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Biomedical subjects

K Y Yuen

Publications and source records attributed to K Y Yuen.

At least 91 records · Page 5Linked to original sources
PubMed2002

Surgical complications and outcome of pediatric liver transplantation in Hong Kong.

PURPOSE: The aim of this study was to analyze the early and late results of pediatric liver transplantation, with particular reference to complications that required surgical or radiologic intervention. METHODS: The records and code sheets of children who underwent liver transplantation in the authors' institution between September 1993 and December 2001 were reviewed. RESULTS: Twenty-nine children (16 boys and 13 girls) underwent 31 liver transplantations (23 living donor, 8 cadaveric donor) during the study period. The ages of the children ranged from 4 months to 132 months (median, 16 months). Eighteen children had complications that required surgical or radiologic interventional procedures. Complications included, among others, hepatic vein thrombosis (n = 1, 3%), hepatic vein stenosis (n = 2, 7%), portal vein thrombosis (n = 2, 7%), biliary stricture (n = 3, 10%), bile leakage (n = 2, 7%), hepatic artery pseudoaneurysm (n = 1, 3%), jejuno-jejunostomy leakage (n = 1, 3%), graft hepatitis (n = 1, 3%), and posttransplant lymphoproliferative disorder (n = 2, 7%). In addition, 6 children (21%) suffered from intraabdominal bleeding from a variety of causes. After appropriate interventions, at a median follow-up of 38 months (range, 1 to 96 months), patient and graft survival rates were 79% and 74%, respectively. The retransplantation rate was only 7%. There was no incidence of hepatic artery thrombosis. All living donors remain alive and well. CONCLUSIONS: Complications are inevitable in pediatric liver transplantation. However, with timely recognition and active intervention, a good outcome can be achieved.

Child↗
PubMed2002

Speechless after bone marrow transplantation: a rare complication of parainfluenza virus related group in an adult.

Upper respiratory tract (URT) viral infections may cause severe consequences during myeloablative bone marrow transplantation (BMT). We present a patient with parainfluenza virus (PIV) infection during the course of BMT. He remained relatively asymptomatic during the course of cytopenia, but presented with complete loss of voice and severe laryngitis a few days after engraftment, which is not usual for adult PIV infections. Seroconversion to PIV and marked increase in antibody titres was demonstrated, with complete lymphoid engraftment. Our case illustrated that the virulence of some URT viral infections depend on host immune factors, and may remain latent until graft versus host responses can be mounted.

Acute Disease↗
PubMed2002

Characterization of a laboratory-generated variant of BPS beta-lactamase from Burkholderia pseudomallei that hydrolyses ceftazidime.

Burkholderia pseudomallei produces an Ambler class A beta-lactamase, known as BPS-1. The beta-lactamase gene from a laboratory-derived, ceftazidime-resistant strain of B. pseudomallei (LH-1-2) was cloned and expressed in Escherichia coli. The beta-lactamase, named BPS-1m, had an identical isoelectric focusing point (pI 7.7) to that of BPS-1, but differed in having a stronger hydrolytic activity against ceftazidime. Susceptibility testing showed that BPS-1m when expressed in E. coli conferred resistance to ceftazidime (MIC >or= 32 mg/L). The amino acid sequence of BPS-1m differed from that of BPS-1 by a Pro-to-Ser change at position 167 in the omega loop.

Amino Acid Substitution↗
PubMed2002

Identification by 16S ribosomal RNA gene sequencing of Arcobacter butzleri bacteraemia in a patient with acute gangrenous appendicitis.

AIMS: To identify a strain of Gram negative facultative anaerobic curved bacillus, concomitantly isolated with Escherichia coli and Streptococcus milleri, from the blood culture of a 69 year old woman with acute gangrenous appendicitis. The literature on arcobacter bacteraemia and arcobacter infections associated with appendicitis was reviewed. METHODS: The isolate was phenotypically investigated by standard biochemical methods using conventional biochemical tests. Genotypically, the 16S ribosomal RNA (rRNA) gene of the bacterium was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the GenBank by multiple sequence alignment. Literature review was performed by MEDLINE search (1966-2000). RESULTS: The bacterium grew on blood agar, chocolate agar, and MacConkey agar to sizes of 1 mm in diameter after 24 hours of incubation at 37 degrees C in 5% CO2. It grew at 15 degrees C, 25 degrees C, and 37 degrees C; it also grew in a microaerophilic environment, and was cytochrome oxidase positive and motile, typically a member of the genus arcobacter. Furthermore, phenotypic testing showed that the biochemical profile of the isolate did not fit into the pattern of any of the known arcobacter species. 16S rRNA gene sequencing showed one to two base differences between the isolate and A butzleri, but 35 to 39 base differences between the isolate and A cryaerophilus, indicating that the isolate was a strain of A butzleri. Only three cases of arcobacter bacteraemia with detailed clinical characteristics were found in the English literature. The sources of the arcobacter species in the three cases were largely unknown, although the gastrointestinal tract is probably the portal of entry of the A butzleri isolated from the present case because the two concomitant isolates (E coli and S milleri) in the blood culture were common flora of the gastrointestinal tract. In addition, A butzleri has previously been isolated from the abdominal contents or peritoneal fluid of three patients with acute appendicitis. CONCLUSIONS: 16S rRNA gene sequencing was useful in the identification of the strain of A butzleri isolated from the blood culture of a patient with acute gangrenous appendicitis. Arcobacter bacteraemia is rare. Further studies using selective medium for the delineation of the association between A butzleri and acute appendicitis are warranted.

