain in the C-terminal half of the hSpry2 protein. The translocation of this conserved domain, based on hSpry2 data, was independent of the activation of phosphatidylinositol-3 kinase.

Amino Acid Sequence↗
PubMed1999

Tyrosine phosphorylation of the Bcl-2-associated protein BNIP-2 by fibroblast growth factor receptor-1 prevents its binding to Cdc42GAP and Cdc42.

Fibroblast growth factor (FGF) receptor tyrosine kinases are involved in the regulation of cell growth, development, and differentiation in a variety of tissues. To isolate potential signaling molecules in the FGF signaling pathway, we have initiated a yeast two-hybrid screening using the cytosolic domain of FGF receptor-1 (Flg). Here we report the identification of BNIP-2, a previously cloned Bcl-2- and adenovirus E1B-associated protein, as a putative substrate of the receptor. When cotransfected in 293T cells, BNIP-2 was tyrosine-phosphorylated via Flg, but their interaction was transient and could only be seen by "capture" experiments with catalytically inert kinase mutants. When responsive cells were challenged with basic FGF, endogenous tyrosine-phosphorylated BNIP-2 could be precipitated with a BNIP-2 antibody. In addition, the recombinant BNIP-2 expressed in bacteria could be phosphorylated by active Flg in vitro. BNIP-2 shares a region of homology with the noncatalytic domain of Cdc42GAP, a GTPase-activating protein for the small GTP-binding molecule, Cdc42. We show here that BNIP-2 and Cdc42GAP could directly bind to each other and they also compete for the binding to the same target, Cdc42. Unexpectedly, BNIP-2, either produced as a bacterial recombinant protein or expressed in 293T cells, could stimulate the intrinsic GTPase activity of Cdc42. In all cases, tyrosine phosphorylation of BNIP-2 severely impaired its association with Cdc42GAP and its induced GTPase-activating protein-like activity toward Cdc42. These findings should allow us to further characterize the integration of signaling between receptor tyrosine kinases, GTP-binding molecules, and apoptotic pathways.

Amino Acid Sequence↗
PubMed1999

Association of atypical protein kinase C isotypes with the docker protein FRS2 in fibroblast growth factor signaling.

FRS2 is a docker protein that recruits signaling proteins to the plasma membrane in fibroblast growth factor signal transduction. We report here that FRS2 was associated with PKC lambda when Swiss 3T3 cells were stimulated with basic fibroblast growth factor. PKC zeta, the other member of the atypical PKC subfamily, could also bind FRS2. The association between FRS2 and PKC lambda is likely to be direct as shown by yeast two-hybrid analysis. The C-terminal fragments of FRS2 (amino acid residues 300-508) and SNT2 (amino acids 281-492), an isoform bearing 50% identity to FRS2, interacted with PKC lambda at a region (amino acids 240-562) that encompasses the catalytic domain. In vitro kinase assays revealed neither FRS2 nor SNT2 was a substrate of PKC lambda or zeta. Mutation of the alanine residue (Ala-120) to glutamate in the pseudo-substrate region of PKC lambda results in a constitutively active kinase that exhibited more than 2-fold greater binding to FRS2 in vitro than its "closed" wild-type counterpart. Tyrosine phosphorylation of FRS2 did not affect its binding to the constitutively active PKC lambda mutant, suggesting that the activation of PKC lambda is necessary and sufficient for its association with FRS2. It is likely that FRS2 serves as an anchoring protein for targeting activated atypical PKCs to the cell plasma membrane in signaling pathways.

3T3 Cells↗
PubMed1999

Urinary tract infections in adults.

Urinary tract infections remain a significant cause of morbidity in all age groups. Recent studies have helped to better define the population groups at risk for these infections, as well as the most cost-effective management strategies. Initially, a urinary tract infection should be categorized as complicated or uncomplicated. Further categorization of the infection by clinical syndrome and by host (i.e., acute cystitis in young women, acute pyelonephritis, catheter-related infection, infection in men, asymptomatic bacteriuria in the elderly) helps the physician determine the appropriate diagnostic and management strategies. Uncomplicated urinary tract infections are caused by a predictable group of susceptible organisms. These infections can be empirically treated without the need for urine cultures. The most effective therapy for an uncomplicated infection is a three-day course of trimethoprim-sulfamethoxazole. Complicated infections are diagnosed by quantitative urine cultures and require a more prolonged course of therapy. Asymptomatic bacteriuria rarely requires treatment and is not associated with increased morbidity in elderly patients.

