Search PubMed⌕ Search

Biomedical subjects

K Y Yuen

Publications and source records attributed to K Y Yuen.

At least 163 records · Page 9Linked to original sources
PubMed1998

Clonorchiasis in bone marrow transplant recipients.

Among 380 bone marrow transplant (BMT) recipients, five cases (1.3%) of clonorchiasis were observed from 1991 to 1996. Clonorchis sinensis infection was evident in the results of stool examinations performed for screening purposes 7 days before bone marrow transplantation. Salmonella species were isolated concomitantly from the stools of two of the five patients. None of the patients had symptoms due to clonorchiasis. Ultrasonography did not show dilated hepatobiliary ducts, stones, or periportal fibrosis. Fatty liver changes were detected in one patient. All five patients received praziquantel (25 mg/kg po t.i.d. for 1 day) before bone marrow transplantation. Only two patients who underwent allogeneic transplantation had mild venoocclusive disease of the liver with transient hyperbilirubinemia and mildly elevated liver enzyme levels, whereas hyperbilirubinemia or elevated serum alanine aminotransferase levels, related to conditioning toxicity, occurred in two other patients. After treatment with praziquantel, stool examination for all five patients were negative for C. sinensis ova. In addition, Salmonella species were not detected after ciprofloxacin prophylaxis. All five patients survived for > 300 days. Given the availability of effective therapy and in the absence of excessive complications, clonorchiasis is not a contraindication to bone marrow transplantation.

Adult↗
PubMed1998

Comparison of a novel, inhibitor-potentiated disc-diffusion test with other methods for the detection of extended-spectrum beta-lactamases in Escherichia coli and Klebsiella pneumoniae.

A novel, inhibitor-potentiated disc-diffusion test for detecting extended-spectrum beta-lactamases (ESBLs) in bacteria was evaluated. This test uses the principle of augmentation (by > or = 10 mm) of inhibition zones produced by ceftazidime, cefotaxime, ceftriaxone or aztreonam discs on Mueller-Hinton agar supplemented with clavulanate (4 mg/L). The test was initially compared with the double-disc synergy test, Kirby-Bauer disc-diffusion test and Etest ESBL screen with a panel of 45 reference strains with known resistance profiles. This panel consisted of 27 ESBL-positive Escherichia coli strains expressing 14 Bush group 2be enzymes and 18 other E. coli and Klebsiella pneumoniae strains (14 non-ESBL beta-lactamase producers and four non-beta-lactamase producers). The Kirby-Bauer disc-diffusion test was the least sensitive method: 11-44% of the ESBL-positive control strains were misclassified as susceptible to ceftazidime, cefotaxime, ceftriaxone or aztreonam when interpreted by National Committee for Clinical Laboratory Standards (NCCLS) criteria. The sensitivities of the inhibitor-potentiated disc-diffusion test, the double-disc synergy test (when discs were 25 or 30 mm apart) and the Etest ESBL screen (with a breakpoint of > 4-fold reduction in ceftazidime MIC in the presence of clavulanate) were 100%, 96% and 89-96%, respectively. The inhibitor-potentiated disc-diffusion test was further evaluated with 81 E. coli and K. pneumoniae clinical isolates, which were identified as putative ESBL-producers by the double-disc synergy test. For these isolates, the sensitivity of both the inhibitor-potentiated disc-diffusion test and the Etest ESBL screen was 100%. In conclusion, the inhibitor-potentiated disc-diffusion test is a sensitive, convenient and inexpensive method of screening for ESBLs in E. coli and K. pneumoniae isolates, with potential for incorporation into routine clinical laboratory service.

Anti-Bacterial Agents↗
PubMed1998

MP1 encodes an abundant and highly antigenic cell wall mannoprotein in the pathogenic fungus Penicillium marneffei.