Acute Disease↗
PubMed2002

Ralstonia pickettii bacteraemia in a cord blood transplant recipient.

A seven-year old boy with acute lymphoblastic leukemia underwent an HLA mismatched cord blood transplant. He developed grade 2 mucositis requiring morphine infusion and grade 3-4 hyperacute graft-versus-host disease affecting the skin, gastrointestinal tract, and liver requiring pulse methylprednisolone. On days 21, 23, and 24 post-transplant, blood culture obtained through the central line and periphery were positive for Ralstonia pickettii. The same strain (with the same biochemical profile and antibiotic susceptibility pattern) was also recovered from surveillance throat swab cultures from day 11 to day 24 and surveillance rectal swab cultures from day 16 to day 24. The patient responded to intravenous cefoperazone/sulbactam and ciprofloxacin and blood culture became negative 3 days after commencement of the antibiotics. Although R. pickettii is of low virulence and is a frequent contaminant of blood cultures, it should not be overlooked when it is repeatedly recovered from sterile body fluids, especially in immunocompromised hosts.

Bacteremia↗
PubMed2002

Perianal abscess caused by Propionibacterium avidum in a cirrhotic patient.

We describe the first case of community-acquired Propionibacterium avidum subcutaneous tissue infection in a cirrhotic patient. A 70-year-old Chinese male with a 2-year history of hepatitis B virus-induced chronic liver failure and hemorrhoidectomy 17 months previously presented with a painful left buttock abscess, which was culture positive for P. avidum. Being a normal flora of skin with low pathogenicity, there have been only 3 case reports on P. avidum infection, all associated with surgical intervention within 2 to 6 weeks before the onset of P. avidum infection. We hereby review the literature on P. avidum summarizing

Abscess↗
PubMed2002

Ten-year experience with liver transplantation at Queen Mary Hospital: retrospective study.

OBJECTIVE: To report the experience with liver transplantation at the Queen Mary Hospital from 1991 to 2000. DESIGN: Retrospective study. SETTING: Liver transplant centre of a University teaching hospital, Hong Kong. PATIENTS: One hundred and forty-eight patients (127 adults and 21 children) who underwent a total of 155 liver transplants using 75 cadaver grafts (full-size, 67; reduced-size, 5; split, 3) and 80 living donor grafts (left lateral segment, 15; left lobe, 6; right lobe, 59) from October 1991 to December 2000 were reviewed. MAIN OUTCOME MEASURES: Graft and patient survival rate. RESULTS: The most common disease indications for liver transplantation were chronic hepatitis B-related liver disease (n=74) in adults and biliary atresia (n=14) in children. Eighteen patients had hepatocellular carcinoma. Forty-eight (31%) liver transplants (three ABO-incompatible) were performed in high-urgency situations for patients requiring intensive care. The proportion of living donor liver transplants was 47.7% in adults and 73.9% in children. The overall 1-year and 5-year patient survival rates were 82% and 77%, respectively. The survival of high-risk recipients, such as those with fulminant hepatic failure (80%), chronic hepatitis B (81%), or hepatocellular carcinoma (94%), was not inferior to that of other patients. CONCLUSION: Over the last decade, the promotion of (cadaver) organ donation through public education coupled with innovative techniques in living donor liver transplantation have enabled a liver transplantation programme to be established in Hong Kong with gratifying results.

Adolescent↗
PubMed2001

Adoptive transfer of autologous Epstein-Barr virus-specific cytotoxic T cells for nasopharyngeal carcinoma.