Adult↗
PubMed1998

Hospital-wide restriction of clindamycin: effect on the incidence of Clostridium difficile-associated diarrhea and cost.

BACKGROUND: Widespread antibiotic use has been associated with increases in both bacterial resistance and nosocomial infection. OBJECTIVE: To characterize the impact of hospital-wide clindamycin restriction on the incidence of Clostridium difficile-associated diarrhea and on antimicrobial prescribing practices. DESIGN: Prospective, observational cohort study. SETTING: University-affiliated Veterans Affairs Medical Center. PATIENTS: Hospitalized patients with symptomatic diarrhea. MEASUREMENTS: Clinical data on individual patients and data on antibiotic use were obtained from hospital pharmacy records. Hospital-wide use of antimicrobial agents was monitored. Isolates of C. difficile underwent antimicrobial susceptibility testing and molecular typing. RESULTS: An outbreak of C. difficile-associated diarrhea was caused by a clonal isolate of clindamycin-resistant C. difficile and was associated with increased use of clindamycin. Hospital-wide requirement of approval by an infectious disease consultant of clindamycin use led to an overall reduction in clindamycin use, a sustained reduction in the mean number of cases of C. difficile-associated diarrhea (11.5 cases/month compared with 3.33 cases/month; P < 0.001), and an increase in clindamycin susceptibility among C. difficile isolates (9% compared with 61%; P < 0.001). A parallel increase was noted in the use of and costs associated with other antibiotics with antianaerobic activity, including cefotetan, ticarcillin-clavulanate, and imipenem-cilastin. The hospital realized overall cost savings as a result of the decreased incidence of C. difficile-associated diarrhea. CONCLUSIONS: Hospital formulary restriction of clindamycin is an effective way to decrease the number of infections due to C. difficile. It can also lead to a return in clindamycin susceptibility among isolates and can effect cost savings to the hospital.

Anti-Bacterial Agents↗
PubMed1997

An outbreak of Pseudomonas aeruginosa related to contaminated urodynamic equipment.

Investigation of an outbreak of multiresistant Pseudomonas aeruginosa urinary tract infections within our hospital identified the urodynamic laboratory as the point source. Disinfection procedures were inadequate, and transducers designated for single-patient use were used repeatedly and subsequently became contaminated. These improper procedures were part of a cost-containment effort.

Cross Infection↗
PubMed1996

The effect of respirator training on the ability of healthcare workers to pass a qualitative fit test.

OBJECTIVES: To determine the effect of different methods of training on the ability of hospital workers to wear respirators and pass a qualitative fit test, and to compare the direct cost of the training. DESIGN: 179 hospital employees were recruited for study and were stratified into three groups based on the type of training they received in the use of respirators. Employees in Group A received one-on-one training by the hospital's industrial hygienist and were fit tested as part of this training. Employees in Group B received classroom instruction and demonstration by infection control nurses in the proper use of respirators, but were not fit tested as part of training. Employees in Group C received no formal training. Each participant in our study underwent a subsequent qualitative fit test using irritant smoke to check for the employee's ability to adjust correctly the fit and seal of the respirator. The direct cost of each method of training was determined by accounting for the cost of trainers and the cost of employee-hours lost during training. SETTING: 775-bed Veterans' Affairs hospital. RESULTS: 94% of Group A participants (49 of 52) passed the qualitative fit test, compared to 91% of Group B participants (58 of 64) and 79% of Group C participants (50 of 63; P = .036, 2 x 3 chi-square). Group A had a significantly higher pass rate than Group C (P = .043), but Group B did not differ significantly from Group A or Group C. Location or professional status did not affect pass rate, but prior experience wearing respirators did. When the study groups were compared after stratifying for prior experience, we found no difference in pass rates, except when Groups A and B (those with any training) were combined and compared with Group C (107 of 116 versus 50 of 63, P = .05, Mantel-Haenszel chi-square). We estimate that the method of training involving individual instruction followed by fit testing took 20 minutes per employee to complete, compared to 10 minutes per six employee class for the method of classroom demonstration. The difference in direct cost between the two methods, applied to the training of 1,200 employees at our hospital, would be approximately $19,000 per year. CONCLUSION: Our study indicates that training in the proper use of respirators is important, but the method of training may not be, as the two methods we evaluated were nearly equivalent in their pass rates on fit testing (94% versus 91%). Fit testing as part of training may have enhanced the performance of our participants marginally, but was more time consuming and accounted for most of the excess cost.