We cloned the MP1 gene, which encodes an abundant antigenic cell wall mannoprotein from the dimorphic pathogenic fungus Penicillium marneffei. MP1 is a unique gene without homologs in sequence databases. It codes for a protein, Mp1p, of 462 amino acid residues, with a few sequence features that are present in several cell wall proteins of Saccharomyces cerevisiae and Candida albicans. It contains two putative N glycosylation sites, a serine- and threonine-rich region for O glycosylation, a signal peptide, and a putative glycosylphosphatidylinositol attachment signal sequence. Specific anti-Mp1p antibody was generated with recombinant Mp1p protein purified from Escherichia coli to allow further characterization of Mp1p. Western blot analysis with anti-Mp1p antibody revealed that Mp1p has predominant bands with molecular masses of 58 and 90 kDa and that it belongs to a group of cell wall proteins that can be readily removed from yeast cell surfaces by glucanase digestion. In addition, Mp1p is an abundant yeast glycoprotein and has high affinity for concanavalin A, a characteristic indicative of a mannoprotein. Furthermore, ultrastructural analysis with immunogold staining indicated that Mp1p is present in the cell walls of the yeast, hyphae, and conidia of P. marneffei. Finally, it was observed that infected patients develop a specific antibody response against Mp1p, suggesting that this protein represents a good cell surface target for host humoral immunity.

Amino Acid Sequence↗
PubMed1998

Detection of specific antibodies to an antigenic mannoprotein for diagnosis of Penicillium marneffei penicilliosis.

The disseminated and progressive fungal disease Penicillium marneffei penicilliosis is one of the most common infectious diseases in AIDS patients in Southeast Asia. To diagnose systemic penicilliosis, we developed an enzyme-linked immunosorbent assay (ELISA)-based antibody test with Mp1p, a purified recombinant antigenic mannoprotein of P. marneffei. Evaluation of the test with guinea pig sera against P. marneffei and other pathogenic fungi indicated that this assay was specific for P. marneffei. Clinical evaluation revealed that high levels of specific antibody were detected in two immunocompetent penicilliosis patients. Furthermore, approximately 80% (14 of 17) of the documented penicilliosis patients with human immunodeficiency virus tested positive for the specific antibody. No false-positive results were found for serum samples from 90 healthy blood donors, 20 patients with typhoid fever, and 55 patients with tuberculosis, indicating a high specificity of the test. Thus, this ELISA-based test for the detection of anti-Mp1p antibody can be of significant value as a diagnostic for penicilliosis.

AIDS-Related Opportunistic Infections↗
PubMed1998

Identification of acinetobacters on blood agar in presence of D-glucose by unique browning effect.

A positive phenotypic characteristic of glucose-oxidizing acinetobacters was demonstrated with blood agar containing D-glucose. Glucose-oxidizing Acinetobacter baumannii, Acinetobacter genospecies 3, Acinetobacter lwoffii, and Acinetobacter genospecies 13 sensu Tjernberg and Ursing caused a unique brown discoloration of media supplemented with 5% blood (of horse, sheep, or human origin) and an aldose sugar (0.22 M D-glucose, D-galactose, D-mannose, D-xylose, or lactose). The browning effect was not observed when a ketose sugar (D-fructose or sucrose) was substituted for the aldose sugar or under high osmolarity in the presence of mannitol, glycerol, or sodium chloride. Other gram-negative nonfermenters (non-glucose-oxidizing acinetobacters, Pseudomonas aeruginosa, other Pseudomonas spp., Stenotrophomonas maltophilia, Flavobacterium spp., and Moraxella spp.) did not cause similar discoloration. This novel browning effect may serve as an alternative trait for identifying glucose-oxidizing acinetobacters.

Acinetobacter↗
PubMed1998

Rhodococcus equi lung abscess complicating Evan's syndrome treated with corticosteroid.

We report a case of Rhodococcus equi, an unusual pathogen, causing a right upper lobe lung abscess in a patient with Evan's syndrome (auto-immune haemolytic anaemia and thrombocytopenia) who was treated with high-dose corticosteroid therapy. The patient was treated successfully with clarithromycin, vancomycin, ciprofloxacin and imipenen which appear to be effective in combination for this unusual condition in which the treatment regimen has been controversial.

Actinomycetales Infections↗
PubMed1998

Inhaled fluticasone reduces sputum inflammatory indices in severe bronchiectasis.