Tumor cells from NPC patients are regularly and latently infected with EBV. To examine whether the virus serves as target for immune intervention of the cancer, we determined levels of EBV-specific CTLp in peripheral blood from NPC patients, long-term survivors of the cancer and healthy subjects. CTLp levels of test subjects varied between 3- 3,000/10(6) PBMCs. The plasma EBV burden increased when the CTLp level fell below 150, whereas the EBV burden of PBMCs was not correlated with CTLp level. Compared with healthy carriers, CTLp levels of patients were lower and varied over a wider range, between 3-1,500/10(6) PBMCs. The quantitative immune deficit was probably attributed to the tumor because, first, CTLp in survivors was restored to levels similar to those in healthy carriers after the tumor had been successfully treated. Second, the CTLp level changed as disease progressed, being lower in local disease, increased in locoregional disease and decreased again when the tumor metastasized. Based on these findings, 4 patients with advanced disease were infused with 5 x 10(7)-3 x 10(8) autologous EBV CTLs. The treatment was safe and unaccompanied by inflammatory or other complications, but whether it improved tumor control could not be discerned from the large tumor bulk. Nevertheless, the treatment regularly increased CTLp levels of patients, maintained it at higher levels for protracted periods and, in 3 patients, restored host surveillance of EBV replication, reducing the plasma EBV burden. Taken together, these results provided a rationale to further explore EBV as a target of immune intervention of NPC.

Adoptive Transfer↗
PubMed2001

Quantification of polyoma BK viruria in hemorrhagic cystitis complicating bone marrow transplantation.

Polyoma BK virus (BKV) is frequently identified in the urine of bone marrow transplantation (BMT) patients with hemorrhagic cystitis (HC). However, viruria is common even in asymptomatic patients, making a direct causative role of BKV difficult to establish. This study prospectively quantified BK viruria and viremia in 50 BMT patients to define the quantitative relationship of BKV reactivation with HC. Adenovirus (ADV) was similarly quantified as a control. More than 800 patient samples were quantified for BKV VP1 gene with a real-time quantitative polymerase chain reaction. Twenty patients (40%) developed HC, 6 with gross hematuria (HC grade 2 or higher) and 14 with microscopic hematuria (HC grade 1). When compared with asymptomatic patients, patients with HC had significantly higher peak BK viruria (6 x 10(12) versus 5.7 x 10(7) genome copies/d, P <.001) and larger total amounts of BKV excreted during BMT (4.9 x 10(13) versus 7.7 x 10(8) genome copies, P <.001). There was no detectable increase in BK viremia. Binary logistic regression analysis showed that BK viruria was the only risk factor, with HC not related to age, conditioning regimen, type of BMT, and graft-versus-host disease. Furthermore, the levels of ADV viruria in patients with or without HC were similar and comparable with those of BK viruria in patients without HC, suggesting that the significant increase in BK viruria in HC patients was not due to background viral reactivation or damage to the urothelium. BK viruria was quantitatively related to the occurrence of HC after BMT.

Adenoviridae↗
PubMed2001

Therapeutic efficacy of hepatitis B surface antigen-antibodies-recombinant DNA composite in HBsAg transgenic mice.

Therapeutic efficacy of HBsAg-anti-HBs-recombinant DNA harboring hepatitis B virus (HBV) S gene complex was compared with three other therapeutic vaccine candidates (recombinant HBsAg, HBsAg complexed to anti-HBs antibodies and naked plasmid DNA encoding the HBV S gene). After four injections at 3-week intervals, the most pronounced decrease of serum HBsAg, the highest titer of anti-HBs response, the highest level of interferon-gamma produced by splenocytes and potent cytotoxicity T cell response were observed in the HBsAg-anti HBs-sDNA immunized group. Reduced expression of HBsAg in hepatocytes was also shown. The therapeutic mechanism of HBsAg-anti-HBs-DNA was speculated as modulation of HBsAg presentation via both endogenous and exogenous pathways.

Animals↗
PubMed2001

Unique immunogenicity of hepatitis B virus DNA vaccine presented by live-attenuated Salmonella typhimurium.

A novel vaccine for hepatitis B virus (HBV) was designed by putting a naked DNA vaccine carrying hepatitis B surface antigen (HBsAg) into live-attenuated Salmonella typhimurium. Mucosal immunization by the oral route in mice showed significantly stronger cytotoxic T lymphocyte (CTL) response than recombinant HBsAg vaccination (P < 0.01 at an effector:target ratio of 100:1), while comparable to intramuscular naked DNA immunization at all effector:target ratios. Contrary to previous reports on naked DNA vaccines given intramuscularly, the IgG antibody response induced by the mucosal DNA vaccine is relatively weak when compared to recombinant HBsAg vaccine (P < 0.001 at day 21). These findings are supported by a high interferon-gamma but a low interleukin-4 level detected in the supernatant of splenic cell cultures obtained from mucosally immunized mice. As distinct to recombinant HBsAg vaccine which is effective for protection, oral mucosal DNA vaccine should be considered as a candidate for therapeutic immunization in chronic HBV infection, donor immunization before adoptive transfer of HBV-specific CTL to HBsAg positive bone marrow transplant recipients, and immunization of non-responders to recombinant HBsAg vaccine. This strongly cellular and relatively absent humoral response may make this vaccine a better candidate as a therapeutic vaccine for chronic HBV carriers than naked DNA vaccines, as the humoral response is relatively less important for the clearance of HBV from hepatocytes, but its presence may lead to side effects such as serum sickness and immune complex deposition in chronic HBV carriers.