Chi-Square Distribution↗
PubMed1995

Do protective devices prevent needlestick injuries among health care workers?

OBJECTIVES: To determine the effectiveness and direct of two protective devices-a shielded 3 ml safety syringe (Safety-Lok; Becton Dickinson and Co., Becton Dickinson Division, Franklin Lakes, N.J.) and the components of a needleless IV system (InterLink; Baxter Healthcare Corp., Deerfield, Ill.)--in preventing needlestick injuries to health care workers. DESIGN: Twelve-month prospective, controlled, before-and-after trial with a standardized questionnaire to monitor needlestick injury rates. SETTING: Six hospital inpatient units, consisting of three medical units, two surgical units (all of which were similar in patient census, acuity, and frequency of needlesticks), and a surgical-trauma intensive care unit, at a 900-bed urban university medical center. PARTICIPANTS: All nursing personnel, including registered nurses, licensed practical nurses, nursing aides, and students, as well as medical teams consisting of an attending physician, resident physician, interns, and medical students on the study units. INTERVENTION: After a 6-month prospective surveillance period, the protective devices were randomly introduced to four of the chosen study units and to the surgical-trauma intensive care unit. RESULTS: Forty-seven needlesticks were reported throughout the entire study period, 33 in the 6 months before and 14 in the 6 months after the introduction of the protective devices. Nursing staff members who were using hollow-bore needles and manipulating intravenous lines accounted for the greatest number of needlestick injuries in the pre-intervention period. The overall rate of needlestick injury was reduced by 61%, from 0.785 to 0.303 needlestick injuries per 1000 health care worker-days after the introduction of the protective devices (relative risk = 1.958; 95% confidence interval, 1.012 to 3.790; p = 0.046). Needlestick injury rates associated with intravenous line manipulation, procedures with 3 ml syringes, and sharps disposal were reduced by 50%; however, reductions in these subcategories were not statistically significant. No seroconversions to HIV-1 or hepatitis B virus seropositivity occurred among those with needlestick injuries. The direct cost for each needlestick prevented was $789. CONCLUSIONS: Despite an overall reduction in needlestick injury rates, no statistically significant reductions could be directly attributed to the protective devices. These devices are associated with a significant increase in cost compared with conventional devices. Further studies must be concurrently controlled to establish the effectiveness of these devices.

Direct Service Costs↗
PubMed1994

Prosthetic valve endocarditis: superiority of surgical valve replacement versus medical therapy only.

The objective of our study was to assess the long-term outcome of patients with prosthetic valve endocarditis. We used a multicenter, prospective, observational study design. Six university teaching hospitals with high volume cardiothoracic surgery participated. Seventy-four patients with prosthetic valve endocarditis as defined by explicit, objective criteria were selected for participation. All patients were followed up prospectively for 1 year. Thirty-one percent and 69% had development of endocarditis within 60 days of valve insertion ("early") and after 60 days ("late"), respectively. The most common causes were Staphylococcus epidermidis (40%), Staphylococcus aureus (20%), streptococcal species (18%), and aerobic gram-negative bacilli (11%). Physical signs of endocarditis (new or changing murmur, stigmata, emboli) were seen in 58%. At 6 months and 12 months, mortality was 46% and 47%, respectively. Surgical replacement of the infected valve led to significantly lower mortality (23%) as compared with medical therapy alone (56%), as assessed by both univariate and multivariate analyses (p < 0.05). Improved outcome was seen for the surgical group even when controlling for severity of illness at time of diagnosis. From these findings we conclude that accurate assessment of outcome in prosthetic valve endocarditis requires long-term follow-up of at least 6 months following diagnosis. Surgical therapy warrants greater scrutiny; evaluation in controlled clinical trials is appropriate.

Adult↗
PubMed1994

Prostatic fluid analysis in spinal-cord-injured patients with recurrent urinary tract infections.