Although corticosteroid therapy might be clinically beneficial for bronchiectasis, very little is known of its effects on the inflammatory and infective markers in bronchiectasis. We have therefore performed a double-blind, placebo-controlled study to evaluate the effects of a 4-wk administration of inhaled fluticasone in bronchiectasis. Twenty-four patients (12 female; mean age 51 yr) were randomized into receiving either inhaled fluticasone (500 microgram twice daily) via the Accuhaler device (n = 12) or placebo. At each visit, spirometry, 24-h sputum volume, sputum leukocyte density, bacterial densities, and concentrations of interleukin (IL)-1beta, IL-8, tumor necrosis factor-alpha (TNF-alpha), and leukotriene B4 (LTB4) were determined. There was a significant (p < 0.05) decrease in sputum leukocyte density and IL-1beta, IL-8, and LTB4 after fluticasone treatment. The fluticasone group had one and the placebo group three episodes of exacerbation. There were no significant changes in spirometry (p > 0.05) or any reported adverse reactions in either group. The results of this study show that high-dose fluticasone is effective in reducing the sputum inflammatory indices in bronchiectasis. Large-scale and long-term studies are indicated to evaluate the effects of inhaled steroid therapy on the inflammatory components in bronchiectasis.

Administration, Inhalation↗
PubMed1998

Risk factors for pulmonary tuberculosis in bone marrow transplant recipients.

Little is known about the profile of infection with Mycobacterium tuberculosis in bone marrow transplant (BMT) recipients. Of five BMT series with a total of more than 5,000 patients, only 10 cases of M. tuberculosis infection were described, with an overall incidence of 0.19%. We have conducted a prospective evaluation of 183 consecutive BMT recipients, and 10 patients were found to develop pulmonary tuberculosis post-BMT, yielding an incidence of 5.5%. We described the clinical features of these 10 patients, and analyzed the risk factors for development of tuberculosis using age- and sex-matched case control subjects who did not develop the disease. The median age of the 10 patients who developed tuberculosis was 29 yr (range, 17 to 40 yr). The median time for onset of symptoms was 150 d (range, 23 to 550 d), mainly presenting with fever and cough, with infiltrates on chest radiograph. Respiratory tract specimens, mostly sputum, yielded positive smears for acid-fast bacilli in three and positive M. tuberculosis culture in eight, whereas lung tissue histology was the first diagnostic test in two patients. Treatment with standard antituberculosis drugs for a longer duration was highly effective, with no excessive side effects. Risk factors identified for development of tuberculosis included allogeneic BMT (p < 0.05, relative risk [RR] = 23.7), total body irradiation (p < 0. 05, RR = 4.9), and chronic graft-versus-host disease (GVHD) (p < 0. 05, RR = 3.6). It is postulated that chronic GVHD predisposed to development of tuberculosis mainly via disruption of host reconstitution of immune defenses against M. tuberculosis.

Adolescent↗
PubMed1998

The effect of Pseudomonas aeruginosa infection on clinical parameters in steady-state bronchiectasis.

STUDY OBJECTIVE: To investigate the effect of Pseudomonas aeruginosa infection on clinical parameters in Chinese patients with noncystic fibrosis and steady-state bronchiectasis. DESIGN: Prospective, cross-sectional clinicomicrobiological study with informed consent. SETTING: Consecutive outpatient recruitment from a specialist bronchiectasis respiratory clinic. PATIENTS: Outpatients (n = 100; 62 women; 55.1+/-16.7 years old; FEV1/FVC 1.4+/-0.7/2.1+/-0.9 L), who had stable respiratory symptoms for more than 3 weeks. MEASUREMENTS AND RESULTS: Respiratory pathogens isolated from the sputum were: Pseudomonas aeruginosa (33), Haemophilus influenzae (10), Moraxella catarrhalis (2), other Gram-negative bacilli (5), Streptococcus pneumoniae (6), Staphylococcus aureus (5), mycobacteria (3), and yeast (1). Clinical parameters in patients with positive isolation of P aeruginosa were compared with those without the organism in the sputum culture (non-P aeruginosa). In the P aeruginosa group, the FEV1/FVC ratio and sputum volume were lower (p < 0.005) and higher (p < 0.0001), respectively, than those of the non-P aeruginosa group. The FEV1/FVC ratio (< 60%) and sputum volume (grading > 5) were independently associated with a positive sputum isolation of P aeruginosa with odds ratios of 3.1 (confidence interval [CI] 1.2 to 8.4; p < 0.01) and 4.7 (CI 1.6 to 13.3; p < 0.001), respectively. CONCLUSIONS: P aeruginosa is the predominant respiratory pathogen isolated in the sputum of Chinese patients with steady-state bronchiectasis, and its isolation is associated with high sputum output (> or = 75th quartile) and moderately severe airflow obstruction (FEV1/FVC < 60%).

Adult↗
PubMed1998

Direct detection of Mycobacterium tuberculosis in respiratory specimens using an automated DNA amplification assay and a single tube nested polymerase chain reaction (PCR).