Animals↗
PubMed2001

Cell-wall-deficient bacteria and culture-negative febrile episodes in bone-marrow-transplant recipients.

BACKGROUND: Although about 75-80% of neutropenic fevers are thought to be caused by infections, a causal organism can be confirmed microbiologically or suspected clinically in only 30-50%, and even fewer of these cases (16%) have a documented bacteraemia. The cause of neutropenic fever in the remaining cases remains elusive. We investigate the role of cell-wall-deficient bacteria in bone-marrow transplantation (BMT). METHODS: Blood cultures were obtained from bone-marrow-transplant recipients and were inoculated into an aerobic bottle with resin, an anaerobic bottle, and a bottle to isolate cell-wall deficient bacteria. When growth was detected in the blood-culture bottle for cell-wall-deficient bacteria, 20 microL of the broth was subcultured and the isolate identified by standard biochemical methods. The microbiological findings were correlated with the clinical characteristics of the patients. FINDINGS: From the 86 BMT recipients enrolled into the study, 798 sets of blood cultures were sent for laboratory analysis. 55 blood cultures were positive in the aerobic bottle, and the same isolates were also detected in 52 blood-culture bottles for cell-wall-deficient forms. For 20 sets of blood cultures, the isolates were detected only in the bottle for cell-wall-deficient forms. Blood for 13 (65%) of these 20 sets were sampled in the pre-engraftment neutropenic period, three (15%) during conditioning when the absolute neutrophil count was above 0.5 x 10(3)/L, and four (20%) in the post-engraftment period. 17 (85%) of the isolates were gram positive: four (20%) were Staphylococcus spp and ten (50%) were Bacillus spp. Antibiotic treatment was successful in 19 (95%) of 20 episodes. INTERPRETATION: Bacteraemia due to cell-wall-deficient forms causes a significant proportion of so-called culture-negative febrile episodes in BMT recipients.

Analysis of Variance↗
PubMed2001

Candida tropicalis and Penicillium marneffei mixed fungaemia in a patient with Waldenström's macroglobulinaemia.

A patient with Waldenstrom's macroglobulinaemia who had previously been treated with cladribine presented with septic arthritis caused by Escherichia coli. The patient's condition subsequently deteriorated, and he succumbed to pneumonia and mixed fungaemia due to Candida tropicalis and Penicillium marneffei. Profound lymphopenia coexisted with fungaemia. This is the first reported case of mixed Penicillium marneffei and Candida fungaemia and penicilliosis marneffei in a patient with Waldenstrom's macroglobulinaemia. Penicilliosis marneffei should be considered as a potential complication in patients with markedly impaired cell-mediated immunity who have travelled to or resided in endemic areas. Patients who have undergone therapy with purine nucleoside analogues such as fludarabine and cladribine are also at risk.

Aged↗
PubMed2001

Immunorestitution diseases in patients not infected with HIV.

The aim of this study was to assess the clinical spectrum of immunorestitution disease (IRD) in hospitalized patients over a 12-month period. In nine of 18 patients who presented with clinical deterioration during reduction or cessation of immunosuppressants (n = 6) or bone marrow engraftment (n = 3), IRD cases included the following infections: scabies infestation (n = 1); gastric strongyloidiasis (n = 1); hepatosplenic candidiasis (n = 1); methicillin-resistant Staphylococcus aureus abscess formation (n = 2); polyomavirus-related hemorrhagic cystitis (n = 3); and influenza A pneumonitis (n = 1). Immunopathological damage during withdrawal of immunosuppression is an incidental way to uncover an asymptomatic infectious disease. Serial monitoring of hematological and clinical profiles is essential in making a diagnosis of IRD.

Adult↗
PubMed2001

Legionella pneumonia and bacteraemia in association with protein-losing enteropathy after Fontan operation.

A 20-year-old young man suffered from severe protein-losing enteropathy 4 years after Fontan operation. His postoperative haemodynamics were unfavourable in terms of poor myocardial contractility and moderate atrioventricular prosthetic paravalvar leakage. A 2-week trial of steroid therapy for protein-losing enteropathy was given without success. The clinical course was complicated by Legionella pneumophila pneumonia and bacteraemia, which respond to the combination therapy with intravenous erythromycin and ciprofloxacin. The vulnerability of the patient to infection was related to an immuno-deficiency state secondary to protein-losing enteropathy and steroid therapy. Steroids should be used with caution in the management of protein-losing enteropathy after Fontan operation.

Adult↗