OBJECTIVE: Recurrent urinary tract infections are common in spinal-cord-injured patients. Our study was designed to evaluate the association of bacteria colony counts, white blood cell (WBC) count, and antibody-coated bacteria analyzed in urethral and prostatic samples in hospitalized spinal-cord-injured patients with recurrent urinary tract infections. METHODS: Thirty-three patients were studied and 4 noninfected patients served as controls; 17 patients were paraplegic and 20 were quadriplegic. Mean patient age was 34.8 years and mean follow-up period was ninety-three days. During the surveillance period, 19 of the 33 patients had relapsing infections (same organism), while 14 had reinfections (new organism). A modified Foley catheter was used to seal the bladder neck, so that urethral and prostatic samples could be obtained. RESULTS: Bacteria colony counts and WBC counts did not correlate with relapsing infection. However, significantly more patients with relapsing infection (8/19) had antibody-coated bacteria in their prostatic fluid than patients with reinfection (1/13) (P < 0.05). CONCLUSIONS: The presence of antibody-coated bacteria in prostatic fluid is associated with relapsing urinary tract infections and not with reinfection.

Adult↗
PubMed1993

Prosthetic valve endocarditis resulting from nosocomial bacteremia. A prospective, multicenter study.

OBJECTIVE: To determine the incidence of endocarditis in bacteremic patients with prosthetic heart valves and the risk factors for and the effect of duration of antibiotic therapy on development of endocarditis in such patients. DESIGN: Multicenter, prospective observational study. SETTING: Six university teaching hospitals with high-volume cardiothoracic surgery. PARTICIPANTS: One hundred seventy-one consecutive patients with prosthetic heart valves who developed bacteremia during hospitalization. MEASUREMENTS AND MAIN RESULTS: Patients were evaluated when they were identified as having bacteremia and 1, 2, 6, and 12 months after its occurrence. Of 171 patients, 74 (43%) developed endocarditis: Fifty-six (33%) had prosthetic valve endocarditis at the time bacteremia was discovered ("endocarditis at outset"), whereas 18 (11%) developed endocarditis a mean of 45 days after bacteremia was discovered ("new endocarditis"). Mitral valve location and staphylococcal bacteremia (Staphylococcus aureus or S. epidermidis) were significantly associated with the development of "new" endocarditis. All 18 cases of new endocarditis were nosocomial, and in 6 of these cases (33%) bacteremia was acquired via intravascular devices. Twenty-one patients without evidence of endocarditis at the time of bacteremia received short-term antibiotic therapy (< 14 days); 1 patient (5%) developed endocarditis. Eleven of 70 patients (16%) who received long-term antibiotic therapy (> 14 days) developed endocarditis (P > 0.2). CONCLUSIONS: Bacteremic patients with prosthetic heart valves were at notable risk for developing endocarditis, even when they received antibiotic therapy before endocarditis developed and regardless of the duration of such therapy. Intravascular devices were a common portal of entry.

Adult↗
PubMed1993

Comparison of ampicillin-sulbactam with vancomycin for treatment of experimental endocarditis due to a beta-lactamase-producing, highly gentamicin-resistant isolate of Enterococcus faecalis.

Increasing antibiotic resistance in the enterococci, including the capacity for beta-lactamase production and the development of high-level aminoglycoside resistance, has complicated the treatment of serious enterococcal infections, which often require synergistic antibiotic combinations for cure. We utilized the rabbit model of aortic valve endocarditis to investigate the effects of various antibiotics, alone and in combination, against a multiply antibiotic-resistant isolate of Enterococcus faecalis. Female New Zealand White rabbits were infected with either a beta-lactamase-producing, gentamicin-resistant isolate of E. faecalis or a non-beta-lactamase-producing, aminoglycoside-susceptible isolate, and the mean log10 CFU per gram of vegetation were determined. The most active agents were low-dose ampicillin-sulbactam (200 mg/kg of body weight per day), high-dose ampicillin-sulbactam (400 mg/kg of body weight per day), and vancomycin (150 mg/kg of body weight per day), which reduced the titers of bacteria by 2.27, 2.76, and 2.85 log10 (CFU/g, respectively, compared with controls. While ampicillin-sulbactam and vancomycin were equally efficacious in reducing titers of bacteria in vegetations, no animals were cured (defined as < 2 log10 CFU/g of vegetation) by either agent, whether treatment was continued for 3 or 7 days. The addition of gentamicin was not associated with increased killing in rabbits infected with the aminoglycoside-resistant isolate. Both high-dose ampicillin-sulbactam and vancomycin regimens demonstrated significant, continued reduction in bacterial titers with the longer periods of treatment (P < or = 0.05); 7-day treatment with high-dose ampicillin-sulbactam produced a greater reduction in bacterial titers in vegetation than 7-day treatment with vancomycin (P < or = 0.05). We conclude that ampicillin-sulbactam and vancomycin are equally effective in the treatment of experimental endocarditis due to beta-lactamase-producing, highly gentamicin-resistant E. faecalis. The optimum therapy for such infections in humans is not known.