The performance of an automated DNA amplification assay (Roche Cobas Amplicor Mycobacterium Tuberculosis Test (aPCR) was compared with an in-house single tube nested polymerase chain reaction (nPCR) for the direct detection of Mycobacterium tuberculosis in respiratory specimens. Among 385 specimens, 56 were culture positive for mycobacteria (44 positive for Mycobacterium tuberculosis and 12 positive for non-tuberculosis mycobacteria). The diagnostic sensitivities of aPCR and nPCR were 86% and 91% whereas a 100% diagnostic specificity of both assays was attained. By aPCR, inhibitors were detected in 6% of the clinical samples. For nPCR, the usage of a new thermostable DNA polymerase facilitated pre-PCR decontamination using uracil-N-glycosylase and "hot start" in single step procedure. The results of the study indicated that DNA amplification assays, either manual or automated, were rapid and specific tools for diagnosing pulmonary tuberculosis.

Base Sequence↗
PubMed1998

Paediatric liver transplantation: Queen Mary Hospital experience.

OBJECTIVE: To assess the results of paediatric liver transplantation in our institution. METHODS: From September 1993 to November 1996, 10 living-related liver transplants (LRLT) and 3 reduced-size liver transplants (RSLT) were performed on 12 children at our hospital. The medical records of the patients were reviewed. All patients suffered from end-stage liver disease resulting from biliary atresia with failed Kasai's operations. Their ages at initial transplantation ranged from 8 months to 11 years. Excluding the 2 older children aged 7.5 and 11 years, the remaining patients were aged 10.5 months on the average and weighed 6 to 9.5 kg (mean: 6.8 kg) at the time of initial transplantation. RESULTS: All living donors were discharged on postoperative day 4 to 8 and resumed their previous normal activities. All recipients were alive with normal liver function and growing after a follow-up period of 3-40 months (mean: 21 months). The patient survival rate was 100%. One patient with RSLT had hepatitis of undetermined aetiology and underwent retransplant with a graft from her mother. The graft survival rate was 92%. Postoperative complications included: postoperative bleeding (n = 3), hepatic vein stenosis (n = I), biliary-enteric anastomotic stenosis (n = 3), intestinal perforation (n = I) and portal vein thrombosis (n = I). They were all treated promptly. In all patients, the hepatic artery (diameter ranged from 1.5 to 2.5 mm) anastomosis was achieved by microvascular technique. There was no hepatic artery thrombosis in our patients. CONCLUSION: With technical refinements, early detection and prompt treatment of complications, and advances in immunotherapy, excellent results can be achieved in paediatric liver transplantation.

Biliary Atresia↗
PubMed1998

Lack of evidence of active lytic replication of Epstein-Barr and cytomegaloviruses in patients with systemic lupus erythematosus.

OBJECTIVES: Systemic lupus erythematosus (SLE) is a multifactorial disease. Environmental factors such as viral infection(s) have been proposed as pathaetiological factors. There are particular interests in studying lymphotropic viruses such as the Epstein-Barr virus (EBV) and cytomegalovirus (CMV). Although previous case reports and in vitro studies suggested that they may have a role, there is no direct evidence that onset of SLE or disease exacerbation is associated with active infection by these viruses. Using the very sensitive polymerase chain reaction (PCR) technique, we tried to find out evidence of active replication of these viruses in patients with SLE. METHODS: Thirty-four patients with SLE were compared with matched normal controls. Eleven patients were newly diagnosed to have SLE and 18 of the 34 patients had active disease as determined by a SLE Disease Activity Index (SLEDAI) score of > or = 10 at the time of study. RESULTS: Our results showed no evidence of active replication or reactivation of EBV in the leucocytes amongst the newly diagnosed SLE patients, established SLE patients, patients with SLEDAI > or = 10, patients with SLEDAI < 10, and control subjects. There was no evidence of CMV infection in any of the subjects studied. The IgG and IgA responses against EBV early antigen (EA) and viral capsid antigen (VCA) were also studied. The IgG and IgA responses against VCA of EBV were increased in patients with SLE when compared with controls. However, there were no differences in these responses among different subgroups of patients. The mechanism of these responses was not apparent but may represent non-specific hyperimmune responses in these patients. There were no differences in the titre of IgG and IgA against EBV EA between the patient groups and controls. CONCLUSION: There is no direct evidence that either EBV or CMV plays a direct role in the onset and/or exacerbation of SLE.

Antibodies, Viral↗
PubMed1998

Pseudobacteremia with amoxycillin-clavulanic acid-resistant Escherichia coli traced to cross-contamination during blood culture processing.

Escherichia coli has seldom been reported to cause pseudobacteremia. The investigation of an outbreak of amoxycillin-clavulanic acid-resistant E. coli pseudobacteremia is described. Seventeen cases occurred over a five-day period. The source of the E. coli was traced to the blood culture specimen of a patient (index patient) with genuine bacteremia as a result of urinary tract infection. The other 16 case-patients had pseudobacteremia which was found to be the result of cross-contamination during subculture of blood specimens. The E. coli strain was carried over from the culture bottle of the index patient, through the contaminated gloved hands of a technician to the culture bottles of the other 16 cases. Although the pseudobacteremia occurred over a five-day period, they all resulted from cross-contamination during blood culture processing within one day. An early outbreak investigation was prompted by the unusual finding of amoxycillin-clavulanic acid resistance in the case E. coli isolates in a short period. The relatedness of the E. coli strains from the 17 cases was confirmed by arbitrary-primed polymerase chain reaction. Clinicians should be alerted to the possibility of a blood E. coli isolate being a contaminant despite its predominant role as a true pathogen.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed1997

Human herpesvirus-6 and human herpesvirus-7 infections in bone marrow transplant recipients.

Human cytomegalovirus (HCMV), human herpesvirus-6 (HHV-6), and human herpesvirus-7 (HHV-7) DNA in peripheral blood leukocytes (PBL) of 61 bone marrow transplant recipients was monitored weekly during the first 12 weeks post-transplantation by a nested polymerase chain reaction (PCR). Thirty-seven (61%), 17 (28%), and 32 (53%) of patients had one or more PBL specimens positive for HCMV, HHV-6 or HHV-7 DNA, respectively. HHV-7 DNA in PBL during the early post-transplant period was associated with a longer time to neutrophil engraftment (mean 28.8 days vs 19.8 days; P = 0.01). In two patients who failed to engraft, HHV-6 DNA and HHV-7 DNA was detected in plasma and PBL, respectively, early in their post-transplant period. Patients with HCMV disease were more likely to have concurrent HHV-7 DNA in PBL prior to onset of disease than were patients with asymptomatic HCMV infection, suggesting that HHV-7 may be a cofactor in the progression from HCMV infection to HCMV disease. In the 17 patients (179 specimens) in whom viral DNA in plasma was studied (in addition to PBL), a positive result was found only in 3. In each, viral DNA in plasma appeared to correlate with clinically significant disease. HHV-7 DNA in plasma was associated with encephalitis in an allograft recipient.

Acyclovir↗
PubMed1997

Liver transplantation in children: the experience of Queen Mary Hospital, Hong Kong.

Seven living-related liver transplants (LRLT) and two reduced-size liver transplants (RSLT) were performed on eight children who suffered from end-stage liver disease, having previously undergone one to three abdominal operations. Their ages at initial transplantation ranged from 8 months to 11 years (mean 35 months, median 12 months). Excluding the two older children aged 7 and 11 years, respectively, the rest of the children weighed 6 to 9.5 kg (mean 7.3 kg) at the time of the initial transplantation. Seven left lateral segments (S2 + 3) and two left lobes (S2 + 3 + 4) were used; of these the smallest graft had a graft-to-recipient body weight ratio of 0.9%. The volunteer living donors were four mothers, two fathers and one sister who were selected after medical and psychiatric evaluations, and their suitability was confirmed by hematological, biochemical, and radiological criteria. During a follow-up period of 3 to 30 months, all eight children are alive and well with normal liver function, one of them having undergone a retransplant LRLT because of hepatitis of undetermined etiology following a RSLT 1.5 years earlier. All seven donors had an uneventful postoperative course and were discharged on day 4 to 7 postoperatively. They have all resumed normal day-to-day activities. There were no complications in the donor group. A variety of complications occurred in the recipients, all of which were overcome. Operating microscope was used to perform all the arterial anastomoses using microvascular techniques. This method has proven to be a major factor in preventing arterial thrombosis even with the smallest of arterial anastomosis where a 1.5-mm diameter recipient artery was anastomosed to a 2.5-mm diameter donor hepatic artery.

Activities of Daily Living↗