Ampicillin↗
PubMed1992

Infections due to beta-lactamase-producing, high-level gentamicin-resistant Enterococcus faecalis.

OBJECTIVE: To investigate the risk factors, clinical features, molecular epidemiology, and treatment outcomes associated with an outbreak of infections due to beta-lactamase-producing, high-level gentamicin-resistant Enterococcus faecalis. DESIGN: Case-control and molecular genetics study. SETTING: Tertiary care Veterans Affairs hospital. PATIENTS: Sixty-five patients infected or colonized with beta-lactamase-producing high-level gentamicin-resistant E. faecalis (case patients) were matched and compared with 65 randomly selected patients infected or colonized with beta-lactamase-negative, gentamicin-susceptible E. faecalis. MEASUREMENTS AND MAIN RESULTS: During the 20-month study period, 124 of 1506 isolates (8.2%) of E. faecalis from 70 patients were found to produce beta-lactamase. Univariate analysis showed older age, higher APACHE II score, nosocomial acquisition, recent surgical procedure, total parenteral nutrition, and antibiotic treatment to be significantly associated with the acquisition of beta-lactamase-producing, high-level gentamicin-resistant E. faecalis. A multivariate analysis, done using stepwise multiple logistic regressions, showed that only two variables remained significant: an APACHE II score greater than 6 (odds ratio, 9.5; 95% CI, 4.4 to 20.3) and antibiotic treatment (odds ratio, 10.2; CI, 4.5 to 23.2). The mortality rate for case patients was 7.7% (5 of 65 patients; CI, 1.2% to 14.2%); no control patient died. Of 23 infections occurring in case patients, 13 were treated with "inappropriate" antibiotics (regimens that included a beta-lactamase-unstable antibiotic); 2 patients improved and 11 had complete resolution of disease. "Appropriate" treatments (regimens that included a beta-lactamase-stable antibiotic) were used in 10 patients; 5 of 10 infections were fatal. Restriction enzyme digests of total chromosomal DNA showed nearly identical patterns for selected isolates of beta-lactamase-producing, high-level gentamicin-resistant E. faecalis, suggesting dissemination through the hospital of a single strain of E. faecalis. CONCLUSIONS: Fatal infections were observed despite treatment with beta-lactamase-stable antibiotics. The risk for infection or colonization with beta-lactamase-producing, high-level gentamicin-resistant E. faecalis was strongly associated with severe underlying disease (acute physiology and chronic health evaluation [APACHE] II score, greater than 6) and previous antibiotic treatment. These results may be useful in targeting high-risk patients for infection-control interventions.

Case-Control Studies↗
PubMed1992

Isolation of a beta-lactamase-producing, aminoglycoside-resistant strain of Enterococcus faecium.

Beta-Lactamase-producing, aminoglycoside-resistant strains of Enterococcus faecalis have been isolated from different geographic areas and are endemic at our institution. We report the isolation of a beta-lactamase-producing, aminoglycoside-resistant strain of E. faecium. The beta-lactamase was plasmid mediated and transferable with high frequency into a plasmid-free E. faecalis recipient strain. MICs suggested that the E. faecium strain also contained intrinsic (chromosomal) resistance to penicillins.

Aminoglycosides↗
PubMed1991

Are universal precautions effective in reducing the number of occupational exposures among health care workers? A prospective study of physicians on a medical service.

Using a daily questionnaire, we prospectively studied 277 physicians from two hospital medical services for incidents of exposure to blood and body fluids and barrier use before and after the implementation of universal precautions. We found that implementation significantly increased the frequency of barrier use during exposure incidents from 54% before implementation to 73% after implementation of universal precautions. Implementation led to a decrease in the number of exposure incidents that resulted in direct contact with blood and body fluids (actual exposures), from 5.07 to 2.66 exposures per physician per patient care month, and to an increase in averted exposures in which direct contact was prevented by the use of barrier devices, from 3.41 exposures per patient care month before implementation to 5.90 exposures per patient care month after implementation. Implementation affected neither the types of body fluid or procedures involved nor the overall rate of exposure incidents (8.5 per patient care month) but, through an increase in barrier use, it did prevent direct contact with blood and body fluids and thus converted what would have been an actual exposure into an averted one. We conclude that universal precautions were effective in reducing the risk of occupational exposures among physicians on a medical service.

Body Fluids↗